The GJ436 system: directly determined astrophysical parameters of an M dwarf and implications for the transiting hot Neptune

von Braun, Kaspar and Boyajian, Tabetha S. and Kane, Stephen R. and Hebb, Leslie and van Belle, Gerard T. and Farrington, Chris and Ciardi, David R. and Knutson, Heather A. and ten Brummelaar, Theo A. and Lopez-Morales, Mercedes and McAlister, Harold A. and Schaefer, Gail and Ridgway, Stephen and Cameron, Andrew Collier and Goldfinger, P. J. and Turner, Nils H. and Sturmann, Laszlo and Sturmann, Judit (2012) The GJ436 system: directly determined astrophysical parameters of an M dwarf and implications for the transiting hot Neptune. The Astrophysical Journal, 753 (2). pp. 171-179. ISSN 0004-637X

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Abstract

The late-type dwarf GJ436 is known to host a transiting Neptune-mass planet in a 2.6day orbit. We present results of our interferometric measurements to directly determine the stellar diameter (R ⊙ = 0.455 ± 0.018 R ⊙) and effective temperature (T EFF = 3416 ± 54 K). We combine our stellar parameters with literature time-series data, which allows us to calculate physical and orbital system parameters, including GJ436's stellar mass (M ⊙ = 0.507+0.071 - 0.062 M ⊙), stellar density (ρ * = 5.37+0.30 - 0.27 ρ ⊙), planetary radius (Rp = 0.369+0.015 - 0.015 R Jupiter), and planetary mass (Mp = 0.078+0.007 - 0.008 M Jupiter), implying a mean planetary density of ρp = 1.55+0.12 - 0.10 ρJupiter. These values are generally in good agreement with previous literature estimates based on assumed stellar mass and photometric light curve fitting. Finally, we examine the expected phase curves of the hot Neptune GJ436b, based on various assumptions concerning the efficiency of energy redistribution in the planetary atmosphere, and find that it could be constrained with Spitzer monitoring observations.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Access to published version in accordance with the copyright policy of the publisher.
Faculty / Department / School: No Faculty
Date Deposited: 07 Jun 2017 21:37
Last Modified: 27 Jun 2017 04:46
Uncontrolled Keywords: infrared stars; planetary systems;fundamental parameters (radii, temperatures, luminosities); individual stars (GJ 436); late-type stars; interferometric techniques;
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1088/0004-637X/753/2/171
URI: http://eprints.usq.edu.au/id/eprint/32143

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