Stars Definition and 878 Threads

I just logged this on the biblio thread. This is in case there are questions, or things people want to discuss. http://arxiv.org/abs/1401.6562 Planck stars Carlo Rovelli, Francesca Vidotto (Submitted on 25 Jan 2014) A star that collapses gravitationally can reach a further stage of its...

Do less bright stars have redder spectrum?

Hello, Can anyone confirm or, refute and correct the following statements? The volume of our galaxy, is roughly 8 trillion cubic light years. The combined volume of all the stars in our galaxy only equals one cubic light year. Thanks for any help you can provide! Rusty

This paper, http://arxiv.org/abs/1312.5320, discusses the possible detection of galaxies almost entirely consisting of pop III stars.

So how much denser than is a neutron star than an atom? Is it called a neutron star because electron's orbital effect no longer exists/acts the same, so as to no longer cause 99.99% of everything to be space?

This paper, http://arxiv.org/abs/1311.6806, discusses Kepler mission results. The authors deduce that 5.7% of sun-like stars have an Earth sized planet orbiting in the habitable zone. That is a shockingly large number, IMO. Considering there are an estimated 26384 class G class stars within 324...

Hello , it is said that at the center of planets and stars there is zero gravity because , assuming spherical geometry, the gravity from all sides comes together and cancels out in the middle and everything that is in close approximation to it. Now that said I also read that the pressure at sun...

Folks, Please don't flame me for this as it is probably already answered somewhere. How does one estimate the number of stars in a 500pc^3 which have a range of 10^-2 to 0.1 Lsun? I am not a maths head, so simple answer that would have the formula would be great. Thanks

Homework Statement Two double stars of the same mass as the sun rotate about their common center of mass. Their separation is 4 light years. What is their period of revolution? Homework Equations Lagranian = T - U = \mu\dot{r}^{2}/2 + \vec{L}^{2}/2\mu r^{2} - Gm_{1}m_{2}/r F = ma =...

Simply put, either by chance or a suicidal type-III Civilization, 2 neutron stars, or a neutron star an a large-ish main sequence star are thrown at each other and fall STRAIGHT into each other. What happens? Does the ~1.4 C Newtonian impact speed result in them getting blown up and releasing...

Neutrons are neutral (obviously). I thought only charged particles could be magnetic. So how are neutron stars magnetic? Thanks for any help.

Astronomy homework question -- stars emitting in infrared Dear All, Hello! This is my first post. I am taking a distribution introductory astronomy course (low on math) and am having trouble with this question: Which object emits more intense infrared radiation: _ the Earth _ the Sun...

Hello everybody! I read that because of about 4 min difference between sidereal day and solar day, at the end of a year each star has rotated 366.25 times(apparently). I looked up in software such as Starrynight, the position of for example Sirius at 1 September of 2013, 2014, 2015 and so on. I...

Isn't the reason the sky isn't bright at night ,due to all the stars, because the fact the stars aren't bright enough to be seen by the naked eye after a certain distance? So it doesn't necessarily depend on the fact the universe doesn't have to be infinite or expanding? I know the intensity of...

Hey, I am an undergraduate physics & astronomy student. I am looking for a good research topic to work on for this semester. I have access to a .5 m telescope in Louisville, Ky (38 deg N), a .5 m telescope, and possibly another with a built in spectroscopy as well as photometry capabilities...

Light from distant stars is doppler shifted. Is the measured speed of light from these stars lower than the speed of light from the sun? Would one expect the permativitity of free space to vary over the universe?

Good article about Quark stars: http://www.nanowerk.com/news2/space/newsid=31543.php of course, the title instantly makes me think, "Piccard would not approve!" :biggrin:

Hello everybody I am a first year student and I have a question about stars' masses. I've been thinking about, what happens to a star's mass cause of the high speeds of the particles there. Do we consider the 'extra' mass, 'caused' by relativity (really high speed particles are heavier than...

Hi, One can register waves of light. Is there anything known different then stars where we receive information from? Say black holes? I really guess.

I've been comparing light as particles and waves in outer space when it occurred to me, if you throw two rocks of equal weight into a pool side by side the waves created will cancel out. Do stars In space effect each other in this way?

Is it possible for some brown dwarves to be more massive than some stars?

I'm working on a video game set in space, and I'd like my portrayal of the galaxy to be as scientifically accurate as is feasible. I've been looking into metallicity functions, but I can't make any sense of what I'm seeing, and I don't even know where to start on the subject of algorithms for...

It is often quoted that, when we see stars from Earth through, for example, a telescope, we are not seeing them as they are now, but how they were millions of years ago (because the travel of light is not instantaneous). However, say if I take a picture of a star from Earth, then jump into a...

If there are so many galaxies in the universe,Why don't wee see a night sky with full of light(from the galaxies or stars)

Obviously if you looked at one it would appear white as it's so bright and stars are black bodies so emit all over the spectrum (correct me if I'm wrong). But as the sun is a yellow star, it looks yellow around it (unless that's the atmosphere of Earth getting rid of blue?) and has a yellow...

Homework Statement In a certain binary-star system, each star has the same mass which is 7.5 times of that of the Sun, and they revolve about their center of mass. The distance between them is the 7.5 times the distance between Earth and the Sun. What is their period of revolution in years...

