Saturday, March 21, 2015

C'mon now! That's just horrible, man.

Joyful white guys finish ahead of
struggling woman and black man in this university’s catalog

Image in the brochure for the University of North Georgia. In this accurate analogy for the hiring
and tenure process at most HWCUs, we can see a white male, in this case Bill, winning. Those
diversity hires never seem to come in first. The reasons are...complicated.
From an article describing the brouhaha around the image above, via the Facebook Diversity in Astronomy and Physics page:
The University of North Georgia apologized and agreed to stop distributing a course catalog that shows white men winning a race while a woman and black man lag behind.
Because...because of course. Because white, male privilege. Because this is the most honest take on University policy ever distributed by a Historically White College or University (HWCUs as I all them). I hear a picture of the starting line was considered for the brochure, but removed simply because the development office "needed more space for buzz words like 'cross-cutting' and 'diversity'." Fortunately, I was able to locate the infographic showing the starting line:





Monday, March 16, 2015

Research Summary: Searching for binaries in calibration spectra

Today's blog post is by Juliette Becker, a first-year astrophysics graduate student at the University of Michigan working with Prof. Fred Adams on exoplanet dynamics, among other topics. While her work is mostly focused on theoretical astrophysics at the moment, Juliette has extensive experience as an observational astrophysicist from her time as an undergraduate at Caltech (see e.g. Muirhead, Becker et al. 2014). At Caltech, Juliette was also the captain of the track and cross-country teams, setting school records in the 3000 steeple chase, as well as the 6k and 10k distance events. In today's post, she describes her latest paper, which summarizes the work she started with me as an undergrad and saw through to completion, with her paper accepted to ApJS last week. Like reaching the finish line in a 10K event, publishing cutting-edge research requires pacing, endurance and patience!

When I was a sophomore at Caltech, I took the introductory astronomy class, Ay20, with Professor John Johnson. His enthusiasm and approachability inspired me to ask if I could work on a research project with him during the following summer as part of the Summer Undergraduate Research Fellowship (John was a SURF researcher in 1999!). Not only did he say yes, but he also told me about a really exciting prospect. There were years of calibration spectra for the California Planet Survey sitting unused on disk. The targets are rapidly rotating, extremely hot ($T_{\rm eff} > 9000$~K) B-type stars, which were used as nearly featureless "blackbodies" in the sky to illuminate the spectrometer optics the same way as a program star. 

These calibration spectra had been used to calibrate the radial velocity spectra of smaller target stars, but since the calibrators were rotating so rapidly, there was not much immediate use for them beyond this humble, utilitarian purpose. If someone could extract radial velocity information from these spectra, they could potentially do a search for binary (stellar) companions around these massive rotating stars, as the radial velocity of a star with a companion changes over time as the companion "tugs" its host star around. My first task was to do an order-of-magnitude calculation of the precision attainable from a star spinning at 200 km/s. I found that thanks to the high signal-to-noise in these spectra, we could expect a radial velocity precision of greater than 1 km/s, which is more than enough to detect binary companions all the way down to red dwarfs! (This calculation is in the Appendix of my paper). 

The difficulty in extracting these radial velocities arises from the fact that massive, rapidly rotating stars have very few spectral lines, each of which are nearly as broad as the spectrometer's orders (wavelength regions recorded by the spectrograph). While normal CPS targets have thousands of spectral features, a calibrator might have only 10-15 spectral lines. The attached figure taken from our paper for an example of what the comparison looks like for a single spectral order. 
 
To extract the radial velocity data from spectra of rapidly rotating stars, we cannot use traditional methods of fitting the Doppler shift in small chunks of a spectrum and deriving the true radial velocity from a distribution of these shifts. To make maximal use of the few spectral features we have, we fit the entire spectrum – all pixels and orders – simultaneously. This allows the orders without any spectral features to serve as ‘anchor’ orders, setting the continuum level of the fit even as the wide spectral features could otherwise result in an artificially low continuum level.

Our method is described in our paper (details below!), which has been accepted to ApJS and is posted on the arXiv today. As a bonus, not only do we present our functional method for extracting radial velocities from echelle spectra of rapidly rotating stars, but we give absolute radial velocities and rotational velocities ($V\sin{i}$) for each star in our sample (more than 200 stars in all, some of which did not have prior literature measurements).

