Questions regarding large spheres of gas undergoing fusion.

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1answer
45 views

When stars explode why can we still see them?

This might be a silly question but if light travels at the speed of light and time is frozen in that speed then why the stars we see could be dead already and not just instantly disappearing from the ...
3
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1answer
316 views

Where do new stars get their hydrogen from? [duplicate]

When stars run out of hydrogen, they explode (though they also use heavier elements for some time) and form nebulae. In the nebulae, new stars are born which use hydrogen as their fuel. So, my ...
6
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1answer
375 views

How do star densities work?

If we take a look at stars more massive than the Sun, their densities vary a lot. UY Scuti is an extremely low-density star that's only 8.5x more massive than the Sun, but is 1000-2000x its size. ...
4
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1answer
52 views

Why do pre-main sequence stars show lithium in absorption?

This paper and this paper state without discussion that the presence of lithium absorption in the stars they observe as strong evidence of these stars being pre-main sequence stars. Because they state ...
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1answer
21 views

How to see other celestial things using stars for direction?

I have a simple question. I can see orion constellation clearly in the night sky. I read it somewhere on this website that gemini is on the left-hand side of orion constellation. I was able to spot ...
-2
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1answer
42 views

Can a drastic change in a stars cycle cause harm or affect a nearby star system?

If Alpha Centauri A our neighboring star happens to shift into a Red Giant or a Planetary Nebula, Will our star system be affected? And if so is there a ripple effect throughout the galaxy causing a ...
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0answers
30 views

Angular Separation

Two stars A and B are located on the celestial equator. The RA of star A is 02h 0m 00s and that of star B is RA 07h 00m 00s. What is the angualar seperation between star A and B?
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2answers
103 views

Why are stars more metallic closer as you move closer to the galactic bulge?

As I see it, most of the stars in the galactic bulge are Population I stars. However, as one moves farther from the galactic bulge, star metallicity decreases. In fact, halo stars are almost entirely ...
2
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1answer
129 views

Are stars really “burning balls of gas”?

Even the NASA website refers to stars as "big ball of gas". It's a common statement that's popularized by movies and popular culture. However, stars are technically not in a gaseous state - they're in ...
3
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1answer
186 views

Are there good animations of the movement of proximate stars over long time periods?

After reading about Barnard's Star and how it's approaching us 140 km/sec, I'm curious if there are any visualizations of how the nearest stars to Sol will be moving over the next 100k years or so. ...
4
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3answers
269 views

Could the KIC 8462852 (Alien megastructure star) be explained by orbiting gas clouds?

I was wondering about the light dimming of the 'alien megastructure' star. From what I understand, for it to be a planetary body, it would have to be some 20 times the size of Jupiter. Is it possible ...
0
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1answer
39 views

Epsilon Eridani and Sadira

I have seen a number of places on the Internet where Epsilon Eridani is referred to as Sadira. (e.g. https://en.wikipedia.org/wiki/List_of_stars_in_Eridanus ) However, it would seem that its an ...
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1answer
62 views

Number of stars & planets in Milky Way Galaxy?

Is there any specific numbers on stars & planets count on Milky Way Galaxy ?
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1answer
48 views

how to get image coordinates of source points in saoimage ds9?

I loaded my fits image to saoimage ds9. Then, Analysis->Catalogs automatically brought up source locations. how can i get xy image coordinates of this source locations?
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0answers
61 views

Formulas for gravitatitional equilibrium

I am trying to calculate at which point gravitational equilibrium sets in for various bodys (planets stars neutron stars etc.) assuming they are perfect spheres. However the radius i get is not equal ...
1
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1answer
49 views

Obtaining stars vector position in relation to the center of the galaxy at a given date

How can someone obtain such vector, for stars in the Milky Way? Input should be star data (from a catalog, eg: Hipparcos) and Julian Date. Output should be a Vector Position (in pc) in relation to ...
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2answers
34 views

Do massive OB stars accrete mass the same way as the black holes they turn into do?

