2MASS 0213+3648 C: A wide T3 benchmark companion to an an active, old M dwarf binary

Deacon, N. R.; Magnier, E. A.; Liu, Mengmeng; Schlieder, Joshua E.; Aller, Kimberly M.; Best, William M. J.; Bowler, Brendan P.; Burgett, W. S.; Chambers, K.; Draper, P. W.; Flewelling, H.; Hodapp, Klaus W.; Kaiser, N.; Metcalfe, N.; Sweeney, William E.; Wainscoat, R. J.; Waters, C.

doi:10.1093/mnras/stx065

Cited by 20 publications

(6 citation statements)

References 87 publications

(168 reference statements)

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“…f Confirmed binary as reported in Burgasser et al (2003cBurgasser et al ( , 2006bBurgasser et al ( , 2010; Kirkpatrick et al (2010); Dupuy & Liu (2012); and this paper References-Source discovery/classification: (1) Artigau et al (2006), (2) Best et al (2013), (3) Burgasser et al (1999), (4) Burgasser et al (2000a), (5) Burgasser et al (2002), (6) Burgasser et al (2003a), (7) Burgasser et al (2003b), (8) Burgasser et al (2004), ( 9) Burgasser et al (2010), (10) Chiu et al (2006), (11) Deacon et al (2011), (12) Deacon et al (2017), (13) Dupuy & Liu (2012), ( 14) Faherty et al (2009), ( 15) Hawley et al (2002), ( 16) Kirkpatrick et al (2010), ( 17)…”

Section: Introductionsupporting

confidence: 60%

The Brown Dwarf Kinematics Project (BDKP). V. Radial and Rotational Velocities of T Dwarfs from Keck/NIRSPEC High-Resolution Spectroscopy

Hsu,

Burgasser,

Theissen

et al. 2021

Preprint

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We report multi-epoch radial velocities, rotational velocities, and atmospheric parameters for 37 T-type brown dwarfs observed with Keck/NIRSPEC. Using a Markov Chain Monte Carlo forwardmodeling method, we achieve median precisions of 0.5 km s −1 and 0.9 km s −1 for radial and rotational velocities, respectively. All of the T dwarfs in our sample are thin disk brown dwarfs. We confirm previously reported moving group associations for four T dwarfs. However, the lack of spectral indicators of youth in two of these sources suggests that these are chance alignments. We confirm two previously un-resolved binary candidates, the T0+T4.5 2MASS J11061197+2754225 and the L7+T3.5 2MASS J21265916+7617440, with orbital periods of 4 yr and 12 yr, respectively. We find a kinematic age of 3.5±0.3 Gyr for local T dwarfs, consistent with nearby late-M dwarfs (4.1±0.3 Gyr). Removal of thick disk L dwarfs in the local ultracool dwarf sample gives a similar age for L dwarfs (4.2±0.3 Gyr), largely resolving the local L dwarf age anomaly. The kinematic ages of local late-M, L, and T dwarfs can be accurately reproduced with population simulations incorporating standard assumptions of the mass function, star formation rate, and brown dwarf evolutionary models. A kinematic dispersion break is found at the L4-L6 subtypes, likely reflecting the terminus of the stellar Main Sequence. We provide a compilation of precise radial velocities for 172 late-M, L, and T dwarfs within ∼20 pc of the Sun.

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Section: Introductionsupporting

confidence: 60%

The Brown Dwarf Kinematics Project (BDKP). V. Radial and Rotational Velocities of T Dwarfs from Keck/NIRSPEC High-Resolution Spectroscopy

Hsu,

Burgasser,

Theissen

et al. 2021

Preprint

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“…At the distance of our clusters this equates to a tangential motion of ∼1 mas/yr, significantly larger than the proper motion measurement errors. We perform a conservative cut on our data by adapting the astrometric difference defined by Deacon et al (2017). This is the quadrature sum of the number of standard deviations that each pair of measurements for the proposed binary differ by.…”

