Questions tagged [star-formation]

Questions related to the physical processes involved in or to the observations of the process of forming a star.

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How can you tell the rough phase of star formation a star is in from the current radius and mass of the star?

This question is really bothering me since I'm getting mixed thoughts. The masses of the stars in question are 0.92 solar masses and 0.29 solar masses. The diameters are 1,400,000 km and 750,000 km ...
Henlo Jibbab's user avatar
1 vote
1 answer
1k views

Relation between absolute magnitude of UV and star formation rate

I surfed the internet and searched a lot of sites, so far I got this but unable to find the formula which relates only Muv and the Ψ as I don't know the value of parameters Auv and μ(z). If there ...
Nitin Kumar Chauhan's user avatar
2 votes
1 answer
2k views

Why do stars rotate slower than they're expected to?

Due to conservation of angular momentum, I thought most stars would be spinning extremely fast because they have a relatively small diameter. However, it turns out that this is not true and most stars ...
Henlo Jibbab's user avatar
2 votes
1 answer
1k views

Will the Sagittarius A* Black Hole eventually swallow the entire Galaxy?

In one of his interviews, Sir Roger Penrose mentioned that when the Milky Way and the Andromeda galaxies eventually "collide" and merge into one, their super-massive black holes will also ...
Jan Stuller's user avatar
14 votes
2 answers
4k views

How can many stars be formed from the remains of one supernova?

A supernova is the explosion of a single star; so how is it that thousands of stars can "be born of" that one explosion (presumably only using the unspent fuel / lighter elements of the ...
Still.Tony's user avatar
2 votes
0 answers
36 views

Is the magnetic field strength of a star predictable from mass, composition, age and angular momentum alone?

This answer to Which stellar properties can we describe as “first principles” in which we can derive the rest? contains an intriguing bit: That states that composition and mass are the two key ...
uhoh's user avatar
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3 votes
1 answer
114 views

Galactic winds/outflows: why and how are they detected via blueshifted absorption lines in spectra?

I know that galaxies can eject gas due to supernovae, accreting black holes, etc. These galactic "winds/outflows" are often defined/detected observationally using blueshifted absorption ...
quantumflash's user avatar
6 votes
0 answers
45 views

Are metallicities of molecular clouds lower in the outskirts of the galaxy?

(this question was originally posted in an answer by user PSR-1937-21 to another post. I find it an interesting one, but since they don't seem to be active anymore, I'm posting it to see if somebody ...
SE - stop firing the good guys's user avatar
12 votes
1 answer
1k views

Why does a hot cloud need more mass to collapse?

I was wondering why does a hot cloud need more mass to collapse than a cold cloud to form a protostar? Is it because there's a higher thermal pressure inside the hotter cloud than it is in a colder ...
space nerd's user avatar
0 votes
1 answer
52 views

Is it only possible to look at solar systems with stars at least as old as ours to be able to find intelligent life?

Assuming the speed it takes to development intelligent life is the same in all solar systems, would we need to look at exoplanets with stars as old or older than ours to find intelligent life? A young ...
user avatar
1 vote
0 answers
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Supernova impact on Protostar formation

What would be the impact on the formation of a new star (protostar) when a nearby star (within 10 LY) goes supernova? Will the force of the explosion (once it arrives in the Molecular Cloud where the ...
PaulS's user avatar
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12 votes
2 answers
1k views

Why aren't there blue elliptical galaxies or yellow spiral galaxies?

Elliptical galaxies are universally old and yellow; about three-quarters of all ellipticals have no significant star-forming gas or dust left, and even the quarter or so of ellipticals that are still ...
Vikki's user avatar
  • 625
1 vote
2 answers
660 views

In Orion, how close in local distance are the closest of the member stars?

All the members of Orion are within the Milky way, and some of them look pretty close to a neighbor. And could the bow* be an effect similar to the Radcliffe Wave? *shield
Gabe Fernandez's user avatar
2 votes
0 answers
47 views

Why does the star formation rate correlate with the total stellar mass in star forming galaxies?

The so-called "Main Sequence" of star-forming galaxies (e.g., Brinchmann et al. 2004; Noeske et al. 2007) clearly points to a linear relation between the stellar mass of galaxies and their star ...
user avatar
4 votes
1 answer
875 views

What is the difference between emission line and recombination line?

When an electron jumps from higher level to lower level a photon is emitted. This is seen as an emission line. But what exactly is a recombination line? I found them similar. Can you please tell me ...
Rian's user avatar
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1 answer
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Very Old Stars in the Universe [duplicate]

How could a Star possibly be older than the Universe ? Is this possible or are the calculations off when determining the age of such Stars ? Can a Star exist that formed on its own independent of a ...
Peter U's user avatar
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4 votes
1 answer
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What exactly are infrared dark clouds and what is the significance of the orientation of their magnetic fields?

