Questions tagged [star]
Questions regarding large spheres of plasma undergoing fusion.
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Is the sun's classification wrong
Curious Question here.
How do we know the Sun is a G-Type Star?
If G-type Stars range from 5,000 Kelvin to 6,000 Kelvin (Yellow/white)
And our sun (Classed as G2V) apparently lies around the 5,780 ...
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In layman's terms, why does the cold C-N-O process end in Carbon?
I read up a little bit on fusion in stars, layman's articles only and the P-P chain makes hydrogen or Alpha particles. The Triple-Alpha process makes Carbon and the C-N-O process (lets limit this to ...
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Velocity of the object in Binary system
how to i can calculate the velocity of the object? If i know the distance of the object from the center of mass, and i know distance between the two (identical) ellipse center... (the two object has ...
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Does anyone have the skymap match to the temples on earth's surface? For the date of about 10,500 years ago?
I am writing a paragraph about it, and I can't find it.
I saw it about 10 years ago.
All temples on earth's surface match a specific date around 10,500 years ago.
I need that skymap please.
Cheers;
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Are main-sequence G9 stars habitable?
Our sun is a G-type main-sequence star. Specifically, it is classed as a G2 star.
Meanwhile, 18.8 lightyears away, is a star called sigma draconis, or Alsafi to use its more common name. Modern ...
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Was Galileo expecting to see so many stars?
Beginner amateur here. I see mentioned many times that Galileo was surprised to see the moons of Jupiter and all that their existence proved, i.e. the Earth not necessarily being the center of ...
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Finding ones way around the sky
Thinking about this recent question Identify T-shaped constellation the first thing I have to say is that I applaud the poster for actually looking up and noticing the stars: something that becomes ...
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How to calculate the distance from earth and Vega in 1000 years?
Hello I read that Vega is getting closer to earth.
I would like to learn how to calculate its displacement and calculate the galactic coordinates that it will have next year or in 1000 years.
Knowing ...
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How can I Mathematically Calculate the Luminosity of a Post-Main-Sequence Star from Mass and Age?
So, I saw this question (which is quite old) and that's all well and good, but what if I need to (very) roughly calculate the luminosity of a star from the end of the main sequence? Let's assume that ...
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Search good image for observable sky as seen from earth
I am searching for a good image that explains the field of view as seen from a certain latitude. Example: an observer standing on earth has limited view due to the horizon. Furthermore, he sees all ...
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Is there more dark matter than we previously thought?
With the recent Nature publication showing that M dwarfs did not form in prior epochs as frequently as we had thought, what implications does this have on galaxy mass estimates and, by extension, the ...
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Modeling binary star using MESA
I'm trying to model a binary star using the MESA (Modules for Experiments in Stellar Astrophysics docs) code with an orbital period of 10 days with the scenario where mass transfers starts after the ...
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Is Barnard's star an M4 red dwarf or an M0? Why is it called an M4.0V?
I have tried to figure this out, but cannot find an answer anywhere...
Are, perhaps, astronomers unsure of its exact spectral class? (I have heard that red dwarfs are usually variable... to an extent....
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What causes the Balmer Jump?
To quote Wikipedia:
Balmer Jump is caused by electrons being completely ionized directly from the second energy level of a hydrogen atom (bound-free absorption), which creates a continuum absorption ...
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Equation describing Energy Transport due to Radiation in the interiors of stars
I am considering a very elementary stellar structure and I'm required to derive an equation to describe the energy transport due to radiation. The answer I am supposed to obtain is:
$$\frac{dT}{dr}= -\...
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calculate the absolute and apparent magnitude for a binary star system
I'm used to use this formula to find the apparent magnitude of a star
$$m_1 - m_2 = -2.5 log(\frac{f_1}{f_2})$$
If both star are at the same distance from us and their luminosity is the same, does it ...
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Is it possible for a star cluster to be composed of main sequence stars?
From what I hear about globular clusters, they are primarily composed of very hot giant stars, which are not the most conducive for life as we know it.
