MULTI-COLOR TRANSIT PHOTOMETRY OF GJ 1214b THROUGH BJHK{sub s} BANDS AND A LONG-TERM MONITORING OF THE STELLAR VARIABILITY OF GJ 1214

• Published in: The Astrophysical journal 2013-08, Vol.773 (2)
• Main Authors: Narita, Norio, Hori, Yasunori, Onitsuka, Masahiro, Sukom, Amnart, Tamura, Motohide, Suenaga, Takuya, Takahashi, Yasuhiro H., Fukui, Akihiko, Kuroda, Daisuke, Yanagisawa, Kenshi, Ikoma, Masahiro, Kurosaki, Kenji, Kawashima, Yui, Nagayama, Takahiro, Nakajima, Yasushi, Hirano, Teruyuki, Kawauchi, Kiyoe, Kuzuhara, Masayuki, Ohnuki, Hiroshi, Izumiura, Hideyuki
• Format: Article
• Language: English
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BRIGHTNESS; CAMERAS; COLOR; HYDROGEN; INFRARED SURVEYS; MARKOV PROCESS; MOLECULAR WEIGHT; MONTE CARLO METHOD; PHOTOMETRY; PLANETS; STARS; TELESCOPES; VISIBLE RADIATION
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/773/2/144

We present five new transit light curves of GJ 1214b taken in the BJHK{sub s} bands. Two transits were observed in the B band using the Subaru Prime Focus Camera (Suprime-Cam) and the Faint Object Camera and Spectrograph (FOCAS) instruments on board the Subaru 8.2 m telescope, and one transit was done in the JHK{sub s} bands simultaneously with the Simultaneous Infrared Imager for Unbiased Survey (SIRIUS) camera on the Infrared Survey Facility (IRSF) 1.4 m telescope. Markov Chain Monte Carlo analyses show that the planet-to-star radius ratios are R{sub p}/R{sub s} = 0.11651 {+-} 0.00065 (B band, Subaru/Suprime-Cam), R{sub p}/R{sub s} = 0.11601 {+-} 0.00117 (B band, Subaru/FOCAS), R{sub p}/R{sub s} = 0.11654 {+-} 0.00080 (J band, IRSF/SIRIUS), R{sub p}/R{sub s}= 0.11550{sup +0.00142}{sub -0.00153} (H band, IRSF/SIRIUS), and R{sub p}/R{sub s} = 0.11547 {+-} 0.00127 (K{sub s} band, IRSF/SIRIUS). The Subaru Suprime-Cam transit photometry shows a possible spot-crossing feature. Comparisons of the new transit depths and those from previous studies with the theoretical models by Howe and Burrows suggest that the high molecular weight atmosphere (e.g., 1% H{sub 2}O + 99% N{sub 2}) models are most likely, however, the low molecular weight (hydrogen-dominated) atmospheres with extensive clouds are still not excluded. We also report a long-term monitoring of the stellar brightness variability of GJ 1214 observed with the MITSuME 50 cm telescope in the g', R{sub c}, and I{sub c} bands simultaneously. The monitoring was conducted for 32 nights spanning 78 nights in 2012, and we find a periodic brightness variation with a period of P{sub s} = 44.3 {+-} 1.2 days and semi-amplitudes of 2.1% {+-} 0.4% in the g' band, 0.56% {+-} 0.08% in the R{sub c} band, and 0.32% {+-} 0.04% in the I{sub c} band.