Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

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2 votes
1 answer
79 views

How do I identify a star in general?

I recently asked quite a few identify-this-object questions, and I think maybe this post can serve as a canonical for how to find a star in general? Note that the pictures that you want to find the ...
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4 votes
1 answer
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What is this yellow star?

In NASAs's August 26 2022 photo of NGC 1156: Does anyone know what the incredibly bright yellow star is on the middle right? Bonus: What's the bright (less bright than the yellow one) blue yellow ...
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10 votes
1 answer
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What is the bright orange star?

After reading this NASA article on Tarantula's Nebula of this image: What is the really bright orange star in the center or upper-left of the young blue stars? The second link further provides ...
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5 votes
1 answer
387 views

What are the blue "stars"?

From NASA September 16 Hubble studies a spectacular spiral: There are 4 really bright blue stars in this photo of galaxy NGC 1961. For those who can't see them very clearly, you can focus on the ...
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1 vote
0 answers
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Satellites or UFOs?

Last night in Greenville MI at around 9:15pm-9:25pm (I don't know the exact time) I saw what appeared to be a satellite appear and disappear and then a few seconds later another possible satellite ...
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4 votes
1 answer
204 views

How do I get temperature and diameter from a light curve?

I recently learned that short-period pulsating stars vary in diameter and temperature when they pulsate. If I have a light curve for such an object, is it possible to calculate the values of its ...
2 votes
0 answers
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M Dwarf radiation and habitability at the terminator of a tidally-locked planet?

I know that M Dwarf stars emit intense solar flares, which is thought to pose a potential problem for the emergence of life on planets that orbit them. But I was wondering if the life that might exist ...
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2 votes
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Pulsations in massive stars

Why are tidally induced pulsations not typical for massive binary stars? For which kind of binaries they are typical? I read it in the last but one paragraph in Discussion of https://iopscience.iop....
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2 votes
0 answers
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What was this "light" that looked like a star moving in line ,disappearing only to reappear where it started?

I was looking in the sky one night about 9:45. There was what looked to be a shooting star but much slower and brighter more like a satellite. It was moving (from standing on earth) it looked like a ...
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0 votes
1 answer
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Classifying stars using GEDR3

Is there a way to take the Gaia Early Data Release 3 dataset and calculate a likely star size (radius and mass) (units not relevant), and emission spectra (hydrogen, helium) or light color? Please ...
8 votes
1 answer
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Do pop III stars undergo supernova or direct collapse?

Population III stars were the first stars to form. They are hypothesised as being very massive, i.e., > 100 M$_{\odot}$. My question regards how do these stars end their lives? An old orthodoxy for ...
2 votes
1 answer
159 views

Is there a centralized database of all stars?

Is there a centralized database for all stars, sourced from Gaia and other missions?
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7 votes
1 answer
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I saw a short-lived brightening and fading of a light in the sky. Was that a star imploding, exploding or going super-nova?

I was looking over the north-eastern skyline from a west coast location and notice something very bright for well over about 10 or 15 seconds, and then it faded completely. I didn't notice it before ...
5 votes
1 answer
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Movement of stars over long periods of time

When the Great Pyramid was built, one long sloping tunnel was aimed at a particular star, which could be seen by a person at the bottom of that tunnel on just one night of the year. Today that star is ...
4 votes
1 answer
156 views

What does the surface of a star look like in visible light?

False colour images of the Sun show a highly complex structure near the surface with matter ejected and suspended in magnetic fields. But are solar prominences and coronal mass ejections visible to ...
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6 votes
1 answer
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Does a more massive main proto-body result in more massive satellites? More satellites?

Suppose that we have a forming protostar and an accompanying protoplanetary disk. Does the mass of the protostar have any direct relation to the masses of resulting planets or amount of resulting ...
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5 votes
2 answers
927 views

Could a quasi-neutron-star exist between the maximum mass of a star and the mass of a quasi-star?

A quasi-star is a hypothetical supermassive star that is so heavy its core collapses into a black hole as it is still forming. The matter accreting into the black hole then generates radiation ...
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7 votes
1 answer
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How and when will Sirius migrating towards the Sun trigger the movement of Kuiper belt objects into the solar system?

