Monday, December 20, 2010

Two stars merge on camera

No, it's not the latest celebrity scandal.  But a group of astronomers think they may have seen two stars in space spiral together, combine in a rare type of stellar eruption, and combine to make a single star.

Our story begins with a type of event called a nova (plural: novae).   Novae are typically thought to be nuclear explosions on the surface of white dwarf stars.  White dwarfs are the remains of stars that have used all of their nuclear fuel.  If a white dwarf can collect enough hydrogen, such as a very near neighbor star, that hydrogen can begin an uncontrolled nuclear fusion reaction.  The result is a dramatic brightening of the white dwarf (sometimes making the otherwise faint star visible to the naked eye).  Careful measurements of novae tend to detect debris from the eruption expanding out into space at speeds of thousands of miles per second.  The white dwarf escapes more or less unscathed, and usually begins collecting more hydrogen for another explosion decades to centuries later.  [Note that novae are different from supernovae, which are tremendous explosions that mark the end of the life of a massive star or the explosion of an entire white dwarf; supernovae are far, far brighter and far more energetic than novae.]

Over the past few decades, a handful of novae have been seen, both in our Milky Way galaxy and in neighboring galaxies, that don't quite match these characteristics.  Sometimes called "red novae", these are brighter than normal novae and spew out material at much slower speeds.  They are also redder in color (hence the name).  I've seen some vigorous debate as to whether red novae are similar to normal novae, or perhaps something different altogether.  One of the most famous red novae was an even known as V838 Monocerotis, and the Hubble Space Telescope has taken a series of dramatic images of the flash of light from this event lighting up the dust in space surrounding the nova:


Light echos from V838 Mon
Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) / H. Bond


In September of 2008, a nova appeared in the constellation Scorpius.  Called V1309 Scorpii, it was soon recognized that this nove belonged to the exotic class of red novae.  A group of astronomers led by Romuald Tylenda of the Nicolaus Copernicus Astronomical Center in Poland also recognized that V1309 Scorpii was located in the field of an experiment called OGLE.  OGLE is an experiment that images certain interesting portions of the sky night after night, looking for brightening of stars due to the bending of light by gravity, called gravitational microlensing.  Since it is impossible to predict which of the millions of stars in OGLE's sights will brighten until it actually happens, data is collected and stored on every visible star in the experiment's view.

So, Prof. Tylenda's group checked OGLE's database at the position of V1309 Scorpii, and they found that there was a star visible before the nova.  This star varied in brightness every 1.4 days in a way that suggests the star was a contact binary star, two stars that orbit each other so closely that their outer layers are actually touching.  The stars may look something like a peanut, like this.  And over the six years that OGLE had been looking at the field containing this star, the period of the stars' orbits had decreased -- the stars were slowly moving closer together!

From 2002 to 2006, the variations in light from the star looked fairly normal. But in 2007, the variations changed.  Instead of something that looked like two stars constantly passing in front of each other as seen from the Earth, the variations looked more like a single star that had one side hotter than the other.  About a year after this, the nova occurred.  And now that the nova has faded away, astronomers see what looks like a single star, with no eclipses, no hot and cool side of the star, just a single red star.

So, through hard work and more than a little luck, Professor Tylenda's team seems to have observed the merger of two stars into a single one.  Before 2007, the two stars were circling each other, getting closer and closer together.  Sometime in 2007, the stars got close enough that the two stars shared a single atmosphere.  Finally, a year later, the centers of the two stars merged together, leading to a tremendous outburst of energy that looked similar to these curious red novae. And it seems clear that there was no white dwarf involved here.

There's still more work that needs to be done to confirm this description of V1309 Scorpii, so this hypothesis explaining this nova could be wrong.  And there are some differences between V1309 Scorpii and the other known red novae, so perhaps other red novae are not merging stars.

The crucial evidence for cracking the case of V1309 Scorpii was the several years of astronomical images collected by the OGLE project.  Now that we know what to look for, perhaps we can search existing databases for similar objects.  Better yet, in a few years, a telescope called the LSST will begin taking series of images of the entire southern hemisphere sky, not just selected areas like OGLE has done.   With some legwork and a little luck, LSST may discover dozens of future red novae so they can be studied in even more detail before the two stars merge together.  The key is knowing what to look for, and Tylenda's team may have unearthed that important clue.

R. Tylenda, M. Hajduk, T. Kamiński, A. Udalski, I. Soszyński, M. K. Szymański, M. Kubiak, G. Pietrzyński, R. Poleski, Ł. Wyrzykowski, & K. Ulaczyk (2010). V1309 Scorpii: merger of a contact binary Astronomy & Astrophysics arXiv: 1012.0163v1

Friday, October 29, 2010

Science and the media: why you shouldn't believe everything your read

A month ago, I blogged about a newly-discovered planet, Gliese 581g, that may or may not be suitable for life.  Since that time, considerable controversy has arisen.  A competing team of planet hunters has claimed that they cannot find the same planet in their data.  After trumpeting an amazing discovery, many of the same media outlets are publishing stories decrying the (possibly) false result.  Confused?  You have a right to be.  Some of the blame for this confusion lies with scientists on both teams, but much lies at the feet of the science media who are reporting the story.  (I'll share in that blame since I didn't question the reality of the planet in my original post, though I did discuss our lack of knowledge about what this planet is truly like).

Today, a friend posted this opinion piece from Marty Robbins published online by the Guardian, which I think does a superb job of summarizing where the reporting went wrong.  To summarize Robbins's summary, the scientists and press releases by both teams clearly state (though sometimes bury) that their discovery / refutation of Gleise 581g is preliminary, and needs to be confirmed by additional data.  In other words, both groups have admitted that they might be wrong in their assessments.  But those cautions are not discussed or only tangentially discussed in most of the media coverage, so the public thinks a preliminary reporting is solid fact.

Scientists, in general, are a cautious bunch, especially near the boundaries of science when we are pushing instruments and methods to their limits.  We try to calculate how likely we are to be right or wrong, but those calculations are themselves dependent on assumptions that can be wrong.  For this reason, exciting new discoveries are often found, later, to be incorrect.  Whether it be planets, dark matter, or medical breakthroughs, we scientists get it wrong.  Sometimes we think we made a mistake, only to find out we were mistaken about the mistake and actually correct in the first place.

Some of my students have gotten upset when I can't answer their insightful questions about topics we've covered in our astronomy class.  They want to know answers, but science doesn't know the answer yet.  I'm trying to help them to realize that science is the process of learning the answers, so a lack of knowledge is not a failure.  It's just a sign we have more work to do.

Science is a human endeavour.  As such, there will be failures, debates, bitter arguments, and oversized egos involved, and there always have been.  It is crucial for the public to realize that these "bad" things are healthy and necessary parts of science, if we want science to advance.  Stridently competing claims such as those surrounding Gliese 581g do not mean that the scientists involved are idiots who deserve to have their funding cut; it means that we are exploring new frontiers.  Astronomy conferences where five teams with five competing claims erupting into shouting matches do not mean that that frontier is hopeless to study, but that there are lots of people who find it interesting, exciting, and important enough to pour their work and emotion into exploring it.

So, when you see competing claims in the media about a new scientific discovery, don't be frustrated and angry by our lack of ability to instantly know all the answers.  If all you want to know is what the right answer is, then tune science out, come back in 50 years and we can tell you.  But if you like the thrill of the chase and the excitement of discovery, competing claims are a call to sit up and pay attention, because some exciting work is going on.

Thursday, October 14, 2010

Loss of another great astronomer

This past weekend I learned that Dr. John Huchra, an astronomer at the Harvard-Smithsonian Center for Astrophysics, passed away of a heart attack.  An obituary detailing Huchra and his contributions has appeared in the New York Times.