This whole "we're made from stars" thing. I keep coming across internet memes that say all the elements (except H and He) were created from stars, and therefore, humans are the product of stars. Every atom in our body came from a star billions of years ago. I never gave it a second thought...

I think space-time exerts a pressure on substance and it makes star to transorm black hole.I think this can be possible becuse we know that space-time is something which it can be tiltled and it can creates virtual matters.Space-time is real thing.So Can be space-time exert pressure on substance ?

1st post here - new to the forums - sorry if this is a stupid question.I was thinking, if the universe is approximately 98% hydrogen, you would think the matter a black hole consumes would be mostly hydrogen. So you have a black hole, it's consuming a ton of hydrogen, squeezing and condensing...

Phase of the star's death ,when star's fuel ended,we know that it will collapse into itself Why do stars collapse in on itself ? How to collapse in on itself ? Although the end of the fuel in the star,how to collapse in on itself? Because inside the star there is no...

Dear all, I'm starting to study neutron star accretion and a lot of physical phoenomena coming from different scales come along and a consistent picture is frankly hard to grasp. But for now, a real mind boggling question can't exit my mind. Are Neutron stars, as a whole Quantum, or...

If two stars, each moving away from each other faster than the speed of light, how would the light behave? Let me add more detail, if you have two stars a light-year away from each other and "off" and then accelerated both of them in opposite directions traveling at say .60c and identically...

I wonder if some old stars will become invisible to our eyes after a while because of the redshift? Since they get further away from earth, maybe we won't receive their radiation in visible light any more? I'm talking about stars that are not obscured by any other objects or dust, which you...

Homework Statement http://postimage.org/image/7rgmo1527/ How is the speed decreasing and acceleration decreasing in this problem? Homework Equations Kepler's Laws? The Attempt at a Solution I remember in lecture my professor was saying something along the lines of objects...

Homework Statement The number of stars around the Sun, within a distance of 17 ly, is 75. The number of galaxies in the local group, within a distance of 4.0 x106 ly from the Sun, is 26. Calculate the average popluation density, per ly3, of stars and galaxies. Homework EquationsThe Attempt...

What percentage of stars become black holes? I tried to find this information through Google searching and the only thing I could find was a statement that said less that 1 in 1,000 stars in our Milky Way galaxy have enough mAss to become a black hole.

Having recently read two books (Just Six Numbers by Martin Rees and The Fallacy of Fine-Tuning by Victor Stenger) I am confused on one issue. Assuming a multiverse, what is the probability that stars and galaxies would form in a universe. Stenger would say it is high but Rees would say it is...

QUESTION A star of bolometric luminosity L at a distance r will exhibit a bolometric energy flux F given by F = L/4πr2 in the absence of obscurity. A. Assume that all stars have the same bolometric luminosity L and that stars are uniformly distributed in space with a number density n...

Homework Statement A binary system consists of two stars of equal mass m orbiting each other in a circular orbit under the influence of gravitational forces. The period of the orbit is τ . At t = 0, the motion is stopped and the stars are allowed to fall towards each other. After what time t...

I just posted a question to ask for help on the Calculus & Analysis section to determine how fast planets go into stars. I should give a little background, in addition to pointing you to my latest two short papers: http://arxiv.org/abs/1301.4229 and http://arxiv.org/abs/1211.1984 I have...

I am an astronomer with a research question: I want to evolve this equation for planet distribution: \frac{{\operatorname{d}}f(P)}{{\operatorname{d} \operatorname{log}}{P}}= k_P P^\beta \left(1-e^{-(P/P_0)^\gamma }\right) as a function of period ``P'', by using an equation for change of P. I...

how can you use the angle to determine the distance if you don't know the motion of the star itself. is it by observing the star from the same point in two different years and then subtracting off this effect?

Wouldn't the Redshift result in decreased heat from far distant stars, resulting in an equilibirum temperature, much lower than the average star?

Homework Statement About neutron stars we can say that: a) They are newborn stars b) They are generated when a Solar-type star dies c) They are generated when a very massive star dies d) They are in the main sequence Homework Equations None. The Attempt at a Solution I'm...

Homework Statement Given pulsation period in days, (surface temperature) and mass of an RR Lyra variable star. How do you find luminosity? Homework Equations The relevant equations seem to be for finding the luminosity of Cepheids... there are no equations for Lyrae... Other than, absolute...

Hi There Just came across the idea that stars heat up when they lose energy and have been thinking about why this might be... below is my best guess: Stars heat up when they lose energy because this implies that the ions that compose the star each experience a reduction in their kinetic...

Is there a large database that contains, for many stars, their estimated metallicities as well as their redshifts (or, equivalently, distances from us) and masses? What I'm trying to do is estimate the chemical abundances at different ages of the universe. If I have the metallicity of a star...

how will the pattern of stars in the milky way change as the galaxy rotates, will they be rotated in some direction or drifted or something? and what is the timescale for that to happen? Thanks!

I have always been wondering how in an active star the H/He fusion cycle is "managed" for lack of a better word, a little like a logistical analogy really. Specifically: i) Where in the star is the yet-to-be-fused H 'stored'? ii) Where in the star is the He result of fusion 'stored'...

I am studying for my undergraduate Astrophysics module and the lectures notes say that that all abundances are measured relative, in terms of H = 12.00 by mass or number of atoms. Is this correct? I thought it was all based off of Carbon = 12. Am I missing something?