Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

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7
votes
1answer
580 views

What is the most appropriate way to estimate the helium composition of a star?

Say we have to estimate the helium content in Proxima Centauri. We begin by calculating the content of helium in the Sun (source): $24.85$% of $2.10^{30}$ kg. Mostly all the energy is generated due ...
6
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2answers
778 views

What is the furthest star for which we can measure the diameter?

If a star is close enough that we can measure its parallax and that it doesn't appear point-like, then we can deduce its diameter. Can we measure the diameter of all the stars for which we can measure ...
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0answers
29 views

I saw something move in the sky and i am not sure what it was :( [duplicate]

I saw a little light from between two stars(it had the same size as the star) moving in a straight line and then it went from one side of the moon and came out from the other end(i am not sure but i ...
5
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1answer
119 views

How do K, F, A and B stars die?

I know that M (red dwarf) main-sequence stars slowly fade to white dwarf stars, and that G (yellow dwarf) main-sequence stars become red giants and then shed their outer layers in a planetary nebula ...
0
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1answer
72 views

What is the precession of the star S62? [closed]

What is the angle of precession of the star S62 orbiting the Milky Way supermassive black hole?
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0answers
30 views

What were the moving lights in the sky tonight? [duplicate]

Tonight we saw moving lights in the sky south east of Orion's belt. Anyone any ideas what they were? About 20 of them all going in the same direction east.
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0answers
51 views

Alien “train” in night sky any one else seen these [duplicate]

on march 1 2020 my sister and I were out about 530am and near the big dipper stars were moving one the two one then two (* ** * **) for about 15 minutes this continues like a train moving they seem to ...
2
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1answer
68 views

how to calculate distance between galaxies in the distant past

for example, assume there is a high redshift galaxy called "A" with z=6, so how to calculate the distance between us and another galaxy B when the light left the galaxy A? For example, say B has a ...
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0answers
31 views

Yesterday I saw multiple moving objects in my telescope when i was looking for M31. Do you have any idea what it could be? [duplicate]

Yesterday, when I was looking at the Andromeda Galaxy in my telescope. I saw three star like objects, moving across the sky. I followed them to see what is was, though i still don't know. They where ...
2
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0answers
36 views

Stars moving in line and some moves around [duplicate]

I am from South Africa this morning around 05:00 I saw 7 to 9 stars moving in line and some moves around. What cause that to happen. Because I have never saw something like that before.
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0answers
67 views

What is the dielectric constant of a star?

1) What is the dielectric constant of a star, especially its corona? Is it of order 1 or is it quite large? 2) How much do "impurities" (elements other than H and He) affect the dielectric constant?
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1answer
68 views

Stellar age determination - code

I'm trying to determine the age of some stars. I have many parameters that characterize these stars: $T_{eff}$ ,log ${g}$ ,$[Fe/H]$, $V$... I've tried to use the isochrones package but so far no ...
2
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1answer
75 views

Estimating star temperature

I have an assignment, where I'm supposed to estimate the temperature of a star in at least two different ways, and determine which of the approaches gives the most reliable estimate. All that is given ...
0
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1answer
47 views

Q: star scaling calculation

If in our neighborhood of the Milky Way, the typical spacing between stars is 1 parsec, and the relative velocities between neighboring stars are of order 20 km/sec, what would the spacing between ...
2
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2answers
366 views

What planets or exoplanets orbit the Sun’s elder twin HIP 102152?

Has anyone done any research on the planets that orbit the HIP102152? Since that star is similar to ours and older, I postulate that it’s likely those planets are most worthwhile searching for ...
2
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2answers
209 views

What star is the closest to Betelgeuse?

Based on this answer, I should be able to figure out this question, if I know the distance between Betelgeuse and its nearest neighbor. So what is Betelgeuse's nearest neighbor? I do mean the ...
1
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2answers
86 views

Why does the Gaia color-magnitude diagram have this shape?

