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J/ApJ/833/96 Hawaii infrared parallax program. II. Ultracool dwarfs (Liu+, 2016)

The Hawaii infrared parallax program. II. Young ultracool field dwarfs. Liu M.C., Dupuy T.J., Allers K.N. <Astrophys. J., 833, 96-96 (2016)> =2016ApJ...833...96L (SIMBAD/NED BibCode)
ADC_Keywords: Spectral types; Parallaxes, trigonometric; Proper motions; Photometry, infrared; Magnitudes, absolute; Stars, brown dwarf Keywords: astrometry; brown dwarfs; parallaxes planets and satellites: gaseous planets; stars: distances stars: low-mass Abstract: We present a large, uniform analysis of young (∼10-150Myr) ultracool dwarfs, based on new high-precision infrared (IR) parallaxes for 68 objects. We find that low-gravity (VL-G) late-M and L dwarfs form a continuous sequence in IR color-magnitude diagrams, separate from the field population and from current theoretical models. These VL-G objects also appear distinct from young substellar (brown dwarf and exoplanet) companions, suggesting that the two populations may have a different range of physical properties. In contrast, at the L/T transition, young, old, and spectrally peculiar objects all span a relatively narrow range in near-IR absolute magnitudes. At a given spectral type, the IR absolute magnitudes of young objects can be offset from ordinary field dwarfs, with the largest offsets occurring in the Y and J bands for late-M dwarfs (brighter than the field) and mid-/late-L dwarfs (fainter than the field). Overall, low-gravity (VL-G) objects have the most uniform photometric behavior, while intermediate gravity (INT-G) objects are more diverse, suggesting a third governing parameter beyond spectral type and gravity class. We examine the moving group membership for all young ultracool dwarfs with parallaxes, changing the status of 23 objects (including 8 previously identified planetary-mass candidates) and fortifying the status of another 28 objects. We use our resulting age-calibrated sample to establish empirical young isochrones and show a declining frequency of VL-G objects relative to INT-G objects with increasing age. Notable individual objects in our sample include high-velocity (≳100km/s) INT-G objects, very red late-L dwarfs with high surface gravities, candidate disk-bearing members of the MBM20 cloud and β Pic moving group, and very young distant interlopers. Finally, we provide a comprehensive summary of the absolute magnitudes and spectral classifications of young ultracool dwarfs, using a combined sample of 102 objects found in the field and as substellar companions to young stars. Description: Since 2007, we have been carrying out a high-precision parallax program at the 3.6m CFHT using the facility wide-field IR camera WIRCam. We began observing the majority of the 67 ultracool objects of the sample presented here in mid-2009, except for SDSS J2249+0044AB, which was started in mid-2008, and several objects that we added to our program during 2010-2013. Images were obtained in J band for most of our targets, while brighter targets at risk of saturating in the WIRCam minimum integration time (5s) were observed in a narrow K-band filter (KH2) centered at 2.122um. We obtained high-S/N NIR spectra for five of our targets in order to assign spectral types and assess surface gravity. We used the NASA Infrared Telescope Facility on the summit of Mauna Kea, Hawaii, with the spectrograph SpeX (R∼150). We obtained resolved imaging of DENIS J1441.6-0945AB on 2014 March 14 UT using the facility camera NIRC2 in concert with the laser guide star adaptive optics (LGS AO) system on the Keck II telescope. We used the standard Mauna Kea Observatories (MKO) filters J, H, and K in addition to the NIRC2 Y-band filter. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 131 67 Summary of CFHT/WIRCam observed sample table2.dat 155 67 *CFHT/WIRCam parallax and proper-motion results table6.dat 169 104 Photometry for our sample and other potentially young objects table7.dat 230 104 Absolute magnitudes for our sample and other potentially young objects refs.dat 84 155 References
Note on table2.dat: This table gives all the astrometric parameters derived from our MCMC analysis for each target. Relative values are our directly fitted results. Absolute values include a correction for the mean parallax and proper motion of our reference stars, which includes an additional uncertainty added in quadrature to our direct fitting results (see Section 2.2).
