Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

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11
votes
3answers
1k views

Can a small black hole orbit a large star?

I recently read about the discovery of a tiny black hole (with only three times the mass of the sun) nicknamed ‘The unicorn’ about 1500 light years from earth. This got me thinking, can this black ...
4
votes
3answers
119 views

Are stars rotating?

This question may sound silly but I'm really not pretty sure whether stars are rotating or stationary. If they are not rotating what makes them to be stable?
4
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1answer
90 views

Reference for equation of state?

I am a post graduate studying mathematics and currently working on the mathematical theory of stars though not an expert. When I am making some assumption about the equation of state (for a star or ...
3
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2answers
291 views

What star is the closest to Betelgeuse?

Based on this answer, I should be able to figure out this question, if I know the distance between Betelgeuse and its nearest neighbor. So what is Betelgeuse's nearest neighbor? I do mean the ...
18
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3answers
4k views

How are constellations intact if the stars are rotating around galactic nuclei?

From what I understood, the Milky Way (or stars in the Milky Way) doesn't rotate like a collection of points in a disc due to the presence of some invisible matter. In theory, the angular velocities ...
29
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2answers
24k views

How many stars and galaxies can be seen by the naked eye?

How many of the luminous dots that we see naked are galaxies and not stars from our galaxy? I imagine that the majority of the luminous points that we see naked eye during the night, are actually ...
6
votes
2answers
178 views

Are any supergiants translucent?

Are any supergiants translucent? Some have volumes thousands of times more than the Sun's while having maybe twenty times the mass of the Sun which makes them sound rather diffuse. If there was a very ...
2
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2answers
159 views

Why doesn't smashing larger and larger bodies incrementally into a rocky planet create a star?

Let's start with a stationary Earth. If we smash a few Mercury-sized objects into the Earth, the Earth begins to accrete mass. Repeat this step with larger and larger objects, until we start impacting ...
0
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1answer
58 views

What colors do other stars have when seen from space close to them?

The Sun looks yellow from Earth because we see it through the atmosphere; in space the Sun looks rather white. Do A-, B- and O-type stars look blue from both their planet's atmospheres and outer space?...
2
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3answers
136 views

How do astronomers know that distant galaxies aren't actually nearby star clusters?

When reading about the recent release of data from the Dark Energy Survey, and the 'pictures' of well over 200 million distant galaxies, I got to wondering: How can they know that a small, faint, ...
4
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2answers
2k views

How can the (in my eyes quite ridiculous) conjecture of Sheldrake be disproven? [closed]

In this question on the physics site, it is asked if astronomical objects can be conscious. Now, in a sense, every object has to be "conscious" somehow, as every object is composed of the ...
3
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3answers
112 views

How can you determine the date using nothing but a star chart from the day and the time?

I'm doing a science olympiad event called Reach for the Stars, and one question that I've encountered provides a star chart and time of day, and you must figure out what month of the year it is from. ...
2
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2answers
651 views

about H$_\alpha$ and H$_\beta$ lines in astronomical objects' spectra

Generally there may be some line ratio between the two lines. If H$\alpha$ is strong, it is quite possible we can see H$_\beta$ too. Is it possible we can see H$_\beta$, but can not see H$_\alpha$? ...
1
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0answers
34 views

Bright light in sky that slowly faded away [closed]

North Carolina June 5th 2021 at about 1:45 a.m. my boyfriend walked to me to my car just to see a bright like just above the tree line. Didn’t think anything of it. Finished our goodnight talk and ...
3
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1answer
84 views

Can Stellar Spaghetti ever escape?

Spaghettification is the deformation of a body into long, thin strips due to tidal forces as the body passes through a powerful gravitational field. Image from wikipedia: Stellar spaghetti has been ...
0
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1answer
83 views

If Proxima Centauri goes supernova will it negatively affect the Earth? [duplicate]

Proxima Centauri is the closest star to the Earth (besides our Sun). If it went supernova, would such an event negatively affect the Earth? Can Proxima Centauri negatively affect the Earth in some ...
3
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0answers
44 views

How to distinguish primary hosts (stars) and orbiting satellites (planets) and tertiary bodies (moons) by their mass and trajectory?

