Questions tagged [star]
Questions regarding large spheres of plasma undergoing fusion.
809
questions
2
votes
1answer
56 views
Is there a possibility of finding a system where a star is orbiting a planet?
Is it possible for a star to orbit a planet IF the planet is bigger than the said star?
Or is it possible even if the star is bigger than the planet and still the star is orbiting the planet?
I have ...
1
vote
1answer
96 views
What is this planet or satellite in this picture?
I took this photo in Shijiazhuang, Hebei Province, China, 38°13'N 115°18'E
(+38.23, +115.31) on the night of February 8, 2020. Here you can see a round object above the moon, and it was moving fast,...
0
votes
1answer
29 views
Relation between age and spectral type of star
Does the spectral type of a star change as it ages? Since its temperature changes, I suppose the spectral type should also change, but I'm a bit confused about this.
Also, is the spectral type ...
3
votes
1answer
47 views
Is most hydrogen in the universe in the form of plasma, atomic neutral hydrogen, ionized hydrogen, or molecular?
I have had trouble finding an answer somewhere....
Some places say most hydrogen is plasma, such as the stuff stars are made of (mostly) and the 'warm-hot intergalactic plasma'.
Other places say ...
4
votes
1answer
39 views
Alfven Radius of mainsequence stars
Is there any average value for the Alfven radius of main-sequence stars? if there are no such values, then how may I calculate it??
1
vote
0answers
36 views
How to find the temperature of a planet accounting for the atmosphere?
Recently, I started writing a program to generate star systems, and I need a formula to find the approximate surface temperature of a planet. I know of several formulas for this, for example this one ...
9
votes
2answers
1k views
Are there stars with an average density greater than the central density?
Are there likely to be stars for which the average density is greater than the density at the centre? Intuitively, I would say not, as density tends to decrease outwards, but ideally I would ...
0
votes
0answers
71 views
Which star has the lowest absolute magnitude?
I have seen many lists of stars with the most luminosity, mass, and temperature, but I have never seen one that is about absolute magnitude. So I'm wondering, which star has the lowest absolute ...
1
vote
0answers
46 views
What does the Sun “look like” below 100 MHz?
Radio2space.com's The Radio Sun says:
At very low frequencies (below 0.1 GHz) and therefore at very long wavelengths (> 3m) the solar disk appears much bigger and brighter in the center, and its ...
6
votes
3answers
154 views
Determine spectral type of star from its properties
How can I determine spectral type of star, if I know all its another properties? For Example, Rigel A has spectral type B8Ia.
Rigel has temperature 12 500 K. ...
7
votes
2answers
1k views
What color is a red dwarf star?
I read recently that a red dwarf star might actually look white. I realize there's a wide range in red dwarf surface temperature, 2,500 to 3,500 degrees K, compared to 5,778 for our Sun. Metal at ...
1
vote
1answer
73 views
How to approximate the distance at which the thin disk peaks along a given LOS from Earth for a given galactic coordinate per 1 sq deg?
The density of stars drops off exponentially from the center of the galaxy and can be approximated as follows using a cylindrical coordinate system:
$$ \rho(R, z) = \rho_0 \exp \frac{-R}{h_R} \ \exp \...
2
votes
0answers
27 views
Is the magnetic field strength of a star predictable from mass, composition, age and angular momentum alone?
This answer to Which stellar properties can we describe as “first principles” in which we can derive the rest? contains an intriguing bit:
That states that composition and mass are the two key ...
13
votes
0answers
291 views
What was the absolute limit to the possible sizes of the first stars formed from “primordial material with no metals”?
This answer to Why don't or (can't) stars be more than 325 or so times the mass of the sun? What limits their size? includes the following:
...The upper limit you refer to is for compositions similar ...
24
votes
1answer
2k views
Why don't or (can't) stars be more than 325 or so times the mass of the sun? What limits their size?
Is there a particular reason(s) why stars cannot grow as massive as they want to?
And why doesn't this limit apply to supermassive black holes?
11
votes
2answers
1k views
Which stellar properties can we describe as “first principles” in which we can derive the rest?