See also: V/144 : NIR spectroscopy of low-mass binaries and brown dwarfs (Mace, 2014) II/328 : AllWISE Data Release (Cutri+ 2013) I/322 : UCAC4 Catalogue (Zacharias+, 2012) II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) J/ApJ/814/118 : L/T transition dwarfs search with PS1+WISE. II. (Best+, 2015) J/MNRAS/454/593 : Young moving groups in solar neighbourhood (Bell+, 2015) J/ApJ/810/158 : M,L,T dwarfs parameters and SEDs (Filippazzo+, 2015) J/ApJS/219/33 : BANYAN. VII. Candidate YMG members from BASS (Gagne+, 2015) J/AJ/149/158 : The BUD sample. I. L dwarf activity sample (Schmidt+, 2015) J/ApJ/798/73 : BANYAN All-Sky Survey (BASS) catalog. V. YMGs (Gagne+, 2015) J/A+A/567/A52 : Membership in stellar kinematic groups (Klutsch+, 2014) J/AJ/147/146 : Spectroscopy of Tuc-Hor candidate members (Kraus+, 2014) J/ApJ/786/29 : Catalog of distances to molecular clouds (Schlafly+, 2014) J/AJ/147/94 : Solar neighborhood. XXXII. L and M dwarfs (Dieterich+, 2014) J/ApJ/784/156 : Plx for 1507 nearby mid-to-late M dwarfs (Dittmann+, 2014) J/A+A/563/A125 : L1642 Herschel maps (Malinen+, 2014) J/AJ/147/34 : SpeX library of L-type dwarfs (Schneider+, 2014) J/AJ/146/156 : APOGEE M-dwarf survey. I. 1st yr veloc. (Deshpande+, 2013) J/ApJ/777/160 : NIR imaging for planets around MG stars (Biller+, 2013) J/PASP/125/809 : New nearby M, L, and T dwarfs (Thompson+, 2013) J/ApJS/205/6 : T dwarf population revealed by WISE (Mace+, 2013) J/ApJ/762/88 : Young stellar kinematic group candidate members (Malo+, 2013) J/A+A/547/A13 : Homogeneous sample of F6-K4 Hyades stars (Tabernero+, 2012) J/ApJ/758/56 : Young M dwarfs within 25pc. II. Kinematics (Shkolnik+, 2012) J/AJ/144/99 : Near-IR spectroscopy of 36 late M dwarfs (Deshpande+, 2012) J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012) J/ApJ/752/56 : BDKP. III. Plx for 70 ultracool dwarfs (Faherty+, 2012) J/AJ/143/80 : R Low-mass stars of beta Pic & AB Dor (Schlieder+, 2012) J/A+A/539/A143 : Nearby B-stars parameters and abundances (Nieva+, 2012) J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011) J/ApJ/723/684 : NIRSPEC ultracool dwarf radial velocity survey (Blake+, 2010) J/A+A/522/A112 : i'z' photom. of L5 and later dwarf candidates (Reyle+, 2010) J/ApJS/190/100 : NIR proper motion survey using 2MASS (Kirkpatrick+, 2010) J/AJ/139/1808 : Colors and kinematics of SDSS L dwarfs (Schmidt+, 2010) J/A+A/512/A37 : Velocities of 43 nearby L dwarfs (Seifahrt+, 2010) J/ApJ/710/1142 : SpeX spectroscopy of low mass binaries. I. (Burgasser+, 2010) J/ApJ/705/1416 : Sample of M7-M9.5 dwarfs <20pc (Reiners+, 2009) J/ApJ/699/649 : Young M dwarfs within 25pc. I. (Shkolnik+, 2009) J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009) J/A+A/493/L27 : Parallaxes of 10 ultracool subdwarfs (Schilbach+, 2009) J/ApJ/689/1295 : Lithium test implications for BDs (Kirkpatrick+, 2008) J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008) J/ApJ/676/1281 : L and T dwarfs in 2MASS/SDSS (Metchev+, 2008) J/A+A/481/661 : Hyades brown dwarfs and very low mass stars (Bouvier+, 2008) J/MNRAS/384/1399 : Proper motions of field L and T dwarfs (Jameson+, 2008) J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008) J/AJ/134/2340 : Membership of Praesepe & Coma Berenices (Kraus+, 2007) J/AJ/133/2258 : Activity and kinematics of ultracool dwarfs (Schmidt+, 2007) J/AJ/133/439 : Luminosity function of M7-L8 ultracool dwarfs (Cruz+, 2007) J/AJ/132/891 : Binaries among nearby L dwarfs (Reid+, 2006) J/AJ/131/2722 : New L and T dwarfs from the SDSS (Chiu+, 2006) J/ApJ/637/1067 : NIR spectral