It is often said, in spite of sci fi often having illustrated the opposite, that stellar mass black holes do not gravitationally attract material in their environment into themselves anymore than a ...
3
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0answers
38 views

What is the frequency distribution for luminosity classes in the Milky Way Galaxy?

I'm working on a game concept that does some mild simulation of realistic stellar classes and luminosities. In particular, I'd like to roughly model the general frequencies of the classes and ...
9
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1answer
451 views

Is the Sun really a medium size star?

It is often said that the Sun is a medium size, or even dim star, but is that true? According to this list of stars within 21 light years, only six stars are brighter than the Sun out of the closest ...
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0answers
32 views

Calculating AZ and ALT from RA and DEC: values are slightly different from Stellarium

I'm developing my own planetarium software and I using Stellarium to check if the values a get from my software are correct or not. All values are roughly equal, being different only in the seconds. ...
3
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1answer
91 views

How can we hear the sound of the Sun?

Recently NASA has revealed that they have recorded the sound of Sun. They say that it produces a sound like "Om". I can't understand how they can hear it. To the best of my knowledge, sound can't ...
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0answers
12 views

Dust mass-loss rate from a massive star given a set of parameters?

I've been looking for examples at how mass-loss rates are determined. I'm studying a circumstellar dust shell ejected from a Wolf-Rayet star. I have some parameters like, expansion velocity of the ...
0
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1answer
138 views

How to calculate the temperature of a star

I need a way to calculate the effective temperature (surface temperature) of a star for a stellar model. I need something in the form Te=.... I have: Radius in m mass in kg the composition of ...
0
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1answer
24 views

Conversion from Equatorial Coordinate to Horizon Coordinates

I'm developing my own Planetarium software using C++ following the book Practical Astronomy with your Calculator or Spreadsheet 4th Edition. I don't know if I my formulas are correct or not, but when ...
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0answers
31 views

Which is the most accurate stars catalogue for J2000 epoch?

I'm developing a planetarium software. I have no idea about how to obtain stars right ascension and declination. Searching on Internet I have found that Wikipedia has AR and DEC for a lot of stars. ...
5
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1answer
167 views

Can a star have a ring system?

I often hear about planetary ring systems, and even some moons might have them, but how about stars? Can a star also have rings?
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1answer
45 views

Do the magnetic fields of stars and/or other planets reverse?

I've heard of the magnetic field of the earth reversing poles over the course of thousands of years but do stars and other planets (specifically gas giants) also experience this? If so how does it ...
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3answers
117 views

Why is it always planets orbiting stars?

In our solar system, there are 8 planets orbiting a star, the Sun. And I understand that there are about 500 confirmed solar systems out there. But why is it always planets orbiting stars? Why can't ...
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3answers
230 views

How Would a Neutron Star Actually Appear?

Having seen many pictures produced by artists of neutron stars and planets that orbit some of them, I was wondering how a pulsar would appear to a human being, in visible light (assuming the intense ...
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2answers
87 views

Can any stars ever form supermassive black holes?

I heard that most supermassive blackholes are not formed by stars – in fact, we aren't even sure how they're formed. But could a star, with enough mass and low enough metallicity, form a supermassive ...
64
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2answers
7k views

How loud would the Sun be?

Sound can't travel through outer space. But if it could, how loud would the Sun be? Would the sound be dangerous to life on Earth, or would we barely hear it from this distance?
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2answers
93 views

How many stars are in the constellation Canis Minor?

I've read Wikipedia and found a list of stars in Canis Minor, and counted the number of stars in the list. I came up with 56 stars, a surprising number. I did some more research and found that Canis ...
3
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1answer
72 views

How to cool down a moon?

I'm doing an Astronomy project and need to terraform a moon. It is about the size of Mars and orbits a gas giant which is at a distance of 1.28 AU of its star. I though about putting a sunshade at the ...
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6answers
3k views

Are we still going to have rainbows if Sun is replaced by another star?