Huchra's death has had a profound impact on many astronomers.  Part of it is certainly that his passing was unexpected.  But much larger part is that he was an outstanding human being who was not only passionate about science, but also cared deeply for those around him.  I've seen several moving tributes by friends and colleagues on Facebook and by email.  There is clearly a profound sense of loss among the worldwide astronomical community; we lost a dear member of our family.

(Edited to correct Huchra's affiliation)

Thursday, September 30, 2010

A habitable planet? Maybe.

Artwork by Lynette Cook; image from UC Santa Cruz

This will be short, as I only have a few minutes to blog.  My students seem to want their homeworks graded for some reason.

Yesterday, astronomers at UC Santa Cruz and the Carnegie Observatories announced that they had found the first known planet that may be habitable.  The press release, available here, does a great job of describing the discovery, the discovery process (it was really hard work), and what we know about the planet.  Alas, many of the news stories that have popped up online and on television do a poor job of all of these, which has led to some very garbled announcements.

In short, though, the planet is about three or four times the mass of the Earth, and it orbits a red dwarf star that has at least five other planets.  The star orbits within what astronomers call the "habitable zone", or a region around the star where liquid water can exist on a planet's surface.

The planet, called Gliese 581g, orbits a red dwarf star called Gliese 581 which is about 20 light-years away from Earth -- very close as far as stars go.  Red dwarfs have less mass then the sun and they don't shine nearly as brightly or as hotly, so this planet is located much closer to its parent star than the Earth is to the sun.  This planet's year is only 37 Earth days long.  Being so close to its parent star also means that the planet is likely tidally-locked, so that the same part of the planet always faces the red dwarf star, just like the same face of the Moon always faces the Earth.  This means that half of the planet always sees daytime, and half always sees nighttime.  The day face of the planet could be really hot, and the night side of the planet could be really cold.  On the border between night and day, the temperature could be really comfortable.

However, we don't know a lot of things about this planet.  It was discovered by its gravitational pull on the red dwarf star, so we haven't actually seen the planet yet.  This is the way that many extrasolar planets have been found, and so we are very confident that the planet exists.  We assume it is made of rock, but we aren't positive about that.  If it is made of rock, it is a little larger than the Earth, and the force of gravity will be a little (but not too much) hotter higher.  If astronauts were to visit this planet, they would be able to stand and walk around.

We don't know if the planet has water.  We don't know if the planet has an atmosphere.  It's gravity is strong enough that it could easily have both of these, like the Earth.  But because we haven't seen the planet, we cannot be certain.

Likewise, we don't know if there is life on the planet.  We don't even know if the weather is right for life.  All we really do know is that, if we were to magically replace the planet with the Earth, the life on our planet would likely survive.

So, in short, astronomers are discovering more and more small planets around other stars.  This planet could be a lot like Earth, and it could be hospitable for life.  But it also could be very different from Earth, and completely devoid of places where life could exist, let alone life itself.  We still have a long way to go until we can claim to have found a truly Earth-like planet, but this discovery brings us much closer.

There is also a video of the press briefing announcing the planet's discovery.

Friday, September 24, 2010

Stumbling out of the gate

Yes, it has been very quiet on this blog lately.  But, perhaps to your chagrin, I am not gone forever.  I've just been completely swamped with my new teaching responsibilities. 

I knew that teaching was hard work, but it is amazing how much time I can put into preparing a class and still feel unprepared.  I'm behind on grading, I need to be preparing exams, and I'm wondering if I am getting anything through to my students.  So, from what I can tell from my colleagues' experiences, I'm having a fairly normal first semester.

I feel for my students, as I've had a few stumbles along the way.  One of the topics I covered in the introductory astronomy class went over like a lead balloon (actually, I think a lead balloon would do better).  At the end of the unit, I found myself asking, "why did I think this was important?", and I can't give a good answer.  So, next time that unit is out, but my current students had to suffer through it.

A couple of weeks ago, I had students measuring angles using their fingers, fists, and hands.  We measured the height of a couple of buildings this way.  It's a time-honored method, and, I thought, fairly simple.  But there were problems in the materials and I hadn't actually done the lab myself, so it went poorly.  In fact, the students nearly revolted.  But this week's lab went much better (I tried it myself first!), so I'm learning.

I've also learned an important lesson, and I think it will prove much more important than which topics I should avoid or which labs I should and shouldn't use.  That lesson is the importance of being confident and projecting that confidence.  In the lectures where I get flustered and let that show, my students pay less attention and don't grasp the material.  In lectures where I exude confidence about my material, I can sense that the students have come along for the ride.  For me, the trick will be to remember to project confidence when, in my opinion, things are going poorly. 

In the meantime, I've fallen behind on astronomy news.  I was surprised the other day by the news that Jupiter was at its closest to Earth in 47 years (not by much, but still a cool factoid).  I have a few months of professional journal reading to catch up on.  But I'll get there. Every day, in every way, I'm getting better and better.

Friday, September 03, 2010

First week of classes done.

I've survived my first week as a real astronomy professor this week, but just barely.  Thank goodness for a long weekend.

Two weeks ago, I started my new position as an assistant professor at Texas A&M University - Commerce, a part of the A&M system located about 70 miles northeast of Dallas.  Classes started on Monday, so there was not a lot of time to settle in to my new digs before I started teaching.  My office is a mess.  Half of my belongings are in boxes, and the other half are strewn haphazardly across my desk.

I'm teaching two classes this fall: introductory astronomy and introductory physics for science majors.  The university has a planetarium, which is great for showing demos in class.  But I'm still learning to use it, alternately blinding my class by accidentally turning on the floodlights during a demo and then making them ill by pressing a wrong button and starting the simulated night sky spinning out of control at an alarming rate.  I'm also learning on the fly how to construct cogent lectures.  This learning is occurring by trial and error, primarily error.  On the good side, though, I'm including a lot of interactive material, and the class is quickly warming up to the idea.  Research into astronomy education has found that more interaction and less lecturing increases knowledge retention.

The physics course is also proving challenging.  Here the main problem has been finding a style that fits both my comfort zone and the material.  Our first unit has been on measurement: units (kilograms, meters, and seconds), significant figures, and similar topics.  It's pretty dry, and there are no exciting demonstrations.  I'm also learning how to judge the amount of material I can cover during the class time.  Experience will help a lot.  I hope.

Anyway, astronomy is marching on.  I hope to write about some cool discoveries of the past few weeks over the weekend, in between unpacking moving boxes at home and grading several diagnostic exams.  Have a great Labor Day weekend!


Sunday, August 22, 2010

Preparing to teach

I'm preparing to teach my first introductory astronomy course.  During my 9 hour plane ride back to the states yesterday, I worked on outlining the topics I want to cover during the course.

One of my teaching resources contains a list of topics students expect to be covered in an introductory astronomy course, many of which are not covered in most courses and texts.  I figure that I will ask my students what they expect to be covered, and if there is something both popular and appropriate, I'll be sure to work it in somehow.

But I also thought I'd throw open the question to you: What topics would you hope would to be covered in an astronomy course that often are not?  I put a poll on the side of this page.  If your favorite answer is not listed, feel free to add it to the comments below. In case you are unfamiliar with topics often covered, here's a collection of astronomy course syllabi collected by Reggie Hudson at Eckerd College

Friday, August 20, 2010

Looking for planets around white dwarfs



Image Credit: NASA / JPL-Caltech

Today is the final day of the 17th bi-annual European White Dwarf Workshop.  It has been a great meeting, but I am ready to go home.