Suppose one has run a gravitational simulation of N bodies (has the mass, vector positions, vector velocities, etc for each body), but knows nothing a priori about ...
4
votes
2answers
485 views

Why is Proxima Centauri called Proxima Centauri?

It seems very logical, to call the star, closest to earth, "Proxima" ("Proximus" is Latin for "close" and the word for star, "stella", is feminin, hence "Proxima"), but there's one thing I don't ...
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0answers
20 views

Why red giants have cooler surface than MS stars?

I know that with increasing age and depletion of hydrogen in the core the radiation inside a main sequence (MS) star increases pushing the envelope/surface of the star outwards. What I don't ...
1
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1answer
36 views

Is HR 5171 a Spectroscopic Binary or a Symbiotic?

Is HR 5171, the largest yellow star in the galaxy a symbiotic star where one feeds off the other? Or is it a spectroscopic binary where its only possible to determine that there are two stars by ...
1
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2answers
60 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 ...
4
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2answers
441 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 ...
1
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2answers
156 views

Why does the Gaia color-magnitude diagram have this shape?

I was looking at the visualization tools of Gaia, and tried plotting a color-magnitude diagram. On the right hand side of the image, photGMeanMag (mag) (the amount ...
5
votes
1answer
310 views

Creating an HR diagram from tabulated stellar data

I teach statistics and study Astronomy. I'd like to create an activity for my statistics students using star data. They could enter the data into Excel and create an HR diagram. We are currently ...
6
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1answer
99 views

Missing supernovae in the Milky Way

Stars with more than 8-16 solar masses usually go supernova. These are OB stars, of which 0.2% currently exist in our galaxy. The average lifespan of said star ranges from 10 to 40 million years. So ...
3
votes
1answer
449 views

Does Oxygen-burning process produce Neon?

In the book "Horizons_ exploring the universe-Cengage learning (2018)", p200, it states that: Helium fusion produces carbon, and some of the carbon nuclei absorb helium nuclei to form ...
2
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1answer
65 views

Catalogs for type K stars and their planetary systems?

I am doing data collection on all type K stars, and their planetary system so I may develop an algorithm for a planetary formation simulation with the Unity game engine. Where could such a catalog of ...
17
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2answers
2k views

Hydrogen burning vs Hydrogen fusing

Does the term "Hydrogen burning" mean the same as "Hydrogen fusing" in astronomy? If not, then what is the product of "Hydrogen burning"? Assume the product of "...
4
votes
4answers
179 views

Gravity inside a star?

Recently, I answered this question and need some clarification regarding the gravity when within the radius of a star. I thought that, when something is inside a star (ignoring drag), it will ...
1
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1answer
96 views

If a black hole has a mass similar to a star, why does it have a different gravitational pull?

Say there is a black hole with 1 solar mass, having the sun's mass, it would have the same gravity as the sun, right? But it still has an event horizon, so why does it have such a strong gravitational ...
1
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1answer
35 views

Have all Wolf-Rayet stars evolved off the main-sequence?

From what I've read from various sources, Wolf-Rayet stars are massive, evolved stars that typically are the hottest, most luminous stars known. They experience high mass loss, taking their mass from $...
5
votes
3answers
715 views

Were there any images of Sanduleak -69 202 (progenitor of SN1987A) before it exploded?

We all know about SN1987A, the closest observed supernova since Kepler's time. Its progenitor was Sanduleak -69 202, a magnitude 12 blue supergiant, catalogued in 1970. Were there any images of this ...
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0answers
33 views

Why is VX Sagittarii classified as spectral type M4-M10?

The largest and most luminous asymptotic-giant branch (AGB) star is VX Sagittarii. Wikipedia states that its spectral type is M4eIa-M10eIa (citing https://arxiv.org/pdf/astro-ph/0608438.pdf which in ...
1
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1answer
70 views

Fusing and buring of Helium core/shell

In the book "Horizons_ exploring the universe-Cengage learning (2018)", p196, it states that The nuclear reactions in a main-sequence star’s core fuse hydrogen to produce helium. Because ...
1
vote
1answer
91 views

Why is it impossible for a Quasi Star to exist these days? [duplicate]

I've heard about quasi stars a while ago, but I've just recently decided to go more in-depth about the characteristics and facts about them. I learned that they gain their energy through radiation ...
2
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1answer
81 views

How does the stellar evolution for low and intermediate mass stars differ?

