A report on Star system

Star system named DI Cha. While only two stars are apparent, it is actually a quadruple system containing two sets of binary stars.
Orbits of the HR 6819 hierarchical triple star system: an inner binary with one star (orbit in blue) and a black hole (orbit in red), encircled by another star in a wider orbit (also in blue).
Subsystem notation in Tokovinin's Multiple Star Catalogue
Sirius A (center), with its white dwarf companion, Sirius B (lower left) taken by the Hubble Space Telescope.
HD 98800 is a quadruple star system located in the TW Hydrae association.

Small number of stars that orbit each other, bound by gravitational attraction.

- Star system
Star system named DI Cha. While only two stars are apparent, it is actually a quadruple system containing two sets of binary stars.

36 related topics with Alpha

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Binary system of two stars

Binary star

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System of two stars that are gravitationally bound to and in orbit around each other.

System of two stars that are gravitationally bound to and in orbit around each other.

Binary system of two stars
Edge-on disc of gas and dust present around the binary star system HD 106906
Algol B orbits Algol A. This animation was assembled from 55 images of the CHARA interferometer in the near-infrared H-band, sorted according to orbital phase.
Artist's conception of a cataclysmic variable system
Artist's impression of the binary star system AR Scorpii
Artist rendering of plasma ejections from V Hydrae
Artist's impression of the sight from a (hypothetical) moon of planet HD 188753 Ab (upper left), which orbits a triple star system. The brightest companion is just below the horizon.
Schematic of a binary star system with one planet on an S-type orbit and one on a P-type orbit
The two visibly distinguishable components of Albireo
Luhman 16, the third closest star system, contains two brown dwarfs.
Planet Lost in the Glare of Binary Stars (illustration)

It is estimated that approximately one third of the star systems in the Milky Way are binary or multiple, with the remaining two thirds being single stars.

People have interpreted patterns and images in the stars since ancient times. This 1690 depiction of the constellation of Leo, the lion, is by Johannes Hevelius.

Star

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Astronomical object comprising a luminous spheroid of plasma held together by its gravity.

Astronomical object comprising a luminous spheroid of plasma held together by its gravity.

People have interpreted patterns and images in the stars since ancient times. This 1690 depiction of the constellation of Leo, the lion, is by Johannes Hevelius.
Infrared image from NASA's Spitzer Space Telescope showing hundreds of thousands of stars in the Milky Way galaxy
Stellar evolution of low-mass (left cycle) and high-mass (right cycle) stars, with examples in italics
An example of a Hertzsprung–Russell diagram for a set of stars that includes the Sun (center) (see Classification)
Betelgeuse as seen by ALMA. This is the first time that ALMA has observed the surface of a star and resulted in the highest-resolution image of Betelgeuse available.
Onion-like layers at the core of a massive, evolved star just before core collapses
The Crab Nebula, remnants of a supernova that was first observed around 1050 AD
Artist's impression of the Sirius system, a white dwarf star in orbit around an A-type main-sequence star
This view of NGC 6397 includes stars known as blue stragglers for their location on the Hertzsprung–Russell diagram.
Some of the well-known stars with their apparent colors and relative sizes
The Pleiades, an open cluster of stars in the constellation of Taurus. These stars share a common motion through space.
Surface magnetic field of SU Aur (a young star of T Tauri type), reconstructed by means of Zeeman–Doppler imaging
The reflection nebula NGC 1999 is brilliantly illuminated by V380 Orionis. The black patch of sky is a vast hole of empty space and not a dark nebula as previously thought.
The asymmetrical appearance of Mira, an oscillating variable star
Internal structures of main sequence stars with masses indicated in solar masses, convection zones with arrowed cycles, and radiative zones with red flashes. Left to right, a red dwarf, a yellow dwarf, and a blue-white main sequence star
A cross-section of the Sun
Overview of consecutive fusion processes in massive stars

Stars can form orbital systems with other astronomical objects, as in the case of planetary systems and star systems with two or more stars.