Many of the talks yesterday and today have focused on a search for planets around white dwarfs.  Since white dwarfs come from stars like the Sun, and since at least 10% of sun-like stars have planets, we would expect that 10% of white dwarfs will have planets.  We think the Jupiter and Saturn will certainly continue to orbit the white dwarf sun several billion years from now.


The problem is that it is hard to find planets around white dwarfs.  Many different methods have been tried (my own collaborators included) but there are no confirmed planets around white dwarfs yet.  Does this mean planets, even those far from a star, cannot survive a red giant?  Or do they  fly off into space when the star makes a planetary nebula?  Or have we just not looked at the right stars?  Or perhaps we aren't looking with the right methods yet?

I would guess that the problem is with our methods.  Back when astronomers were looking for the first transiting planets around sun-like stars, they didn't find any.  Based on numbers alone, it was starting to get a little uncomfortable -- we should have found some planets, but nobody had found any.  Then the astronomers involved tweaked the methods, wrote better computer programs, and took lots more data, and the first transiting planets were found.  Now we find them everywhere, and NASA even launched the Kepler Mission to look for Earth-sized planets by finding transits.

I think the same thing will happen with white dwarfs.  Once the first white dwarf planet is confirmed, smart observers will figure out better ways to get the same result, and we'll start finding planets everywhere.  Maybe even by the next conference in two years!

It is time to pack and head home.  Next week, we'll follow my adventures as a brand-new, first-time professor.  Stay tuned!

Thursday, August 19, 2010

An easy day

video

Wednesday was a fairly easy day, at least mentally, at the white dwarf conference I'm attending in Germany.  We only had a short morning of talks, half of which I skipped out on to do some shopping. 
In the afternoon, 150 white dwarf astronomers boarded buses for a conference excursion to the Swiss city of Schaffhausen and the Rhein Falls.

Wednesday, August 18, 2010

White Dwarf Workshop Day 2: Extreme Physics


Yesterday was the second day of this year's white dwarf workshop.   I gave my presentation yesterday, and it went well.  (In a few weeks, video of the talks will be online here. Just not yet.)

Much of the first half of the day focused on physics.  While a lot of astronomy often may appear to involve describing objects, one of our main goals in astronomy is to understand the physics behind all of the beautiful objects in the sky. 

White dwarfs are a great physics laboratory.  Because white dwarfs can contain as much matter as the sun squeezed into a ball only the size of the Earth, the material is very dense.  It is so dense, in fact, that white dwarfs create forms of matter that do not exist on the Earth.  White dwarfs are one of the few ways to study the physics of these extreme environments.

As I mentioned briefly yesterday, white dwarfs slowly cool over time.  The matter in their cores, which starts off as a dense hot plasma, also cools off.  When it cools enough, the matter changes from a plasma to a solid, in fact a crystal.  Since white dwarfs are made out of carbon, and since on Earth crystalline carbon is also known as "diamond", we often claim that crystallized white dwarfs are true diamonds in the sky.  This is not strictly true, since a polished piece of crystalline white dwarf the size of a normal Earth diamond would weigh several hundred pounds. 

Yesterday, one of the talks focused on crystallization.  Since white dwarfs crystallize from the inside out, you might think it isn't possible to catch white dwarfs in the process of crystallizing.  But as white dwarf material crystallizes, it releases heat.  Most crystals, like ice, do the same thing.  The amount of heat released is small, but when you add up a sun's worth of material, it adds up to a lot of heat.  This release of heat temporarily slows the white dwarf's cooling.

When you look at a group of white dwarfs, you will tend to see a whole bunch of different temperatures, since the individual white dwarfs formed at different times and have therefore been cooling for different times.  This slow down in cooling from crystallizing will cause there to be more white dwarfs at one temperature (the crystallizing temperature) than at other temperatures.  It is sort of like a car hitting the breaks on a busy freeway -- cars will quickly pile up where the first car slowed down, and someone watching from an airplane or helicopter can easily spot the slow down.

When we look at groups of older white dwarfs, we indeed see a pile up at certain temperatures.  The exact temperature of the white dwarf pile up depends on what is crystallizing (carbon and oxygen) and the physics of the crystallization.  And we find that the pile up occurs at a different temperature than the physics theorists predicted!

This finding has made a lot of physicists angry.  Some have claimed that the astronomers have made the measurement incorrectly, because everyone who has calculated the crystallizing temperature agrees on the "right" answer.  But this is science - we test theories with observations.  And if the observations don't fit the theory, and if the observations are done properly, then something must be wrong with the theory.

Some physicists have done the scientifically right thing, which is to go back and look at the theory again.  And they've found that some of the assumptions made in the old calculations were wrong.  For example, the old calculations assumed that the crystallizing material was pure carbon.  But white dwarfs are a mix of carbon and oxygen.  And just like adding salt to water changes the freezing point of water, adding oxygen to carbon changes its freezing point. 

This is good science at work.  The observers test scientific hypotheses, and the theorists re-visit ideas that are proven wrong.  Now it is up to us observers to go back to the white dwarfs, measure the crystallization of even more stars, and more tightly constrain the revised theoretical calculations.

Tuesday, August 17, 2010

White dwarfs, day 1

Yesterday was the first day of the 17th bi-annual European White Dwarf Workshop, a weeklong-conference about white dwarf stars.

White dwarf stars are the slowly-fading embers left behind when most stars exhaust their fuel.  Stars shine due to nuclear reactions in their cores.  They fuse hydrogen atoms to make helium, and then they fuse helium atoms to make carbon and oxygen.  The heaviest (most massive) stars can even fuse carbon and oxygen atoms into still heavier elements, but these stars are rare.

Once a star has fused as many atoms as it can into as heavy of elements as it can, the star swells up into a red giant star (the red giant sun will swell from its current diameter of about 1 million miles into a diameter of about 200 million miles, swallowing Mercury, Venus, and maybe even the Earth in the process).  After spending some time as a red giant, a star will blow off its outer layers in a beautiful planetary nebula, exposing the white-hot nuclear reactor that was its core.  This core, which can contain up to half the mass of the original star, is only about the diameter of the  Earth.   This is what we call a white dwarf.

Because white dwarfs are formed in this way, they are one of the few glimpses we astronomers have into the central nuclear engines that power stars.   So, while you could say that this week is dedicated to studying dead stars, it is more like stellar forensics.

Yesterday one of the topics were white dwarfs with carbon and/or oxygen atmospheres.  I've worked in this field quite a bit, and I was part of the team that discovered that many of these carbon-atmosphere white dwarfs change their brightness.  Yesterday's talks made us wonder if maybe all of the carbon-atmosphere white dwarfs change their brightness.  Every single one of these stars that has been studied in enough detail do indeed vary, which is unheard of in other kinds of white dwarfs.

Today I give my talk.  I'll let you know how it goes.

Friday, August 13, 2010

Greetings from Germany


During the quiet stasis that has been my blog of late, I have packed up my things and moved to a new apartment in the town of Rockwall, Texas, just outside of Dallas.  There I will start my new job next week.  More on that in week or so.
Having been in my new digs for three full days, it was time to pack my suitcase and fly to Germany.  This coming week, the 17th bi-annual Euorpean White Dwarf Workshop will be held in Tübingen, Germany.  Virtually everyone who works on white dwarf stars will be here talking about their research during this conference. 
I missed the last workshop, held in Barcelona in 2008, as I had an observing run with the Keck telescope at the same time.  So it will be nice to reconnect with many colleagues for the first time in four years.
So, dear readers, after two months of near silence from me, you are about to be pounded by a week's worth of white dwarf research news. Thanks for hanging in there.

Tuesday, July 27, 2010

Has Kepler Found hundreds of Earth-like planets?

