Research
My research focuses on comets. Records of comet observations go back to ancient times. However, for most of human history they have been given an ill nature, cast as bad omens. It was not until the 18th century that it was realized that comets were objects that orbited the Sun, just like the planets. Until 1986, when the Halley Armada of spacecraft performed its flybys of Comet 1P/Halley, that we knew the nature of the nucleus, the small, icy heart of the comet which is responsible for the coma and the majestic tails which have been so well chronicled in human history. In the past century we have learned much about these beautiful and mysterious objects, but we have only scratched the tip of the proverbial iceberg.
One of the primary motivations for studying and understanding comets is that they consist of pristine matter that has been unalterred since the formation of the solar system. Their composition reflects the conditions in the nebula from which everything else in the solar system formed. So if we are to understand how are solar system formed, thr study of comets will be crucial in reaching that goal.
Currently I am reducing echelle spectra taken with the 3.5 meter telescope at APO of Comet 17P/Holmes in late October 2007. Normally a insignificant comet which barely becomes bright enough to see in small telescopes, 17P underwent a tremendous outburst in brightness, becoming 1 million times more luminous over the span of a few hours and easily appearing as a naked eye object. Outbursts in comets are normal, but 17P's outburst is the largest on record. Even more bizarre is that this is the second time 17P has undergone an outburst of this magnitude; it was in a similar state when it was discovered in 1892. The level of activity was similar to Comet C/1995 O1 Hale-Bopp in 1997, one of the most active comets on record. So the question is how a small, usually dim comet comes to rival the activity of Hale-Bopp, even if it for a short period of time. The spectra we have cover the week after the outburst. Of particular interest is the detection of atomic oxygen, hydrogen, sodium, C2, C3, and CN. Results of this analysis will be presented at DPS in October 2009.
In March 2007 I observed a Pluto occultation with Dr. Steven Souza at the
Magdelena Ridge Observatory, as part of an MIT-Williams collaborative project
on occultation studies of small bodies in the outer solar system. That summer
I reduced occultation data from the June 2006 occultation to search for signs
of rings or moons. The search produced a negative result, but we were able to
place upper bounds on the opacity and size of any debris that may be present.
The paper is currently being written. My undergraduate thesis was on the
related topic of occultations by cometary comae, and involved making
predictions of potential occultations and then observing them with the 24-inch
telescope at Hopkins Observatory, located on the Williams College campus. I
was able to observe several candidate events, but none produced an
occultation. I hope that future astronomy students at Williams will continue
to pursue this project, as there is much more that can be done.
Publications
Waves in Pluto's Upper Atmosphere
Person, Elliot, Gulbis, Zuluaga, Babcock, McKay, Pasachoff, Souza, Hubbard,
Kulesa, McCarthy, Kern, Levine, Bosh, Ryan, Ryan, Meyer, & Wolf 2008,
AJ 136, 1510-1518
Stellar Occultation by Pluto of P445.3 (2UCAC 25823784) on 2007 March 18 (UT)
Person, Elliot, Gulbis, Zuluaga, Babcock, McKay, Pasachoff, Souza, Hubbard,
Kulesa, McCarthy, Kern, Levine, Bosh, Ryan, Ryan, Meyer, & Wolf 2007,
IAU Circular 8825 as (31340) Pluto
Meetings
October 2007: Division of Planetary Sciences meeting,
Observational Results from the 2007 March 18 Pluto Stellar
Occultation
Pasachoff, Babcock, Souza, McKay, Person, Elliot, Gulbis, Zuluaga, Hill, Ryan
& Ryan
October 2007: Division of Planetary Sciences meeting,
High Altitude Structure in Pluto's Atmosphere from the 2007
March 18 Stellar Occultation
Person, Elliot, Gulbis, Zuluaga, Babcock, Pasachoff, McKay, Souza, Hubbard,
Kulesa, McCarthy, Kern, Levine, Bosh, Ryan, Ryan, Meyer, Wolf & Hill
October 2007: Division of Planetary Sciences meeting,
Electron-Multiplying CCD Imaging: Effectiveness for Stellar
Occultations by Faint Objects
Gulbis, Elliot, Person, Souza, Babcock, Pasachoff, McKay & Zuluaga
