Questions tagged [red-giant]
Questions about red giants, large luminous low-mass stars in a late phase of stellar evolution.
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Red dwarfs and red giants
I have a quick question. I have heard that red dwarfs that are approximately less than 0.35-0.5 solar masses are fully convective, meaning that they do not become red giants. I have also heard that ...
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Why does the core-mass luminosity relation work?
Why is luminosity of a star with degenerate core and He or H shell burning (RG, AGB or between Post-AGB and PN phase) given solely by the core mass? I understand that the relation is a stable result ...
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What happens to planets after they get swallowed by red giants?
You often hear about the Sun going to be a red giant in a few billion years and engulfing Mercury, Venus and finally Earth. But what happens to the planets after they get engulfed?
How long will they ...
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Solar System Replacement?
After a star becomes a red giant, most if not all of the planets orbiting it are usually destroyed. However, the red giant is still quite huge and can be orbited. Let's say a solar system is divided ...
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Has anyone simulated how long the earth would last if/when engulfed by our sun turning red giant?
By "last" I'm not talking about survival of life. I know the Earth will be totally unlivable well before the sun swells into a red giant.
I'm talking about the whole planet being vaporized ...
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Why does the blue loop occur?
I understand that the blue loop is a loop in the HR diagram performed by stars from 2-8 solar masses. I was curious as to why they occur, but when I researched all I got is that it is when the star ...
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When a star enters a red giant phase, does the pressure in its core increase or decrease?
When a star becomes a red giant, does the pressure in its core increase or decrease?
From one side, the only source of pressure in a star is gravity. A red giant is much larger than an ordinary star, ...
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Hayashi Track vs Red Giant branch
Are the red Giant branch and the Hayashi track the same thing? After doing some research, I found some similarities between the two, such as both aree fully convective. However, the T Tauri phase does ...
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Where will all atoms on the Earth end up when the Sun engulfs the earth?
I am curious about what will happen to all atoms on the Earth including all of our atoms after the Sun engulfs the Earth?
Will they become the part of the Sun's white dwarf?
Or most of them will be ...
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How to predict the radius of a Red giant
I am working on a sci-fi that goes over such a large length of time that I will be having stars dying out, and this raises a question that I would need to find an answer to.
How can one predict the ...
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How did we figure out that Stars become red giants and when did we find out that they will?
I always hear that the Sun will be one but never when we found that out or how.
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What are the primary astrophysical implications of a proposed mass of about 11 M⊙ for the SN 2023ixf progenitor?
The abstract of the arXiv preprint SN 2023ixf in Messier 101: A Variable Red Supergiant as the Progenitor Candidate to a Type II Supernova (itself recently "discovered" in the observatory) ...
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How do they see BOTH "anomalously cool with a significant mid-IR excess" rather than one or the other? (SN 2023ixf progenitor)
The abstract of the arXiv preprint SN 2023ixf in Messier 101: A Variable Red Supergiant as the Progenitor Candidate to a Type II Supernova (itself recently "discovered" in the observatory) ...
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Radius and surface temp of red giant Sun [duplicate]
There is wildly conflicting information going around about the predicted parameters of the Sun as a red giant. The estimates for the radius vary from 100 to even 256 solar radii (with the larger ...
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Are red giants still primarily made of hydrogen? What is their exact composition?
How much lower is the ratio of hydrogen to helium in a red giant vs a 'normal' main sequence star like our Sun?
Also, how low does the ratio get at the end of a red giant's life? (Just before it ...
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Which star has a higher effective temperature, a red dwarf or a red giant?
According to the Hertzsprung-Russell diagram, they would roughly have the same temperature, but I've read in bibliography that the surface temperature of the red giant is about 5000K
and the one of ...
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Can a brown dwarf accrete enough mass from red giant to become a star?
Let's assume a brown dwarf is on orbit around a main sequence star. Than the star becomes a red giant.
