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Title: DISCOVERY OF A LOW-MASS COMPANION TO A METAL-RICH F STAR WITH THE MARVELS PILOT PROJECT

Abstract

We report the discovery of a low-mass companion orbiting the metal-rich, main sequence F star TYC 2949-00557-1 during the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) pilot project. The host star has an effective temperature T{sub eff} = 6135 {+-} 40 K, logg = 4.4 {+-} 0.1, and [Fe/H] = 0.32 {+-} 0.01, indicating a mass of M = 1.25 {+-} 0.09 M{sub sun} and R = 1.15 {+-} 0.15 R{sub sun}. The companion has an orbital period of 5.69449 {+-} 0.00023 days and straddles the hydrogen burning limit with a minimum mass of 64 M{sub J} , and thus may be an example of the rare class of brown dwarfs orbiting at distances comparable to those of 'Hot Jupiters'. We present relative photometry that demonstrates that the host star is photometrically stable at the few millimagnitude level on time scales of hours to years, and rules out transits for a companion of radius {approx}>0.8 R{sub J} at the 95% confidence level. Tidal analysis of the system suggests that the star and companion are likely in a double synchronous state where both rotational and orbital synchronization have been achieved. This is the first low-mass companion detected with a multi-object,more » dispersed, fixed-delay interferometer.« less

Authors:
; ; ; ; ; ; ; ; ; ;  [1]; ; ;  [2];  [3];  [4]; ;  [5];  [6];  [7]
  1. Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 326711-2055 (United States)
  2. Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)
  3. Torun Center for Astronomy, Nicolaus Copernicus University, ul. Gagarina 11, 87-100, Torun (Poland)
  4. Indian Institute of Astrophysics, Bangalore 560034 (India)
  5. Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States)
  6. Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)
  7. Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195 (United States)
Publication Date:
OSTI Identifier:
21455073
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 718; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/718/2/1186
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; HYDROGEN BURNING; INTERFEROMETERS; JUPITER PLANET; MASS; METALS; PHOTOMETRY; RADIAL VELOCITY; STARS; SYNCHRONIZATION; ELEMENTS; MEASURING INSTRUMENTS; PLANETS; STAR BURNING; VELOCITY

