CDROM/APJ/V449/P164 Var. Stars in Mag. Cloud Clusters. II (Sebo & Wood 1995) ================================================================================ Variable Stars in Magellanic Cloud Clusters. II. NGC 1850 K. M. Sebo & P. R. Wood <1995, ApJ, 449, 164> =1995ApJ...449..164S ================================================================================ Abstract: We present the results of a study aimed at identifying variable stars in the rich LMC cluster NGC 1850. V and I band CCD imaging spanning more than 5 years in a 10' x 10' field surrounding the cluster has allowed us to identify more than 30 variable stars, including seven classical Cepheids, one anomalous Cepheid, two RR Lyrae variables, 19 long-period variables (LPVs), one blue eclipsing binary, one possible pair of eclipsing giants, and several peculiar variables. The only likely cluster member is a Cepheid. Isochrone fitting to the cluster CMD yields an age of 80 Myr if an LMC distance modulus of 18.5 is adopted. A comparison of pulsation and evolution masses for the Cepheids still yields a ratio of evolution to pulsation mass of ~1.2 for evolution models computed with core overshoot parameter Lambda = 0.5, where Lambda = 2d_ov/H_p, d_ov is the distance that convection overshoots beyond the Schwarzschild boundary and H_p is the pressure scale height. An overshoot parameter Lambda ~ 1.0 would be required to bring the evolution and pulsation masses into agreement. One of the Cepheids in the field is a bump Cepheid. A calculation of the bump mass yields a value in reasonable agreement with the pulsation mass. We show that detailed modelling of individual bump Cepheids is capable of providing very tight constraints on the LMC distance modulus. The Cepheid period-luminosity-color relation compared to the theoretical relation yields a LMC distance modulus of 18.60. Finally, arguments are presented which suggest that the LPVs are a mixture of fundamental mode pulsators and small-amplitude overtone pulsators. Keywords: Cepheids -- Magellanic Clouds -- open clusters and associations: individual (NGC 1850) -- stars: evolution Description: These files are the calibrated raw photometric data. Each file contains the photometry for one variable. In the case where there are differing numbers of data points in each color, the color with the fewer data points has been padded with zeros. File Summary: -------------------------------------------------------------------------------- File Name Lrecl Records Explanations -------------------------------------------------------------------------------- 9.dat 45 59 Variable star 9 photometry 17.dat 45 83 Variable star 17 photometry 39.dat 45 51 Variable star 39 photometry 58.dat 45 79 Variable star 58 photometry 110.dat 45 51 Variable star 110 photometry 120.dat 45 43 Variable star 120 photometry 269.dat 45 64 Variable star 269 photometry 341.dat 45 26 Variable star 341 photometry 347.dat 45 24 Variable star 347 photometry 349.dat 45 39 Variable star 349 photometry 395.dat 45 66 Variable star 395 photometry 441.dat 45 38 Variable star 441 photometry 502.dat 45 25 Variable star 502 photometry 504.dat 45 40 Variable star 504 photometry 558.dat 45 35 Variable star 558 photometry 574.dat 45 42 Variable star 574 photometry 587.dat 45 57 Variable star 587 photometry 652.dat 45 84 Variable star 652 photometry 670.dat 45 80 Variable star 670 photometry 679.dat 45 40 Variable star 679 photometry 1038.dat 45 42 Variable star 1038 photometry 1078.dat 45 30 Variable star 1078 photometry 1084.dat 45 26 Variable star 1084 photometry 1135.dat 45 25 Variable star 1135 photometry 1847.dat 45 78 Variable star 1847 photometry 1906.dat 45 74 Variable star 1906 photometry 1956.dat 45 34 Variable star 1956 photometry 2093.dat 45 49 Variable star 2093 photometry 2199.dat 45 32 Variable star 2199 photometry 2202.dat 45 40 Variable star 2202 photometry 2268.dat 45 37 Variable star 2268 photometry 7254.dat 45 64 Variable star 7254 photometry 9276.dat 45 12 Variable star 9276 photometry 10753.dat 45 49 Variable star 10753 photometry -------------------------------------------------------------------------------- Byte-by-byte Description of file: 9.dat 17.dat 39.dat 58.dat 110.dat 120.dat 269.dat 341.dat 347.dat 349.dat 395.dat 441.dat 502.dat 504.dat 558.dat 574.dat 587.dat 652.dat 670.dat 679.dat 1038.dat 1078.dat 1084.dat 1135.dat 1847.dat 1906.dat 1956.dat 2093.dat 2199.dat 2202.dat 2268.dat 7254.dat 9276.dat 10753.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 F8.3 --- JD_V []?=0000.000 Julian date of V observation 9-15 F7.3 mag V []?=00.000 V magnitude 16-21 F6.3 mag e_V []?=0.000 V magnitude error 22-24 3X --- --- Blank 25-32 F8.3 --- JD_I []?=0000.000 Julian date of I observation 33-39 F7.3 mag I []?=00.000 I magnitude 40-45 F6.3 mag e_I []?=0.000 I magnitude error -------------------------------------------------------------------------------- ================================================================================ (End) Lee Brotzman [ADS] 10-Oct-95