Astronomy 94: Exoplanet Research
at the Peter van de Kamp Observatory
Archive of Announcements
Week 14
Wed., May 1: On Thursday at 8pm, we'll have Oscar's, Yousef's, and Sam's presentations on planet formation theory, multiplanet systems and orbital resonances, and tides and ellipsoidal variations, respectively.
Fri., Apr. 26: In next Tuesday's class, we will have presentations by Zack (on signal processing techniques for finding transit candidates) and Oscar (on planet formation theory). OK - Jonathan and Oscar are swapping days; Jonathan's presentation is on infrared measurements of exoplanet atmospheres.
Week 13
Fri., Apr. 26: In next Tuesday's class, we will have presentations by Zack (on signal processing techniques for finding transit candidates) and Oscar (on planet formation theory).
Sat., Apr. 20: In Tuesday's class, we will have presentations by Ariel (on volcanism on exoplanets, and its detectability) and Holden (gravitational microlensing of exoplanets).
Week 12
Mon., Apr. 15: Will we have presentation from Philip (on tidal circularization of exoplanet orbits) and by Kelley (on the concept of the habitable zone and the suitability of exoplanets for life) in class on Tuesday.
Week 11
Mon., Apr. 8: No one has volunteered to give their presentation this week, so we will not have any presentations in class tomorrow. I will however be in the seminar room, where our class usually meets, and ready to show students how to work with our transit data. This meeting is optional; students should come only if they want to analyze some data. Please bring your computer and have AstroImageJ installed and the data I made available for KELT-4 on your computer as well.
Week 10
Mon., Apr. 1: Our first two student presentations will be given in class this Tuesday.
The information posted here about data and data analysis is from last week. Please download the data and download and install the software if you haven't yet. I'll soon post information about the next steps.
Regarding presentations, I'll have feedback for those of you who've written to me recently about your presentations. Please continue to stay in touch with me and let me know if you need any feedback or suggestions if I haven't heard from you recently. Soon I'll be asking you to sign up for presentation slots. Finally, check the assignments selection below for a little information about this week's presentations, including some optional background reading.
Sun., Mar. 24: I have done the photometry on the data that we took last month (recall some sample images). As part of the process, we extract all the source+sky counts in a circular "aperture" centered on the star (and also for other bright stars in the field). Here is a screen shot of the radial profile of KELT-4, with several different apertures indicated. And here is the transit light curve (it got cloudy just as the egress was occurring, unfortunately, but we certainly detected the transit). More on this soon.
Week 9
Sun., Mar. 24: I'd like to have our first student presentation a week from Tuesday.
We'll be talking about the Rossiter-McLaughlin effect in class this week, and looking at some data. I'll have office hours on Monday and also on Tuesday. Please come and talk to me about your research for your presentation.
I have done the photometry on the data that we took last month (recall some sample images). As part of the process, we extract all the source+sky counts in a circular "aperture" centered on the star (and also for other bright stars in the field). Here is a screen shot of the radial profile of KELT-4, with several different apertures indicated. And here is the transit light curve (it got cloudy just as the egress was occurring, unfortunately, but we certainly detected the transit). More on this soon.
Week 8
Sun., Mar. 24: You can review the slides from last week (week 7).
Mon., Mar. 18: Tuesday's class is cancelled. Instead, please spend an extra 75 minutes over the next two days doing research for your presentation.
I have emailed everyone with a response to your initial presentation ideas. I'd like you to follow up on at least some of my suggestions and by the end of the week (by Saturday at noon, the latest) you should email me (at least once) with some thoughts about things you've found that interest you. An upcoming goal will be having a coherent storyline for your presentation, working your way toward an outline.
I will have extra office hours this week (Wednesday and Thursday; see upper right side of this page). I encourage you each to come and let me know what you're thinking about your presentation.
Wed., Mar. 13: Ideas for your project topic are due at the end of the week. Sun., Mar. 17: If you've submitted a project idea, then you should have received a response from me. Get in touch anytime with questions or ideas. Special office hours this week: Wednesday 11:30 - 12:15; 1:15 - 2:00; 4:00 - 5:00; and Thursday 1:30 - 3:00 (and by appointment).
In class on Tuesday, I'll give a presentation on the Rossiter-McLaughlin Effect. update: I'll do this next week, instead.
Week 7
Thu., Feb. 28: We have quite a few talks coming up. They're on theoretical physics - this Friday, and next Wednesday and Friday. Though they don't have to do with exoplanets, it would be great to see you there. Note that next week's talk titles and abstracts are not posted yet.
Over the weekend, I'll send more information about project topics.
I've posted a reading (and viewing) assignment for next week's class, below, in the assignments section. This is intended to sort of wrap-up the first half of the semester, now that you understand the basics of transit and radial-velocity measurements of exoplanet systems.
Also, I've got various things for you to check out, related to items that have come up in class over the past couple of weeks. These include:
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Some sample frames from our KELT-4 observations. See if you can figure out what's what (the file names might help). (Stay tuned for information about software that will enable you to look at the raw images (and change the grayscale, etc.) yourselves, and eventually, to analyze the data.) And, there are lots of interesting links in the "week 6" section of the old assignments page. Some have only recently been posted. Here is that awesome image of Venus transiting the Sun, in which we can see Venus's atmosphere due to its refraction of sunlight. Every evening I get an email with 50 or so new research papers (well, their titles and abstracts, anyway). There are always some exoplanet-relevant papers. Just as an example - you don't have to look at all of these - here are four from Tuesday's "astro-ph" email: the origin of Earth's water, photometric stability in planning space telescope missions, observational effects of planet-planet interactions, ground-based measurement of various compounds in an exoplanet atmosphere. And here are four more from last night's: next-generation transit survey planning, exoplanet atmosphere photochemistry: detecting volcanic gases?, signal processing and error analysis of light curve analysis, can the presence of terrestrial planets be inferred from trends in the chemical abundances of host stars?. These are all pretty interesting seeming, and might motivate you to think a little about presentation topics (though most, if not all, of these papers are pretty narrowly focused, but the topics are all possibly relevant). You can search or browse the astro-ph archive from any of the URLs linked above. |
Week 6
Fri., Feb. 22: We've been doing some observing, but probably won't do any more before class on Tuesday. However, I will reduce our KELT-4 data from Thursday night and share it with you.
