The LHS 1678 System: Two Earth-sized Transiting Planets and an Astrometric Companion Orbiting an M Dwarf Near the Convective Boundary at 20 pc
Article
Article Title | The LHS 1678 System: Two Earth-sized Transiting Planets and an Astrometric Companion Orbiting an M Dwarf Near the Convective Boundary at 20 pc |
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ERA Journal ID | 1048 |
Article Category | Article |
Authors | Silverstein, Michele L. (Author), Schlieder, Joshua E. (Author), Barclay, Thomas (Author), Hord, Benjamin J. (Author), Jao, Wei-Chun (Author), Vrijmoet, Eliot Halley (Author), Henry, Todd J. (Author), Cloutier, Ryan (Author), Kostov, Veselin B. (Author), Kruse, Ethan (Author), Winters, Jennifer G. (Author), Irwin, Jonathan M. (Author), Kane, Stephen R. (Author), Stassun, Keivan G. (Author), Huang, Chelsea (Author), Kunimoto, Michelle (Author), Tey, Evan (Author), Vanderburg, Andrew (Author), Astudillo-Defru, Nicola (Author), Bonfils, Xavier (Author), Brasseur, C. E. (Author), Charbonneau, David (Author), Ciardi, David R. (Author), Collins, Karen A. (Author), Collins, Kevin I. (Author), Conti, Dennis M. (Author), Crossfield, Ian J. M. (Author), Daylan, Tansu (Author), Doty, John P. (Author), Dressing, Courtney D. (Author), Gilbert, Emily A. (Author), Horne, Keith (Author), Jenkins, Jon M. (Author), Latham, David W. (Author), Mann, Andrew W. (Author), Matthews, Elisabeth (Author), Paredes, Leonardo A. (Author), Quinn, Samuel N. (Author), Ricker, George R. (Author), Schwarz, Richard P. (Author), Seager, Sara (Author), Sefako, Ramotholo (Author), Shporer, Avi (Author), Smith, Jeffrey C. (Author), Stockdale, Christopher (Author), Tan, Thiam-Guan (Author), Torres, Guillermo (Author), Twicken, Joseph D. (Author), Vanderspek, Roland (Author), Wang, Gavin (Author) and Winn, Joshua N. (Author) |
Journal Title | The Astronomical Journal |
Journal Citation | 163 (4), pp. 1-31 |
Article Number | 151 |
Number of Pages | 31 |
Year | 2022 |
Publisher | IOP Publishing |
Place of Publication | United States |
ISSN | 0004-6256 |
1538-3881 | |
Digital Object Identifier (DOI) | https://doi.org/10.3847/1538-3881/ac32e3 |
Web Address (URL) | https://iopscience.iop.org/article/10.3847/1538-3881/ac32e3/meta |
Abstract | We present the Transiting Exoplanet Survey Satellite (TESS) discovery of the LHS 1678 (TOI-696) exoplanet system, comprised of two approximately Earth-sized transiting planets and a likely astrometric brown dwarf orbiting a bright (V J = 12.5, K s = 8.3) M2 dwarf at 19.9 pc. The two TESS-detected planets are of radius 0.70 ± 0.04 R ⊕ and 0.98 ± 0.06 R ⊕ in 0.86 day and 3.69 day orbits, respectively. Both planets are validated and characterized via ground-based follow-up observations. High Accuracy Radial Velocity Planet Searcher RV monitoring yields 97.7 percentile mass upper limits of 0.35 M ⊕ and 1.4 M ⊕ for planets b and c, respectively. The astrometric companion detected by the Cerro Tololo Inter-American Observatory/Small and Moderate Aperture Telescope System 0.9 m has an orbital period on the order of decades and is undetected by other means. Additional ground-based observations constrain the companion to being a high-mass brown dwarf or smaller. Each planet is of unique interest; the inner planet has an ultra-short period, and the outer planet is in the Venus zone. Both are promising targets for atmospheric characterization with the James Webb Space Telescope and mass measurements via extreme-precision radial velocity. A third planet candidate of radius 0.9 ± 0.1 R ⊕ in a 4.97 day orbit is also identified in multicycle TESS data for validation in future work. The host star is associated with an observed gap in the lower main sequence of the Hertzsprung-Russell diagram. This gap is tied to the transition from partially to fully convective interiors in M dwarfs, and the effect of the associated stellar astrophysics on exoplanet evolution is currently unknown. The culmination of these system properties makes LHS 1678 a unique, compelling playground for comparative exoplanet science and understanding the formation and evolution of small, short-period exoplanets orbiting low-mass stars. |
Keywords | Exoplanet systems (484); Transit photometry (1709); Low mass stars (2050); M dwarf stars (982); Astrometric binary stars (79); Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Institution of Origin | University of Southern Queensland |
Byline Affiliations | National Aeronautics and Space Administration (NASA), United States |
NASA Goddard Space Flight Center, United States | |
United States Army Corps of Engineers Regional Economic Systems Institute, United States | |
Center for Astrophysics Harvard and Smithsonian, United States | |
Center for Astrophysics Harvard and Smithsonian, United States ** | |
Harvard-Smithsonian Centre for Astrophysics, United States | |
University of California, United States | |
Vanderbilt University, United States | |
Centre for Astrophysics | |
Massachusetts Institute of Technology, United States | |
Catholic University of the Most Holy Conception (UCSC), Chile | |
Grenoble Alpes University, France | |
University of St Andrews, United Kingdom | |
California Institute of Technology (Caltech), United States | |
George Mason University, United States | |
American Association of Variable Star Observers, United States | |
University of Kansas, United States | |
Noqsi Aerospace, United States | |
NASA Ames Research Center, United States | |
University of North Carolina, United States | |
University of Geneva, Switzerland | |
Patashnick Voorheesville Observatory, United States | |
South African Astronomical Observatory, South Africa | |
SETI Institute, United States | |
Hazelwood Observatory, Australia | |
Perth Exoplanet Survey Telescope Observatory, Australia | |
Tsinghua International School, China | |
Princeton University, United States |
https://research.usq.edu.au/item/q7233/the-lhs-1678-system-two-earth-sized-transiting-planets-and-an-astrometric-companion-orbiting-an-m-dwarf-near-the-convective-boundary-at-20-pc
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