J/MNRAS/341/534 J-type carbon stars in LMC (Morgan+, 2003)
J-type carbon stars in the Large Magellanic Cloud.
Morgan D.H., Cannon R.D., Hatzidimitriou D., Croke B.F.W.
<Mon. Not. R. Astron. Soc. 341, 534 (2003)>
=2003MNRAS.341..534M 2003MNRAS.341..534M
ADC_Keywords: Magellanic Clouds ; Stars, carbon ; Photometry, infrared
Keywords: stars: carbon - Magellanic Clouds
Abstract:
A sample of 1497 carbon stars in the Large Magellanic Cloud (LMC) has
been observed in the red part of the spectrum with the 2dF facility on
the Anglo-Australian Telescope. Of these, 156 have been identified as
J-type (i.e. 13C-rich) carbon stars using a technique which provides
a clear distinction between J stars and the normal N-type carbon stars
that comprise the bulk of the sample, and yields few borderline cases.
A simple two-dimensional classification of the spectra, based on their
spectral slopes in different wavelength regions, has been constructed
and found to be related to the more conventional c and j indices,
modified to suit the spectral regions observed. Most of the J stars
form a photometric sequence in the K-(J-K) colour-magnitude diagram,
parallel to and 0.6mag fainter than the N-star sequence. A subset of
the J stars (about 13 per cent) are brighter than this J-star
sequence; most of these are spectroscopically different from the other
J stars. The bright J stars have stronger CN bands than the other
J stars and are found strongly concentrated in the central regions of
the LMC. Most of the rather few stars in common with Hartwick and
Cowley's sample (1988ApJ...334..135H 1988ApJ...334..135H) of suspected CH stars are J
stars. Overall, the proportion of carbon stars identified as J stars
is somewhat lower than has been found in the Galaxy. The Na D lines
are weaker in the LMC J stars than in either the Galactic J stars or
the LMC N stars, and do not seem to depend on temperature.
Description:
Most of the carbon stars observed with 2dF were selected from the
newly completed catalogue of 7760 carbon stars by (Kontizas et al.,
2001, Cat. J/A+A/369/932, hereafter KDMK01).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 49 156 J stars in the Large Magellanic Cloud
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See also:
B/2mass : The 2MASS database (IPAC/UMass, 2000)
B/denis : The DENIS database (Epchtein+, 1999)
J/A+A/369/932 : RI photometry of LMC carbon stars (Kontizas+, 2001)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [KDM2001] KDM number, Kontizas et al., J/A+A/369/932
6- 10 F5.2 mag Rcmag ?=0.00 Kron-Cousins R magnitude (from KDMK01)
12- 16 F5.2 mag Icmag ?=0.00 Kron-Cousins I magnitude (from KDMK01)
18- 22 F5.2 mag Jmag ?=0.00 J magnitude (from 2MASS or DENIS)
24- 28 F5.2 mag Hmag ?=0.00 H magnitude (from 2MASS)
(0.00 indicates DENIS photometry for J and K)
30- 34 F5.2 mag Kmag ?=0.00 K magnitude (from 2MASS or DENIS)
36 I1 --- Group [1/6] J spectral group number
38- 40 F3.1 --- cindex Carbon c index (1)
42- 44 F3.1 --- jindex Isotopic j index (Keenan, 1993PASP..105..905K 1993PASP..105..905K) (2)
46 I1 --- 13C13C [0/2] Code denoting the strength of the
13C13C λ6144 band (3)
48- 49 A2 --- Note [+ *] Note (4)
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Note (1): The c index is derived from atomic lines seen in the blue.
It depends on the strong (0,0) and (0,1) Swan bands
at 5165 and 5635Å.
Note (2): The j index is based on the ratios of the bands
13C12C λ6168 to 12C12C λ6192,
13C12C λ6102 to 12C12C λ6122 and
13C14N λ6260 to 12C14N λ6206.
Note (3): Code as follows:
0 = undetected
1 = moderate
2 = strong
Note (4): Notes as follows:
+ = weaker spectra, with counts at the 6200Å peak less than 600
++ = weaker spectra, with counts at the 6200Å peak less than 300
* = a cross-identification noted below:
KDM 1688 = WORC 70
KDM 1751 = WORC 74
KDM 1814 = WORC 78 = CRW 6-6 = HC 185
KDM 2419 = WORC 101
KDM 2518 = WORC 106 = HC 160
CRW: Crabtree, Richer & Westerlund (1976ApJ...203L..81C 1976ApJ...203L..81C)
HC: Hartwick & Cowley (1988ApJ...334..135H 1988ApJ...334..135H, [HC88] NNN) and
Cowley & Hartwick (1991ApJ...373...80C 1991ApJ...373...80C)
WORC: Westerlund et al. (1978A&AS...31...61W 1978A&AS...31...61W)
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History:
From electronic version of the journal
(End) Patricia Bauer [CDS] 24-Jun-2003