For the most part, astronomy doesn’t stop for holidays. At Kitt Peak National Observatory, the only nights we don’t open to observe are Christmas Eve and Christmas. Even then, members of my team are on hand to tend instruments and keep watch over the site so things are ready to go the day after the holiday. This year, my shift happened to fall across the entire Thanksgiving weekend. Fortunately, my wife and daughter were able to come up and spend the holiday with me.
At this time of year, I work long nights. My “day” starts around 3:30pm and I work until about 7am the following morning. On Thanksgiving Day, I walked into work to discover my workstation occupied. If you’ve seen the trailer for my novel The Astronomer’s Crypt you might recognize this as something of a recurring theme in my work life! Al Cabone (the skeleton in the chair) showed up at the telescope a little over a year ago at Halloween time and has become something of a mascot.
We start in the afternoon to allow observers an opportunity to calibrate their data. This Thanksgiving, the early start allowed me a chance to bring my daughter to the telescope. She has a definite interest in the sciences with some thoughts of pursuing astronomy. So, this proved a great opportunity to give her taste of what professional astronomy is like.
During afternoon calibrations, I let her have the operator’s chair to enter some commands and try her hand at moving a 3.5-meter telescope.
After calibrations, we were able to take a break for Thanksgiving dinner. At this time of year, dinner is by necessity brief. We finished calibrations at 4:30pm. I needed to be back before the 5:25pm sunset so we could finish getting the telescope ready for the night. Fortunately, we have a kitchen staff at Kitt Peak and they prepare food for us. So my daughter and I joined my wife at the mountain cafeteria for Thanksgiving dinner.
When I speak to people about my work at the telescope, I sense that people imagine that I get to see numerous awe-inspiring sights in the night sky. In fact, some nights I do. However, some nights, the beauty comes from gaining a deeper understanding than what you see in the usual pretty pictures. On Thanksgiving, our job was to measure the spectra of stars in a couple of clusters to understand their chemical abundances. Now spectra can be very pretty, like this one of the star Arcturus, taken with the Coudé Feed telescope at Kitt Peak.
In that image, the interesting science is contained in the pattern of dark lines scattered among the rainbow colors. Those dark lines, or absorption lines, serve as a kind of fingerprint that tells us about the composition of the star’s atmosphere. We were using a multi-object spectrograph, which allows us to get up to 100 objects at a time. That sounds awesome, and it is. That said, this is what the raw spectra look like when we take them.
Each one of the gray stripes in the image is the spectrum of a different star in the cluster. They don’t look much like that. They’re more interesting when you use a graphics program to plot them.
That plot may not look much like the rainbow image above, but it actually contains as much information. Plotted left to right, this shows the spectrum of a star from blue to red. The downward spikes correspond to the dark lines in the rainbow images. The depth of the lines gives you information about abundances. The position of the lines relative to the light frequency can tell you such information as how fast the star is rotating, how far away it is, or even whether it has planets, all depending on the specific measurements you take.
So, the pictures we take aren’t always like those you see in the press releases on the web. Nevertheless, they do inspire dreams of faraway places and allow us to ferret out hidden information in the night sky. I’m not certain whether my daughter will ultimately choose a career in astronomy, but I am pretty sure we’ve given her something to dream about.