Questions regarding large spheres of plasma undergoing fusion.

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9
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3answers
390 views

Statistically, what would the average distance of the closest black hole be?

The closest confirmed black hole is several thousand light years away from earth. Our galaxy has about 100 billion stars. I didn't find any reliable information on the black hole count of ratio versus ...
-1
votes
1answer
132 views

Cluster of fast moving stars

We live in NW Tasmania in a country town and tonight out walking I pointed out a long cluster of stars to my sister as they made an unusual shape but then we realised they were moving really fast - we ...
1
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1answer
57 views

Interfacing FORTRAN programs for model atmospheres with IDL or Python

I'm trying to use model atmospheres such as Kurucz or MARCS for the first time personally and I'm wondering if it is better to wrap it with IDL or Python in terms of writing the code, and getting the ...
-4
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0answers
35 views

Why did the Big Dipper form? [on hold]

There is an asterism comprising 7 stars, known as Saptarishi mandalam, but better known to the Western world as the Big Dipper. It gets its name from the seven rishis. Why did this asterism form, why ...
3
votes
1answer
79 views

Can I get help getting image of Celestial Body at RA 2.220 and Declination +15.59?

My mom had a star named for my dad who died a few years back. I told her that I'd try to find an image of that star and send it to her. My dad's Birthday was 3/31/1931 if that helps. Would love ...
-1
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0answers
31 views

Stars in a straight line [on hold]

I have observed many 2 stars which will be distant but seeing from here it will be in a straight line. Similarly 3 stars which is short distant to each other will be in a straight line. How is it ...
3
votes
1answer
212 views

How many stars would it take to draw a line across the middle of the sky that appeared solid?

I was talking with a friend about how slowly the star field changes (based on the speed that we are moving through the galaxy) and I started to wonder about a star's visible size. They are basically ...
3
votes
1answer
246 views

Do stars start with rocky core?

Is it true that stars start with a rocky core, then collect hydrogen by the gravity of that rocky core, just like planets collecting materials?
6
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2answers
132 views

Does the shape of a supernova remnant depend on the progenitor star's magnetic field?

The magnetic field activity in a star can be very chaotic and my question is are they somehow related?
4
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2answers
84 views

Do constellations change?

Many stars are part of constellations. Due to dark matter the stars have velocities which are nearly the same unregardless their radius of orbit around the centre of the Milky Way. Also, it takes ...
3
votes
1answer
74 views

If a hot Jupiter collides with the parent star, does it enhance or reduce the life of the star?

Suppose a hot Jupiter is collided into parent star due to tidal force, does the life of the star becomes longer due to extra hydrogen, or becomes shorter due to extra mass?
14
votes
6answers
3k views

Is the light we see from stars extremely old?

Our nearest star Proxima Centauri is 4.243 light years away from Earth. Does that mean we are seeing light that is 4.243 years old everyday?
3
votes
1answer
98 views

What may be the period and speed of revolution of the star that is closes to galactic centre?

The Sun moves at the speed of 220km/s around the galactic center in a circular orbit. The sun is located at about 30,000 light years from the galactic center. The Sun orbits around the center of the ...
0
votes
2answers
183 views

Where to get Polaris Right ascension value from

To calculate for example the polaris hour angle I use this formula to calculate polaris hour angle. τ = θ - α τ= hour angle θ= sideral time α= polaris RA (~ 2h32m) But where does the α=2h32m come ...
3
votes
1answer
74 views

Why the light curve goes down when the planet is behind the star?

There is a video explaing the transiting exoplanet light curve — https://www.youtube.com/watch?v=RrusIZaWDW8 It is clear to my why the curve goes down when the planet is between the observer and the ...
3
votes
2answers
289 views

Could the earth become a star if more mass was added?

I've heard that the only difference between a star and a planet is mass, meaning that if planets accredited enough mass they would too become stars. Does this mean that the star started off as a ...
2
votes
2answers
51 views

Is the composition of stars in future made of more and more heavy elements?

In the beginning stars only consisted of the hydrogen element and due to nuclear fusion of those elements in stars and supernova's more heavy elements were created. Because of that, like our Sun, the ...
3
votes
1answer
64 views

Why don't globular clusters flatten with a galactic disc?

Globular clusters lie in the galactic halo, outside of the disc. However, galaxies are more or less a collection of material and objects — why is it, then, that most stars form a plane due to the ...
0
votes
1answer
42 views

How do astronomers distinguish the spectral lines?

As a black body a star emits a continuous spectrum of light and other radiation. I've learned they are capable of knowing of what elements the stars are made of because of the spectral lines. But how ...
4
votes
6answers
2k 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
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0answers
26 views

Negative Spectral Flux Density

I am working on a project and using some satellite images. In some of the images the Spectral Flux Density is negative. What does it indicate?
1
vote
1answer
103 views

Create a signal to noise map from heatmap

Recently, I obtained my heatmap from a sky survey. But now, I'm trying to get a signal to noise map from my heatmap. My heatmap looks like : My colour bar indicates the number of stars per pixel (...
1
vote
1answer
33 views

How to show that the Jeans Criterion for Mass, Radius and Density are equivalent?

The gravitational collapse of a gas cloud can be described by the Jeans Criterion for mass, radius and density of the gas cloud, which is (c stands for cloud): $$M_J = (\frac{5kT}{G \mu m_H})^{3/2} (...
2
votes
2answers
537 views

Definition of stellar core?

This is a basic question, but I may as well ask it. I had always thought that the core of a main-sequence star is defined as the part hot enough for nuclear fusion. Some dictionaries seem to agree ...
0
votes
1answer
116 views

Can a star eject a liquid or a gas that has not been ionized?

