CCD photometry of the globular cluster M2: RR Lyrae physical parameters and new variables

Lázaro, C.; Arellano Ferro, A.; Arévalo, M. J.; Bramich, D. M.; Giridhar, S.; Poretti, E.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 372, Issue 1, pp. 69-80.

Advertised on:
10
2006
Number of authors
6
IAC number of authors
2
Citations
24
Refereed citations
23
Description
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 = 1.63Lsolar and MV = 0.71 from nine RRab and [Fe/H] = -1.61, M = 0.54Msolar, Teff = 7215K, logL = 1.74Lsolar 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/Lsolar, 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.
Type