Extended rotation curves of high-luminosity spiral galaxies. II - The anemic SA galaxy NGC 4378

Abstract

view Abstract Citations (34) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Extended rotation curves of high-luminosity spiral galaxies. II. The anemic Sa galaxy NGC 4378. Rubin, V. C. ; Ford, W. K., Jr. ; Strom, K. M. ; Strom, S. E. ; Romanishin, W. Abstract Spectroscopic and photometric observations are reported for the Sa galaxy NGC 4378. Our data suggest that this galaxy is located at a distance of 50 Mpc; if so, its absolute blue luminosity MB = -21.1. From an analysis of its rotation curve, a total mass, = 3.6 + 0.5 x 10" , is derived. The mass to blue-luminosity ratio increases from /LB = 4.0 for regions within 2 kpc of the nucleus to /LB 10 in the outer regions of the galaxy. The hydrogen-mass to blue- luminosity ratio, HI/LB 0.1, is quite typical of early-type galaxies. Star formation in NGC 4378 follows a pattern qualitatively similar to that in our own Galaxy. Newly formed stars are virtually absent in the nuclear bulge region but increase in relative number out to a radius of 18 kpc, beyond which the star-formation rate drops. Ionized hydrogen regions in NGC 4378 show a ratio [N ii]/Ha which drops below unity only beyond 10 kpc. This result suggests that metal enrichment in the disk of this galaxy may have proceeded to a greater degree and over a larger fraction of the disk than is typical of other early-type galaxies. NGC 4378 has been called an "anemic" spiral by van den Bergh. This classification appears to result from the combined influences of a somewhat fainter than normal disk surface brightness and a lower star-forming efficiency in its arms. Subject headings: galaxies: individual - galaxies: internal motions - galaxies: photometry - galaxies: stellar content - galaxies: structure Publication: The Astrophysical Journal Pub Date: September 1978 DOI: 10.1086/156426 Bibcode: 1978ApJ...224..782R Keywords: Astronomical Photometry; Astronomical Spectroscopy; Galactic Rotation; Galactic Structure; Spiral Galaxies; Astrometry; Brightness; Emission Spectra; Galactic Evolution; Hydrogen; Mass Distribution; Mass Ratios; Stellar Evolution; Ubv Spectra; Astronomy; Photometry:Spiral Galaxies; Spiral Galaxies:Internal Motions; Spiral Galaxies: Structure full text sources ADS | data products NED (2) Related Materials (4) Part 1: 1977ApJ...217L...1R Part 3: 1978ApJ...226..770P Part 4: 1978ApJ...225L.107R Part 5: 1979ApJ...230...35R