Very low mass stellar and substellar companions to solar-like stars from marvels. II. A short-period companion orbiting an f star with evidence of a stellar tertiary and significant mutual inclination

Scott W. Fleming, Jian Ge, Rory Barnes, Thomas G. Beatty, Justin R. Crepp, Nathan De Lee, Massimiliano Esposito, Bruno Femenia, Leticia Ferreira, Bruce Gary, B. Scott Gaudi, Luan Ghezzi, Jonay I. González Hernández, Leslie Hebb, Peng Jiang, Brian Lee, Ben Nelson, Gustavo F. Porto De Mello, Benjamin J. Shappee, Keivan StassunTodd A. Thompson, Benjamin M. Tofflemire, John P. Wisniewski, W. Michael Wood-Vasey, Eric Agol, Carlos Allende Prieto, Dmitry Bizyaev, Howard Brewington, Phillip A. Cargile, Louis Coban, Korena S. Costello, Luis N. Da Costa, Melanie L. Good, Nelson Hua, Stephen R. Kane, Gary R. Lander, Jian Liu, Bo Ma, Suvrath Mahadevan, Marcio A.G. Maia, Elena Malanushenko, Viktor Malanushenko, Demitri Muna, Duy Cuong Nguyen, Daniel Oravetz, Martin Paegert, Kaike Pan, Joshua Pepper, Rafael Rebolo, Eric J. Roebuck, Basilio X. Santiago, Donald P. Schneider, Alaina Shelden, Audrey Simmons, Thirupathi Sivarani, Stephanie Snedden, Chelsea L.M. Vincent, Xiaoke Wan, Ji Wang, Benjamin A. Weaver, Gwendolyn M. Weaver, Bo Zhao

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Abstract

We report the discovery via radial velocity (RV) measurements of a short-period (P = 2.430420 ± 0.000006days) companion to the F-type main-sequence star TYC 2930-00872-1. A long-term trend in the RV data also suggests the presence of a tertiary stellar companion with P > 2000days. High-resolution spectroscopy of the host star yields T eff = 6427 ± 33 K, log g = 4.52 ± 0.14, and [Fe/H] = -0.04 ± 0.05. These parameters, combined with the broadband spectral energy distribution (SED) and a parallax, allow us to infer a mass and radius of the host star of M 1 = 1.21 ± 0.08 M and R 1 = 1.09+0.15 - 0.13 R. The minimum mass of the inner companion is below the hydrogen-burning limit; however, the true mass is likely to be substantially higher. We are able to exclude transits of the inner companion with high confidence. Further, the host star spectrum exhibits a clear signature of Ca H and K core emission, indicating stellar activity, but a lack of photometric variability and small vsin I suggest that the primary's spin axis is oriented in a pole-on configuration. The rotational period of the primary estimated through an activity-rotation relation matches the orbital period of the inner companion to within 1.5 σ, suggesting that the primary and inner companion are tidally locked. If the inner companion's orbital angular momentum vector is aligned with the stellar spin axis as expected through tidal evolution, then it has a stellar mass of 0.3-0.4 M. Direct imaging limits the existence of stellar companions to projected separations <30 AU. No set of spectral lines and no significant flux contribution to the SED from either companion are detected, which places individual upper mass limits of M {2, 3} ≲ 1.0 M, provided they are not stellar remnants. If the tertiary is not a stellar remnant, then it likely has a mass of 0.5-0.6 M, and its orbit is likely significantly inclined from that of the secondary, suggesting that the Kozai-Lidov mechanism may have driven the dynamical evolution of this system.

Original languageEnglish (US)
Article number72
JournalAstronomical Journal
Volume144
Issue number3
DOIs
StatePublished - Sep 1 2012

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Fleming, S. W., Ge, J., Barnes, R., Beatty, T. G., Crepp, J. R., De Lee, N., Esposito, M., Femenia, B., Ferreira, L., Gary, B., Gaudi, B. S., Ghezzi, L., González Hernández, J. I., Hebb, L., Jiang, P., Lee, B., Nelson, B., Porto De Mello, G. F., Shappee, B. J., ... Zhao, B. (2012). Very low mass stellar and substellar companions to solar-like stars from marvels. II. A short-period companion orbiting an f star with evidence of a stellar tertiary and significant mutual inclination. Astronomical Journal, 144(3), [72]. https://doi.org/10.1088/0004-6256/144/3/72