K2-260 b: a hot Jupiter transiting an F star, and K2-261 b: a warm Saturn around a bright G star

Abstract

We present the discovery and confirmation of two new transiting giant planets from the Kepler extended mission K2. K2-260 b is a hot Jupiter transiting a V = 12.7 F6V star in K2 Field 13, with a mass and radius of M = 1.39 +0.05 −0.06 M and R = 1.69 ± 0.03 R . The planet has an orbital period of P = 2.627 days, and a mass and radius of M P = 1.42 +0.31 −0.32 M J and R P = 1.552 +0.048 −0.057 R J . This is the first K2 hot Jupiter with a detected secondary eclipse in the Kepler bandpass, with a depth of 71 ± 15 ppm, which we use to estimate a geometric albedo of A g ∼ 0.2. We also detected a candidate stellar companion at 0.6" from K2-260; we find that it is very likely physically associated with the system, in which case it would be an M5-6V star at a projected separation of ∼ 400 AU. K2-261 b is a warm Saturn transiting a bright (V = 10.5) G7IV/V star in K2 Field 14. The host star is a metal-rich ([Fe/H]= 0.36 ± 0.06), mildly evolved 1.10 +0.01 −0.02 M star with R = 1.65 ± 0.04 R . Thanks to its location near the main sequence turn-off, we can measure a relatively precise age of 8.8 +0.4 −0.3 Gyr. The planet has P = 11.633 days, M P = 0.223 ± 0.031 M J , and R P = 0.850 +0.026 −0.022 R J , and its orbit is eccentric (e = 0.39 ± 0.15). Its brightness and relatively large transit depth make this one of the best known warm Saturns for follow-up observations to further characterize the planetary system.

Public HARPS radial velocity database corrected for systematic errors

“…This collection of stars, are representative of a volume-limited, long-lasting HARPS surveys dedicated to solar-mass G-dwarf stars (Pepe et al 2004;Lo Curto et al 2010;Moutou et al 2011;Lo Curto et al 2013;Udry et al 2019), low-mass M-dwarfs Trifon Trifonov et al: A public HARPS radial velocity database corrected for systematic errors (Bonfils et al 2005;Mayor et al 2009;Forveille et al 2009;Bonfils et al 2013;Anglada-Escudé et al 2016;Astudillo-Defru et al 2017;Ribas et al 2018) and metal-poor stars (Santos et al 2011;Faria et al 2016;Mortier et al 2016), which all target nearby stars. The remaining ∼ 28% of the HARPS sample (with distance > 120 pc) are typically bright main sequence stars of spectral types A0 to F6, some fainter and more distant transiting planet hosts observed by more recent RV follow-up campaigns of transit planet candidates from the HATSouth (Bakos et al 2013;Brahm et al 2016;Henning et al 2018;Espinoza et al 2019), WASP-south (Pollacco et al 2006;Gillon et al 2009;Nielsen et al 2019), and the K2 extended mission (Howell et al 2014;Grziwa et al 2016;Johnson et al 2018), or evolved subgiant and giant branch stars of spectral types G8 IV − K4 III. Figure 3 shows some basic observational statistics from the employed HARPS sample.…”

TESS Hunt for Young and Maturing Exoplanets (THYME). IV. Three Small Planets Orbiting a 120 Myr Old Star in the Pisces–Eridanus Stream*

“…We modeled the transit with misttborn Johnson et al 2018). This routine uses batman (Kreidberg 2015) to produce the transit model of Mandel & Agol (2002) and explores the posterior with the Markov Chain Monte Carlo sampler emcee (Foreman-Mackey et al 2013).…”

TESS Hunt for Young and Maturing Exoplanets (THYME): A Planet in the 45 Myr Tucana–Horologium Association

“…We simultaneously fit the TESS and Spitzer photometry using the transit fitting code misttborn. 9 misttborn was first used in Mann et al (2016a) and has been used for a number of more recent works including Johnson et al (2018). Briefly, we fit each system using emcee, and produced photometric transit models using batman (Kreidberg 2015), which is based on the transit model of Mandel & Agol (2002).…”