A photometric study of the S0 galaxy NGC 3115.
Abstract
The two-dimensional surface brightness distribution in the SO galaxy NOC 3115 has been measured at U, V, and R by using a combination of photoelectric and photographic techniques. Particular attention has been paid to extending these observations to very low surface brightness values; at V our measurements reach v = 27.7 mag arcsec -2 The observed (U - V) and (V - R) color gradients show the same trends as reported in Strom et al.: the gradients are steepest along the minor axis of the galaxy. A more detailed study of the color distribution shows that contours of constant color (isochromes) are flatter than the isophotes in the inner region of the galaxy, while in the outer regions, the isochromes are less flattened relative to the isophotes. A distance modulus, (m - M) = 30.0 + 0.5 mag (10 Mpc), was derived for NOC 3115 by comparing the luminosity function of the globular cluster system surrounding this galaxy with that observed for M3 1. By combining the observed surface brightness profile with this distance estimate and an assumed MIL ratio, it is possible to estimate a mass MH for the halo component of NOC 3115. For an MIL = 10 at R, MH = 9.8 x 1010 M0. This value can be compared with a crude estimate of the disk mass MD < 3.6 x 1010 M0 derived from Williams's recently published rotation curve. Subject headings: galaxies: individual - galaxies: photometry - galaxies: stellar content - galaxies: structure
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1977
- DOI:
- 10.1086/155053
- Bibcode:
- 1977ApJ...212..335S
- Keywords:
-
- Astronomical Photometry;
- Galactic Evolution;
- Galactic Structure;
- Electrophotometry;
- Globular Clusters;
- Halos;
- Luminous Intensity;
- Star Distribution;
- Astronomy