Hubble Space Telescope astrometry of the closest brown dwarf binary system – I. Overview and improved orbit★

Bedin, L. R.; Pourbaix, Dimitri; Apai, Dániel; Burgasser, Adam J.; Buenzli, E.; Boffin, H. M. J.; Libralato, Mattia

doi:10.1093/mnras/stx1177

Cited by 20 publications

(37 citation statements)

References 72 publications

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“…Our measurements of Luhman 16 AB's mass ratio and barycentric motion parameters are consistent with previous estimates in the literature utilizing recent astrometry only. The GeMS-derived measurements of the Luhman 16 AB separation in 2014-2015 agree closely with Hubble Space Telescope (HST) measurements made during the same epoch (Bedin et al 2017), and the derived mutual orbit agrees with those measurements to within the HST uncertainties of 0.3 − 0.4 milliarcseconds.…”

supporting

confidence: 73%

“…Our measurements of the total mass M tot = M A + M B , semi-major axis a, eccentricity e, longitude of ascending node Ω, argument of periastron ω, time of periastron passage τ , inclination i, and period P are more precise by factors of 2−30. Although our measurements of the longitude of ascending node Ω and argument of periastron ω are different from those of Bedin et al (2017) by a π phase shift and the inclination i has an additional negative sign, our measurements of all orbital parameters are consistent to within the 1σ error bars quoted in Bedin et al (2017), with the exception of the eccentricity e. Our measurement of this parameter has a 68.3% confidence interval of [0.33, 0.37] and the value from Bedin et al (2017) has confidence limits of [0.399, 0.527], so the difference is 1.76σ discrepant from our most likely value of 0.35. Given that this is the only parameter with a discrepancy above 1σ, and the probability of such a difference occurring by chance alone is not small, we conclude that all of our orbital parameters are consistent to within the errors.…”

Section: Bedincontrasting

confidence: 58%

“…By jointly fitting for the mutual orbit and barycentric motion parameters, we account for any correlated uncertainty between these. We present comparisons between our measurements and those of Bedin et al (2017) in the conclusion.…”

Section: Introductionmentioning

confidence: 75%

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Individual, Model-independent Masses of the Closest Known Brown Dwarf Binary to the Sun

Garcia

Ammons

Salama

et al. 2017

ApJ

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At a distance of ∼ 2 pc, our nearest brown dwarf neighbor, Luhman 16 AB, has been extensively studied since its discovery 3 years ago, yet its most fundamental parameter -the masses of the individual dwarfs -has not been constrained with precision. In this work we present the full astrometric orbit and barycentric motion of Luhman 16 AB and the first precision measurements of the individual component masses. We draw upon archival observations spanning 31 years from the European Southern Observatory (ESO) Schmidt Telescope, the Deep Near-Infrared Survey of the Southern Sky (DENIS), public FORS2 data on the Very Large Telescope (VLT), and new astrometry from the Gemini South Multiconjugate Adaptive Optics System (GeMS). Finally, we include three radial velocity measurements of the two components from VLT/CRIRES, spanning one year. With this new data sampling a full period of the orbit, we use a Markov Chain Monte Carlo algorithm to fit a 16-parameter model incorporating mutual orbit and barycentric motion parameters and constrain the individual masses to be 27.9

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supporting

confidence: 73%

Section: Bedincontrasting

confidence: 58%

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Individual, Model-independent Masses of the Closest Known Brown Dwarf Binary to the Sun

Garcia

Ammons

Salama

et al. 2017

ApJ

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“…The binary brown dwarf system Luhman 16 (WISE J1049; Luhman 2013) is composed of two objects with spectral types L7.5 and T0.5, respectively (Burgasser et al 2013;Kniazev et al 2013). With a distance of only 1.996 pc (Bedin et al 2017), Luhman 16 is the third closest system to the Sun (after α Cen and Barnard's star) and its two components are the nearest known brown dwarfs. The system has an orbital period of 27.5 ± 0.4 years and a semimajor axis of 3.56 ± 0.03 AU, with dynamically determined masses of 33.5 ± 0.3 Jupiter masses for Luhman 16A and 28.6 ± 0.3 for Luhman 16B (Lazorenko & Sahlmann 2018).…”