classification of T dwarfs (Burgasser+, 2006) J/other/ARA+A/43.195 : L and T dwarf stars (Kirkpatrick, 2005) J/other/ARA+A/42.685 : Young stars near the Sun (Zuckerman+, 2004) J/AJ/127/3553 : JHK photometry & spectroscopy for L & T dwarfs (Knapp+, 2004) J/AJ/127/2856 : Brown dwarfs in the 2MASS Survey (Burgasser+, 2004) J/AJ/126/3007 : Spectroscopy of faint red NLTT dwarfs (Reid+, 2003) J/AJ/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003) J/AJ/126/1526 : IR photometry of ultracool dwarfs (Bouy+, 2003) J/MNRAS/342/1241 : Low-mass stars in M45 and M44 (Pinfield+, 2003) J/AJ/125/3302 : HST binary very low mass stars & brown dwarfs (Gizis+, 2003) J/AJ/123/3409 : SDSS M, L, and T dwarfs (Hawley+, 2002) J/MNRAS/328/45 : Late-type stars members of young groups (Montes+, 2001) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1 A1 --- f_Name Flag on Name (1) 3- 28 A26 --- Name Target name 30 A1 --- n_Name [ac-e] Note on Name (2) 32- 41 A10 --- SpT Optical spectral type (3) 43 A1 --- f_SpT [D] Flag on SpT (4) 45- 53 A9 --- SpTir NIR spectral type (3) 55 A1 --- f_SpTir [Db] Flag on SpTir (4) 57- 60 A4 --- Filt Filter ("J" or "K_H2") 62- 65 F4.2 arcsec FWHM [0.5/0.9] Median full width at half maximum measured for the science target over all epochs 67- 70 F4.2 arcsec e_FWHM [0.04/0.3] rms of the FWHM 72- 76 F5.3 --- DelAMx [0.01/0.2] Maximum difference in airmass over all epochs (ΔAMmax) 78- 80 I3 --- Nfr [39/308] Total number of frames obtained 82- 83 I2 --- Nep [6/15] Number of distinct observing epochs (i.e. nights) 85- 88 F4.2 yr Delt [1.2/6.2] Time baseline Δt 90- 93 I4 --- Nref [20/1192] Number of reference stars (S/N>10) used 95- 97 I3 --- Ncal [14/248] Subset of reference stars used in the absolute astrometric calibration (5) 99-102 F4.2 mas dpi [0.2/1.6] offset from relative to absolute parallax (πabsrel) (6) 104-107 F4.2 mas e_dpi [0.02/0.2] dpi uncertainty 109-131 A23 --- Ref Reference(s) (see refs.dat file)
Note (1): Flag as follows: y = Objects with spectroscopic signatures of youth (low gravity, lithium); 40 objects c = Young stars with companions; 3 objects m = Candidate stellar association members; 11 objects p = Unusually red and/or peculiar ultracool dwarfs; 8 objects h = Strong Hα emitters; 3 objects s = Serendipitous parallaxes; 2 objects. Note (2): Flag as follows: a = aka 2MASS J04221413+1530525. c = aka TWA 28. d = aka TWA 26. e = Subsequent reobservation of this source by us indicates that the source may not be systematically red for its spectral type (see the Appendix). Note (3): Spectrally peculiar objects are denoted by "p." For the M5-L7 objects, all the NIR spectral types are based on the Allers & Liu (2013ApJ...772...79A) system, which has an intrinsic uncertainty of ±1 subclass. Note (4): Flag as follows: D = Objects that have been noted in the literature to have spectral signatures of youth but lacking a formal gravity classification. b = Integrated-light spectral types are listed for these unresolved binary targets. Note (5): Ncal is the subset of reference stars used in the absolute astrometric calibration (i.e., those available in 2MASS or the Sloan Digital Sky Survey). Note (6): computed for each field using the Besancon model of the Galaxy (Robin+ 2003A&A...409..523R), as described in Section 2.2.