J/A+A/660/A38 Ultracool dwarfs with spectra in LAMOST DR7 (Wang+, 2022) ================================================================================ Ultracool dwarfs identified with spectra in LAMOST DR7. Wang Y.-F., Luo A-L., Chen W.-P., Jones H.R.A., Du B., Li Y.-B., Zhang S., Bai Z.-R., Kong X., Guo Y.-X. =2022A&A...660A..38W (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Surveys ; Stars, dwarfs ; Stars, late-type ; Spectroscopy ; Optical Keywords: surveys - stars: low-mass - brown dwarfs - binaries: visual - stars: late-type Abstract: We identify 734 ultracool dwarfs having spectral type M6 or later including one L0, of which, 625 are having spectral observation for the first time with LAMOST. All these ultracool dwarfs are within 360 pc, with the Gaia G magnitude brighter than ~19.2mag. Studying the spectra and checking their stellar parameters (Teff, logg and [M/H]) derived with the LAMOST pipeline, we found their cool red nature and their metallicity consistent with being Galaxy thin disk objects. Furthermore, 77 of them show lithium absorption line at 6708{AA} indicating their young ages and substellar nature. Kinematics obtained through LAMOST radial velocities combining with the proper motion and parallax from Gaia EDR3, also suggest the majority of our targets are thin disk objects. Kinematic ages are estimated through the relationship between the velocity dispersion and the average age for a certain population. Moreover, 35 binaries are identified, among which 6 are reported as binaries for the first time. Description: 734 late-type M dwarfs identified visually from LAMOST DR7 are presented in Table 1. The atmospheric parameters(Teff, Logg, and M/H), radial velocity and signal to noise in SDSS i and z band, and radial velocity from LAMOST DR7 are presented in Table 2. We also listed the flag of the lithium strength in Table 2. In Table 3, we list the kinematic parameters calculated for 571 objects of our ultracool dwarf sample with radial velocity from LAMOST DR7, and photometry and astrometric from Gaia EDR3. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 173 734 The ultracool dwarfs table2.dat 102 734 Radial velocity and atmosphere parameters in LDR7 table3.dat 155 571 Kinematic parameters -------------------------------------------------------------------------------- See also: I/350 : Gaia EDR3 (Gaia Collaboration, 2020) http://dr7.lamost.org : LAMOST DR7 Home Page Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 5 I5 --- Seq [1/734] Running number 6- 15 A10 --- obsid LAMOST obsid 16- 27 F12.5 deg RAdeg Right ascension (J2000.0) 28- 39 F12.5 deg DEdeg Declination (J2000.0) 40- 44 A5 --- SpType1 Spectral type from LAMOST DR7 45- 64 A20 --- GaiaEDR3 Gaia EDR3 source_id 65- 74 F10.2 mas plx ?=-9999.99 parallax from Gaia EDR3 75- 84 F10.2 mas e_plx ?=-9999.99 uncertainty of parallax from Gaia EDR3 85- 94 F10.2 mas/yr pmRA ?=-9999.99 Proper motion in RA direction, pmRA*cosDE, from Gaia EDR3 95-104 F10.2 mas/yr e_pmRA ?=-9999.99 Uncertainty of proper motion in RA direction from Gaia EDR3 105-114 F10.2 mas/yr pmDE ?=-9999.99 Proper motion in Dec direction from Gaia EDR3 115-124 F10.2 mas/yr e_pmDE ?=-9999.99 Uncertainty of proper motion in Dec direction from Gaia EDR3 125-134 F10.3 --- RUWE ?=-9999.99 RUWE from Gaia EDR3 139-144 F6.3 mag Gmag G band magnitude from Gaia EDR3 145-154 F10.3 mag BPmag ?=-9999.99 BP band magnitude from Gaia EDR3 155-164 F10.3 mag RPmag ?=-9999.99 RP band magnitude from Gaia EDR3 165-173 A9 --- SpType2 Spectral type from the literature (SIMBAD) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- Seq [1/734] Running number 6- 14 F9.5 deg RAdeg Right ascension (J2000.0) 18- 26 F9.5 deg DEdeg Declination (J2000.0) 27- 34 F8.2 km/s RV ?=-9999 Radial velocity from LAMOST DR7 36- 40 I5 K Teff ?=-9999 Effective temperature from LAMOST DR7 42- 46 I5 K e_Teff ?=-9999 Uncertainty of effective temperature from LAMOST DR7 49- 56 F8.2 [cm/s2] logg ?=-9999.99 Surface gravity from LAMOST DR7 59- 66 F8.2 [cm/s2] e_logg ?=-9999.99 Uncertainty of surface gravity from LMAOST DR7 69- 76 F8.2 [-] MH ?=-9999.99 Metallicity from LAMOST DR7 79- 86 F8.2 [-] e_MH ?=-9999.99 Uncertainty of metallicity from LAMOST DR7 90 A1 --- Li [HMLN] Flag of the lithium strength (1) 94- 96 I3 --- SNRi Signal to noise ratio in SDSS i band from LAMOST DR7 98-102 I5 --- SNRz Signal to noise ratio in SDSS z band from LAMOST DR7 -------------------------------------------------------------------------------- Note (1): Flag of the lithium strength as follows: H = strong M = medium L = weak N = no -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- Seq [1/733] Running number 5- 13 F9.5 deg RAdeg Right ascension (J2000.0) 17- 25 F9.5 deg DEdeg Declination (J2000.0) 27- 33 F7.2 km/s U Galactic U velocity 36- 39 F4.2 km/s E_U Upper uncertainty of Galactic U velocity 43- 46 F4.2 km/s e_U Lower uncertainty of Galactic U velocity 48- 54 F7.2 km/s V Galactic V velocity 57- 60 F4.2 km/s E_V Upper uncertainty of Galactic V velocity 64- 67 F4.2 km/s e_V Lower uncertainty of Galactic V velocity 69- 75 F7.2 km/s W Galactic W velocity 77- 81 F5.2 km/s E_W Upper uncertainty of Galactic W velocity 84- 88 F5.2 km/s e_W Lower uncertainty of Galactic W velocity 90- 96 F7.2 pc zgal Galactic height 98-102 F5.2 pc E_zgal Upper uncertainty of Galactic height 105-109 F5.2 pc e_zgal Lower uncertainty of Galactic height 115-121 F7.2 pc rgal Distance to the Galactic center on the Galactic plane 124-128 F5.2 pc E_rgal Upper uncertainty of distance to the Galactic center on the Galactic plane 131-135 F5.2 pc e_rgal Lower uncertainty of distance to the Galactic center on the Galactic plane 138-145 F8.2 --- TDD ?=-9999.99 probability ratio of thick disk over disk 151-155 I5 --- TDH ?=-9999 probability ratio of thick disk over halo ------------------------------------------------------------------------------- Acknowledgements: Ali Luo, lal(at)bao.ac.cn ================================================================================ (End) Ali Luo [NAOC, China], Patricia Vannier [CDS] 28-Mar-2022