\magnification=\magstep2 

$$
F  \quad = \quad {{G M_\odot m}\over{r^2}} \quad = \quad { {m v^2}\over{r}} 
$$

$$
v \quad = \quad \sqrt {\left( {{G M_\odot} \over {r}} \right) } 
$$


$$
F  \quad = \quad {{G M_{\rm int} \thinspace m}\over{r^2}} \quad = \quad { {m v^2}\over{r}} 
$$

$$
v(r) \quad = \quad \sqrt {\left( {{G M_{\rm int}} \over {r}} \right) } 
$$

$$
{ { M_{\rm int}} \over {r}} \quad = \quad {\rm Const}
$$

$$
{\rm G2V \qquad} { {M} \over {L} } \quad = 
        \quad {{ 1 \thinspace M_\odot} \over {1 \thinspace  L_\odot}} \quad             = \quad 1
$$

$$
{\rm B3V \qquad} { {M} \over {L} } \quad = 
        \quad {{ 10 \thinspace M_\odot} \over {5000 \thinspace  L_\odot}} \quad             = \quad 0.002
$$

$$
{\rm M2V \qquad} { {M} \over {L} } \quad = 
        \quad {{ 0.4 \thinspace M_\odot} \over {0.032 \thinspace  L_\odot}} \quad             = \quad 12.5
$$



$$
{\Omega_B} h^2 \quad \simeq \quad 0.02 
$$

$$
{\Omega_M} \quad \simeq \quad 0.27 
$$



\bye
