The distribution and kinematics of neutral gas in M31

Journal Article · Wed May 01 04:00:00 EDT 1991 · Astrophysical Journal; (United States)

DOI:https://doi.org/10.1086/169954· OSTI ID:5393195

Braun, R ^[1]

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1. Netherlands Foundation for Research in Astronomy, Dwingeloo (Netherlands) National Radio Astronomy Observatory, Socorro, NM (USA)

The kinematic signature of individual spiral arm segments are used here to make a very compact yet quite complete parameterization of the global neutral hydrogen content of M31. Two continuous, trailing spiral arms can be traced from about 0.5 to 27 kpc from the nucleus which accurately account for the kinematic and spatial distribution of gas. The three-dimensional geometry of the gas distribution is derived with only limited assumptions concerning axisymmetry of the velocity field. Significant variations in inclination as a function of azimuth and radius are found, leading to departures of the local midplane from a few hundred pc in a tilted disk in the inner galaxy to in excess of a kpc in the 'warp' of the outer galaxy. The distribution of exponential scale height of the gas with radius varies between 200 and 600 pc, and the spiral pattern in the inner galaxy has an elliptical distortion which leads to significant corrections to the axisymmetric rotation velocity and implied mass distribution. 48 refs.

• OSTI ID: 5393195
• Journal Information: Astrophysical Journal; (United States), Journal Name: Astrophysical Journal; (United States) Vol. 372; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CONFIGURATION
COSMIC GASES
COSMIC RADIO SOURCES
DISTRIBUTION
FLUID MECHANICS
FLUIDS
GALAXIES
GASES
H1 REGIONS
INTERSTELLAR SPACE
MASS DISTRIBUTION
MECHANICS
MORPHOLOGY
PARTICLE KINEMATICS
SPACE
SPATIAL DISTRIBUTION
SPIRAL CONFIGURATION