Monday, September 2, 2013

A Young Black Scientist Making History!

See correction here (posted 10:45AM EDT Sept, 3)

In the most recent volume of Nature---a high-impact, highly selective general-science journal---there is the usual collection of cutting-edge research articles. There's an article about an ancient ice shell on Saturn's moon Titan. There's another about the genetic sequencing of yeast.

Planetary science and genetics are interesting, but one article in particular really stood out to this astronomer. Its title is An observational correlation between stellar brightness variations and surface gravity (Bastien, Stassun, Basri & Pepper 2013, Nature 500, pp. 427-430). The novel and impactful scientific result is an empirical link between the bulk photometric variability of stars to their surface gravity, a key stellar property previously only measurable from high-resolution spectroscopy or extremely difficult asteroseismic observations. Bastien and collaborators coin the term "flicker" to describe the root-mean-square variability of stellar brightness on 8-hour time scales. Stars with low surface gravity are bigger and "fluffier" and when convective bubbles in their interiors rise and hit their atmospheres, they oscillate with large amplitudes (large flicker). Thus, flicker and surface gravity are related (see figure below). If you can measure a star's flicker, you can measure it's surface gravity.

This finding has some important implications for my own research, and it's yet another groundbreaking result to come out of the NASA Kepler Mission. For an excellent review of the science, check out Chris Faesi's Astrobites article, or the associated Nature News & Views article by Christensen-Dalsgaard (behind a paywall).
"Money plot" from Bastien et al. showing the (anti-)correlation between stellar variability on 8-hour time scales (x-axis) and stellar surface gravity (y-axis). This is enormously valuable for measuring stellar properties. [note that I modified the plot annotations for non-astronomers.]
However, the Bastien et al. paper is huge for another reason. The lead author, Fabienne Bastien, is the first Black female astronomer to ever publish a first-author Nature article (Bolded word added per my correction on my previous claim that she was the first Black astronomer to do this. At least three Black men have done so.). This fact highlights a couple things, one somewhat negative and one positive. On the negative side, why the hell is this record being set in 2013 and not 1985?! It's a commentary on the sad state of diversity (or the lack thereof) in astronomy. As I've written before, it's my goal to see to it that we, as a community, quickly tuck these sorts of records away post haste and move into a future in which there are more than 0.5 Black astro Ph.D.s per year and more than 11 total black astronomy professors in a community of thousands.

Fabienne Bastien, a stellar
Black stellar astrophysicist!
On the positive side, we are making progress on this front. Fabienne is a student in the Fisk-Vanderbilt Bridge Program, run by Prof. Keivan Stassun, and there are more outstanding young astronomers who will be following in Fabienne's footsteps in the near future. The program is a partnership between the HBCU Fisk University and Vanderbilt in which students start by pursuing their Masters degrees at Fisk and then work on their Ph.D. at Vanderbilt. Fabienne will be on the job market this Fall applying for postdoctoral positions, and based on her impressive publication record and standing within the stellar astro community I predict that she'll be lighting up the Rumor Mill next Spring. For those of you in the Boston area, Fabienne will be giving an SSP Seminar talk at the CfA Monday Sept. 16 at 4pm, and visiting Harvard that week.

Also encouraging is that Harvard astronomy admitted a black student into their graduate program this year---the first in ~30 years---and I am looking forward to mentoring him while he's here. Keep an eye on the Harvard astro program as I, and others, work to build a more diverse community and usher in a long awaited sea change in this field. It's my feeling that game-changers like Fabienne and Gibor Basri (her coauthor) are born each year in the Black community. We astronomers do a disservice to our science by not seeking them out, training them and welcoming them into our discipline. It behooves us all to increase inclusion so as to hasten our understanding of the Universe (more minds, more progress) and give back to the greater society, at whose pleasure we serve and study (Black folks fund the NSF and NASA, too).


10 comments:

CosmicBabs said...

Hey John,

I was surprised about the first sentence of your last paragraph: "Also encouraging is that Harvard astronomy admitted a black student into their graduate program this year---the first in ~30 years---" ... do I have to understand that Astro Harvard didn't admit any african american student for 30 years? or that they have been invited to the program and rejected it? or that no black student applied to the program during those years?

Kudos to everyone involved in the Fisk-Vanderbilt Bridge Program, and specially to Fabienne!

Babs

John Asher Johnson said...

Yup, sadly, that is correct. Harvard astro has not admitted a black student in 30 years. The last was Leonard Strachan, who is a solar physicist working in the SAO. I checked with him.

We'll be improving on that number right away...

Kyle Willett said...

Hi John,

I'm curious to know - how did you determine that this was the first-ever Nature article by a black astronomer? Franck Marchis, for example, mentions that he identifies as black and has published multiple Nature articles already. Just wondering about your methodology (and congratulations to Fabienne).

Kyle Willett said...
This comment has been removed by a blog administrator.
Unknown said...

Hello John.
Don't forget about Franck Marchis! He was a postdoc at Berkeley while we were graduate students.

Discovery of the triple asteroidal system 87 Sylvia, Franck Marchis, et. al. Nature, 436, 822-824, August 2005.

A low density of 0.8 g cm-3 for the Trojan binary asteroid 617 Patroclus, Franck Marchis et. al. Nature, 439, 565-567, february 2006.

John Asher Johnson said...

Kyle: Thank you SO much for alerting me to my terrible oversight. I have corrected it here:

Correction

Kyle Willett said...

No problem - very happy that it's not quite as bleak as it seems! Thanks again for posting about this, John.

Keivan Stassun said...

Folks, we've been asked by reporters to differentiate flicker from asteroseismology, so I'll share an analogy that we've been using. Flicker is seeing directly the granulation on the surfaces of the stars, whereas seismology sees the global "ringing" of the stars resulting from granulation and other convective motions. The analogy is a pot of boiling water. Flicker is seeing the roiling of the water, seismology is seeing the vibrations of the pot caused by those roiling motions. The vibrations are a much more accurate way to determine the size and density of the pot, but the roiling motions are much easier to see, and the accuracy is not so bad!

Bryan said...

It is incorrect that Harvard has not admitted a black student to its astronomy PhD program for 30 years. Offers have been made to black students, but have not been taken up. I know this for a fact, having tried to convince at least one black student to accept their offer from Harvard and to work on my projects!

I would expect that students from a minority background who are good enough to get into Harvard also have a huge number of other offers, with some places providing extra incentives to accept.

malfalda said...

John,

You might be interested to know about the Bridge to Ph.D. program at Columbia:

http://academicplanning.columbia.edu/bridge-phd-program-natural-sciences

There have been a number of bridge students in astronomy, and several have gone onto to Ph.D. programs. It will be a few more years before we see how many of these students stay in the field.