A High Resolution Neutral Hydrogen Study of the Galaxy M 51,
Abstract
A 2 arc min synthesis study of the spiral galaxy M51 (NGC 5194) has been made in the lambda 21 cm emission line of neutral hydrogen. A morphological HI symmetry axis is found at a position angle of 22 degrees while the dynamically determined major axis is found at a position angle of -8 degrees. The velocities in the north-east outer spiral structure are found to be strongly non-circular. They agree in magnitude with predictions made by Toomre and Toomre for the tidal interaction between M51 and its companion galaxy NGC 5195. A possible continuation in neutral hydrogen of the outermost south-west spiral arm has been detected. M51 also exhibits a strong deficiency in HI surface density at its center. An upper limit of 10 billion solar mass units per beam area has been placed on the neutral hydrogen content of the companion galaxy NGC 5195. This, in turn, yields an upper limit of about 0.1 for the distance-independent ratio M(HI)/L(pg). (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1972
- Accession Number
- AD0754078
Entities
People
- L. Weliachew
- S. T. Gottesman
Organizations
- Owens Valley Radio Observatory