Questions tagged [star]
Questions regarding large spheres of plasma undergoing fusion.
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0answers
20 views
Star moving in the sky [duplicate]
Tonight I saw a moving star!!! I asked my friends to come and see!!! They both confirmed that it is moving!!!
It moves sometimes fast, sometimes slow in different directios but very short distance.it ...
1
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1answer
26 views
Eddington luminosity in various plasmas
So I know that the Eddington luminosity is given by:
$L_{Eddington} = 4\pi GMc/\kappa$.
I want to calculate this luminosity for a plasma of purely ionized helium, as well as for an electron-...
5
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3answers
134 views
Can a star fall in a super massive black hole without getting destroyed?
This is the first of many similar questions I have to build up to a specific question or scenario that I want to explore and find an answer to.
0
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0answers
19 views
How does the BRITE satellites compare to Kepler and TESS satellites?
I may be biased, however, there is not much information out there about the BRITE constellation as there is about the satellites Kepler and TESS.
I would appreciate if someone could tell me how the ...
5
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2answers
90 views
Why does the sun have a convection layer and a radiation layer?
Why is the outer section of the sun convective but the inner section stable and only radiative? They are both made up of the same kind of matter, both heated by the core.
2
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0answers
76 views
Is there a database of all known star names/identifiers?
I am looking for a list of all known identifiers used for stars. I'm not sure on the terminology. While I do want the "proper names", I also want whatever identifier is used for each star detected, ...
0
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1answer
46 views
Is there a theoretical minimum mass main sequence star that can become a red giant?
Wikipedia's Red Giant page says they range in mass from 0.3 to 0.8 solar masses. Which corresponds to an initial mass of a bit less than 1 solar mass, about 0.8 or so, if I was to estimate and a few ...
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0answers
22 views
Fast moving object like stars in the sky some time two in row but not moving in a straight line [duplicate]
I saw a fast moving object like a star in the sky moving but not in straight line. The brightness of it is like the yellowish normal lights in our streets but not as the colour of the twinkling stars
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2answers
68 views
Are red giants stationary or do they move? [closed]
A friend and I are having a friendly chat about this. They are stars so I'm claiming they still move in orbit.
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2answers
129 views
Why does star formation cease?
The universe is expected to have a time when star formation slowly ceases. However, this seems bizarre as there is always an abundant amount of matter in the Universe. Massive amounts of hydrogen ...
3
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1answer
77 views
Do astronomers have any idea what percentage of our galaxy’s stars move in retrograde orbits?
I recently noticed that none of the planets in our solar system orbit the Sun in a retrograde direction. This is likely because they formed moving in the same direction as the planetary disk did in ...
1
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3answers
50 views
Are white dwarfs the ones always absorbing mass from a companion?
It seems to me every time I see stellar remnant binary systems where there is a white dwarf and another star or something, it appears that the white dwarf always pulls mass from the star.
What if the ...
2
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3answers
135 views
Can Earth be ejected out of the solar system this way?
I found this image of what maybe a model of our solar system. Without a credible source I'm not sure I am looking at a star or black hole that comes close to our solar system and how it could throw ...
1
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1answer
70 views
Is it possible that in the Local Interstellar Cloud there are undetected stars?
The Local Interstellar Cloud is supposed to be around 30 light years large. Is it possible that in this region there are stars which are undetected? I would have thought that it wasn't possible, but ...
1
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1answer
80 views
When a rogue brown dwarf star hits a white dwarf star, will the collision at most cause a nova? [closed]
When a rogue brown dwarf star hits a white dwarf star, will the collision at most cause a nova?
Or can the explosion be heavier?
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0answers
49 views
Could you tell me this constellation name? [closed]
Hi Everyone please check this pictures could you tell me this constellation name ?
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3answers
107 views
Stars located outside of a galaxy
How common or rare is it to find stars outside of a galaxy? Can such a star still have planets that contain life? Recently, I think that I heard of a star with a planet that entered our Galaxy. Did ...
