Questions tagged [nebula]
A collection of ionized gases and dust in interstellar space
103 questions
5
votes
0
answers
87
views
Why does the core-mass luminosity relation work?
Why is luminosity of a star with degenerate core and He or H shell burning (RG, AGB or between Post-AGB and PN phase) given solely by the core mass? I understand that the relation is a stable result ...
- 1,074
7
votes
1
answer
461
views
Why is said that H-alpha emission lines are stronger than the other of the Balmer series?
H-alpha lines are usually the ones you see when observing most nebulae.
If you search why is that, why are H-alpha lines more visible than H-beta, H-gamma or H-delta, the usual answer is that H-alpha ...
- 716
1
vote
0
answers
39
views
How rare are nebulae which emit H-Beta/H-Gamma/H-Delta? (Balmer series) [duplicate]
Most of the visible light emission nebulae have a lot H-alpha emissions, and because of that appear red.
But why are other Balmer emissions much rarer? Do they need a hotter environment which is ...
- 716
0
votes
0
answers
40
views
Star forming regions
Some star forming regions, like Bok globules (which contain stars that still haven't dispersed their molecular hydrogen and cosmic dust shell) appear dark compared to the rest of the H II in which ...
- 716
1
vote
1
answer
121
views
Why does infrared pass through clouds of gas and dust with minimal extinction?
Why do we use Infrared to view through clouds of gas and dust in space? I understand that it is because it can pass through without being absorbed, but why is this? My thinking is that it is because ...
- 1,097
1
vote
1
answer
93
views
What was the first nebulae of the first class?
On Wikipedia, it describes the Tarantula nebula as
the second of the "Nebulae of the First Class",
Wikipedia says that a Nebulae of the First Class is a Nebula with no other stars visible ...
- 1,097
0
votes
2
answers
1k
views
Why does Helix Nebula look like an eye?
The infrared lights, the material clumps that radiate and the whole view resembling a celestial firework or giant eye
- 53
1
vote
0
answers
91
views
What is Helix Nebula made up of?
The Helix is a planetary nebula, the glowing gaseous envelope expelled by a dying, sun-like star. Helix nebula consists of two gaseous disks, how they are formed or which material is present in it.
- 53
1
vote
1
answer
102
views
Can you identify the source of this image of the Pacman Nebula (NGC 281)?
Months ago I downloaded this glorious image of the Pacman Nebula (NGC 281) in Cassiopeia. I have not been able to identify the source of the image (e.g., Hubble, James Webb Space Telescope, etc.) and ...
- 205
7
votes
3
answers
3k
views
Distance of the Crab nebula and the speed of light
I am watching a youtube video that says that, there is plenty of historic records that shows that the star, that turned into the Crab nebula, blew up in 1054. According to the video, it is located ...
- 173
3
votes
1
answer
67
views
Is it possible to detect lyman alpha blobs (LABs) with the lyman-break method?
LABs are luminous extended nebulae of hydrogen gas in the early universe (z ≥ 3) found in overdensities of LAEs (lyman-alpha emitters) and LBGs (lyman-break galaxies). I was wondering if LABs could be ...
- 61
14
votes
1
answer
2k
views
Could it be possible to detect planets from stars that went supernova through the resulting nebula shape?
It ocurred me, if a star with at least one planetary companion undergoes a nova or supernova, we shoud expect the debris to be deflected to some degree, on exit. To ilustrate it, first let's take the ...
- 1,201
3
votes
1
answer
1k
views
Are these images of the same nebula?
This image from the Spitzer telescope is supposedly of the Orion nebula.
But this image from the Chandra telescope also claims to be of the Orion nebula.
I have been unable to confirm either of these ...
- 648
1
vote
0
answers
165
views
Mass range of a sub-brown dwarf
Sub-brown dwarfs are celestial object that have planetary mass or are termed "Planetary mass object/planemos". They do not lie in the range 13-80 MJ that defines "normal" brown ...
user47732
7
votes
2
answers
1k
views
What kind of nebula was the Sun formed from?
I was just wondering what type of nebula did the Sun form from because mainly there are 5 categories: emission nebulae, reflection nebulae, dark nebulae, planetary nebulae, and supernova remnants, so ...
user47732
2
votes
0
answers
116
views
How tall are the pillars of creation? (angular and physical) How bright are they? [duplicate]
NASA's October 19, 2022 NASA’s Webb Takes Star-Filled Portrait of Pillars of Creation shows a sparkly and beautiful infrared image of the Astronomical elephant trunks known as the Pillars of Creation.