Section: The Luhman 16 Systemmentioning

confidence: 99%

Weather on Other Worlds. VI. Optical Spectrophotometry of Luhman 16B Reveals Large-amplitude Variations in the Alkali Lines

Heinze,

Metchev,

Kurtev

et al. 2021

Preprint

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Using a novel wide-slit, multi-object approach with the GMOS spectrograph on the 8-meter Gemini South telescope, we have obtained precise time-series spectrophotometry of the binary brown dwarf Luhman 16 at optical wavelengths over two full nights. The B component of this binary system is known to be variable in the red optical and near-infrared with a period of 5 hr and an amplitude of 5-20%. Our observations probe its spectrally-resolved variability in the 6000-10000 Å range. At wavelengths affected by the extremely strong, broadened spectral lines of the neutral alkali metals (the potassium doublet centered near 7682 Å and the sodium doublet at 5893 Å), we see photometric variations that differ strikingly from the those of the 8000-10000 Å 'red continuum' that dominates our detected flux. On UT 2014 February 24, these variations are anticorrelated with the red continuum, while on Feb 25 they have a large relative phase shift. The extent to which the wavelength-dependent photometric behavior diverges from that of the red continuum appears to correlate with the strength of the alkali absorption. We consider but ultimately reject models in which our observations are explained by lightning or auroral activity. A more likely cause is cloud-correlated, altitude-dependent variations in the gas-phase abundances of sodium and potassium, which are in chemical equilibrium with their chlorides in brown dwarf atmospheres. Clouds could influence these chemical equilibria by changing the atmospheric temperature profile and/or through cloud particles acting as chemical catalysts.

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“…This study focuses on the L/T spectral transition brown dwarf binary WISEJ104915.57-531906.1 or, in the following, Luhman 16. Even though the closest known brown dwarf system to the Sun (d= 1.9955 ± 0.0004 pc, Bedin et al 2017), Luhman 16 was discovered only in 2013 (Luhman 2013). The binary consists of a 34.2 +1.3 −1.1 M Jup L-type primary and a 27.9 +1.0 −1.1 M Jup T-type secondary brown dwarf component (Ammons & Garcia 2019).…”

Section: Introductionmentioning

confidence: 99%

TESS Observations of the Luhman 16AB Brown Dwarf System: Rotational Periods, Lightcurve Evolution, and Zonal Circulation

Apai,

Nardiello,

Bedin

2021

Preprint

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Brown dwarfs were recently found to display rotational modulations, commonly attributed to cloud cover of varying thickness, possibly modulated by planetary-scale waves. However, the long-term, continuous, high-precision monitoring data to test this hypothesis for more objects is lacking. By applying our novel photometric approach to TESS data, we extract a high-precision lightcurve of the closest brown dwarfs, which form the binary system Luhman 16AB. Our observations, that cover about 100 rotations of Luhman 16B, display continuous lightcurve evolution. The periodogram analysis shows that the rotational period of the component that dominates the lightcurve is 5.28 h. We also find evidence for periods of 2.5 h, 6.94 h, and 90.8 h. We show that the 2.5 h and 5.28 h periods emerge from Luhman 16B and that they consist of multiple, slightly shifted peaks, revealing the presence of high-speed jets and zonal circulation in this object. We find that the lightcurve evolution is well fit by the planetary-scale waves model, further supporting this interpretation. We argue that the 6.94 h peak is likely the rotation period of Luhman 16A. By comparing the rotational periods to observed v sin(i) measurements, we show that the two brown dwarfs are viewed at angles close to their equatorial planes. We also describe a long-period (P∼91 h) evolution in the lightcurve, which we propose emerges from the vortex-dominated polar regions. Our study paves the way toward direct comparisons of the predictions of global circulation models to observations via periodogram analysis.

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Hubble Space Telescope astrometry of the closest brown dwarf binary system – I. Overview and improved orbit★

Cited by 20 publications

References 72 publications

Individual, Model-independent Masses of the Closest Known Brown Dwarf Binary to the Sun

Individual, Model-independent Masses of the Closest Known Brown Dwarf Binary to the Sun

Weather on Other Worlds. VI. Optical Spectrophotometry of Luhman 16B Reveals Large-amplitude Variations in the Alkali Lines

TESS Observations of the Luhman 16AB Brown Dwarf System: Rotational Periods, Lightcurve Evolution, and Zonal Circulation

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