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 26 A26 --- Name Target name 28- 38 F11.7 deg RAdeg Right ascension in decimal degrees (Eq=J2000) 40- 50 F11.7 deg DEdeg Declination in decimal degrees (Eq=J2000) 52- 59 F8.2 d Epoch The first epoch of our observations; Modified Julian Date 61- 66 F6.4 arcsec Plx [0.002/0.2] Relative parallax 68- 73 F6.4 arcsec e_Plx [0.0008/0.004] Plx uncertainty 75- 81 F7.4 arcsec/yr pmRA [-0.8/0.8] Relative proper motion along RA (µα,relcosδ) 83- 88 F6.4 arcsec/yr e_pmRA [0.0004/0.003] pmRA uncertainty 90- 96 F7.4 arcsec/yr pmDE [-0.8/0.5] Relative proper motion along DE 98-103 F6.4 arcsec/yr e_pmDE [0.0004/0.006] pmDE uncertainty 105-110 F6.4 arcsec PlxA [0.003/0.2] Absolute parallax 112-117 F6.4 arcsec e_PlxA [0.0008/0.004] PlxA uncertainty 119-125 F7.4 arcsec/yr pmRAA [-0.8/0.8] Absolute proper motion along RA (µα,abscosδ) 127-132 F6.4 arcsec/yr e_pmRAA [0.0005/0.004] pmRAA uncertainty 134-140 F7.4 arcsec/yr pmDEA [-0.8/0.5] Absolute proper motion along DE 142-147 F6.4 arcsec/yr e_pmDEA [0.0006/0.006] pmDEA uncertainty 149-152 F4.1 --- Chi2 [4.2/29.6] The lowest χ2 in each set of MCMC chains 154-155 I2 --- dof [7/25] Degree of freedom
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 24 A24 --- Name Object name (1) 26 A1 --- n_AName [a] Flag on Name (G2) 28- 33 F6.2 mas Plx [3.4/259.3] Parallax 35- 38 F4.2 mas e_Plx [0.05/5] Plx uncertainty 40- 41 I2 --- n_Plx [1/55] Reference (2) 43- 47 F5.2 mag Ymag [8.9/19]? MKO Y-band magnitude 49- 52 F4.2 mag e_Ymag [0.02/0.4]? Ymag uncertainty 53 A1 --- f_Ymag Flag on Ymag (G1) 55- 59 F5.2 mag Jmag [8.3/20]? MKO J-band magnitude 61- 64 F4.2 mag e_Jmag [0.01/0.6]? Jmag uncertainty 65 A1 --- f_Jmag Flag on Jmag (G1) 67- 71 F5.2 mag Hmag [7.9/20.3] MKO H-band magnitude 73- 76 F4.2 mag e_Hmag [0.01/0.3] Hmag uncertainty 77 A1 --- f_Hmag Flag on Hmag (G1) 79- 83 F5.2 mag Kmag [7.5/19.3]? MKO K-band magnitude 85- 88 F4.2 mag e_Kmag [0.01/0.3]? Kmag uncertainty 89 A1 --- f_Kmag Flag on Kmag (G1) 91- 95 F5.2 mag Jmag2 [8.3/20]? J-band magnitude in 2MASS system 97-100 F4.2 mag e_Jmag2 [0.01/0.6]? Jmag2 uncertainty 101 A1 --- f_Jmag2 Flag on Jmag2 (G1) 103-107 F5.2 mag Hmag2 [7.8/20.2] H-band magnitude in 2MASS system 109-112 F4.2 mag e_Hmag2 [0.02/0.3] Hmag2 uncertainty 113 A1 --- f_Hmag2 Flag on Hmag2 (G1) 115-119 F5.2 mag Ksmag [7.5/19.2]? Ks-band magnitude in 2MASS system 121-124 F4.2 mag e_Ksmag [0.01/0.3]? Ksmag uncertainty 125 A1 --- f_Ksmag Flag on Ksmag (G1) 127-131 F5.2 mag W1mag [7/16.1]? AllWISE W1-band magnitude 133-136 F4.2 mag e_W1mag [0.02/0.08]? W1mag uncertainty 138-142 F5.2 mag W2mag [6.9/14.8]? AllWISE W2-band magnitude 144-147 F4.2 mag e_W2mag [0.02/0.08]? W2mag uncertainty 149-169 A21 --- Ref1 Reference(s) (see refs.dat file)
Note (1): The 2MASS J0253+3206 on line #15 was in fact 2MASS J0241-0326; corrected by CDS. Note (2): Reference as follows: 1 = This work (66 occurrences) 19 = Dieterich et al. 2014, J/AJ/147/94 20 = Dittmann et al. 2014, J/ApJ/784/156 21 = Ducourant et al. 2008A&A...477L...1D 22 = Ducourant et al. 2014A&A...563A.121D 23 = Dupuy & Liu 2012, J/ApJS/201/19 24 = Dupuy et al. 2016ApJ...827...23D 26 = Faherty et al. 2012, J/ApJ/752/56 27 = Gatewood & Coban 2009AJ....137..402G 42 = Marocco et al. 2013AJ....146..161M 51 = Riedel et al. 2014, J/AJ/147/85 52 = van Leeuwen 2007, I/311 53 = Vrba et al. 2004AJ....127.2948V 54 = Wahhaj et al. 2011ApJ...729..139W 55 = Weinberger et al. 2013ApJ...762..118W
Byte-by-byte Description of file: table7.dat
Bytes Format Units Label Explanations
