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J/ApJ/449/164        Variable Stars in MC Clusters. II            (Sebo+ 1995)

Variable Stars in Magellanic Cloud Clusters. II. NGC 1850 Sebo P.R., Wood K.M. <Astrophys. J. 449, 164 (1995)> =1995ApJ...449..164S
ADC_Keywords: Magellanic Clouds ; Stars, variable ; Clusters, open ; Photometry, CCD Keywords: Cepheids - Magellanic Clouds - open clusters and associations: individual (NGC 1850) - stars: evolution 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'x10' 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 = 2dov/Hp, 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. Description: 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. Objects: ---------------------------------------------------- RA (2000) DE Name in SIMBAD ---------------------------------------------------- 05 08 18.4 -68 46 46 Cl* NGC 1850 SW 9 05 08 44.1 -68 45 28 Cl* NGC 1850 SW 17 05 08 28.2 -68 48 24 Cl* NGC 1850 SW 39 05 08 43.6 -68 45 33 Cl* NGC 1850 SW 58 05 09 16.0 -68 44 30 Cl* NGC 1850 SW 110 05 09 24.3 -68 47 24 Cl* NGC 1850 SW 120 05 08 54.9 -68 43 10 Cl* NGC 1850 SW 269 05 08 07.3 -68 41 09 Cl* NGC 1850 SW 341 05 08 12.9 -68 41 03 Cl* NGC 1850 SW 347 05 08 16.4 -68 48 38 Cl* NGC 1850 SW 349 05 08 39.6 -68 43 46 Cl* NGC 1850 SW 395 05 09 08.8 -68 48 53 Cl* NGC 1850 SW 441 05 09 35.8 -68 41 43 Cl* NGC 1850 SW 502 05 09 38.4 -68 48 07 Cl* NGC 1850 SW 504 05 08 05.0 -68 42 12 Cl* NGC 1850 SW 558 05 08 09.4 -68 43 22 Cl* NGC 1850 SW 574 05 08 14.5 -68 44 55 Cl* NGC 1850 SW 587 05 08 28.3 -68 45 04 Cl* NGC 1850 SW 652 05 08 32.5 -68 44 30 Cl* NGC 1850 SW 670 05 08 35.4 -68 48 59 Cl* NGC 1850 SW 679 05 09 28.3 -68 47 51 Cl* NGC 1850 SW 1038 05 09 41.6 -68 45 26 Cl* NGC 1850 SW 1078 05 09 42.5 -68 45 16 Cl* NGC 1850 SW 1084 05 08 14.3 -68 49 42 Cl* NGC 1850 SW 1135 05 09 00.5 -68 47 02 Cl* NGC 1850 SW 1847 05 09 05.6 -68 46 30 Cl* NGC 1850 SW 1906 05 09 10.1 -68 41 38 Cl* NGC 1850 SW 1956 05 09 20.5 -68 45 54 Cl* NGC 1850 SW 2093 05 09 31.8 -68 48 52 Cl* NGC 1850 SW 2199 05 09 30.5 -68 42 27 Cl* NGC 1850 SW 2202 05 09 39.7 -68 45 35 Cl* NGC 1850 SW 2268 05 08 58.4 -68 47 18 Cl* NGC 1850 SW 7254 05 09 47.9 -68 45 08 Cl* NGC 1850 SW 9276 05 08 19.6 -68 44 44 Cl* NGC 1850 SW 10753 ------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file idata 30 1575 I photometry vdata 30 1537 V photometry
Byte-by-byte Description of file: vdata
Bytes Format Units Label Explanations
1- 5 I5 --- Star Number of star 7- 17 F11.3 d JD Julian date of V observation 19- 24 F6.3 mag Vmag V magnitude 26- 30 F5.3 mag e_Vmag V magnitude error
Byte-by-byte Description of file: idata
Bytes Format Units Label Explanations
1- 5 I5 --- Star Number of star 7- 17 F11.3 d JD Julian date of I observation 19- 24 F6.3 mag Imag I magnitude 26- 30 F5.3 mag e_Imag I magnitude error
Origin: AAS CD-ROM series, Volume 5, 1995 Lee Brotzman [ADS] 10-Oct-95 Historical Notes: The original 34 files were merged into two files at CDS.
(End) [CDS] 29-Jan-1996
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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