Tagged Questions
5
votes
2answers
64 views
How do interstellar hydrogen atoms form stars?
I would like to learn the basics about how interstellar matter contracts into stars under the influence of gravity.
Some of my questions:
Let's assume an ideal and infinite large cloud of equally ...
3
votes
1answer
143 views
How does a star ignite?
I remember reading that X-Rays are generated by 'braking' electrons in a Coolidge tube.
Is it fundamentally a matter that the extreme gravity immediately before a star ignites is so strong that it ...
0
votes
1answer
62 views
What would be the effect of an excess of up quarks on stellar formation?
Suppose you had 80% up quarks, and only 20% down quarks. How would this affect stellar formation?
0
votes
1answer
38 views
Conversion of a star
I need to know what would happen to a star that has size 2 times the solar mass. I guess it would either be a neutron or red giant. Is that right?
0
votes
1answer
40 views
Initial separation of neutron star/black hole binaries?
How would I go about finding the distribution of initial separations (i.e. the lengths between the centres of mass) of stars that make up binary systems. I am interested in neutron stars and stellar ...
3
votes
1answer
51 views
How accurate are our calculations about distant stars keeping in mind their enormous distances?
Since many stars are hundreds of light years away from the earth and therefore, what we observe of them today is really their distant past, how can we say anything with certainty about their ...
1
vote
2answers
152 views
Dark Matter 'Stars'
I'm aware that the Milky Way has a dark matter 'halo' around it, presumably a spherically symmetric distribution.
But I'm completely ignorant regarding the theories explaining dark matter... Is there ...
4
votes
2answers
81 views
What reason(s) exist to suppose that all degeneracy pressures can be overcome in Black-Hole formation?
In models of stellar collapse to a black hole, it is a given that density increases without bound towards a singularity. Electron degeneracy I get. Neutron degeneracy I get. I assume there's some ...
4
votes
4answers
260 views
Are galactic stars spiraling inwards?
Are the stars in our galaxy spiraling inwards towards the center, or are they in a permanent orbit?
And if we are heading towards the center then what is the rate of this process?
I started ...
1
vote
1answer
130 views
How to calculate gravity inside the star?
Gravity must decrease due to less effective mass when going inside the object but also must increase with depth inside the star due to its higher density. Is there a model or formula approximating ...
2
votes
1answer
46 views
Distinguishing Gamma-rays and stars from each other in nebulas
How do you tell the difference between a gamma-ray burst and a star just from a picture of a nebula, in which it cannot flash on and off here and there?
0
votes
1answer
57 views
Gravity and Magnetism on Stars
I am familiar with the fact that Magnetars have a really strong magnetic field and an ordinary star such as the Sun has a very strong gravitational field. But what about the opposite? What is the ...
3
votes
1answer
118 views
What are some ways that humans could have influence over what sequence a star was in?
How would a society go about either preventing our sun in its primary sequence from going into a Red Giant a billion years from now? Or perhaps, accelerating the process of going from main sequence ...
7
votes
3answers
485 views
Why doesn't helium start to fuse while there is still hydrogen fuel?
In all the descriptions of the stellar life cycle it seems as though helium doesn't start being fused until all (most?) of the hydrogen is gone.
Is this true? Why is this?
It seems counter ...
3
votes
1answer
145 views
Why can't a stable star have radius 1 < r < 9/8 its Schwarzschild radius?
From http://www.spacetimetravel.org/ssm/ssm.html :
A mass of 1.78 [in geometric units] corresponds to a ratio of radius to Schwarzschild radius of 9/8. Theory predicts that a smaller ratio is not ...
12
votes
1answer
89 views
Why don't stars in globular clusters all orbit in the same plane?
Globular clusters like Omega Centauri certainly don't seem to be very coplanar at all.
In other words, why doesn't the explanation at Why are our planets in the solar system all on the same ...
2
votes
2answers
19 views
What physical interactions actually make single stars leave their binary companions at formation?
From an interesting ScienceDaily article, I read this
Before the groups of stars disperse, binary stars move through their
birth sites and the group studied how they interact with other stars
...
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?
5
votes
1answer
125 views
How did enough material from other dying stars accumulate to start our sun and planets?
How far apart do scientists estimate was/were the dying star(s) that supplied the elements that comprise our sun, planet, and us? With stars so far apart and expansion of space (as I understand it) ...
4
votes
2answers
68 views
How can Y-dwarf stars have such a low temperature?
A recent article from NASA said they found some stars with temperatures "as cool as the human body." How is this possible? Does fusion still occur in these stars?
4
votes
2answers
95 views
Where does a star's angular momentum go as its spin slows down?
So we know that stars slow down as they age. But total angular momentum must be conserved. Where does that angular momentum go?
The dissipation of Earth's tides somehow transfers Earth's angular ...
13
votes
1answer
3k views
Is Jupiter a failed star?
In my physics lessons, my teachers have always been keen to tell my class that Jupiter is considered a 'failed star' by scientists. Is this true?
In my own effort I wondered if maybe this could just ...
3
votes
1answer
52 views
How are new nebulae being created?
The nebulae we see in the night sky are forming new stars.
The stars are eating up the nebulae and there is no obvious process in which those nebulae are being created to compensate for that.
...
9
votes
2answers
310 views
How can a Population III star be so massive?
How can a Population III star have a mass of several hundred solar masses? Normally the limit is about 100 solar masses.
7
votes
3answers
81 views
How would two equally massed stars orbit?
In an empty universe, except for two equally massed stars, how would they orbit? Or, for another example, if the earth suddenly grew to be the mass of the sun, how would they orbit, or interact? Would ...
