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New Planet Discovery Using Transit Methods

Over 135 planets have now been discovered by studying their effects on the star they orbit, which produce a pronounced wobble. But so far, only a few have been found by using the transit method, detecting the periodic dimming of a star as a planet passes between it and the Earth. Now a planet called TrES-1 has been located by the Trans-Atlantic Exoplanet Survey (TrES), which uses small, inexpensive telescopes to find planets around bright stars. You can read about the TrES discovery through this press release from the University Corporation for Atmospheric Research.

Obviously, finding planets through the transit method means locating those stars whose orbital plane is lined up properly for the Earth-bound observer to see the crossing (and you have to be careful to eliminate eclipsing binaries). But rare as these may be, the beauty of discovering such planets is that we can now make some direct observations of planetary atmospheres, and we’ll get a good reading on the mass and size of any planets so observed. The team discovering TrES-1 included scientists from the Astrophysical Institute of the Canaries, the National Center for Atmospheric Research, the Harvard-Smithsonian Center for Astrophysics, Lowell Observatory, and the California Institute of Technology. The team was led by NCAR’s Timothy Brown, who built the optical system for the project at Tenerife in the Canaries. The actual discovery was the work of graduate student Roi Alonso Sobrino. Nice work!

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  • ljk June 3, 2007, 0:11

    A Ground-Based Search for Thermal Emission from the Exoplanet TrES-1

    Authors: Heather A. Knutson, David Charbonneau, Drake Deming, L. Jeremy Richardson

    (Submitted on 29 May 2007)

    Abstract: Eclipsing planetary systems give us an important window on extrasolar planet atmospheres. By measuring the depth of the secondary eclipse, when the planet moves behind the star, we can estimate the strength of the thermal emission from the day side of the planet. Attaining a ground-based detection of one of these eclipses has proven to be a significant challenge, as time-dependent variations in instrument throughput and atmospheric seeing and absorption overwhelm the small signal of the eclipse at infrared wavelengths. We gathered a series of simultaneous L grism spectra of the transiting planet system TrES-1 and a nearby comparison star of comparable brightness, allowing us to correct for these effects in principle. Combining the data from two eclipses, we demonstrate a detection sensitivity of 0.15% in the eclipse depth relative to the stellar flux. This approaches the sensitivity required to detect the planetary emission, which theoretical models predict should lie between 0.05-0.1% of the stellar flux in our 2.9-4.3 micron bandpass. We explore the factors that ultimately limit the precision of this technique, and discuss potential avenues for future improvements.

    Comments: 10 pages, 1 table, four figures, accepted for publication in PASP

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:0705.4288v1 [astro-ph]

    Submission history

    From: Heather Knutson [view email]

    [v1] Tue, 29 May 2007 20:08:40 GMT (60kb)