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.
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Star mass affects event horizons diameter.But we know that Black hole's foundation is singularity so we can understand that singularity affects event horizon diameter.
Example:Imagine there are two stars, first star mass is 5 star mass second one is 7 star mass...
i was just thinking , a planet comes close to a very massive star but doesn't collide .how can i calculate the its angular deflection.?
i can calculate the velocity afterwards the deflection(given the initial and final perpendicular distances of its course from center of the star) using...
I know that our solar system and sun evolved from a nebula of a giant star.. but what happened to the remaining of the star.. entire star cannot go boom.! at least some remaining portion of the primordial star should have existed in the form of a neutron star or a white dwarf. If it existed what...
Homework Statement
Angular separation of stars 1.5 arcsecs
Parallax 0.0050 arcsecs
Apparent vis magnitude 2.5 (star a) and 7.5 (star b)
The two stars may be in orbit about each other in a binary system, or may be separate stars viewed by chance in almost the same direction in the sky.
(i)...
Hi! I am currently interested in working on a simulator that emulates the creation of a star in c++. Basically, I'm thinking of generating a large number of particles (protons) fairly close to each other and apply gravitational and electro-magnetic force to them, and then see what happens. It...
Can anyone point me towards a listing of common star names for the FK5?
I've been going through Wikipedia, one star at a time compiling common name, constellation and greek letter for the FK5 and I have lost my enthusiasm after a hundred or so stars.
Surely someone (with more fortitude)...
My gut feeling says this is a bad idea, but the star wars crazed kid in my is giggy!
http://movies.yahoo.com/blogs/movie-talk/star-wars-stars-reuniting-sequel-lucas-lets-slip-172815308.html
I am tasked with modeling a binary star system using VPython. The language itself is relatively irrelevant, as I can deal with the syntax. My problem is with the logic of it and how I should go about structuring the necessary calculations.
Homework Statement
A binary star system consists of...
When a star comes to the end of one phase in its life (eg red giant -> white dwarf), or simply 'explodes', it results in the emission of a huge amount of matter (and energy, of course).
But what form does that matter take ??
If the star has been cool enough (or when the emitted matter...
Hello,
Does a star collapse directly to form a black hole without creating a supernova or whether a supernova forms some neutron stars which after crossing the TOV limit forms a black hole?
Thanks.
I was looking over my old physics course problems, and I can't figure out how I'm doing this one wrong.
Homework Statement
Two identical stars, each having mass and radius M=2*10^29 kg and R = 7 *10^8 m are initially at rest in outer space. Their initial separation (between centers) is the...
Hello,
I want to understand: just as the Crab Nebula is the result of SN 1054 and has a neutron star spinning at the center:
(a) Does all supernova produces a nebula?
(b) Does all supernova remnant has a neutron star at the center?
(c) What is the outcome of Kepler supernova i.e. SN...
Homework Statement
(a) Consider a binary star system in which the two stars have masses M1 and M2 and the stars move on circular orbits separated by a distance R. Derive the formula for the period of revolution.
(b) Suppose M1= 1.22M and M2= 0.64M (where M = mass of the sun) and R= 0.63...
Pulsars -- Rotating neutron star produces EM radiation?
Hello,
If a neutron star is composed of neutrons, which do not carry any electric charge then how it's rotation produces pulsars which are electromagnetic radiation?
Thanks.
On decays I have only a preliminary understanding. I was looking up the half life of a neutron for another reason.
The value I found for neutron decay for a free neutron was 10.3 seconds. Hope that's reasonably accurate.
Anyways knowing that neutrons are stable in a nucleus held together...
Measure phase and line voltages.
Measure currents in the three lines and neutral.
Measure total power dissipated in the load.
Calculate total apparent power absorbed by the load.
Determine power factor.
Draw phasor showing voltages and currents.P=P1 + P2
Q = √3(P2 - P1)
|S| = √(P2+Q2)
θ =...
It would be great if any of you could give me an aproximate formula of the star density of the milky way, as far as i know (and I'm not pretty sure), it falls off exponentially, both vertically and radially. The formula i have in my head would be something like
##Density \propto...
Hello everyone,
I have recently become interested in the physics behind the Star Wars saga and more particularly in the lightsaber. I have found an article on the web about, but not being very good in physics yet, there is a part which I find very hard to understand. I was just wondering if...
Homework Statement
If the exponent, α, in the mass-luminosity relationship is 3.0, estimate the lifetime
of the above star. (You can assume that the Sun’s lifetime is 1 x 10^10 years).
Homework Equations
L*/Lsun = (M*/Msun)^α
lifetime ∝ M/L ∝ M^-2
The Attempt at a Solution...
Homework Statement
A star as an apparent visual magnitude of 14 and an absolute visual magnitude of 14.7. I have worked out that its distance is 7 parsecs. The sun has an absolute visual magnitude of 4.8 and an effective temperature of 5800k. If the star has the same effective temperature of...
Hello,
The general description that we give for forming a star i.e. through supernova explosion or through some stellar disturbances...etc.etc.
How do we know? I mean to say is there any way for knowing, visualizing, or calculating the way how a star is formed, how it dies?