Main sequence stars like our own, due to their ...
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Which stars are elliptical galaxies constituted by?
I know that elliptical galaxies are old galaxies, with almost no star formation and an old stellar population. This can be seen by their dominantly red spectra in the optical. I am trying to get a ...
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How do amateur astronomers do stellar spectroscopy?
This question consists of 2 parts:
How can amateur astronomers measure the spectrum of stars?
In addition to diffraction gratings, what equipment do they use (like telescopes, and the focal length ...
user47732
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What is this drawing about in "kitab al bulhan"?
Kitab al bulhan or "book of surprises" is medieval Persian manuscript written in Arabic.
According to Wikipedia:
The contents include subjects on astronomy, astrology and geomancy, ...
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In the context of stellar nucleosyntheis, is Xenon-130 a primary or secondary isotope?
With the definitions: 'a primary isotope is any isotope which can be synthesised in a star which starts its life containing only hydrogen and helium', and a secondary isotope is any isotope which ...
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In the context of stellar nucleosyntheis, is Xenon-130 a primary or secondary isotope? [duplicate]
With the definitions: 'a primary isotope is any isotope which can be synthesised in a star which starts its life containing only hydrogen and helium', and a secondary isotope is any isotope which ...
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Do collisions of stars still undergoing fusion reactions produce gravitational waves?
When studying gravitational wave sources, we just consider BNS, NSBH, and BBH systems since their inspiraling and collisions can produce detectable graviational waves. Also according to the paper &...
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Does the mass-luminosity relation work for brown dwarfs?
There is a mass-luminosity relationship of the form $L \propto M^a$, where $a = 3.5$, that is is applicable to main-sequence stars. Is there a similar relationship that holds for brown dwarfs?
user47732
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What is the contribution of star-produced axions to the dark matter budget of the Milky Way?
I try to follow the discussion of axions since Peccei, Quinn, Wilzcek and Weinberg. What I still don't understand is how much the speculated stellar production of axions could add to the galactic dark ...
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What kind of nebula was the Sun formed from?
I was just wondering what type of nebula did the Sun form from because mainly there are 5 categories: emission nebulae, reflection nebulae, dark nebulae, planetary nebulae, and supernova remnants, so ...
user47732
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Transit probability calculation
I'm trying to calculate the transit probability for a planet orbiting a star. Here's what I know:
Mass of planet: 1.8 Jupiter masses
Period: 2.2047 days (0.0332 years)
inclination, i: 80.8 degrees
...
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How to show that $P_c=(9GM^2)/(14\pi R^4)$ from equation of hydrostatic equilibrium
I need to show that $$P_c=\frac {9GM^2}{14\pi R^4}$$
from the equation of hydrostatic equilibrium: $\frac {dP}{dr}=-\frac{GM\rho}{r^2}$
in the exercise before, we show that $\rho_c=\frac {6M}{5 \pi R^...
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What stars are brighter then any star nearer to the south celestial pole [closed]
What stars are brighter (apparent magnitude) then any star nearer to the south celestial pole?
I know that there’s no bright star within a few degrees of the south celestial pole.
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If Earth's rotational speed is zero at the North Pole, why do stars still have apparent motion?
The apparent motion of stars (and other objects) results from Earth's spin on its axis, hence the rising and setting of some stars, and the circumpolar nature of others.
If the ground is not moving ...
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How are the masses of solitary stars weighed?
How are the masses of solitary stars weighed?
With binary stars you can measure the pull each applies to the other, but that isn't an option with solitary stars.
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Sky density of milky-way stars vs external galaxies
I am interested to know if any particular slice of sky contains more galaxies or more stars (in the milky way, although would be interested to factor in extra-galactic stars, and even rogue planets)
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Star identifier needed
Like other apps such as PeakVisor for identifying mountains, I was hoping there was an app with which I could upload a photo to identify stars in the night sky. I’m not finding one so thought I’d try ...
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Which star has a higher effective temperature, a red dwarf or a red giant?
