J/PASP/118/659 RI photometry of 2MASS late M and L dwarfs (Liebert+, 2006)
RI photometry of 2MASS-selected late M and L dwarfs.
Liebert J., Gizis J.E.
<Publ. Astron. Soc. Pac., 118, 659-670 (2006)>
=2006PASP..118..659L 2006PASP..118..659L
ADC_Keywords: Stars, dwarfs ; Stars, late-type ; Photometry, infrared
Abstract:
We report R and I band observations for 201 late M and L dwarfs
selected on the basis of Two Micron All Sky Survey (Cat. II/246)
JHKs and photographic red colors, made with a telescope of modest
aperture. It is shown that deep surveys covering these red bands
can provide data sets that complement JHKs, permitting a fairly good
photometric classification system for L dwarfs. Due primarily to the
disappearance of strong TiO opacities, R-I reaches a maximum at late
M type and turns blueward for subtypes M9 to about L3. Apart from a
small plateau at L0-L2, the I-Ks color remains as a monotonic measure
of spectral type or temperature over this range, and likewise for M
dwarfs. For late L types, both colors probably get redder again,
although the accuracy of our data and number of objects do not give us
robust conclusions by L6-L8. It is also interesting to look at the
dispersions of the IJKs bands at a given spectral type. It is widely
believed that this dispersion is caused by object-to-object variations
in the amount, location, or other properties of dust or clouds. We
find a moderately larger spread for the J-Ks color than for I-J.
Description:
Observations were obtained using the Cassegrainfocus CCD imager at
the Cerro Tololo InterAmerican Observatory (CTIO) 1.5m telescope.
Observing runs were in 1999 March, May, and September and 2000 May.
Observations were made with the Kron-Cousins R and I filters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 84 201 *Observed Sample
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Note on table1.dat: On the 204 lines of the original version, they
were 3 duplicated lines, removed here.
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See also:
J/AJ/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
J/AJ/132/891 : Binaries among nearby L dwarfs (Reid+, 2006)
J/AJ/133/439 : Luminosity function of M7-L8 ultracool dwarfs (Cruz+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination sign (J2000)
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 23 F4.1 arcsec DEs Declination (J2000)
25- 30 F6.3 mag Rcmag ?=- Cousins R magnitude
32- 36 F5.3 mag e_Rcmag ?=- rms uncertainty on Rcmag
38- 43 F6.3 mag Icmag ?=- Cousins I magnitude
45- 49 F5.3 mag e_Icmag ?=- rms uncertainty on Icmag
51- 55 F5.3 mag Rc-Ic ? Cousins R-I colour index
57- 61 F5.2 mag Jmag 2MASS J magnitude
63- 67 F5.2 mag Hmag 2MASS H magnitude
69- 73 F5.2 mag Ks 2MASS Ks magnitude
75- 78 A4 --- SpType MK spectral type
80- 82 F3.1 --- e_SpType ? Error on SpType
84 I1 --- r_SpType ? Reference for SpType (1)
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Note (1): References as follows:
1 = Cruz et al., 2007, Cat. J/AJ/133/439 and
Cruz, 2004ApJ...604L..61C 2004ApJ...604L..61C
2 = Cruz et al., 2003, Cat. J/AJ/126/2421
3 = Reid et al., 2006, Cat. J/AJ/132/891
4 = Reid & Cruz, 2002AJ....123..466R 2002AJ....123..466R
5 = Kirkpatrick et al., 1999ApJ...519..802K 1999ApJ...519..802K
6 = Kirkpatrick et al., 2000AJ....120..447K 2000AJ....120..447K
7 = this paper
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Dec-2007