Simultaneous multicolour optical and near-IR transit photometry of GJ 1214b with SOFIA^⋆

¹ Center for Space and Habitability, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
e-mail: daniel.angerhausen@csh.unibe.ch
² Department of Extrasolar Planets and Atmospheres, Institute of Planetary Research, German Aerospace Center, Rutherfordstrasse 2, 12489 Berlin, Germany
³ Department of Sciences, Wentworth Institute of Technology, Boston, MA 02115, USA
⁴ Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA
⁵ Department of Physics and Astronomy, University of California Los Angeles (UCLA), 465 Portola Plaza, Los Angeles, CA 90095, USA
⁶ Astronomical Institute ASCR, Fričova 298, 25165 Ondrějov, Czech Republic
⁷ Deutsches SOFIA Institut, University of Stuttgart Pfaffenwaldring 29, 70569 Stuttgart, Germany
⁸ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
⁹ USRA-SOFIA Science Center, NASA Ames Research Center, Moffett Field, CA 94035, USA
¹⁰ SETI Institute, 1533 16th Place, Longmont, Colorado 80501, USA
¹¹ Centre for Astronomy and Astrophysics, TU Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
¹² University of California Observatories, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
¹³ Exoplanets and Stellar Astrophysics Laboratory, Code 667, NASA Goddard Space Flight Center Greenbelt, MD 20771, USA
¹⁴ Blue Marble Space Institute of Science, 1001 4th ave, Suite 3201 Seattle, Washington 98154, USA

Received: 2 April 2017
Accepted: 22 July 2017

Abstract

Context. The benchmark exoplanet GJ 1214b is one of the best studied transiting planets in the transition zone between rocky Earth-sized planets and gas or ice giants. This class of super-Earth or mini-Neptune planets is unknown in our solar system, yet is one of the most frequently detected classes of exoplanets. Understanding the transition from rocky to gaseous planets is a crucial step in the exploration of extrasolar planetary systems, in particular with regard to the potential habitability of this class of planets.

Aims. GJ 1214b has already been studied in detail from various platforms at many different wavelengths. Our airborne observations with the Stratospheric Observatory for Infrared Astronomy (SOFIA) add information in the Paschen-α cont. 1.9 μm infrared wavelength band, which is not accessible by any other current ground- or space-based instrument due to telluric absorption or limited spectral coverage.

Methods. We used FLIPO, the combination of the High-speed Imaging Photometer for Occultations (HIPO) and the First Light Infrared TEst CAMera (FLITECAM) and the Focal Plane Imager (FPI+) on SOFIA to comprehensively analyse the transmission signal of the possible water-world GJ 1214b through photometric observations during transit in three optical and one infrared channels.

Results. We present four simultaneous light curves and corresponding transit depths in three optical and one infrared channel, which we compare to previous observations and current synthetic atmospheric models of GJ 1214b. The final precision in transit depth is between 1.5 and 2.5 times the theoretical photon noise limit, not sensitive enough to constrain the theoretical models any better than previous observations. This is the first exoplanet observation with SOFIA that uses its full set of instruments available to exoplanet spectrophotometry. Therefore we use these results to evaluate SOFIA’s potential in this field and suggest future improvements.