Questions tagged [nebula]

A collection of ionized gases and dust in interstellar space

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6
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1answer
157 views

What are realistic and unrealistic values for the high energy gamma ray spectral indices of pulsar wind nebulae?

This summer, I was working on a project fitting very high energy gamma ray spectra of the Crab Nebula, a pulsar wind nebula. At energies about $\sim$1 TeV, a simple power law suffices, i.e. $\phi(E)\...
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23 views

Who gave the Pelican Nebula its name?

IC 5070 is a nebula in Cygnus that is also sometimes called the Pelican Nebula. Who gave it this name?
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2answers
87 views

Could stars be seen from inside a nebula?

Nebulae look dark against the backdrop of stars, but how opaque are they likely to be from inside? In other words, if our Solar System had drifted into the middle of, say, the Horsehead Nebula, would ...
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3answers
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Are Brown and Sub-Brown Dwarfs secretly more common than stars?

I recently heard that Red Dwarfs are the most common type of star, and low-mass Red Dwarfs are the most common type of Red Dwarf. This seems to imply a generic trend that the lower the mass, the more ...
3
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1answer
132 views

Can violet astronomical objects exist?

According to black-body radiation, violet stars are not possible. Even if there are 1 million Kelvin, they are blue, not violet. But are violet galaxies, nebulae, clusters etc. possible? Google found ...
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1answer
60 views

Why is there a discrepancy with calculated and given age of nebula

In the book "Horizons: exploring the universe-Cengage learning (2018)", page 206, it states that: Simple observations tell astronomers about the nature of planetary nebulae. Their angular ...
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 ...
6
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1answer
220 views

Assuming no light pollution, was "2C. 1406" ever visible to the naked eye?

Joseph Needham, in his Science and Civilisation in China Vol. III, claimed that there was an ancient record of a nova about three thousand years ago. As a result of private correspondences with a "Dr ...
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1answer
112 views

How do I design a good telescope to observe nebulae and other deep sky objects [closed]

How can I make a good telescope that is powerful enough show nebulae and other deep sky objects ? (consider low budget build)
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3answers
3k views

Why can space telescopes see through a planetary nebula?

I recently read the book "An Introduction to Planetary Nebulae" by Jason J. Nishiyama. Although I'm not an astronomy student, I could at least understand the written texts and less the ...
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1answer
31 views

What does the Reddening line represents in this U-B vs B-V plot?

The plot is from this paper (pg-8). They have also talked(in the same paper) about how central stars from galactic longitude range $20^\circ-80^\circ$ will have a very unusual Reddening line (pg-9). ...
8
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1answer
167 views

The physical processes of emission lines in cosmic nebula

I think I understand how absorption lines in cosmic bodies occur. But after reading about the emission lines in quasars I am wondering more and more about the physical processes causing the emission ...
4
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1answer
53 views

Long-lived supernova remnants?

We cannot see the supernova remnant of the star that triggered the formation of the Sun and the Solar System, as the remnant dispersed and became mixed into the interstellar medium. So I am wondering, ...
8
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1answer
288 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 ...
3
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1answer
99 views

Information on Planetary nebula formed from the death of our star the 'Sun'!

I want to know the expansion rate, composition, mass and density of hydrogen present of a Planetary nebula similar to that which will be formed after the death of our star the sun. Knowing these ...
2
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1answer
96 views

Are the bright dots in this image individual stars?

I saw this picture of M51 (Whirlpool galaxy) and noticed many, many bright dots around and in the galaxy. I have freehand-circled a few as examples. Are these individual stars (probably supergiants) ...
2
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1answer
86 views

The star that died and became the Crab Nebula and Crab Pulsar?

The supernova of this star was witnessed about 1 thousand years ago, and the star's remains are the Crab Nebula and Crab Pulsar. What is this no longer existent star called? How massive was this star? ...
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2answers
2k views

Is it possible that the Sun and all the nearby stars formed from the same nebula?

I was looking at a map of our local stellar neighborhood, and it occured to me, the stars are really close, if one compares them to the size of some nebulae. So can it be, that the Sun, Alpha Centauri ...
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0answers
55 views

Can the "haze" of a mirror telescope be quantified?

When reading Why was StDr56 discovered only now? and its answers and comments, I realized that refractor telescopes, and in particular the Dragonfly Telephoto Array are a great tool to find nebula and ...
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0answers
70 views

From what distance could the Sun's planetary nebula be seen entirely with free eye?

When collapsing to a white dwarf, a red giant Sun would emit a planetary nebula. How far from the Sun would that nebula stretch at most? Also: At about what distance could you see the planetary nebula ...
4
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1answer
131 views

Why was StDr56 discovered only now?

StDr56 is a newly discovered planetary nebula (maybe). link1 link2 It was found by amateur astronomers Marcel Drechsler and Xavier Strottner. According to the above articles, it's pretty big: With an ...
4
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1answer
195 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 ...
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0answers
40 views

How to algorithmically distinguish between different types of nebulae?

I remember that there are five types of nebulae: Planetary nebulae have not much to do with planets, but are emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red ...
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4answers
3k views

Can we see the color of nebulae?

Someone asked me this question: To see the color of the Great Nebula in Orion, how large the aperture of the telescope should be. I don’t even know whether this is possible. I understand that the ...
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2answers
131 views

Is this gas cloud or lens effect?