Let's assume the brown dwarf has "the right" orbit and can syphon matter from the red ...
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How can I calculate evolutionary timescales of low mass stars?
How can I calculate how long a star of a given mass will spend on an evolutionary branch before evolving off it?
I'm thinking about the evolution of low mass stars from the subgiant branch to the red ...
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How hot would the core of the Red Giant Sun be?
After the Sun becomes a red giant, it will heat up its core to 100 million kelvins, which initiates the Triple-Alpha fusion process, which heats up the star's core even further and cause it to undergo ...
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Are there any binary red supergiants?
I wonder if we ever have identified or observed a pair of binary stars (red supergiants). And I also wonder what would happen if they exploded, (theoretically) as we haven’t observed it. Also, would ...
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How bright will Alpha Centauri A be from Earth when it becomes a red giant?
As of right now, both stars from Alpha Centauri are in their main sequence stages, but eventually Alpha Centauri A is going to quickly expand in a matter of time, and I’m pretty sure its luminosity is ...
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Source of information on density profile of a red giant star?
Is there a good source of information of the expected density profile inside a red giant star?
I have read that when a star such as the sun has converted much or most of the hydrogen in its core into ...
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How much of the earth would remain intact if the sun expanded into a red giant encompassing its orbit?
It seems to me that part of the earth might survive being absorbed by a red giant. How long would it take the heat, plasma, magnetic field, etc. of the sun to eat away at the earth? How long could it ...
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Does a red giant star produce more stellar wind than a yellow star?
Do red giant stars produce more stellar wind than
when they were ordinary yellow stars? If so, how big a difference are we talking about?
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How much mass is lost in the red giant phase of a star?
The red giant phase of stars are relatively fast. How will this impact a star's total mass? Are there significant mass losses taking place when this happens? If so, do we know how much? The sizes of ...
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Will the planets be pushed outwards when the Sun becomes a red giant?
When the Sun becomes a red giant will the planets be pushed outwards towards the periphery of the Solar System?
If so, will this happen simultaneously for all planets or could, for example, a planet ...
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What exactly will happen when the Sun leaves the main sequence? I know it expands to a red giant twice, but what happens exactly? What's the timeline? [duplicate]
I've seen numerous claims surrounding this, with some claiming the expansion of the Sun from its end-main sequence radius to its peak red giant radius will take over 1 billion years, while others ...
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Dynamics of red giant hydrogen shell
From what I understood from this answer to How can a red giant grow so big?
But this is not at all the way the shell fusing in a red giant self-regulates its fusion rate-- it cannot regulate its ...
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Where will the frost line be when the Sun becomes a red giant and what effect will it have on the solar system?
I understand the frost line is currently about 5.2 AU and earlier in the solar systems formation was 2.7 AU. But when the Sun becomes a red giant the frost line should move outward. I understand the ...
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Why red giants have cooler surface than MS stars?
I know that with increasing age and depletion of hydrogen in the core the radiation inside a main sequence (MS) star increases pushing the envelope/surface of the star outwards. What I don't ...
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What is the theoretical maximum variability a pulsating red giant can have such that a habitable planet can stay habitable for long periods of time?
I was reading about red giants and came across this statement:
Some research suggests that, during the evolution of a 1 M☉ star along the red-giant branch, it could harbor a habitable zone for ...
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Do low-mass red giants last longer than high-mass red giants?
It turns out that red giant stars are not defined by uniform mass. Some can be only one-third as massive as our sun, whereas others can be eight times as massive. So I'm calling the both sides "...
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Is a star with 2/3 solar masses and 9/10 solar radii still in the main sequence?
As far as I know, K-type and G-type stars (among others) grow in radius as they age, eventually leading to red giant phases.
My question is, would a star that is about 0.66 solar masses and 0.94 solar ...
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How does the stellar evolution for low and intermediate mass stars differ?
I'm trying to understand stellar evolutionary tracks for different masses. So far I have the general understanding from a cloud of gas and dust to a white dwarf, neutron star or black hole.
