@article{48d139b4fd4c4946aad07a26dda4efa1,
title = "TESS-Keck Survey. IX. Masses of Three Sub-Neptunes Orbiting HD 191939 and the Discovery of a Warm Jovian plus a Distant Substellar Companion",
abstract = "Exoplanet systems with multiple transiting planets are natural laboratories for testing planetary astrophysics. One such system is HD 191939 (TOI 1339), a bright (V = 9) and Sun-like (G9V) star, which TESS found to host three transiting planets (b, c, and d). The planets have periods of 9, 29, and 38 days each with similar sizes from 3 to 3.4 R. To further characterize the system, we measured the radial velocity (RV) of HD 191939 over 415 days with Keck/HIRES and APF/Levy. We find that Mb = 10.4 ± 0.9 M and Mc = 7.2 ± 1.4 M, which are low compared to most known planets of comparable radii. The RVs yield only an upper limit on Md (<5.8 M at 2σ). The RVs further reveal a fourth planet (e) with a minimum mass of 0.34 ± 0.01 MJup and an orbital period of 101.4 ± 0.4 days. Despite its nontransiting geometry, secular interactions between planet e and the inner transiting planets indicate that planet e is coplanar with the transiting planets ({"}i < 10°). We identify a second high-mass planet (f) with 95% confidence intervals on mass between 2 and 11 MJup and period between 1700 and 7200 days, based on a joint analysis of RVs and astrometry from Gaia and Hipparcos. As a bright star hosting multiple planets with well-measured masses, HD 191939 presents many options for comparative planetary astronomy, including characterization with JWST.",
author = "Jack Lubin and {Van Zandt}, Judah and Rae Holcomb and Weiss, {Lauren M.} and Petigura, {Erik A.} and Paul Robertson and {Akana Murphy}, {Joseph M.} and Nicholas Scarsdale and Konstantin Batygin and Polanski, {Alex S.} and Batalha, {Natalie M.} and Crossfield, {Ian J.M.} and Courtney Dressing and Benjamin Fulton and Howard, {Andrew W.} and Daniel Huber and Howard Isaacson and Kane, {Stephen R.} and Arpita Roy and Corey Beard and Sarah Blunt and Ashley Chontos and Fei Dai and Dalba, {Paul A.} and Kaz Gary and Steven Giacalone and Hill, {Michelle L.} and Andrew Mayo and Teo Mocnik and Kosiarek, {Molly R.} and Malena Rice and Rubenzahl, {Ryan A.} and Latham, {David W.} and S. Seager and Winn, {Joshua N.} and Kaz Gary",
note = "Funding Information: E.A.P. acknowledges the support of the Alfred P. Sloan Foundation. L.M.W. is supported by the Beatrice Watson Parrent Fellowship and NASA ADAP grant 80NSSC19K0597. A.C. acknowledges support from the National Science Foundation through the Graduate Research Fellowship Program (DGE 1842402). D.H. acknowledges support from the Alfred P. Sloan Foundation, the National Aeronautics and Space Administration (80NSSC18K1585, 80NSSC19K0379), and the National Science Foundation (AST-1717000). I.J.M.C. acknowledges support from the NSF through grant AST-1824644. P.D. acknowledges support from a National Science Foundation Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1903811. A.B. is supported by the NSF Graduate Research Fellowship, grant No. DGE 1745301. R.A.R. is supported by the NSF Graduate Research Fellowship, grant No. DGE 1745301. C.D.D. acknowledges the support of the Hellman Family Faculty Fund, the Alfred P. Sloan Foundation, the David & Lucile Packard Foundation, and the National Aeronautics and Space Administration via the TESS Guest Investigator Program (80NSSC18K1583). J.M.A.M. is supported by the NSF Graduate Research Fellowship, grant No. DGE-1842400. J.M.A.M. also acknowledges the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining grant No. 1829740, the Brinson Foundation, and the Moore Foundation; his participation in the program has benefited this work. M.R.K is supported by the NSF Graduate Research Fellowship, grant No. DGE 1339067. Publisher Copyright: {\textcopyright} 2022. The Author(s). Published by the American Astronomical Society.",
year = "2022",
month = feb,
day = "1",
doi = "10.3847/1538-3881/ac3d38",
language = "English (US)",
volume = "163",
journal = "Astronomical Journal",
issn = "0004-6256",
publisher = "IOP Publishing Ltd.",
number = "2",
}