J/A+A/623/A127 Homogeneous sample of 34000 M7-M9.5 dwarfs (Ahmed+, 2019)
A homogeneous sample of 34 000 M7-M9.5 dwarfs brighter than J = 17.5
with accurate spectral types.
Ahmed S., Warren S.J.
<Astron. Astrophys. 623, A127 (2019)>
=2019A&A...623A.127A 2019A&A...623A.127A (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Stars, M-type ; Photometry, SDSS ; Photometry, infrared
Keywords: stars: low-mass - catalogs - surveys
Abstract:
The space density of late M dwarfs, sub-types M7 to M9.5, is not well
determined. We have applied the photo-type method of Skrzypek et al.
to iz photometry from SDSS and YJHK photometry from UKIDSS, over an
effective area of 3070deg2, to produce a new, bright J(Vega)<17.5,
homogeneous sample of 33665 M7 to M9.5 dwarfs. The typical S/N of
each source summed over the 6 bands is >100. Classifications are
provided to the nearest half spectral sub-type. Through comparison
with the classifications in the BUD spectroscopic sample of Schmidt et
al. (2010, Cat. J/AJ/139/1808), the typing is shown to be accurately
calibrated to the BUD classifications, with a precision better than
0.5 sub-types rms, i.e. is as precise as good spectroscopic
classification. Sources with large chisq>20 include several catalogued
late-type subdwarfs. The new sample of late M dwarfs is highly
complete, but there is a bias in the classification of rare peculiar
blue or red objects. For example L subdwarfs are misclassified towards
earlier types by approximately two spectral sub-types. We estimate
that this bias affects only ∼1% of sources. Therefore the sample is
well suited for measuring the luminosity function, as well as
investigating the softening towards the Galactic plane of the
exponential variation of density with height.
Description:
Table 1 provides details of the 33665 M7-M9.5 dwarfs selected from
SDSS+UKIDSS izYJHK photometry using the photo-type method. The table
includes coordinates, izYJHK photometry, spectral type (from
photo-type), goodness of fit, reddening, spectral type (from
spectroscopy, if available), distance, and Galactic (l, b)
coordinates.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 140 33665 List of M7-M9.5 dwarfs
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See also:
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [ULAS]
6- 24 A19 --- ULAS Source ULAS name, JHHMMSS.ss+DDMMSS.s,
UKIDSS-DR9, Lawrence et al., 2012, Cat. II/319
26- 29 F4.2 arcsec Angsep Angular separation UKIDSS/SDSS
31- 35 F5.2 mag imag SDSS i (in Vega)
37- 42 F6.2 mag e_imag SDSS i error (in Vega)
44- 48 F5.2 mag zmag SDSS z (in Vega)
50- 54 F5.2 mag e_zmag SDSS z error (in Vega)
56- 60 F5.2 mag Ymag UKIDSS Y (in Vega)
62- 65 F4.2 mag e_Ymag UKIDSS Y error (in Vega)
67- 71 F5.2 mag Jmag UKIDSS J (in Vega)
73- 76 F4.2 mag e_Jmag UKIDSS J error (in Vega)
78- 82 F5.2 mag Hmag UKIDSS H (in Vega)
84- 87 F4.2 mag e_Hmag UKIDSS H error (in Vega)
89- 93 F5.2 mag Kmag UKIDSS K (in Vega)
95- 98 F4.2 mag e_Kmag UKIDSS K error (in Vega)
100-104 A5 --- PhType Photo-type classification
106-111 F6.2 --- chi2 Chi2 value from photo-type classification
113-117 F5.3 --- E8 Reddening
119-120 A2 --- SpType ?=99 Spectral type given in literature (1)
122-126 F5.1 pc Dist Estimated distance
128-133 F6.2 deg GLON Galactic longitude
135-140 F6.2 deg GLAT Galactic latitude
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Note (1): 99 indicates no data available (spectral type).
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Acknowledgements:
Stephen Warren, s.j.warren(at)imperial.ac.uk
(End) S. Warren [Imperial College London], P. Vannier [CDS] 11-Mar-2019