Astronomers have mistakenly reported observations of a double star in place of J 900 and a faint star in the constellation of Gemini.

Double star

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Pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes.

Pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes.

Astronomers have mistakenly reported observations of a double star in place of J 900 and a faint star in the constellation of Gemini.
Artist's impression of the discs around the young stars HK Tauri A and B.

Multiple stars are also studied in this way, although the dynamics of multiple stellar systems are more complex than those of binary stars.

An artist's concept of a planetary system

Planetary system

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An artist's concept of a planetary system
Heliocentric model of the Solar System in Copernicus' manuscript
An artist's concept of a protoplanetary disk
Protoplanetary discs observed with the Very Large Telescope.
The Morgan-Keenan spectral classification
Debris disks detected in HST archival images of young stars, HD 141943 and HD 191089, using improved imaging processes (April 24, 2014).
The spacings between orbits vary widely amongst the different systems discovered by the Kepler spacecraft.
Location of habitable zone around different types of stars
90% of planets with known distances are within about 2000 light years of Earth, as of July 2014.

A planetary system is a set of gravitationally bound non-stellar objects in or out of orbit around a star or star system.

Alpha Centauri is the brightest object in the constellation of Centaurus (top left).

Alpha Centauri

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Gravitationally bound system of the closest stars and planets to the Solar System at 4.37 light-years from the Sun.

Gravitationally bound system of the closest stars and planets to the Solar System at 4.37 light-years from the Sun.

Alpha Centauri is the brightest object in the constellation of Centaurus (top left).
Apparent and true orbits of Alpha Centauri. The A component is held stationary, and the relative orbital motion of the B component is shown. The apparent orbit (thin ellipse) is the shape of the orbit as seen by an observer on Earth. The true orbit is the shape of the orbit viewed perpendicular to the plane of the orbital motion. According to the radial velocity versus time, the radial separation of A and B along the line of sight had reached a maximum in 2007, with B being further from Earth than A. The orbit is divided here into 80 points: each step refers to a timestep of approx. 0.99888 years or 364.84 days.
The relative sizes and colours of stars in the Alpha Centauri system, compared to the Sun
Relative positions of Sun, Alpha Centauri AB and Proxima Centauri. Grey dot is projection of Proxima Centauri, located at the same distance as Alpha Centauri AB.
The two bright stars at the lower right are Alpha (right) and Beta Centauri (left, above antenna). A line drawn through them points to the four bright stars of the Southern Cross, just to the right of the dome of the Danish 1.54 m telescope at La Silla Observatory in Chile.
Alpha Centauri AB taken in daylight by holding a Canon Powershot S100 in line with the eyepiece of a 110-mm refractor. The photo is one of the best frames of a video. The double star is clearly visible.
View of Alpha Centauri from the Digitized Sky Survey-2
Alpha Centauri A is of the same stellar type G2 as the Sun, while Alpha Centauri B is a K1-type star.
Closest stars to the Sun
Distances of the nearest stars from 20,000 years ago until 80,000 years in the future
Animation showing motion of Alpha Centauri through the sky. (The other stars are held fixed for didactic reasons) "Oggi" means today. "Anni" means years.
The discovery image of Alpha Centauri's candidate Neptunian planet, marked here as "C1".
Looking towards the sky around Orion from Alpha Centauri with Sirius near Betelgeuse, Procyon in Gemini, and the Sun in Cassiopeia generated by Celestia.
Simulated night-sky image with a "W" of stars from Cassiopeia connected by lines, and the Sun, labeled "Sol", as it would appear to the left of the "W"
The Very Large Telescope and Alpha Centauri

It is a triple star system consisting of α Centauri A (officially Rigil Kentaurus), α Centauri B (officially Toliman), and the closest star α Centauri C (officially Proxima Centauri).

