6,367 reputation
21956
bio website astro.uvic.ca/~koman
location Canada
age 25
visits member for 2 years, 4 months
seen Dec 22 at 4:07

I am an astrophysics graduate student.


Dec
3
revised Do celestial objects experience drag from the near vacuum of space/does the near vacuum have a mean velocity?
added 1810 characters in body
Dec
3
comment Do celestial objects experience drag from the near vacuum of space/does the near vacuum have a mean velocity?
A bit of a long interval, but the answer is pretty easy I guess, so I can do a quick edit. If you want a lot more detail (there's always more detail to add in astronomy...), perhaps a new question?
Dec
1
comment How much of a galaxy's mass is in stars?
@AbanobEbrahim sorry I was sloppy - I should have said stellar mass rather than number of stars.
Nov
30
comment How much of a galaxy's mass is in stars?
@AbanobEbrahim Stellar mass is just the stars - no gas and dust. 10 billion is a little bit high for number of stars, but not by much, and as I said the $1 {\rm M}_\odot/{\rm L}_\odot$ is just a rough idea, it can vary by quite a bit.
Nov
29
comment How much of a galaxy's mass is in stars?
See this paper for instance: adsabs.harvard.edu//abs/2001ApJ...550..212B The stellar M/L ratio has quite a bit of scatter, but it's more or less centered (on log scale) around $\log_{10}M_*/L\sim0.0$. So within an order of magnitude or so, $M_*/L=1$ is correct.
Nov
29
comment How much of a galaxy's mass is in stars?
@AbanobEbrahim note that what I stated was a rough STELLAR mass-to-light ratio, which is of course quite different from a TOTAL mass-to-light ratio.
Nov
28
comment How much of a galaxy's mass is in stars?
@KyleKanos certainly related, but hardly a duplicate - this seems to be asking more how to measure the stellar mass of a given galaxy than anything about the global baryon fraction, or stellar mass fraction.
Nov
28
answered How much of a galaxy's mass is in stars?
Nov
21
comment Has the number of new stars born decreased over time? And why?
@DavidLynch no need to replace Universe by Galaxy - we have a pretty good handle on the cosmic mean star formation rate as a function of redshift, at least back to moderate redshifts (~2-3).
Nov
20
reviewed Leave Closed What are fundamental dimensions used to describe the physical universe?
Nov
20
reviewed Approve Energy of a signal
Nov
20
reviewed Approve What is the movement of the material point?
Nov
20
reviewed Close What is the movement of the material point?
Nov
20
reviewed Close Why human and most of vertebrates cannot see Near-Infrared light (720nm-1500nm)?
Nov
20
reviewed Close What (if any) state did energy exist in prior to the big bang?
Nov
19
reviewed Approve Does infrared light pass through active shutter glass?
Nov
17
comment How is spectrum controlled?
I'm not sure what you mean by spectrum, but it doesn't seem to be what most people mean when they use that word... Do you perhaps mean in the sense of radio frequencies?
Nov
6
comment What would the collision between a (large) solid planet and a gas giant be like?
No time to write an answer right now, but some of the details will depend on the impact speed - for instance if the impactor is coming in fast enough to be supersonic in the gas giant's atmosphere, you're going to end up with a lot of gas with nowhere to go in a timely manner. Depending on the gas column mass along the direction of impact, you could temporarily punch a hole through the gas giant. At lower speeds, the gas will behave more like a normal fluid, think rock dropping into a (gas) pond.
Nov
6
reviewed Leave Closed Calculating the acceleration in a multiple pulley system with one mass?
Nov
6
reviewed Reopen Can the angular momentum of any rigid body (symmetrical or asymmetrical) be found this way?