Friday, July 24, 2015

Happy Birthday Vera Rubin!

My friend Ramin Skibba wrote a great blog post about Carnegie astronomer and dark matter pioneer Vera Rubin. Check it out!

Monday, July 20, 2015

A Brief History of Stellar Women Bonus Material

GEEK OUT. The wonderful Dr. Cynthia Hunt, an astronomer and social media guru for Carnegie Astronomy and re-re-discoverer of Pluto, saw a of Cecilia Payne's thesis at the Huntington Library last week and got a couple of quick photos. So cool!

A Brief History of Stellar Women

Tonight I'm observing at a different big telescope, Gemini North at Mauna Kea Observatory, Hawaii. But I wanted to share a great Explainer post by Dr. Amanda Bauer, a PhD Astronomer and Outreach Officer at the Australian Astronomical Observatory, that discusses spectroscopy. She was named one of Australia's "Top 5 Under 40” science researchers and communicators in March of 2015, and has written lots of blog posts about different aspects of astronomy.

This one about spectroscopy caught my interest because 1) it's my craft, too, and 2) it's one of the things in astronomy, and science in general (the basic principles come from physics and chemistry), that I explain most often/enjoy explaining most.

Here's the link. Check it out!

However, there is a bit of history missing from Dr. Bauer's post that is important. Much of what I and MANY astronomers do today for our research -- using spectra to classify and learn about stars -- is thanks to some extremely smart and dedicated women scientists. Here's a bit (er, actually, a rather long bit) of history.

In the early 1900s, the director of Harvard Observatory, Edward Pickering, had a problem similar to many scientists -- too much data and too little time or resources to analyze and understand it all. Pickering wanted to continue the work of astrophotography pioneer Henry Draper, whose great ambition it was to catalog the entire night sky with images and spectra. Unfortunately, Draper died at 45 before he was able to fulfill this ambition, but his wife Anna Mary Palmer donated money to the newly-founded Harvard College Observatory to fund the completion of this monumental survey. Imagine trying to

that could be photographed in the night sky!

So, why would Pickering hire women to help, in a time when women's work was valued even less than they are today? He could pay them less -- 25-35 cents an hour of work six days a week, seven hours a day, below what they would make in clerical work. Thus, Pickering could hire more women workers for the same price as half the number of men, and get more stars classified more quickly. The story also goes that at one point, Pickering became frustrated with his male assistant(s) and declared his maid could do a better job! I guess that was meant to be derogatory towards women, but turns out it was true --Pickering hired his maid at the time, Williamina Fleming, who went on to become the Curator of Astronomical Photographs, the first corporate appointment of a woman at Harvard ever.

Harvard Computers, 1892. Maury third from left, with magnifying glass. Flemming standing at center.

Fleming was responsible for cataloging, indexing, examining, and caring for all of the photographic plates in the Harvard catalog, as well as directing about a dozen other women "Harvard Computers". She examined over 10,000 stars (WHOA) and developed classification system for the stars from A to Q, based on how much hydrogen they showed in their spectra. In 1890 Pickering published the first Henry Draper Catalog.

Around this time, Antonia Maury, the niece of Henry Draper himself, was hired as a Computer. She had studied at the all-women's Vassar College under the first American women to work as a professional astronomer, Maria Mitchell. (Connection: I did my first undergraduate NSF REU at the Maria Mitchell Observatory!) She developed her own classification system for the tens of thousands of spectra, more complex and based on differing line widths (rather than just the presence or absence of lines). Maury's line width classification system (normal 'a', hazy, 'b', sharp, 'c', with intermediate cases) was not appreciated by Pickering at the time, and she left the project for a time. Dorrit Hoffliet, one of the other Computers, noted about Maury, "She was one of the most original thinkers of all the women Pickering employed; but instead of encouraging her attempts at interpreting observations, he was only irritated by her independence and departure from assigned and expected routine." However, Danish astronomer Ejnar Hertzsprung recognized the significance of Maury's different classification when saw that c- and ac-stars were brighter than a- or b-stars. Maury's work contributed greatly to what we know now as the Hertzsprung-Russell diagram, a plot of magnitude and luminosity against temperature that is a cornerstone of stellar evolution and classification today.

