TOI-2005b: An Eccentric Warm Jupiter in Spin-orbit Alignment

Abstract We report the discovery and characterization of TOI-2005 b, a warm Jupiter on an eccentric ( e ∼ 0.59), 17.3 days orbit around a V mag = 9.867 rapidly rotating F-star. The object was detected as a candidate by Transiting Exoplanet Survey Satellite and the planetary nature of TOI-2005 b was then confirmed via a series of ground-based photometric, spectroscopic, and diffraction-limited imaging observations. The planet was found to reside in a low sky-projected stellar obliquity orbit ( λ = <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>4</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>8</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.3</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> degrees) via a transit spectroscopic observation using the Magellan Magellan Inamori Kyocera Echelle spectrograph. TOI-2005 b is one of a few planets known to have a low-obliquity high-eccentricity orbit, which may be the result of high-eccentricity coplanar migration. The planet has a periastron equilibrium temperature of ∼2100 K, similar to some highly irradiated hot Jupiters where atomic metal species have been detected in transmission spectroscopy, and varies by almost 1000 K during its orbit. Future observations of the atmosphere of TOI-2005b can inform us about its radiative timescales thanks to the rapid heating and cooling of the planet.