A star is an astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but due to their immense distance from Earth they appear as fixed points of light in the sky. The most prominent stars are grouped into constellations and asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated 1022 to 1024 stars, but most are invisible to the naked eye from Earth, including all individual stars outside our galaxy, the Milky Way.
A star's life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. The total mass of a star is the main factor that determines its evolution and eventual fate. For most of its active life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space. At the end of a star's lifetime, its core becomes a stellar remnant: a white dwarf, a neutron star, or, if it is sufficiently massive, a black hole.
Almost all naturally occurring elements heavier than lithium are created by stellar nucleosynthesis in stars or their remnants. Chemically enriched material is returned to the interstellar medium by stellar mass loss or supernova explosions and then recycled into new stars. Astronomers can determine stellar properties including mass, age, metallicity (chemical composition), variability, distance, and motion through space by carrying out observations of a star's apparent brightness, spectrum, and changes in its position on the sky over time.
Stars can form orbital systems with other astronomical objects, as in the case of planetary systems and star systems with two or more stars. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy.
Homework Statement
Compute the speeds (in km s^-1) of S0-2 and S0-16 at pericenter and apocenter.
star S0-2: period P = 15:8 yr, semimajor axis a = 1025 AU, and
eccentricity e = 0:880;
Homework Equations
Vp=((1+e)u)/(1-e)a))^1/2 va=((1-e)u)/(1+e)a))^1/2
u=(m1m2)/m1+m2
The...
Homework Statement
If a star emits the same intensity of radiation at all visible wavelengths, what will be its
apparent color at the Earth’s surface?
Homework Equations
No equations...
The Attempt at a Solution
I realize that a horizontal line would occur through the visible...
Homework Statement
A) How many W does 1 kg of the sun’s interior produce via nuclear reactions, on average? Compare the sun with a carbattery, which typically produces 190 W/kg. Which body wins?
B) Estimating the time the two objects are providing their respective power, compare the energy in...
I'm toying with the idea of making a little 2D space orbiter game so I've implemented Newton's universal gravity law into this little app. It works really well, even.
The problem I'm having is when I want to create an asteroid-belt. I spawn little asteroids randomly around an area around the...
This question has been bugging me... I've rephrased the question a bit so it shouldn't require much astrophysics knowledge to understand, just a bit of regular physics.
Consider a binary star system. By doing some geometry based on visual observations of the positions of the two stars over...
Homework Statement
The Starship Enterprise returns from warp drive to ordinary space with a forward speed of 56km/s. To the crew's great surprise, a Klingon ship is 120m directly ahead, traveling in the same direction at a mere 24km/s. Without evasive action, the Enterprise will overtake and...
Hello,
I'm doing a project on proving the existence of black holes. I am using Sgr-A as a test subject and am after the data set for the orbit of the star S2 around it so I can do some of my own calculations on it. Does anyone know where i might be able to obtain these?
When did humanity realize that the Sun is similar to the night-time stars? I can find no reference to this in Wikipedia or anywhere else.
It seems that ancient man thought that the Sun was unique of it's kind (similar to how we perceived the Moon before Galileo observed Jupiter in his...
Very quick question PLEASE - Star Connection!
Homework Statement
i'm just working on some questions on power engineering and there's a question on star connections. the wording is a bit funny - wondering if can get some clarification please.
"a three phase load is composed of three...
I'm trying to find some information about models of star formation (just out of curiosity). I only have a basic knowledge of text-book physics and calc, so it's hard to get started. In particular, I'd like to know how the theory is tested. The only prediction of Nebula theory that I can think...
Just watch the 8th star treck movie,and at the beggining a champagne bottle smashes into the side of a newly made neterprise.
what I am wondering is,as its in a vacuum would the pressure inside the bottle pop the cork out,or is the cork in tightly enough that it wouldn't pop? (lets say the...
Maybe this is stupid question, but I am not sure how to get the diameter of the star cluster, I assume from the RA and Dec. I googled it and tried to come with a realtion between the RA , Dec and Diameter from Andrea's proposal but couldn't figure the correct answer
This is all I find (see...
Homework Statement
A spherical star of uniform density p and radius R is formed by the condensation of the interstellar dust from large distance due to gravitational forces. Find the energy change that occurs at some intermediate stage as the radius increases from r to r+dr
Hence derive an...
I'm working on trying to determine a formula that can model the density of the sun.
density:
\rho = m/v
the volume of a three dimensional figure is b*h
therefore: v of cylinder = Area of a circle * h (delta r = h)
v=\piR2\Deltar
therefore: \rho = (\Deltam)/(\piR2\Deltar)
If this...
Scientists find most massive star ever discovered,
Like Charlie on 2 1/2 men, sounds like burning the candle at both ends...
http://news.yahoo.com/s/ap/20100721/ap_on_sc/eu_most_massive_star
Saw a reaalllyy bright star-looking object in the sky tonight
after looking online, I'm thinking it was Venus. That what all the articles online are leading me to believe.
so... Has anyone else seen it? it looks amazing to be honest. I really wish I had a telescope.
Firstly, I would like to say hello to everyone as this is my first post.
I am an artist working a personal project that will be a visual investigation into the effects of a collision between a Neutron Star and Earth.
The star would have a fully collapsed core at 1.5 solar masses (maybe...
How do I get radial velocity of a star given a single body orbiting it in a 2-body system?
I have the mass of both objects and for the second object it's eccentricity. Assume everything else is default or zero like the mean eccentricity.
I compute the barycenter between the star and...
