J/A+A/377/945 Variability and spectra of LMC giants (Cioni+ 2001)
Variability and spectral classification of LMC giants:
results from DENIS and EROS
Cioni M.-R.L., Marquette J.-B., Loup C., Azzopardi M., Habing H.J.,
Lasserre T., Lesquoy E.
<Astron. Astrophys. 377, 945 (2001)>
=2001A&A...377..945C 2001A&A...377..945C
ADC_Keywords: Magellanic Clouds ; Spectral types ; Stars, variable
Keywords: stars: evolution - late-type - variables: general - Magellanic Clouds
Abstract:
We present the first cross-identifications of sources in the
near-infrared DENIS survey and in the micro-lensing EROS survey in a
field of about 0.5 square degrees around the optical center (OC) of
the Large Magellanic Cloud. We analyze the photometric history of
these stars in the EROS data base and obtain light-curves for about
800 variables. Most of the stars are long period variables (Miras
and Semi-Regulars); a few Cepheids are also present. We also present
new spectroscopic data on 126 asymptotic giant branch stars in the OC
field, 30 previously known and 96 newly discovered by the DENIS
survey. The visible spectra are used to assign a carbon- (C-) or
oxygen-rich (O-rich) nature to the observed stars on the basis of the
presence of molecular bands of TiO, VO, CN, C2. For the remaining of
the stars we used the (J-KS) color to determine whether they are
O-rich or C-rich. Plotting Log(period) versus KS we find three very
distinct period-luminosity relations, mainly populated by Semi-Regular
stars of type a (SRa), b (SRb) and Mira variables. Carbon-rich stars
occupy mostly the upper part of these relations. We find that 65% of
the asymptotic giant branch population are long period variables
(LPVs).
Description:
File tablea2.dat contains the DENIS/EROS sources with a good
light-curve quality, classified in the present work, with observed
spectra.
File tablea3.data contains the spectral nature of the newly observed
DENIS sources, not included in tablea2.dat.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea2.dat 62 334 Classified DENIS/EROS sources
tablea3.dat 35 76 Spectral classification of DENIS sources
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See also:
II/228 : DENIS Catalogue toward Magellanic Clouds (DCMC) (Cioni+ 2000)
Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [DCMC] Catalog Acronym
6- 24 A19 --- DCMC DCMC (Cat. II/228) identifier
26- 30 I5 --- EROS EROS number
32- 38 F7.3 d Per Variability period
40- 42 I3 --- q Light-curve quality factor (1)
44- 45 I2 --- Class Class type (2)
47- 48 I2 --- quad EROS quadrant (3)
50 I1 --- SpType Spectral type code (4)
52- 62 A11 --- Notes Notes (5)
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Note (1): Quality of the variability:
Only sources with q>25 are considered to be variable.
Sources with q>50have generally a "good-quality'' light-curve.
Sources with 25<q<50 are clearly variable but their light curve is
rarely good enough to determine any periodicity.
Note (2): Class type:
0 : Cepheid
11 : Mira
13 : Mira with bump
15 : SRa
16 : SRa with bump
19 : SR
2 : SRb
Note (3): EROS quadrant:
1st digit: CCD number (from 1 to 4, see Fig. 1)
2nd digit: quadrant number (from 1 to 4 clockwise)
Note (4): Spectral type code:
0: not observed
1: C, carbon-rich star
2: M, oxygen-rich star
3: S, S star
Note (5): Blanco et al. (1980ApJ...242..938B 1980ApJ...242..938B) counterpart or longer period
in case of SRbs
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Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [DCMC] Catalog Acronym
6- 24 A19 --- DCMC DCMC (Cat. II/228) identifier
26 A1 --- SpType Spectral type code (1)
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Note (1): Spectral type code:
C: carbon-rich star
M: oxygen-rich star
S: S star
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Acknowledgements: Maria Rosa Cioni
(End) Patricia Bauer [CDS] 27-Aug-2001