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

June 2023 • 2023MNRAS.522..750D

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. • Crossfield, I. • Deming, D. • Dragomir, D. • Dressing, C. D. • Fukui, A. • Gan, T. • Giacalone, S. • Gill, S. • Gorjian, V. • González Alvarez, E. • Hesse, K. • Horner, J. • Howell, S. B. • Jenkins, J. M. • Kane, S. R. • Kendall, A. • Kielkopf, J. F. • Kreidberg, L. • Latham, D. W. • Liu, H. • Lund, M. B. • Matson, R. • Matthews, E. • Mengel, M. W. • Morales, F. • Mori, M. • Narita, N. • Nishiumi, T. • Okumura, J. • Plavchan, P. • Quinn, S. • Rabus, M. • Ricker, G. • Rudat, A. • Schlieder, J. • Schwarz, R. P. • Seager, S. • Shporer, A. • Smith, A. M. S. • Stassun, K. • Tamura, M. • Tan, T. G. • Tinney, C. • Vanderspek, R. • Werner, M. W. • West, R. G. • Wright, D. • Zhang, H. • Zhou, G.

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_⊕ . The RV data yields a 3-σ mass upper limit of 30.5 M_⊕ 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.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2023MNRAS.522..750D
• PDF https://academic.oup.com/mnras/pdf-lookup/doi/10.1093/mnras/stad894
• PREPRINT http://arxiv.org/abs/2210.08179
• DATA https://archive.gemini.edu/searchform/publication=2023MNRAS.522..750D
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2023MNRAS.522..750D
• DATA https://irsa.ipac.caltech.edu/bibdata/2023/D/2023MNRAS.522..750D.html
• ELECTR https://doi.org/10.1093%2Fmnras%2Fstad894