What is your favorite exoplanet?
This week, I went around the astronomy department, visiting several members of the EOD group, and asked them that question. While I sometimes post about recent discoveries, I wanted to present "older" planets because they are always worth knowing. Instead of compiling a more random list, I thought that a group of planets which carry personal meaning to my team would be a good starting point. Going from there, I found out why they chose research in this field. So, to learn more about some exoplanets and more about my group, continue reading and find out!
Although not a member of the EOD group, Josh Winn kindly answered my questions in our phone call, the main content of which was covered in an earlier post
. The spin-orbit misalignment expert has a soft spot for HAT-P-7, the first retrograde orbit system. He also likes 55 Cancri e, a transiting component of a five-planet system. The host star is the brightest of any transiting system so far.
Eunkyu, my fellow undergraduate, said she liked HD 80606 b. The planet used to demonstrate the EOD and exoplanets.org
in action in our poster, HD 80606 b is in an orbit of eccentricity 0.934. The eccentricity shows in the radial velocity plot, a feature that grabbed Eunkyu's interest.
Eccentricity ranges from 0 to 1, with 0 indicating a circular orbit. An eccentricity of 0.934 would mean its orbit is something like:
(Watching the "planet" go around makes me think of an amusement park ride.)
For comparison, this is a planet with 0 eccentricity:
Eunkyu also likes that astronomers have detected the planet's secondary eclipse. When the concept of secondary eclipse was introduced to me, HD 80606 b was the example.
Eunkyu explained that she approached Dr. Wright because he gave a presentation on exoplanets during her freshmen seminar. He had shown the histogram of discovered exoplanet numbers throughout the years. I thought of how Dr. Wright had also presented to my freshmen seminar class, but by that time I had already contacted him and began research with the group. But what struck me more was that I had never actually asked how Eunkyu became involved.
When Sharon Wang, one of Dr. Wright's graduate students, came here, she did not specifically aim for exoplanets. It wasn't until Dr. Wright taught their grad seminar, having them read papers and discuss, that she became interested. She is the one responsible for boottran, a crucial program that generates predicted ephemerides for our involvement with TERMS. Her favorite planet also came about because of TERMS. At the end of 2010, she and Dr. Wright began picking random stars with new Keck velocities to fit for a TERMS meeting. A goal for TERMS, represented by "R" for Refinement, is to improve the orbital fit for planets. While refining the orbit of HD 37605 b, they discovered a new planet! In preparation for publication, HD 37605 c, Sharon's favorite planet, is a Jupiter analog, orbiting its host star many astronomical units away. The b component is at only 0.26AU (almost 40 million kilometers) away with a period of 54.2 days. Like other hot Jupiters, the b component seemed to have migrated in, but why hasn't the c component?
Ming Zhao, our post doc, is a fan of Star Wars. But even if someone isn't, it's easy to understand why he picked Kepler-16, the Tatooine-like planet, which orbits a binary star system. With "two suns in the sky," as Ming says, it can get pretty hot.
Planet candidate KOI-13, another planet Ming likes, is quite a high temperature. Ming gave me a number of around 3000K. KOI-13 lies on the boundary between planet and brown dwarf in terms of mass. The host star has a "companion", which is very far away, although as seen from the field of the sky, the angular separation is very small, making it a good scientific calibrator to measure the spectrum of KOI-13 and study its atmosphere. Ming, with an interest in planetary atmospheres, can compare this to the atmospheres of hot Jupiters. Although in the field of explanets now, Ming began in interferometry during his undergraduate years. In graduate school, he worked on using interferometery to detect exoplanets, but it was difficult. Before coming to Penn State, he worked at JPL
for two years. Once here, he still decided to get into the field of exoplanets because there are other more developed and matured ways of detection and it is fascinating.
So far, besides the cool planets, I can conclude that Dr. Wright and seminars are a good combination. The passion of someone that "can give a talk to the public and realize that this is the coolest thing [he] could be doing" translates well.
In graduate school, he planned on studying black hole theory. Instead of falling into black holes, however, he "fell" into exoplanets when he decided to work with Geoff Marcy at UC Berkeley for some observing experience before going off into theory. What was meant to be a short project turned into his thesis and his career. With the accelerating pace of discovery, the field, according to Dr. Wright, offers much to individuals because "there are more interesting planets and puzzles than there are practitioners."
The HIP 14810 system claims a soft spot in Dr. Wright's heart. A system with three planets, its innermost b component is the much more massive than the outermost d component, with the intermediate c component situated in between. Upsilon Andromedae, another system he favors, has the mass scheme of its three planets in reverse, even though the periods are similar to that of the HIP 14810 planets. This was also the first system discovered to have multiple planets. For this system, he had an amusing story to tell:
Debra Fischer recounted the story of schoolchildren giving
the planets names, and the names have found some purchase (informally)
among astronomers: the middle planet, being twice the mass of Jupiter
is "Two-piter". The outer planet is "Fourpiter", and the innermost,
being small, is (obviously) "Dinky".
Even without the adorable names, exoplanets still likable, and they really fuel our team with the wonder and novelty they bring.