Around the same time as Maury joined "Pickering's Women" (ugh, I don't like that), a woman named Annie Jump Cannon also joined. Cannon also came from one of the top colleges for women, Wellesley College, and had studied under another female pioneer in science, Sarah Frances Whiting. Cannon took time off after Wellesley, during which she was stricken with scarlet fever and lost nearly all of her hearing. She returned to school at Radcliffe, near Harvard, and was hired by Pickering as his assistant. Cannon was able to refine the classification systems of Fleming and Maury, reducing the number of categories and rearranging them by temperature, leaving us with the famous OBAFGKM; she also included numbers 1-10 within each category as a finer distinction. Cannon's system was adopted as the standard in 1910 by the International Astronomical Union, and today with only minor changes it is known as the Harvard Spectral Classification.

Today, the American Astronomical Association has an Annie Jump Cannon Award for "outstanding research and promise for future research by a postdoctoral woman researcher." Two of the modern day women astronomers highlighted on this blog have won it -- Alycia Weinberger and Anna Frebel. How inspiring! I hope in the future more Las Campanas Belles will be AJC Award recipients.

Annie Jump Cannon, 1922

A few years before Cannon joined the Harvard Computers, another Radcliffe College alum also started volunteering at Harvard Observatory, working seven years for no pay. Henrietta Swan Leavitt, who also lost her hearing, was a classifier who was specifically tasked with studying "variable stars", whose luminosity (brightness) varied over time. During her career Leavitt discovered over 1200 variable stars, half of *all* known variable stars at the time of her death (WHOA). While studying stars in the Magellanic Clouds, Leavitt noted that a few of the variables showed a pattern -- brighter ones appeared to have longer periods of variation. She determined that these "Cepheid variables" had bright-dim cycle periods that were inversely proportional to their magnitude. By assuming that all the Cepheids within each Magellanic Cloud were about the same distance away, such that their intrinsic brightness could be deduced from their apparent brightness (which depends on distance, and was measured from the photographic plates), Leavitt derived one of the most fundamental relations in astronomy, the period-luminosity relationship. This makes Cepheid variables the first "standard candle" in astronomy, a "rung' on the distance ladder allowing astronomers to measure distances to galaxies too remote for more local measurements of distance (stellar parallax). The later discovery by Edwin Hubble that the universe is expanding was made possible by Leavitt's groundbreaking research. Hubble himself said that Leavitt deserved a Nobel Prize, but she died before her nomination could be considered.

Henrietta Swan Leavitt, not sure what year

Love this workup of an American Girl Doll to resemble Henrietta Swan Leavitt!
A few decades after the Harvard Computers got started, Cecilia Payne-Gaposchkin continued the groundbreaking work in her pursuit of a doctorate at Radcliffe College in his new graduate program in astronomy. She was the first person (let alone woman) to do so! This was made possible by a fellowship to encourage women to study at Harvard Observatory, granted by the then-Director Harlow Shapley. In the time period since the Harvard Computers started classifying star, the science of astrophysics had been born -- the lines in stellar spectra were connected to the same lines observed when different chemical elements on Earth were heated and made to emit light. When Payne arrived at Harvard, some elements like calcium and iron had been identified in stars, since they were the most prominent lines, and it was assumed these were major components stellar composition. Payne inherited Cannon's classification system, thought to be based on stellar temperature. Payne saw the connection between the atomic physics causing spectral lines and the different (high) temperatures in stellar atmospheres. Indian physicist M.N. Saha had recently demonstrated how the ionization of atoms (causing spectral lines) was related to the temperature and pressure in stars. Payne showed that the many differences in the lines of stellar spectra were due in large part to the different atomic ionization states, and hence different temperatures, and *not* to different *amounts* of elements. This seems like a subtle distinction, but it is fundamental and crucial to our understanding of the composition of anything that is not on our planet (and many things that are!). Through her work, Payne discovered that the Sun and other stars are mostly made of hydrogen and helium, not heavier elements, which account for less than 2% of the mass of most stars.