Here's the preprint of our paper. Enjoy! 

Extracting Radial Velocities of A- and B-type Stars from Echelle Spectrograph Calibration Spectra
Juliette C. Becker, John Asher Johnson, Andrew Vanderburg, Timothy D. Morton


Monday, March 9, 2015

Now that's pretty shameful...

"If we can work out out how to climb into metal birds, slip the bonds of this Earth and soar through the air to visit these territories, we should be able to figure out how the 4 million people who live there can be adequately heard."

So why is it that US citizens in Puerto Rico and Guam can't vote?

Sunday, February 15, 2015

Dealing with Winter

Guest post by Erin



So many recent conversations with friends near and far have begun with some variation of these phrases: "How's your family dealing with the weather?" or "I bet you're really missing California/Hawaii right now?!?!?"

There's often a subtle look of disappointment when John or I report that it's not too bad.  Yes, there's too much snow and nowhere to put it. Yes, it's getting old that the kids have missed 6 days of school in the last month.  But then again, there's a strange comfort in our current inability to control what's falling from the sky and piling up on our streets and sidewalks.  EVERYWHERE!  And our kids are really helping us to make the best of it. This morning as I marveled at the accumulation, my little contrarian MJ informed me that "Mom, that's not really THAT much snow."

When asked what he thinks about all of the weather, OJ said, "You know, I like that we get all of the seasons.  If I want sunshine, I just wait until summer.  In winter, we get snow and it's so much fun to play in the snow, and we never got to do that in California"

Sunday, January 25, 2015

Excerpts and thoughts from MLK's Book


Among the books I'm reading lately is Martin Luther King Jr.'s Where Do We Go From Here, written in 1967, a year before he was assassinated. Reading his words as he wrote them, rather than the platitudes and selective quotes that have passed through the filter of American history, has been extremely enlightening. Reading this book has been at once encouraging (I'm not imagining all of this! I've figured out some things from first principles!) and discouraging (Jeez, all of this written in 1967 applies right now in 2015. Aww...dang.). 

Rather than put down fully formed thoughts on a book I'm only four chapters into, a week after MLK Day I'll take the opportunity to share some excerpts from the book that I've highlighted and pondered. Much of these quotes are from a radical activist who saw the need for reforming America from the roots on up. This is not the moderate, friendly, savior-type that we're taught about in school. MLK was a revolutionary who drew the full attention of the FBI because what he proposed was no salve. Rather, he proposed a complete remaking of a fundamentally broken country.

Wednesday, January 14, 2015

Two paths diverged: Why the messages we send to students matter

Today's guest post is by Dr. Renée Hlozek, a Lyman Spitzer Postdoctoral Fellow at Princeton University. Renée hails from South Africa and came to the US via Oxford University in the UK where she earned her PhD (DPhil) in astrophysics as a Rhodes Scholar. She studies cosmology as a theorist working closely with data from large telescope collaborations. She's also an expert in astrostatistics, which is where our interests start to overlap. Renée was inspired to contribute a guest post following my recent missives on race and racism in astronomy from the perspective of a non-US citizen.

The end of the semester is always an emotional time for me. 

It's a time when you prepare your students to take their exams, and try to instill in them the confidence that they need to stay calm, focused and positive. If you are in any way involved in education, you know those last few classes are key to building students up to the final hurdle. It is particularly poignant to me, because I currently teach a class in one of the country's maximum security prisons.

When I first started teaching I was struck by just how much the class was like any other I have taught before; filled with camaraderie, frustration at algebra and the eureka moments when you get something just right. But there is one major difference between the students I teach inside and those I've taught outside of the Department of Corrections.

When I give positive feedback it often appears like the first positive feedback some of my students have ever received. Feedback on the achievement, skill, intelligence and ability of people I don't really know, but who I am connected to through mathematics.

You might be wondering why I chose to write a blog post about this?f

Friday, January 9, 2015

What can you do to counter racism? (part 1)

Here's an example of how you can use your privilege for good, rather than the societal default of racial injustice. Remember, there are no passive roles in structural racism. 


You can also use this video as a focal point for anti-racism discussions at your home or institution. Here's a helpful guide for how to do so.