Newton, ER, Mann, AW, Tofflemire, BM, Pearce, L, Rizzuto, AC, Vanderburg, A, Martinez, RA, Wang, JJ, Ruffio, J-B, Kraus, AL, Johnson, MC, Thao, PC, Wood, ML, Rampalli, R, Nielsen, EL, Collins, KA, Dragomir, D, Hellier, C, Anderson, DR, Barclay, T, Brown, C, Feiden, G, Hart, R, Isopi, G, Kielkopf, JF, Mallia, F, Nelson, P, Rodriguez, JE, Stockdale, C, Waite, IA, Wright, DJ, Lissauer, JJ, Ricker, GR, Vanderspek, R, Latham, DW, Seager, S, Winn, JN, Jenkins, JM, Bouma, LG, Burke, CJ, Davies, M, Fausnaugh, M, Li, J, Morris, RL, Mukai, K, nor, JV, Villeneuva, S, Rosa, RJD, Macintosh, B, Mengel, MW, Okumura, J and Wittenmyer, RA (2019) TESS Hunt for Young and Maturing Exoplanets (THYME): A Planet in the 45 Myr Tucana–Horologium Association. Astrophysical Journal Letters, 880. L17 - L17. ISSN 2041-8213

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Young exoplanets are snapshots of the planetary evolution process. Planets that orbit stars in young associations are particularly important because the age of the planetary system is well constrained. We present the discovery of a transiting planet larger than Neptune but smaller than Saturn in the 45 Myr Tucana–Horologium young moving group. The host star is a visual binary, and our follow-up observations demonstrate that the planet orbits the G6V primary component, DS Tuc A (HD 222259A, TIC 410214986). We first identified transits using photometry from the Transiting Exoplanet Survey Satellite (TESS; alerted as TOI 200.01). We validated the planet and improved the stellar parameters using a suite of new and archival data, including spectra from Southern Astrophysical Research/Goodman, South African Extremely Large Telescope/High Resolution Spectrograph and Las Cumbres Observatories/Network of Robotic Echelle Spectrographs; transit photometry from Spitzer; and deep adaptive optics imaging from Gemini/Gemini Planet Imager. No additional stellar or planetary signals are seen in the data. We measured the planetary parameters by simultaneously modeling the photometry with a transit model and a Gaussian process to account for stellar variability. We determined that the planetary radius is 5.70 ± 0.17 R ⊕ and that the orbital period is 8.1 days. The inclination angles of the host star’s spin axis, the planet’s orbital axis, and the visual binary’s orbital axis are aligned within 15° to within the uncertainties of the relevant data. DS Tuc Ab is bright enough (V = 8.5) for detailed characterization using radial velocities and transmission spectroscopy.

Item Type: Article
Additional Information: This is the final published version of the article (version of record). It first appeared online via American Astronomical Society / IOP Publishing at - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: open clusters and associations, individual (Tucana-Horologium), planets and satellites, detection, individual (HD 222259A), (TIC 410214986), (TOI 200.01)
Subjects: Q Science > QB Astronomy > QB799 Stars
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Symplectic
Date Deposited: 08 Aug 2019 14:38
Last Modified: 08 Aug 2019 14:48

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