Rainbow is a property of light splitting due to the water molecule present in the clouds and is related to the light emitted by our Sun. Our sun is a yellow star. Now if we replace sun by a blue giant ...
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2answers
61 views

Betelgeuse and sun classification

In this video, between 4 and 6 minutes, the lecturer describes M type stars as being less massive, smaller, and redder than G type stars. He then gives Betelgeuse as an example of an M type star and ...
2
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1answer
74 views

When is it a good aproximation to consider a star to be an ideal gas?

I am currently taking a first course on stellar astrophysics, and I noticed that in some cases we use the ideal gas equation of state for stars, so we also use $\gamma =5/3$. Of course it can only be ...
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1answer
47 views

What is the illuminance of Tau Ceti?

As part of my physics project, I investigated the relationship between a light bulb's illuminance and the distance from the measuring device to it. Illuminance was measured in flux, and distance in ...
3
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1answer
299 views

Why do certain massive stars leave no remnants?

Mass and metallicity are the two main determinants for a star's fate. This is simple enough. What's more complicated is how exactly these determine the star's fate. For example, you can see in this ...
2
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1answer
79 views

Can a star orbit around multiple planets or a planet with massive moons?

Note: I'm not talking about a star orbiting around a single or lonely planet :) I know a star orbiting a planet is almost impossible because if a planet is more massive than a star, that "planet" ...
4
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1answer
71 views

How many stars are in the Sculptor Dwarf Galaxy?

The Sculptor Dwarf Galaxy is a small satellite Galaxy of the Milky Way. There are many such satellites galaxies and I'm trying to compile basic data on them. However, I can't find an estimate for the ...
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0answers
40 views

Stellarium script star of bethlehem

Does anyone out there have a script to replicate the star of Bethlehem. In this case meaning a conjunction of Venus and Jupiter near Regulus.
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2answers
73 views

Can quantum entanglement cause nucleosynthesis to happen in stars?

Even if there isn't enough heat and energy in the star to cause nucleosynthesis, could atoms quantum entangle to create a new atomic nuclei? Or would it be quantum tunneling - if this is possible?
3
votes
1answer
77 views

What is the scale of things you can see with gravitational lensing?

I'm trying to understand the examples of gravity lensing (using the general relativity property of large masses to bend light like a lens). Most of the examples I see are of some galaxy (presumably ...
1
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1answer
51 views

A black hole that doesn't take in matter?

According to List of Common Misconceptions by Wikipedia, under the heading of astronomy, this line can be found: A black hole can act like a "cosmic vacuum cleaner" and pull a substantial ...
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1answer
50 views

If any object could become a black hole, could any object become a neutron star?

A black hole doesn't necessarily need to form from a star; theoretically, it could form from any extremely dense object. In fact, many astronomers differentiate certain black holes, like supermassive ...
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1answer
52 views

If there are neutron stars, would most stars be considered “proton stars”?

For example, the Sun is a giant sphere of positively charged plasma. About 72% of the elements in it are protium. This means that these protium atoms would have had to lose their electrons, right? If ...
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1answer
44 views

How can I determine line luminosities from equivalent width measurements?

I have a set of equivalent width measurements for different emission lines. How can I use them in order to determine the corresponding line luminosities?
5
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1answer
106 views

How small a star can provide Sun-level illumination to its planets?

...or how small can a solar system be, to sustain an Earth-like planet? Sun is not really small, and 1AU is pretty far when you look at orbital radii of exoplanets and size of their stars. How small ...
2
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1answer
47 views

Divide a star catalogue to optimize star search

I'm continue working on my Planetarium software and I have a doubt. At this moment my star catalogue is very small, but I'm planning to use a bigger one. To optimize the search inside this catalogue ...
3
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1answer
57 views

Is the size and heat of a star important in the development of a solar system?

How do the size and heat of stars affect development of solar systems and what kinds of planets can develop? Is it possible to orbit supermassive stars? Furthermore, would star's unleashing violent ...