I was looking at the visualization tools of Gaia, and tried plotting a color-magnitude diagram. On the right hand side of the image, photGMeanMag (mag) (the amount ...
2
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1answer
65 views

How can a star's rotation speed be measured?

How can a star's rotation speed be measured? If stars could be resolved, then you could use the Doppler shift to see that half of the star is bluer and the other half is redder, but stars (other ...
2
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2answers
58 views

How variable does a star have to be, to be a variable star?

Variable stars are stars whose apparent magnitude varies. But there are so many phenomena that can cause a star to be variable, that I would expect all stars to be variable. A rotating star has a ...
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0answers
38 views

Henyey method for interior parts of the star

Does there exist a code that implements Henyey method for interior parts of the star?
4
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1answer
211 views

When Betelgeuse goes supernova, will the explosion hit any neighboring stars?

There is evidence Betelgeuse might go supernova "soon". Are there any stars in the vicinity of Betelgeuse that are close enough that they will be hit by the explosion of this supernova? What would be ...
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0answers
55 views

I saw this ball of light moving across the sky [duplicate]

As I stated in the title, I saw this ball of light moving across the sky. It wasn't moving fast, but it wasn't moving slow. So, I was sitting my dad's car when I looked through the windshield and at ...
4
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1answer
264 views

How much more life could the Sun acquire via star lifting?

It has been proposed before that we could use this technique to remove hydrogen from the Sun to lower it's rate of fusion and extend it's life, so it doesn't fry our planet. I am wondering how much ...
4
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1answer
301 views

Distance to Proxima Centauri (Gaia VS New Horizons parallax program)

The current best parallax measurement for the nearest star to the Solar System, Proxima Centauri, has been given by the European Space Agency's Gaia mission. This is $768.5004\; \pm \; 0.2030 \; mas$ (...
30
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3answers
5k views

What is this web on the surface of the Sun?

I was going through my Social Media Feed and found the attached post too frequent. The caption reads this is the best image of our Sun. Just as an example, the Universe Today's This is the Highest ...
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0answers
120 views

Could a star have a Saturn-like ring?

Saturn's rings will never clump together, because they are within the Roche limit. Which makes me wonder if a star could have rings that are kept from clumping together due to tidal forces. Have any ...
2
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0answers
48 views

The mass of Subdwarf B progenitors in the main sequence

Note: By "progenitor", I mean "the star as it was when it was still main sequence". Please correct me if I've got the terminology wrong. Most B-type subdwarfs have mass roughly half that of the Sun. ...
2
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1answer
135 views

“Juxtapositions” of moon,stars and planets in the sky,

What are "Juxtapositions" of the Moon, stars and planets called? When the Moon, stars and planets take exactly the same position after few or many years, how to describe the positions and what is ...
1
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1answer
118 views

When exactly star Sirius shines into the queen's chamber of Great Pyramid?

I read that Great Pyramid was built to resonate with Sirius by aligning an airshaft that connected to queen's chamber. That is, the light of Sirius going through the shaft would be able to shine into ...
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0answers
161 views

Saw 8 stars moving in same direction one by one [duplicate]

I saw 8 stars moving in the same direction one by one and then at the same point they faded or you can say disappear. The speed was not too fast but not too slow either. I am more curious because ...
2
votes
1answer
139 views

Several stars in line [duplicate]

I can see several stars in the sky they can make a line come from the West south and going to East north direction at the time between 6.50 to 7.00 pm Indian time on date 13.1.20. What might these ...
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0answers
29 views

Stars moving in a row [duplicate]

Today I saw with my wife and neighbours stars are moving in a row almost 10 to 12, and after a few minutes 2-3 stars moving in different direction in a row. What could they have been?
0
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1answer
41 views

Does the orbits of stars in a binary system have a common focus, which is the center of mass of the stars?