Can a star eject a liquid or a gas that has not been ionized? I am implying that these gases could be a source of reusable energy.
1
vote
1answer
436 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 ...
6
votes
1answer
159 views

Why does lithium fuse at lower temperatures than hydrogen?

This is a basic question, but it's been bugging me. In the Wikipedia article for lithium burning, it states that: Stars, which by definition must achieve the high temperature (2.5 × 10^6 K) ...
3
votes
1answer
161 views

Sun from SuperNova

I have read that our sun was created from older star(s) which had exploded in a supernova. If all the matter is travelling away from the central point of explosion, how does it coalesce back into a ...
9
votes
1answer
727 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 ...
0
votes
2answers
86 views

Is it possible to have a star orbiting around a brown dwarf?

I know a single star is almost surely more massive than a single brown dwarf, but consider a case: a very small star is orbiting a very massive brown dwarf which has a very massive moon, such that the ...
6
votes
2answers
144 views

Why is the core of a gas giant supported by electron degeneracy pressure instead of nuclear fusion?

After a Sun-sized protostar forms, its core will become denser over time due to radiation. The core eventually gets dense and hot enough for hydrogen fusion to take place. In the late phases of the ...
1
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1answer
92 views

Mass of Star Collapse

Does a star, when collapsing into a neutron star, or even a black hole, pick up any significant relativistic mass due to its rapid collapse rate?
8
votes
1answer
916 views

How can neutron stars have gaseous atmospheres?

Neutron stars can have small atmospheres. However, they also have extremely strong gravitationally pulls. Shouldn't the all the gas molecules be drawn to the star's surface, and become solids under ...
3
votes
1answer
83 views

In 31.5kyr, Epsilon Eridani and Luyten 726-8 will be < 1ly close; but how distant from the Solar system?

Greetings! Based on Wikipedia and more precisely this paper, it is said that, in about 31,500 years, the stars Epsilon Eridani and Luyten 726-8AB will "meet" at a very close distance (less than 1 ...
2
votes
2answers
134 views

any unique phenomenon when the cores of two planets are aligned with their star's core?

Imagine a line passing through the cores of two planets (in the same planetary system) and their star. Have we ever witnessed this - either with both planets on the same side of the star or on ...
2
votes
3answers
114 views

How do we know that other planetary systems aren't composed of antimatter? [duplicate]

How do we know that other planetary systems aren't composed of antimatter? If they never touch matter, then they don't annihilate. All their observable physics (spectra) are the same as matter, right?
2
votes
2answers
117 views

Solar Pressure and Gravity

I recently read some articles and pages on Solar Sails, and the possibility of using lasers to propel spacecraft, and I had a relatively outlandish idea. Would it be possible for a star to be ...
0
votes
0answers
40 views

Stars repartitions

I'm looking for the stars repartitions in percent, in the Harvard Classification (from O to M) I have search every where but I found nothing. I'm not looking for exact values, but more generic values....
3
votes
1answer
149 views

Do stars tend to fuse all hydrogen even when the mass is small?

Suppose a brown dwarf requires only one more hydrogen atom to become massive enough to start fusion, what will happen if we add a hydrogen atom to it? It fuses until the mass is dropped and then ...
3
votes
2answers
3k views

Is a white dwarf hotter than a Red Giant?

From what I've read, white stars are hotter than red ones. But a white dwarf would have just heavy elements to fuse, so shouldn't it be less bright?
0
votes
1answer
45 views

Metalicity and age of bulge stars vs halo [duplicate]

From what I understand of current models, the bulge of the galaxy formed first, and thus, would contain older population II like stars. Currently, however, the halo has a higher population of stars ...
0
votes
2answers
132 views

Are we made of stars we're seeing? [duplicate]

a fresh astronomy enthusiast here. Recently I've been reading upon how immensely far other stars are from our solar system and how is it possible that we may be seeing stars that are already dead. My ...
1
vote
2answers
66 views

How to interpret extreme ultraviolet/ x-ray data in the literature?

I am interested in a sun-like star 138 light years away that is in the EUVE catalog. A table shows that a photon count of 2.6+/-0.5 photons per kilosecond at 100 angstroms has been detected for this ...
4
votes
2answers
61 views

Why do post main sequence stars enter the red giants branch?

I am an early graduate student in astronomy and have hard time understanding why do post-MS stars move up the RGB. Here is what I understand about post main sequence evolution of stars. As their ...
4
votes
1answer
133 views

Are larger stars rounder?

The Earth is a very smooth sphere, and the Sun even more so, with only minor fluctuations. I am wondering: are larger stars even rounder? Intuitively, that seems self evident, but I am not so sure. ...
6
votes
1answer
87 views

What's the bleeding-edge model for how Population III stars are born and evolve?

I'm trying to do a brief literature review to find out what the best current models for population III stellar evolution are. I was hoping that someone with more expertise in the area could perhaps ...
2
votes
2answers
44 views

Triple stars with retrograde orbits

Where can I find the observed frequency of triple star systems where the outer star is in a retrograde orbit?
3
votes
3answers
160 views

What Makes Stars Hot?

Simple question, but can't seem to find the answer anywhere. It can't be nuclear fusion because nuclear fusion occurs as a result of the heat. And it can't be because of gravity because it's believed ...
3
votes
1answer
139 views

Why is the Sun's brightness and radius increasing, but not its temperature?

On the Sun's article on Wikipedia, there is an image showing how the Sun's brightness, radius and temperature have changed over time: For the past (and next) few billion years, I see the luminosity ...
7
votes
3answers
556 views

What decides the direction in which the accretion disk spins?

Planets lie on the same plane because of the accretion disk formed during the Protostar stage, as I read in this question. I also read about the collision of particles in the gas cloud causing the ...