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Binary and Multi-Star Systems

A binary is a pair of stars that orbit each other. A multi-star system consists of three or more stars. The stars in a binary or a multi-star system all formed from a single cloud of gas and dust, so they are true “siblings.”

Resources

Libra, the Scales

Libra, the Scales October 4, 2011

Radio Programs

Delta Cygni Spreading out a stellar trio July 31, 2017

Sigma Scorpii Impressive stars near the scorpion’s heart July 30, 2017

Black Widows Celestial creepy-crawlies July 21, 2017

Scorpion’s Tail The scorpion’s fearsome tail July 13, 2017

Scorpion’s Head An arachnid with a case of the “bighead” July 12, 2017

Zapped! A dead star zaps a close companion July 5, 2017

Red Nova An exploding star turns red June 28, 2017

Orange Triplets Three orange stars for the price of one June 24, 2017

Big Changes A Sun-like star picks up the pace June 16, 2017

Moon and Spica Learning about a bright stellar duo June 4, 2017

Kornephoros The leading light of the club bearer May 31, 2017

More Northern Crown The “re-death” of two dead stars May 28, 2017

Northern Crown Crowning the northern sky May 27, 2017

Doomed Star A star faces a fate worse than death May 9, 2017

Moon and Spica Different fates for stellar siblings May 8, 2017

The Most Beautiful The “most beautiful” stars April 30, 2017

Moon and Regulus A star that’s older than it looks April 6, 2017

Cor Caroli Twins with different life expectancies March 25, 2017

Giant Cannibal A giant star becomes a cannibal March 16, 2017

Kicked Out Two stars get kicked out of the nest February 18, 2017

Dubhe Two suns in an alien sky February 12, 2017

Heartbeat Stars Watching stars change shape February 6, 2017

Misaligned Disks Looking into the future of young stars February 3, 2017

Lepus Chasing down a celestial rabbit January 28, 2017

More Fornax Drinking from the fountain of youth January 20, 2017

Moon and Regulus Learning about a familiar star January 14, 2017

Castor A miniature “star cluster” January 7, 2017

Moon and Spica Making stellar companions December 22, 2016

Moon and Regulus Four stars for the price of one December 17, 2016

Slow Eater A black hole that’s a slow eater December 15, 2016

Capella Altering the lives of two stars December 10, 2016

Moon and Regulus Lining up a pair of stellar lamps November 20, 2016

Moon and Betelgeuse The life and times of a supergiant November 16, 2016

Z Camelopardalis From a flashlight to a searchlight October 28, 2016

Almach A colorful double star October 21, 2016

Vela X-1 A giant X-ray machine in the sky September 19, 2016

Delta Scorpii Head to head with the scorpion August 8, 2016

Double Orange Stars that are big, bright, and orange July 26, 2016

Delphinus The beautiful celestial dolphin July 10, 2016

Moon and Spica Two stars play a cosmic duet June 14, 2016

The Llama The sparkling eyes of the llama May 25, 2016

Moon and Spica Giant tides on giant stars May 17, 2016

Gamma-Ray Bursts II A final gasp from dead stars April 19, 2016

Moon and Regulus Give and take among the stars — after this. April 16, 2016

Moon and Gemini Nipping at the heel of a twin April 12, 2016

Zeta Herculis Stellar siblings spread out April 4, 2016

Dipper Twins Tying together two star systems March 25, 2016

Moon and Spica Living under brilliant suns March 24, 2016

Making Stars Ways to make stellar companions March 14, 2016

Faint Neighbors Two close but faint neighbors February 7, 2016

Moon and Regulus A stellar “king” and his entourage January 25, 2016

Procyon The revenge of the scrawny January 23, 2016

R Sculptoris Stirring up a stellar bubble December 11, 2015

Sheratan The hidden nature of a binary star October 24, 2015

Homunculus Nebula A giant star blows giant bubbles October 20, 2015

Rare Gems Yellow gems from the water bearer October 2, 2015

