A T8.5 Brown Dwarf Member of the Ξ Ursae Majoris System

Wright, E. L.; Skrutskie, Michael F.; Kirkpatrick, J. Davy; Gelino, Christopher R.; Griffith, R. L.; Marsh, K. A.; Jarrett, T. H.; Nelson, Matthew J.; Borish, H. Jacob; Mace, Gregory N.; Mainzer, A.; Eisenhardt, Peter; McLean, Ian S.; Tobin, John J.; Cushing, Michael C.

doi:10.1088/0004-6256/145/3/84

Cited by 314 publications

(133 citation statements)

References 52 publications

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“…To summarize briefly, the sample is selected from the Two Micron All Sky Survey (2MASS) catalog using a dereddened color cut of (J − K) 0 > 0.5 to remove hotter main sequence stars and to ensure that only stars with T eff 5500 K (for which stellar parameters and abundances can be accurately determined) are selected, but without biasing the sample against metal-poor stars. The dereddening is accomplished using the Rayleigh-Jeans Color Excess method (RJCE; Majewski et al 2011), which uses 2MASS photometry in conjunction with near-IR photometry from the Spitzer/IRAC (Fazio & Team 2004) GLIMPSE surveys (Benjamin et al 2003;Churchwell et al 2009) where available or from WISE (Wright et al 2010).…”

Section: Data and Sample Selectionmentioning

confidence: 99%

Chemical Cartography With Apogee: Large-Scale Mean Metallicity Maps of the Milky Way Disk

Hayden¹,

Holtzman²,

Bovy³

et al. 2014

173

195

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We present Galactic mean metallicity maps derived from the first year of the SDSS-III APOGEE experiment. Mean abundances in different zones of projected Galactocentric radius (0 < R < 15 kpc) at a range of heights above the plane (0 < |z| < 3 kpc), are derived from a sample of nearly 20,000 giant stars with unprecedented coverage, including stars in the Galactic mid-plane at large distances. We also split the sample into subsamples of stars with low-and high-[α/M] abundance ratios. We assess possible biases in deriving the mean abundances, and find that they are likely to be small except in the inner regions of the Galaxy. A negative radial metallicity gradient exists over much of the Galaxy; however, the gradient appears to flatten for R < 6 kpc, in particular near the Galactic mid-plane and for low-[α/M] stars. At R > 6 kpc, the gradient flattens as one moves off the plane, and is flatter at all heights for high-[α/M] stars than for low-[α/M] stars. Alternatively, these gradients can be described as vertical gradients that flatten at larger Galactocentric radius; these vertical gradients are similar for both low-and high-[α/M] populations. Stars with higher [α/M] appear to have a flatter radial gradient than stars with lower [α/M]. This could suggest that the metallicity gradient has grown steeper with time or, alternatively, that gradients are washed out over time by migration of stars.

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Section: Data and Sample Selectionmentioning

confidence: 99%

Chemical Cartography With Apogee: Large-Scale Mean Metallicity Maps of the Milky Way Disk

Hayden¹,

Holtzman²,

Bovy³

et al. 2014

173

195

View full text Add to dashboard Cite

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“…T dwarfs in higher order multiple systems are relatively rare, this being the fifth such system discovered after Gl 570 D (Burgasser et al 2000),Wolf 1130 B (Mace et al 2013), Ross 458 C (Goldman et al 2010) and ξ UMa E (Wright et al 2013). The central binary of 2MASS J0213+3648 has Hα and X-ray activity along with UV flaring, suggesting that it may be young (with the X-ray emission pointing towards it being younger than the Hyades).…”

Section: O N C L U S I O N Smentioning

confidence: 99%

“…Currently, there are 22 known T dwarf companions with separations greater than 100 au, the 21 listed in the literature review of Deacon et al (2014) plus the recently discovered companion to the exoplanet host star HIP 70849 (Lodieu et al 2014). Of these, four (Gl 570 D, Burgasser et al 2000; Wolf 1130 B, Mace et al 2013; Ross 458 C, Goldman et al 2010, and ξ UMa E, Wright et al 2013) lie in systems with higher order stellar multiplicity. Relatively few known T dwarfs companions lie in young systems.…”

mentioning

confidence: 99%

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

Deacon

Magnier

Liu

et al. 2017

Mon. Not. R. Astron. Soc.