Citation Formats

Fleming, Scott W., Ge Jian, Mahadevan, Suvrath, Lee, Brian, Cuong Nguyen, Duy, Morehead, Robert C., Wan Xiaoke, Zhao Bo, Liu Jian, Guo Pengcheng, Kane, Stephen R., Eastman, Jason D., Siverd, Robert J., Scott Gaudi, B., Niedzielski, Andrzej, Sivarani, Thirupathi, Stassun, Keivan G., Gary, Bruce, Wolszczan, Alex, and Barnes, Rory, E-mail: scfleming@astro.ufl.ed. DISCOVERY OF A LOW-MASS COMPANION TO A METAL-RICH F STAR WITH THE MARVELS PILOT PROJECT. United States: N. p., 2010. Web. doi:10.1088/0004-637X/718/2/1186.
Fleming, Scott W., Ge Jian, Mahadevan, Suvrath, Lee, Brian, Cuong Nguyen, Duy, Morehead, Robert C., Wan Xiaoke, Zhao Bo, Liu Jian, Guo Pengcheng, Kane, Stephen R., Eastman, Jason D., Siverd, Robert J., Scott Gaudi, B., Niedzielski, Andrzej, Sivarani, Thirupathi, Stassun, Keivan G., Gary, Bruce, Wolszczan, Alex, & Barnes, Rory, E-mail: scfleming@astro.ufl.ed. DISCOVERY OF A LOW-MASS COMPANION TO A METAL-RICH F STAR WITH THE MARVELS PILOT PROJECT. United States. doi:10.1088/0004-637X/718/2/1186.
Fleming, Scott W., Ge Jian, Mahadevan, Suvrath, Lee, Brian, Cuong Nguyen, Duy, Morehead, Robert C., Wan Xiaoke, Zhao Bo, Liu Jian, Guo Pengcheng, Kane, Stephen R., Eastman, Jason D., Siverd, Robert J., Scott Gaudi, B., Niedzielski, Andrzej, Sivarani, Thirupathi, Stassun, Keivan G., Gary, Bruce, Wolszczan, Alex, and Barnes, Rory, E-mail: scfleming@astro.ufl.ed. Sun . "DISCOVERY OF A LOW-MASS COMPANION TO A METAL-RICH F STAR WITH THE MARVELS PILOT PROJECT". United States. doi:10.1088/0004-637X/718/2/1186.
@article{osti_21455073,
title = {DISCOVERY OF A LOW-MASS COMPANION TO A METAL-RICH F STAR WITH THE MARVELS PILOT PROJECT},
author = {Fleming, Scott W. and Ge Jian and Mahadevan, Suvrath and Lee, Brian and Cuong Nguyen, Duy and Morehead, Robert C. and Wan Xiaoke and Zhao Bo and Liu Jian and Guo Pengcheng and Kane, Stephen R. and Eastman, Jason D. and Siverd, Robert J. and Scott Gaudi, B. and Niedzielski, Andrzej and Sivarani, Thirupathi and Stassun, Keivan G. and Gary, Bruce and Wolszczan, Alex and Barnes, Rory, E-mail: scfleming@astro.ufl.ed},
abstractNote = {We report the discovery of a low-mass companion orbiting the metal-rich, main sequence F star TYC 2949-00557-1 during the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) pilot project. The host star has an effective temperature T{sub eff} = 6135 {+-} 40 K, logg = 4.4 {+-} 0.1, and [Fe/H] = 0.32 {+-} 0.01, indicating a mass of M = 1.25 {+-} 0.09 M{sub sun} and R = 1.15 {+-} 0.15 R{sub sun}. The companion has an orbital period of 5.69449 {+-} 0.00023 days and straddles the hydrogen burning limit with a minimum mass of 64 M{sub J} , and thus may be an example of the rare class of brown dwarfs orbiting at distances comparable to those of 'Hot Jupiters'. We present relative photometry that demonstrates that the host star is photometrically stable at the few millimagnitude level on time scales of hours to years, and rules out transits for a companion of radius {approx}>0.8 R{sub J} at the 95% confidence level. Tidal analysis of the system suggests that the star and companion are likely in a double synchronous state where both rotational and orbital synchronization have been achieved. This is the first low-mass companion detected with a multi-object, dispersed, fixed-delay interferometer.},
doi = {10.1088/0004-637X/718/2/1186},
journal = {Astrophysical Journal},
number = 2,
volume = 718,
place = {United States},
year = {Sun Aug 01 00:00:00 EDT 2010},
month = {Sun Aug 01 00:00:00 EDT 2010}
}
  • We report the discovery via radial velocity (RV) measurements of a short-period (P = 2.430420 {+-} 0.000006 days) 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 > 2000 days. High-resolution spectroscopy of the host star yields T{sub 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{submore » 1} = 1.21 {+-} 0.08 M{sub Sun} and R{sub 1} = 1.09{sup +0.15}{sub -0.13} R{sub Sun }. 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 {sigma}, 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 {approx}0.3-0.4 M{sub Sun }. 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{sub {l_brace}2,3{r_brace}} {approx}< 1.0 M{sub Sun }, provided they are not stellar remnants. If the tertiary is not a stellar remnant, then it likely has a mass of {approx}0.5-0.6 M{sub Sun }, 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.« less
  • TYC 4110-01037-1 has a low-mass stellar companion, whose small mass ratio and short orbital period are atypical among binary systems with solar-like (T{sub eff} {approx}< 6000 K) primary stars. Our analysis of TYC 4110-01037-1 reveals it to be a moderately aged ({approx}<5 Gyr) solar-like star having a mass of 1.07 {+-} 0.08 M{sub Sun} and radius of 0.99 {+-} 0.18 R{sub Sun }. We analyze 32 radial velocity (RV) measurements from the SDSS-III MARVELS survey as well as 6 supporting RV measurements from the SARG spectrograph on the 3.6 m Telescopio Nazionale Galileo telescope obtained over a period of {approx}2more » years. The best Keplerian orbital fit parameters were found to have a period of 78.994 {+-} 0.012 days, an eccentricity of 0.1095 {+-} 0.0023, and a semi-amplitude of 4199 {+-} 11 m s{sup -1}. We determine the minimum companion mass (if sin i = 1) to be 97.7 {+-} 5.8 M{sub Jup}. The system's companion to host star mass ratio, {>=}0.087 {+-} 0.003, places it at the lowest end of observed values for short period stellar companions to solar-like (T{sub eff} {approx}< 6000 K) stars. One possible way to create such a system would be if a triple-component stellar multiple broke up into a short period, low q binary during the cluster dispersal phase of its lifetime. A candidate tertiary body has been identified in the system via single-epoch, high contrast imagery. If this object is confirmed to be comoving, we estimate it would be a dM4 star. We present these results in the context of our larger-scale effort to constrain the statistics of low-mass stellar and brown dwarf companions to FGK-type stars via the MARVELS survey.« less