Mirach Stars at opposite ends of the scale September 28, 2015

Dabih A dizzying system of stars September 22, 2015

More Andromeda Galaxy Getting ready to put on a show September 16, 2015

Waking Up A black hole wakes up hungry September 14, 2015

Alpha Centauri Planet Taking the measure of a planet September 11, 2015

Luminous Red Novae One star born from two September 2, 2015

Making a Magnetar Making a powerful magnet August 5, 2015

Delta Cephei A surprise from a well-known star August 2, 2015

Delta Cygni Spreading out a stellar trio July 30, 2015

Future Outbursts Setting up future outbursts July 23, 2015

Bread Crumbs Leaving a trail of breadcrumbs July 22, 2015

The Stinger The scorpion’s bright stinger July 18, 2015

Doomed Stars Two stars with a bright future June 16, 2015

Small but Bright Tiny stars put on brilliant displays June 15, 2015

Alpha Centauri Putting three stars on the scales May 24, 2015

Moon and Leo “Weighing” two giant stars May 23, 2015

Future Quadruplets A star cloud prepares to give birth April 15, 2015

Moon and Regulus The intertwined lives of two stars March 29, 2015

MY Camelopardalis A brilliant duet for the giraffe March 14, 2015

Moon and Spica Safety first around an amazing star March 7, 2015

Morning Moon A bright future for the scorpion February 11, 2015

Bright Merger The fireworks of a hostile takeover February 10, 2015

Beta Monocerotis A brilliant set of triplets February 9, 2015

Procyon One dog leads another across the sky January 23, 2015

Orion’s Head Heading for the top of the hunter January 17, 2015

Robert Aitken An astronomer who saw double December 30, 2014

Alhena The bright foot of a celestial twin December 27, 2014

Superflares A big outburst from a tiny star December 2, 2014

Rara Avis II Dancing with the firebird November 29, 2014

Epsilon Aurigae Playing Frisbee with a bright star November 22, 2014

Moon and Companions Feeble companions for a bright star November 13, 2014

Brighter A bright star gets even brighter November 3, 2014

More Capella Bright giants with a shared evolution October 25, 2014

Fomalhaut II Faint companions for a bright star October 1, 2014

Moon and Regulus Keeping an old star looking young September 19, 2014

Rasalhague The head of the serpent bearer September 6, 2014

Dabih Covering up a passel of stars September 4, 2014

Sigma Scorpii Impressive stars near the scorpion’s heart August 8, 2014

Moon and Companions The scorpion’s southern claw August 2, 2014

Different Explosions Exploding stars with a difference July 18, 2014

Zombie Stars The night of the living dead stars July 16, 2014

Alphecca Stellar siblings with different futures June 27, 2014

Close Quartet A nearby stellar quartet June 21, 2014

Eta Carinae II Aggravating a supergiant star June 16, 2014

Eta Carinae Building up to a big eruption June 15, 2014

Moon and Spica Two stars with big futures June 7, 2014

Moon and Regulus A stellar whirling dervish June 2, 2014

Companionship Looking for stellar companions May 28, 2014

Too Close Getting too close to a dark monster May 17, 2014

Rasalhague A preview of coming attractions May 16, 2014

Black Widow Pulsars Celestial creepy-crawlies April 9, 2014

Heart of Charles Stirring up the Heart of Charles March 21, 2014

Castor Rare sextuplets among the stars February 28, 2014

Monoceros A vision in blue in the unicorn February 24, 2014

Moon and Spica A star of the first magnitude February 17, 2014

Dubhe A bright orphan in the Big Dipper February 14, 2014

EX Hydrae Two small but busy stars December 18, 2013

Super Origins A refugee from the planet Krypton December 13, 2013

Sirius Rising The right season for the Dog Star December 5, 2013

Capella A pair of bright, “puffy” stars November 18, 2013

Andromeda A colorful stellar quartet November 5, 2013

Fomalhaut Surprises from a well-studied star October 13, 2013

