KELT-1b: A Strongly Irradiated, Highly Inflated, Short Period, 27 Jupiter-mass Companion Transiting a Mid-F Star

December 2012 • 2012ApJ...761..123S

Authors • Siverd, Robert J. • Beatty, Thomas G. • Pepper, Joshua • Eastman, Jason D. • Collins, Karen • Bieryla, Allyson • Latham, David W. • Buchhave, Lars A. • Jensen, Eric L. N. • Crepp, Justin R. • Street, Rachel • Stassun, Keivan G. • Gaudi, B. Scott • Berlind, Perry • Calkins, Michael L. • DePoy, D. L. • Esquerdo, Gilbert A. • Fulton, Benjamin J. • Fűrész, Gábor • Geary, John C. • Gould, Andrew • Hebb, Leslie • Kielkopf, John F. • Marshall, Jennifer L. • Pogge, Richard • Stanek, K. Z. • Stefanik, Robert P. • Szentgyorgyi, Andrew H. • Trueblood, Mark • Trueblood, Patricia • Stutz, Amelia M. • van Saders, Jennifer L.

Abstract • We present the discovery of KELT-1b, the first transiting low-mass companion from the wide-field Kilodegree Extremely Little Telescope-North (KELT-North) transit survey. A joint analysis of the spectroscopic, radial velocity, and photometric data indicates that the V = 10.7 primary is a mildly evolved mid-F star with T _eff = 6516 ± 49 K, log g = 4.228^+0.014 _-0.021, and [Fe/H] = 0.052 ± 0.079, with an inferred mass M _* = 1.335 ± 0.063 M _⊙ and radius R _* = 1.471^+0.045 _-0.035 R _⊙. The companion is a low-mass brown dwarf or a super-massive planet with mass M_P = 27.38 ± 0.93 M _Jup and radius R_P = 1.116^+0.038 _-0.029 R _Jup. The companion is on a very short (~29 hr) period circular orbit, with an ephemeris T_c (BJD_TDB) = 2455909.29280 ± 0.00023 and P = 1.217501 ± 0.000018 days. KELT-1b receives a large amount of stellar insolation, resulting in an estimated equilibrium temperature assuming zero albedo and perfect redistribution of T _eq = 2423⁺³⁴ _-27 K. Comparison with standard evolutionary models suggests that the radius of KELT-1b is likely to be significantly inflated. Adaptive optics imaging reveals a candidate stellar companion to KELT-1 with a separation of 588 ± 1 mas, which is consistent with an M dwarf if it is at the same distance as the primary. Rossiter-McLaughlin measurements during transit imply a projected spin-orbit alignment angle λ = 2 ± 16 deg, consistent with a zero obliquity for KELT-1. Finally, the vsin I _* = 56 ± 2 km s^-1 of the primary is consistent at ~2σ with tidal synchronization. Given the extreme parameters of the KELT-1 system, we expect it to provide an important testbed for theories of the emplacement and evolution of short-period companions, as well as theories of tidal dissipation and irradiated brown dwarf atmospheres.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2012ApJ...761..123S
• PDF https://iopscience.iop.org/article/10.1088/0004-637X/761/2/123/pdf
• PDF https://stacks.iop.org/0004-637X/761/123/pdf
• PREPRINT http://arxiv.org/abs/1206.1635
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/761/123
• DATA http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?type=REFERENCE&bibcode=2012ApJ...761..123S
• DATA https://irsa.ipac.caltech.edu/bibdata/2012/S/2012ApJ...761..123S.html
• ELECTR https://doi.org/10.1088%2F0004-637X%2F761%2F2%2F123
• SPIRES http://inspirehep.net/search?p=find+eprint+arXiv:1206.1635