11
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3answers
982 views
Beta Andromedae (Mirach) and distances mentioned in original Cosmos series from 1980
In one of the episodes from Carl Sagan's show Cosmos he explains that Beta Andromedae is the second brightest star in the constellation Andromeda, and is 75 light years away. The link to the video is ...
5
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1answer
119 views
Are brown dwarfs which dont sustain any fusion considered stars?
I was reading about the coolest stars , and surprised to find about stars with a surface temperature lower than a candle, like 2MASS 0939-2448 A/B, of about 100 celsius like CFBDSIR 1458+10B and even ...
8
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1answer
165 views
What's the white glow around this star?
A few days ago, I took a photo of the night sky in the mountains of Georgia with my DSLR. There, I noticed that one single star (in the center of the part of the photo that I added below) looks very ...
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1answer
49 views
If the axis of the Earth was through Greenland, what would the north celestial pole be? [closed]
If the axis of the Earth was through Greenland, what would the north celestial pole be?
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0answers
43 views
Regarding the VizierR catalogue
I want to build a Machine Learning model to approximate effective temperatures of stars based on their B-V index but there aren't that many catalogues that include that. I came across the Vizier ...
5
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1answer
47 views
How many horizontal branch stars are within 2 kpc of the sun?
For my research purposes, I am wondering how many horizontal branch (HB) stars are within 2 kpc of the sun? I tried to find some with the Gaia DR2 data with a magnitude cut that leaves HB stars out ...
5
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3answers
171 views
How do we know distant stars still exist
The Pleiades are 450 light years away. Thus when we see the twinkle in the night sky the light that hits our retina emanates from the year 1569 or so. On that proviso; how can we be sure that the star ...
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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 ...
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0answers
35 views
Geographical Substellar position calculation from RA/DEC
I was trying to help my son with a project and thought it shouldn't be hard but turned out I'm not as smart as I thought I was.
His project is about celestial navigation. The first step is, given the ...
3
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1answer
124 views
Is it possible for stars not to rotate?
I'm just curious about that the existence of non-rotating stars. Is it physically possible for a star not to rotate at all? Does magnetic braking eventually stop the stellar rotation?
2
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1answer
45 views
How long does it take a star to transition from main sequence to red giant?
I have read that it takes billions of years for stars of approximately the size of the Sun to get through the main sequence, after which it will enter the red giant phase. When that happens, how long ...
1
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1answer
54 views
Hubble Space Telescope (HST) observing modes
I have been reading some literature on using the HST to take spectra of exoplanet atmospheres when exoplanets transit in front of their stars. The literature mention two modes of observations, '...
1
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1answer
72 views
Why do most of the myths behind constellations originate from Greek? [closed]
Why do most of the myths regarding constellations happen to have begun from Greek civilization? Why not other civilizations?
Most people who lived in the past era probably observed star patterns in ...
0
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1answer
38 views
Possibility of certain conditions on a planet [closed]
I want to know if there can be any planet that can fulfill the following conditions and if any planet has been observed with such characteristics:
The planet must not be tidally locked.
The day-night ...
4
votes
2answers
91 views
How to Distinguish between Temperature and Doppler effect using Black-body radiation?
I understand that the radiation of a body can be described using the curve for black-body radiation. In the sense that a hotter body will be blue shifted and a cooler body will be red shifted.
The ...
26
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2answers
3k views
Are we really star-stuff from the interior of collapsing stars?
Carl Sagan has said several times that we are "star-stuff".
One instance can be found in Good Reads' Carl Sagan > Quotes > Quotable Quote:
The nitrogen in our DNA, the calcium in our teeth, the ...
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0answers
44 views
Can you go blind if you look at the sunrise and sunset? [duplicate]
Everyine knows its dangerous to look directly at the sun, but can you look safely at sunrises and sunsets without going blind? Because the uv radiaton and the light is much weaker. Or is it still very ...
