Access to Astronomical Catalogues

J/MNRAS/383/831     New DENIS nearby L and late-M dwarfs       (Phan-Bao+, 2008)
Discovery of new nearby L and late-M dwarfs at low Galactic latitude from the
DENIS data base.
    Phan-Bao N., Bessell M.S., Martin E.L., Simon G., Borsenberger J., Tata R.,
    Guibert J., Crifo F., Forveille T., Delfosse X., Lim J., De Batz B.
   <Mon. Not. R. Astron. Soc., 383, 831-844 (2008)>
   =2008MNRAS.383..831P
ADC_Keywords: Stars, nearby ; Stars, M-type ; Photometry, infrared ;
              Stars, distances ; Proper motions
Keywords: techniques: photometric - techniques: spectroscopic -
          stars: low-mass, brown dwarfs -
          stars: luminosity function, mass function - solar neighbourhood

Abstract:
    We report on new nearby L and late-M dwarfs (dphot≤30pc)
    discovered in our search for nearby ultracool dwarfs (I-J≥3.0,
    later than M8.0) in the Galactic plane (|b|<15°) over 4800
    deg2 in the Deep Near Infrared Survey of t he Southern Sky (DENIS)
    data base. We used late-M (≥M8.0), L and T dwarfs with accurate
    trigonometric parallaxes to calibrate the MJ versus I-J
    colour-luminosity relation. The resulting photometric distances have
    standard errors of ∼15 per cent, which we used to select candidates
    dphot ≤30pc. We measured proper motions from multi-epoch images
    found in the public archives ALADIN, DSS, 2MASS and DENIS, with at
    least three distinct epochs and time baselines of 10-21yr. We then
    used the Maximum Reduced Proper Motion method to select 28 candidates
    as ultracool dwarfs (M8.0-L8.0) and to reject one as a distant red
    star. Our low-resolution optical spectra confirmed that 26 were indeed
    ultracool dwarfs, with spectral types from M8.0 to L5.5. Two
    contaminants and one rejected by the maximum reduced proper motion
    cut-off were all reddened F-K main sequence stars. 20 of these 26
    ultracool dwarfs are new nearby ultracool dwarf members, three L
    dwarfs within 15pc with one L3.5 at only ∼10pc.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
tables.dat       164       26   26 nearby L and late-M dwarfs
                              (tables 2, 3, 6 and 7 of the paper)


See also:
          B/denis : The DENIS database (DENIS Consortium, 2005)
   J/AJ/123/3409  : SDSS M, L, and T dwarfs (Hawley+, 2002)
   J/AJ/126/2421  : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
   J/AJ/126/2449  : Nearby ultracool dwarfs in galactic plane (Reid+, 2003)
   J/AJ/127/3553  : JHK mag and spectroscopy for L and T dwarfs (Knapp+, 2004)
   J/AJ/133/439   : Luminosity function of M7-L8 ultracool dwarfs (Cruz+, 2007)
   J/A+A/380/590  : 30 DENIS late-M dwarfs between 15 and 30pc (Phan-Bao+, 2001)
   J/A+A/401/959  : 35 DENIS late-M dwarfs between 10 and 30pc (Phan-Bao+, 2003)
   J/A+A/441/653  : 32 DENIS nearby red dwarfs (Crifo+, 2005)
   J/A+A/446/515  : Distances of nearby ultracool dwarfs (Phan-Bao+, 2006)


Byte-by-byte Description of file: tables.dat

   Bytes Format Units       Label   Explanations

   1- 15  A15   ---         DENIS   DENIS name (based on J2000 position)
  17- 18  I2    h           RAh     Right ascension (J2000)
  20- 21  I2    min         RAm     Right ascension (J2000)
  23- 27  F5.2  s           RAs     Right ascension (J2000)
      29  A1    ---         DE-     Declination sign (J2000)
  30- 31  I2    deg         DEd     Declination (J2000)
  33- 34  I2    arcmin      DEm     Declination (J2000)
  36- 39  F4.1  arcsec      DEs     Declination (J2000)
  41- 45  F5.2  mag         Imag    DENIS I magnitude
  47- 50  F4.2  mag         I-J     DENIS I-J colour index
  52- 55  F4.2  mag         J-K     DENIS J-K colour index
  57- 60  F4.2  mag         e_Imag  DENIS I magnitude error
  62- 65  F4.2  mag         e_Jmag  DENIS J magnitude error
  67- 70  F4.2  mag         e_Kmag  DENIS K magnitude error
  72- 77  F6.3  arcsec/yr   pmRA    Proper motion in right ascension
  79- 83  F5.3  arcsec/yr   e_pmRA  pmRA error
  85- 90  F6.3  arcsec/yr   pmDE    Proper motion in declination
  92- 96  F5.3  arcsec/yr   e_pmDE  pmDE error
  98-102  F5.2  ---         PC3     The PC3 spectral index (1)
 104-107  F4.2  ---         e_PC3   PC3 error
 109-113  F5.3  ---         TiO5    The TiO5 spectral index (2)
 115-119  F5.3  ---         e_TiO5  TiO5 error
 121-124  F4.2  ---         VOa     The VOa spectral index (3)
 126-129  F4.2  ---         e_VOa   VOa error
 131-134  A4    ---         SpType  Adopted spectral type
 136-140  F5.2  mag         JMAG    Absolute J band magnitude
 142-145  F4.1  pc          Dist    Estimated distance from JMAG
 147-149  F3.1  pc          e_Dist  Dist error
 151-153  I3    km/s        Vt      Tangential velocity
 155-156  I2    km/s        e_Vt    Vt error
 158-161  F4.1  0.1nm       EWHa    Halpha equivalent width (in Angstroem)
     162  A1    ---         n_EWHa  [*] * when EWHa is an upper limit
     164  I1    ---         Ref     ? Reference for previously discovered
                                      ultracool dwarfs (4)

Note (1): The spectroscopic indices are defined in
           Martin et al. (1999AJ....118.2466M)
Note (2): The spectroscopic indices are defined in
           Reid et al. (1995AJ....110.1838R)
Note (3): The VOa index is defined in
           Kirkpatrick et al. (1999ApJ...519..802K)
Note (4): References are numbered as follows:
      1 = Cruz et al., 2003, Cat. J/AJ/126/2421
      2 = Scholz & Meusinger, 2002MNRAS.336L..49S
      3 = Folkes et al., 2007MNRAS.378..901F
      4 = Hambaryan et al., 2004A&A...415..265H
      5 = Kendall et al., 2007MNRAS.374..445K


Acknowledgements:
    Phan Bao Ngoc, pbngoc(at)asiaa.sinica.edu.tw
(End)                                      Patricia Vannier [CDS]    27-Mar-2008