High-Precision Dynamical Masses of Very Low Mass Binaries

Konopacky, Quinn; Ghez, A. M.; Barman, Travis; Rice, Emily L.; Bailey, John I.; White, R. J.; McLean, Ian S.; Duchêne, Gaspard

doi:10.1088/0004-637x/711/2/1087

Cited by 159 publications

(353 citation statements)

References 72 publications

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“…Likewise, HD3651B and HD114762B orbit solar-type stars but their projected separations are 480 AU and 128 AU, respectively (Liu et al 2007;Bowler et al 2009). Many other dynamical measurements have targeted companions to M-stars, thus helping to circumvent issues with contrast (Zapatero Osorio et al 2004;Ireland et al 2008;Dupuy et al 2009b;Konopacky et al 2010), but M-star metallicities are notoriously difficult to determine (Johnson & Apps 2009). Low-mass companions to solar-type stars have also been studied using Doppler measurements in combination with Hubble Space Telescope astrometry (Benedict et al 2010) and Hipparcos intermediate astrometry (Sahlmann et al 2011), but indirect observations preclude a comparison between spectral models and dynamical mass measurements by definition.…”

Section: Summary and Discussionmentioning

confidence: 99%

The Dynamical Mass and Three-Dimensional Orbit of Hr7672b: A Benchmark Brown Dwarf With High Eccentricity

Crepp

Johnson

Fischer

et al. 2012

ApJ

103

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The companion to the G0V star HR7672 directly imaged by Liu et al. has moved measurably along its orbit since the discovery epoch, making it possible to determine its dynamical properties. Originally targeted with adaptive optics because it showed a long-term radial velocity (RV) acceleration (trend), we have monitored this star with precise Doppler measurements and have now established a 24 year time baseline. The RV variations show significant curvature (change in the acceleration) including an inflection point. We have also obtained a recent image of HR7672B with NIRC2 at Keck. The astrometry also shows curvature. In this paper, we use jointly fitted Doppler and astrometric models to calculate the three-dimensional orbit and dynamical mass of the companion. The mass of the host star is determined using a direct radius measurement from CHARA interferometry in combination with high-resolution spectroscopic modeling. We find that HR7672B has a highly eccentric, e = 0.50 +0.01 −0.01 , near edge-on, i = 97.3 +0.4 −0.5 deg, orbit with semimajor axis, a = 18.3 +0.4 −0.5 AU. The mass of the companion is m = 68.7 +2.4 −3.1 M J . HR7672B thus resides near the substellar boundary, just below the hydrogen-fusing limit. These measurements of the companion mass are independent of its brightness and spectrum and establish HR7672B as a rare and precious "benchmark" brown dwarf with a well-determined mass, age, and metallicity essential for testing theoretical evolutionary models and synthetic spectral models. Indeed, we find that such models under-predict its luminosity by a factor of ≈2. HR 7672B is presently the only L, T, or Y dwarf known to produce an RV trend around a solar-type star.

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Section: Summary and Discussionmentioning

confidence: 99%

The Dynamical Mass and Three-Dimensional Orbit of Hr7672b: A Benchmark Brown Dwarf With High Eccentricity

Crepp

Johnson

Fischer

et al. 2012

ApJ

103

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“…Detailed studies of orbital elements of individual low mass binaries, and dynamical masses, are needed for empirical calibration of models for low-mass stars, and significant effort has therefore been made in recent years to better characterise in particular ultracool dwarfs (e.g. Bouy et al 2008;Bonnefoy et al 2009;Konopacky et al 2010;Dupuy et al 2010;Schlieder et al 2014;Zhou et al 2014). In addition, the recent discoveries and dedicated surveys for M dwarf planets require accurate stellar physical properties in order to derive reliable planetary parameters, furthering the interest for characterising M dwarfs (e.g., Johnson et al 2012;Mann et al 2012Mann, Gaidos & Ansdell 2013;Muirhead et al 2012Muirhead et al , 2014Dressing & Charbonneau 2013;Newton et al 2014Newton et al , 2015Gaidos et al 2014;Alonso-Floriano et al 2015;Bowler et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Characterization of close visual binaries from the AstraLux Large M Dwarf Survey

Bergfors¹,

Brandner²,

Bonnefoy³

et al. 2015

Mon. Not. R. Astron. Soc.

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We present VLT/SINFONI J, H + K spectra of seven close visual pairs in M dwarf binary/triple systems, discovered or observed by the AstraLux M dwarf survey. We determine the spectral types to within ±1.0 subclasses from comparison to template spectra and the strength of K-band water absorption, and derive effective temperatures. The results are compared to optical spectral types of the unresolved binary/multiple systems, and we confirm that our photometric method to derive spectral types in the AstraLux M dwarf survey is accurate. We look for signs of youth such as chromospheric activity and low surface gravity, and find an age in the range 0.25 − 1 Gyr for the GJ 852 system. Strong Li absorption is detected in optical spectra of the triple system J024902 obtained with FEROS at the ESO-MPG 2.2 m telescope. The equivalent width of the absorption suggests an age consistent with the β Pic moving group. However, further observations are needed to establish group membership. Ongoing orbital monitoring will provide dynamical masses and thus calibration of evolutionary models for low mass stars.

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“…Burgasser et al (2007, and references therein). Following these discoveries, the introduction of laser guide star (LGS) adaptive optics (AO) systems on ground-based telescopes provided the means of assessing the dynamical mass of such systems (Bouy et al 2004;Dupuy et al 2010;Konopacky et al 2010). More recently, Konopacky et al (2012) obtained resolved LGS AO spectroscopic measurements of individual component rotation velocities for a sample of eleven very low mass (VLM) dwarf binaries (M tot ≤ 0.185 M , as defined by Close et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Spin-orbit alignment in the very low mass binary regime

Harding

Hallinan

Konopacky

et al. 2013

A&A

Self Cite

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Studies of solar-type binaries have found coplanarity between the equatorial and orbital planes of systems with <40 AU separation. By comparison, the alignment of the equatorial and orbital axes in the substellar regime, and the associated implications for formation theory, are relatively poorly constrained. Here we present the discovery of the rotation period of 3.32 ± 0.15 h from 2MASS J0746+20A -the primary component of a tight (2.7 AU) ultracool dwarf binary system (L0+L1.5). The newly discovered period, together with the established period via radio observations of the other component, and the well constrained orbital parameters and rotational velocity measurements, allow us to infer alignment of the equatorial planes of both components with the orbital plane of the system to within 10 degrees. This result suggests that solar-type binary formation mechanisms may extend down into the brown dwarf mass range, and we consider a number of formation theories that may be applicable in this case. This is the first such observational result in the very low mass binary regime. In addition, the detected period of 3.32 ± 0.15 h implies that the reported radio period of 2.07 ± 0.002 h is associated with the secondary star, not the primary, as was previously claimed. This in turn refutes the claimed radius of 0.78 ± 0.1 R J for 2MASS J0746+20A, which we demonstrate to be 0.99 ± 0.03 R J .

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High-Precision Dynamical Masses of Very Low Mass Binaries

Cited by 159 publications

References 72 publications

The Dynamical Mass and Three-Dimensional Orbit of Hr7672b: A Benchmark Brown Dwarf With High Eccentricity

The Dynamical Mass and Three-Dimensional Orbit of Hr7672b: A Benchmark Brown Dwarf With High Eccentricity

Characterization of close visual binaries from the AstraLux Large M Dwarf Survey

Spin-orbit alignment in the very low mass binary regime

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