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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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79
votes
6answers
6k views

Does the Sun rotate?

The planets rotate as an after effect of their creation, the dust clouds that compressed span as they did so and the inertia has kept it rotating ever since. It's fairly easy to prove that planetary ...
31
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1answer
5k 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, ...
16
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2answers
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 ...
15
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2answers
573 views

Will new stars stop forming at some point of time?

New stars keep forming in the universe thanks to all the nebulae. Now, we need Hydrogen to form stars and there would a time when all the hydrogen will get exhausted, and no more star formation will ...
14
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3answers
1k views

Which stars did the Sun form with?

The Sun formed 4.5 billion years ago, in a molecular cloud. I assume that there were other stars in the vicinity (as is common in molecular clouds). Which stars are they? Where are they now? Are they ...
14
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2answers
348 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, ...
13
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1answer
169 views

Mechanisms of binary/multiple star formation

What are mechanisms of binary/multiple star formation in different mass ranges (low, intermediate and high stellar masses)?
12
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2answers
1k views

How did the lighter elements end up in the center of the solar system? Solar System Formation

The previous generation of stars famously are the origin of all the heavier elements (up until iron?) in the solar system. So a big portion of the solar system mass actually is made up of Carbon, ...
12
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2answers
249 views

Can protoplanetary disks form main-sequence stars?

As has been pointed out by @Envite in the context of a more general discussion (see Generalised planets?), there seems to be a moderate possibility for protoplanetary discs forming main-sequence stars ...
12
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2answers
2k views

How are binary star systems created?

I don't know how common it is for a system to have two stars (or perhaps even more) but how do they arise? Is that due to the stellar accretion disc, or the composition of the stellar nebula? Or are ...
12
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2answers
195 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 ...
10
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2answers
135 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 ...
8
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2answers
651 views

What causes jets from newly born stars?

Newly born stars often have bilateral jets of gas ejected from them at high speeds (hundreds of km per seconds), often ending in Herbig-Haro objects. As I understand it those jets would have something ...
6
votes
1answer
528 views

Mechanism for Brown Dwarf Fusion

I've read (at here, among other places) that during the Degenerate Era, star formation will end and the last stars will go out. But it was noted that there is still the possibility of star birth, ...
6
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2answers
176 views

Can dark matter decrease the Jeans length?

I am wondering if there are any models of interstellar cloud collapse out there which take dark matter into account. If dark matter has local perturbations or density fluctuations, then that may be ...
6
votes
2answers
695 views

How were the first stars formed?

In class, we read a Scientific American article, "Cloudy with a Chance of Stars" that explained how the cores and the dust around them formed stars(he called them eggs for a chicken/egg analogy, where ...
5
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1answer
296 views

Black Dwarf Capabilities

Can a black dwarf be suitable for manned exploration, once it cools down? And potentially used for space mining?
5
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1answer
111 views

How long will star formation endure before the eventual heat death of the observable universe?

Lord Kelvin's prediction of heat death indicates the eventual end to star formation in the observable universe. Have any astrophysicists made any predictions for the endurance of star formation in the ...
5
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1answer
57 views

Activity of M dwarf stars

Why are M dwarf stars the most active (in terms of starspots and faculae) of all stars?
5
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2answers
204 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 ...
5
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2answers
190 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 ...
5
votes
1answer
257 views

What is the origin of the dust near the sun?

In this question I asked about the Solar Probe Plus mission. Reading a 2008 report I saw that there is an elevated exposure to high velocity dust near the sun. I understand the high velocity, anything ...
4
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3answers
2k views

Could the earth become a star if more mass was added?

I've heard that the only difference between a star and a planet is mass, meaning that if planets accredited enough mass they would too become stars. Does this mean that the star started off as a ...
4
votes
2answers
176 views

If two binary brown dwarfs began to exchange gas with each other, would they both ignite into stars?

If two brown dwarfs got close enough to exchange gas with each other, could it trigger nuclear fusion within their cores? Is it possible for two brown dwarfs to orbit so closely and become a ...
4
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3answers
416 views

Are there heavenly bodies between galaxies?

I do understand that galaxies were formed in the famous Big Bang. However, I also understand that if such an explosion occurs in empty space it will never form distinct galaxies, it should more or ...
4
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2answers
378 views

Sun's formation as “part of a star-forming-cluster…”?

After reading this interesting answer, I was wondering, do we in fact know if our Sun in particular was created as part of a star-forming-cluster, or, was it more of a solo creation? (Or, are all ...
4
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1answer
1k views

What is the largest hydrogen-burning star?

