Meeting the Cool Neighbors. V. A 2MASS-Selected Sample of Ultracool Dwarfs

By Kelle Cruz, I. Neill Reid, J. Liebert, J. D. Kirkpatrick, P. Lowrance. 2003

341 citations recorded by the source corpus.

We present the initial results of our effort to create a statistically robust, volume-limited sample of ultracool dwarfs from the Two Micron All Sky Survey Second Incremental Data Release. We are engaged in a multifaceted search for nearby late-type objects, and this is the first installment of our search using purely photometric selection. The goal of this work is a determination of the low-mass star and brown dwarf luminosity function in the infrared. Here we outline the construction of the sample, dubbed 2MU2, and present our first results, including the discovery of 186 M7–L6 dwarfs—47 of which are likely to be within 20 pc of the Sun. These results represent 66% of the ultracool candidates in our sample yet constitute a 127% increase in the number of ultracool dwarfs known within the volume searched (covering 40% of the sky out to 20 pc). In addition, we have identified 10 M4–M6.5 objects that are likely to be within 20 pc (or within 1 σ). Finally, based on these initial data, we present a preliminary luminosity function and discuss several interesting features of the partial sample presented here. Once our sample is complete, we will use our measured luminosity function to constrain the mass function of low-mass stars and brown dwarfs.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/012c4dc190631112f877bcc7efd3d3a8027fd4e9

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In Astronomy and Astrophysics

1. Michael C. Liu
2. A. Burgasser
3. T. Dupuy
4. J. D. Kirkpatrick
5. Kelle Cruz
6. M. Marley
7. K. Luhman
8. K. Allers

In Instrumentation

1. Michael C. Liu
2. A. Burgasser
3. J. D. Kirkpatrick
4. T. Dupuy
5. Kelle Cruz
6. M. Marley
7. K. Allers
8. K. Luhman

Citations in the corpus

• THE EXTREMELY RED, YOUNG L DWARF PSO J318.5338−22.8603: A FREE-FLOATING PLANETARY-MASS ANALOG TO DIRECTLY IMAGED YOUNG GAS-GIANT PLANETS (2013, background): “5−22 was not discovered by previous large-area searches for L dwarfs using 2MASS (Reid et al. 2008; Cruz et al. 2003).”
• L′ and M′ Photometry of Ultracool Dwarfs (2004, background): “5 (Cruz et al. 2003) than its near-infrared spectral type of T0 (G02).”
• Binaries and the L Dwarf/T Dwarf Transition (2006, background): “57 041403.5 (hereafter SDSS 0423 0414; Geballe et al. 2002; Cruz et al. 2003), the near-infrared classification was retained.”
• BANYAN. II. VERY LOW MASS AND SUBSTELLAR CANDIDATE MEMBERS TO NEARBY, YOUNG KINEMATIC GROUPS WITH PREVIOUSLY KNOWN SIGNS OF YOUTH (2013, background): “2MASS J06195260–2903592 is an M6 dwarf unusually red for its spectral type and reported as having signs of low gravity in its optical spectrum by Cruz et al. (2003).”
• Subtle Signatures of Multiplicity in Late-type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839–0446358 (2008, methodology): “Cruz et al. (2003) esti- mate a distance of 26±4 pc for this source based on its classification and empirical MJ/spectral type relations.”
• The Solar Neighborhood. XVII. Parallax Results from the CTIOPI 0.9 m Program: 20 New Members of the RECONS 10 Parsec Sample (2006, background): “More recently, large-scale work by Reid and collaborators (Reid & Cruz 2002; Reid et al. 2002, 2003a, 2003b, 2004; Cruz & Reid 2002; Cruz et al. 2003; Reid 2003) has identified additional new systems from proper-motion compendia, and has reidentified and confirmedmany of the systems noted by others.”
• THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, methodology): “We measure a parallactic distance of 87.7+9.4−11.8 pc, with a kinematics-only BANYAN II analysis still indicating >99.9% Y.FLD. Cruz et al. (2003) noted that the object lies in the direction of the high-galactic latitude MBM20 (LDN 1642) cloud, which has an estimated distance of 124 ± 19 pc…”
• A Unified Near-Infrared Spectral Classification Scheme for T Dwarfs (2005, background): “Indeed, there appears to be a decoupling of optical and near infrared spectral morphologies among late-type L dwarfs and early-type T dwarfs that could be indicative of such dust/Teff effects (Cruz et al. 2003; Knapp et al. 2004).”
• DISCOVERIES FROM A NEAR-INFRARED PROPER MOTION SURVEY USING MULTI-EPOCH TWO MICRON ALL-SKY SURVEY DATA (2010, background): “These so called “blue L dwarfs” have unusually blue J −Ks colors for their optical spectral types and were first pointed out in follow-up of 2MASS sources by Gizis et al. (2000) and Cruz et al. (2003).”
• Preliminary Parallaxes of 40 L and T Dwarfs from the US Naval Observatory Infrared Astrometry Program (2004, background): “T transition object SDSS J042348−0414 has unusual spectral properties such that in the near–infrared Geballe et al. (2002) classify it as a T0, while in the optical Cruz et al. (2003) and Kirkpatrick et al. (2004) classify it as an L7.”
• A PATCHY CLOUD MODEL FOR THE L TO T DWARF TRANSITION (2010, background): “In addition to the L to T transition, patchy clouds have been suggested by Folkes et al. (2007) as a possible mechanism to explain those L dwarfs that have unusually blue nearinfrared colors (Cruz et al. 2003; Knapp et al. 2004; Burgasser et al. 2008).”
• PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, neutral): “′′3 (≈170 AU given its photometric distance of ≈20 pc), 2MASS J11240487+3808054 (Close et al. 2003; Cruz et al. 2003).”
• A SPECTROSCOPIC CATALOG OF THE BRIGHTEST (J < 9) M DWARFS IN THE NORTHERN SKY, (2012, background): “Most notably, the “Meet the Cool Neighbours” program (hereafter MCN) has determined spectral subtypes for several hundred M dwarfs identified from the Luyten catalogs but not listed in the CNS3 (Cruz & Reid 2002; Cruz et al. 2003; Reid et al. 2003, 2004; Cruz et al. 2007; Reid, Cruz, & Allen 2007).”