Thursday, January 24, 2008

Beatrice Tinsley

Yesterday, I talked about the results of some black hole studies by Dr. Ramesh Narayan, who is visiting the University of Texas Department of Astronomy as the "Beatrice Tinsley Visiting Professor." Since the story of Beatrice Tinsley is not well known outside the astronomy community, I thought I would tell bits and pieces of it here.

Several people have already written Tinsely's biography on the web, and I have nothing new to add. In summary, Tinsley was born in Englang, grew up in New Zealand, married a physicist, came with him to the University of Texas at Dallas. She earned a PhD from the University of Texas at Austin, but was only given an undistinguished research position at UT Dallas. Tinsley performed ground-breaking research (more on that below), but UT Dallas did not give her a professorship. After a long struggle, she left Texas, divorced, and went to Yale in 1975, where she quickly became one of the most distinguished astronomers in the United States. After only six years, she died from cancer. For more details on the life of Tinsley, you can read this brief article from the American Astronomical Society's Committee on the Status of Women in Astronomy, a biography from the the New Zealand Edge, another detailed biography, or you can even a published biography (if you can find it in print).

Tinsely's research was some of the most influential astronomical research of the times. At the time, little was known about the evolution of galaxies -- how did galaxies form, and how did they change over time?

Galaxies, as you may know, are collections of billions of stars bound together by gravity. The Milky Way is a galaxy; the Andromeda Galaxy is a near-twin of the Milky Way located 2 million light-years away. Both galaxies are spiral galaxies. Further away from us, we find some elliptical galaxies, which look like fuzzy blobs and lack beautiful spiral arms. Moreover, elliptical galaxies are distinctly more yellowish than spiral galaxies, which tend to be quite blue. But it used to be quite a mystery what caused these different shapes and colors.

One of Tinsley's most profound insights was that, since galaxies are made out of billions of stars, we can use what we know about the lives of stars to learn about the history of galaxies. We know that bright, blue stars live only for a few million years, while yellow stars like the sun can live ten billion years. So, a galaxy that is currently blue is forming stars now, while yellow galaxies are not.

While most of the above was known or guessed at when Tinsley was working, she put a great effort into calculating not just how galaxies look today, but how they would look over time, depending on how they formed their stars. A galaxy will look different if all of its stars formed in a big flurry of activity 15 billion years ago than if its stars were formed steadily over fifteen billion years, even if the galaxy is not presently making stars. Tinsley calculated models for dozens of different types of galaxies with many different possible histories for star formation -- a tremendous effort in the days before a powerful computer could sit on everyone's desktop.

At the time Tinsley was doing her work, our view of the Universe was rapidly changing. The Big Bang had only recently been proven, and models of stars were only just beginning to tell us how nuclear reactions in stars produced all of the elements in our Universe. The theory behind the life cycles of stars was solidifying into the basic story we believe today. Tinsley was able to take all of this different information and synthesize it in her work. As telescopes allowed us to look at more and more distant galaxies, her work and methods became the central means for understanding the changes that we saw in galaxies as we looked further and further back in time.

People can (and do) discuss at length the positives and negatives of Beatrice Tinsley's life and personality (read the links in the second paragraph), but there is no denying how, in her short career, Tinsley synthesized a tremendous amount of emerging information to become one of the giants of astronomy in the 20th century. And this is why the University of Texas at Austin and the American Astronomical Society both have awards in her name.


  1. very nice article! i hadnt actually read much about her contributions to astronomy and i'm now enjoying catching up! thanks!

  2. Michelle Witton2:55 PM

    Hello. I can advise that there will be a season of the play "Bright Star" by Stuart Hoar which is about the life and work of Beatrice Tinsley at The Tabard Theatre, 2 Bath Road, Turnham Green from the 9th - 27th November 2010. Performances are Tues - Sunday @ 7.30pm; matinees @ 4pm 20th and 27th November.
    Tickets are £14 and £12 (conc).
    The production is supported by The Royal Astronomical Society. I am one it the play's producers.

  3. Great article, thanks for clarifying background for me. I saw the play Michelle talks about last night and it was very moving. Asked my husband (who's a high-energy physicist, not an astronomer) about her, and he hadn't really heard about her. So not acknowledging fully women's contribution to science is not quite a thing of the past yet...