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 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, ...
lthz's user avatar
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4 votes
2 answers
262 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 ...
Gliese's user avatar
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2 votes
3 answers
438 views

Term for the moment when hydrogen fusion begins in a star

I have read of this process many times, but I don't think I know the term specifically for the moment when hydrogen fusion begins. What is this moment called?
Glacialis's user avatar
2 votes
1 answer
271 views

How was the Sun formed?

Refer to the below minutephysics video, in which they say that in order to reach the Sun from earth, we must first stop revolving around the Sun ie make our tangential velocity zero, and then head ...
amsquareb's user avatar
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3 votes
1 answer
246 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 ...
Rian's user avatar
  • 503
3 votes
3 answers
781 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,...
0tyranny0poverty's user avatar
0 votes
1 answer
133 views

Spacing of G and K class stars

I was looking at the Wikipedia article "List of potentially habitable exoplanets" and I noticed that many of the closest planets listed(tens or hundreds instead of thousands of light-years away) ...
Inflationary_Bubble's user avatar
3 votes
1 answer
155 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
Rian's user avatar
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5 votes
1 answer
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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 ...
James Goetz's user avatar
14 votes
2 answers
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 ...
Marijn 's user avatar
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7 votes
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959 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 ...
rcteg's user avatar
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3 votes
1 answer
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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 ...
Thorsten S.'s user avatar
2 votes
0 answers
496 views

What characteristics or patterns do galaxies have on color-luminosity chart? [closed]

For the following graph, I have some confusions: How do galaxies rank by mass? We know that on main-sequence, more luminous stars are also more massive, so I guess it also applies to galaxies. Do red ...
CoolKid's user avatar
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1 answer
2k views

How do we know a star's age based on its spectrum? [duplicate]

A star's nearby environment may give clue to its age. Different stellar type have different spectral features. If we just have its spectrum, how do we know its age? For example, a star may be born ...
questionhang's user avatar
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0 votes
1 answer
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I have some questions about star formation [closed]

Q2 What does the phrase 'containing several distinct knots of collopsing material' mean? Q3 In this context, does the word 'such clouds' mean protostar? (I'm not an English-native speaker.) Q4 In ...
Purple Rain Kim's user avatar
3 votes
2 answers
459 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 ...
Fattie's user avatar
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9 votes
2 answers
7k views

Which came first: Galaxies <=> Stars <=> Planets?

If a galaxy is defined as a collection of planetary systems (and all matter in between), and a planetary system is defined as a collection of planets circling a star (and all matter in between), and a ...
EveryBitHelps's user avatar
9 votes
1 answer
852 views

What is the origin of the dust near the sun?

note: Solar Probe+ is now officially Parker Solar Probe In How can the Parker Solar Probe survive passing within 4 million miles of the sun's surface? I asked about the Solar Probe Plus mission. ...
uhoh's user avatar
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4 votes
3 answers
4k 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 ...
G. Gip's user avatar
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2 votes
1 answer
495 views

Star formation: When a nebula collapses, is it only the gasses that form the star?

A nebula is made of dust (elements heavier than He and H) and gas (H and He). Stars are made when nebulae's collapse and hydrogen begins to fuse. 99% of nebula material goes into making the star. The ...
G. Gip's user avatar
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1 vote
1 answer
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How to show that the Jeans Criterion for Mass, Radius and Density are equivalent?

The gravitational collapse of a gas cloud can be described by the Jeans Criterion for mass, radius and density of the gas cloud, which is (c stands for cloud): $$M_J = (\frac{5kT}{G \mu m_H})^{3/2} (...
DeltaCentauri's user avatar
1 vote
1 answer
125 views

Luminosity L(t) for a homologously contracting star

I'm dealing with a homologously contracting star with Mass M, Radius R and a gravitational binding energy of $E = -a GM^2 / R $ (a is a constant). I was looking for a way to find an expression ...
DeltaCentauri's user avatar
1 vote
2 answers
255 views

How can we explain high redshift numbers?

I just finished an introductory astrophysics course$^1$ and I have a lingering question that I can't seem to resolve. We learned that for the first few hundred million years, the universe was pretty ...
user01101001's user avatar
4 votes
1 answer
439 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
Rian's user avatar
  • 503
3 votes
1 answer
549 views

What does "EW(Hα)" mean?

I came across a website saying that classical T Tauris have an "EW(Hα) > 5 angstroms". Does anybody know what "EW" means? Thanks.
Jason Yang's user avatar
3 votes
1 answer
223 views

How can ionized emission line flux decrease as a function of increasing metallicity or abundance?

