what r stars made of?

Answer 1

A star is a massive, compact body of plasma in outer space that is held together by its own gravity and is sufficiently massive to sustain nuclear fusion in a very dense, hot core region. This fusion of atomic nuclei generates the energy that is continuously radiated from the outer layers of the star during much of its life span.[1]

Astronomers can determine many of the properties of a star by observing its spectrum, luminosity and motion through space. Individual stars differ in their total mass, chemical composition, and age. The total mass of a star is the principal determinant in its evolution and eventual fate. Other characteristics of a star include the diameter, rotation, movement and temperature. A plot of the star's temperature against luminosity, known as a Hertzsprung-Russell diagram (HR-diagram), allows the current age and evolutionary state of the star to be determined.

A star begins as a collapsing cloud of material that is primarily composed of hydrogen, with some helium and heavier trace elements. Once the stellar core is sufficiently dense, a portion of the hydrogen is converted into helium through the process of nuclear fusion. The remainder of the star's interior carries energy away from the core through a combination of radiation and convective processes. At the surface this energy generates a stellar wind and is radiated into space.

Once the hydrogen fuel at the core is exhausted, a star of at least 0.4 times the mass of the Sun[2] expands to becomes a red giant, fusing heavier elements at the core, or in shells around the core. It then evolves into a degenerate form, recycling a portion of the matter into the interstellar environment where it will form a new generation of stars with a higher proportion of heavy elements.[3]

Binary and multi-star systems consist of two or more stars that are gravitationally bound, and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution.[4]

The interior of a stable, main sequence star is in a state of equilibrium in which the forces in any small volume exactly counterbalance each other. The balancing forces consist of inward directed gravitational force and the opposing pressure from the thermal energy of the plasma gas. For these forces to balance out, the temperature at the core of a typical star to be on the order of 107 °C or higher. The resulting temperature and pressure at the hydrogen-burning core of a main sequence star are sufficient for nuclear fusion to occur, and for sufficient energy to be produced to prevent further collapse of the star.[75]

As atomic nuclei are fused in the core, they emit energy in the form of gamma rays. These photons interact with the surrounding plasma, adding to the thermal energy at the core. Stars on the main sequence convert hydrogen into helium, creating a slowly but steadily increasing proportion of helium in the core. Eventually the helium content becomes predominant and energy production ceases at the core. Instead fusion occurs in a slowly expanding shell around the degenerate helium core.[76]

In addition to hydrostatic equilibrium, the interior of a stable star will also maintain an energy balance of thermal equilibrium. There is a radial temperature gradient throughout the interior that results in a flux of energy flowing toward the exterior. The outgoing flux of energy leaving a shell within the star will exactly match the incoming flux.

The radiation zone is the region within the stellar interior where radiative transfer is sufficiently efficient to maintain the flux of energy. In this region the plasma will not be perturbed and any mass motions will die out. If this is not the case, however, then the plasma becomes unstable and convection will occur, forming a convection zone. This can occur, for example, in regions where very high energy fluxes occur, as near the core, or in areas with high opacity, as in the outer envelope.[75]

The occurrence of convection in the outer envelope of a main sequence star depends on the spectral type. Massive stars several times the mass of the Sun have a convection zone deep within the interior and a radiative zone in the outer layers. Smaller stars such as the Sun are just the opposite, with the convective zone located in the outer layers.[77] Red dwarf stars with less than 0.4 solar masses are convective throughout, which prevents the accumulation of a helium core.[2] For most stars the convective zones will also vary over time as the star ages and the constitution of the interior is modified.[75]

The portion of a main sequence star that is visible to an observer is called the photosphere. This is the layer at which the plasma gas of the star becomes transparent to photons of light. From here, the energy generated at the core becomes free to propagate out into space. It is within the photosphere that sun spots, or regions of lower than average temperature, appear.

