Questions tagged [star]
Questions regarding large spheres of plasma undergoing fusion.
983
questions
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0answers
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Exploded star or object on earth?
I don’t have a telescope 🔭 (which is sad)
Anyways…
Usually in the city, all stars are covered by the light pollution, and that’s my case.
I stare out my window every night, but yesterday night I saw ...
2
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1answer
37 views
Calculate the habitable zone of a star based on NASA Exoplanet Archive
I am completely new to this! I am trying to find if an exoplanet in the Exoplanet Archive is the habitable zone of its host star. My intention is to create a new boolean column in a Pandas Dataframe ...
1
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0answers
45 views
How to determine time when a photo of star trails was taken?
I was asked to define a time (most likely the month) and location of the picture below.
I hope I understood it right that it is the south pole, because we don't see a Polar star in the middle. ...
2
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1answer
42 views
+100
Spectra of different stellar classes?
I'm beyond an amateur, but I've been failing to find this information and it makes me think I'm missing something.
Anyway: I am trying to write a procedurally generated simulation that includes ...
3
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0answers
36 views
Estimate the shape of an object based on flux curve
Is there an aproximation to know the shape of a dust cloud,etc based on the magnitude/flux curves of stars they transit? Example, can I know if the shape is (at least in 2 dimensions) elliptical, ...
4
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2answers
187 views
How to actually obtain the parallax angles that are used to determine distances of stars?
I’m trying to understand how to measure the distance to nearby stars using the parallax method.
My question is: how do you get the value of the p angle?
0
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2answers
65 views
Setting of stars [duplicate]
In the book Thinking Physics by Lewis Caroll I came accross the following exercise:
Using a good digital watch, get the exact time when a bright star goes behind a distant building or tower. A day ...
12
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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 ...
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 ...
0
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1answer
60 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?...
4
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3answers
182 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, ...
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0answers
66 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 ...
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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 ...
0
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1answer
102 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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1answer
92 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 ...
1
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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 ...
3
votes
1answer
470 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 ...
6
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1answer
102 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 ...
4
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4answers
185 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
vote
1answer
100 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
38 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 $...
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 "...
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 ...
1
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1answer
71 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 ...
5
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3answers
717 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
35 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
96 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 ...
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
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1answer
46 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 ...
-1
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1answer
45 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
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?
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 ...
3
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1answer
52 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 \...
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 ...
2
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0answers
38 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
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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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3answers
118 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. ...
0
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1answer
30 views
What does the Reddening line represents in this U-B vs B-V plot?
The plot is from this paper (pg-8).
They have also talked(in the same paper) about how central stars from galactic longitude range $20^\circ-80^\circ$ will have a very unusual Reddening line (pg-9). ...
3
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5answers
212 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 ...
6
votes
2answers
179 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 ...
4
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1answer
126 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$$
The notations are a bit confusing, ...
7
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1answer
93 views
What effect does stellar granulation to have on a chemical analysis of a star's spectrum?
The spectrum from stellar granules will obviously be for hotter gas, while the spectrum from the lanes between them will be for cooler gas.
Does this "average out" so that an average ...
2
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0answers
28 views
Is it possible that absolute magnitude for two stars is equal for some wavelength?
The title explains the questions. I don't find any problem with it. As If the two stars A and B do have equal absolute magnitude for some wavelength $\lambda_0$ then
$$M_A=M_B$$
$$-5(\log d_A-1)+m_A=-...
0
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1answer
45 views
Is something wrong with my luminosity calculation?
A few million years after a white dwarf forms, its surface temperature reaches $100000\text{K}$, while its radius is $0.01R_\odot$. Would this mean that its luminosity is $\Big(\dfrac{100000}{5778}\...
0
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1answer
47 views
How fast would an observer have to travel in order to be able to study an entire star's life in one human lifetime?
Humans live for about 80 years. A star, however, lives from 1 million to trillions of years, depending on its mass. If humans want to have a detailed study of the life of a $1 M_\odot$ star, how fast ...
2
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1answer
47 views
Would studying massive stars that are experiencing time dilation due to proximity to a black hole be useful?
I saw this question (Could a star closely orbit a black hole long enough for the star to have lost 0.5B+ years to time dilation?) and came up with an interesting thought. Massive stars live for less ...
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0answers
69 views
Can someone tell me the contribution of s-, r-, and p-isotope processes to copper?
I have looked for relevant information in the paper Chemical evolution with rotating massive star yields
II. A new assessment of the solar s- and r- process
components before, but unfortunately, it ...
3
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0answers
36 views
What is the theoretical maximum variability a pulsating red giant can have such that a habitable planet can stay habitable for long periods of time?
I was reading about red giants and came across this statement:
Some research suggests that, during the evolution of a 1 M☉ star along the red-giant branch, it could harbor a habitable zone for ...
4
votes
1answer
52 views
Long-lived supernova remnants?
We cannot see the supernova remnant of the star that triggered the formation of the Sun and the Solar System, as the remnant dispersed and became mixed into the interstellar medium. So I am wondering, ...
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0answers
67 views
Physical properties of the stellar corona?
I am after the basic physical properties of the corona of a star, here some questions for which I would like to have an answer, even only for a subset of them:
I know some things about the corona of ...