In the video Why NASA's SOFIA Telescope On A Plane is "Perfectly Balanced" after about 10:04 SOFIA associate director James Jackson says: We have a ...
uhoh's user avatar
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6 votes
1 answer
205 views

How much of a molecular cloud can end up as "starstuff"?

Stars form within molecular clouds. These clouds can be up to 6 millions solar masses. When the cloud collapses into stars, is it possible to know a rough figure for how much of this material actually ...
usernumber's user avatar
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2 votes
0 answers
113 views

Freefall timescale for a Jeans-unstable hydrogen cloud of mass M

I'm working on a project (personal, not academic) that involves calculating the collapse timescales for protostars which will end up becoming stars of varying given masses. I'm treating the pre-main ...
realityChemist's user avatar
4 votes
1 answer
240 views

Will the conditions that allow life to evolve still be around in a trillion years?

Some billions of years ago, systems like the Earth couldn't emerge and therefore life couldn't arise, because not enough of the heavy elements had formed yet. Assuming there'll neither be a big ...
Valdegg's user avatar
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4 votes
1 answer
1k views

Estimating a star's radius, temperature, and luminosity based on its mass

(See updated figure and description below.) I've been trying to generate ballpark estimates for the radius, temperature and luminosity of stars in the main sequence based solely on their masses (...
Bryan Wright's user avatar
16 votes
2 answers
843 views

Characteristics of the first planets in the Universe?

What would have the very first planets looked like, based on their most likely chemical compositions? For example: Were they mostly grey gas giants with atmospheres of hydrogen and helium, ...
Dave Jarvis's user avatar
3 votes
0 answers
64 views

How many parent stars contributed to our solar system? [duplicate]

All of the stuff that isn't hydrogen and helium (which came from the Big Bang), that coalesced to form our solar system (the iron, the sulfur, the water, and so forth) all came from previous ...
Pete's user avatar
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6 votes
1 answer
310 views

Formation of the First Stars

I've got a few questions about the first stars to form in the universe. First off how might metalicity have impacted the formation of the first stars and also what effect would the absence of metals ...
PSR-1937-21's user avatar
4 votes
1 answer
104 views

How to model and subtract nebular emission lines from stellar spectrum

I have optical stellar spectra from a star forming region with spatially varying nebular background. I want to subtract the nebular lines from the stellar spectra (which are varying in intensity from ...
pziphi's user avatar
  • 71
12 votes
2 answers
398 views

What will future populations of stars be like?

As stars slowly using up hydrogen and ejecting heavier elements into space, the future stars will form from nebulae that are more metal and helium rich. The question is: how does the increased ratio ...
Calmarius's user avatar
  • 281
2 votes
0 answers
1k views

What is the physical reason of the mirror principle in the stellar evolution?

I understand that stars transition into the red giant phase by obeying the mirror principle, as written here: Shell-burning stars obey something called the mirror principle, which is an observation ...
Vin's user avatar
  • 121
0 votes
0 answers
100 views

Stars readjusting themselves in the sky [duplicate]

I had a meeting in the evening and thought of grabbing a snack before that. I stepped out of the office along with a colleague. He was on his phone and I was simply staring at the sky wishing it would ...
Shreya Paul's user avatar
4 votes
0 answers
78 views

Do stars come on like LEDs or wick lamps? [duplicate]

Is stellar ignition an instantaneous thing - before, dark, after, shining brightly - or more of a process over time? In fusion research 'ignition' appears to be an event, but maybe in a protostar it ...
Andrew's user avatar
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1 vote
0 answers
63 views

What is the most mass that matter likely to form?

If we plot graph between accumulate of forming mass (y-axis) and mass (x-axis), where is the maximum ? There is a story how I get this question. It start when I think about question "Is our sun is ...
Ro Theory's user avatar
  • 169
0 votes
1 answer
693 views

What is the lyman-werner background?

I've seen several papers that discuss the Lyman-Werner Background (LWB) when modeling star and galaxy formation in the early universe. One in particular (https://arxiv.org/abs/1803.04527) even varies ...
NotSoSN's user avatar
  • 437
0 votes
1 answer
138 views

How could a supernova seed solar nebula?

If the heavier elements such as Uranium came from a supernova, then this supernova had to sit somewhere right in the middle of the original solar nebula, because although the ejected matter traveled ...
Meatball Princess's user avatar
1 vote
2 answers
339 views

Why does star formation cease?