Update (2pm PDT): As pointed out by Daniel Fischer in the comments, the news articles my post is responding to are poorly-reported rehashes of information that came out in the middle of June.  The numbers in the graph that have led to the news articles seem to have been published publicly in this scientific article; the graph in the Sasselov talk was labeled differently but the data seem to be the same.  I hereby retract all implied and explicit criticism of Dr. Sasselov in the original article and apologize to him and the Kepler team for not doing my research on that side of the issue.  I have crossed those statements out, but leave them in as penance. I stand by my scientific statements.

In the past few hours, many news outlets have posted stories claiming that NASA's Kepler Mission has discovered hundreds of Earth-like planets. Here's a reasonable version of the news posted at SpaceRef.com.

These stories are not based on any (new) official announcement, but rather a talk given by one of the Kepler mission scientists at a meeting in Oxford a few weeks ago.  During the talk, mission scientist Dimitar Sasselov showed a slide giving the number of candidate planets discovered so far by Kepler as a function of their radius, and the Earth-sized planet bar is near 150.

According to Kepler's Twitter feed, the team is formulating an official response to this leak.  I'm not on the team, so I don't know what they will say, but let me make a few guesses as to what you can and cannot take away from this news leak:
  1. These are planet candidates, not confirmed planets.  There are many known astronomical objects that can mimic the signals Kepler is looking for.  It takes lots of follow-up work to rule out these false alarms.  Much of the Kepler team is working hard to rule out these false alarms, and a lot of ground-based telescope time this summer is going into these studies.  I'd be willing to wager that the team has a decent idea on the fraction of their candidates that are false alarms, and it's possible that fraction was figured in to Sasselov's graph.  However, since a proven Earth-sized planet would be a huge score for the Kepler team, and we haven't seen any reviewed articles announcing such a discovery.  To me, that says the team feels there is still more work to be done to prove any given case.
  2. Even if they are real, all we know about the planets is their diameter and how far away they are from their parent star.  Kepler works by looking for a drop in the light from a star caused by a planet orbiting between us and the star.   At first, all we know is what fraction of light is blocked by the planet.  Some simple observations of the parent star (many of which were done before the mission, and some of which are done once a candidate planet is flagged) give us the radius and mass of the parent star.  Geometry then allows us to calculate the radius of the planet, and laws derived by the scientists Johannes Kepler and Isaac Newton then allow us to determine how far away from the star the planet is.  But that's all we can be reasonably certain about at the present, at least for Earth-sized planets.  We can guess at the mass of the planet if we assume it is made of rock, and we can estimate how hot its surface is (though this fails dismally for Venus in our own Solar System), but that's it.  We have no way of knowing if the planet has water, continents, or life.  The planet could be hellish like Venus, barren like Mars, or very hospitable like the Earth.
  3. Any real planets discovered so far are so close to their parent star, they are likely very, very, very inhospitable places.  In order for Kepler to have a strong planet candidate, the mission scientists need to see it go in front of the star at least three times.  Once tells you that something might be happening, twice gives you a guess at the length of the planet's "year", and three times confirms that length of the orbit.  Earth takes one year to go around the sun, and Kepler has only been working for a little over a year.  So a true Earth-like planet will only have made one or, in a few lucky cases, two passes in front of its parent star.  Any Earth-sized planets that have been discovered must be closer to their parent star than the Earth, and probably closer than the planets Mercury and Venus.  That means they will likely be hotter than the Earth, and not capable of supporting life. 
    Now, if the parent star is smaller than the sun, the planet could be closer and yet still have a climate appropriate for life.  But that information is not yet public, so I can't guess at what fraction of these planets may have temperatures similar to the Earth.
  4. The numbers of hundreds of planets are probably right.  This is just an educated guess on my part, but astronomers don't put numbers on slides if they suspect the numbers are wildly wrong.
  5.  I'm glad I'm not Dimitar Sasselov.  Whether or not he had permission from the team to include these slides in his talk, you never want your name attached to an unintentional media frenzy.  And if he didn't have permission, teams like this almost always have members sign contracts listing possible penalties for spilling the beans.
So, in short, the only thing I'd feel comfortable taking away from this furor is that Kepler is finding lots of potential Earth-sized planets.  But these are not confirmed planets, any real planets are likely closer to their parent star than Mercury and Venus are to our sun, and we have absolutely no clue if any of these planets are capable of supporting life, let alone if life actually exists on any of them.  Again, any real planets found by Kepler are Earth-sized planets, and NOT NECESSARILY Earth-like planets. (As I tell my students, underlined, italicized, capitalized and bold print means I absolutely mean what I say, and I think it's important, and it will probably be on a test.)


Monday, July 19, 2010

Why you should be literate in science



The above video is of astrophysicist Neil deGrasse Tyson, director of the Hayden Planetarium, speaking at the World Science Festival earlier this year.  In the video, Dr. Tyson talks about the need for us, as a society and as individuals, to be scientifically literate.   Events over the past few years have shown both how important scientific literacy is and how we suffer (individually and as a group) from the growing lack of scientific literacy.  First, let's define what I mean by "scientific literacy", and then I'll give a few (and by no means exhaustive) examples of its importance to each one of us.

Friday, July 16, 2010

Preparing for a change

Sorry to have been so quiet the last few weeks.  In that time I went to my sister's wedding, went house-hunting, celebrated my own anniversary, celebrated Independence Day, and helped with some of my daughter's various activities.  Tonight I'm taking off again for another wedding.

On top of all of that, I'm preparing for my career shift from postdoctoral researcher to assistant professor.  I'm working on planning the two courses I'll be teaching, and I'm trying to finish up as many research projects as I can.

Between all of that, there hasn't been much time for blogging.  I'll be back soon.

Friday, July 02, 2010

Random neat things in the sky

Today I was working on one of the many projects on which I am dreadfully behind.  Usually that means I just plow through the work as quickly and accurately as I can.  This particular project involves taking deep (very faint) photographs of what, to many astronomers, are large areas of the sky  -- patches about as large as the moon.  These pictures often contain 20,000 or 30,000 galaxies, too many to work on by hand.  So I use automation to measure the position, brightness and color of each galaxy.  I then spot check each data set to make sure the automation worked.

When I spot checked this particular image, I noticed lots of really cool galaxies. So I made a color image from our photographs, and I made cutouts of some of the more interesting things.  For each of the images below, click on them to get a larger view.  And, in case you wonder, the blue and white vertical streaks are artifacts from stars that are so bright they overwhelm the camera.  Even so, these stars are typically 1000 to 10,000 times fainter than the faintest star your eye can see on a dark, crystal-clear night.  All descriptions refer to the picture above them.

Sunday, June 27, 2010

Too Many Planets?


The Kepler Mission satellite
Image Credit: NASA / Kepler Mission / Wendy Stenzel

Two weeks ago, NASA's Kepler Mission to look for Earth-sized planets around other stars released their first 43 days' worth of data.  That's not much, considering the spacecraft has been operating for over a year, but it marks the beginning of the deluge.  Simultaneous with the data, Kepler announced a preliminary list of 306 possible planet candidates.  That's roughly twice as many extrasolar planets as were previously known, if Kepler's list is 100% planets, which it most likely isn't.

Kepler works by looking for transits, when a planet around another star passes between the Earth and that star, blocking part of the star's light.  Here are some pictures of the planets Venus and Mercury in transit across the Sun posted by Williams College.  The big difference is that Venus, Mercury and the Earth are all in orbit around the Sun, while the extrasolar planets found by Kepler are around other stars, perhaps 3000 light years away!  Not every planet will transit its parent star due to geometry, so astronomers have to look at a ton of stars (several hundred thousand in Kepler's case) to find the few planetary systems where the geometry is just right.