  • We report the discovery of a candidate brown dwarf (BD) or a very low mass stellar companion (MARVELS-5b) to the star HIP 67526 from the Multi-object Apache point observatory Radial Velocity Exoplanet Large-area Survey (MARVELS). The radial velocity curve for this object contains 31 epochs spread over 2.5 yr. Our Keplerian fit, using a Markov Chain Monte Carlo approach, reveals that the companion has an orbital period of 90.2695{sup +0.0188}{sub -0.0187} days, an eccentricity of 0.4375 {+-} 0.0040, and a semi-amplitude of 2948.14{sup +16.65}{sub -16.55} m s{sup -1}. Using additional high-resolution spectroscopy, we find the host star has an effectivemore » temperature T{sub eff} = 6004 {+-} 34 K, a surface gravity log g (cgs) =4.55 {+-} 0.17, and a metallicity [Fe/H] =+0.04 {+-} 0.06. The stellar mass and radius determined through the empirical relationship of Torres et al. yields 1.10 {+-} 0.09 M{sub Sun} and 0.92 {+-} 0.19 R{sub Sun }. The minimum mass of MARVELS-5b is 65.0 {+-} 2.9M{sub Jup}, indicating that it is likely to be either a BD or a very low mass star, thus occupying a relatively sparsely populated region of the mass function of companions to solar-type stars. The distance to this system is 101 {+-} 10 pc from the astrometric measurements of Hipparcos. No stellar tertiary is detected in the high-contrast images taken by either FastCam lucky imaging or Keck adaptive optics imaging, ruling out any star with mass greater than 0.2 M{sub Sun} at a separation larger than 40 AU.« less
  • We describe the discovery of a likely brown dwarf (BD) companion with a minimum mass of 31.7 {+-} 2.0 M{sub Jup} to GSC 03546-01452 from the MARVELS radial velocity survey, which we designate as MARVELS-6b. For reasonable priors, our analysis gives a probability of 72% that MARVELS-6b has a mass below the hydrogen-burning limit of 0.072 M{sub Sun }, and thus it is a high-confidence BD companion. It has a moderately long orbital period of 47.8929{sup +0.0063}{sub -0.0062} days with a low eccentricity of 0.1442{sup +0.0078}{sub -0.0073}, and a semi-amplitude of 1644{sup +12}{sub -13} m s{sup -1}. Moderate resolution spectroscopymore » of the host star has determined the following parameters: T{sub eff} = 5598 {+-} 63, log g = 4.44 {+-} 0.17, and [Fe/H] = +0.40 {+-} 0.09. Based upon these measurements, GSC 03546-01452 has a probable mass and radius of M{sub *} = 1.11 {+-} 0.11 M{sub Sun} and R{sub *} = 1.06 {+-} 0.23 R{sub Sun} with an age consistent with less than {approx}6 Gyr at a distance of 219 {+-} 21 pc from the Sun. Although MARVELS-6b is not observed to transit, we cannot definitively rule out a transiting configuration based on our observations. There is a visual companion detected with Lucky Imaging at 7.''7 from the host star, but our analysis shows that it is not bound to this system. The minimum mass of MARVELS-6b exists at the minimum of the mass functions for both stars and planets, making this a rare object even compared to other BDs. It also exists in an underdense region in both period/eccentricity and metallicity/eccentricity space.« less
  • We present H I spectral-line imaging of the extremely metal-poor galaxy DDO 68. This system has a nebular oxygen abundance of only ∼3% Z {sub ☉}, making it one of the most metal-deficient galaxies known in the local volume. Surprisingly, DDO 68 is a relatively massive and luminous galaxy for its metal content, making it a significant outlier in the mass-metallicity and luminosity-metallicity relationships. The origin of such a low oxygen abundance in DDO 68 presents a challenge for models of the chemical evolution of galaxies. One possible solution to this problem is the infall of pristine neutral gas, potentially initiated during amore » gravitational interaction. Using archival H I spectral-line imaging obtained with the Karl G. Jansky Very Large Array, we have discovered a previously unknown companion of DDO 68. This low-mass (M{sub H} {sub I} = 2.8 × 10{sup 7} M {sub ☉}), recently star-forming (SFR{sub FUV} = 1.4 × 10{sup –3} M {sub ☉} yr{sup –1}, SFR{sub Hα} < 7 × 10{sup –5} M {sub ☉} yr{sup –1}) companion has the same systemic velocity as DDO 68 (V {sub sys} = 506 km s{sup –1}; D = 12.74 ± 0.27 Mpc) and is located at a projected distance of ∼42 kpc. New H I maps obtained with the 100 m Robert C. Byrd Green Bank Telescope provide evidence that DDO 68 and this companion are gravitationally interacting at the present time. Low surface brightness H I gas forms a bridge between these objects.« less