1- 5 A5 --- OType Group of object (3) 7- 30 A24 --- Name Object name 32 A1 --- n_AName [a] Flag on Name (G2) 34- 43 A10 --- SpT Optical spectral type (4) 45- 54 A10 --- SpTir NIR spectral type (4) 56- 73 A18 --- Ref2 Reference(s) 75- 79 F5.2 --- YMag [6.2/17.4]? MKO absolute Y-band magnitude 81- 84 F4.2 --- e_YMag [0.04/1.2]? YMag uncertainty 85 A1 --- f_YMag Flag on Ymag (G1) 87- 91 F5.2 --- JMag [5.4/18.4]? MKO absolute Y-band magnitude 93- 96 F4.2 --- e_JMag [0.03/1.2]? JMag uncertainty 97 A1 --- f_JMag Flag on JMag (G1) 99-103 F5.2 --- HMag [4.7/19] MKO absolute Y-band magnitude 105-108 F4.2 --- e_HMag [0.03/1.2] HMag uncertainty 109 A1 --- f_HMag Flag on HMag (G1) 111-115 F5.2 --- KMag [4.2/18.1]? MKO absolute Y-band magnitude 117-120 F4.2 --- e_KMag [0.02/1.2]? KMag uncertainty 121 A1 --- f_KMag Flag on KMag (G1) 123-127 F5.2 --- JMag2 [5.5/18.7]? 2MASS absolute J-band magnitude 129-132 F4.2 --- e_JMag2 [0.03/1.2]? JMag2 uncertainty 133 A1 --- f_JMag2 Flag on JMag2 (G1) 135-139 F5.2 --- HMag2 [4.7/19] 2MASS absolute H-band magnitude 141-144 F4.2 --- e_HMag2 [0.03/1.2] HMag2 uncertainty 145 A1 --- f_HMag2 Flag on HMag2 (G1) 147-151 F5.2 --- KsMag [4.2/18]? 2MASS absolute Ks-band magnitude 153-156 F4.2 --- e_KsMag [0.02/1.2]? KsMag uncertainty 157 A1 --- f_KsMag Flag on KsMag (G1) 159-163 F5.2 --- W1Mag [3.8/15.7]? AllWISE absolute W1 band magnitude 165-168 F4.2 --- e_W1Mag [0.03/1.2]? W1Mag uncertainty 170-174 F5.2 --- W2Mag [3.2/13.6]? AllWISE absolute W2 band magnitude 176-179 F4.2 --- e_W2Mag [0.02/1.2]? W2Mag uncertainty 181-203 A23 --- Notes Notes (5) 205-230 A26 --- AName Complete name as given in tables 1 and 2 (the observed sample); column added by CDS
Note (3): Group as follows: VL-G = Very Low Gravity Objects (30 objects) INT-G = Intermediate Gravity Objects (19 objects) Oth-G = Other Low-gravity Objects (18 objects) Red = Unusually Red FLD-G Objects (8 objects) Young = Other Young Companions (10 objects) Misc = Miscellaneous (19 objects) Note (4): Spectrally peculiar objects are denoted by "p," and spectral types uncertain by ±1, ±1.5, and ±2 subclasses are denoted by ":", ":." and "::" respectively. For the M5-L7 objects with Allers & Liu (2013ApJ...772...79A) gravity classifications, the intrinsic uncertainty in the spectral type is ±1 subclass. Note (5): Notes are given indicating young group membership status and other attributes. Question marks indicate unlikely but potentially viable candidate members, and parentheses indicate probable members lacking RV confirmation (see Table 14). Pleiades MG, Hyades MG, and UMa MG are looser associations proposed elsewhere in the literature that were not part of our kinematic analysis and do not correspond to the actual Pleiades, Hyades, or Ursa Majoris clusters.
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Ref Reference code 5- 23 A19 --- BibCode Bibcode of the reference 25- 46 A22 --- Auth Author's name(s) 48- 84 A37 --- Comm Comment
Global notes: Note (G1): Flag as follows: s = synthesized values: for objects with NIR spectra and some published JHK photometry, we calculate 2MASS-MKO conversions and Y-J colors directly from that object's spectrum. o = For objects without spectra, we estimate 2MASS-MKO conversions based on the values for other objects expected to be of similar spectral type. Note (G2): a = Alternate names: SO J0253+1652=SO J025300.5+165258 (Teegarden's star), GJ 3276 (2MASS J0422+1530=2MASS J04221413+1530525), SSSPM J1102-3431 (TWA 28), 2MASS J1139-3159=2MASSW J1139511-315921 (TWA 26), 2MASS J1207-3932=2MASSW J1207334-393254 (TWA 27), DENIS J1245-4429=DENIS J124514.1-442907 (TWA 29).
History: From electronic version of the journal References: Dupuy & Liu Paper I. 2012ApJS..201...19D Cat. J/ApJS/201/19
(End) Emmanuelle Perret [CDS] 25-Jun-2018
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