Best Binary Star

Sirius B is a dense white dwarf star orbiting within the Sirius system of Canis Major. It represents the remnant core of a once-massive star that exhausted its nuclear fuel. This object’s extreme density—a sun's mass packed into Earth-sized volume—makes it a valuable subject for astronomical researc...

Alpha Centauri B is a K-type main-sequence star located approximately 4.37 light-years from Earth in the Alpha Centauri star system. It orbits the larger and hotter G-type star Alpha Centauri A, forming a binary pair. Together with the red dwarf Proxima Centauri, these stars make up the closest stel...

Spica, designated Alpha Virginis, is the brightest star in the constellation of Virgo and a prominent binary star system. Located approximately 250 light-years from Earth, the system consists of two massive B-type stars orbiting so closely that their mutual gravity distorts them into ellipsoidal sha...

Procyon is a binary star system located in the constellation Canis Minor and is designated Alpha Canis Minoris. It is the eighth brightest star in the Earth's night sky and is situated approximately 11.5 light-years away. The primary component, Procyon A, is an F-type main-sequence star that is tran...

Albireo (Beta Cygni) is a double star system in the constellation Cygnus, appearing as the star marking the head of the swan asterism. The brighter primary component is a K-type giant star with a warm amber or golden hue, while the companion is a B-type main-sequence star appearing blue. The pair ca...

The Necklace Nebula (PN G054.2-03.4) is a planetary nebula located approximately 15,000 light-years from Earth in the northern constellation Sagitta. It was discovered in 2005 through the IPHAS H-alpha survey using the Isaac Newton Telescope. The nebula's distinctive ring of bright knots, resembling...

55 Cancri, also designated Rho1 Cancri or HD 75732, is a binary star system in the constellation Cancer located approximately 41 light-years from Earth. The primary star, 55 Cancri A, is a G8V main-sequence star comparable to but slightly smaller and cooler than the Sun, while the secondary, 55 Canc...

Procyon B is a white dwarf star and the fainter component of the Procyon binary system in the constellation Canis Minor. It orbits Procyon A, an F-type main-sequence star that is among the brightest stars in the night sky. The companion's existence was first inferred from irregularities in Procyon A...

Thuban, designated Alpha Draconis, is a star in the constellation Draco that served as Earth's north pole star during much of the third millennium BCE. The shift occurred because of axial precession, the slow 26,000-year wobble of Earth's rotational axis, which gradually changes the position of the...

Xi Ursae Majoris (also named Alula Australis) is a quadruple star system located approximately 27 to 29 light-years from Earth in the constellation Ursa Major. It holds the historical distinction of being the first binary star to have its orbit calculated, accomplished by French astronomer Félix Sav...

Alula Australis, designated Xi Ursae Majoris, is a multiple star system situated approximately 29 light-years from Earth in the northern constellation of Ursa Major. It historically holds significance as the first binary star system for which an orbital period was mathematically computed, achieved b...

Adhara is a binary star system located approximately 430 light-years away in the constellation Canis Major. The primary component is a blue-white giant or supergiant star that ranks as the second-brightest star in the constellation after Sirius. Historically significant for its ultraviolet emissions...

WR 140 is a variable star system located in the constellation Cygnus, consisting of a massive Wolf-Rayet star and a hot O-type giant companion. These two stars follow a highly eccentric 7.9-year orbit, coming close enough together to generate colliding stellar winds that shock the surrounding gas. T...

Izar, officially designated as Epsilon Boötis, is a well-known multiple star system located in the constellation Boötes. It consists of a bright orange giant primary star and a smaller, hot blue main-sequence companion, forming a celebrated telescopic double star. This pairing is highly valued by as...

NGC 2346, commonly called the Butterfly Planetary Nebula, is a bipolar planetary nebula located in the constellation Monoceros at an estimated distance of roughly 2,000 to 3,000 light-years. It was discovered by William Herschel in 1785. The nebula is distinguished by its central binary star system...

Alcor is a white main sequence star of spectral type A5V located approximately 81 light-years from Earth in the constellation Ursa Major. With an apparent visual magnitude near 4.0, it forms a close naked-eye visual pair with Mizar in the handle of the Big Dipper. The two stars were historically use...

Algieba, designated Gamma Leonis, is a prominent binary star system located in the zodiac constellation of Leo, approximately 126 light-years from Earth. The system consists of two evolved giant stars, a K-class orange giant and a G-class yellow giant, that orbit each other over a period of several...

WR 104 is a Wolf-Rayet star located roughly 7,800 light-years away in the constellation Sagittarius. It forms a spectroscopic binary with an OB companion, and the system is surrounded by a rotating pinwheel-shaped dust nebula imaged at infrared wavelengths. The orbital geometry has led researchers t...

Porrima, formally Gamma Virginis, is a binary star system in the constellation Virgo about 38 light-years from Earth. It consists of two similar main-sequence stars that orbit a common center of mass in a highly elliptical orbit lasting roughly 169 years. Their changing angular separation has made t...

Rasalhague, designated Alpha Ophiuchi, is the brightest star in the constellation Ophiuchus with an apparent magnitude of approximately 2.1. It is a binary star system located about 47 light-years from Earth, consisting of an A-type giant primary star and a smaller companion. The name Rasalhague der...

L 726-8, formally designated Luyten 726-8, is a binary star system situated approximately 8.7 light-years from Earth in the constellation Cetus. The system consists of two red dwarf stars, BL Ceti and UV Ceti, which orbit each other in a highly eccentric path. UV Ceti serves as the prototype for a c...

Avior, designated Epsilon Carinae, is a binary star system situated in the southern constellation of Carina. It consists of an aging orange giant star and a hotter blue-white main-sequence companion orbiting each other. Located approximately 630 light-years from Earth, the system is clearly visible...

Eta Cassiopeiae is a binary star system located approximately 19 light-years away in the constellation Cassiopeia. The primary component is a yellow-white G-type main-sequence star similar to the Sun, while its companion is an orange K-type dwarf. Orbiting each other with a period of roughly 480 yea...

Alhena, designated Gamma Geminorum, is a white giant star located approximately 109 light-years from Earth in the zodiacal constellation of Gemini. As the third-brightest star in the constellation, it is readily visible to the naked eye under dark sky conditions. Historically, its predictable heliac...

Zeta Reticuli is a wide binary system about 39 light-years away in the southern constellation Reticulum. Its two visible components, Zeta Reticuli 1 and Zeta Reticuli 2, are broadly Sun-like G-type main-sequence stars that share common motion through space and are separated widely enough to appear i...

Alphecca, formally Alpha Coronae Borealis, is the brightest star in Corona Borealis, the Northern Crown, and lies about 75 light-years from the Sun. It is an eclipsing spectroscopic binary whose two stars orbit closely enough that the system periodically changes brightness when one component passes...

Iota Ursae Majoris, formally named Talitha, is a quadruple star system located approximately 48 light-years from Earth in the northern constellation of Ursa Major. The primary component is an A-type main-sequence star with an apparent magnitude bright enough to be visible to the naked eye. Talitha f...

Groombridge 34 is a binary star system located 11.6 light-years away in the northern constellation of Andromeda. Both components are M-type red dwarf stars that orbit each other at a relatively wide separation, taking thousands of years to complete a single orbit. The system was first cataloged by t...

Delta Velorum, which holds the formal proper name Alsephina, is a prominent star system in the southern constellation of Vela. The primary component is an A-type white subgiant or giant star that forms the brightest point of the False Cross asterism. Alsephina is a binary system, featuring a primary...