I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
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@vicgrinberg @sianderl @ec_euclid
OK, but many thanks for your answer anyway!
Mhm, another question regarding red dwarfs (like Proxima Centauri):
Red dwarfs may sound harmless at first, but they are much more dangerous for nearby planets (and any potential life) due to intense flares and CMEs, as well as strong magnetic fields that fluctuate considerably.
Is the only reason for this that heat transfer in these stars is convective (meaning the interior is well “stirred up” and therefore rather inhomogenous ) or are there further reasons for this behaviour?
In stars like the Sun, heat transfer occurs internally via radiation and in the outer layers via convection, without things being so uncomfortable all around....
@echopapa it's the convection and the often fast rotation - both tend to tangle the magnetic fields more leading to a higher flare rate. Very close in exoplanets could also trigger flares, again via magnetic interaction https://www.skyatnightmagazine.com/space-science/exoplanets-close-cause-solar-flares
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg there's a legend about Sirius A that used to be red before being blue. Is there any way for stars, aside from aging, to "suddenly" or not-so-suddenly change color in their lifetime?
I mostly have in mind depictions from movies where a star gets eaten by star-goo and turns green; or a "supernova-weapon" turns it an otherworldly color before it, well, goes supernova.
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@vicgrinberg Can something be a star and a black hole at the same time?
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg do most stars generate energy from nuclear fusion of hydrogen (as I understand it, like our sun) and other increasingly heavy elements? Are there other sources of energy harnessed by stars?
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg upper mass limit? Eddington limit still a thing? Deneb is my spirit star (Actually Vega, but that’s not high mass)
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@vicgrinberg what would happen to your arm if you raised it while the lightspeed is 0?
@trrektor
If light speed were zero humans would not exist and not have arms.
@vicgrinberg -
@vicgrinberg That makes sense. Would heavier metals be expected in the cores of gas and ice giant planets?
@Enema_Cowboy likely yes - but it's not that simple, eg NASA's Juno found that Jupiter core is rather "fuzzy" and not just a ball of heavy elements https://science.nasa.gov/jupiter/jupiter-facts/
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
what's the biggest star system seen?
what's the biggest star system theoretically?
i was reading about Nu Scorpii the other day, a seven star system, which blew my mind
besides the stable binary star systems, are all large star systems simply young star systems bound to break up?
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg we have several evocative descriptions of what space smells like https://www.mentalfloss.com/science/space/what-outer-space-smells-like
But, what about the stars you study? What's their scent?
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg How bad has Starlink become to hinder professional examination of the stars from earth or does it all depend on the space telescopes now?
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@trrektor
If light speed were zero humans would not exist and not have arms.
@vicgrinberg@notsoloud @vicgrinberg nah in this example it's turned to zero while existing
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg How much impact does dark matter have on stars? (Does the extra gravity influence internal processes, the number of CMEs, etc.) How much does it vary based upon the star's size? Is there the same relative regular matter to dark matter ratio regardless of size?
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg Maybe more of a physics question than a star question; if so, I apologize: what is your take on the new possibility that black holes may not contain singularities after all?
https://www.sciencenewstoday.org/no-more-singularity-physicists-propose-new-black-hole-paradigms
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg How rare is gold in the universe.
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
Since I have not seen the question already: What are those winds you mentioned? How can I imagine them? I suspect stars don't have an atmosphere like planets do.
I am so confused.
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@johnnythan thanks for boosting - and it's also interesting for me to know that folks know nothing about stars. I'm so used to people knowing a lot about them in my everyday life
@vicgrinberg @johnnythan This XKCD is more accurate than one might think. I've been guilty of it too.
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@quixoticgeek it's going to be pretty much the same - the stars are very far away and our atmosphere very thin, so get to outside of it does not change much in what we see. What we get rid off are the effect of the atmosphere - the twinkling is because of atmospheric effects (similar effect to warm air above a hot street), the stars themselves don't twinkle! So the view is in a way clearer.
@vicgrinberg In this year of our lord 2026 with that monstrosity in office I did not need to know that not only will there be no shining city on the hill if we can’t get the votes to save democracy but the stars don’t actually twinkle. @quixoticgeek
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg I've always thought the ability of gas & plasma to sustain shockwaves means they can actually carry sound.
one of the more spectacular examples would be the "bounce" of core collapse in a supernova. but years and years after that, the shockwave is still travelling and the gas density is very thin.
does that mean these thin clouds of gas can carry sound? are the remnants dense enough to carry it? your work is with stellar winds, does it have sound? does a corona carry sound? the gas "leak" from a cataclysmic variable, what about that...
(I am not a professional astrophysicist, but I sure wanted to be one.)
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I have a bit of time on my hands, so let's do another 24h round of #AskAnAstrophysicist, but this time it's a thematic one.
What do you want to ask an astrophysicist about stars? (I am a professional astrophysicist, part of whose work concerns itself with high mass stars & their winds and I've also taught a variety of astro university courses)
Boosts welcome. I may not be able to reply to all in case of many questions.
@vicgrinberg I know this may go unnoticed. Which is fine. Totally fine. At least I'm willing to try. Anyways, this is how I describe the physics of the Milky Way galaxy in the natural Universe. Is this:
Galaxies hold shape and rotation due to the Tropic Field Extremum's gravitational entrainment upon the stellar mass that is stabilized by the angular momentum trajectory of the host galaxy.
**Tropic Field Extremum**: is the gravitational "bowl" (not) a singularity. Like a skate bowl at a park. -
@Enema_Cowboy likely yes - but it's not that simple, eg NASA's Juno found that Jupiter core is rather "fuzzy" and not just a ball of heavy elements https://science.nasa.gov/jupiter/jupiter-facts/
@vicgrinberg Wow, I'm amazed that the structure of core could be detected.
