Questions tagged [stellar-evolution]
The stellar-evolution tag has no usage guidance.
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How fast is the naked-eye visible transition of a main sequence star to a giant?
I know the evolution of a main sequence star to a giant is a process that takes millions and millions of years, but how fast is the VISIBLE change? Basically, will our sun, for example, slowly grow to ...
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Why are black holes sometimes formed without supernovae?
I've heard that very massive stars can sometimes collapse into black holes without creating supernovae.
How does this happen?
(I suspect it's something to do with the relative lack of Urca process ...
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Difference between star formation rate and star formation history
When we speak about galaxies evolution, what is the difference between the star formation rate and the star formation history?
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Dynamical instability and thermal instability
I'm studying instability in Stellar Dynamics (in particular globular clusters instabilities).
I have not understood clearly the definition of these concept.
Dynamical instability is the study of the ...
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How many type II supernovae are there per stellar mass formed?
I have been searching for the number of type II (core-collapse) supernovae per unit of stellar mass formed.
It is my understanding that a star must have an initial mass of at least 8 times and no more ...
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Would a black hole instantly form when a neutron star slips below the phantom event horizon?
So lets say we have a neutron star that is just few inches away from the phantom horizon and only needs 500 kg before collapsing. So lets say hypothetically that a ship that is designed to survive the ...
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Why don't less massive stars explode in form of supernovas?
I'm a high school student with a question about supernovas and the life cycle of stars. I understand that supernovas occur in massive stars when they run out of fuel and collapse, resulting in a ...
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Can a massive star become a red giant more than once?
Massive stars may undergo multiple fusion processes as they near the end of their lifespans. Our sun will eventually start fusing helium in its inner core so that carbon is formed. As this occurs, the ...
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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 ...
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Pair-instability supernovae: how does it happen?
How does the formation of electron positron pairs increase the energy density and softens the EOS?
I trrying to understand the pair instability supernova. In many texts and articles, it is written ...
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Why is the common envelope ejected in some accretor-donor systems?
As an example, let us consider a binary system of a neutron star and an evolved star (e.g. red giant) that has expanded, filled its roche lobe, and started the mass transfer onto the neutron star.
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How hot is the core of a star just before it collapses to form a black hole?
Is the core of a star still hot as the star collapses under its own gravity?
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Stellar structure and evolution book [duplicate]
I am studying stellar structure and evolution. I have read many books about this but I have not finished any of them. Textbook like Dina Prialnik, Paul, Kippenhan, Stellar Interior by Carl J. Hansen ...
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How could have Boson Stars formed in the universe at all?
Boson particles have been predicted by some to have been able to form stars known as Boson Stars. I am curious as to how these stars could have formed given that Boson particles are not truly affected ...
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How long does the expansion last?
It is known that when a main sequence star consumes about 10% of the central hydrogen, the external envelope starts to expand leading the star to the phase of a red giant.
How long does this expansion ...
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Why do elliptical galaxies not have large proportion of blue stars?
In an article it was given that elliptical galaxies are also formed when a spiral galaxy experiences continuous star burst thus depleting it's gas. So if this is correct than why do elliptical ...
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Does a star that is far from any galaxy tend to rotate slower?
I'm wondering whether the rotation of a galaxy and the buffeting of the gas and dust within it by light and stellar wind and pressure waves makes nebulae or gas clouds in galaxies have more angular ...
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Do stars lose spin angular momentum, to planets, radiation, or gravitational waves, or in some other way get a longer period?
A spinning star is throwing off stellar wind, and electromagnetic radiation, which might be carrying away angular momentum, so that the star loses angular momentum, and its angular momentum per unit ...
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Evolution into a main sequence star
I was reading the following from the textbook An Introduction to Modern Astrophysics by
Bradley W. Carroll Dale A. Ostlie,
"Due to the onset of the highly temperature-dependent CNO reactions, a ...
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How can we be sure that degenerate stellar matter does not bring up emergent phenomena not considered during their theoretical analysis?
With the astrophysical predictions on stellar evolution (which I admit I am not familiar with in detail) I always ask myself how we can be sure that they are correct although they are extremely ...
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Inner and outer orbital limit of planets in single-star systems
I am trying to find a rough cut-off of the inner and outer orbits of native planets around a single star. I know about the Roche limit and Hill Sphere, but these are not the limits I am looking for. I ...
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Energy released from forming a black hole?
Gravitational collapse release potential energy, in some cases a huge amount of it. In the case of a black hole, that collapse goes to "infinity" which suggests the release of "infinite&...
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A question regarding water and a possible proton-proton chain reaction
I believe it is the case that stars as low as about 0.08 solar masses undergo the proton-proton chain reaction. So if you were to have a gas of more than about that mass of hydrogen in a location of ...
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When a star loses temperature its matter loses KE so does it mean the star's gravity weaken?
When a star loses temperature its matter loses KE so does it mean the star's gravity weaken? The question is based on Einstein's field equation which states that energy also contributes in space-time ...
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When Sun was forming and before nuclear reactions inside the core what should have been its surface temperature?
When the Sun was forming and before all the nuclear reactions started inside its core, what should have been its surface temperature (only due to gas friction)?
