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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tables.dat 164 26 26 nearby L and late-M dwarfs
(tables 2, 3, 6 and 7 of the paper)
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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
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Bytes Format Units Label Explanations
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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)
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Note (1): The spectroscopic indices are defined in
Martin et al. (1999AJ....118.2466M 1999AJ....118.2466M)
Note (2): The spectroscopic indices are defined in
Reid et al. (1995AJ....110.1838R 1995AJ....110.1838R)
Note (3): The VOa index is defined in
Kirkpatrick et al. (1999ApJ...519..802K 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 2002MNRAS.336L..49S
3 = Folkes et al., 2007MNRAS.378..901F 2007MNRAS.378..901F
4 = Hambaryan et al., 2004A&A...415..265H 2004A&A...415..265H
5 = Kendall et al., 2007MNRAS.374..445K 2007MNRAS.374..445K
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Acknowledgements:
Phan Bao Ngoc, pbngoc(at)asiaa.sinica.edu.tw
(End) Patricia Vannier [CDS] 27-Mar-2008