J/MNRAS/372/69 VR light curves of M2 variables (Lazaro+, 2006)
CCD photometry of the globular cluster M2: RR Lyrae physical parameters
and new variables
Lazaro C., Arellano Ferro A., Arevalo A., Bramich D.M., Giridhar S.,
Poretti E.
<Mon. Not. R. Astron. Soc., 372, 69-80 (2006)>
=2006MNRAS.372...69L 2006MNRAS.372...69L
ADC_Keywords: Clusters, globular ; Stars, variable ; Photometry, CCD
Keywords: stars: horizontal branch - stars: Population II -
stars: variables: other - globular clusters: individual: M2
Abstract:
We report the results of CCD V and R photometry of the RR Lyrae stars
in M2. The periodicities of most variables are revised and new
ephemerides are calculated. Light-curve decomposition of the RR Lyrae
stars was carried out and the corresponding mean physical parameters
[Fe/H]=-1.47, Teff=6276K, logL=1.63L☉ and MV=0.71 from nine
RRab and [Fe/H]=-1.61, M=0.54M☉, Teff=7215K, logL=1.74L☉
and MV=0.71 from two RRc stars were calculated. A comparison of the
radii obtained from the above luminosity and temperature with
predicted radii from non-linear convective models is discussed. The
estimated mean distance to the cluster is 10.49±0.15kpc. These
results place M2 correctly in the general globular cluster sequences
for Oosterhoff type, mass, luminosity and temperature, all as a
function of the metallicity. Mean relationships for M, logL/L☉,
Teff and MV as a function of [Fe/H] for a family of globular clusters
are offered. These trends are consistent with evolutionary and
structural notions on the horizontal branch. Eight new variables are
reported.
Description:
Time-series V and R photometry for the variable stars in M2 (NGC7089).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
stars.dat 52 42 Summary of observed stars (from table3)
varphot.dat 39 3314 CCD time-series V and R photometry of
30 variables in M2 (NGC7089)
--------------------------------------------------------------------------------
See also:
J/AJ/117/2868 : BV photometry in M2 (NGC 7089) (Lee+, 1999)
V/97 : Updated 3rd Cat Variable Stars in Globular Clusters (Clement+ 1997)
http://www.astro.utoronto.ca/~cclement/read.html : Christine Clement's
Catalogue of Variable Stars in Galactic Globular Clusters
Byte-by-byte Description of file: stars.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- VName Variable star number
5- 6 A2 --- RRt RR Lyr variability type (ab or c) (1)
9- 10 I2 h RAh Right Ascension J2000 (hours)
12- 13 I2 min RAm Right Ascension J2000 (minutes)
15- 19 F5.2 s RAs Right Ascension J2000 (seconds)
21 A1 --- DE- Declination J2000 (sign)
22- 23 I2 deg DEd Declination J2000 (degrees)
25- 26 I2 arcmin DEm Declination J2000 (minutes)
28- 31 F4.1 arcsec DEs Declination J2000 (seconds)
34- 41 F8.5 d Per Period (1)
44- 52 F9.3 d T0 ? Epoch (JD-2400000) (1)
--------------------------------------------------------------------------------
Note (1): only for stars V35 to V42 studied here.
The positions and periods for stars 1 to 34 are from Christine Clement's
page for M2 at: http://www.astro.utoronto.ca/~cclement/cat/C2130m010
--------------------------------------------------------------------------------
Byte-by-byte Description of file: varphot.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- VName Variable star ID (V35 to V42)
5 A1 --- Filter [VR] Observation filter
7- 19 F13.5 d HJD Heliocentric Julian date at mid-exposure
21- 26 F6.3 mag magst ?=0.000 Standard magnitude
28- 33 F6.3 mag maginst Instrumental magnitude
35- 39 F5.3 mag e_maginst Magnitude uncertainty (standard or instrumental)
--------------------------------------------------------------------------------
Acknowledgements:
Daniel Bramich, dbramich(at)eso.org
(End) Daniel Bramich [ESO, Germany], Patricia Vannier [CDS] 22-Feb-2013