I'm trying to understand stellar evolutionary tracks for different masses. So far I have the general understanding from a cloud of gas and dust to a white dwarf, neutron star or black hole. What I don'...
-1
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1answer
43 views

Graphing the evolution of stars on an HR diagram with timesteps

I have found countless images regarding the evolution of stars, plotted on an HR Diagram, like so (found on Wikipedia): Although this displays the time in each stage, it does not include any points ...
0
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0answers
14 views

Photosphere Thickness and Pressure vs stellar type

Where can I find information on how the thickness and pressure of a stellar photosphere is expected to vary with star type (temperature). I, as an amateur, have attempted a "simple" analysis ...
1
vote
1answer
45 views

Clear boundary between core and shell of a gas star

Does a gas star have a clear boundary between its core and shell? If it does, then what is keeping a helium core distinct from its hydrogen shell, for a main-sequence star that transforming to a giant ...
3
votes
1answer
50 views

How is the difference of bolometric magnitudes not dependent on the stars' radii?

The difference of 2 bolometric magnitudes is given by: $$M_{bol, ★} - M_{bol, ☉} = -2.5 \cdot \log \left( \frac{L_★}{L_☉} \right)$$ But Pogson's equation is: $$M_{bol, ★} - M_{bol, ☉} = -2.5 \cdot \...
0
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0answers
30 views

Where to find all spectroscopic data about 28 CMa?

I am searching all available spectroscopic data (and particularly wavelength interval) of 28 CMa in the constellation Canis Majoris to measure radial velocities. Which database should I use?
3
votes
2answers
131 views

Which star has the highest mass loss rate?

We have known lists of stars with high luminosity, temperature, mass, size, and much more. However, I have not seen a list that compares each star's mass loss rates. So, which star (or stars) have the ...
1
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0answers
36 views

Dotted line of moving objects observed on May 5th and May 12th [duplicate]

I saw a dotted line shooting star-like object May 5th and May 12th. It was longer than any meteor/shooting star tail or trail I've ever seen before. I mean longer in every way, the distance it ...
1
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0answers
32 views

singular star moving in the sky, can’t be satellite nor shooting star [duplicate]

so i was just setting up my camera for some long exposure photography and just as i was about to take the picture, a star seemed to be moving in the sky on its own. there was no contrail like a ...
4
votes
1answer
125 views

Given that a color index ($B-V$) of star A is lower than that of Star B, What can we say about the stars?

The color index $B-V$ of the star is defined as $$B-V\equiv M_B-M_V$$ Let us suppose it's given $$(B-V)^{(A)}<(B-V)^{(B)}\Rightarrow M_B^A-M_V^A>M^B_B-M^B_V$$ The notations are a bit confusing, ...
5
votes
2answers
326 views

How to determine the age of a star using asteroseismology?

I keep reading that a standard way to determine the age of a star is asteroseismology, and I tried to learn more about it. I am wondering if somebody could help me to describe the method in simple ...
7
votes
1answer
93 views

What effect does stellar granulation to have on a chemical analysis of a star's spectrum?

The spectrum from stellar granules will obviously be for hotter gas, while the spectrum from the lanes between them will be for cooler gas. Does this "average out" so that an average ...
2
votes
0answers
37 views

How to determine the temperature of a star according to the strength of the line in the spectra?

Based on the comments, I have changed some things. Below is a graph showing the relative strength of $H_\gamma$ and Fe I lines of two stars. Which star is hotter? This is a question from the book:An ...
12
votes
2answers
2k views

What is that donut-shaped object I see in my telescope? [duplicate]

I was looking through my telescope for the first time and came across this weird star. I think its a celestial donut but im not sure.
3
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5answers
206 views

If our galaxy is mostly empty space then why does it look so solid?

This question has probably been asked quite a few times, but I'm having trouble finding anything due to the fact that this question is very specific in nature. So I'm asking again. We know that outer ...

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