visual binary star

Directory

References

Discover

number zero, 0 balloon

Is Zero an Even or an Odd Number?

The Castillo, a Toltec-style pyramid, rises 79 feet (24 meters) above the plaza at Chichen Itza in Yucatan state, Mexico. The pyramid was built after invaders conquered the ancient Maya city in the tenth century.

What’s Inside the Pyramid at Chichén Itzá?

Illustration by the CDC, reveals ultrastructural morphology exhibited by coronaviruses. Note the spikes on the outer surface of the virus, which impart the look of a corona surrounding the virion, when viewed electron microscopically. A novel coronavirus,

The Top COVID-19 Vaccine Myths Spreading Online

Mayer Amschel Rothschild (1744-1855), founder of the house of Rothschild; lithograph by Friedrich Lieder, c. 1830.

Where Do Antisemitic Conspiracy Theories About the Rothschild Family Come From?

Macro of sheet music

10 Classical Music Composers to Know

Gills of three old specimens of webcap fungus (Cortinarius) in Gloucestershire, South West England. toxic, fungi, poisonous mushroom

7 of the World’s Most Poisonous Mushrooms

earthquake. Heavily damaged school in the town of Yingxiu after a major earthquake struck China's Sichuan Province on May 12, 2008.

The 6 Deadliest Earthquakes Since 1950

visual binary star

astronomy

Learn about this topic in these articles:

major reference

In star: Stellar masses
…the mode of observation employed: visual binaries, spectroscopic binaries, and eclipsing binaries.
Read More

binary stars

In binary star
…telescope, it is called a visual binary. Stars whose components are too close to each other to be distinguished visually can sometimes be identified as binaries by spectroscopic observation; as the members of these spectroscopic binaries move alternately toward Earth and away from it, a Doppler effect of frequency change…
Read More

eclipsing variable star

Table of Contents

Introduction References & Edit History Quick Facts & Related Topics

Images

illustration depicting the light curve of Algol

Read Next

solar eclipse, sun, moon, astronomy, space

How Do You Tell the Difference Between Total, Annular, Solar, and Lunar Eclipses?

Arrangement of the phases of the moon in total eclipse with Blood Moon

9 Celestial Omens

Spiral Galaxy type Sa-Sb or Sa/Sb in the constellation Virgo. The majestic Sombrero Galaxy Messier 104 (M104) or NGC 4594. The team took six pictures of the galaxy, stitched them together to create the final composite image. Photo from May-June 2003

9 Britannica Articles That Explain the Meaning of Life

1 July 2002: The Solar and Heliospheric Observatory (SOHO) satellite reveals a massive solar eruption more than 30 times the Earth's diameter. The eruption formed when a loop of a magnetic field over the surface of the Sun trapped hot gas.

6 Questions About the Sun Answered

Galaxy clusters like Abell 2744 can act as a natural cosmic lens, magnifying light from more distant, background objects through gravity. NASA's James Webb Space Telescope may be able to detect light from the first stars in the universe if they are gravitationally lensed by such clusters. (astronomy, space exploration, galaxies)

How Fast Is the Universe Expanding?

Discover

earthquake. Heavily damaged school in the town of Yingxiu after a major earthquake struck China's Sichuan Province on May 12, 2008.

The 6 Deadliest Earthquakes Since 1950

Ethel Rosenberg arrested in August 1950. Photograph dated Aug. 8, 1950. American civilians executed for espionage. Spies, communists, Julius Rosenberg

Spies Like Us: 10 Famous Names in the Espionage Game

Fish. Lionfish. Lion-fish. Turkey fish. Fire-fish. Red lionfish. Pterois volitans. Venomous fin spines. Coral reefs. Underwater. Ocean. Red lionfish swims by seaweed.

10 of the World’s Most Dangerous Fish

Encyclopaedia Britannica First Edition: Volume 1, Plate XXXVIII, Figure 2, Ark, Ark of the Covenant, a small chest, coffer, contains Aaron's rod, manna pot, tables of covenant, Schechinah, Divine Presence, oracle, shittim-wood, acacia tree

Where Is the Ark of the Covenant?

World Data Locator Map: Australia

Is Australia an Island?

An old worn baseball and wood bat

Who Really Invented Baseball?

The Colosseum, Rome, Italy. Giant amphitheatre built in Rome under the Flavian emperors. (ancient architecture; architectural ruins)

New Seven Wonders of the World

eclipsing variable star

astronomy

Also known as: eclipsing binary star

Written and fact-checked by The Editors of Encyclopaedia Britannica

Article History

Key People:: Henry Norris Russell

Related Topics:: eclipse; binary star

See all related content

eclipsing variable star, pair of stars revolving about their common centre of mass in an orbit whose plane passes through or very near the Earth. An observer on the Earth thus sees one member of the binary pass periodically over the face of the other and diminish its light through an eclipse. The star Algol was the first suggested as an eclipsing binary, by John Goodricke, in 1782. Thousands are now known. By combining measurements of the brightness variations with spectroscopic information for both stars of the pair, astronomers can determine the mass and size of each star. See also variable star; binary star.

This article was most recently revised and updated by Erik Gregersen.