J/AJ/127/2838 Faint high-latitude carbon stars SDSS photometry (Downes+, 2004)
Faint high-latitude carbon stars discovered by the Sloan Digital Sky Survey:
an initial catalog.
Downes R.A., Margon B., Anderson S.F., Harris H.C., Knapp G.R.,
Schroeder J., Schneider D.P., York D.G., Pier J.R., Brinkmann J.
<Astron. J., 127, 2838-2849 (2004)>
=2004AJ....127.2838D 2004AJ....127.2838D
ADC_Keywords: Stars, carbon ; Stars, faint ; Photometry, SDSS ;
Photometry, infrared
Keywords: astrometry - stars: carbon - stars: statistics - surveys
Abstract:
A search of more than 3000deg2 of high-latitude sky by the Sloan
Digital Sky Survey has yielded 251 faint high-latitude carbon stars
(FHLCs), the large majority previously uncatalogued. We present
homogeneous spectroscopy, photometry, and astrometry for the sample.
The objects lie in the 15.6<r<20.8 range and exhibit a wide variety of
apparent photospheric temperatures, ranging from spectral types near M
to as early as F. Proper-motion measurements for 222 of the objects
show that at least 50%, and quite probably more than 60%, of these
objects are actually low-luminosity dwarf carbon (dC) stars, in
agreement with a variety of recent, more limited investigations that
show that such objects are the numerically dominant type of star with
C2 in the spectrum. This SDSS homogeneous sample of ∼110 dC stars
now constitutes 90% of all known carbon dwarfs and will grow by
another factor of 2-3 by the completion of the survey. As the spectra
of the dC and the faint halo giant C stars are very similar (at least
at spectral resolution of 103), despite a difference of 10mag in
luminosity, it is imperative that simple luminosity discriminants
other than proper motion be developed. We use our enlarged sample of
FHLCs to examine a variety of possible luminosity criteria, including
many previously suggested, and find that, with certain important
caveats, JHK photometry may segregate dwarfs and giants.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 251 Faint High-Latitude Carbon Stars Discovered in SDSS
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See also:
http://www.sdss.org : the SDSS Catalog Home Page
J/AJ/126/2579 : SDSS quasar catalog. II. First data release (Schneider+, 2003)
J/AJ/124/1651 : Faint high-latitude carbon stars SDSS photometry (Margon+ 2002)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS SDSS name (1)
26- 32 F7.2 --- Epoch ? Epoch of the observation (2)
34- 38 F5.2 mag rmag SDSS r-band magnitude (3)
39 A1 --- f_rmag [gh] Flag on rmag (4)
41- 44 F4.2 mag u-g ? SDSS (u-g) color
46- 49 F4.2 mag g-r ? SDSS (g-r) color
51- 54 F4.2 mag r-i ? SDSS (r-i) color
56- 60 F5.2 mag i-z ? SDSS (i-z) color
62- 66 F5.2 mag J-H ? The (J-H) color
68- 72 F5.2 mag H-K ? The (H-K) color
74- 77 F4.2 mag r-J ? The (r-J) color
79- 83 F5.1 mas/yr mu ? Proper motion
85- 88 F4.1 mas/yr e_mu ? The 1 σ error in mu
90- 94 F5.1 deg PA ? Position angle
96 A1 --- Class Object class (5)
98- 99 I2 --- f_Class ? Flag on Class (6)
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Note (1): As per normal convention, coordinate names are truncated rather
than rounded; precise astrometry is available in the SDSS archive.
Note (2): Epochs provided for those objects with proper motions detected
with 3 σ or greater significance.
Note (3): An approximate transformation to the Cousins I magnitude,
derived empirically from a comparison of SDSS observations of multiple
standard stars with published broadband photometry (Grebel, 2004,
Priv. Comm.), is Ic=-0.333(r-i) + i - 0.443. Note that this
transformation is not optimized for the specific case of C stars.
Note (4): Flag on rmag as follows:
g = Poor photometry: gmag given for crude guidance;
h = Poor photometry.
Note (5): Object class takes the following values:
D = Dwarf;
G = Giant;
U = Uncertain;
NULL = No data.
Note (6): Flags on Class take the following values:
1 = "F/G carbon star";
2 = Possible "F/G carbon star";
3 = Poorly calibrated spectrum;
4 = FASST 2; see Hendon & Stone, 1998, Cat. J/AJ/115/296
5 = RASS and FIRST source nearby;
6 = LP 587-45;
7 = Composite;
8 = Variable?;
9 = Candidate extragalactic object (see Paper I, Margon et al.,
Cat. J/AJ/124/1651);
10 = N-type; see Totten & Irwin (1998MNRAS.294....1T 1998MNRAS.294....1T) and
Hendon & Stone , 1998, Cat. J/AJ/115/296
11 = RASS source (QSO) nearby;
12 = In Draco dwarf galaxy (BASV 461);
13 = In Draco dwarf galaxy (Draco C-1); symbiotic variable; ROSAT source;
14 = In Draco dwarf galaxy (BASV 578);
15 = In Draco dwarf galaxy?
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 08-Jul-2004