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A sub-Neptune transiting the young field star HD 18599 at 40 pc.

Authors :: de Leon, J P
Livingston, J H
Jenkins, J S
Vines, J I
Wittenmyer, R A
Clark, J T
Winn, J I M
Addison, B
Ballard, S
Bayliss, D
Beichman, C
Benneke, B
Berardo, D A
Bowler, B P
Brown, T
Bryant, E M
Christiansen, J
Ciardi, D
Collins, K A
Collins, K I
Source :: Monthly Notices of the Royal Astronomical Society; 6/15/2023, Vol. 522 Issue 1, p750-766, 17p
Publication Year :: 2023
Abstract: Transiting exoplanets orbiting young nearby stars are ideal laboratories for testing theories of planet formation and evolution. However, to date only a handful of stars with age <1 Gyr have been found to host transiting exoplanets. Here we present the discovery and validation of a sub-Neptune around HD 18599 , a young (300 Myr), nearby (d  = 40 pc) K star. We validate the transiting planet candidate as a bona fide planet using data from the TESS , Spitzer , and Gaia missions, ground-based photometry from IRSF , LCO , PEST , and NGTS , speckle imaging from Gemini, and spectroscopy from CHIRON , NRES , FEROS , and Minerva -Australis . The planet has an orbital period of 4.13 d , and a radius of 2.7 R <subscript>⊕</subscript> . The RV data yields a 3-σ mass upper limit of 30.5 M <subscript>⊕</subscript> which is explained by either a massive companion or the large observed jitter typical for a young star. The brightness of the host star (V ∼9 mag) makes it conducive to detailed characterization via Doppler mass measurement which will provide a rare view into the interior structure of young planets. [ABSTRACT FROM AUTHOR]