0
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1answer
290 views
Why are blue stars the hottest? [duplicate]
I know that blue stars are the hottest and youngest (according to Universe Today). But what makes them blue, instead of other colors like purple?
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0answers
34 views
Strength of core-envelope coupling in stars
For a star with a given Zero-Age Main Sequence (ZAMS) mass, as a function of metallicity how strongly is the star's core coupled to its envelope?
I understand that the core-envelope boundary is only (...
7
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1answer
164 views
Is it possible to predict a supernova with years or decades of advanced notice?
I know star phenomena like solar flares can (at some degree) be predicted:
https://www.dailymail.co.uk/sciencetech/article-5371481/Scientists-predict-solar-flares.html
Question: Is there any ...
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0answers
58 views
Can someone please tell me what the very bright star is that I see throughout the evening in the northern sky? [closed]
I'm located in NYC. I know it's not a planet, although it is very spherical and looks like one. Perhaps it's a satellite, because it doesn't move much and I don't recall ever seeing a star that ...
5
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1answer
49 views
Activity of M dwarf stars
Why are M dwarf stars the most active (in terms of starspots and faculae) of all stars?
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1answer
73 views
Locate planets and stars for beginners
I am a beginner in astronomy. In fact, I just bought my first refractor telescope with 60 mm aperture and 600 focal lengths with 4mm, 12.5mm and 20 mm eyepiece and 3x barlow.
Could I get info on ...
6
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1answer
59 views
Is there any star recognition framework/library available?
Being a daytime software engineer and a sparetime photographer, I was looking for a nice DIY project for the next weeks. I finally decided to build a star tracker with a camera mount, so that I can ...
5
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1answer
73 views
South-eastern sky above the tree line just now, NE Cape Cod, I saw a very bright, twinkling “star”
I live in New England, Cape Cod to be exact.
I saw a very bright, twinkling object. I watched it for several minutes and it never moved. It was in the east just above the tree line, what might it be?...
2
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2answers
194 views
What fraction of starlight, seen from Earth, is actually reflected light?
Thanks to reflected starlight, many planets and comets in the Solar System have been visible to humans since long before the development of modern astronomy.
Some of the starlight from outside the ...
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0answers
67 views
Celestron NexStar 130 SLT Computerized Telescope GoTo Not Accurate
I am trying to use a Celestron NexStar 130 SLT Computerized Telescope, but I am not able to use the GoTo function.
I do the three start alignment, it confirms matches,
I make sure the level is ...
0
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1answer
81 views
What area of Proxima Centauri would need to be occluded for the effect to be observable on Earth?
One of ideas of how Breakthrough Starshot could communicate data from Proxima Centauri is to have a massive swarm of the solar sail powered craft to pivot (with their sails) synchronously, taking ...
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4answers
3k views
Is parallax a “technique to measure the star distances” or a “tiny shift in star's position”?
I am not completely sure whether the Parallax is a "technique to measure the star distances" or a "tiny shift in star's position"?
The a book says two points about Parallax:
Astronomers have ...
2
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1answer
89 views
Information on the star at the centre of the Helix “Eye Of God” Nebula
Can someone please tell me what the mass (or size) of the star at the center of the Helix Nebula is, and how much larger it is than our own star (we call the Sun or Sol). Also, what is the name of ...
3
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2answers
156 views
Why is Proxima Centauri called Proxima Centauri?
It seems very logical, to call the star, closest to earth, "Proxima" ("Proximus" is Latin for "close" and the word for star, "stella", is feminin, hence "Proxima"), but there's one thing I don't ...
3
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2answers
143 views
Why is the metallicity of elliptical galaxies low?
As far as I understand, metallicities of old stars are usually low and those of new stars are usually high.
If elliptical galaxies form after merger of galaxies, then surely that means the elliptical ...
3
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2answers
112 views
Why don't we see purple stars
I know that we don't see green stars because in blackbody radiation star doesn't produce one spectrum.
The stars that have peaks in the green spectrum produce other spectrum in nearly same amout. ...
