Revisiting the Transit Timing and Atmosphere Characterization of the Neptune-mass Planet HAT-P-26 b
Napaporn A-thano, Supachai Awiphan, Ing‐Guey Jiang, E. Kerins, Akshay Priyadarshi, Iain McDonald, Y. C. Joshi, Thansuda Chulikorn, Joshua J. C. Hayes, Stephen Charles, Chung-Kai Huang, Ronnakrit Rattanamala, Li‐Chin Yeh, V. S. Dhillon
Abstract
Abstract We present a transit-timing variation (TTV) and planetary atmosphere analysis of the Neptune-mass planet HAT-P-26 b. We present a new set of 13 transit light curves from optical ground-based observations and combine them with light curves from the Wide Field Camera 3 on the Hubble Space Telescope, the Transiting Exoplanet Survey Satellite, and previously published ground-based data. We refine the planetary parameters of HAT-P-26 b and undertake a TTV analysis using 33 transits obtained over seven years. The TTV analysis shows an amplitude signal of 1.98 ± 0.05 minutes, which could result from the presence of an additional ∼0.02 M Jup planet at a 1:2 mean-motion resonance orbit. Using a combination of transit depths spanning optical to near-infrared wavelengths, we find that the atmosphere of HAT-P-26 b contains <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>2.4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.9</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> % H 2 O with a derived temperature of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>590</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>50</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>60</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> K.