RR Lyrae stars in local group galaxies. II - NGC 147

Deep CCD images of NGC 147 taken with the '4-shooter' on the Hale 5 m telescope have been processed to find and photometrically measure RR Lyrae stars. 36 variable stars have been found, of which 32 are surmised to be RR Lyrae stars. Finding charts, periods, and light curves are presented....

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Bibliographic Details
Published in:The Astronomical journal 1990-07, Vol.100, p.108-126
Main Authors: Saha, A., Hoessel, John G., Mossman, Amy E.
Format: Article
Language:English
Subjects:
640102 > Astrophysics & Cosmology-- Stars & Quasi-Stellar, Radio & X-Ray Sources
Astrophysics
BRIGHTNESS
CHARGE-COUPLED DEVICES
CHEMICAL COMPOSITION
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
DETECTION
DISTANCE
GALAXIES
IDENTIFICATION SYSTEMS
MASS
OPTICAL PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
POPULATIONS
SEMICONDUCTOR DEVICES
STARS 640105 > Astrophysics & Cosmology-- Galaxies
VARIABLE STARS
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Summary:Deep CCD images of NGC 147 taken with the '4-shooter' on the Hale 5 m telescope have been processed to find and photometrically measure RR Lyrae stars. 36 variable stars have been found, of which 32 are surmised to be RR Lyrae stars. Finding charts, periods, and light curves are presented. The mean magnitude of the RR Lyraes is determined to be 25.25 mag. A distance modulus 23.92 is derived, based on the best currently available values of foreground extinction and mean absolute magnitudes of RR Lyrae stars. A wide range of periods is seen for the RR Lyrae stars, indicating a correspondingly wide range of metallicities for the stars in NGC 147. The distance modulus derived here places NGC 147 at a distance of 154 kpc from the center of M31, and in conjunction with the line sight velocities of these two galaxies, this implies a lower limit of 7.2 x 10 to the 11th solar masses for the mass of M31.
ISSN:0004-6256
1538-3881
DOI:10.1086/115495