Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

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60 views

Are these stars in MASCOT image of Ryugu?

Are these stars in this MASCOT image of Ryugu? Larger image: https://www.sciencealert.com/images/2019-08/processed/RocksOfRyuguStranglyFamiliar_1024.jpg They seem too bright to be stars (if the ...
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1answer
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Brightest most colorful star in eastern morning sky not near any constellations; rises about 4 or 5 am?

I have been believing this is Saturn, but perhaps Antares instead? It is so colorful it shines blue, red, green and white. It is largest in sky in the East before dawn rises about 4 or 5 AM, seen ...
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Is it a star or something else [duplicate]

I was lying down with my face up looking at the stars. Then I saw this star moving: it was moving at one direction (just like airplane) it's light was not blinking, just exactly as other stars both ...
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Is it possible to determine an observer's position on Earth from a photo of the night sky and the time of the shot?

To my knowledge, this question can be related to celestial navigation on one hand and to attitude (or orientation) determination from stars direction on the other hand. However the combination of this ...
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1answer
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In System KIC 9246715, How Far Does One Star Orbit the Other?

I was going to ask if it's physically possible for one red giant to orbit another, but fortunately, I have just found such a thing--a red giant binary system known only as KIC 9246715. In this ...
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1answer
41 views

Maxwell stress contribution to $\nabla \cdot \mathbf{P}$ in the Navier-Stokes equation for fluid in stars

I was reading through the following extract outlining how the Maxwell stress contributes to the $\nabla \cdot \mathbf{P}$ term of the Navier-Stokes equation for fluids in a star. Here $\mathbf{P}$ is ...
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1answer
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Why is our Sun hotter than UY Scuti?

As Wikipedia says the surface temperature of UY Scuti is 3,365 K and the sun is 5,778 K Why is the Sun hotter than a supergiant star like UY Scuti?
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Apparent Magnitude / Apparent Brightness relationship help

I'm a high-school student that is currently working on a project that describes, using mathematical notation and explanation, how scientists can find the values of each of the properties of stars, ...
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1answer
137 views

Could anything consume a small black hole?

Whenever I read about black holes, it is normally involving how they devour anything that comes too close... regardless of how big anything is. But what if it were a really small black hole vs ...
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1answer
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How to interpret error of absolute magnitude of a star given data from wikipedia?

This Wikipedia page contains information about the star Spica in the rightmost table. A small snapshot of this table is below. In this table, the absolute magnitude is given as ...
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Black hole's gravity

Is gravity relative to volume, or size of an object? Since a black hole is a massive star that collapses on its weight, how comes the same sun's mass, when it becomes a black hole, provides gravity ...
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What Would Be the Maximum and Minimum Luminosities of a G-Type Main-Sequence Star?

So I just found the Habitable Zones in Multiple Star Systems interactive website, where I can create a habitable zone out of multiple stars using the temperature, luminosity, mass and position of each ...
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70 views

How to create unique 3d star maps?

I have been trying to create a calculator which finds the distance between two stars that the user chooses. But I'm having a hard time visualizing where these stars are in real space. Do you know of ...
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1answer
43 views

Turn celestial coordinates into light years

I have a question about celestial coordinates. I have been working on a calculator that takes in different stars and tells you how far apart they are, and their coordinates (x, y, z). But I didn't ...
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220 views

Is there a way to factor age into the mass-luminosity relationship for stars?

I'm wondering if there's a way to formulate the luminosity of a star not only as a function of mass, but of age, too, and if so, what the formula for luminosity would look like. In the case of the Sun ...
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Why do astronomers use the equatorial coordinate system that moves, instead of one based on fixed, distant stars?

As an outsider to the field, I am surprised to learn that astronomers commonly use the equatorial coordinate system, in which fixed stars are not actually fixed. Isn't that making life harder than it ...
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What would happen if a Sun-like star were to consume a Jupiter-like planet?

A substantial number of discovered exoplanet systems are likely contain more than one gas giant with distances far closer to the star than in our solar system. It is known that in solar system ...
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Which star / galaxy is moving away from us the fastest?

I know that we have measured the rate a lot of stars and galaxies move away from us using the doppler shift, and I know that the further a star / galaxy is the faster they accelerate away from us due ...
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Stars that don't fit $L=4\pi R^{2}\sigma T^{4}$?

When calculating luminosity/radius/temperature for several stars, I've noticed that while the majority of stars conform to the luminosity relationship $L=4\pi R^{2}\sigma T^{4}$, there are a few that ...
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1answer
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What does cz mean?

Take DS Geminorum for example, it has a cz of -2.33 [2.96] My question is what does cz mean, what does is represent? and what does the value in the brackets mean? http://simbad.u-strasbg.fr/simbad/...
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Saw moving stars in the sky [duplicate]

So I was out with my friends at a bonfire and we decided to sit down and star gaze, my other friend pointed out a star that looked to be moving and we all followed it with our eyes and t was smaller ...
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Stars readjusting themselves in the sky [duplicate]

I had a meeting in the evening and thought of grabbing a snack before that. I stepped out of the office along with a colleague. He was on his phone and I was simply staring at the sky wishing it would ...
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Does the density in the core of a “higher mass” star stay generally constant while it evolves on the MS?

We know the CNO cycle produces the majority of energy production in a "higher mass star" of approx. over 2 solar masses and the core is convective due to the large temperature gradient. My professor ...
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Are horizontal branch stars fully convective?