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We present the discovery of a 360 AU separation T3 companion to the tight (3.1 AU) M4.5+M6.5 binary 2MASS J02132062+3648506. This companion was identified using Pan-STARRS 1 data and, despite its relative proximity to the Sun (22.2 +6.4 −4.0 pc; Pan-STARRS 1 parallax) and brightness (J=15.3), appears to have been missed by previous studies due to its position near a diffraction spike in 2MASS. The close M dwarf binary has active X-ray and Hα emission and shows evidence for UV flares. The binary's weak GALEX UV emission and strong Na I 8200 Å Na absorption leads us to an age range of ∼1-10 Gyr. Applying this age range to evolutionary models implies the wide companion has a mass of 0.063±0.009 M ⊙ . 2MASS J02132+3648 C provides a relatively old benchmark close to the L/T transition and acts as a key, older comparison to the much younger early-T companions HN Peg B and GU Psc b.

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“…A summary of discoveries prior to 2010 is presented in Faherty et al (2010). Since then wide-field surveys such as Sloan Digital Sky Survey (SDSS; Ahn et al 2012; see studies by Zhang et al 2010;Dhital et al 2010) and WISE (Wright et al 2010; see work by Luhman et al 2012;Wright et al 2013) have been used to identify wide companions to stars. As these surveys are either single epoch or taken over a short period of time, they often require additional data sets, such as Two Micron All Sky Survey (2MASS; Skrutskie et al 2006), to allow the identification of companions from their common proper motion with the primary.…”

Section: Introductionmentioning

confidence: 99%

WIDE COOL AND ULTRACOOL COMPANIONS TO NEARBY STARS FROM Pan-STARRS 1

Deacon

Liu

Magnier

et al. 2014

ApJ

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We present the discovery of 57 wide (>5 ) separation, low-mass (stellar and substellar) companions to stars in the solar neighborhood identified from Pan-STARRS 1 (PS1) data and the spectral classification of 31 previously known companions. Our companions represent a selective subsample of promising candidates and span a range in spectral type of K7-L9 with the addition of one DA white dwarf. These were identified primarily from a dedicated common proper motion search around nearby stars, along with a few as serendipitous discoveries from our Pan-STARRS 1 brown dwarf search. Our discoveries include 23 new L dwarf companions and one known L dwarf not previously identified as a companion. The primary stars around which we searched for companions come from a list of bright stars with well-measured parallaxes and large proper motions from the Hipparcos catalog (8583 stars, mostly A-K dwarfs) and fainter stars from other proper motion catalogs (79170 stars, mostly M dwarfs). We examine the likelihood that our companions are chance alignments between unrelated stars and conclude that this is unlikely for the majority of the objects that we have followed-up spectroscopically. We also examine the entire population of ultracool (>M7) dwarf companions and conclude that while some are loosely bound, most are unlikely to be disrupted over the course of ∼10 Gyr. Our search increases the number of ultracool M dwarf companions wider than 300 AU by 88% and increases the number of L dwarf companions in the same separation range by 82%. Finally, we resolve our new L dwarf companion to HIP 6407 into a tight (0. 13, 7.4 AU) L1+T3 binary, making the system a hierarchical triple. Our search for these key benchmarks against which brown dwarf and exoplanet atmosphere models are tested has yielded the largest number of discoveries to date.

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A T8.5 Brown Dwarf Member of the Ξ Ursae Majoris System

Cited by 314 publications

References 52 publications

Chemical Cartography With Apogee: Large-Scale Mean Metallicity Maps of the Milky Way Disk

Chemical Cartography With Apogee: Large-Scale Mean Metallicity Maps of the Milky Way Disk

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

WIDE COOL AND ULTRACOOL COMPANIONS TO NEARBY STARS FROM Pan-STARRS 1

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