At those distances, the star looks just like a point of light, even when viewed by the most powerful human telescopes.  So, instead of looking for a dark spot to slowly pass in front of the star, the Kepler Mission team looks for changes in the amount of light coming from the star.  A big planet like Jupiter blocks about 1% of the light of a star, while an Earth-sized planet will block only one ten-thousandth the light of a star.

Friday, June 25, 2010

Night of the Living Dead Stars



Artists conception of an asteroid being ripped apart by a white dwarf star
Image Credit: NASA / Spitzer / JPL-Caltech

White dwarfs, the slowly cooling remains of stars that have completed their life cycles, often seem to be the zombies of the night sky, devouring anything that happens to stray within their grasp.  In an article that will be appearing in an upcoming issue of the Astrophysical Journal, astronomers Patrick Dufour, Mukremin Kilic and collaborators discuss a recently-discovered white dwarf that seems to have devoured a dwarf planet.  Its name:  "SDSS J073842.56+183509.6" (its nickname: 5877352363341268816. Seriously.)

Tuesday, June 22, 2010

It's summer!

Today is the first day of summer, which makes it a great day to address the most common misconception people have about the universe around us: what causes Earth's seasons?

Most people think they know the answer, and most people are wrong.  So, the chances are good that you think you know why we have seasons, and that you are wrong.  Now don't get angry about being wrong, and don't get defensive.  I'll lead you to the right answer,  I'll never tell a soul that you were wrong, and you can go forth and pretend that you knew all along.  It'll be our secret.


Let's dig in:

Thursday, June 17, 2010

Astro 101: The electromagnetic spectrum


Today, we'll continue through my occasional series on basic astronomy concepts.  Previously, we've discussed the difference between solar systems, star clusters, and galaxies.  We've also discussed telescopes and observatories.  Today we're going to talk about the main way astronomers learn about distant planets, stars, and galaxies: the electromagnetic spectrum.

 Within our Solar System, we can send robots (and maybe, someday, people) to run all kinds of tests.  But even the closest star is still trillions of miles further away than our most distant and speediest robot probes.  To explore other stars and the Universe, we have three choices:
  1.  Electromagnetic radiation ("light").  This is by far the most common and most successful method.
  2.  Gravitational waves.  Gravitational waves are like ripples of gravity propagating through the Universe.  This might be detectable in the not-too-distant future, but for now they have not been definitively detected.
  3.  Cosmic rays.  These are high-energy particles coming from all corners of the Universe.  We can detect these on Earth and in space, but so far it is hard to identify where a particular particle came from (except for the many that come from the sun).

Electromagnetic waves, which I'm just going to call "light" from now on so I don't have to keep typing "electromagnetic", seem to have a range of properties.  Radio waves carry information, microwaves heat our food, infrared light carries heat and allows us to "see in the dark" with night-vision goggles, visible light is at the heart (or eyeball) of one of a human's primary senses, ultraviolet light gives us suntans and skin cancer, X-rays allow us to see inside our bodies, and gamma rays turn us into monstrously strong, large, green humanoids when we get angry (or at least that's what I've been told).

Tuesday, June 15, 2010

Science blogging prize update


Late last week, the 3 Quarks Daily blog announced the finalists for their 2nd annual prize for science blogging.  Alas, I did not not make the cut, but nine thought-provoking blogs did.  If you haven't already, peruse the finalists' work here.  Winners will be announced next week!  Congratulations to all the finalists, and thanks again to my readers who helped propel my entry into the semifinalist round of judging!

Thursday, June 10, 2010

Orbit of an extrasolar planet detected!


The star Beta Pictoris  has long had a fascination for astronomers looking for planets around other stars.  Now astronomers have taken direct pictures of the first confirmed planet around that star.

In 1983, the IRAS infrared telescope discovered a disk of dust around Beta Pictoris, the first time dust had been imaged around a star other than the sun.  This dust disk has been well-studied since that time.  For example, the Hubble Space Telescope looked at the disk and found there were multiple disks, as you might expect if one or more Jupiter-sized or larger planets were tugging on the dust as they orbited the star. 

In 2003, European astronomers used the VLT telescope in Chile along with adaptive optics (which allow one to see sharper) to look at the dust disk.  A re-analysis of those images in 2008 found a small dot of light on one side of the star.  The dot was roughly how bright we'd expect a planet to be, but it was also quite possible that the dot was another star that happened to lie along the same line of sight.  This possibility has burned planet hunters before.

The way to tell if the dot was a planet is to look again later.  The star Beta Pictoris slowly moves across the sky because it actually is moving relative to the sun.  Other stars appear to move, too, but at different rates and in different directions, because they are all moving in their own orbits around the galaxy.  We call this movement "proper motion".  Stars and planets that are related to one another, like binary stars, will have the same proper motion.  So, if we see two dots move together, we can be confident that they are related.

Tuesday, June 08, 2010

Thanks for the votes!

2010 3 Quarks Daily Science Prize Semifinalist

This is a very heartfelt "thank you" to all who voted for my post at the 3 Quarks Daily 2010 prize for science blogging.  I finished in the top 20, qualifying me for the next round of judging!  Now we'll just see how the judges feel I stack up against the competition.

If you haven't already, consider taking time to read blog posts by the other semifinalists.  The blogs cover a wide spectrum of science.

Thanks again for your votes of confidence!

Monday, June 07, 2010

Watch a falling star (on Jupiter)



Last week, the planet Jupiter was hit yet again again by a small asteroid.  This time, the impact was caught on video by amateur astronomer Anthony Wesley, and the impact was confirmed by a second observer, Christopher Go (see June 3), at a different site.  The different site confirms that the flash was not caused by something in the telescope, camera, or sky above Wesley's setup.  This is cool stuff, and many kudos are due to both amateurs.  Even more impressive is that this was Wesley's second impact on Jupiter; he was the first to report a dark spot on Jupiter last year that. Analysis of that spot, imaged by the newly-refurbished Hubble Space Telescope, found that the spot was almost certainly caused by an asteroid and not a comet.  Prior to these two events, the only known impact of which I'm aware was the spectacular crash of the comet Shoemaker-Levy 9.

So, why the recent activity on Jupiter?  Are we witnessing the vanguard of an approaching asteroid armada bent on raining destruction on the Solar System?

Vote today (and for me!)

Today is the last day of voting in the 3 Quarks Daily 2010 prize for science blogging.  If you haven't done so already, please head over there and vote for me (only one vote per person, please)!

I appreciate your votes of confidence, and a very big thank you to those of you who've already voted.

You can read more about the prize here, and visit 3 Quarks Daily often for an eclectic mix of highbrow blogging.

Saturday, June 05, 2010

Congratulations, Ian!


Yesterday saw another graduate student join the ranks of PhD astronomers.  Ian Roederer, a graduate student in the Department of Astronomy at the University of Texas, successfully defended his dissertation.

Dr. Roederer works on metal-poor stars, which are the oldest known stars in the galaxy.  In the Big Bang, the elements hydrogen, helium and the tiniest amounts of lithium and beryllium were created.  Every other element, carbon, oxygen, aluminum, iron, silver, gold,  and so on, has been made in stars since then.  Some of these elements are made by nuclear fusion during a star's life, some are made by supernova explosions, and some by rare nuclear reactions in red giant stars.  Some elements, like iron, can be made in more than one of these processes.  Others can only be made by one process.

Friday, June 04, 2010

Prizes, prizes everywhere (and how you can help me win one)

Everybody likes to win prizes.  In the past few days, a few major astronomy award winners have been announced.  Also, voting has opened for an award on science blogging, and I want to win!

