Basic parameters of dark halos in late-type spirals

Journal Article · Mon Jul 15 04:00:00 EDT 1985 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/163316· OSTI ID:5307652

Carignan, C; Freeman, K C

Mass models for three Sd galaxies in the Sculptor Group (NGC 7793, NGC 247, and NGC 300) and for the Sm galaxy NGC 3109 are presented. While a one-component disk model succeeds in fitting the observed rotation curve of NGC 7793, which extends only to 0.75R/sub 25/, an additional dark component is needed to explain the observed rotation curves of the three other galaxies which extend to 1.5--3.0R/sub 25/. We model this dark component with an isothermal sphere and attempt to estimate its core radius r/sub c/ and (one-component) velocity dispersion sigma. Although the rotation data extend to several disk scale lengths for these three galaxies, this is not far enough to define the ''turnover'' radius for the isothermal sphere: in the region where we have data, the contribution to the rotation curve from the isothermal sphere alone is not significantly different from solid body. Therefore, we can only give lower limits on r/sub c/ and sigma: these are in the range 10

• Research Organization: Mount Stromlo and Siding Spring Observatories and Kapteyn Laboratorium
• OSTI ID: 5307652
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 294:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCRETION DISKS
COSMIC RADIO SOURCES
DISTRIBUTION
GALACTIC EVOLUTION
GALAXIES
H1 REGIONS
LUMINOSITY
MASS DISTRIBUTION
MATHEMATICAL MODELS
MOTION
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
ROTATION
SPATIAL DISTRIBUTION