Questions related to the evolution of stars.
Questions tagged [stellar-evolution]
229 questions
11
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1 answer
What is the reason for high lithium concentrations in Sun-like stars?
In reading the European Space Organisation paper Lithium depletion in solar-like stars: no planet connection (Baumann et al. 2010), several conclusions based on their observations include:
Lithium depletion in Sun-like stars is independent of…
user2449
9
votes
1 answer
Order of shells formed in a massive star
In addition to the question with the picture here, why do shells don't form the same order as the alpha process?
image credit: Gemini Observatory/NSF/C.Aspin
Jack the Ranger
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8
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2 answers
Temporal path through Hertzsprung-Russell diagram?
Is there graphic of typical temporal paths that stars take through the Hertzsprung-Russell diagram?
oasis
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7
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2 answers
Is there an element of chance/chaos in stellar evolution?
Since stars are an ideal example of macroscopic objects, is their evolution determined by their initial mass and metallicity?
Are there any non-trivial random internal processes going on that may significantly affect a star's development and…
Deer Hunter
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5
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2 answers
Do large stars ignite then continue to increase in size, or do they ignite only once they grow larger?
My limited understanding of stellar formation is that a gas cloud condenses enough that various forces (just gravity?) eventually lead to enough pressure to ignite nuclear fusion. However, since stars vary vastly in size it got me thinking: Do…
Michael Stachowsky
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4
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stellar evolution fortran code-runge kutta mass step from center to fitting point
I am trying to integrate the four stellar model equations from the core to a fitting point and from the surface to the fitting point ($x_f$). When I start the outward integration, however, I have to use a huge mass shell step $dx$ where $x_1=dx$ too…
tzakara
- 41
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4
votes
2 answers
Trying to understand this graph (stellar activity)
I managed to trace this graph back to http://katjapoppenhaeger.com/?p=457. It's meant to show how stellar activity declines with time for different star types, and whilst I get the general idea, I don't really understand what either axis means. Y…
Kazon
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4
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1 answer
Why do proto stars on the Hayashi track get dimmer as they contract?
Why do proto stars on the Hayashi track get dimmer as they contract?
My expectation is that they would get hotter and brighter the more they contact. Why is this wrong?
user10250
3
votes
0 answers
What estimate can be made of the time before a change in the Sun's intensity would make the earth uninhabitable?
From observation of stars we know that there are many types of stars that evolve over time and change and this known as stellar evolution. Over time a star changes in its size and in the intensity of its radiation.
Based on our observation of other…
Tyler Durden
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3
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Are red clump stars horizontal branch stars?
The wikipedia article about horizontal branch stars says:
A related class of stars is the clump giants, those belonging to the
so-called red clump, which are the relatively younger (and hence more
massive) and usually more metal-rich population I…
zabop
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3
votes
1 answer
Will the Sun cool only after it left main sequence?
I thought that the answer is yes, a little bit. As the sun runs out of hydrogen, then it it gets more and more contracted, increasing pressure, temperature, and therefore luminosity. This is supported by this answer saying, about main sequence…
zabop
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3
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0 answers
How much do stars brighten as they age?
There's a fair amount of info out there about the mass-luminosity relation, i.e. giving some approximate equations for the luminosity of a main sequence star as a function of its mass, e.g. $L_* = M_*^4$ (relative to the Sun's mass and luminosity,…
Matt Dickau
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3
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1 answer
Why do PMS stars on the Hayashi track remain at a constant temperature while they contract?
Why do pre-main-sequence stars on the Hayashi track remain at a constant temperature while they contract?
I've read the Wikipedia article, so no need to repeat the derivation.
What I took away from that is that the extra heat generated by…
user10250
2
votes
2 answers
Rate of star collpse
It is believed that our sun will become a red giant with a diameter of about 1 AU. When the fusion slows down, gravity will collapse the sun. Since the energy release from the fusion diminishes slowly (maybe hundreds of years for a significant…
LDC3
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2
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1 answer
Why do heavy mid-sized stars become more luminous as they leave the subgiant branch entering the red-giant branch?
Wikipedia says:
For stars heavier than the around a solar mass the "outer layers cool sufficiently to become opaque" which "cause the hydrogen shell to increase in temperature and the luminosity of the star to increase, at which point the star…
zabop
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