Section: Identifying Comoving Pairsmentioning

confidence: 99%

Wide binaries are rare in open clusters

Deacon

Kraus

2020

Monthly Notices of the Royal Astronomical Society

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The population statistics of binary stars are an important output of star formation models. However, populations of wide binaries evolve over time due to interactions within a system’s birth environment and the unfolding of wide, hierarchical triple systems. Hence, the wide binary populations observed in star-forming regions or OB associations may not accurately reflect the wide binary populations that will eventually reach the field. We use Gaia DR2 data to select members of three open clusters, Alpha Per, the Pleiades, and Praesepe and to flag cluster members that are likely unresolved binaries due to overluminosity or elevated astrometric noise. We then identify the resolved wide binary population in each cluster, separating it from coincident pairings of unrelated cluster members. We find that these clusters have an average wide binary fraction in the 300–3000 au projected separation range of 2.1$\pm ^{0.4}_{0.2}$ per cent increasing to 3.0$\pm ^{0.8}_{0.7}$ per cent for primaries with masses in the 0.5–1.5 M⊙ range. This is significantly below the observed field wide binary fraction, but shows some wide binaries survive in these dynamically highly processed environments. We compare our results with another open cluster (the Hyades) and two populations of young stars that likely originated in looser associations (young moving groups and the Pisces-Eridanus stream). We find that the Hyades also has a deficit of wide binaries while the products of looser associations have wide binary fractions at or above field level.

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“…Metallicity estimates are viable using model atmosphere analyses. While there has been previous such studies for one to a few objects (e.g., Saumon et al 2007;Bowler et al 2010b;Leggett et al 2017), many analyses have used models with only the solar metallicity (e.g., Cushing et al 2008;Stephens et al 2009;Del Burgo et al 2009;Liu et al 2011a;Schneider et al 2015;Deacon et al 2017).…”

Section: Metallicity Distributionmentioning

confidence: 99%

Uniform Forward-Modeling Analysis of Ultracool Dwarfs. II. Atmospheric Properties of 55 Late-T Dwarfs

Zhang,

Liu,

Marley

et al. 2021

Preprint

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We present a large uniform forward-modeling analysis for 55 late-T (T7−T9) dwarfs, using low-resolution (R ≈ 50−250) nearinfrared (1.0 − 2.5 µm) spectra and cloudless Sonora-Bobcat model atmospheres. We derive the objects' effective temperatures, surface gravities, metallicities, radii, masses, and bolometric luminosities using our newly developed Bayesian framework, and use the resulting population properties to test the model atmospheres. We find (1) our objects' fitted metallicities are 0.3 − 0.4 dex lower than those of nearby stars; (2) their ages derived from spectroscopic parameters are implausibly young (10 Myr−0.4 Gyr);(3) their fitted effective temperatures show a similar spread as empirical temperature scales at a given spectral type but are ∼ 50 − 200 K hotter for T8 dwarfs; and (4) their spectroscopically inferred masses are unphysically small (mostly 1 − 8 M Jup ). These suggest the Sonora-Bobcat assumptions of cloudless and chemical-equilibrium atmospheres do not adequately reproduce late-T dwarf spectra. We also find a gravity-and a metallicity-dependence of effective temperatures as a function of spectral type. Combining the resulting parameter posteriors of our sample, we quantify the degeneracy between fitted surface gravity and metallicity such that an increase in Z combined with a 3.4× increase in log g results in a spectrum that has similar fitted parameters. We note the systematic difference between late-T dwarf spectra and Sonora-Bobcat models is on average ≈ 2% − 4% of the objects' peak J-band fluxes over the 1.0 − 2.5 µm range, implying modeling systematics will exceed measurement uncertainties when analyzing data with J-band S/N 50. Using our large, high-quality sample, we examine the spectral-fitting residuals as a function of wavelength and atmospheric properties to discern how to improve the model assumptions. Our work constitutes the largest analysis of brown dwarf spectra using multi-metallicity models and the most systematic examination of ultracool model atmospheres to date.

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2MASS 0213+3648 C: A wide T3 benchmark companion to an an active, old M dwarf binary

Cited by 20 publications

References 87 publications

The Brown Dwarf Kinematics Project (BDKP). V. Radial and Rotational Velocities of T Dwarfs from Keck/NIRSPEC High-Resolution Spectroscopy

The Brown Dwarf Kinematics Project (BDKP). V. Radial and Rotational Velocities of T Dwarfs from Keck/NIRSPEC High-Resolution Spectroscopy

Wide binaries are rare in open clusters

Uniform Forward-Modeling Analysis of Ultracool Dwarfs. II. Atmospheric Properties of 55 Late-T Dwarfs

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