Week 5
Mon., Feb. 18: There is no written assignment for you to hand in for tomorrow, but see the assignments page for information about posting a question about the reading prior to class. And also for our next reading assignment.
Also, I've posted the links to the two binary orbit simulators on the right side of the front page.
Fri., Feb. 15: We were able to do a little bit of observing last night. I'll let you all know what I find when I have a chance to reduce the data on the transit of HAT-P-25b. I'm thinking that we might be able to observe again on Sunday. Stay tuned for an email about that possibility.
I am giving the department research colloquium on Wednesday at 4:30 pm. It would be great to see you there if you can make it, although I will not be talking about exoplanets, but rather my main area of interest: X-rays from the stellar winds of massive stars. (Information is at the links below, in the Upcoming Events section.)
We'll be shifting gears in class for the next couple of weeks - talking on parallel tracks about solar system (and by extension, exoplanetary system) properties and formation. And starting to learn some basics of observational astronomy, along with collecting, reducing, and analyzing our own data. For now, see the reading assignment below, which is on the first topic.
Stay tuned for information about student presentations and potential presentation topics.
Finally, some time over the weekend, I will post a few more items on this page -- mostly follow-up from class this past week (e.g. the binary star simulation).
Week 4
Wed., Feb. 13: I'm glad so many of you were able to make it to the observatory on Tuesday night. We'll do some observing again tomorrow (Thursday) night, weather permitting. Likely, the conditions will be about the same as Tuesday -- good enough to observe some things, but too hazy/cloudy to get data with an accuracy of better than 1%. But, maybe we'll get lucky with the weather, in which case we'll observe a transit. If you came on Tuesday night, feel free to come again, but don't feel obligated. If you didn't come on Tuesday, try to come for at least part of the time on Thursday. I'll start observing at 5:15 pm; you can meet me at the observatory then. I'll stay no later than 6:30 pm and at that point we'll decide whether or not to get together again later (depending on the weather).
Sun., Feb. 10: This Tuesday is the monthly public open house at the observatory from 8 pm to 9 pm. I thought we could do some observing as soon as it's over. You should come by a little before 9 pm. However, the weather outlook for Tuesday night is not currently very good. I'd say we have a less than 50% chance of being able to do this. But a greater than 0% chance. Stay tuned for updates. I'm sure not everyone can make it on Tuesday night at 9pm, even if the weather is good. I will therefore schedule some more observing opportunities for later in the week as well.
Week 3
Take a look at the solutions to assignment #1.
At the end of class, I handed out a hand-written list of equations, conversion factors, and constants. I'd recommend you use this sheet, adding important things to it as they come up.
And here are some recent exoplanet news items of interest: The Kepler spacecraft had a problem about two weeks ago. Now they're hopeful it's fixed. And here is an unrelated news article about a method for reconstructing exoplanet surface features via the light that's reflected off them. And on Thursday, an article about habitable zones.
Week 2
The slides from our first class, last week, are now posted.
There's a nice full moon rising right now (the exact full moon happens around 11:30 tonight - Saturday). Go outside and have a look. Notice how the moon is further left (East) than it was earlier in the week, and how it's also more full. The overall brightness of a planet or satellite depends on the relative position of it, of the observer here on the Earth, and of the sun or star illuminating it. This is true of things inside our solar system, and also true of exoplanets. We will see situations in which the reflected light from a large, close-in exoplanet contributes noticeably to the light curve of the star+exoplanet system, and how this contribution changes as a function of the exoplanet's orbital phase -- much like the moon's brightness changes with its orbital phase, from our point of view.
Week 1
Astronomy 94 this semester is an introduction to the exoplanet science that we do with the 24-inch telescope. It will include the background astrophysics of exoplanets, basics of observational astronomy, and the technical aspects of measuring exoplanet transits at our observatory. The class will be offered for 0.5 credits and will have a 75 minute, weekly meeting. There will be reading, homework, and some observing outside of class.
The Peter van de Kamp Observatory on the roof of the science center is now several years old, and used routinely by faculty and students both for education and for research. The research that we carry out there is mostly focused on the burgeoning field of exoplanets - planets orbiting other stars. Twenty years ago, we - humans - knew of no planets outside of our own solar system. In the last two decades, nearly 1000 exoplanets have been discovered.
And for many of them, a surprising array of physical properties can be determined (all without any direct imaging of the exoplanet itself): the planet's radius, mass (and together, its mean density), its orbital properties, and even its atmospheric chemistry and heat transport properties and its orbital alignment with its host star's rotation axis (though these last few can't be measured with our telescope).
Many of these exoplanets can be studied via their transits of their host stars, which temporarily dim the light we see from the star. Doing so requires the ability to measure changes in brightness of less than one percent. We can achieve this level of accuracy at the Peter van de Kamp Observatory, and are currently participating in several collaborations, both to discover new exoplanets (around especially bright stars and around young stars), and to characterize the properties of known exoplanets.
Topics we will cover in this class include:
orbits and how they're determined
transit light curves
properties of known exoplanets
telescopes and detectors
basics of photometric observations
Return to the main class page.
This page is maintained by David Cohen
cohen -at- astro.swarthmore.edu
Last modified: May 6, 2013