Discovery of a Bright Field Methane (T-Type) Brown Dwarf by 2MASS

Burgasser, Adam J.; Wilson, John C.; Kirkpatrick, J. Davy; Skrutskie, Michael F.; Colonno, Michael; Enos, A. T.; Smith, John David; Henderson, Christine; Gizis, John E.; Brown, Michael E.; Houck, J. R.

doi:10.1086/301475

Cited by 96 publications

(46 citation statements)

References 34 publications

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“…References. Albert et al (2011) [A11]; Artigau et al (2006) [A06]; Artigau et al (2010) [A10]; [B06]; Bouy et al (2003) [B03]; Burgasser et al (1999) [B99]; Burgasser et al (2000) [B00]; Burgasser et al (2003) [B02]; Burgasser et al (2003) [BK03]; Burgasser et al (2004) [B04]; Burgasser et al (2005) [B05]; Burgasser et al (2006) [BK06]; Burgasser et al (2008) [B08]; Burgasser et al (2010) [BC10]; Burningham et al (2010) [B10]; Chiu et al (2006) [C06]; Dahn et al (2002) [D02]; [D12]; Ellis et al (2005) [E05]; Faherty et al (2012) [F12]; Gelino et al (2002) [G02]; Hawley et al (2002) [H02]; Knapp et al (2004) [K04]; Leggett et al (2000) [L00]; Looper et al (2007) [L07]; Looper et al (2008) [L08]; Reid et al (2008) [R08]; Scholz et al (2003) [S03]; Scholz et al (2003) [S10]; Stumpf et al (2011) [S11]; Smart et al (2013) [S13]; Strauss et al (1999) [S99]; Tinney et al (2003) [T03]; Tinney et al (2005) [T05]; Vrba et al (2004) [V04]. …”

Section: Discussionmentioning

confidence: 99%

The brown dwarf atmosphere monitoring (BAM) project

Wilson

Rajan

Patience

2014

A&A

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Using the SofI instrument on the 3.5 m New Technology Telescope, we have conducted an extensive near-infrared monitoring survey of an unbiased sample of 69 brown dwarfs spanning the L0 to T8 spectral range, with at least one example of each spectral type. Each target was observed for a 2−4 h period in the J s -band, and the median photometric precision of the data is ∼0.7%. A total of 14 brown dwarfs were identified as variables with min-to-max amplitudes ranging from 1.7% to 10.8% over the observed duration. All variables satisfy a statistical significance threshold with a p-value ≤5% based on comparison with a median reference star light curve. Approximately half of the variables show pure sinusoidal amplitude variations similar to 2MASSJ2139+0220, and the remainder show multi-component variability in their light curves similar to SIMPJ0136+0933. It has been suggested that the L-T transition should be a region of a higher degree of variability if patchy clouds are present, and this survey was designed to test the patchy cloud model with photometric monitoring of both the L-T transition and non-transition brown dwarfs. The measured frequency of variables is 13 +10 −4 % across the L7−T4 spectral range, indistinguishable from the frequency of variables of the earlier spectral types (30 +11 −8 %), the later spectral types (13 +10 −4 %), or the combination of all non-transition region brown dwarfs (22 +7 −5 %). The variables are not concentrated in the transition, in a specific colour, or in binary systems. Of the brown dwarfs previously monitored for variability, only ∼60% maintained the state of variability (variable or constant), with the remaining switching states. The 14 variables include 9 newly identified variables that will provide important systems for follow-up multi-wavelength monitoring to further investigate brown dwarf atmosphere physics.

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Section: Discussionmentioning

confidence: 99%

The brown dwarf atmosphere monitoring (BAM) project

Wilson

Rajan

Patience

2014

A&A

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“…The spectra have been normalized to the flux at 5.4 μm and vertically offset in increments of 2 Jy. (Reiners & Basri 2008); (7) discovery by Martin et al (1999); (8) v sin i has been measured at 41 and 67 km s −1 (Zapatero Osorio et al 2006;Reiners & Basri 2008); (9) discovery by Leggett et al (2000); (10) v sin i has been measured at 28 km s −1 (Zapatero Osorio et al 2006); (11) discovery by Burgasser et al (2000); (12) v sin i has been measured at 23 km s −1 (Zapatero Osorio et al 2006). a Coordinates are sexagesimal with the following format: 2MASS Jhhmmssss ± ddmmsss, DENIS-P Jhhmmss.s ± hhmmss, and SDSS Jhhmmss.ss ± ddmmss.s.…”

