Questions tagged [star]
Questions regarding large spheres of plasma undergoing fusion.
744
questions
2
votes
2answers
51 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 ...
0
votes
0answers
32 views
Henyey method for interior parts of the star
Does there exist a code that implements Henyey method for interior parts of the star?
1
vote
0answers
43 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 ...
0
votes
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 ...
-1
votes
0answers
48 views
Star and Galaxy Visualization [closed]
Is it possible to visualize star and galaxy at the same time in our minds?
Suppose you think of a star, you made a picture of it and then you create a picture of a galaxy in your mind. You must have ...
4
votes
1answer
134 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
votes
1answer
144 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
votes
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 ...
5
votes
0answers
101 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
votes
0answers
43 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. ...
3
votes
1answer
109 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 ...
0
votes
0answers
45 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 ...
0
votes
0answers
55 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
106 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 ...
0
votes
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
votes
1answer
37 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. ...
0
votes
0answers
39 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.
2
votes
0answers
54 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 ...
4
votes
1answer
104 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 ...
0
votes
2answers
72 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
votes
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 ...
0
votes
0answers
38 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/...
1
vote
0answers
30 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
2
votes
1answer
44 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
votes
1answer
29 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
votes
2answers
93 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
votes
1answer
54 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
votes
0answers
81 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
votes
0answers
331 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 ...
6
votes
1answer
90 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
151 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
98 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
77 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 ...
2
votes
0answers
21 views
Freefall timescale for a Jeans-unstable hydrogen cloud of mass M
I'm working on a project (personal, not academic) that involves calculating the collapse timescales for protostars which will end up becoming stars of varying given masses. I'm treating the pre-main ...
13
votes
5answers
2k views
What are the minimum element requirements for a star?
What elements would be essential for a star to exist?
From what I understand our sun is made of mostly hydrogen and helium and most stars have small amounts of heavier elements like carbon, nitrogen,...
7
votes
2answers
271 views
If a star were travelling at 99% of the speed of light, directly at Earth would we see it?
Stars being flung from black holes in the news made me question if something were heading directly for us at the speed of light, would we even know?
Update: Since it's impossible for a star to travel ...
1
vote
1answer
72 views
Could S5-HVS1 conceivably still hold on to any planets?
If the star (S5-HVS1) has been accelerated to 1,700 km/s by a close encounter with the super massive black hole at the centre of our galaxy (Sagittarius A*) what would happen to any planets orbiting ...
1
vote
1answer
36 views
How can I check if we can observe a certain star (given its equatorial coordinates) from a certain location on Earth (given its DMS coordinates)?
I am given the equatorial coordinates of a star (e.g. Sirius has RA: 6h45m8.9s and Dec = -16°42'52.1"). Now my question is: can we observe this star from a specific location on Earth (e.g. from ...
1
vote
2answers
52 views
Corresponding BV Value to a Hertzsprung–Russell
I have an example BV value from an astronomical catalog of 1.04 (33 Psc, HD Catalog 28).
Given only the number 1.04, can that be charted on the HR, or do I need the individual components of the value ...
2
votes
1answer
54 views
How much does the stellar radius change if seen through different filters?
I know that the radius of a star should be different depending on the filter being used to do the observation. That is, the bluer the filter, the smaller the measured stellar radius. I know this ...
9
votes
2answers
192 views
Could a star closely orbit a black hole long enough for the star to have lost 0.5B+ years to time dilation?
I was wondering how stable a close star-black hole system could plausibly be, and thus how much time a star could plausibly miss out on (from an outside observer's perspective) due to being in an ...
2
votes
2answers
146 views
Can a dying, swelling, star be rejuvinated by enveloping orbiting gas giants?
Many hot jupiter type exoplanets have been found, orbiting near their parent stars.
At the end of a stars life, they swell up and sometimes envelop closely orbiting bodies.
Combine these effects and ...
0
votes
1answer
136 views
Proxima as Supernova [closed]
Follow this question. Let's say Proxima Centauri explodes as a Supernova (I know, it CANNOT explode as supernova, let's say it can. I know, it should had exploded more than 4 years ago, let's assume ...
2
votes
2answers
128 views
Will it be dangerous when close stars become Red Giants?
What will happen if close stars like Sirius A or Procyon_A become red giants? Is it dangerous for the Earth and life on it?
If for Sirius A we still have 500-800 million years, but Procyon A might ...
5
votes
1answer
37 views
Are warm circumstellar debris disks still able to be detected at sub-millimeter wavelengths?
At these wavelengths a survey is more sensitive to detecting relatively cool disks (T<100k), but would a telescope operating in the sub-millimeter be less sensitive to warm debris disk than say, a ...
2
votes
2answers
43 views
What does the opacity of a molecular transition mean?
In particular, what does it mean when a line (e.g, emission line in stellar wind) is optically thick or thin. I know what an optically think/thick medium is, but how does this concept compare to ...
2
votes
0answers
52 views
Spectral Class Breakdown
Where can I get a more detailed breakdown of Spectral Classes. Wikipedia only has it at Letter level rather than sublevel.
For example, https://en.wikipedia.org/wiki/Stellar_classification has B ...
0
votes
1answer
80 views
Estimating a star's radius, temperature, and luminosity based on its mass
(See updated figure and description below.)
I've been trying to generate ballpark estimates for the radius, temperature and luminosity of stars in the main sequence based solely on their masses (...
5
votes
1answer
125 views
Why is a giant planet around a tiny star unusual when binary stars are normal?
Inspired by this BBC article and the corresponding journal article about the M dwarf star GJ 3512.
The Jupiter-like world is unusually large compared with its host star, contradicting a widely held ...
3
votes
0answers
92 views
Can someone calculate the age of the KOI-4878 star?
The star’s low metallicity and fairly high space velocity suggest that KOI-4878 is older than the Sun.
But I don't know how to calculate an estimation for the age.
KOI-4878 data on Simbad
