THE BROWN DWARF KINEMATICS PROJECT (BDKP). III. PARALLAXES FOR 70 ULTRACOOL DWARFS
By Jacqueline K. Faherty, A. Burgasser, F. Walter, N. S. van der Bliek, M. Shara, Kelle Cruz, Andrew A. West, F. Vrba, G. Anglada-Escudé. 2012
176 citations recorded by the source corpus.
We report parallax measurements for 70 ultracool dwarfs (UCDs) including 11 late-M, 32 L, and 27 T dwarfs. In this sample, 14 M and L dwarfs exhibit low surface gravity features, 6 are close binary systems, and 2 are metal-poor subdwarfs. We combined our new measurements with 114 previously published UCD parallaxes and optical–mid-IR photometry to examine trends in spectral-type/absolute magnitude, and color–color diagrams. We report new polynomial relations between spectral type and MJHK. Including resolved L/T transition binaries in the relations, we find no reason to differentiate between a “bright” (unresolved binary) and a “faint” (single source) sample across the L/T boundary. Isolating early T dwarfs, we find that the brightening of T0–T4 sources is prominent in MJ where there is a [1.2–1.4] mag difference. A similar yet dampened brightening of [0.3–0.5] mag happens at MH and a plateau or dimming of [−0.2 to −0.3] mag is seen in MK. Comparison with evolutionary models that vary gravity, metallicity, and cloud thickness verifies that for L into T dwarfs, decreasing cloud thickness reproduces brown dwarf near-IR color–magnitude diagrams. However we find that a near constant temperature of 1200 ±100 K along a narrow spectral subtype of T0–T4 is required to account for the brightening and color–magnitude diagram of the L-dwarf/T-dwarf transition. There is a significant population of both L and T dwarfs which are red or potentially “ultra-cloudy” compared to the models, many of which are known to be young indicating a correlation between enhanced photospheric dust and youth. For the low surface gravity or young companion L dwarfs we find that 8 out of 10 are at least [0.2–1.0] mag underluminous in MJH and/or MK compared to equivalent spectral type objects. We speculate that this is a consequence of increased dust opacity and conclude that low surface gravity L dwarfs require a completely new spectral-type/absolute magnitude polynomial for analysis.
Subfields: Astronomy and Astrophysics, Instrumentation
View Paper: https://www.semanticscholar.org/paper/cee2afa66758478db037e3fcf6d696f6be5f8d81
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Citations in the corpus
- THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, methodology): “(See Section 3 for a discussion of the highly discrepant parallax from Faherty et al. 2012.)”
- Global Climate and Atmospheric Composition of the Ultra-hot Jupiter WASP-103b from HST and Spitzer Phase Curve Observations (2018, methodology): “For 1320+0409 we used SDSS, WISE and 2MASS photometry along with the optical spectrum from Reid et al. (2008), the near in- frared spectrum from Bardalez Gagliuffi et al. (2014), and the parallax reported in Faherty et al. (2012).”
- BAYESIAN ANALYSIS TO IDENTIFY NEW STAR CANDIDATES IN NEARBY YOUNG STELLAR KINEMATIC GROUPS (2012, background): “Faherty et al. (2012) have measured the trigonometric distance of this object and this mesurement confirms its membership to this group.”
- The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs (2020, background): “Those objects are discussed below: • 2MASS 0103+1935: This optical L6 dwarf (Kirkpatrick et al. 2000) has two independent parallax measurements, both low quality, of 35.9±5.7 mas (Table 6) and 46.9±7.6 mas (Faherty et al. 2012).”
- The Formation and Early Evolution of Low-Mass Stars and Brown Dwarfs (2012, methodology): “…are probably underestimated, which may partially explain why young L dwarfs are underluminous compared to normal dwarfs in near-IR bands (Faherty et al. 2012) and why the sequences of young clusters on H-R diagrams are underluminous relative to model iscohrones at the latest types…”
- NEGLECTED CLOUDS IN T AND Y DWARF ATMOSPHERES (2012, unknown): “Color-Magnitude Diagrams In Figure 9, we plot the photometric colors in the nearinfrared of all brown dwarfs with measured parallaxes and apparentJ andK magnitude errors smaller than 0.2 magnitudes (Dupuy & Liu 2012; Faherty et al. 2012).”
- BANYAN. VII. A NEW POPULATION OF YOUNG SUBSTELLAR CANDIDATE MEMBERS OF NEARBY MOVING GROUPS FROM THE BASS SURVEY (2015, methodology): “…longer wavelengths, causing young BDs to display similar absolute J magnitudes to those of field BDs around spectral type ∼L0, as well as absolute J magnitudes even fainter than those of field dwarfs at later spectral types (Faherty et al. 2012, 2013; Liu et al. 2013a; Zapatero Osorio et al. 2014).”
- Individual Dynamical Masses of Ultracool Dwarfs (2017, background): “…association of NLTT 20346 to the 2MASS J0850+1057 system is questionable (see Section 6.4 of Dupuy & Liu 2012), and the discovery and characterization of young late-L dwarfs indicates that they tend to be fainter at J-band, not brighter (Faherty et al. 2012; Liu et al. 2013a; Liu et al. 2016).”
- FUNDAMENTAL PARAMETERS AND SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG AND FIELD AGE OBJECTS WITH MASSES SPANNING THE STELLAR TO PLANETARY REGIME (2015, methodology): “…ultracool dwarfs are sensitive to age (Kirkpatrick et al. 2006, 2008; Cruz et al. 2009; Faherty et al. 2009; Allers et al. 2010; Bihain et al. 2010; Faherty et al. 2012; Schmidt et al. 2010), we derived one polynomial for the field age objects (MFLD) and a separate one for objects with signatures…”
- BANYAN. II. VERY LOW MASS AND SUBSTELLAR CANDIDATE MEMBERS TO NEARBY, YOUNG KINEMATIC GROUPS WITH PREVIOUSLY KNOWN SIGNS OF YOUTH (2013, methodology): “Faherty et al. (2012) measure a trigonometric distance of 39.0±14.0 pc for this object.”