Above the level of the photosphere is the stellar atmosphere. In a main sequence star such as the Sun, the lowest level of the atmosphere is the thin chromosphere region, where spicules appear and stellar flares begin. This is surrounded by a transition region, where the temperature rapidly increases within a distance of only 100 km. Beyond this is the corona, a volume of super-heated plasma that can extend outward to several million kilometres.[78] The existence of a corona appears to be dependent on a convective zone in the outer layers of the star.[77] Despite its high temperature, the corona emits very little light. The corona region of the Sun is normally only visible during a solar eclipse.

From the corona, a stellar wind of plasma particles expands outward from the star, propagating until it interacts with the interstellar medium.

Answer 2

A star is a massive, compact body of plasma in outer space that is held together by its own gravity and is sufficiently massive to sustain nuclear fusion in a very dense, hot core region. This fusion of atomic nuclei generates the energy that is continuously radiated from the outer layers of the star during much of its life span.[1]

Astronomers can determine many of the properties of a star by observing its spectrum, luminosity and motion through space. Individual stars differ in their total mass, chemical composition, and age. The total mass of a star is the principal determinant in its evolution and eventual fate. Other characteristics of a star include the diameter, rotation, movement and temperature. A plot of the star's temperature against luminosity, known as a Hertzsprung-Russell diagram (HR-diagram), allows the current age and evolutionary state of the star to be determined.

A star begins as a collapsing cloud of material that is primarily composed of hydrogen, with some helium and heavier trace elements. Once the stellar core is sufficiently dense, a portion of the hydrogen is converted into helium through the process of nuclear fusion. The remainder of the star's interior carries energy away from the core through a combination of radiation and convective processes. At the surface this energy generates a stellar wind and is radiated into space.

Once the hydrogen fuel at the core is exhausted, a star of at least 0.4 times the mass of the Sun[2] expands to becomes a red giant, fusing heavier elements at the core, or in shells around the core. It then evolves into a degenerate form, recycling a portion of the matter into the interstellar environment where it will form a new generation of stars with a higher proportion of heavy elements.[3]

Binary and multi-star systems consist of two or more stars that are gravitationally bound, and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution.[4]

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Answer 3

The outer part of the stars is almost mostly hydrogen and helium..

But the inner core, could be made up of heavier elements.. even iron.. Infact the iron content of a star is used as the standard measurement of the amount of heavier elements in the stars...

The older the star gets, the more amount of heavier elements it contains...

Once the hydrogen supply exhausts, heavy stars turn into red-giants, and eventually the helium starts to fuse at its core.. Later, when it turns into a red super giant, even oxygen and carbon begin to fuse...

The star may take a different path of evolution and turn into a neutron star.. in this, matter doesn't exist as individual elements, but all the nuclear mass is compressed into one big lump which is extremely dense..

So.. the chemical composition of the stars depends on the evolutionary phase in which it is, its size (mass), and many other factors...

A star like our sun, is almost wholly hydrogen and helium.. with a small trace of heavier elements at the core...

Answer 4

Main sequence burning stars are primarily made of Hydrogen and Helium.

Answer 5

Stars are made up of Hydrogen gas. when their life is progressing, they produce energy using Nuclear Fusion. This involves the hydrogen nuclei be bonded with another one creating a helium nucleus, therefore releasing energy and light.

Answer 6

It is an asteroids. What the component of asteroids?? Of cource the raw materials which u need to access from internet. What make this asteroids be rename as stars because it is so close with our earth and the reflex of light from sun make it shinning which group as star.

Answer 7

Stars r made up of many different compounds they have carbon,methane,helium,hydrogen almost all the nobel gases that we might find on earth,
As far as my knowledge knows............

Answer 8

hydrogen and the products of the nuclear reactions of hydrogen, such as helium and progressively heavier elements, depending on the age of the star.

All these elements are in a state of plasma.

Answer 9

Hydrogen and Helium

Answer 10

super charged gas called plasma. most of the stars are made up of H2 and He.