The chemical evolution of galaxies is an important way to learn about their formation and stellar/gaseous constituents. Many galaxies show narrow emission lines at optical wavelengths (3500-9000 ...
quantumflash's user avatar
2 votes
1 answer
77 views

If a star were to suddenly lose nearly all of its stored heat, would it be able to return to its normal state? [closed]

If not, would it be possible to approximate the maximum heat energy a star could lose before the change became irreversible?
AkariAkaori's user avatar
4 votes
1 answer
352 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?
Breaking Bioinformatics's user avatar
2 votes
1 answer
141 views

Could dark matter assist with star formation?

This is related to the question: "Can dark matter decrease the Jeans length?" If dark matter assists in any way with star formation, shouldn't it be detectable by precisely measuring velocities in ...
Jack R. Woods's user avatar
5 votes
1 answer
2k 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 ...
another 'Homo sapien''s user avatar
3 votes
1 answer
517 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 ...
NeutronStar's user avatar
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1 vote
0 answers
41 views

Star Formation in the future [duplicate]

From what I understand stars form in dense clouds of hydrogen and helium molecules. Only so much hydrogen and helium were "created" from the Big Bang or rather formed if you may. Is it conceivably ...
Lucian09474's user avatar
3 votes
1 answer
191 views

Could a "burping" supermassive black hole be responsible for a spiral galaxy's look?

I read an article which suggests black holes could influence the production of stars in the galaxy as the black hole can burst out powerful X-rays to "snowplow" the surrounding dust and gas. Although ...
user6760's user avatar
  • 2,503
2 votes
5 answers
5k 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 ...
Lucian09474's user avatar
8 votes
2 answers
301 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 ...
dualredlaugh's user avatar
3 votes
5 answers
3k 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 ...
user2738698's user avatar
4 votes
1 answer
660 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$_{\mathrm{I}}$ ...
user avatar
4 votes
1 answer
2k 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 ...
NeutronStar's user avatar
  • 2,663
1 vote
1 answer
374 views

What is the mass limit in a stellar accretion disc?

I became curious about the maximum mass in a star's accretion disc while watching an episode of Star Trek involving a Dyson Sphere. I wondered if some maximum amount of stellar material would limit ...
12345678910111213's user avatar
4 votes
3 answers
578 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 ...
Rajneesh Kumar Gobin's user avatar
2 votes
1 answer
5k views

Can a supernova make a new star? [duplicate]

Today I was wondering with a friend about the birth of a star. So we know that stars are born from a nebula, but the residue of a dead star (like a supernova) is itself a nebula. So can a star be born ...
Leo91's user avatar
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2 votes
2 answers
1k views

Star formation analogy

If I have understood correctly, stars form in big clouds of gas and dust that are pulled together by their gravity. And the stars are often ignited when something disturbs the cloud, such as a passing ...
Lii's user avatar
  • 121
2 votes
1 answer
93 views

What is a typical value for core-to-star efficiency?

I was reading Unfolding the Laws of Star Formation: The Density Distribution of Molecular Clouds by Kainulainen et al., which discusses star formation rates and efficiencies. One variable used is $\...
HDE 226868's user avatar
  • 36.6k
4 votes
2 answers
570 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, ...
user6760's user avatar
  • 2,503
2 votes
2 answers
2k views

What is the minimum size of a ball of gas to become a star?

I know there are two criteria to meet in order for nuclear fusion to occurs. High temperature (many times temperature at Sun's core) High pressure (protons are very close to each other) [Goal] ...
user6760's user avatar
  • 2,503
1 vote
1 answer
94 views

Simulation packages or theory to work with gravitational collapse of massive molecular clouds?

So, I am getting interested in gravitational collapse of large molecular clouds that fragment and collapse into multiple stars. Are there well-known popular academic simulation packages that simulate ...
XYZT's user avatar
  • 173
1 vote
1 answer
712 views

Relationship between temperature of nebula and size of star

I was wondering, in the process of star formation, does the temperature of the nebula that produces a star play a role in the size of that star? I mean, it's only logical that the size would depend on ...
L.R.'s user avatar
  • 704
4 votes
1 answer
639 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 ...
Marcus Andresus's user avatar
19 votes
2 answers
2k 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 ...
HDE 226868's user avatar
  • 36.6k
8 votes
2 answers
889 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 ...
stevenvh's user avatar
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