According to the Hertzsprung-Russell diagram, they would roughly have the same temperature, but I've read in bibliography that the surface temperature of the red giant is about 5000K
and the one of ...
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A what distance could we see the Sun?
How far away can we see the Sun with the naked eye?
How far with an amateur telescope? And with the James Webb telescope?
In my own calculations the Sun would appear magnitude 6 at 56 ly, magnitude 8 (...
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What is the average and the median mass and luminosity of a star?
I've heard in many places that the Sun is an average star, but in Wikipedia it says that about 75% of stars are M-type stars that are way less massive and fainter that the Sun. So how massive and ...
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What is it like to see a brown dwarf turn into a star?
Brown dwarfs/failed stars can actually become stars, if they exceed a mass limit of about 80 Jupiter masses. This is when the internal pressure and temperature at the core become high enough to ...
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How can I calculate evolutionary timescales of low mass stars?
How can I calculate how long a star of a given mass will spend on an evolutionary branch before evolving off it?
I'm thinking about the evolution of low mass stars from the subgiant branch to the red ...
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How do I calculate the flux density of a substellar object?
I am currently trying to generate photometric passband colors for brown dwarfs and planets generated through MESA (Modules for Experiments in Stellar Astrophysics). I believe I understand the ...
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Are all T Tauris on the Hayashi track?
Reading the definitions of T Tauri stars and the Hayashi track one can gather that:
T Tauri stars are pre-main-sequence stars in the process of contracting to the main sequence along the Hayashi ...
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How does one convert between Modified Julian Date (MJD) and a standard (mm/dd/yr, hr:mm:ss)
I looked online and couldn't see an actual formula or anything, so I figured I'd ask here.
If I had an MJD like the following: 59145.6678
How would I convert that to a month, day, and year with the ...
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"Opacity" in red dwarfs
One day, while researching on blue dwarfs in Wikipedia, I stumbled across something that I cannot understand:
Rather than expanding, however, red dwarfs with less than 0.25 solar
masses are predicted ...
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What would our Sun look like from other solar systems?
I came across an article that shows how the Sun looks from other planets of our solar system.
Now I am wondering, how does our Sun look from an exoplanet? I am guessing it must be looking like a 'star'...
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Why can four-eight "rays" be seen around all stars in astronomy photographs from the Hubble Space telescope? [duplicate]
In famous astronomy photographs from the Hubble Space telescope such as the Pillars of Creation, each star has four rectilinear "rays" projecting out in the intercardinal directions, and ...
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Stars being eclipsed by planets
I would like to figure out if any of the solar system planets have ever eclipsed a particular star (i.e. crossed the line of sight from Earth to the star) or will eclipse it in the future. Is that ...
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Age of Alpha Piscium B
According to https://en.wikipedia.org/wiki/Alpha_Piscium, the age of Piscium B is 331 Myr and the Surface Gravity of 4.01 ± 0.14 it cites the link :- https://academic.oup.com/mnras/article/483/2/...
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English Meaning for Abreviations (Easy Question)
I see a lot of publications where they use "code"/abbreviations but don't give the Laymans equivalents. Take https://academic.oup.com/view-large/127773013 from https://academic.oup.com/...
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Does the orbital velocity of a planet affect its escape velocity from the planet surfaces?
I'm trying to write a hard sci-fi novel with good accuracy, but when it comes to astronomy, I'm a total amateur.
Here's my fictional planet that orbit a black hole information:
Star Mass = 10000 Solar ...
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Are there any (rough) estimates of stars' orbits around the galaxy?
The Sun orbits approximately 26,000 light years away from the galactic center. Are there any other known orbital parameters relative to the galactic plane for the Sun and other stars up to some ...
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How bright will Alpha Centauri A be from Earth when it becomes a red giant?
As of right now, both stars from Alpha Centauri are in their main sequence stages, but eventually Alpha Centauri A is going to quickly expand in a matter of time, and I’m pretty sure its luminosity is ...
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