Let's start with the science blogging contest.  As I mentioned last week, the blog at 3 Quarks Daily is holding their second annual prize for science blog writing.  The first part of the contest, nominations, is closed.  Now it is time for the public (i.e., you) to vote on the best blog writing.  The top 20 vote-getters will then be judged by the 3 Quarks editors, who will pare the list to 6 to 9 finalists, with the winners chosen by Professor Richard Dawkins.  The three winners get cash prizes!

So, head on over to see the list of nominees for the science blogging award, and then vote for me! (Or, if you must, someone else.)  Note that you may only vote once, so rather than breaking the rules, please convince your friends and neighbors to vote for me, too.  I promise to spend any award money on science education (except I will treat myself to one deluxe caffeinated beverage in celebration).

Voting ends on 11:59pm EDT on June 7, so head over there and vote for me today! Now, before you forget!

Alright, now on to recent astronomy award winners:

The 2010 Gruber Prize for Cosmology goes to Professor Charles Steidel.  The Gruber Cosmology Prize is an award co-sponsored by the Peter and Patricia Gruber Foundation and the International Astronomical Union.  The prize is one of the few major awards devoted specifically to astronomy research, and is akin to the Nobel Prize in prestige among the community (astronomers can win the Nobel Prize in Physics if their work relates to fundamental physics, but most astronomy lies outside this interpretation).

Steidel has led many of the pioneering observations of galaxies in the very early Universe.  He and his collaborators developed some novel and efficient techniques for picking the most distant galaxies out of the sea of faint fuzzy galaxies visible from staring with a telescope.  The further away we look in the Universe is also the further back in time we are looking, so studying the most distant galaxies also means studying the youngest galaxies.  This work is very interesting, very clever, very important, and well-deserving of this prestigious award!

The 2010 Kavli Prize in Astrophysics was awarded to Jerry Nelson, Roger Angel, and Raymond Wilson.  The Kavli Prizes are as prestigious as the Gruber Prize.  This year's recipients are all noted for their work in telescope and optical design, work that has resulted in the largest optical telescopes in the world and, in the next decade, telescopes as large as 30 to 42 meters in diameter!  You can read about their individual contributions here.  I have obtained volumes of exquisite data from telescopes using the various technologies acknowledged in this award, and so I heartily agree that these recipients are highly deserving!

Using the Universe's largest telescopes

A gravitational lens and its surroundings

Image Credit: K. Williams / CTIO
Astronomers often suffer from a disease we call "aperture envy".  The astronomer with the smaller telescope is often jealous of the astronomer with a larger telescope.  This is because larger telescopes collect more light, allowing you to see fainter (which often means further).

I've had the luxury of using many of the world's largest optical light telescopes, which has allowed me to look at some pretty faint things, both near and far.  But the size of optical telescopes is limited by the size of the glass that makes up its mirror.  The largest telescopes currently operating have a diameter of 10 meters (33 feet), and in the next decade telescopes with mirrors 30 meters (100 feet) across will be built.

But suppose that instead of a measly 10 or 30 meters of telescope, imagine we had a telescope with a diameter of 1021 meters, or 100,000 light-years. 

Thursday, May 27, 2010

Shameless self-promotion

The folks over at the 3 Quarks Daily blog have opened nominations for their second annual prize in science for the best blog writing.   I've self-nominated one of my better-reviewed posts, but if you'd like to nominate any other posts of mine (or from any other science blogger), please go to their announcement of the contest and post the permalink  in the comments section. In particular, make sure the post was written on or after May 24, 2009, and make all nominations before May 31.

Here are the contest details, copied word-for-word from the contest site.  Again, post any nominations on their announcement page, not here!  Thanks in advance!

The winners of the science prize will be announced on June 21, 2010. Here's the schedule:
May 24, 2010:
  • The nominations are opened. Please nominate your favorite science blog entry by placing the URL for the blog post (the permalink) in the comments section of this post. You may also add a brief comment describing the entry and saying why you think it should win.
  • Blog posts longer than 4,000 words are not eligible.
  • Each person can only nominate one blog post.
  • Entries must be in English.
  • The editors of 3QD reserve the right to reject entries that we feel are not appropriate.
  • The blog entry may not be more than a year old. In other words, it must have been written after May 23, 2009.
  • You may also nominate your own entry from your own or a group blog (and we encourage you to).
  • Guest columnists at 3 Quarks Daily are also eligible to be nominated, and may also nominate themselves if they wish.
  • Nominations are limited to the first 200 entries.
  • Prize money must be claimed within a month of the announcement of winners.
  • You may also comment here on our prizes themselves, of course!
May 31, 2010
  • The nominating process will end at 11:59 PM (NYC time) of this date.
  • The public voting will be opened immediately afterwards.
June 7, 2010
  • Public voting ends at 11:59 PM (NYC time).
June 21, 2010
  • The winners are announced.

Monday, May 24, 2010

A wacky set of planets


Today, astronomers from the University of Texas at Austin announced some exciting new findings about a solar system 44 light-years from Earth.  They used the Hubble Space Telescope to study the family of planets around the star upsilon Andromedae, and their results raise the question as to what a "normal" system of planets is.  The answer to this question has important consequences for the search for other Earths and life on other planets.

Let's start by reviewing our own Solar System.  In our Solar System, all eight planets orbit the sun in nearly circular paths, and all of those paths line up with each other and with the sun's equator.  It's easier to describe with drawings.  Here's a schematic of what our Solar System would look like if you were out in space over the sun's north pole and looking down:

Image Credit: NASA/Caltech


Recognizing Bad Science Part 1


This is the first part of what will be an occasional series on recognizing bad or poor science. 

One of the aspects of astronomy that makes it so fun is that there are so many weird and wonderful things in the cosmos, from black holes to the Big Bang.  Unfortunately, this vast zoo of the unexpected and unknown has resulted in lots of unscientific and unsupported claims.  If you are interested in the Universe but don't have the time to spend learning advanced physics and math, how can you separate good science from bad science and pseudoscience?

Thankfully, there are some basic criteria that just about anyone can learn to apply that will help.  In this new occasional series, I'll outline some of the easier criteria to apply.  Tonight we start with bad science as seen on TV. 

Thursday, May 20, 2010

Moving on up to the East Side (of Texas)


Sorry to have been quiet recently.  I've two excuses.  The first is that I've been working on an entry about recognizing bad science.  This was inspired by a slew of poorly-made astronomy documentaries I saw on TV recently, as well as some websites and comments people have sent me with "science" arguments that are so poorly made, they aren't even wrong -- they're just jibberish.  But despite several hours of writing, re-writing, planning, re-planning, editing, redacting and agonizing, the entry hasn't worked.  There's too much to write for one blog entry.  So, I'm going to try breaking it up into individual points, and we'll see how that goes.

But the second and bigger reason is that I've been focused on finding a job.  The money that pays my salary runs out in August, and as I mentioned back in March, the job market in astronomy is bad and getting worse.  I am therefore very excited and VERY relieved to announce that I've been offered a job, and that I just officially accepted it this afternoon. Starting in August, I'll be an assistant professor in the Department of Physics and Astronomy at Texas A&M University -- Commerce.

TAMU-C is a university in northeast Texas between Dallas and Texarkana.  The department I am joining emphasizes both research and education.  I will have the chance to work with students who are interested in careers in science, as well as future middle- and secondary-school science educators.  The campus hosts a planetarium and associated public outreach.


This will be a new phase of my career, and from this side it looks to be a daunting challenge.  I'll be sure to let you all know how it is going!


