logo

Amazing video encyclopedia

Stars

Popular in this category (3,912)

 
NSFW

Science

Sun

The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers, i.e. 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System. About three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.

 
NSFW

Science

Supernova

A supernova is a transient astronomical event that occurs during the last stellar evolutionary stages of a star's life, either a massive star or a white dwarf, whose destruction is marked by one final, titanic explosion. This causes the sudden appearance of a "new" bright star, before slowly fading from sight over several weeks or months or years.

 
NSFW

Science

Neutron star

A neutron star is the collapsed core of a large star which before collapse had a total of between 10 and 29 solar masses. Neutron stars are the smallest and densest stars, not counting hypothetical quark stars and strange stars. Typically, neutron stars have a radius on the order of 10 kilometres (6.2 mi) and a mass between 1.4 and 2.16 solar masses. They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past the white dwarf star density to that of atomic nuclei. Once formed, they no longer actively generate heat, and cool over time; however, they may still evolve further through collision or accretion. Most of the basic models for these objects imply that neutron stars are composed almost entirely of neutrons ; the electrons and protons present in normal matter combine to produce neutrons at the conditions in a neutron star. Neutron stars are supported against further collapse by neutron degeneracy pressure, a phenomenon described by the Pauli exclusion principle, just as white dwarfs are supported against collapse by electron degeneracy pressure. If the remnant star has a mass greater than about 3 solar masses, it continues collapsing to form a black hole.

 
NSFW

Science

Polaris

Polaris, designated Alpha Ursae Minoris, commonly the North Star or Pole Star, is the brightest star in the constellation of Ursa Minor. It is very close to the north celestial pole, making it the current northern pole star. The revised Hipparcos parallax gives a distance to Polaris of about 433 light-years, while calculations by other methods derive distances around 30% closer.

 
NSFW

Science

White dwarf

A white dwarf, also called a degenerate dwarf, is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to that of the Sun, while its volume is comparable to that of Earth. A white dwarf's faint luminosity comes from the emission of stored thermal energy; no fusion takes place in a white dwarf wherein mass is converted to energy. The nearest known white dwarf is Sirius B, at 8.6 light years, the smaller component of the Sirius binary star. There are currently thought to be eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910. The name white dwarf was coined by Willem Luyten in 1922.

 
NSFW

Science

Star of Bethlehem

The Star of Bethlehem, or Christmas Star, appears only in the nativity story of the Gospel of Matthew, where "wise men from the East" (Magi) are inspired by the star to travel to Jerusalem. There they meet King Herod of Judea, and tell him they are heading to Bethlehem to pay homage to the newborn king of the Jews. Herod calls his scribes and priests who confirm to him that a verse from the Book of Micah interpreted as a prophecy, states that the Jewish Messiah would be born in Bethlehem to the south of Jerusalem. Secretly intending to find and kill the Messiah in order to preserve his own kingship, Herod invites the wise men to return to him on their way home.

 
NSFW

Science

Wolf–Rayet star

Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of highly ionised helium and nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. Their surface temperatures range from 30,000 K to around 200,000 K, hotter than almost all other stars.

 
NSFW

Science

Vega

Vega, also designated Alpha Lyrae, is the brightest star in the constellation of Lyra, the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus. It is relatively close at only 25 light-years from the Sun, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood.

 
NSFW

Science

Barnard's Star

Barnard's Star is a very-low-mass red dwarf about 6 light-years away from Earth in the constellation of Ophiuchus. It is the fourth-nearest-known individual star to the Sun and the closest star in the Northern Celestial Hemisphere. Despite its proximity, because of its dim apparent magnitude of +9.5, the star is invisible to the unaided eye; it is much brighter in the infrared than in visible light.

 
NSFW

Science

VY Canis Majoris

VY Canis Majoris is an extreme oxygen-rich red hypergiant (RHG) or red supergiant (RSG) and pulsating variable star located at 1.2 kiloparsecs (3,900 ly) away from Earth in the constellation of Canis Major. It is one of the largest known stars in the Milky Way, and is also one of the most luminous and massive red supergiants.

 
NSFW

Science

UY Scuti

UY Scuti is a red supergiant and pulsating variable star in the constellation Scutum. It is one of the largest known stars by radius and has a current mass of 10 M☉.

 
NSFW

Science

Red giant

A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around 5,000 K or lower. The appearance of the red giant is from yellow-orange to red, including the spectral types K and M, but also class S stars and most carbon stars.

 
NSFW

Science

Pole star

Pole star or polar star refers to a star, preferably bright, closely aligned to the axis of rotation of an astronomical object. This is most commonly used for stars close to the north and south celestial poles of the Earth. The name is frequently applied to Polaris in the constellation Ursa Minor, acknowledging its property of being the naked-eye star closest to the Earth's north celestial pole. The name Polaris, introduced in the 18th century, is shortened from New Latin stella polaris, meaning "pole star". Polaris is also known as Lodestar, Guiding Star, or North Star from its property of remaining in a fixed position throughout the course of the night and its use in celestial navigation. It is a dependable, though inexact, indicator of the direction toward the geographic north pole; it is virtually fixed, and its angle of elevation can also be used to determine latitude. The south celestial pole lacks a bright star like Polaris to mark its position. At present, the naked-eye star nearest to the celestial south pole is the faint Sigma Octantis, sometimes called the South Star.

 
NSFW

Science

Antares

Antares, also designated Alpha Scorpii, is on average the fifteenth-brightest star in the night sky, and the brightest star in the constellation of Scorpius. Distinctly reddish when viewed with the naked eye, Antares is a slow irregular variable star that ranges in brightness from apparent magnitude +0.6 to +1.6. Often referred to as "the heart of the scorpion", Antares is flanked by Sigma and Tau Scorpii in the centre of the constellation.

 
NSFW

Science

Arcturus

Arcturus, also designated Alpha Boötis, is the brightest star in the constellation of Boötes, the fourth-brightest in the night sky, and the brightest in the northern celestial hemisphere. Together with Spica and Denebola, Arcturus is part of the Spring Triangle asterism and, by extension, also of the Great Diamond along with the star Cor Caroli.