Mass, size, temperature, luminosity, chemical composition, the initial abundance of the molecular cloud, distance, brightness, age, and evolutionary cycle can all be used to characterize a star. A ...
3
votes
1answer
54 views
Calculate object apparent diameter by distance and radius [duplicate]
I'm trying to create a dynamic starfield for game using the HYG database. Because there are no data about the apparent size of the stars from earth, I will need to get it myself. I found a formula ...
3
votes
1answer
86 views
Are there ways to determine a star's spectral type without the spectrum itself?
Because of the lack of available data online, I am trying to find other ways to determine an exoplanet's host star's spectral type.
-2
votes
1answer
50 views
What can a star's spectrum tell us? [closed]
Stellar spectra contain both emission and absorption lines. What can these lines from a star's spectrum tell us?
3
votes
1answer
34 views
Difference in stellar abundance numbers
What is the correlation between stellar abundance by mass and by number?
Let’s take the Sun and Helium for example. This paper mentions an abundance by mass for helium as Y=0.275 and by number as A=10....
1
vote
0answers
56 views
How do I calculate the surface temperature of a star from luminosity? [duplicate]
How do I calculate the surface temperature of a star from luminosity? I've been trying to delve into speculative solar systems for a bit, and I've heard the surface temperature of a star can be ...
0
votes
0answers
50 views
XML Catalogue of Stars
two years ago I grabbed an XML star catalogue of the zodiac constellations that came in the following format:
...
1
vote
1answer
32 views
How to use spectral flux density data while using Planck's law giving spectral radiance?
I'm currently working on a fun project in my free time where I'm trying to calculate the temperature, among other things, of stars based on their spectra. Since I have essentially no prior experience ...
1
vote
1answer
39 views
Distance between objective lens and eyepiece
I am trying to make home telescope, I have a convex lens of focal length 1000mm and eyepiece (plano-convex) with 25mm focal length. What is the ideal distance between objective and eyepiece to see ...
1
vote
2answers
220 views
Can a star turn into a planet?
I have read in a magazine that a star can actually form back to a planet... is it true?!
Does it mean all the planets in our galaxy can be revived back to what they were before?
7
votes
1answer
583 views
Why is detecting brown dwarfs difficult?
Why is detecting brown dwarf stars tedious and not always successful? They emit light in the infrared region, and given that we're surrounded by state-of-the-art technology in space today, why haven't ...
2
votes
1answer
47 views
Where do stellar classes names come from?
Under Morgan-Keenan classification stellar classes are called O, B, A, F, G, K, M, but what is the logic behind these letters? I can't see any pattern and I doubt they have just been chosen randomly. ...
9
votes
1answer
82 views
Is there a relation between mass, radius, and luminosity in deuterium-burning brown dwarfs?
I'm a worldbuilder and my setting has a lot of brown dwarfs.
While I'm trying to keep my setting as science-compliant as possible, I can't seem to find any resources for brown dwarfs like there are ...
3
votes
2answers
163 views
Best way to simulate star sizes to scale in celestial sphere
Using the Hipparcos catalogue, I am trying to create a celestial sphere. As all the stars are a fixed distance from the centre of this sphere, the only way to differentiate the distances and magnitude ...
1
vote
1answer
85 views
Unable to detect stars and constellations in simulation of stars from the Hipparcos catalogue
I am creating a planetarium program using Unity3D and C# to plot out stars from the Hipparcos catalogue. Using the Plx, _RA.icrs and _DE.icrs columns of the dataset, I have managed to work the ...
2
votes
1answer
57 views
What equipment and techniques were used to study Betelgeuse's diameter in 1920?
Comments below What is the maximum distance measurable with parallax? discuss challenges associated with parallax measurements of Betelgeuse and link to Wikipedia’s Betelgeuse; Distance measurements ...
1
vote
0answers
21 views
Bunch of stars moving on sky in triangular and different other shapes [duplicate]
Today I saw different Stars are moving on the sky in shapes of triangle and some randomly. its about 4:20 am in Nasarpur Pakistan and last star I saw at 4:32 am. They are moving in direction (North ...