Is there any...
A star by the name of HE-1523-0901 is a star only about half a billion years younger than the universe. I understand that the universe expanded faster than light after the big-bang, but I am having a hard time understanding how one star from this time period may have wound up in the Milkyway...
I think I heard long ago that the redshift of all parts of the surface of a spinning star as seen from a distant point on the axis is expected to be the same, at least in theory, because of the following argument. Please can anyone confirm or refute this?
A body which is capable of being...
1. Statement
A star connected load of 3300 kVA at 18 kV and a power factor of 0,8 lagging is supplied by a three-phase transmission line having a resistance of 4Ω per phase and an inductive reactance of 7Ω per phase.
Determine:
a. the sending-end voltage
b. the percentage regulation
c...
This comes from this thread https://www.physicsforums.com/showthread.php?t=647627&page=7 discussion in posts #103,#104,#107 and #108.
The Oppenheimer-Snyder model was mentioned by PeterDonis as a more plausible model than the Schwarzschild spacetime, well this has an element of subjectivity...
My professor actually told us that it isn't, but I don't see how it's not. If he meant that one of the stars is not in equilibrium, then that would make sense to me.
I wrote a paper in the physics department's student newspaper at my school, which described why, in my opinion, I considered a neutron star's surface as the smoothest surface in the universe, I considered the space between the particles at the surface (thousands of times smaller than at TPN...
Hello, first time poster here!
I am trying to understand some results I am getting from this "Relativistic Star Ship Calculator". This site sets up the question I'm trying to answer exactly like I imagined it should (thanks to The Forever War). From the description:
The star ship...
Homework Statement
High resolution spectroscopy reveals that the H line is located at a wavelength
of 656.250 nm for this star. The wavelength of H measured in the lab is 656.280 nm.
Calculate the line-of-sight velocity of the star.
Homework Equations
Here's the Doppler...
Homework Statement
The two components of a double star are observed to move in circles of radii r1 and r2. What is the ratio of their masses? (Hint: Write down their accelerations in terms of the angular velocity of rotation, ω.)
Homework Equations
Newton's 2nd law? law of...
Homework Statement
In recent years, a number of nearby stars have been found to possesses planets. Suppose, the orbital radius of such a planet is found to be 4.9 1011 m, with a period of 1280 days. Find the mass of the star.
Homework Equations
T^2=4pi√((r^3)/Gm))
The Attempt at a...
A photon is (described by) an electromagnetic wave, meaning the oscillation of the E and the B field.
Now there is this single photon that comes from a faraway star and hits the CCD detector of some astronomical satellite. As an approximation consider that it traveled through vacuum for the...
I'm working on a problem where I have to find the little co-group and star of two wave vectors for a diamond structure (space group 227). I know I have to act on the vector by the symmetry operations in the group (perhaps only the ones in the isogonal point group, Oh?) and see if it remains the...
I was wondering today what is the colour of pure neutrons confined together, I'd guess it's either completely black or white, because it doesn't have the electric orbitals needed to generate different wavelengths. I'm generally guessing it just reflects light and is therefore what... maybe a...
Dear All,
I have encountered the following situation:
Given a node that is connected through n resistors to n ports.
One if the resistors is a negative resistance and equals to minus of all other resistors in parallel.
\frac{1}{R_n} =- \sum_{i=1}^{n-1} \frac{1}{R_i}
Using the well known...
Homework Statement
The problem is assume Andromeda and the Milky Way are going to collide. the relative speed of them moving is 10^6m/s. assume each star has the radius of our sun (6.955*10^8m) the distance between each star is 3.1*10^18 m. how long will it take for a star to collide with...
National Geographic is featuring this star trail picture this week on their wallpaper page (found here http://ngm.nationalgeographic.com/your-shot/weekly-wrapper/2012/img/0812wallpaper-week-4-1_1600.jpg). In the picture though I was wondering why the star trails appear so much more dense on the...
Homework Statement
In the context of image reconstruction using backprojection by CT scanners -
Why / how does backprojection cause star blur?
Homework Equations
Figure 13 of
http://depts.washington.edu/nucmed/IRL/pet_intro/intro_src/section4.html
and
Figure 25-16 of...
”True” proximity in plane and space (”Island and star best friends”)
”True” proximity in plane and space (”Island and star best friends”)
(To read this post in a more pleasant format, click here. My questions are in that document though, you will find them in this post.)
Recently I was on...
Homework Statement
A 415V, 50 Hz three phase supply supplies three balanced loads which draw a total
apparent power (S) of 38 kVA at a power factor of 0.78 lagging. The three loads are
as follows:
LOAD 1 (STAR): 10.6 kVA at a power factor of 0.57 lagging;
LOAD 2 (DELTA): 20 kW...
Any help on where I start with this question. Need to convert each force into its horizontal and vertical components, but don't know any angles apart from the 70N force acting straight down.
Hi all.
I have a question.
Is there a way to calculate the altitude and azimuth of a star at a given time using as an input the altitude and azimuth of that star at an earlier time, without having to convert those coordinates to RA and DEC?
The problem is that I want to calculate the position...