Cecilia Payne-Gaposchkin, not sure what year

Unfortunately, unsurprisingly, Payne's work was considered "clearly impossible" by male professors at the time, and in her thesis, "Stellar Atmospheres, A Contribution to the Observational Study of High Temperature in the Reversing Layers of Stars," she included the statement, that the calculated abundances of hydrogen and helium were "almost certainly not real" to protect her career. Though Princeton Professor Henry Norris Russell did not believe Payne's conclusions at first, he later changed his mind after having derived the same result and publishing it, acknowledging Payne's previous work only briefly in his paper. Russell is still often given credit for this monumental discovery. According to also-famous astronomers Otto Struve and Velta Zeberg, Payne-Gaposchkin's thesis was "undoubtedly the most brilliant Ph.D. thesis ever written in astronomy."

So, there you have it. Spectroscopy as we use it today as astronomers is in large part thanks to the contributions of these, and many more, women who worked passionately, for little or no pay, and were not discouraged by the sexism and discrimination challenges they faced. I find their stories remarkable, and am so thankful for their intrepid character and curious, persistent, brilliant minds.

Resources used to compose this summary:

Friday, July 3, 2015

Good night and Goodbye (with STAMINA!)

Being an astronomer is part of my identity. At a conference I recently attended, I learned how this identity is not always automatically generated with schooling or experiences, and actually needs to be cultivated and reinforced in students, particularly those who are not white cis hetero males in STEM. (Aside: examples of cool programs to check out that are doing this are here and here and here.) Similarly, another part of my identity is being a runner, which also needs to be cultivated and reinforced, and practiced *a lot*. Part of this practice in both astronomy and running is resilience, or stamina. Anyone who has completed a PhD will tell you it takes stamina to get through a graduate program, as I'm sure anyone who has completed a marathon will also tell you. (I'll report back after I run my first marathon in October!)

Similarly, it takes stamina to get through a long observing run. As I went to bed last, this morning, I started to feel a twinge of missing things from home, and a physical tiredness not unlike the 3/4 point during a long run, when I'm not sure I have it in me to finish. But when I awoke seven-ish hours later, and looked out my window to see the brilliant blue sky, cloud free, and stepped outside to feel no wind, I felt energized. I felt like I do during the last mile of a long run, usually in a dehydrated, carb- and electrolyte-starved state, slightly delirious -- I could do this forever! This feels so good! I feel alive! That's how I felt going into our last night observing with PFS on Clay (Magellan II).

And so far, I haven't been disappointed! The conditions have been quiet stable and the seeing good. Not as great as it was the last two nights, when I was on DuPont, but still \leq 0.60'', which is especially good for winter nights.

Seeing measurements on our last night (x-axis is UT).
Notice how the red line is almost always below the blue line?
I even saw the "fw" value get down to 0.39''! Paul did not believe me, although Ian Czekal (who starts tomorrow night and was visiting us tonight) also saw 0.39''; Paul said we were both hallucinating. Well, with the help of LCO staff and weather-site guro Gabriel Prieto, I have the data to prove my right-ness:

This is a copy of a few lines from the input into the plot above:
{"tm":"2015-07-03 00:58:01","el":"66.43","fw":"0.42"},{"tm":"2015-07-03 00:59:02","el":"66.24","fw":"0.41"},{"tm":"2015-07-03 01:02:02","el":"55.89","fw":"0.39"},{"tm":"2015-07-03 01:03:02","el":"55.87","fw":"0.42"},{"tm":"2015-07-03 01:04:01","el":"55.84","fw":"0.42"},{"tm":"2015-07-03 01:05:02","el":"55.82","fw":"0.41"},

"tm" is time, "el" is elevation, and "fw" is the seeing value. See, I was not on drugs, Paul!