I know that RR Lyrae stars are convective (this is suspected to be part of the cause of the Blazhko effect), but I would like to know more generally: Are RR Lyrae fully convective? Are all HB stars ...
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300 views

Hottest Possible Hydrogen-Fusing Stars

I guess this is more a question about stellar models than anything else. I was wondering what is predicted to be the hottest possible stars that would still be hydrogen-burning. What complicates ...
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Theoretical values of radius and mass of O9.5 II star

Where to find please theoretical values of radius and mass of O9.5 II star? I mean something like in this article. However, there are only O I, O III and O V stars in this article.
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How do we measure distance in space?

I know that you can calculate the distance to another star for example, by using the phenomenon redshift to determine how much it has redshifted because of the expansion of the universe. But how do ...
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295 views

Can a black hole “supernova”?

In layman terms: nothing ever escapes the pull of a black hole, not even light when a super massive star reaches the end of it's life you get a supernova sometimes the "remains" of these stars can ...
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really fast moving star-like light [duplicate]

I don't know ANYTHING about astronomy but I know what I saw and 2 of my siblings saw it too. I initially thought it was a shooting star, but a Google search quickly made it clear that it wasn't. it ...
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Ludwig's star distance

Mizar and Alcor, each about 83 light-years away (in fact Mizar presents system of four stars and Alcor is binary system. It is not yet known if those 6 stars presents one or two star systems. In ...
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1answer
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Given a star's mass, age, and composition, how do I calculate the rest of its properties?

If I'm given a star's starting mass, starting composition (metallicity), and its current age, How do I calculate the star's luminosity, current mass, and radius? I want to know how to do this for any ...
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1answer
55 views

How is stellar mass of a galaxy obtained?

I believe there is a difference between the mass calculated using the orbital speed and the stellar mass of the galaxy. So how is the stellar mass calculated? Thank you :)
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On a Hertzsprung-Russell diagram, why is the main-sequence line squiggly?

When I look at a Hertzsprung-Russell diagram, I'm able to see a main-sequence line from the most luminous main-sequence stars at the top left to the dimmest main-sequence stars at the bottom right. ...
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1answer
37 views

How do I find stars within milky way using galactic latitude and longitude

I have data that contains galactic latitude and longitude of stars. I have to determine all the stars that are within our milky way. How do I find it?
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Why doesn't it hurt to look at stars?

If I stare at the sun, it's bright and blinding. However, if I look at a star in the sky, it doesn't hurt. What causes this loss of energy that would otherwise damage one's eyes?
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What is the most mass that matter likely to form?

If we plot graph between accumulate of forming mass (y-axis) and mass (x-axis), where is the maximum ? There is a story how I get this question. It start when I think about question "Is our sun is ...
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1answer
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What limits the use of the H-R diagram to measure distance (main sequence fitting), what distances is it useful for?

Is it only possible to measure objects that form around the same time? Is it possible to measure clusters from distant galaxies other than our own?
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1answer
224 views

How to differentiate elements that have same spectral lines in a star?

Suppose that iron and calcium have a spectral line with the same wavelength. How would you determine which element is present in the atmosphere of a star if you found this line in its spectrum?
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1answer
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Eddington luminosity in various plasmas

So I know that the Eddington luminosity is given by: $L_{Eddington} = 4\pi GMc/\kappa$. I want to calculate this luminosity for a plasma of purely ionized helium, as well as for an electron-...
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239 views

Can a star fall in a super massive black hole without getting destroyed?

This is the first of many similar questions I have to build up to a specific question or scenario that I want to explore and find an answer to.
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115 views

Why does the sun have a convection layer and a radiation layer?

Why is the outer section of the sun convective but the inner section stable and only radiative? They are both made up of the same kind of matter, both heated by the core.
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1answer
147 views

Is there a database of all known star names/identifiers?

I am looking for a list of all known identifiers used for stars. I'm not sure on the terminology. While I do want the "proper names", I also want whatever identifier is used for each star detected, ...
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1answer
94 views

Is there a theoretical minimum mass main sequence star that can become a red giant?

Wikipedia's Red Giant page says they range in mass from 0.3 to 0.8 solar masses. Which corresponds to an initial mass of a bit less than 1 solar mass, about 0.8 or so, if I was to estimate and a few ...
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Are red giants stationary or do they move? [closed]

A friend and I are having a friendly chat about this. They are stars so I'm claiming they still move in orbit.
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Why does star formation cease?

The universe is expected to have a time when star formation slowly ceases. However, this seems bizarre as there is always an abundant amount of matter in the Universe. Massive amounts of hydrogen ...
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1answer
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Do astronomers have any idea what percentage of our galaxy’s stars move in retrograde orbits?

I recently noticed that none of the planets in our solar system orbit the Sun in a retrograde direction. This is likely because they formed moving in the same direction as the planetary disk did in ...
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3answers
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Are white dwarfs the ones always absorbing mass from a companion?

It seems to me every time I see stellar remnant binary systems where there is a white dwarf and another star or something, it appears that the white dwarf always pulls mass from the star. What if the ...
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Can Earth be ejected out of the solar system this way?

I found this image of what maybe a model of our solar system. Without a credible source I'm not sure I am looking at a star or black hole that comes close to our solar system and how it could throw ...
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1answer
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Is it possible that in the Local Interstellar Cloud there are undetected stars?

The Local Interstellar Cloud is supposed to be around 30 light years large. Is it possible that in this region there are stars which are undetected? I would have thought that it wasn't possible, but ...
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97 views

When a rogue brown dwarf star hits a white dwarf star, will the collision at most cause a nova? [closed]

When a rogue brown dwarf star hits a white dwarf star, will the collision at most cause a nova? Or can the explosion be heavier?