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TOPIC: MARVELS-1b

Blobrana

L

Posts: 131433

Date: May 3 20:02 2013

MARVELS-1	Permalink

Title: MARVELS-1: A face-on double-lined binary star masquerading as a resonant planetary system; and consideration of rare false positives in radial velocity planet searches Authors: Jason T. Wright, Arpita Roy, Suvrath Mahadevan, Sharon X. Wang, Eric B. Ford, Matt Payne, Brian L. Lee, Ji Wang, Justin R. Crepp, B. Scott Gaudi, Jason Eastman, Joshua Pepper, Jian Ge, Scott W. Fleming, Luan Ghezzi, Jonay I. Gonzalez-Hernandez, Phillip Cargile, Keivan G. Stassun, John Wisniewski, Leticia Dutra-Ferreira, Gustavo F. Porto de Mello, Marcio A. G. Maia, Luiz Nicolaci da Costa, Ricardo L. C. Ogando, Basilio X. Santiago, Donald P. Schneider, Fred R. Hearty We have analysed new and previously published radial velocity observations of MARVELS-1, known to have an ostensibly substellar companion in a ~6- day orbit. We find significant (~100 m/s) residuals to the best-fit model for the companion, and these residuals are naively consistent with an interior giant planet with a P = 1.965d in a nearly perfect 3:1 period commensuribility (\|Pb/Pc - 3\| < 10^{-4}). We have performed several tests for the reality of such a companion, including a dynamical analysis, a search for photometric variability, and a hunt for contaminating stellar spectra. We find many reasons to be critical of a planetary interpretation, including the fact that most of the three-body dynamical solutions are unstable. We find no evidence for transits, and no evidence of stellar photometric variability. We have discovered two apparent companions to MARVELS-1 with adaptive optics imaging at Keck; both are M dwarfs, one is likely bound, and the other is likely a foreground object. We explore false-alarm scenarios inspired by various curiosities in the data. Ultimately, a line profile and bisector analysis lead us to conclude that the ~100 m/s residuals are an artifact of spectral contamination from a stellar companion contributing ~15-30% of the optical light in the system. We conclude that origin of this contamination is the previously detected radial velocity companion to MARVELS-1, which is not, as previously reported, a brown dwarf, but in fact a G dwarf in a face-on orbit. Read more (1820kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Nov 24 09:58 2010

MARVELS-1b	Permalink

Title: MARVELS-1b: A Short-Period, Brown Dwarf Desert Candidate from the SDSS-III MARVELS Planet Search Authors: Brian L. Lee, Jian Ge, Scott W. Fleming, Keivan G. Stassun, B. Scott Gaudi, Rory Barnes, Suvrath Mahadevan, Jason D. Eastman, Jason Wright, Robert J. Siverd, Bruce Gary, Luan Ghezzi, Chris Laws, John P. Wisniewski, G. F. Porto de Mello, Ricardo L. C. Ogando, Marcio A. G. Maia, Luiz Nicolaci da Costa, Thirupathi Sivarani, Joshua Pepper, Duy Cuong Nguyen, Leslie Hebb, Nathan De Lee, Ji Wang, Xiaoke Wan, Bo Zhao, Liang Chang, John Groot, Frank Varosi, Fred Hearty, Kevin Hanna, J. C. van Eyken, Stephen R. Kane, Eric Agol, Dmitry Bizyaev, John J. Bochanski, Howard Brewington, Zhiping Chen, Erin Costello, Liming Dou, Daniel J. Eisenstein, Adam Fletcher, Eric B. Ford, Pengcheng Guo, Jon A. Holtzman, Peng Jiang, R. French Leger, Jian Liu, Daniel C. Long, Elena Malanushenko, Viktor Malanushenko, Mohit Malik, Daniel Oravetz, Kaike Pan, Pais Rohan, Donald P. Schneider, Alaina Shelden, Stephanie A. Snedden, Audrey Simmons, B. A. Weaver, David H. Weinberg, Ji-Wei Xie et al. (10 additional authors not shown) We present a new short-period brown dwarf candidate around the star TYC 1240-00945-1. This candidate was discovered in the first year of the Multi-object APO Radial Velocity Exoplanets Large-area Survey (MARVELS), which is part of the third phase of the Sloan Digital Sky Survey (SDSS-III), and we designate the brown dwarf as MARVELS-1b. MARVELS uses the technique of dispersed fixed-delay interferometery to simultaneously obtain radial velocity measurements for 60 objects per field using a single, custom-built instrument that is fibre fed from the SDSS 2.5-m telescope. From our 20 radial velocity measurements spread over a ~370 d time baseline, we derive a Keplerian orbital fit with semi-amplitude K=2.533±0.025 km/s, period P=5.8953±0.0004 d, and eccentricity consistent with circular. Independent follow-up radial velocity data confirm the orbit. Adopting a mass of 1.37±0.11 M_Sun for the slightly evolved F9 host star, we infer that the companion has a minimum mass of 28.0±1.5 M_Jup, a semimajor axis 0.071±0.002 AU assuming an edge-on orbit, and is probably tidally synchronized. We find no evidence for coherent instrinsic variability of the host star at the period of the companion at levels greater than a few millimagnitudes. The companion has an a priori transit probability of ~14%. Although we find no evidence for transits, we cannot definitively rule them out for companion radii ~<1 R_Jup. Read more (1047kb, PDF) __________________

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