I am wondering what is the largest known core hydrogen-burning star? A look at the list of largest known stars on Wikipedia seems to indicate VV Cephei B (at the bottom of the list), but I would like ...
4
votes
1answer
36 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 ...
4
votes
1answer
236 views

Why dust is optically thin in Far Infrared wavelengths?

What is the actual meaning of the statement 'Dust is optically thin in the Far Infrared (FIR) over most of the Galaxy'? Kindly Help
4
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1answer
1k views

Where do new stars get their hydrogen from? [duplicate]

When stars run out of hydrogen, they explode (though they also use heavier elements for some time) and form nebulae. In the nebulae, new stars are born which use hydrogen as their fuel. So, my ...
4
votes
1answer
394 views

Solar System formation, considering its and the universe's age

It is known that the Sun is 4.6 billion years old, and the complete Solar System is of a similar age. The class of stars to which the Sun belongs seems to be quite common. Stars of its class can live ...
4
votes
1answer
238 views

Are there any hot jupiters orbiting red dwarfs?

Do we know of any hot jupiters that could be orbiting a red dwarf (or, more probably, orbiting a barycenter between the two)? Is this scenario even physically possible?
4
votes
1answer
427 views

How is the Lithium Depletion Boundary used to determine the age of a stellar cluster?

According to my understanding of Soderblom et al. (2014), lithium ages of stars are determined as follows: Determine lithium abundance from equivalent width measurement of Li$_{\mathrm{I}}$ ...
4
votes
1answer
153 views

What is the physics of a gas mass subject to gravity in space?

There are many formulas for atmospheric pressure on earth, but how does gas behave in free space? I am thinking about why stars form. I am guessing that the gas density will influence pressure, as ...
4
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0answers
46 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 ...
4
votes
2answers
499 views

How to tell a nebula from a galaxy?

Not all galaxies are spiral in shape[1][2], some nebulae are huge[3] and nebula are the nursery of stars[4]. How to tell them apart? Note I have already compare the contents for galaxy and a nebula, ...
3
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3answers
541 views

What is the difference between LMC and SMC?

Apart from the obvious difference as suggested by their names that the Large Magellanic Cloud is 'larger' than the Small Magellanic Cloud, what are the other differences between them? Do give all the ...
3
votes
5answers
2k views

Why does gravity increase in star formation?

When a star ignites ( ie. fusion starts ), the star maintains its form by balancing gravity's inward pressure, and radiation's outward pressure. I get that the fusion of hydrogen atoms releases ...
3
votes
2answers
477 views

What is meant by “Radial Direction” of a galaxy?

There is a scientific journal article having a line: "In order to study the star formation scenario in the radial direction of the LMC...." What is meant by 'radial direction' of a galaxy ?
3
votes
1answer
56 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....
3
votes
3answers
370 views

How do we calculate heat flow or cooling rate for no fusion brown dwarf star?

I was reading this article and it said something that didn't sit right with me. "SIMP0136 still gives off light mostly in the infrared wavelengths, as its temperature is now approximately 830° C (1,...
3
votes
2answers
127 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 ...
3
votes
1answer
145 views

What are IRAS sources?

Do IRAS sources refer to star forming regions? I searched google and I came to know that it stands for IR astronomical satellite.But what do they search for? Please help me
3
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5answers
2k views

Fusion of elements inside heavy stars

I am confused with nucleosynthesis inside supernovae. I have read that the heavier elements are made through fusion of lighter element's namely hydrogen and helium. Does the star "store" all the ...
3
votes
1answer
124 views

Sky in the very far future / past

Motivated by this question about a stranded submarine in the Jurassic I would like to know: Is there anything remotely left of our current skyline if we go back or forward millions of years so that ...
3
votes
1answer
321 views

Why do pre-main sequence stars show lithium in absorption?

This paper and this paper state without discussion that the presence of lithium absorption in the stars they observe as strong evidence of these stars being pre-main sequence stars. Because they state ...
3
votes
1answer
132 views

What is star composition after formation

Most descriptions of star ignition go something like... The star reaches a critical mass and ignites, blowing away the surrounding material. The most obvious question would be "Why are stars not all ...
3
votes
1answer
161 views

What are infall signatures in stars?

I came across several papers (e.g. Looking for outflow and infall signatures in high mass star forming regions P. D. Klaassen, L. Testi and H. Beuther, 2011) talking about infall signatures in star ...
3
votes
1answer
264 views

How can pre-main sequence stars radiate more energy than main-sequence stars?

How can a pre-main sequence star radiate more energy by gravitational contraction than a main-sequence star can by hydrogen fusion?
3
votes
1answer
59 views

What are possible methods of discerning a starburst AGN composite galaxy?

I'm currently working on an independent project that involves discerning starburst galaxies that are themselves within active galaxies. I would assume radio observations would be best to discern star ...