What I don'...
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Exactly how long does it take for the exposed core of a star to cool from its starting temperature (several billion K) to ~50,000 K?
OK, I didn't know how I should word this question. But the basic point is that most white dwarfs that we have classified fall in temperature ranges from ~50,000 K to 6000 K. However, at the end of a ...
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How large will our Sun get during the red giant phase (ie which planets will it engulf) before the helium flash?
I have read that our Sun will increase in size to a red giant. But after it goes through the helium flash it will contract somewhat. Then after that grow again to be even larger before finally ...
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What would a red giant Sun look like from Proxima b?
As of now, Proxima b is the only confirmed planet (or dwarf planet if it didn't clear its orbit - sorry, couldn't resist) around Proxima Centauri, the nearest-known star to the Sun about 4.2 ly away. ...
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If Sunlike stars become a red giant and eventually a white dwarf, what do red dwarfs become?
The Sun is said to become a red giant at the end of its life (before that it will become an orange subgiant first and then an orange giant or so) and after ejecting its outer layers it should become a ...
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Could the Sun's planetary nebula be dangerous for the planets?
Since the Sun's mass isn't high enough it won't go supernova being a red giant but instead release a planetary nebula. So that seems to be kind of a substitute for a supernova. Would ejecting the ...
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Do we know a star that is similar to the Sun when it would be a red giant?
In about 5 billion years the Sun is predicted to become a red giant and have more than 200 times its current size, reaching a radius of about 5 AU when largest.
I wonder what spectral class the Sun ...
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How would the sky look if Earth orbited a red giant at a safe distance?
Let's say that instead of the sun, we have a red giant, but are orbiting it at a safe distance, within the goldilocks zone. Would the sky actually look more red? Or would it be closer to white/...
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What if the Sun turned into a red giant tomorrow? [closed]
Let's say that, hypothetically, our sun uses up all of it's hydrogen tonight, and tomorrow morning is the first day of its red giant phase. How long would it take for the star to turn red? How long ...
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Relation between initial mass and evolutionary phases lifetimes
Consider the following image (Source: An Introduction to Modern Astrophysics):
There seems to be a relation between the initial mass/mass at the beginning of the MS and the time spent during ...
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How Long Will Earth's Year be When Our Sun Goes Red?
We live in a planet that orbits 93 million miles from a G-type main-sequence star, or "yellow dwarf". That is far enough for a revolution of 365 days. Such is the case of Kepler's Third Law of ...
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How Wide Would the Habitable Zone Be in a Singular Red Giant System?
Astrobiologists looking for signs of life outside Earth usually take excitement over planets orbiting red giant stars because a larger, brighter star usually means a farther-away but still wider ...
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In System KIC 9246715, How Far Does One Star Orbit the Other?
I was going to ask if it's physically possible for one red giant to orbit another, but fortunately, I have just found such a thing--a red giant binary system known only as KIC 9246715. In this ...
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Is there a theoretical minimum mass main sequence star that can become a red giant?
Wikipedia's Red Giant page says they range in mass from 0.3 to 0.8 solar masses. Which corresponds to an initial mass of a bit less than 1 solar mass, about 0.8 or so, if I was to estimate and a few ...
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What will be the temperature on Earth when Sun finishes its main sequence?
We know that presently Sun is 4.5 billion years into its main sequence. It has another 5 billion years before it enters the Red Giant phase. We also know that Sun's luminosity increases by 10% every ...
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How long does it take a star to transition from main sequence to red giant?
I have read that it takes billions of years for stars of approximately the size of the Sun to get through the main sequence, after which it will enter the red giant phase. When that happens, how long ...
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How fast will the sun grow when it becomes a red giant?
We all know that our sun will become a red giant in a couple of billion years? But how fast will the process be when it starts? Would it be theoretically possible (disregarding the deadly effects of ...
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