NASA Astrobiology Institute (NAI)

1. Extrasolar Planets

   Project Investigators: Drake Deming

   Summary

   D. Deming and summer Intern K. Todorov (Connecticut College) measured the emergent infrared spectrum of the giant transiting exoplanet HAT-P-1, using data from the Spitzer Space Telescope. A future extension of this technique to observations of SuperEarths transiting lower main sequence stars may enable the identification of biomarkers in the emergent spectra of life-bearing terrestrial planets

   Astrobiology Roadmap Objectives:

   • Objective 1.2: Indirect and direct astronomical observations of extrasolar habitable planets

   Project Progress

   Dr. Drake Deming and summer intern Kamen Todorov (Connecticut College) worked on analysis of new Spitzer exoplanet data, in collaboration with Dr. Joseph Harrington of the University of Central Florida. The data comprise observations of the secondary eclipse of the giant transiting planet HAT-P-1. This planet orbits very close to its star, and it cannot be separated from the star by imaging. Instead, Deming and Todorov exploited the fact that the planet passes in front of the star during primary eclipse (also called a transit) and passes behind the star during secondary eclipse.

   Spitzer data can be analyzed to detect the small decrement in the total flux of the system during secondary eclipse and thereby isolate the infrared light from the planet. Repeating this at four Spitzer wavelengths (3.6, 4.5, 5.6 and 8.0 micrometers) allows them to re-construct a crude spectrum of this extrasolar giant planet. Their preliminary results indicate that the planet has an inverted atmospheric temperature profile (temperature rising with height), due to the strong external irradiation by its parent star. Although this “hot Jupiter” exoplanet is not likely to support life, the same technique could be applied to data from the forthcoming James Webb Space Telescope (2013 launch), to search for biomarkers on “SuperEarth” planets that are beginning to be discovered in orbit about lower main sequence stars.

   
   

   Figure 1:Eclipse of the giant transiting exoplanet HAT-P-1 as observed by the Spitzer Space Telescope, and analyzed by GCA summer intern Kamen Todorov (Connecticut College).

Publications

Deming, D.  (2008).  Emergent Exoplanet Flux: Review of the Spitzer Results.  I.A.U. Symposium, 253.  Boston, MA.