Image of Sirius A and Sirius B taken by the Hubble Space Telescope. Sirius B, which is a white dwarf, can be seen as a faint point of light to the lower left of the much brighter Sirius A.

White dwarf

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Stellar core remnant composed mostly of electron-degenerate matter.

Stellar core remnant composed mostly of electron-degenerate matter.

Image of Sirius A and Sirius B taken by the Hubble Space Telescope. Sirius B, which is a white dwarf, can be seen as a faint point of light to the lower left of the much brighter Sirius A.
A comparison between the white dwarf IK Pegasi B (center), its A-class companion IK Pegasi A (left) and the Sun (right). This white dwarf has a surface temperature of 35,500 K.
The white dwarf cooling sequence seen by ESA's Gaia mission
Artist's impression of the WD J0914+1914 system.
Internal structures of white dwarfs. To the left is a newly formed white dwarf, in the center is a cooling and crystallizing white dwarf, and the right is a black dwarf.
Artist's impression of debris around a white dwarf
Comet falling into white dwarf (artist's impression)
The merger process of two co-orbiting white dwarfs produces gravitational waves
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The first white dwarf discovered was in the triple star system of 40 Eridani, which contains the relatively bright main sequence star 40 Eridani A, orbited at a distance by the closer binary system of the white dwarf 40 Eridani B and the main sequence red dwarf 40 Eridani C.

Alpha Centauri AB is the bright star to the left, which forms a triple star system with Proxima Centauri, circled in red. The bright star system to the right is Beta Centauri.

Proxima Centauri

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Small, low-mass star located 4.2465 ly away from the Sun in the southern constellation of Centaurus.

Small, low-mass star located 4.2465 ly away from the Sun in the southern constellation of Centaurus.

Alpha Centauri AB is the bright star to the left, which forms a triple star system with Proxima Centauri, circled in red. The bright star system to the right is Beta Centauri.
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Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° to the southwest of the Alpha Centauri AB pair.

A visual band light curve for YY Geminorum (Castor C), adapted from Butler et al. (2015)

Castor (star)

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Second-brightest object in the zodiac constellation of Gemini.

Second-brightest object in the zodiac constellation of Gemini.

A visual band light curve for YY Geminorum (Castor C), adapted from Butler et al. (2015)

Castor appears singular to the naked eye, but it is actually a sextuple star system organized into three binary pairs.

AAVSO light curve showing the 2009-11 eclipse of Epsilon Aurigae

Epsilon Aurigae

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AAVSO light curve showing the 2009-11 eclipse of Epsilon Aurigae
Bright class F star and companion Class B star surrounded by a dusty disk (artist impression)
The ε Aurigae system during an eclipse (artist impression)
A comparison chart for ε Aurigae: the numbered stars are comparison stars with the numbers giving the comparison star brightness in magnitudes (conventionally without the decimal point, which might be confused with a star)

Epsilon Aurigae (ε Aurigae, abbreviated Epsilon Aur, ε Aur) is a multiple star system in the northern constellation of Auriga, the charioteer.

Capella is the brightest star in the constellation of Auriga (upper left).

Capella

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Brightest star in the northern constellation of Auriga.

Brightest star in the northern constellation of Auriga.

Capella is the brightest star in the constellation of Auriga (upper left).
Building J (foreground) at Monte Albán
Annotated night sky image showing Auriga and the Pleiades—Capella is the brightest star, towards top left
Capella components compared with the Sun
Hertzsprung–Russell diagram showing an evolutionary track for a star of approximately the mass of the two Capella giants. The current states of Capella Aa and Ab are marked.

Although it appears to be a single star to the naked eye, Capella is actually a quadruple star system organized in two binary pairs, made up of the stars Capella Aa, Capella Ab, Capella H and Capella L. The primary pair, Capella Aa and Capella Ab, are two bright-yellow giant stars, both of which are around 2.5 times as massive as the Sun.