The Velocity Field in M51.

Abstract

view Abstract Citations (66) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Velocity Field in M51. Burbidge, E. Margaret ; Burbidge, G. R. Abstract The prime-focus spectrograph on the Lick 120-inch telescope and the Babcock spectrograph at the prime focus of the McDonald 82-inch telescope have been used to make a detailed study of the motions of the ionized gas in MS 1. Observations of a number of emission patches in the spiral arms have been made to determine the form of the rotation-curve, and it has been concluded that the position angle of the line of nodes is 0 with an uncertainty of about 10 . From the rotation-curve we have determined that the mass of M51 within 5.5 kpc of the center is <6 X 1010 Me, where a distance of 4 Mpc has been taken. A large number of spectra have been obtaine through the nuclear region (in general within about 30" or 600 pc from the center) in fifteen position angles. By projecting the rotation-curve into the various position angles and comparing the curves with the observed velocities, large-scale departures from circular motion have been found. These have magnitudes <100 km/sec in the line of sight and are of both signs. The velocity field is highly asymmetrical with maximum departures from circular motion between 51.5 and 81.5 in both the NE. and SW. quadrants. Departures are also seen in position angles 24 and 141.5 . A discussion is given of the various types of non-circular motions which are compatible with the observations, or can be ruled out by them. Finally, a spectrum of NGC 5195 is described. It is concluded that this galaxy is a dwarf 80 system and not an irregular galaxy similar to NGC 3077 and M82 as has been previously proposed. Publication: The Astrophysical Journal Pub Date: November 1964 DOI: 10.1086/148049 Bibcode: 1964ApJ...140.1445B full text sources ADS | data products NED (3) SIMBAD (1)