Section: Data Acquisition and Reductionmentioning

confidence: 99%

THE 0.8-14.5 μm SPECTRA OF MID-L TO MID-T DWARFS: DIAGNOSTICS OF EFFECTIVE TEMPERATURE, GRAIN SEDIMENTATION, GAS TRANSPORT, AND SURFACE GRAVITY

Stephens

Leggett

Cushing

et al. 2009

ApJ

360

387

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We present new 5.2-14.5 μm low-resolution spectra of 14 mid-L to mid-T dwarfs. We also present new 3.0-4.1 μm spectra for five of these dwarfs. These data are supplemented by existing red and near-infrared spectra (∼0.6-2.5 μm), as well as red through mid-infrared spectroscopy of seven other L and T dwarfs presented by Cushing et al. We compare these spectra to those generated from the model atmospheres of Saumon & Marley. The models reproduce the observed spectra well, except in the case of one very red L3.5 dwarf, 2MASS J22244381−0158521. The broad wavelength coverage allows us to constrain almost independently the four parameters used to describe these photospheres in our models: effective temperature (T eff ), surface gravity, grain sedimentation efficiency (f sed ), and vertical gas transport efficiency (K zz ). The CH 4 bands centered at 2.2, 3.3, and 7.65 μm and the CO band at 2.3 μm are sensitive to K zz , and indicates that chemical mixing is important in all L and T dwarf atmospheres. The sample of L3.5 to T5.5 dwarfs spans the range 1800 K T eff 1000 K, with an L-T transition (spectral types L7 to T4) that lies between 1400 and 1100 K for dwarfs with typical near-infrared colors; bluer and redder dwarfs can be 100 K warmer or cooler, respectively, when using infrared spectral types. When using optical spectral types, the bluer dwarfs have more typical T eff values as they tend to have earlier optical spectral types. In this model analysis, f sed increases rapidly between types T0 and T4, indicating that increased sedimentation can explain the rapid disappearance of clouds at this stage of brown dwarf evolution. There is a suggestion that the transition to dust-free atmospheres happens at lower temperatures for lower gravity dwarfs.

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“…Since the discovery in 1995 of an old brown dwarf companion to a star (Nakajima et al 1995) and a few free-floating young brown dwarfs in the Pleiades cluster (Rebolo et al 1995), numerous isolated cold field brown dwarfs have been discovered by very wide field surveys like DENIS (DEep Near Infrared Survey Epchtein et al 1997;Delfosse et al 1997Delfosse et al , 1999Martín et al 1999;Kendall et al 2004), 2MASS (2 Microns All Sky Survey Skrutskie et al 2006;Kirkpatrick et al 1999;Burgasser et al 2000Burgasser et al , 2004, SDSS (Sloan Digital Sky Survey York et al 2000;Strauss et al 1999; with the National Science Foundation. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.…”

Section: Introductionmentioning

confidence: 99%

Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results

Delorme¹,

Willott

Forveille³

et al. 2008

A&A

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Aims. We present the first results of a wide field survey for cool brown dwarfs with the MegaCam camera on the CFHT telescope, the Canada-France Brown Dwarf Survey, hereafter CFBDS. Our objectives are to find ultracool brown dwarfs and to constrain the field-brown dwarf mass function thanks to a larger sample of L and T dwarfs. Methods. We identify candidates in CFHT/MegaCam i and z images using optimised psf-fitting within Source Extractor, and follow them up with pointed near-infrared imaging on several telescopes. Results. We have so far analysed over 350 square degrees and found 770 brown dwarf candidates brighter than z AB = 22.5. We currently have J-band photometry for 220 of these candidates, which confirms 37% as potential L or T dwarfs. Some are among the reddest and farthest brown dwarfs currently known, including an independent identification of the recently published ULAS J003402.77-005206.7 and the discovery of a second brown dwarf later than T8, CFBDS J005910.83-011401.3. Infrared spectra of three T dwarf candidates confirm their nature, and validate the selection process. Conclusions. The completed survey will discover ∼100 T dwarfs and ∼500 L dwarfs or M dwarfs later than M8, approximately doubling the number of currently known brown dwarfs. The resulting sample will have a very well-defined selection function, and will therefore produce a very clean luminosity function.

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Discovery of a Bright Field Methane (T-Type) Brown Dwarf by 2MASS

Cited by 96 publications

References 34 publications

The brown dwarf atmosphere monitoring (BAM) project

The brown dwarf atmosphere monitoring (BAM) project

THE 0.8-14.5 μm SPECTRA OF MID-L TO MID-T DWARFS: DIAGNOSTICS OF EFFECTIVE TEMPERATURE, GRAIN SEDIMENTATION, GAS TRANSPORT, AND SURFACE GRAVITY

Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results

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