Last, a note to my personal friends who read this blog.  I thank you all for the support, help, hints, and options you've given me over the last few years, and especially this year.  I regret that I have not (yet) thanked you personally, and I hope that you do not feel like I've been ignoring your emails and messages.  While I've been fretting over my future, I've invoked the common introvert defense mechanism of crawling into my shell until it all passed. I didn't want to bother y'all with my problems, and I didn't want to admit how completely overwhelmed I've felt.  I did greatly appreciate each and every show of support and offer of advice and help.  I'm starting to emerge from my self-imposed exile now, so I'll be in touch soon. :)

Wednesday, May 12, 2010

More news briefs


I'm back home from last week's working trip to Tucson, and I am working on a new original blog post that I hope to get posted later today.  In the meantime, here are a few astronomical odds and ends:


  • Run away! Run away! A relatively new field of astronomy involves finding objects that are flying away from their site of origin at high speeds, often due to a supernova explosion or a close encounter with another object.  A few days ago, a team using the Hubble Space Telescope and data from two different ground-based telescopes (the Anglo-Australian Telescope and the European Very Large Telescope) announced that they had found a star 90 times that mass of the sun speeding away from R136, a giant star cluster in the Large Magellanic Cloud, one of the Milky Way's companion galaxies.  What I like about this story is not just the interesting object, but also that the finding illustrates how a lot of astronomy discoveries are made.  The researchers brought together data taken from four different cameras on three different telescopes, and much of those data were taken for unrelated projects.  So, thanks to a little luck and a lot of data sharing, the most massive runaway star yet known has been discovered.
    The other runaway object in the news is what could be a black hole that has been shot out of a nearby galaxy during the merger of two black holes.  Or it could be a somewhat rare type of supernova.  Or it could be a normal-sized black hole that is rapidly eating material from a very bright companion star.  Or it could be the chance alignment of a supermassive black hole in the very distant universe (which is cool but not rare) with a nearby galaxy.  What I don't like about this article is that a little extra data could have narrowed the possibilities quite a bit.  Maybe the astronomers were not able to get more data, or maybe they were worried that someone else was working on the same object, or maybe the graduate student who was writing the paper had some academic deadline to meet.  I fully understand each of these concerns, but the result is a lot of conjecture.
  • Carnival of Space #153  It's a new week, which means a new edition (number 153, to be exact) of the Carnival of Space, a collection of links to some of the most interesting astronomy and space-related blog posts of the past week from across the Internet.  This week, it is being hosted at Cumbrian Sky.  Be sure to have your red-blue 3D glasses handy.
  • Staff appreciation, astronomy style The University of Texas at Austin celebrated Staff Appreciation Week last week.  They led of the week by honoring Lara Eakins, one of the indispensable staff members in the Department of Astronomy.  Lara helps out with undergraduate education, troubleshoots media problems in classrooms, and leads campus star parties and tours of our facilities for many visiting groups.  Nary a week goes by without several Lara-led groups of excited, twittering elementary school children walking past my office door on their way to see our rooftop telescopes.  Way to go, Lara, on a much-deserved honor!

Tuesday, May 04, 2010

Odds and Ends: Tucson edition


This week I am in Tucson, visiting collaborators at Steward Observatory.  We are working on some fairly technical and involved issues, so I won't try and describe it here quite yet.  And, since I'm here to work on those tricky issues, I won't have a lot of time for blogging.  So, in the meantime, here are some short tidbits:

  • Catch up on some of the best of last week's blogs with the 152nd edition of the Carnival of Space, hosted this week by Ryan at the Martian Chronicles.
  • Last week, in the Discovery Channel's new series Into the Universe with Stephen Hawking, Stephen Hawking warned that we may not want to try and communicate with extraterrestrials, as they might come here to kill us all and steal our resources.  It should be noted that Hawking is not the first person to suggest this; I've heard this argument many times.  I think Hawking's point, that space-faring aliens would be so advanced that they may not respect us as an intelligent species, is quite possible, especially when we look at human history.    Universe Today has posted an interview that with Hayden Planetarium director Neil deGrasse Tyson that appeared on CNN where Dr. Tyson discusses Hawking's opinion from a sociological standpoint.  He also mentions the cold, honest truth: we have no idea what an alien intelligence would be like.
  • However, while we may not need to fear aliens, we may need to fear black holes.  And not tiny black holes like the Large Hadron Collider won't make, we're talking black holes with millions to billions of times the mass of the sun.
  • I must be scowling when I go in to restaurants and so be placed in the angry section of the restaurant.  Yesterday at a Cracker Barrel in Goodyear, Arizona, a couple of men at the table next to me were making horribly misogynistic comments.  One of the men even refused to use feminine pronouns to refer to women.  It was very uncomfortable to listen to; thank goodness they finished their meal shortly after I arrived.    Today, at Tucson's El Charro, a  guy at the next table were laughing about how his dad used to mess with a "flaming liberal *$#%#@ astronomy professor" by training lights on the telescope as often as possible.  Seriously.   And this guy found it uproariously funny -- I think that's just kinda weird.
  • Speaking of weird, The Onion reports that scientists have found that dinosaurs aren't extinct; they're just hiding.  I thought there must be something lurking in the shadows.


Tuesday, April 27, 2010

Maybe we should have been monitoring volcanoes after all

Icelandic volcano eruption complete with ash lava and lightning
Flying an airplane into volcanic ash is probably a bad idea. 
Image Credit: Marco Fulle (Stromboli Online)/ Astronomy Picture of the Day

One year ago, volcano monitoring was put forward as an example of wasteful government spending by a prominent politician.  Never mind that the amount of money we are talking, $15.2 million dollars, is only one thousandth of one percent of the federal budget deficit, let's come forward in time a year to the eruption of Iceland's Eyjafjallajökull volcano.  Ash from this volcanic eruption grounded airplanes across Europe, costing airlines nearly two billion dollars.

Why were so many airplanes grounded?  Volcanic ash harms airplane engines.  This page from Boeing describes many of the near-disasters caused by volcanic ash.  We aren't talking about a single incident, but several serious situaitons.  So, when ash from the volcano drifted over Europe, flights were grounded to prevent potential crashes from ash damage.  Now that the ash danger has abated, the finger pointing has begun.  Airlines are blaming governments for being to cautious, governments are blaming airlines for being to risky, and travelers are stuck in the middle with the unexpected costs of an extra week or two of "vacation", plus hassles of trying to get home. 

One of the big reasons for this calamity is that we don't have good, hard, scientific data on what types of ash conditions are dangerous.  Certainly flying right through the eruption column would be deadly, and flying in clear air is safe.  So where is the dividing line?

Monday, April 26, 2010

Earthquakes, volcanoes, global warming, and bad science

The number of large earthquakes per year is not increasing


It seems like there have been a lot of big earthquakes this year.  Today another fairly large quake, magnitude 6.5, occurred off the coast of Taiwan.  Back in March, I blogged about the possible connections between the large earthquakes this year, the upshot being that it may be possible for one large earthquake to trigger another large earthquake, but it is nearly impossible to prove that any one giant earthquake was triggered by another, the exception being earthquakes on the same fault system.

But are there more earthquakes than normal this year?  Geologists keep answering with a resounding "NO!" but most lay people don't believe the geologists.  This seems silly, in that geologists who study earthquakes have saved millions of lives, perhaps in this year alone, by studying fault systems, earthquake probabilities, and building codes.  And it is EASY for anybody to check what the geologists are saying!

Saturday, April 24, 2010

Happy 20th Birthday, Hubble!


