TESS Hunt for Young and Maturing Exoplanets (THYME). V. A Sub-Neptune Transiting a Young Star in a Newly Discovered 250Myr Association

Tofflemire, Benjamin M. and Rizzuto, Aaron C. and Newton, Elisabeth R. and Kraus, Adam L. and Mann, Andrew W. and Vanderburg, Andrew and Nelson, Tyler and Hawkins, Keith and Wood, Mackenna L. and Zhou, George ORCID: https://orcid.org/0000-0002-4891-3517 and Quinn, Samuel N. and Howell, Steve B. and Collins, Karen A. and Schwarz, Richard P. and Stassun, Keivan G. and Bouma, Luke G. and Essack, Zahra and Osborn, Hugh and Boyd, Patricia T. and Furesz, Gabor and Glidden, Ana and Twicken, Joseph D. and Wohler, Bill and McLean, Brian and Ricker, George R. and Vanderspek, Roland and Latham, David W. and Seager, S. and Winn, Joshua N. and Jenkins, Jon M. (2021) TESS Hunt for Young and Maturing Exoplanets (THYME). V. A Sub-Neptune Transiting a Young Star in a Newly Discovered 250Myr Association. The Astronomical Journal, 161 (4):171. pp. 1-32. ISSN 0004-6256


Abstract

The detection and characterization of young planetary systems offer a direct path to study the processes that shape planet evolution. We report on the discovery of a sub-Neptune-sized planet orbiting the young star HD 110082 (TOI-1098). Transit events we initially detected during TESS Cycle 1 are validated with time-series photometry from Spitzer. High-contrast imaging and high-resolution, optical spectra are also obtained to characterize the stellar host and confirm the planetary nature of the transits. The host star is a late-F dwarf (Må = 1.2Me) with a low-mass, M dwarf binary companion (Må = 0.26Me) separated by nearly one arcminute (∼6200 au). Based on its rapid rotation and Lithium absorption, HD 110082 is young, but is not a member of any known group of young stars (despite proximity to the Octans association). To measure the age of the system, we search for coeval, phase-space neighbors and compile a sample of candidate siblings to compare with the empirical sequences of young clusters and to apply quantitative age-dating techniques. In doing so, we find that HD 110082 resides in a new young stellar association we designate MELANGE-1, with an age of 250-+7050 Myr. Jointly modeling the TESS and Spitzer light curves, we measure a planetary orbital period of 10.1827 days and radius of Rp = 3.2 ± 0.1R+. HD 110082 b’s radius falls in the largest 12% of field-age systems with similar host-star mass and orbital period. This finding supports previous studies indicating that young planets have larger radii than their field-age counterparts.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 07 Mar 2022 04:17
Last Modified: 30 Mar 2022 03:54
Uncontrolled Keywords: Exoplanet astronomy; Exoplanets; Mini Neptunes; Stellar astronomy; Wide binary stars; Moving clusters; Stellar ages; Transits; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Funding Details:
Identification Number or DOI: https://doi.org/10.3847/1538-3881/abdf53
URI: http://eprints.usq.edu.au/id/eprint/45033

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