All Questions
212
questions
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2
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43
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Stars that have fairly high gravitational redshift and calculation of their surface temperature by Planck emition spectra?
How high can the ratio between gravitational redshift and planck emition spectra be depending on the mass of the star so by how much this gravitational redshift could elongate the Planck spectra of ...
- 2,255
2
votes
1
answer
38
views
Trajectory of supergiants on HR diagrams
I am a secondary school student currently studying cosmology. My A Level textbook supplies the following HR diagram with regards to what trajectories different stars follow:
I found myself unable to ...
1
vote
1
answer
57
views
Luminosity and absolute magnitude relationship
Context : an exercise gives the temperature, mass, distance and apparent magnitude of Sirius B and asks to calculate its density.
One key step of the calculation is to get the luminosity from the ...
1
vote
1
answer
36
views
Determining star position and velocity to deduce closest approach?
I am trying to replicate the results found for Gliese 710's closest approach of ~0.05 parsecs in 1.3 million years approximately. I thought that by plotting the sun at (0,0) and using the stars ra,dec,...
- 39
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votes
1
answer
44
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How is the trajectory of a star found relative to the Sun?
So i know we can get radial velocity by measuring blue shift and then we can use the distance to the star and its proper motion to get its tangential velocity. In the case of Bernards star, its ...
- 39
2
votes
2
answers
284
views
How to measure the ratio of a planet's radius to a star?
I was reading a physics problem related to astronomy, and upon re-reading it, I realized that it could be really indicated to extrapolate some really interesting physics-related information.
One of ...
- 439
0
votes
0
answers
17
views
Luminosity effect in stellar spectral classification
“Atoms with small ionization energy,Ir,will have a higher ionization in the atmospheres of giants than in those of dwarfs, and the atoms with large Ir will behave in the opposite way. This ...
- 327
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votes
1
answer
73
views
What's the nearest star that could go Supernova in the near future?
https://en.wikipedia.org/wiki/IK_Pegasi B is the nearest supernova candidate, but that white dwarf that's part of the system won't go supernova for around 2 billion years.
What's the nearest star that ...
- 2,908
0
votes
2
answers
92
views
Time of collapse of stellar dust cloud
A stellar gas cloud collapses onto itself once it reaches Jean's mass, and the time it takes for said cloud to collapse is given by: $t_{coll}=\sqrt{\frac{3\pi}{32G\rho_0}}$, where $\rho_0$ is the ...
- 1,616
0
votes
3
answers
90
views
How line of sight is determined?
How do they calculate the line of sight of a galaxy or binary star system from an observer's point of view. the velocity of a star in a binary star system depends on the line of sight so how do they ...
0
votes
0
answers
26
views
The role of gas pressure in the life cycle of stars
As a high school student, I am curious about the significance of gas pressure in the life cycle of a star. While I have read about the radiation pressure and the pressure caused by the energy released ...
- 647
2
votes
1
answer
1k
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Is the temperature of the hottest star's core known?
WR 102 is believed to be the hottest star in the observable universe, whose surface temperature is $210,000 ^\circ K$. But the related wikipedia entry does not say anything about the temperature of ...
user89243
1
vote
0
answers
22
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Stellar classification: Luminosity class
So in the astrophysics textbook by Carrol and Ostlie, when the luminosity class is discussed, it has such a sentence "The ratio of the strengths of two closely spaced lines is often employed to ...
- 161
14
votes
3
answers
3k
views
Is it possible to tell the difference between a young star that is just "big" and an older red giant?
I read the Wikipedia page for one of the biggest known stars, UY Scuti, and was curious to see the age of the star isn't really known at all.
When a star's hydrogen fuel is exhausted, it starts ...
- 243
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0
answers
67
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How is Starlight Reflected by Mirrors?
The chosen star is on the Z-axis of Mirror-A (Red). The Star image appears on the
face of this Mirror at the Origin of the CoSys.
Starlight Rays (Yellow lines) remain parallel, and do not diverge with ...
