Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

Filter by
Sorted by
Tagged with
8
votes
3answers
4k views

Why are stars so far apart?

So, this is mere musing, but it seems that stars are quite extremely far apart. I tried to determine the mean distance between nearest neighbors for stars (in just our galaxy) but I'm not sure what it ...
0
votes
1answer
52 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
24 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 ...
23
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
0answers
270 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 ...
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
50 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
83 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
49 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
32 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
55 views

How do I calculate the surface temperature of a star from luminosity?

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 ...
6
votes
3answers
159 views

What is the spectral reflectance of starlight in a close binary?

Ignore the Blender Monkey! (from here) In a close-orbiting binary pair, a small but significant fraction of the light from each star falls upon the other, and the result has to be carefully modeled ...
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
29 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 ...
7
votes
2answers
2k views

Why does iron consume more energy in the fusion process than it produces?

I understand that once a star starts fusing iron, it's doomed to collapse because iron fusion requires more energy than it releases in the process, allowing the opposing gravity of the star to cause ...
1
vote
1answer
37 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
217 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
582 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 ...
1
vote
1answer
67 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 ...
5
votes
3answers
5k views

Fate of Jupiter when our sun dies

Five billion years from now, the sun will have grown into a red giant star, more than a hundred times larger than its current size. While this metamorphosis into the giant star will change the solar ...
2
votes
1answer
45 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
79 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
141 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
50 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 ...
3
votes
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 ...
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
96 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
321 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 ...
11
votes
6answers
6k views

Where can I find a catalog of all stars in the Milky Way?

Is there a catalog of all known stars or brightest stars in our galaxy? Preferably with some sort of galactic coordinates instead of just night sky coordinates (right ascension, etc.) I'm trying to ...
15
votes
2answers
961 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
129 views

How do we measure the brightness of the stars?

How do scientists measure the brightness of so distant stars?
2
votes
2answers
3k views

Calculating star radius from temperature and absolute magnitude - what am I missing?

In an attempt to visualise nearby stars, I've tried to get the star radius (measured in solar radii) using the equation provided on the following site: http://cas.sdss.org/dr4/en/proj/advanced/hr/...
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
1answer
61 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
916 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
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 ...
2
votes
5answers
1k views

Stars in constellation patterns by catalogue number?

I need a resource that can tell me the stars that make up a constellation (pattern), preferably by Henry Draper or some catalogue number? All i can find is lists of every star in a constellation (area)...
1
vote
1answer
62 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 ...
4
votes
1answer
206 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 ...
2
votes
1answer
63 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 ...
2
votes
0answers
91 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 ...
8
votes
5answers
1k views

Are the stars in constellation located in a plane or they are in different distances

Are the stars in constellation located in a plane or they are in different distances from each other and when we observe them from the Earth we think they are all in a plane?
0
votes
0answers
40 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 ...
11
votes
3answers
508 views

Perceiving movement of stars

Are there any stars visible to the naked eye whose position, over a normal human lifetime, can be seen to have changed (relative to other stars in the vicinity)?
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 ...
2
votes
1answer
59 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 ...
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 ...

1
2 3 4 5
16