Tagged Questions
1
vote
0answers
49 views
Why does $H_2$ form on such a long time scale?
If we were trying to figure out the time scale for a gas-phase reaction between two hydrogen atoms in a molecular cloud (which has density $~10^4/$cm$^3$), apparently the reaction would happen on a ...
0
votes
0answers
81 views
Mass loss rate of planetary nebulae
The “interacting wind” model of planetary nebulae is based on the idea that the white dwarf phase of stellar evolution is preceded by a red giant phase. A fast wind from the hot white dwarf overtakes ...
3
votes
1answer
530 views
Escape velocity of a rocket standing on Ganymede (Moon of Jupiter)
I want to calculate the escape velocity of a rocket, standing on the surface of Ganymede (moon of Jupiter) and trying to leave Ganymede.
My thinking was, the kinetic energy $E_{\text{KIN}}$ must be ...
3
votes
2answers
78 views
Balmer lines and their positions
I have two stars, both of which have Balmer lines at the same wavelength positions.
Why does this pattern exist?
3
votes
1answer
352 views
Hydrostatic equilibrium of a star - simplification math error
I am trying to do this question and getting stuck at interpreting what the question is asking for.
$$dP/dR = -g(R)\rho(R) = -[GM(<R)/R^2]\rho(R).$$
Thus when we descend a distance $\Delta R$ ...
