Thursday, April 30, 2015

Everything Is Awesome When You Have 0.4'' Seeing

Tonight is my first night of a two night run on MIKE (see previous post), a high-resolution spectrograph on Clay (Magellan II) at the lovely LCO. Last night I pestered/helped entertain Jackie Faherty, another postdoc at DTM who is an avid photographer and tweet-er. You'll hear more from her soon. The weather last night fantastic -- little if any cirrus, low winds, balmy temperatures, and seeing around 0.5'' all night. That means that the area over which the starlight was spread (the "seeing disk") was pretty small. This means that the light was more focused and easier to observe, especially for spectroscopy, which places a slit over the star's image and disperses the light into different wavelengths. Observers who use spectroscopy need a stable, clear atmosphere so that as much of their target's light as possible goes into the slit and is collected by the detector to be processed into SCIENCE results!

I got lucky against tonight and the conditions have been great, with seeing reaching as low at 0.44'' (lower seeing = better) and not going much above 0.65''. One of the many wonderful things about LCO and the Magellan telescopes is the good seeing, better on average (in my experience) than any other observatory I've visited. It made me think of "The Lego Movie" theme song, "Everything is Awesome!", which has the lines:

Everything is awesome
Everything is cool when you're part of a team
Everything is awesome
When we're living our dream
When you have 0.4'' see-ing

As promised, here is a snapshot of the projects I'm observing for on this run. All the projects use high-resolution spectra to measure the chemical abundances of elements in stars. For a good mini lesson about this topic, check out here, and also my friend Natalie's huge database of stellar abundances. 

Giant Planet Host Stars -- Determine the abundances of several key planet-building elements (C, O, Si, and Mg) in a sample of hosts to cool, ~Jupiter-sized planets. The host star chemical abundances will be compared to the bulk metallicity (enrichment) of their planets as determined through interior models of planetary thermal evolution, allowing the best constraints to date on exoplanet interior composition and how this relates to formation environment. Determine C/O ratios in host stars of transiting, hot Jupiter-sized planets to complement the detailed analysis of the exoplanets' atmosphere transmission and emission spectra based on Hubble Space Telescope and Spitzer data. The exoplanet atmosphere and host star C/O ratios will be compared to constrain the planet formation processes in these two systems. Interestingly enough, a paper about this, which is quite relevant to my work, just came out on our public paper arXiv tonight! I'm eager to read it when I'm not so tired.

Planet Host Stars in Binary Systems -- Study known host star binary systems in which one or both stars host planets large-ish exoplanets. It builds on my previous study of another host star binary in a search for the signatures of different types of planet formation on host star abundances. Disentangling how an individual star’s atmosphere is affected by the local or global composition of the disk, the formation of planets, and its broader position in/motion through the Galaxy during its evolution is difficult. However, binary host stars provide a unique and potentially less complicated environment for constraining the magnitude of planet formation effects on host stars, as they are assumed to have experienced similar environments throughout their lives. So the idea is to study pairs of stars that should be chemically identical to see if they're actually chemically different, and if this could be related to formation of (or ejection, or the star "eating") different types of planets.

Solar-type Stellar Companions to Brown Dwarfs -- This is a brand new project comparing brown dwarf abundances to those of their higher-mass companion stars, and will help answer whether directly imaged planets and brown dwarfs are more/less similar to their host stars, shedding light on their formation processes. The C/O ratio is also a diagnostic in this case, to help understand whether brown dwarfs form more like planets or more like stars. My colleagues and I just submitted a new paper on this study, and we're expanding it to more systems and a larger parameter space. We'll see what the referee thinks...usually I like to wait until a paper has been accepted to post it to the public arXiv (where anyone can read and comment on it), but it wasn't totally my decision in this case (I'm not the first author).

Alright, time to do some end-of-the-night calibrations and then get my data reduction with Dan Kelson's MIKE pipeline to see if I need to re-do any targets tomorrow (er...later today)!

Oh, I almost forgot -- this is a blog about women observers at LCO, and today there were four women workin' on the mountain!

From left to right:
Gwen Rudie is a postdoc at Carnegie Observatories, Jackie you'll meet soon, (me), and Katie Morzinski is the Magellan AO Instrument Scientist. The MagAO team are also doing super cool exoplanet-y science and WAY COOL new instrumentation, and you can read all about it on their blog, which helped inspire this blog. Sagan Fellow Jared Males was our expert photographer.

No comments:

Post a Comment