Density and Mass Distribution of Spiral Galaxy NGC 3198

Abstract

The density and mass of the spiral galaxy NGC 3198 have been studied as functions of the distance from the center of galaxy depending on its observed rotation curve. Calculation of density and mass at different radii of the galaxy NGC 3198 show that the central inner density ρ1(r) at r < r t (r t is the turn-off radius) is found to be constant ρ1 = 0.387 M o pc−3, while the density ρ2(r) of the outer region r > r t is much less than the inner region, which varies from 0.0187 M o pc−3 at r = 4 kpc to 0.00278 M o pc−3 at r = 30 kpc. On the other hand, the inner mass m1(r) at r < r t grows from 1.33 × 109 M o at r = 0.1 kpc to a mass of 8.539 × 109 M o at r = 4 kpc, while the outer mass m2(r) at r ≥ r t changes from 8.539 × 109 M o at the turn-off radius r t to 5.262 × 1010 M o at r = 30 kpc of the galaxy. Finally, the behavior of the calculated density and mass is consistent with other works.

A new approach to dark matter from the mass-radius diagram of the Universe

“…The mass density distribution of this galaxy should be approximately constant below 5 kpc and then declining, reducing by about an order of magnitude at 30 kpc. The estimated visible mass of this galaxy is about 10 10 M , while the total mass at 30 kpc is M ∼ 5 ÷ 11 × 10 10 M , see for instance [68] [62,63,64], see also [65]. The red curve represents the visible contribution, obtained with Eq.…”