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In the far future, when the sky is devoid of stars, will a sufficiently advanced civilization be able to discover the big bang [closed]
In the far future, when most of the stars have expanded away and the only ones visible in the observable universe are those in the host galaxy, will there be any obvious clues (assuming there are no ...
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Rotational energy of stellar remnants
The theoretical maximum rotational energy a black-hole can have is 29% of its rest mass. We've often observed remnant black-holes spinning at nearly the speed of light. From this we conclude that ...
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What is the process of star formation? [closed]
What is the process of star formation and what happens to stars after their death?
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Evaporation of a gravitationally-bound spherical cloud of a warm ideal gas in a vacuum
It seems that for any gravitationally bound system with a very large number of atoms/particles, there will always be some particles that manage to achieve escape speed and ultimately leave the cloud. ...
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Star formation rate in different galaxies
I was looking for some scale to compare my result of star formation rate and see if it is moderate or high or low. But I couldn't find any scale. Is there any paper related to such scale where Star ...
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How does metallicity affect stellar evolution?
The main sequence evolution of a solitary star depends most of all on its initial mass. Other factors influencing its evolution are the initial metallicity, rotation and magnetism.
Question: how does ...
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Death of Stars and Red Giants [duplicate]
As a matter of fact, I was learning stellar astrophysics where I couldn't understand the chain of events at the time of death of stars,
Once the hydrogen fuel core is exhausted, the stars start ...
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Why don't baby black holes give off a lot of Hawking radiation and vanish before having the chance to grow?
Is it because they eat more than they eject? Or something else?
Edit -------
I mean black holes which have just started forming from stellar collapse. Should had mentioned this.
Edit 2 -----
When you ...
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How big should a star be to turn into a black hole?
My initial calculations show that if the radius of a star $-$ with a uniform mass density of $\rho$ $-$ is greater than $\frac{c}{2\sqrt{\pi G\rho/3}}$, the star would collapse into a black hole. ...
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Why does nature have higher atomic nuclei if Iron(Fe) has higher binding energy per nucleon? [duplicate]
From the binding energy per nucleon (B.E./A) vs atomic number (Z) we know that Iron (Fe) is most stable nuclei in the nature. Here comes the question that if nature has found the stable nuclei then ...
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Could you know in advance specifically when a star will go supernova?
I've been thinking about star trek 2009 and star trek Picard in which they happen to talk about a sun inside a fictional solar system which goes supernova destroying a particularly important planet to ...
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Why don't main sequence stars continuously expand?
I understand main sequence stars become subgiant when hydrogen is depleted in their cores and they start hydrogen shell burning. But I don't understand why this process is divided into two distinct ...
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Mass gap between neutron stars and black holes
From the detection of gravitational waves in GW190814, the merging of a 2.6 solar mass compact object with a heavier object has been inferred. The lighter object is in the "mass gap" between ...
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What causes highly compacted matter to collapse into a black hole? [duplicate]
"The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole".
Why does this happen? I mean, why something finite (like the core of a very ...
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When do planets formed via core accretion in a proto-planetary disk stop gaining mass?
I was just trying to go over some of the contents in my exo planets course and wanted to know that if all the planets that form via core accretion continue to attract all the dust in a proto-planetary ...
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What will be the mass of the sun when the core is depleted of hydrogen about 5 billion years from now?
Our sun converts 600 million tons of H to He every second, that is 5 million tons of matter into energy through nuclear fission. However, as the core of the sun continues to shrink the outer layers of ...
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Understanding the Chandrasekhar limit for white dwarfs and its relation with supernovas
So if I understand correctly, the Chandrasekhar limit ($\sim 1.4 \ M_{\odot}$) is the maximum mass that a white dwarf can have. Beyond this mass, the degeneracy pressure of the electrons can no longer ...
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Why do main sequence stars get bigger and more luminous as they age?
As stars age, the concentration of hydrogen in the core decreases, which lowers the power output, causing an imbalance between outward radiation pressure and inward gravitational pressure. This causes ...
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How long from star collapse to supernova explosion?
According to some reports, Betelgeuse might "be ready to explode into a supernova". It's luminosity has decreased "considerably" in the recent weeks.
If we consider the "stable period" as that when ...
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Evolution of red dwarf stars
While low mass stars (initial mass approximately $0.1 M_\odot$ to $0.8 M_\odot$) are quite numerous, their evolution seems to draw relatively little attention. The lower central density and ...
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Why do later fusion stages in a star last shorter?
When most of the hydrogen in the core of a massive star has fused to form helium, the next fusion stages (helium, carbon, neon, oxygen, ...) produce less and less energy in a single fusion reaction. ...
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Existence and evolution of P-type "asymmetrical binaries"
I'm not sure how those are called so let me explain what I mean by "P-type asymmetrical binaries" - I'm thinking of two stars of very different masses (originally) that orbit each-other fairly closely....
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Why do Type II supernova happen? [duplicate]
I am an engineer and not a physicist. I am unable to understand why SuperNova happen.
I understand that when the core is composed of high atomic number of elements like Iron and further fusion is not ...
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Temperature function for stars?
I was thinking that for a star to be stable, the rate of energy emittance through a shell of radius r is constant, otherwise there would be a buildup of energy which would change the temperature and ...
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What conditions provide the oldest star?
If we define the start of the lifetime the protostar and the end of the lifetime a red giant (at max volume), what conditions would make this time the longest when the star was first formed and ...
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