Currently the Sirius binary star system is moving towards the Sun at 5.5km/s for roughly the next 60 thousand years or so. At the end of those years it will be 7.8 light years away from the Sun and ...
1 vote
0 answers
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Calculating absolute error in apparent magnitude of a star [duplicate]

I know that the apparent magnitude $m$ of a star is related to its intensity by Pogson's law: $m = −2.5 log_{10} I$. And I also know that the absolute error is defined as follows: Let $\hat{𝑥}$ be an ...
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7 votes
1 answer
489 views

Locate stars in sky from list of (x, y) co-ordinates

Imagine we have a photographic plate that clearly shows a few stars, but we do not know where in the sky these stars are located. We can digitize the location of stars on this plate and now have a set ...
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-11 votes
3 answers
137 views

What exact material are sun spots made from? [closed]

Questions all relate to my theory and original question. Approximate total mass of a sun spot ? Exact chemical composition of a sun spot? Answers please. https://physicstoday.scitation.org/do/10.1063/...
0 votes
1 answer
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python skyfield hipparcos sun mean longitude (L)

I calculate the ra and decl or the stars as below. Can I add the sun's mean longitude L (=M+w) to: ...
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31 votes
2 answers
5k views

Why is one picture of this star blue with red, and the other red with blue?

Someone just retweeted a NASA tweet onto my timeline, and it includes two images, allegedly from the same star that was in the process of dying, taken by the new space telescope, side by side: I don'...
1 vote
0 answers
71 views

Eastern star at night 2022 July 10 [closed]

What is the star in the eastern sky tonight with a moon or planet at the 7 o’clock position?
5 votes
1 answer
70 views

What kinds of stars have viable habitable zones other than G-type stars, and what would life be like orbiting them? [closed]

What would foliage, landscape, and quality of life on dwarf stars and blue stars? Would it be possible for a human to live without high-tech devices and such?
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5 votes
1 answer
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Reason for different surface temperatures of Tau Ceti and Epsilon Indi at similar properties

While looking at a list of nearby stars, I noticed that the spectral classes were not always consistent compared to the masses (and radii) of the main sequence stars. Especially the comparison between ...
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4 votes
1 answer
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Stellar evolution temperature gradient - why the logarithm?

We define the adiabatic temperature gradient as $$\Delta_{ad}= \Big(\frac{\partial \log \mathrm{T}}{\partial \log \mathrm{P}}\Big)_{ad}$$ The goal of this gradient is to show how the temperature ...
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1 vote
1 answer
38 views

What can we learn from the rotation data of a star?

Knowing the speed of a star's surface rotation gives us what data and information. For example, if it is a big star, is it possible to measure distance using the doppler effect? Or can we calculate ...
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3 votes
1 answer
87 views

How can the upper limit for a star's mass be calculated?

I know there is a theoretical mass limit for stars around $300 M_\odot$. But I cannot find a way to calculate that number. I tried to use the "Eddington Limit", but I don't know if I'm on ...
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2 votes
1 answer
169 views

How do I phase fold the light curve for a variable star?

I have some observational data for a star where I've done aperture photometry to get a partial period. I understand that you need to use other techniques to estimate a period for stars whose period is ...
-1 votes
1 answer
107 views

How to calculate metallicity of a star that is made of iron of 20kg and Hydrogen 1000 kg?

I want to know how to calculate star metallicity using only masses of metal and hydrogen of the star. I am attaching my working so far. I am not sure how to exactly calculate the log10(Fe/H) based on ...
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11 votes
1 answer
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What are those stars that cross the galactic center?

I found this GIF by the European Southern Observatory (ESO) in the Wikipedia article on the galactic year, with the following description: Visualisation of the orbit of the Sun (yellow dot and white ...
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5 votes
1 answer
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How many stars can we resolve?

Wikipedia estimates the number of stars in the Milky Way at 100 to 400 billion. One of our most ambitious astrometry projects, Gaia, has been able to resolve and map almost 2 billion stars in the ...
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3 votes
0 answers
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What happens to the non-fusion formed metals in stars?

