Star

starsmassive starstellar radiusAstrachemistry of the starsintermediate mass starsmassmassiveradiusStellar observations
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.wikipedia
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Helium

Hesuperfluid heliumhelium II
For at least a portion of its 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. Very low mass stars, with masses below 0.5, are fully convective and distribute helium evenly throughout the whole star while on the main sequence. Therefore, they never undergo shell burning, never become red giants, which cease fusing and become helium white dwarfs and slowly cool after exhausting their hydrogen. However, as the lifetime of stars is longer than the age of the universe, no such star has yet reached the white dwarf stage.

Babylonian astronomy

Babylonian astronomersBabylonianastronomer
The oldest accurately dated star chart was the result of ancient Egyptian astronomy in 1534 BC. The earliest known star catalogues were compiled by the ancient Babylonian astronomers of Mesopotamia in the late 2nd millennium BC, during the Kassite Period (c. 1531–1155 BC).

Cecilia Payne-Gaposchkin

Cecilia Payne[14Payne-Gaposchkin Medal and Prize
Cecilia Payne-Gaposchkin first proposed that stars were made primarily of hydrogen and helium in her 1925 PhD thesis.

Metallicity

metalmetal-richmetal-poor
Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, its luminosity, and spectrum respectively.

Stellar evolution

evolvedevolvingevolution
The total mass of a star is the main factor that determines its evolution and eventual fate.

Age of the universe

13.8 billion years ago13.8 billion yearsage
Very low mass stars, with masses below 0.5, are fully convective and distribute helium evenly throughout the whole star while on the main sequence. Therefore, they never undergo shell burning, never become red giants, which cease fusing and become helium white dwarfs and slowly cool after exhausting their hydrogen. However, as the lifetime of stars is longer than the age of the universe, no such star has yet reached the white dwarf stage.

List of largest stars

largest known starslargest stars knownlargest stars
List of largest known stars

Cosmic dust

interstellar dustdustspace dust
It is a function of the star's luminosity, its distance from Earth, the extinction effect of interstellar dust and gas, and the altering of the star's light as it passes through Earth's atmosphere.

Radiation

radiologicalradioactiveradiative
For at least a portion of its 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.

Effective temperature

surface temperatureeffective (surface) temperaturetemperature
The temperature is normally given in terms of an effective temperature, which is the temperature of an idealized black body that radiates its energy at the same luminosity per surface area as the star.

Betelgeuse

α OriBetelg'''euseBetelgeuse mass loss
Stars range in size from neutron stars, which vary anywhere from 20 to 40 km in diameter, to supergiants like Betelgeuse in the Orion constellation, which has a diameter about 1,000 times that of our sun.

Astronomy in the medieval Islamic world

astronomerastronomyMuslim astronomers
Medieval Islamic astronomers gave Arabic names to many stars that are still used today and they invented numerous astronomical instruments that could compute the positions of the stars.

Protoplanetary disk

protoplanetary discprotoplanetary disksprotoplanetary discs
These pre-main-sequence stars are often surrounded by a protoplanetary disk and powered mainly by the conversion of gravitational energy.

Star system

multiple star systemmultiple systemstriple star
A multi-star system consists of two or more gravitationally bound stars that orbit each other.

2MASS J0523-1403

With a mass only 80 times that of Jupiter, 2MASS J0523-1403 is the smallest known star undergoing nuclear fusion in its core.

List of exoplanets discovered using the Kepler spacecraft

1,013 confirmed exoplanets in about 440 star systemsa total of 2,321 candidatesdiscovered exoplanets