At the end of this night, Paul jumps on a bus to get to the airport, leaving me by default as the PFS team member to supervise the instrument de-installation. Jeff of course has a nice manual with detailed instructions, and I will have multiple LCO staff members there to do most of the heavy lifting and moving of the instrument. But I'm still nervous. I am the responsible party. I must ensure the safety of a precious instrument. And I must do this after 12 hours of observing. It's just like a long run -- I have to push through hard to the very end. 

I'm ready!

Another aside: If you also like running and astronomy, check out my friend Michelle, The Running Astronomer.

POST DE-INSTALLATION UPDATE: Well that was terrifying. I felt like I was jumping off a cliff into darkness and had to trust that my parachute would open and I wouldn't die. Except my parachute was me. My mind was swirling the whole time with thoughts questioning my ability, everything I said, every move I made. I felt even worse because I don't speak Spanish, making me even less qualified to be giving directions or supervising. Immediately afterwards I had major negative thoughts.

But...I did it. The instrument was successfully de-installed, and is now resting comfortably in the Magellan auxiliary building, where it began. Nothing broke, nothing went wrong, I did not have to wake Jeff up in the middle of the night (California time) with a panicked phone call. My job is done. And you know what? I think I could do it again, and not be so afraid. 

Aaaaand bed time. Ciao, I'll be back in August!


Wednesday, July 1, 2015

Detective Work

When I'm at Las Campanas Observatory, I like to walk around the mountain for exercise. During the winter it's hard to make time for these walks and still sleep and eat, but I find it's important for my mental well-being. Usually I listen to podcasts while I walk. In the last few days, I've been listening to Gimlet Media's Mystery Show, where Starlee Kine does exactly what it sounds like -- solves mysteries. Today I listened to an episode in which she was reuniting a hand-made, personalized belt buckle to its owner, from whom it had been stolen decades before. The show is a little cheezy at times, but mostly creative and entertaining. It reminds me of when I read the book and saw the movie "Harriet the Spy", and walked around for a few days with a notebook and my "tool belt" of knickknacks, spying on people around my neighborhood. 

Why am I writing about detective work on a blog about observing? Because tonight I am taking a night off from finding planets to play a different kind of detective...Disk Detective, that is. Disk Detective is a Zooniverse project, one of several scientific projects that use citizen scientists to collect and/or analyze HUGE sets of data. You can check out a wide variety and have fun making real contributions to science. Multiple projects in the Zooniverse world have produced papers in professional science journals. Disk Detective pits citizen scientists against images collected from the NASA WISE mission, which surveyed the whole sky in four different infrared wavelengths, to look for signatures of disks of gas and dust hanging out around stars. These disks can be both the birth place and the homes of planets -- the disks can be young, still forming planets, or older, harboring planets or rocky debris like our asteroid belt. A computer is not good at distinguishing these planet-y environments from other celestial objects that emit infrared light, plus computers only look for what they're told to look for. Hence the need for HUMAN eyes to help vet the disk candidates! Watch the video below for a preview.

Once vetted, the Disk Detective team conducts follow-up observations using telescopes around the world to hone in on the best candidates for directly imaging planets (see friends at MagAO), better understand why the disks are shaped/oriented in certain ways, better understand where disks are located in the Galaxy and how they vary in their properties, and ultimately, "help astronomers understand the prospects for life around these stars and distant future of our own solar system." Pretty cool, huh? Tonight and tomorrow night I'm conducting some of these follow-up observations on the 2.5-meter Irénée du Pont Telescope. Until tonight I thought this telescope was named after a woman...but I was wrong. At least I think so. Check out this guy -- Irénée du Pont. Rich, lived right before the telescope was built (1970s), name matches. Could there be another namesake of this eye to the celestial sky? Guess I've got myself a new mystery to solve...

DuPont Telescope, during the day

UPDATE: Steve Shectman informed me that the money for the 100-inch was donated by Crawford Greenewalt and his wife, Margaretta Lammot du Pont, an heir to the du Pont family fortune.  Irenee du Pont was her father.  Crawford was in charge of supplying the graphite (from du Pont) for Fermi's atomic pile in 1942. Later he became President and then Chairman of du Pont, and was also Chairman of the Carnegie Board. Thanks for helping with this mystery, Steve!