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. =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_{sun}_ and M_V_=0.71 from nine RRab and [Fe/H]=-1.61, M=0.54M_{sun}_, Teff=7215K, logL=1.74L_{sun}_ and M_V_=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_{sun}_, 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