Questions tagged [star]
Questions regarding large spheres of plasma undergoing fusion.
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3answers
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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
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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 ...
4
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0answers
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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 ...
7
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1answer
140 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
46 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
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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
46 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
156 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 ...
16
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2answers
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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
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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
122 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
41 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
49 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
65 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
84 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 ...
27
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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 ...
1
vote
0answers
43 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 ...
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1answer
75 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
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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
votes
1answer
149 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
55 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 ...
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1answer
45 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
67 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
57 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
votes
1answer
61 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
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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
58 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
votes
1answer
80 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
85 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 ...
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2answers
130 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
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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
99 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. ...
2
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0answers
62 views
What is the total number of stars in the universe? [duplicate]
I mean a total number of stars, not the only ones that we can see.
2
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1answer
50 views
Searching for stars with a given surface temperature and an absolute magnitude?
Do you have in mind any database/sites that I can search for stars that matches a given surface temperature and an absolute magnitude?
For example, when I enter ...
4
votes
1answer
277 views
How do astronomers know if a planet is orbiting a star, or it's simply another star in the background?
For example, if astronomers photograph a "planet", which is in close proximity to a given star, then this "planet", could actually just be another "star" in the background, many light years away.
It ...
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1answer
60 views
Could population III stars develop directly into population I stars?
Hundreds of millions of years after the Big Bang, the very first stars began to form consisting of mostly hydrogen, a bit of helium, and maybe some lithium. These stars lacked any "metals" (elements ...
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2answers
73 views
What is a type la supernova? [closed]
I’ve heard about them and know that they are used as standard candles, but what exactly are they? What makes them differ from other supernovae? Also, are they only special because of their use as ...
14
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2answers
2k views
Does a star fuse helium to beryllium on the main sequence?
When a star has finished fusing all its hydrogen into helium, it will then start fusing helium into beryllium and so on and so forth up until iron.
When the star is fusing to beryllium, will the ...
3
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1answer
53 views
Is T Tauri a compulsory stage for stellar evolution?
Do all stars go from Protostar stage to T Tauri and then to Main Sequence or is T-Tauri stage only for certain stars? If only certain stars, is that those that are less than 3 solar masses which i ...
5
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3answers
287 views
Why do stars twinkle but planets don't [duplicate]
Many people say that stars twinkle because of Earth's atmosphere. However, the atmosphere is still there when we look at planets and don't see they twinkling.
Is there a clear scientific consensual ...
2
votes
1answer
55 views
Are Symbiotic and Vampire Stars the same type of star or different?
Are Vampire Stars and Symbiotic Stars the same type of star or is there a difference?
Vampire Stars siphon off hydrogen from its neighbour. According to https://www.cfa.harvard.edu/~kenyon/ss/, ...
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1answer
84 views
Light pollution and apparent magnitude of objects in solar system
Dust along the ecliptic scatters light, causing “light pollution” throughout the orbital plane of the solar system. If an object like, say, the sun's corona, had its brightness measured from above the ...
0
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1answer
136 views
Why does the sun appear 13x bigger through diffraction in Voyager 1 image from 1990, but not from Earth? [closed]
The sun in the Voyager 1 photo here from 1990 appears 13x bigger than its diameter, diffraction of course. On Earth, photographs of the sun do not make it appear 13x bigger. Why?
A description of the ...
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1answer
74 views
Are there any optical method of viewing stars without “diffraction” making them appear larger? [closed]
In the 1700s, Edmond Halley and others discovered that stars appeared larger than they are, and attributed it to diffraction in the lens of an observer (telescope, eye) and/or in the Earth's ...
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1answer
74 views
In the closest stars, can you see the stellar corona?
Stars appear larger than they are, could that be the stellar corona here around Sirius, making it appear n-times larger than the stellar body? NASA recently mapped the solar corona to extending 12 ...
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1answer
67 views
Is the orbit of Sirius B based on observation, or derived from the variation in proper motion of Sirius A?
It is common to base models on deduction rather than empirical observation. The orbit of Sirius A is easily seen as variation in proper motion. The orbit of Sirius B, has it been observed, or is it ...
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1answer
78 views
Are there any good images of Sirius B at apastron in the Sirius system?
Sirius B has a distance to Sirius A of 11 arc seconds at apastron; are there any good images of it at that point in its orbit?
3
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2answers
101 views
How does a blackhole burp?
Recently on the discovery channel I heard that a black hole burps matter out of it when it consumes more than it could process at a time. Given that even light cannot escape from a black hole, how ...