The universe is expected to have a time when star formation slowly ceases. However, this seems bizarre as there is always an abundant amount of matter in the Universe. Massive amounts of hydrogen ...
Max0815's user avatar
  • 1,862
4 votes
1 answer
82 views

Stellar nurseries in the "Shedding New Light on the Whirlpool Galaxy" video

Captions in the Hubble Space Telescope YouTube channel video Shedding New Light on the Whirlpool Galaxy say: (visible) Along the dark dust lanes, bright pink nebulae are the birthplace of new stars. (...
uhoh's user avatar
  • 31.1k
17 votes
2 answers
4k views

Could stars form outside of galaxies?

Is it possible for there to be a dense enough nebula to form stars outside of any galaxy? Does a galaxy have a minimum size to produce stars? Or could you have a few dozen stars clustered together by ...
Lorry Laurence mcLarry's user avatar
6 votes
1 answer
105 views

Activity of M dwarf stars

Why are M dwarf stars the most active (in terms of starspots and faculae) of all stars?
user4437416's user avatar
3 votes
2 answers
332 views

A few questions regarding the transit of planets

Here we will be concerning ourselves with the transit of a planet with it's parent sun. I have a few questions that I am not sure about: 1) Do all planets transit their parent sun? It would seem to ...
K Split X's user avatar
  • 1,069
2 votes
2 answers
638 views

Remains of the progenitor of the Sun

It has been argued that it is not possible to trace back the remains of the progenitor star of the Sun (sometimes called Coatlicue), which, being estimated in the mass range of 30 $M_{\odot}$, should ...
Stefano Zunino's user avatar
6 votes
4 answers
696 views

Can a donut-shape planet or star be formed?

How stable is a donut-shaped star or planet configuration and under what conditions such object may form? Is there any evidence suggesting that such objects might exist?
user3715778's user avatar
1 vote
3 answers
353 views

Is there any definitive proof of stars being "born" in nebula formations?

Is there any absolute evidence of star formation inside of nebulae (AKA stellar nurseries) as is suggested and even stated as fact by many textbooks?
Bucky Rogerson's user avatar
6 votes
2 answers
279 views

The formation of new stars as depicted in Feynman's lectures

I've stumbled upon this curious passage addressing the formation of stars in Feynman's lectures on physics: Whether we have ever seen a star form or not is still debatable. Figure 7–12 shows the ...
Vlas Sokolov's user avatar
6 votes
2 answers
2k views

What does the ']' in the spectral line "CIII] 1909 Å" mean?

The above emission line, as I understand, is a useful probe of early star-forming galaxies. However, I do not understand what the ']' to the right of the 'CIII' means. I could not find any online ...
H3007's user avatar
  • 63
-7 votes
1 answer
214 views

Black-hole becoming a star again - follow-up question [closed]

Some questions have been posed about black holes becoming stars again once they attract enough hydrogen/atomic matter from another star. Some answers were a forceful NO. Never. However - let's ponder ...
SMF_USR's user avatar
2 votes
0 answers
68 views

What's the profound reason(s) why the star formation rate drives the scatter of the mass-metallicity relation in galaxies?

Since decades it's well known that a correlation between stellar mass and metallicity (Z; both stellar and gas-phase Z, but here I focus on the gas-phase Z) exists (e.g., Tremonti+04; analysis of >...
user avatar
5 votes
1 answer
342 views

Black Dwarf Capabilities

Can a black dwarf be suitable for manned exploration, once it cools down? And potentially used for space mining?
Jay's user avatar
  • 153
10 votes
2 answers
193 views

Star formation around rotating black holes?

Please excuse an amateur question. While trying to think of anything but what was happening during a dental procedure my mind turned to a model of a star close to a rotating black hole and the ...
FlipC's user avatar
  • 103
1 vote
0 answers
57 views

Doubt about star formation [duplicate]

When a star runs out of hydrogen, it either goes through supernova or forms white dwarf and planetary nebula. So there should not be much hydrogen left to form a new star in the nebula. So how new ...
soumya's user avatar
  • 11
32 votes
1 answer
6k views

If two white dwarfs collided, would they become a star?

Would the temperatures during such a collision be able to ignite nuclear fusion, bringing the dead star back to life? If so, would it only be able to fuse for a short time before running out of fuel, ...
Gliese's user avatar
  • 831
2 votes
2 answers
210 views

Will all of the gas in the universe be converted into red dwarf stars?

Red dwarfs have lifespans of trillions of years and are also the most abundant stars, making up 70% of the stars in the Milky Way. No red dwarf star has ever died and none will die for a very, very ...
Gliese's user avatar
  • 831
3 votes
1 answer
94 views

Is the ratio $L_B / L_{H\alpha}$ important to determine star formation rates?

Could someone please tell me if the ratio $$\frac{L_B}{L_{H\alpha}}$$ is important in determining star formation rates? Additionally, could someone please explain the implication of the ratio to me or ...
Constantine 's user avatar