Questions tagged [nebula]

A collection of ionized gases and dust in interstellar space

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6
votes
1answer
2k views

Why are O III lines so prominent in the spectra of emission nebulae when the amount of oxygen relative to hydrogen is a million times smaller?

Looking at spectra of emission nebulae like the Lagoon Nebula, the $[\text{O III}]$ lines are prominent in intensity. However, the abundance of oxygen is minuscule compared to hydrogen. How then are ...
0
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1answer
683 views

Is the galaxy made of a nebula or the solar system?

My book says on the topic 'Formation of stars' that a galaxy starts forming by the accumulation of hydrogen gas in the form of very large clouds called nebulae. Then local lumps of gas are formed. ...
9
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2answers
477 views

Is Barnard 68 the only cloud so close to us that there are no stars between us and it?

Regarding molecular clouds / absorption nebulae / Bok globules / obscuring clouds, (I'm not sure if there's one generic term encompassing all those and any similar obscuring clouds - I just used "...
14
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1answer
1k views

What are the large round dark "holes" in this NASA Hubble image of the Crab Nebula?

I came across this image of the Crab Nebula taken from NASA Hubble telescope. What are the large round "holes" and how are they formed?
3
votes
1answer
253 views

What are the dark spots in this Hubble image of the Crab Nebula?

I recently ran into this NASA Hubble image of the Crab Nebula in this article talking about its core. What I am interested to know though is: what are these round dark spots appearing in the image (...
2
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1answer
676 views

Did we discover how nebulae hold their shapes?

As you know, nebulae such as the Eagle Nebula, the Cat's Eye Nebula, and the Pillars of Creation, have extraordinary shapes. But have we discovered why that is so? I've tried researching it myself ...
2
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1answer
363 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 ...
4
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1answer
196 views

How long do hot X-ray sources last?

Some X-ray sources in nebulae are caused by hot materials in the millions of degrees that formed in supernovae. What's the cooling rate of this stuff? How long does it stay this hot? If we would take ...
3
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2answers
233 views

How do I see more than just points in the sky?

I just bought a new telescope with these specifications: Aperture: 203 mm Focal Length: 1200 mm F/ratio: f/5.9 I usually use a 28 mm eyepiece, giving me about 42.5x magnification, but I also have a ...
1
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2answers
78 views

What's the proper terminology for nebula clouds?

I'm writing a research paper over outer space (yeah, yeah, broad topic) and I'm wondering what the proper terminology for nebula clouds is. This is an excerpt from my paper showing how I'm going to ...
2
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2answers
311 views

How useful are filters for spotting nebulae?

Recently I've been trying to spot a couple of nebulae, IC59 and IC1318. The skies at the site are modestly dark (4.5 on the Bortle scale), I'm using an 8" scope, and I've slowly scanned around the ...
3
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5answers
3k 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 ...
5
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1answer
314 views

Why does hydrogen ionization happen in HII regions?

Why does hydrogen ionization happen in HII regions? Why is the hydrogen there ionized?
3
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0answers
41 views

What are the implications if the Sun was formed in a warm nebula?

Molecular oxygen O2 has been found on comet 67P/C-G in a ratio of 3.8% to water, which is much higher than expected. An explanation proposed is that the Solar System formed from a molecular cloud ...
1
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1answer
52 views

What is meant by "short lived" in the duration of a planetary nebula?

In this wikipedia article, it describes planetary nebula as "short-lived," but I'm not sure in relation to what? This could mean billions of years in some contexts. How long is short-lived? Bonus ...
4
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1answer
70 views

How do proto-planetary nebulae gain momentum?

currently I am curious about proto-planetary nebulae. At first I was curious about how planets spin but I read in a couple of articles that they got their spin from when they were in a proto-planetary ...
4
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2answers
536 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, ...
0
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1answer
79 views

How can I find out which known stars lie within or close to M8

I'm looking for a way to find stars within a certain region of space, the Lagoona Nebula in this case, based on what we currently know. Are there some databases that allow you to make such queries? ...
8
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1answer
293 views

Why is the Boomerang Nebula colder than the CMB?

An earlier answer on temperature mentioned that the temp of the Cosmic Microwave Background (CMB) is $2.4\,{\rm K}$ and the temp of the Boomerang nebula as ${\rm 1\,K}$. How did the nebula cool faster ...
1
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1answer
664 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 ...
2
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3answers
9k views

How can I see a nebula?

I've recently been seeing a bunch of pictures of nebulae and I'm just fascinated by their beauty and complexity. Is there any kind of telescope that would make it possible to view it from here on ...
25
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3answers
3k views

Why is the Eagle Nebula so "static"?

This, of course, is a newbie question, as I am nothing more than a hobbyist. But I was quite surprised to see the recently-released "before and after" pictures of the so-called "Pillars of Creation" ...
3
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4answers
2k views

Do heavier elements breakdown during supernova?

Heavier elements like gold, uranium etc. are formed at the end of a star's life. As the star explodes into a supernova, it gives rise to nebula which is the birthplace of new stars. But as the star ...
20
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2answers
1k 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 ...
8
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3answers
764 views

Are nebulae only visible from a distance?

There's plenty of data about the density of nebulae, and obviously they're pretty thin. This is space, after all, and these things are really, really big. But I'm wondering about the practical ...
29
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2answers
25k views

How many stars and galaxies can be seen by the naked eye?

How many of the luminous dots that we see naked are galaxies and not stars from our galaxy? I imagine that the majority of the luminous points that we see naked eye during the night, are actually ...
5
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1answer
104 views

Why is there billowing dust in nebulae?

Why do some nebulae look like the billowing clouds? Wouldn't that require something like a viscosity in empty space?

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