Optical and Infrared Phase Curves of the Lava Planet K2-141 b
- 1Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany (zieba@mpia.de)
- 2Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
- 3Department of Physics, McGill University, 3600 rue University, Montréal, QC H3A 2T8, Canada
- 4McGill Space Institute; Institute for Research on Exoplanets; Centre for Research in Astrophysics of Quebec
- 5Department of Earth & Planetary Sciences, McGill University, 3450 rue University, Montréal, QC H3A 0E8, Canada
- 6Centre for Research in Earth and Space Sciences, York University, 4700 Keele st., Toronto, Ontario, M3J 1P3, Canada
- 7Department of Physics (Atmospheric, Oceanic and Planetary Physics), University of Oxford, Parks Rd, Oxford, OX1 3PU, UK
- 8BAER Institute, NASA Ames Research Center, Naval Air Station, Moffett Field, CA 94035, USA
- 9Department of the Geophysical Sciences, University of Chicago, USA
- 10Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Padua, Italy
K2-141 b is a transiting, small (1.5 RE) Ultra-Short-Period (USP) planet orbiting its star every 6.7 hours discovered by the Kepler space telescope. The planet’s high surface temperature of more than 2000 K makes it an excellent target for atmospheric studies by the observation of its thermal emission. We present 65 hours of continuous photometric observations of K2-141 b collected with Spitzer’s IRAC Channel 2 at 4.5 microns spanning 10 full phases of the orbit. Our best fit model of the Spitzer data shows no significant offset of the thermal hotspot and is inconsistent with the observed offset of the well-studied USP planet 55 Cnc e at a 3.7 sigma level. We measure an eclipse depth of 142 +/- 40 ppm and an amplitude variation of 120 +/- 40 ppm in the infrared. The joint analysis of the observations collected in the two photometric bands favors a non-zero geometric albedo with Ag = 0.26 +/- 0.07 and a tentative temperature gradient. With a dayside temperature of 2141 -361 +352 K and a night-side temperature of 1077 -623 +473 K we also find no evidence of heat redistribution on the planet. We compare the observations to a 1D rock vapor model and a 1D circulation toy model and argue that the data are best explained by a thin rock vapor atmosphere with a thermal inversion.
How to cite: Zieba, S., Zilinskas, M., Kreidberg, L., Cowan, N., Nguyen, G., Miguel, Y., Pierrehumbert, R., Lupu, R., Dang, L., Hammond, M., Malavolta, L., and Carone, L.: Optical and Infrared Phase Curves of the Lava Planet K2-141 b, European Planetary Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-476, https://doi.org/10.5194/epsc2021-476, 2021.
