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Feb
10
comment Why do pre-main sequence stars show lithium in absorption?
Wouldn't the recombination radiation have some line emission as well, as the electron cascades down through the energy levels on its way to the ground state? Or in other words, isn't the $n=3$ level populated because of recombination (even if indirectly)?
Feb
10
comment Why do pre-main sequence stars show lithium in absorption?
I would expect the H$\alpha$ emission, in both cases, is from recombination, rather than line emission from a population of hydrogen somehow being held in an excited state. I just want to confirm that this is the case.
Sep
29
comment What is the brightest star (relative magnitude) in M31?
Yes, I am discounting supernovae. I am specifically wondering about stars Gaia could look at (so, ideally will be visible over a 5 year period).
Aug
20
comment What is the largest hydrogen-burning star?
Thanks for pointing that out. I updated the question to be core hydrogen burning.
Aug
20
comment What is the largest hydrogen-burning star?
I mean main sequence, I think.
May
29
comment Michigan's Pole Star
The time of day the Earth started to spin around Michigan would also be important.
May
11
comment Claim that 30-m class telescopes will have resolution far superior to Hubble: true?
Are there any indications that current or developing AO systems will actually allow these telescopes to work near the diffraction limit?
May
10
comment Why are Hubble images “Cut”
What purpose did the planetary camera chip serve relative to the three wide field chips? Why was it different?
Jan
28
comment Retrograde motion and Kuiper Belt Objects
A main component of my question is, given constraints like not being able to observe during the daytime, would we be able to see this prograde motion? If the prograde motion only ever occurs when the sun is up or close to up then we will never be able to observe it.
Jan
12
comment Meteorites bring water
You should include a reference to where you are getting "the latest information."
Dec
18
comment Is there anywhere I can find some kind of database on all known stars and their properties (mass, surface temperature, radius, and luminosity)?
Do you just want stars in our own galaxy or stars in other galaxies as well?
Nov
20
comment What scientific evidence is there to support or refute the Iron Sun Hypothesis?
Scientists thought something similar to what is proposed here in regards to the composition of the sun, until Cecilia Payne, in what has been called the "most brilliant PhD thesis ever written in astronomy" showed that the sun is made mostly of hydrogen.
Oct
24
comment How are stellar elemental abundances quoted?
So, not natural logarithm.
Oct
24
comment How are stellar elemental abundances quoted?
@Py-ser I already did in my original post of the question. To quote myself, "Close to the bottom of page 4 of this article (marked as page 164 in the upper left corner)"
Oct
23
comment How are stellar elemental abundances quoted?
@Py-ser, no the equations are not numbered. It's an inline equation to boot.
Oct
21
comment How do scientists know that a rock found on Earth came from Mars?
As a sidenote, if you go to the Smithsonian Museum of Natural History in Washington, D.C., you can actually touch a fragment of a meteorite believed to be from Mars.
Oct
21
comment How did the Mars satellites “take cover” from the recent comet flyby?
My question wasn't how to gauge whether the encounter with comet would affect instrument quality, but whether changing the orbit itself will affect the spacecrafts' ability to fulfil their primary missions in relation to Mars.
Jul
11
comment Sloan digital sky survey galaxies
This question may be more appropriate to ask the SDSS collaboration itself: helpdesk@sdss3.org
Jul
10
comment What is the difference between a dwarf spheroidal galaxy and a globular cluster?
This is incorrect. There are many so-called "satellite" galaxies that orbit the Milky Way without orbiting the Local Group's center. Check out this Wikipedia article for a list: en.wikipedia.org/wiki/List_of_Milky_Way%27s_satellite_galaxies
May
29
comment Recommendation for introductory cosmology text
Could this course be taken at my own pace?