I know that when a planet orbits a star (and assume the star is stationary because its mass is >> the mass of the planet), the orbit is an ellipse, and the star sits at one of the foci of the ellipse. ...
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0answers
41 views

I also see the line of 30 stars @today(11/jan/2020)on5:35am [duplicate]

I can't take any pic because I don't know how many light are coming.
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0answers
86 views

more than 30 moving stars [duplicate]

I am Abdul Kadhir from Kochi, Kerala, India. I, my wife and my daughter have seen today (2020-01-11) morning 5.45 AM IST a line of stars. A pair of more than 30 stars moving in a line from south to ...
5
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3answers
151 views

Is there a stellar database that indicates how long ago stars in our Galaxy formed?

There are several ways of determining the age of a star: its position in the HR diagram, the presence of a protoplanetary disk, it belonging to a cluster... When did the stars in our Galaxy form? Do ...
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2answers
109 views

What constellation is closest to the Zenith with RA=12 and Dec =47.6?

I have several options, but I do not know how to calculate which option is closest to the zenith in title. Could you please help me with this? Thank you. ...
0
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0answers
54 views

stars moving in the sky or something [duplicate]

I was out in the garden having a cigarette and was watching the shy looking at three stars for about 5 minutes. suddenly they moved in the sky and crossed paths.one has now stopped still and would ...
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0answers
48 views

Astronomical events and Celebrations

In the past people celebrated important astronomical events and some of those events are still celebrated in some cultures and traditions. For example: March/September equinox, New Moon, Winter/...
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0answers
31 views

A line of lights in sky [duplicate]

I just seen this in sky a line of stars probably satellites just wondering what they where and what they doing it was amazing never seen any like it
3
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1answer
72 views

Correlation between stellar mass and galactocentric distance

As we move away from the centre of, say, a spiral galaxy, is there a relation between the stellar mass and distance? I know the how the stellar abundance and density varies with the distance but does ...
0
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1answer
32 views

Data for spectrum of Wolf-Rayet stars

I'm looking for a way to access the data used to produce these plots for instance. These plots show the spectrum of various Wolf-Rayet stars. I found a few websites where you have some informations on ...
4
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2answers
98 views

Population density of stars within $13$ light-years of us

This item from Fox News refers to "over 600 stars that came within 13 light-years of the sun". Because of the past-tense "came", they could have meant stars that are not now within 13 light-years of ...
2
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1answer
71 views

Redshift and Velocity relation

Let us say that we have an object so its total velocity is defined as \begin{equation} v_{tot} = v_{pec} + V_{rec} \end{equation} Where \begin{equation} V_{rec} = H_0r \end{equation} and \...
2
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0answers
83 views

Can “rock stars” form from interstellar dust?

Imagine a large and massive dust cloud made of solid phase micrometeoroids, asteroids and larger planetoids, all material in it is in solid phase, and contains no hydrogen or other volatiles in gas ...
4
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0answers
332 views

Why the space is so dark even there are billions of stars and many quasars emitting light [duplicate]

In our galaxy itself, there are millions of stars, and there are many more other galaxies in our local group and billions in the observable universes. For sure they all emit a lot of light, still why ...
7
votes
1answer
127 views

Why does the convective core in an intermediate to high mass star shrink?

The image below shows the evolution of the hydrogen mass fraction profile for a 5 solar mass star in the main sequence. I would expect that the size of the convective core stays roughly constant as ...
8
votes
1answer
299 views

The colour of blue dwarf stars

The paper "M dwarfs: planet formation and long term evolution" describes blue dwarf stars, a hypothetical next-stage in the lifespan of red dwarf stars within a certain mass range, after which they ...
3
votes
2answers
114 views

Lifespan of B-type subdwarfs

According to the Extrasolar Planets Encyclopedia, the B-subdwarf Kepler-70 lost its helium envelope and became a blue-white subdwarf roughly 18.4 million years ago. (sources: archived encyclopedia ...
1
vote
1answer
172 views

Is the turn-off point of the main sequence the same as the terminal-age main sequence?

The turn-off (TO) point is one tipping point on the Hertzsprung-Russell diagram (HRD) where low-mass stars start to evolve from the main sequence (MS) toward lower temperatures. If I understand it ...

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