Let’s consider a population I star of some given metallicity. I know that depending on the type of star, different structures are possible with convection zones and radiative zones trading around ...
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11 votes
2 answers
1k views

Why haven’t we observed supernova events of the hypothetical population III stars?

It’s said that we haven’t observed any population III stars because these stars are too far away, which makes them too dim to observe via small diameter space telescopes. Their light is also extremely ...
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3 votes
0 answers
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How are plage regions related to the density of medium and velocity FeII ions?

During a literature review (abstract), I found that the intensity of FeII (298.5 nm) ions in the last solar minimum was higher than the two previous solar minima 21 & 22. The velocity of FeII ions ...
1 vote
2 answers
108 views

Where can I find a list of galactic Long/Lat for stars?

I can only seem to find right ascension and declination, which if I understand is position when looking upwards, where as galactic long/lat should be position if you imagine a sphere of the plane of ...
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1 vote
0 answers
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Why do we estimate the Minimum mass when we are dealing with exoplanets?

While solving astronomy problems dealing with exoplanets, I always see that the question asks for minimum mass instead of the mass. Why is that so and why is the calculated mass minimum mass? example ...
2 votes
0 answers
40 views

Where can I find galaxy rotational data?

I want to do a small project of generating rotational curves for different galaxies, and need data for some prominent stars in other galaxies (data needed: distance from center, rotational velocity) ...
8 votes
1 answer
1k views

Rotation direction of Pulsars

Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. It has a very strong magnetic fields which funnel ...
5 votes
1 answer
454 views

When was/will Polaris's declination be maximised?

When was/will Polaris's declination be maximised? In what year was/will Polaris be closest to the north celestial pole.
15 votes
1 answer
741 views

Has a magnetic field flip of a distant star ever been measured?

The magnetic field of the Sun flips during each solar cycle, with the flip occurring when sunspot cycle is near its maximum. Levels of solar radiation and ejection of solar material, the number and ...
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0 votes
1 answer
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Convert from spectral type to RGB color?

I'm writing a night sky simulator and I want to render stars using the correct color. Is there a formula that converts a two-character code (as seen in the Yale Star Catalog) to a RGB value?
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4 votes
2 answers
107 views

What stars am I seeing in the daytime?

I currently live in the United Kingdom, in an area where the overall elevation is high so while the hills are rolling rather than peaky, they are all well above sea-level. A few weeks ago I was on a ...
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5 votes
1 answer
174 views

How far away from us was Earendel star when it emitted the light that is just now reaching us?

From what I've read, the look back time is about 12.9 billion light years, and the current distance to the Earendel star is approximately 28 billion light years... How close to us was it when it ...
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49 votes
1 answer
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Is there a better explanation of this picture showing the very distant star "Earendel"?

"Close-up of the tiny region where Earendel happened to fall right on top of the narrow line where the magnification increases by (tens of) thousands of times. A cluster of many stars is seen ...
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2 votes
1 answer
96 views

Could Hawking radiation turn a black hole back into a star?

Would a black hole after eons of losing mass due to Hawking radiation, eventually turn into a burning star again? As it’s pressure will no longer be overwhelmed by the gravity it once had and through ...
10 votes
1 answer
4k views

What is this, red, blue, white twinkling, star? [duplicate]

I am from Germany and at 11 PM I was outside and I saw a star, rapidly twinkling in blue, red and white. At first, I thought it was a plane, but it didn't move. I took a picture of it, but you can ...
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1 vote
1 answer
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Using Saha's equation knowing the overall pressure

Knowing the pressure, $P_g$, how can I calculate $\frac{N_{I+1}}{N_I}$ using Saha's equation? If I assume that $P_g=(n_e+n_{H^+}+n_H)K_B T$ and that $n_e=n_{H^+}$, I can find the electronic pressure, $...
3 votes
2 answers
387 views

Deriving the apparent angular speed of a star

The angular speed of stars in the sky is constant but the apparent angular speed is not, due to the star moving faster on the celestial equator and slower near the celestial pole. The apparent angular ...

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