Mass of the Galaxy Inferred from Outer Rotation Curve
Abstract
Using an outer rotation curve of the Galaxy, we explore the galactic constants Theta_ {0} and R0 and the mass of the Galaxy. We show that Theta_ {0} of 200 km s(-1) is more favorable than the IAU standard value of 220 km s(-1) , and also show that if Theta_ {0} is smaller than 207 km s(-1) the rotation curve beyond 2R0 is declining in Keplerian fashion. In the case of Theta_ {0}=200 km s(-1) and R0= 7.6 kpc, the total mass and the extent of the Galaxy inferred from the rotation curve are 2.0+/-0.3*E(11) MO and 15 kpc, respectively. These results may significantly change the previous view of the Galaxy, that its outer region is dominated by a massive dark halo extending out to several tens of kpc.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- December 1996
- DOI:
- 10.1093/pasj/48.6.L103
- arXiv:
- arXiv:astro-ph/9611156
- Bibcode:
- 1996PASJ...48L.103H
- Keywords:
-
- DARK MATTER;
- GALAXIES: MILKY WAY;
- ROTATION;
- Astrophysics
- E-Print:
- Latex, 4 pages and 3 figures, to appear in PASJ Letter Vol.48 No.6