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Ultracool SpeXtroscopic Survey. I. Volume-limited Spectroscopic Sample and Luminosity Function of M7−L5 Ultracool Dwarfs

Bardalez Gagliuffi, Daniella C. and Burgasser, Adam J. and Schmidt, Sarah J. and Theissen, Christopher and Gagné, Jonathan and Gillon, Michaël and Sahlmann, Johannes and Faherty, Jacqueline K. and Gelino, Christopher and Cruz, Kelle L. and Skrzypek, Nathalie and Looper, Dagny (2019) Ultracool SpeXtroscopic Survey. I. Volume-limited Spectroscopic Sample and Luminosity Function of M7−L5 Ultracool Dwarfs. Astrophysical Journal, 883 (2). Art. No. 205. ISSN 1538-4357. doi:10.3847/1538-4357/ab253d.

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We present a volume-limited, spectroscopically verified sample of M7−L5 ultracool dwarfs (UCDs) within 25 pc. The sample contains 410 sources, of which 93% have trigonometric distance measurements (80% from Gaia DR2) and 81% have low-resolution (R ~ 120), near-infrared (NIR) spectroscopy. We also present an additional list of 60 sources that may be M7−L5 dwarfs within 25 pc when distance or spectral-type uncertainties are taken into account. The spectra provide NIR spectral and gravity classifications, and we use these to identify young sources, red and blue J − K S color outliers, and spectral binaries. We measure very low gravity and intermediate-gravity fractions of 2.1^(+0.9)_(−0.8)% and 7.8^(+1.7)_(−1.5)%, respectively; fractions of red and blue color outliers of 1.4^(+0.6)_(−0.5)% and 3.6^(+1.0)_(−0.9)%, respectively; and a spectral binary fraction of 1.6^(+0.5)_(−0.5)%. We present an updated luminosity function for M7−L5 dwarfs continuous across the hydrogen-burning limit that agrees with previous studies. We estimate our completeness to range between 69% and 80% when compared to an isotropic model. However, we find that the literature late-M sample is severely incomplete compared to L dwarfs, with completeness of 62^(+8)_(−7)% and 83^(+10)_(−9)%, respectively. This incompleteness can be addressed with astrometric-based searches of UCDs with Gaia to identify objects previously missed by color- and magnitude-limited surveys.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bardalez Gagliuffi, Daniella C.0000-0001-8170-7072
Burgasser, Adam J.0000-0002-6523-9536
Schmidt, Sarah J.0000-0002-7224-7702
Theissen, Christopher0000-0002-9807-5435
Gagné, Jonathan0000-0002-2592-9612
Gillon, Michaël0000-0003-1462-7739
Sahlmann, Johannes0000-0001-9525-3673
Faherty, Jacqueline K.0000-0001-6251-0573
Cruz, Kelle L.0000-0002-1821-0650
Additional Information:© 2019 The American Astronomical Society. Received 2019 February 25; revised 2019 May 24; accepted 2019 May 24; published 2019 October 4. The authors thank telescope operators Brian Cabreira, Dave Griep, and Tony Matulonis at IRTF for their support during observations. D.B.G. and A.J.B. acknowledge funding support from the National Aeronautics and Space Administration under grant No. NNX15AI75G. This research has made heavy use of the VizieR catalog access tool and SIMBAD database, operated at CDS, Strasbourg, France. The original description of the VizieR service was published in Ochsenbein et al. (2000), and the SIMBAD astronomical database was published in Wenger et al. (2000). This publication makes use of data from the SpeX Prism Spectral Libraries, maintained by Adam Burgasser at This research has made use of the Washington Double Star Catalog maintained at the U.S. Naval Observatory. This research was worked on at the NYC Gaia DR2 Workshop at the Center for Computational Astrophysics of the Flatiron Institute in 2018 April. This research has benefited from the Ultracool RIZzo Spectral Library, maintained by Jonathan Gagné and Kelle Cruz. The authors acknowledge being on the traditional territory of the Lenape Nations and recognize that Manhattan continues to be the home to many Algonkian peoples. We give blessings and thanks to the Lenape people and Lenape Nations in recognition that we are carrying out this work on their indigenous homelands. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Software: Astropy (Astropy Collaboration et al. 2013), Astroquery (Ginsburg et al. 2018), BANYAN Σ (Gagné et al. 2018), Matplotlib (Hunter 2007), Pandas (McKinney 2013), SpeXtool (Cushing et al. 2004), SpeX Prism Library Analysis Toolkit (SPLAT; Burgasser & Splat Development Team 2017), Tool for OPerations on Catalogues and Tables (TOPCAT; Taylor 2005). Facility: IRTF (SpeX). -
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:astronomical databases: miscellaneous – binaries: close – binaries: general – brown dwarfs – infrared: stars – stars: fundamental parameters
Issue or Number:2
Record Number:CaltechAUTHORS:20191004-102758228
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Official Citation:Daniella C. Bardalez Gagliuffi et al 2019 ApJ 883 205
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99084
Deposited By: Tony Diaz
Deposited On:04 Oct 2019 17:43
Last Modified:16 Nov 2021 17:43

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