M75, a Globular Cluster with a Trimodal Horizontal Branch. Ii. Bv Photometry of the Rr Lyrae Variables

نویسنده

  • T. M. CORWIN
چکیده

We present new BV CCD photometry, light curves, and ephemerides for 9 previously known, 29 newly detected RR Lyrae variables and one newly detected variable of an unknown type in the globular cluster M75. The photometry used for the detection of the additional variables was obtained with the image subtraction package ISIS. The data were acquired on an observing run in July 1999 and range over 7 observing nights. Estimates of fundamental photometric parameters are presented including intensityand magnitude-averaged B and V magnitudes, magnitude-averaged colors, pulsation periods, and pulsation amplitudes. The mean period of the RRab variables, 〈Pab〉 = 0.5868 d, and the number fraction of RRc stars, Nc/NRR = 0.342, are both large for an Oosterhoff type I (OoI) globular cluster, suggesting that M75 may be Oosterhoff-intermediate. Possible conflicts between Oosterhoff-type determination based on the AV − log P and AB − log P diagrams are discussed. The physical parameters of the RRc and RRab variables, as obtained from Fourier decomposition of their light curves, do not show any clear deviation from normal OoI behavior. Subject headings: Galaxy: globular clusters: individual: M75 (NGC 6864) – Stars: horizontal-branch – Stars: variables: RR Lyr

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

M75, a Globular Cluster with a Trimodal Horizontal Branch. I. Color-magnitude Diagram

Deep UBVI photometry for a large field covering the distant globular cluster M75 (NGC 6864) is presented. We confirm a previous suggestion (Catelan et al. 1998a) that M75 possesses a bimodal horizontal branch (HB) bearing striking resemblance to the well-known case of NGC 1851. In addition, we detect a third, smaller grouping of stars on the M75 blue tail, separated from the bulk of the blue HB...

متن کامل

Variable Stars in the Unusual , Metal - Rich Globular Cluster NGC 6441

We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6441 using time-series BV photometry. The total number of variables found near NGC 6441 has been increased to ∼ 104, with 48 new variables being found in this survey. A significant number of the variables are RR Lyrae stars (∼ 46), most of which are probable cluster members. As was noted by Layden et al. (1999...

متن کامل

ar X iv : a st ro - p h / 03 04 07 7 v 1 3 A pr 2 00 3 Variable Stars in Metal - Rich Globular Clusters . II . NGC 6316 Andrew

We present time-series V I photometry of the metal-rich globular cluster NGC 6316. Our color-magnitude diagrams show a predominantly red-clump horizontal branch morphology with no evidence of the blue extensions seen in NGC 6388 and NGC 6441. Our data are in good agreement with published estimates of the reddening and metallicity provided the cluster has an absolute distance modulus of 15.50 ma...

متن کامل

CCD Photometry of the Globlular Cluster NGC5986 and its Post-Asymptotic-Giant-Branch and RR Lyrae Stars

We have obtained new CCD BV photometry of the little-studied southern Galactic globular cluster NGC5986, including light curves of 5 of its RR Lyrae variables. The cluster’s red giant branch bump is detected for the first time at V = 16.47 ± 0.03. We derive a reddening and true distance modulus of E(B − V ) = 0.29 ± 0.02 and (m−M)0 = 15.15 ± 0.10, respectively. The cluster’s color-magnitude dia...

متن کامل

Lyrae variables in Galactic globular clusters IV . Synthetic HB and RR

We present theoretical predictions concerning horizontal branch stars in globular clusters, including RR Lyrae variables, as derived from synthetic procedures collating evolutionary and pulsational constraints. On this basis, we explore the predicted behavior of the pulsators as a function of the horizontal branch morphology and over the metallicity range Z=0.0001 to 0.006, revealing an encoura...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2003