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Ein Stern ist (nicht ganz) geboren

A (Ful)bright Future

Ein Stern ist (nicht ganz) geboren

Olivia Wilkins

After struggling to get my Stadtanmeldung, apply for my Aufenthaltsgenehmigung (which I am still trying to do), deal with a defekt Waschmaschine, and set up internet in the apartment with only very basic German, I am finally working on the fun stuff: astrochemistry.

At the Universität zu Köln, I am doing laboratory astrophysics, but with a focus on projects of astrochemical research. There may be opportunities to do some observations of interstellar gas clouds, perhaps even with the Radioteleskop Effelsberg, but for now, I am strictly doing spectroscopy of proposed interstellar molecules. While I may not be using my results for astronomy myself, my work could likely be added to the Cologne Database for Molecular Spectroscopy (CDMS), an important resource to astronomers globally; the CDMS is especially important to me because I used it while doing research at the Harvard-Smithsonian Center for Astrophysics (CfA) in summer 2014, which is what inspired me to look to Germany when applying for the Fulbright in the first place! The CDMS, which is managed by members of the Cologne Laboratory Astrophysics Group, is a database of numerous molecules of astronomical interest. The catalog has important pieces of information (i.e. frequency) for identifying molecules detected in space as well as physical parameters (e.g. molecular energy levels) that can be used to calculate abundances.

The Radioteleskop Effelsberg near Bad Münstereifel, Germany (2014)

All of this—identifying molecules in space and figuring out how much of them are out there—can be done by spectroscopy. Spectroscopy, most simply, consists of methods that rely on the interactions of matter, or stuff, with electromagnetic energy, or anything from radio waves to visible light to X-rays. All matter either emits or absorbs energy which can be measured by a spectrometer. Astronomers rely on matter emitting energy, which can then be collected by a telescope, whether it is a radio telescope like the Radioteleskop Effelsberg collecting radio waves or an optical telescope capturing visible light. On the other hand, laboratory astrophysicists and astrochemists usually rely on absorption, which is generally easier to work with in the lab.

The electromagnetic spectrum. Our eyes can see energy in the form of light and color at the small visible range of the spectrum. My interests in astrochemistry rely on lower frequencies such as radio frequencies.

A spectrometer involves a lot of parts (I am only covering the basics here), but is relatively easy to work with once it is set up. First, in order for absorption spectroscopy to work, you need something to be absorbed; this is called a source. In UV-visible spectroscopy, this is something like a lightbulb; in submillimeterwave spectroscopy (what I am doing), we need radio waves. Our source is a synthesizer: a large metal box that looks like it belongs to a computer from the 1970s. The synthesizer produces radio waves that—when running into molecules in our sample—will get absorbed. In order to measure how much of our radio waves are getting absorbed, at the end of our cell (what is holding in our molecules) we have a detector. The detector is then hooked up to a computer on which a program collects all of the information and turns it into a spectrum.

Basic schematic of a spectrometer. Energy (e.g. radio waves) are released from the source and passed through the sample before being measured by a detector.

Okay, that's neat and all, but what am I actually looking at? Now that is where the cool stuff happens!

Basically, for my first project, I am making and looking at the stuff that stars come from.

In the lab, we are able to make plasma at high rotational temperatures (up to 10,000 Kelvin) and thermal temperatures of about 300-330 Kelvin (room temperature is between 290-300 Kelvin). On Earth, we see plasma as lightning or the power behind neon signs; off Earth, plasma is found anywhere from stars to the interstellar medium (ISM). In the lab, I make the ISM type of plasma.

I make the plasma in a long (about 5 m) Pyrex cell that I hold under vacuum. Using some heavy pieces of machinery, including a turbo pump, I evacuate the cell to 0.5 μbar (0.0000005 bar); seeing as standard pressure is just over 1 bar, I'm making the Pyrex cell pretty empty. After the cell is mostly evacuated, I release Argon into the cell and start a discharge that causes the gas to glow. I have successfully made my plasma!

Once my plasma is glowing and appears stable, I add a precursor molecule that then gets blown apart under the interstellar conditions. Its atoms then rearrange to form new molecules that don't even exist on Earth, allowing me to observe molecules that form in space without needing to secure time for telescope observations. What's especially cool is that, while many of the molecules I see are new to me, some of them are ones I identified in summer 2014 when working at the CfA.

Perhaps the most exciting part of my work as a Fulbrighter this year (at least so far) isn't the stellar research opportunity. Rather, the Cologne Laboratory Astrophysics Group is open to me tailoring my year to how and what I want to learn within the realm of astrochemistry. Being able to incorporate what I've already learned as an undergraduate with the abundance of things I am learning in Köln is extremely rewarding, especially because I'm not anyone's lab slave; I'm contributing my own thoughts and exploring my own research interests, and that is... well... pretty out-of-this-world.




The comments in this blog are those solely of the author and are not endorsed by the Fulbright Commission in any way.