Merging Stars Two stars that become one October 4, 2013

ER Vulpeculae Two stars locked in a tight embrace September 26, 2013

Equuleus Two stars whose fates are intertwined August 23, 2013

Sheliak A stellar tug-of-war July 31, 2013

Black Hole Beacon A black hole announces its presence July 24, 2013

Zubenelgenubi A complex claw for the scorpion July 13, 2013

Moon and Regulus The lion’s quadruple heart July 10, 2013

Albireo A colorful stellar duo July 5, 2013

Northern Crown Crowning the night sky May 28, 2013

Moon and Spica Neighbors that stir things up April 23, 2013

Moon and Regulus Putting the squeeze on a star March 22, 2013

Cracking Up A neutron star cracks up March 21, 2013

Four Suns A world with four suns in the sky March 7, 2013

Ringing Beat The beat of vibrating stars March 5, 2013

Moon and Antares Two stars with different fates March 2, 2013

Moon and Regulus A different kind of star system February 23, 2013

Procyon A pair of stellar light bulbs February 21, 2013

Castor Three sets of stellar twins January 14, 2013

Moon and Spica Giant tides on giant stars January 3, 2013

Capella Bright stars with a bright future December 5, 2012

Venus and Spica A star that’s more than meets the eye November 16, 2012

Triangulum Aging stars in the triangle November 2, 2012

Halloween Star II A stellar cannibal for Halloween October 30, 2012

Halloween Star A two-headed stellar demon October 29, 2012

Tiny Black Hole A record-setting black hole October 25, 2012

Faint Triplets A faint set of stellar triplets October 6, 2012

Gamma Cephei The top of the king’s starry house September 1, 2012

Contact Binaries III A star system with a lot of variety August 16, 2012

Contact Binaries II Stirring up the family dynamics August 15, 2012

Contact Binaries Stars that can’t let go August 14, 2012

Cygnus X-1 A giant star vanishes from view July 31, 2012

Colorful Beak The swan’s colorful beak July 30, 2012

Equuleus Drawing up a little horse July 28, 2012

Moon and Spica Two bright stars for the price of one July 24, 2012

Zippy Planets Getting a big kick from a black hole June 27, 2012

Capella A quick exit for a “heavy” star April 26, 2012

Supernova 1987A, III A picture-perfect stellar explosion February 22, 2012

Sirius B A close companion for a bright star January 30, 2012

Moon and Hyades Staring into the face of the bull January 4, 2012

Featured Images

Artist's concept of AR Scorpii

Pulsing Corpse July 5, 2017
False-color image of the Boomerang Nebula, which is being created by a dying star

Cold Death June 7, 2017
HST view of 47 Tucanae

Star Globe May 9, 2017
Artist's concept of 47 Tucanae X9, a likely black hole-white dwarf binary

Living Dangerously March 16, 2017
X-Ray image of VLA J2130+12

Slow Eater December 15, 2016
Hubble Space Telescope view of the Gliese 229 system

Faint Neighbors February 7, 2016
X-ray energy forms expanding rings around the black hole V404 Cygni

Big Gulp Aftermath September 15, 2015
The system V664 Cassiopeia is creating a planetary nebula

Bread Crumbs July 23, 2015
Artist's concept of Alpha Centauri A and B, plus a planet

Busy Neighbor May 25, 2015
Artist's concept of MY Camelopardalis, a contact binary star system

Close Twins March 15, 2015
Superflare on one of the stars of DG Canum Venaticorum

Tiny Star, Big Outburst December 3, 2014
Artist's concept of Epsilon Aurigae

Playing Frisbee November 23, 2014
Hubble Space Telescope view of Eta Carinae

Future Fireworks June 16, 2014
Black-widow pulsar

Doomed Mate April 10, 2014
Artist's concept of black hole binary star system in the galaxy M101

Brilliant Darkness January 16, 2014
Illustration depicts the contact binary system W Ursae Majoris

Two-for-One Offer August 15, 2012
The Necklace Nebula, the remains of a dying star in Sagittarius

Ring of Fire August 15, 2011
Delta Lyrae and the Summer Triangle

Seeing Double July 10, 2011