A NEAR-INFRARED SPECTROSCOPIC STUDY OF YOUNG FIELD ULTRACOOL DWARFS

By K. Allers, Michael C. Liu. 2013

220 citations recorded by the source corpus.

We present a near-infrared (0.9–2.4 μm) spectroscopic study of 73 field ultracool dwarfs having spectroscopic and/or kinematic evidence of youth (≈10–300 Myr). Our sample is composed of 48 low-resolution (R ≈ 100) spectra and 41 moderate-resolution spectra (R ≳ 750–2000). First, we establish a method for spectral typing M5–L7 dwarfs at near-IR wavelengths that is independent of gravity. We find that both visual and index-based classification in the near-IR provides consistent spectral types with optical spectral types, though with a small systematic offset in the case of visual classification at J and K band. Second, we examine features in the spectra of ∼10 Myr ultracool dwarfs to define a set of gravity-sensitive indices based on FeH, VO, K i, Na i, and H-band continuum shape. We then create an index-based method for classifying the gravities of M6–L5 dwarfs that provides consistent results with gravity classifications from optical spectroscopy. Our index-based classification can distinguish between young and dusty objects. Guided by the resulting classifications, we propose a set of low-gravity spectral standards for the near-IR. Finally, we estimate the ages corresponding to our gravity classifications.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/500fdc304f952307a0312751827e976820afa315

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Citations in the corpus

THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, methodology): “2MASS J03552337+1133437 (L5γ/L3 vl-g): This object has the reddest J −K color in our sample, and both Cruz et al. (2009) and Allers & Liu (2013a) characterize it as very low gravity.”
The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs (2020, background): “…2008, (113) Liebert, et al. 2003, (114) Schneider, et al. 2014, (115) Cruz, et al. 2003, (116) Golimowski et al. 2004, (117) Reid, et al. 2006, (118) Allers & Liu 2013, (119) Castro et al. 2013, (120) Cruz, et al. 2007, (121) Fan, et al. 2000, (122) Geballe, et al. 2002, (123) Salim, et al. 2003,…”
BANYAN. VII. A NEW POPULATION OF YOUNG SUBSTELLAR CANDIDATE MEMBERS OF NEARBY MOVING GROUPS FROM THE BASS SURVEY (2015, methodology): “TABLE 5 — Continued 2MASS Spectral Equivalent Widths (Å) Spectral Indices (Allers & Liu 2013) Designation Type Na I 1.138µm K I 1.169µm K I 1.177µm K I 1.244µm K I 1.253µm FeHZ VOZ FeHJ KIJ H–cont 05181131–3101529 M7β 7.0±0.9 1.7±0.7 3.0±0.9 1.7±0.7 1.8±0.6 1.08±0.01 1.04±0.01 1.08±0.01 1.05±0.01 1.”
FUNDAMENTAL PARAMETERS AND SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG AND FIELD AGE OBJECTS WITH MASSES SPANNING THE STELLAR TO PLANETARY REGIME (2015, methodology): “New NIR and MIR Spectra We present new low-resolution SpeX Prism data for 2MASSI J1017075+130839, 2MASS J23224684-3133231, and 2MASS J05012406-0010452 taken on UT 2011 December 08, 2006 August 28, and 2007 October 12, respectively.”
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, methodology): “5−22 using the Allers & Liu (2013) system, which provides gravity-insensitive types consistent with optical spectral types.”
PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, methodology): “Compared to younger L0 objects from Allers & Liu (2013) in Figure 8, the blue side of the Hband of 1RXS J034231.”
Discovery of a warm, dusty giant planet around HIP 65426 (2017, background): “…variety of reference low-resolution spectra of late-M and L dwarfs compiled from the literature (Burgasser 2014; Best et al. 2015; Mace et al. 2013; Allers & Liu 2013) as well as spectra of young imaged exoplanets and brown dwarfs close to the L/T transition (Patience et al. 2010; Zurlo et al.…”
CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS (2015, background): “It has also been classified as a single M7 Ve star from optical spectra (Cruz et al. 2003; Reid et al. 2003; Gatewood & Coban 2009; Reiners & Basri 2009), but as an M6 V with surface gravity consistent with normal field dwarfs from near-infrared spectra (Allers & Liu 2013).”
THE GEMINI/NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF PLANETS AROUND YOUNG MOVING GROUP STARS (2013, unknown): “5 (Allers & Liu 2013; Dupuy & Liu 2012).”
BANYAN. II. VERY LOW MASS AND SUBSTELLAR CANDIDATE MEMBERS TO NEARBY, YOUNG KINEMATIC GROUPS WITH PREVIOUSLY KNOWN SIGNS OF YOUTH (2013, background): “Allers & Liu (2013) classified this object as VL-G.”