J/A+A/583/A122 Variability behaviour of CoRoT M-giant stars (Ferreira+, 2015)
The variability behaviour of CoRoT M-giant stars.
Ferreira Lopes C.E., Neves V., Leao I.C., De Freitas D.B.,
Canto Martins B.L., Da Costa A.D., Paz-Chinchon F., Das Chagas M.L.,
Baglin A., Janot-Pacheco E., De Medeiros J.R.
<Astron. Astrophys., 583, A122 (2015)>
=2015A&A...583A.122F 2015A&A...583A.122F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Stars, M-type ; Stars, variable ; Surveys ; Optical
Keywords: catalogs - stars: oscillations - stars: evolution
Abstract:
For six years the Convection, Rotation, and planetary Transits (CoRoT)
space mission has been acquiring photometric data from more than 100
000 point sources towards and directly opposite the inner and outer
regions of the Galaxy. The high temporal resolution of the CoRoT data,
combined with the wide time span of the observations, enabled the
study of short- and long-time variations in unprecedented detail.
The aim of this work is to study the variability and evolutionary
behaviour of M-giant stars using CoRot data.
From the initial sample of 2534 stars classified as M giants in the
CoRoT databases, we selected 1428 targets that exhibit well defined
variability, by visual inspection. Then, we defined three catalogues:
C1 - stars with Teff<4200K and LCs displaying semi-sinusoidal
signatures; C2 - rotating variable candidates with Teff>4200K; C3 -
long-period variable candidates (with LCs showing a variability period
up to the total time span of the observations). The variability period
and amplitude of C1 stars were computed using Lomb-Scargle and
harmonic fit methods. Finally, we used C1 and C3 stars to study the
variability behaviour of M-giant stars.
The trends found in the V-I vs. J-K colour-colour diagram are in
agreement with standard empirical calibrations for M giants. The
sources located towards the inner regions of the Galaxy are
distributed throughout the diagram, while the majority of the stars
towards the outer regions of the Galaxy are spread between the
calibrations of M giants and the predicted position for carbon stars.
The stars classified as supergiants follow a different sequence from
the one found for giant stars. We also performed a Kolmogorov-Smirnov
(KS) test of the period and amplitude of stars towards the inner and
outer regions of the Galaxy. We obtained a low probability that the
two samples came from the same parent distribution. The observed
behaviour of the period-amplitude and period-effective temperature
(Teff) diagrams are, in general, in agreement with those found for
Kepler sources and ground based photometry, with pulsation being the
dominant cause responsible for the observed modulation. We also
conclude that short-time variations on M-giant stars do not exist or
are very rare, and the few cases we found are possibly related to
biases or background stars.
Description:
Photometric parameters for 1435 M CoRot stars. For each star, CoRoT
IDs, coordinates, V, I, J, and Ks magnitudes, temperature, amplitude,
and period are provided. This table was performed seven years after
publication and hence minor errors can be found.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tables.dat 163 1435 Stellar parameters of C1, C2 and C3 samples
(tables 2-4)
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See also:
B/corot : CoRoT observation log (N2-4.4) (CoRoT 2016)
III/282 : CoRoT Bright Stars Catalogue with variability classes (Baglin+, 2015)
Byte-by-byte Description of file: tables.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- CoRoT CoRoT ID
13- 21 F9.5 deg RAdeg Right Ascension (J2000)
25- 32 F8.5 deg DEdeg Declination (J2000)
36- 43 A8 --- SpType CoRoT-Spectral type
50- 60 A11 --- LC CoRoT-luminosity class
64- 73 A10 --- Type Variable type
77- 81 F5.2 mag Vmag ?=- V magnitude
85- 89 F5.2 mag V0mag ?=- Deredenned V magnitude
93- 97 F5.2 mag Imag ?=- I magnitude
101-105 F5.2 mag I0mag ?=- Deredenned I magnitude
109-113 F5.2 mag Jmag J magnitude
117-121 F5.2 mag J0mag Deredenned J magnitude
125-129 F5.2 mag Kmag K magnitude
133-137 F5.2 mag K0mag ?=- Deredenned K magnitude
140-144 I5 K Teff ?=- Effective temperature
148-154 F7.3 d Per Period
158-163 F6.2 mmag Amp Amplitude
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Acknowledgements:
Carlos Ferreira Lopes, carlos.ferreira(at)uda.cl
(End) Patricia Vannier [CDS] 24-Oct-2022