J/A+A/632/A95 Light curves of NGC 6910 pulsating stars (Mozdzierski+, 2019)
Ensemble asteroseismology of pulsating B-type stars in NGC 6910.
Mozdzierski D., Pigulski A., Kolaczkowski Z., Michalska G., Kopacki G.,
Carrier F., Walczak P., Narwid A., Steslicki M., Fu J.-N., Jiang X.-J.,
Zhang C., Jackiewicz J., Telting J., Morel T., Saesen S., Zahajkiewicz E.,
Brus P., Srodka P., Vuckovic M., Verhoelst T., Van Helshoecht V.,
Lefever K., Gielen C., Decin L., Vanautgaerden J., Aerts C.
<Astron. Astrophys. 632, A95 (2019)>
=2019A&A...632A..95M 2019A&A...632A..95M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, variable ; Photometry, CCD ;
Photometry, Geneva ; Stars, B-type
Keywords: asteroseismology - stars: oscillations - stars: early-type -
stars: fundamental parameters -
open clusters and associations: individual: NGC 6910
Abstract:
The aim of this study is to obtain the age of the open cluster NGC
6910 by means of ensemble asteroseismology of the early-type pulsating
members, to derive their stellar parameters, and to classify the
excited modes. We used time-series analysis, performed photometric and
spectroscopic mode identification, and calculated grids of
evolutionary and seismic models to apply the procedure of ensemble
asteroseismology for nine pulsating members of NGC 6910. With two
iterations of the procedure of ensemble asteroseismology we derived an
age of 10.6+0.9-0.8Myr for NGC 6910. We also identified the
degree l for 8 of 37 modes detected in these stars and classified all
modes in terms of p, g, and mixed-mode pulsations. Of the nine
pulsating stars examined in the paper, eight are β Cep stars,
including three that are hybrid β Cep and slowly pulsating B-type
(SPB) pulsators, and one is an SPB star. Interestingly, the least
massive β Cep star, NGC 6910-38, has a mass of about 5.6 solar
masses. The present theory does not predict unstable p modes in B-type
stars with such a low mass. The g modes with relatively high
frequencies (>3.5d-1), observed in three members of the cluster,
are also stable according to seismic modelling. Both findings pose a
challenge for theoretical calculations and prompt a revision of the
opacities. The procedure of ensemble asteroseismology was found to be
successful for NGC 6910 and χ Per on the basis of pulsating B-type
stars and can therefore be applied to other young open clusters that
are rich in such stars.
Description:
Light curves of 9 B-type pulsating stars, members of NGC 6910 open
cluster, are presented. The data was obtained in the Geneva U, Johnson
B and V, and Cousins I passbands during multi-site campaigns, and used
to perform the ensemble asteroseismology procedure. Details on
calibration, reduction, and analysis are described in the source
paper. Light curves include both 2005-2007 and 2013 campaigns. Their
systematic difference in average brightness is artificial.
Objects:
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RA (2000) DE Designation(s)
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20 23 08 +40 46.5 NGC 6910 = NGC 6910
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 73 9 List of the program pulsating stars
lc/* . 35 Individual UGBVI light curves of the program stars
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- WEBDA WEBDA number (1)
5- 6 I2 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 15 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
31- 36 F6.3 mag Vmag Johnson V magnitude
38- 46 A9 --- FileUG Name of the file with Geneva U photometry
in subdirectory lc
48- 55 A8 --- FileB Name of the file with Johnson B photometry
in subdirectory lc
57- 64 A8 --- FileV Name of the file with Johnson V photometry
in subdirectory lc
66- 73 A8 --- FileI Name of the file with Cousins I photometry
in subdirectory lc
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Note (1): Identification number from Becker & Stock (1949AN....277..233B 1949AN....277..233B,
NGC 6910 NNN in Simbad.
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Byte-by-byte Description of file: lc/*
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Bytes Format Units Label Explanations
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2- 14 F13.5 d HJD Heliocentric Julian Date
17- 24 F8.5 mag mag Differential magnitude
27- 32 F6.4 mag e_mag Error on magnitude
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Acknowledgements:
Dawid Mozdzierski, mozdzierski(at)astro.uni.wroc.pl
(End) Patricia Vannier [CDS] 12-Nov-2019