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!

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