-2
votes
1answer
98 views
What are the necessary steps required for calculating the size of a star? [closed]
Title pretty much says it all.
Basically, what exact variables are used, and what steps need to be taken, in the calculation of the size of a star? Preferably, some example data for how a the size of ...
2
votes
3answers
63 views
A question about star names… E.G. CW Tauri, DZ Bootis, IQ Lupi, EU Eridani
Take the following examples of star names/identifications:-
Regulus is the common name for a star.
HIP49669 is the Hipparcos ID for the star
HD87901 is the Henry Daper ID for the star
32 Leonis is ...
-8
votes
6answers
330 views
any proof that stars are born, and die?
I've heard from a lot of people that stars are "born" (usually from black holes), then grow bigger, then eventually "die" by some kind of supernova etc., but have any of these events actually been ...
15
votes
2answers
965 views
Are there neutron stars whose magnetic axis and rotating axis are the same, and if so what will happen?
I know that there's probably a higher chance of having a neutron star that has its magnetic axis inclined to the rotational axis rather than having it perfectly aligned.
If they are not aligned, the ...
2
votes
1answer
147 views
How do we measure the brightness of the stars?
How do scientists measure the brightness of so distant stars?
2
votes
1answer
46 views
Orphaned star systems and intergalactic travel (in fictional context)
Context:
I'm looking for some authority on a particular idea that I brought up in regards to a new update brought out for a space travel sim game, Elite Dangerous
The vessels in that game can travel ...
1
vote
0answers
19 views
Lights moving fast and in a straight line coming from the northwest headed southeast tonight at 9:15CST [duplicate]
What is going on tonight?
Bright lights in the same high orbit moving very fast across the night sky from Northwest heading southeast...then 10 minutes later same line but far fewer almost in ...
1
vote
1answer
69 views
Calculating the orientation of the night sky
How would one calculate the rotation/tilt of the earth to simulate the Night Sky in a self-written tool or app. I am trying to built an app for my telescope to show me on my phone what I am looking at....
5
votes
4answers
950 views
Visible Stars in Andromeda Galaxy
So when I look at images taken of Andromeda, I see a lot of individual stars.
Image by André van der Hoeven
It seems to me that the actual individual stars that far away would be too small to ...
1
vote
1answer
63 views
How is the distance of a star from Earth calculated in the HYG star database
The HYG star database can be found here
From the hygdata_v3.csv file, how are the cartesian (x,y,z) coordinates calculated? (Is there a mathematical formula for this?)
And in the dso.csv file, there ...
1
vote
0answers
21 views
Fast moving stars at equal distance in straight line 18.04.2020 evening [duplicate]
Yesterday, I have observed fast moving bright stars at equal distance in straight line (18 March 2020) in Germany around 20:00 in night. I was facing the east direction. What could be the reason for ...
2
votes
0answers
117 views
Identify moving object in the sky at night?
So last night I was looking at the sky at about 8PM EST, and I noticed this really tiny object moving pretty fast from left to right, just between the two stars in the photo. It's very difficult to ...
2
votes
1answer
64 views
Was it a space station?
I just looked at the sky and saw a star, not so bright but moving very fast and in almost a minute it disappeared, as it was so fast.
Timing was in between 9.35-9.45 PM in Nuremberg, Germany.
My ...
0
votes
0answers
76 views
How to extract surface temperature of star from B-V magnitude over all ranges of B-V?
Background:
According to the wikipedia article about the color index, one can approximate the effective surface temperature of a star from its B-V index by the ...
2
votes
1answer
36 views
Is there a relationship between stars' absolute magnitude, spectral class and relative location in a cluster?
I am interested to know whether a pattern has been observed with regard to the characteristics of a star (in particular, its absolute magnitude and spectral class) and its location relative to others ...
0
votes
0answers
23 views
Line of “stars” following one another [duplicate]
Last night (2020.04.08 9.20PM Balerna-TIcino -Switzerland) me and my husband seen a line of "stars,
moving in a straight line at first with some of those moving in different directions.
They kept ...
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
votes
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 ...