Hubble Space Telescope celebrates its twentieth birthday

20 years ago today, the Hubble Space Telescope was launched on board the space shuttle Discovery, opening a new era in astronomy.  Thanks to the efforts of dozens of astronauts, hundreds of dedicated engineers and astronomers, and millions of interested people around the world, Hubble is still going strong at the forefront of astronomy and science!  Happy birthday, Hubble!

Thursday, April 22, 2010

A Cataclysmic Variable in the Field of the Kepler Mission

The field of stars with our new-found cataclysmic variable star

In September of 2008, I was sitting at the controls of the McDonald Observatory 2.1-meter Struve Telescope.  I was there to help some of my colleagues who work on a team associated with NASA's Kepler Mission.  This team, the Kepler Astroseismic Science Consortium, isn't on the lookout for planets.  They are studying the stars themselves, looking for variations in the light from stars caused by sound waves in the star.  The study of these sound waves, known as asteroseismology, allows astronomers to probe the interior structure of a star, just like geologists use seismic waves from earthquakes to study the interior of the Earth.

My specific goal at the telescope was to look for pulsating white dwarfs.  While around a hundred pulsating white dwarfs are known in the sky, none are known in the patch of sky where the Kepler mission stares.  I had a long list of candidates, some that I chose, and some that our European collaborators selected.  One of the stars selected by Viennese astronomer Gerald Handler and his collaborators,  the star in the center of the picture above, had been observed with the Telescopio Nazionale Galileo in the Canary Islands, and looked "interesting".

Wednesday, April 21, 2010

Congratulations Dr. Sean!

Dr. Sean Couch and his wife Theresa
Photo Credit: Emily Bartlett
On Monday, the astronomy community grew as University of Texas graduate student Sean Couch earned his PhD by successfully defending his doctoral thesis.  Dr. Couch finished his PhD in just four years, which is a good year faster than the average.  As you might guess, speed isn't the important factor, it is the quality of the dissertation and the student.  And in both of these cases, Sean is also wildly successful.

I got to know Sean when I taught a course in observing techniques for graduate students three summers ago.  Although he is a theorist, Sean dared to take the course, and he managed not to break any telescopes.  He even successfully took some images of red supergiant stars and found that they were varying in brightness for reasons that we didn't understand at the time (I've since found that this behavior was known, though not well understood).  I later learned that this project, which he developed, was heavily assisted by some of the other graduate students -- Sean's original idea was to look at the star Betelgeuse, which is so bright that it would have burned out our camera, and which is not visible during the summer when we had use of the telescopes.  So perhaps it is best that Sean stuck with theory.

Sean's dissertation involves computer simulations of supernovae, or exploding stars.   Modeling supernovae on a computer is very difficult.  The stars that explode are very large, sometimes as big as Jupiter's orbit, or nearly 200 million miles across.  But the initial explosion takes place in the central hundred miles or so of the star, and the nuclear reactions that power the supernova take place on an atomic scale.   Even the powerful Texas Ranger supercomputer that Sean used for some of his work cannot precisely simulate all the parts of an exploding star, so the models have to be simplified.  As time goes on and computers become more and more capable of performing fast calculations, the models are made more complex.

Wednesday, April 14, 2010

Odds and Ends, April edition

I'm literally sitting in a fog at the observatory, so I have lots of time to think up some amazing new blog post.  Instead, I'm working on a wish list for funding and tracking down equipment troubles.  So, here are some links to keep you busy reading for some time.


  • Forty years ago yesterday, an oxygen tank exploded on board the Apollo 13 service module, threatening the lives of three astronauts and beginning a saga that saw one of the greatest achievements of U.S. space exploration.  In honor of this anniversary, Universe Today is running a multi-part story called "13 Things That Saved Apollo 13".  Five installments have been posted so far; go to the Universe Today main page or follow their Twitter feed to find the newest installments, or just search for tag "Apollo 13".
  • While you are following timelines of historical events, why not  follow the Cascades Volcano Observatory website as it remembers the 30th anniversary of the eruption of Mount St. Helens; you can read what happened today 30 years ago through May 18.  The eruption of Mount St. Helens is one of the earliest news events I remember; I was 6 years old at the time.
  • Universe Today also has a nice story on "Mitch's Mystery Star" that prominently features a couple of my friends and colleagues who pitched in to help explain a very odd-looking spectrum of a star (which ends up being a white dwarf).
  • If you still need more reading material, make your way over to Starry Critters for this week's Carnival of Space, a weekly compendium of interesting astronomy stories floating around the blogosphere.
  • Need a good outing for a rainy April day?  If you live near an IMAX theater, go see their new Hubble 3D movie.  I've heard it's great, and I intend to go as soon as I can get to an IMAX theater.  See the most recent Hubble repair mission in 3D, and also some of Hubble's best pictures (with 3D effects artificially added to Hubble's 2D images).

Monday, April 12, 2010

Light from a distant black hole pierces the Milky Way






Video credit: University of Michigan / Boston University / Cosmovision

We went looking for a small black hole in our neighborhood, maybe a few hundred light-years away, and instead we found a supermassive black hole nearly 7 billion light-years away.  Sometimes astronomy can be that way...

Saturday, April 10, 2010

Twinkle, twinkle, supergiant star

I am back at McDonald Observatory for another observing run, seven nights of staring at the stars.  So of course the weather forecast is for unsettled weather, with numerous weather fronts and troughs passing through.

Tonight started cloudy, but it rapidly cleared as trough number 1 passed through (A trough is a weather feature, like a cold front or a warm front.  This trough had no marked temperature difference here at ground level).   As I went out to marvel at the suddenly star-strewn sky, I noticed that the stars were twinkling furiously, especially those that were setting.  The familiar bright stars of winter, including Sirius (the brightest star in the sky), the twins Castor and Pollux, Capella, and the red supergiant star Betelgeuse were flashing, changing colors, and even briefly winking out almost completely before reappearing with a brilliant flash.

Anyone who has looked at the night sky has seen twinkling stars.  The twinkling we see is not an actual change in the star, but twinkling due to our atmosphere.  Our atmosphere bends light, and if the atmosphere is not perfectly steady, the light from a star will get bent this way and that way.  Sometimes it is bent away from the viewer (causing the star to get fainter), sometimes it is bent toward the viewer, causing the star to get brighter.  This bending of light also depends on the color of the light, so sometimes the blue light from a star is bent away from us while the red light is bent toward us, and vice-versa.  This causes the stars to appear to flash different colors.

This phenomenon is really quite fun to watch.  The star Betelgeuse, which normally shines with a ruddy red color, was dancing to and fro, sometimes appearing steely white, and sometimes it was a bright crimson.  The normally brilliant white star Sirius was rarely white, flashing all colors of the rainbow.

Amid all these wildly dancing stars, there was a bright orange spot that was steady as a rock.  It wasn't changing color, nor was it twinkling.  This was the planet Mars.  Planets rarely twinkle because they are not points of light, but actually appear as disks.  Individual parts of the planet's face do "twinkle", but most of the time the twinkling of different parts of the planet's disk cancel each other out, giving a nice steady glow at a constant color.  However, if the planet is small (like Mercury or Mars when it is far from the Earth), and if the atmosphere is especially turbulent, even planets can twinkle. I've seen it! 

While twinkling stars are cool to look at, they are bad news for the astronomer at the observatory.  We get the best data when the atmosphere is the steadiest, and when the atmosphere is turbulent, we get blurry images.  Because of the weather trough that moved through, the atmosphere is quite turbulent tonight.  This makes the stars twinkle, but it also means my images are quite blurry.  In fact, I've had to skip one of my main targets.  It is so faint that the blurry atmosphere blurred the star out to where I couldn't see it well enough to make useful measurements.  I have backup targets, and hopefully the weather will be better for faint targets tomorrow!