We consider two stars which initially were at rest with each other, and were gravitationally influencing each other. We assume a kind of gravitation force which propagates at light speed. Now we give equal velocity (in relatively opposite direction) to both stars. Since gravity is propagated at...
Reading from The Astrophysics Spectator:
http://www.astrophysicsspectator.com/topics/supernovae/SupernovaeCoreCollapse.html
"When a stellar core collapses, its high density spurs the creation of thermal neutrinos through a variety of processes. The core itself is not transparent to...
I saw this on another site.
The star Betelgeuse going supernova soon?
I was talking to my son last week (he works on Mauna Kea), and he mentioned some new observations (that will no doubt get published eventually) of "Beetlejuice"; it's no longer round. This is a huge star, and when it...
I have a (probably elementary) question about the end of a massive star. I know that the two issues are a neutron star and a black hole, depending on the remaining mass of the core.
In as much as I understand things, a type II supernova results from the sudden halting of the collapse of the...
For my vector calc class we were given an assingment to do some stuff with a binary star system. You might note the lack of vectors and the lack of calc; this is because I am just having an issue with the setup. I am sure I can get the rest without assistance.
We are given the two stars of...
Hi
Homework Statement
As the sun evolved to the main sequence it contracted under gravity and its internal temperature changed from 3E4 K to 6E6 K. Assuming the sun is fully ionised at these temperatures estimate the energy radiated during this phase, stating your assumptions.
Homework...
Homework Statement
Two individual stars in a binary system (m1=mo, m2=2mo) are in circular orbit about their common centre of mass and are separated by a distance ro. At some stage, the more massive star explodes - resulting in the two stars having equal mass after the explosion...
Homework Statement
If a neutron star were bright enough to see its surface with a telescope, we'd be able to see not just the hemisphere facing toward us but also part of the far hemisphere. Explain why and estimate the latitude above which the far side could be seen.
Homework Equations...
I was sitting with friends on the street, and we saw what appeared to be a star that was zigzagging. Of course, it wasn't a star. The zig-zagging wasn't in straight lines or anything, it was just moving, faster than any plane, it was very far away (just appeared as a pinpoint of light), and...
http://spaceflightnow.com/news/n0210/11planet/
This is the only discovered planetary orbit around a close binary star that I know about.
I have some general questions about planetary orbits around or within close binary systems or even the further apart binary star formations or triples...
Hi,
Let's say that you had the following information (age with errors, U-B, B-V, V) for 100 star clusters, what would you do with it? What can it be useful for?
Just wondering...
Homework Statement
Iota Draconis is the eighth brightest star in the constellation Draco. Observations show that a planet, with an orbital period of 1.50 y, is orbiting this star. The mass of Iota Draconis is 1.05MSun.
(a) Estimate the size (in AU) of the semimajor axis of this planet's...
Imagine that a star could be composed entirely of protons so that Thomson scattering by protons dominated the stellar opacity. How luminous, in L_{\odot}, would the star have to be to blow itself apart by radiation pressure?
I know that the luminosity has to be greater than the eddington...
Homework Statement
The mass of a star is 1.370×1031 kg and it performs one rotation in 38.10 day. Find its new period (in days) if the diameter suddenly shrinks to 0.330 times its present size. Assume a uniform mass distribution before and after.
Homework Equations
Ii * Wi = If * Wf...
has anyone ever read it? I'm reading it now, and sometimes I don't understand some of it (I'm in 8th grade), but it keeps me on my toes. Anyone else ever read it, and if so what do you think of it?
Homework Statement
A planet of mass 8.01 MJ (MJ = Jupiter's mass is known) has been discovered orbiting the star HD 168443 . HD 168443 is an G6 IV star of L = 2.09 Lsun and T = 5300 K about 37.9 pc from the Earth in the constellation Serpens Cauda. The planet, so far known only as HD 168443b...
star is created from a cluster of gas. but how is this process take place? in the sense that what is driving the gas and dust to form a star? as only massive object can experience gravity. only after a star is formed, then gravity will come into play. but my question is? before gravity come into...
Apparently, in the early universe, stars were massive - ranging up to about 500 solar masses. Furthermore the metallicity (elements other than H, He) in the early universe was effectively zero with only hydrogen, helium and trace amounts of lithium. Apparently, stars could reach large masses...
Is there such a thing as a black star? Not black hole.
I read something from a national geographic magazine a few months back that was about an astronomical object. It was all black on the outside, emitted darkness instead of light, and it contained some water. It was some new discovery or...
Homework Statement
There is no general analytical solution for the motion of a 3-body gravitational system. However, there do exist analytical solutions for very special initial conditions. The diagram below shows three stars, each of mass m, which move in the plane of the page along a circle...
Homework Statement
Determine the dip in magnitudes and flux in the optical light curve caused by the planet in front of the star if the planet orbits at 0.1,1 and 5 AU:
The star is a solar type star and the mass of both the planet and star are known as are their radii:
The observer is 10pc...
I hear that large telescopes can resolve the Andromeda galaxy into individual stars. Is it possible to do the same for galaxies outside our local group? Also, have we observed any stars which sit in deep inter-galactic space, far from any galaxies?
Hi
When I was a kid, the largest telescope was Mt Palomar, a little over 5 meter diameter mirror. In spite of its large size, I always read that stars appeared as points of light through the scope if it were used visually, i.e. stars are too small and too distant to appear as disks.
However...
"Artificial Telekinesis" - The Star Wars Force Trainer
Seems to be legit. I have been aware of work with this technology, but I think this is the first commercial product that I've seen.
https://www.youtube.com/watch?v=LJbIGJrQK84
In fact the toy seems to have been around for a time...