I was going through the zoomable image of Milky way and after zooming to this particular location, we can see a reddish area on the left side of a probably large star. Here is a screenshot I took ...
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0answers
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Are radio telescopes finding radio-dark Nebulas

Are there "dark nebula" spots in the sky for radio telescopes? By that I mean, are there portions in the sky where these telescopes do not receive any radio waves? If so, do they match ...
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2answers
511 views

Is there a Vela Nebula?

The Vela pulsar is a neutron star from a supernova that exploded 10,000 years ago. It spins 11 times a second. The Crab Nebula along with the central Crab Pulsar formed 1000 years ago. This pulsar ...
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3answers
8k 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 ...
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1answer
1k 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 ...
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Is there a known relation to patterns of star formation in a molecular cloud?

I was wondering if there was a known pattern to what mass of stars can form in a molecular cloud depending on what had formed before them? Having read that when blue giants form and go supernova in a ...
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Hydrogen Frost Line? Where, if anywhere, is it cold enough for Oort Cloud objects or rogue planets to have solid hydrogen on their surfaces?

I like the idea of Oort Cloud objects all being crusted with a thin layer of hydrogen snow, though what little information I've managed to find on the topic seems to imply that that is unlikely, ...
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1answer
136 views

Why isn't our local interstellar space colorised?

Looking at answers to this question, people seem pretty convinced that human naked eye should be able to see the colour of ionised gas/dust cloud when they are inside an emission nebula. And we know ...
4
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1answer
202 views

Whose name is Fleming 1 nebula bearing?

Fleming 1 is an unusual planetary nebula situated in the Centaurus constellation. Yet it is not clear after who it was named
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1answer
757 views

Whose name is Minkowski 92 bearing?

Minkowski 92 is a protoplanetary nebula. But after which Minkowski is it named? Same question for Minkowski's object (part of NGC 541).
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1answer
133 views

Nebula and its colors

A Nebula has bright awesome colors that include red, blue, green, orange, white, etc? They're result of excitation of electrons. Is there a clear explanation as to which color is attributed to an ...
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0answers
30 views

Nebula and its Colours [duplicate]

A Nebula boasts of Too Bright Awesome Colors that includes red, blue, green, orange, white, etc? They're result of excitation of electrons. Is there a clear explanation as in which Color is ...
9
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1answer
337 views

Will the nebula of Betelgeuse be visible to the naked eye? How bright, how large, how soon, for how long?

When Betelgeuse goes core collapse supernova it will leave a supernova remnant. Will it become visible to the naked eye? If so, in what time frame will it be visible. Will it be star like from the ...
2
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1answer
461 views

DSO in a 60mm telescope

I am thinking about buying a telescope, but here in Brazil they are very expensive and hard to find where to buy. So, the better telescope I can pay for is a Celestron Powerseeker 60AZ. My main ...
4
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1answer
102 views

How can an accretion disk form around the central star of a planetary nebula?

I was reading the 2012 paper A tidally destructed massive planet as the progenitor of the two light planets around the sdB star KIC 05807616 about the possible origin of two exoplanets that orbit a ...
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0answers
68 views

Does Nickel show up in spectra of Nova?

Does a nova, not a supernova, get hot enough that nickel is produced despite its formation by fusion being an endothermic reaction? If nickel is made, does it make it out of the star into the nebula? ...
3
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2answers
846 views

How to locate nebulas visible through AstroMaster 114 telescope without device assistance?

I will be going to the desert this month and it's my understanding that the night sky will be very dark there. I've got some practice locating the planets but I'd really like to get a look at a nebula ...
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2answers
467 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 "...
2
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2answers
841 views

Are the viewable nebulae only in our galaxy?

Where are all the nebulae located? Yes, a simple question that should be obvious but apparently is not to me. To be more explicit, how far are all these objects? Are they mostly in our galaxy? I'm ...
2
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1answer
139 views

How dark would the sun become if we traversed a Bok globule?

Bart Bok gave his name to dust clouds of 2-50 solar masses, which by their darkness may be 100 times more frequent than telescopes can detect. If the solar system traversed a Bok Globule, how dark ...
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1answer
117 views

Eagle Nebula (Pillar of Creation) destroyed?

How do they know that the pillars have been destroyed if the light will reach us in 1000 years time? The "Pillars of Creation" from the Eagle Nebula. Evidence from the Spitzer Telescope suggests ...
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1answer
262 views

What factors makes a star big in size(Physically)?Is the size of the nebula a relevant factor?

(Our sun compared to some of the known stars) I know that the star is born in a nebula.Do only a extremely gigantic nebula give rise to large-radius star or is there any other factors related?
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2answers
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Is this an actual nebula or CGI?

I'm thinking of putting a large wall paper with an astronomical motive on a wall. I found quite a number of wall papers by various vendors, but most of them are obviously computer generated images, ...
2
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1answer
117 views

Determining line ratios in planetary nebula

I know that the line strength ratio tells us how hot the electron plasma in a nebula is, and also give information about the electron densities in the nebula. But how do you compute the line ratios? ...
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0answers
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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 ...
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1answer
174 views

Is this a real photo or an art work?

I've never seen this Hubble picture, is it an artist impression? It's fascinating because there are voids apparently cause by supernovae. From the video 1 Hour of Epic Space Music: COSMOS - Volume 1 ...