HD 191939: Three Sub-Neptunes Transiting a Sun-like Star Only 54 pc Away

Badenas-Agusti, Mariona and Gunther, Maximilian N. and Daylan, Tansu and Mikal-Evans, Thomas and Vanderburg, Andrew and Huang, Chelsea X. ORCID: https://orcid.org/0000-0003-0918-7484 and Matthews, Elisabeth and Rackham, Benjamin V. and Bieryla, Allyson and Stassun, Keivan G. and Kane, Stephen R. and Shporer, Avi and Fulton, Benjamin J. and Hill, Michelle L. and Nowak, Grzegorz and Ribas, Ignasi and Palle, Enric and Jenkins, Jon M. and Latham, David W. and Seager, Sara and Ricker, George R. and Vanderspek, Roland K. and Winn, Joshua N. and Abril-Pla, Oriol and Collins, Karen A. and Serra, Pere Guerra and Niraula, Prajwal and Rustamkulov, Zafar and Barclay, Thomas and Crossfield, Ian J. M. and Howell, Steve B. and Ciardi, David R. and Gonzales, Erica J. and Schlieder, Joshua E. and Caldwell, Douglas A. and Fausnaugh, Michael and McDermott, Scott and Paegert, Martin and Pepper, Joshua and Rose, Mark E. and Twicken, Joseph D. (2020) HD 191939: Three Sub-Neptunes Transiting a Sun-like Star Only 54 pc Away. The Astronomical Journal, 160 (3):113. pp. 1-18. ISSN 0004-6256

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We present the discovery of three sub-Neptune-sized planets transiting the nearby and bright Sun-like star HD 191939 (TIC 269701147, TOI 1339), a K s = 7.18 mag G8 V dwarf at a distance of only 54 pc. We validate the planetary nature of the transit signals by combining 5 months of data from the Transiting Exoplanet Survey Satellite with follow-up ground-based photometry, archival optical images, radial velocities, and high angular resolution observations. The three sub-Neptunes have similar radii (Rb=3.42-0.11+0.11, Rc=3.23-0.11+0.11, and Rd=3.16-0.11+0.11,R⊕), and their orbits are consistent with a stable, circular, and coplanar architecture near mean-motion resonances of 1:3 and 3:4 (P b = 8.88, P c = 28.58, and P d = 38.35 days). The HD 191939 system is an excellent candidate for precise mass determinations of the planets with high-resolution spectroscopy due to the host star's brightness and low chromospheric activity. Moreover, the system's compact and near-resonant nature can provide an independent way to measure planetary masses via transit timing variations while also enabling dynamical and evolutionary studies. Finally, as a promising target for multiwavelength transmission spectroscopy of all three planets' atmospheres, HD 191939 can offer valuable insight into multiple sub-Neptunes born from a protoplanetary disk that may have resembled that of the early Sun.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version deposited in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 04 Apr 2022 01:11
Last Modified: 24 May 2022 05:20
Uncontrolled Keywords: Exoplanet systems (484); Exoplanets (498); Transit photometry (1709); Exoplanet detection methods (489); Astronomical techniques (1684); Astrophysics - Earth and Planetary Astrophysics
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Identification Number or DOI: https://doi.org/10.3847/1538-3881/aba0b5
URI: http://eprints.usq.edu.au/id/eprint/47438

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