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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.”


Libra, the Scales

Libra, the Scales October 4, 2011

Radio Programs

Capella Measuring a double binary star system October 16, 2019

Beta Lyrae A big shift in a binary star system October 4, 2019

Double Black Holes Not seeing double stars September 27, 2019

Black Holes Galore Black holes in the Milky Way September 26, 2019

The Dolphin’s Snout The dolphin’s contrasting colors July 27, 2019

Cygnus X-1 A giant star vanishes from view July 11, 2019

Rasalhague The “dizzy” head of the serpent bearer June 30, 2019

Messier 10 Rejuvenation for some old stars June 19, 2019

Moon and Spica A pair of bright stellar “eggs” June 12, 2019

Moon and Antares One of the biggest of the big April 21, 2019

Moon and Regulus A stellar flip-flop March 18, 2019

Black Widows Dead stars with dying mates March 4, 2019

Alphard A mystery in the water snake February 23, 2019

The Twins A goodly supply of twins January 26, 2019

Navi A bright, busy star system January 21, 2019

Skull Nebula The glowing “skull” of a dying star January 5, 2019

Collision Zones A big impact around a young star October 15, 2018

Capricornus Following the sea-goat October 9, 2018

Fomalhaut System A star with distant relatives September 22, 2018

Symbiotes A busy “symbiotic” star September 19, 2018

61 Cygni Zeroing in on a nearby star August 4, 2018

Albireo The swan’s colorful beak July 28, 2018

Moon and Companions Siblings that have an impact July 19, 2018

16 Cygni Two Sun-like stars in a single system July 3, 2018

Building Big Black Holes Building bigger black holes June 26, 2018

Future Supernova A busy star with a violent future June 5, 2018

VW Cephei Two stars in a tight embrace May 19, 2018

Future Cannibal A future act of stellar cannibalism May 6, 2018

Moon and Spica Two stars with different fates April 27, 2018

Cor Caroli Dark blemishes on a big star April 22, 2018

Bright Quartet A fascinating stellar quartet April 11, 2018

Lunar Eclipse II A repeat performance for the Moon January 20, 2018

Balancing Planets Flanking the scorpion’s claw December 29, 2017

Stellar Kiss Two stars that may become one December 28, 2017

Capella Bright stars with a bright future November 25, 2017

Mirfak Looking for a companion October 30, 2017

Capricornus The weird and wonderful sea-goat October 13, 2017

Double Double Doubling up on stars in the harp September 30, 2017

V404 Cygni A binge-eating black hole September 1, 2017

Wild Duck Cluster Measuring the age of some wild ducks August 27, 2017

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

Featured Images

Simulation of two merging black holes

Double Darkness September 27, 2019

X-ray image of light echoes from V404 Cygni

Echoes of a Black Hole August 28, 2019

The star system Apep, which may detonate as a gamma-ray burst

Spooky Star August 15, 2019

Moon and Spica, evening of June 12, 2019

Double Giant June 12, 2019


The Herdsman May 9, 2019

Artist's concept of two neutron stars merging to make a black hole

Violent Merger September 14, 2018


Colorful Beak July 28, 2018

Orion Nebula and the star system Iota Orionis

Mismatched Twins March 23, 2018

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