Star system named DI Cha. While only two stars are apparent, it is actually a quadruple system containing two sets of binary stars.
Alpha Centauri is the brightest object in the constellation of Centaurus (top left).
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).
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.
Subsystem notation in Tokovinin's Multiple Star Catalogue
The relative sizes and colours of stars in the Alpha Centauri system, compared to the Sun
Sirius A (center), with its white dwarf companion, Sirius B (lower left) taken by the Hubble Space Telescope.
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.
HD 98800 is a quadruple star system located in the TW Hydrae association.
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).

- Alpha Centauri

Alpha Centauri is a triple star composed of a main binary yellow dwarf pair (Alpha Centauri A and Alpha Centauri B), and an outlying red dwarf, Proxima Centauri. Together, A and B form a physical binary star, designated as Alpha Centauri AB, α Cen AB, or RHD 1 AB, where the AB denotes this is a binary system. The moderately eccentric orbit of the binary can make the components be as close as 11 AU or as far away as 36 AU. Proxima Centauri, also (though less frequently) called Alpha Centauri C, is much farther away (between 4300 and 13,000 AU) from α Cen AB, and orbits the central pair with a period of 547,000 (+66,000/-40,000) years.

- 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.

3 related topics

Alpha

Binary system of two stars

Binary star

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)

Orbital periods can be less than an hour (for AM CVn stars), or a few days (components of Beta Lyrae), but also hundreds of thousands of years (Proxima Centauri around Alpha Centauri AB).

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.

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

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.

Alpha Centauri

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

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.