...
- 30.7k
5
votes
1
answer
67
views
How to interpret illumination in "pulsar cannonball" image
This beautiful image (from APOD) looks like the trail of the ejected pulsar is illuminating a ball of gas and dust. My eye sees patches of light and shadow, but sometimes images can be deceptive. What ...
- 3,974
11
votes
1
answer
2k
views
What is the bright orange star?
After reading this NASA article on Tarantula's Nebula of this image:
What is the really bright orange star in the center or upper-left of the young blue stars? The second link further provides ...
- 2,115
29
votes
2
answers
6k
views
When stars explode after running out of fuel, why are new stars born from the remnants?
I'm not a physicist or have a very good physics background but I've often wondered why there are new stars that are born in the nebula which was created after the parent star has exploded. As I ...
- 393
22
votes
1
answer
2k
views
What causes the sharp if irregular boundary line in the "Cosmic Cliffs" JWST Carina image?
In this recently released JWST image:
we can see a relatively sharp, if irregular, boundary line between a region appearing mostly bluish and a region appearing mostly reddish or orange (understood ...
- 863
1
vote
1
answer
108
views
How to locate M13, Ring Nebula?
This is a bit last minute. I'm leaving shortly to go camping and expect to have dark skies. I watched NASA What's Up June 2020 which suggested checking out M13 (for which it gave pretty good ...
- 395
2
votes
1
answer
109
views
Do supernova remnant nebula re-collapse into a star?
We know that nebula sometimes collapse into stars. The particles are attracted to the joint gravitational center of the whole nebula.
One type of nebula is a supernova remnant nebula. Unlike a normal ...
- 624
-1
votes
1
answer
214
views
Wouldn't the 1054 supernova have temporarily enlightened the Earth like the Sun?
The peak luminosity of all type Ia supernovae is 1.60×1036 Watts. If we see a star go supernova from earth, and we observe its intensity to be 1.0 W/m2. The intensity of the Sun is about 6.33x107 W/m2....
- 1
2
votes
1
answer
81
views
Is it possible to take the same images in HST palette as the optic telescope but with radio telescope?
Is it possible to detect signal from SII, H$\alpha$, OIII using radio telescope and make the similar images as optic telescope? If no, can we use the different elements to take signal?
What minimal ...
- 266
4
votes
2
answers
145
views
Are older main-sequence stars found in or near molecular clouds?
From what I have read as molecular clouds are the birth place of stars, their population as you would assume are young stars or stellar remnants but so far I have not found out if there are main-...
- 141
3
votes
2
answers
365
views
Why is the Emissivity of emission lines in unit erg.s-1.cm3?
The python package PyNeb could calculate the 'Emissivity' of an emission line at given electron temperature and density in unit "erg.s-1.cm3". But I don't know why Emissivity should in such ...
- 73
0
votes
1
answer
779
views
Can you calculate the radius of a galaxy from Angular Size?
Is there a formula for calculating the size of a galaxy or even a nebula if you have the Angular Size. For example, M31 has an angular size of 199.53 70.79 35 (Opt) D
M31 should be 200,000 light ...
- 1,341
25
votes
4
answers
3k
views
How else can a star form, other than gravitational collapse?
I read this paragraph on the Sun's page on Wikipedia:
[The Sun] formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most ...
- 251
1
vote
0
answers
106
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?
- 17.7k
7
votes
2
answers
132
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 ...
- 511
13
votes
3
answers
2k
views
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 ...
- 624
3
votes
1
answer
300
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 ...
- 31
1
vote
1
answer
122
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 ...
- 1,306
0
votes
1
answer
263
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)
19
votes
3
answers
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 ...
- 193
0
votes
1
answer
250
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). ...
- 3
9
votes
1
answer
291
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 ...
- 333
4
votes
1
answer
71
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, ...
- 6,733
3
votes
1
answer
220
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) ...
3
votes
1
answer
161
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? ...
- 31
16
votes
2
answers
3k
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 ...
- 163
3
votes
0
answers
88
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 ...
- 5,657
4
votes
0
answers
85
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 ...
- 523
4
votes
1
answer
204
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 ...
- 183
2
votes
0
answers
55
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 ...
- 5,657
2
votes
0
answers
39
views
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 ...
- 1,559
3
votes
2
answers
564
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 ...
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 ...
- 31
3
votes
0
answers
165
views
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, ...
- 241
4
votes
1
answer
240
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
- 103