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(sub-jÿ -ănt) A giant star of smaller size and lower luminosity than normal giants of the same spectral type, Alpha Crucis being an example. Subgiants form luminosity class IV, lying between the main-sequence stars and the giants on the Hertzsprung–Russell diagram.



a member of a group of cool stars located between the giants and the main sequence in the Hertzsprung-Russell diagram. By comparison to main sequence stars of the same luminosity, subgiants are larger and have lower surface temperatures. Most known examples of subgiants are found in eclipsing binary systems of the Algol type. Subgiants apparently represent a late stage in the development of binary stars.

References in periodicals archive ?
In their recently accepted paper entitled ( "A Hot Saturn Orbiting An Oscillating Late Subgiant Discovered by TESS," the scientists described TOI 197.01 as "hot Saturn" specifically because it is the same size as Saturn.
Spectral Classes Luminosity Classes Spectral Class Characteristics Luminosity Type Class O Hottest; blue I Supergiant B Blue-white II Bright giant A White III Giant F Yellow-White IV Subgiant G Yellow V Dwarf K Orange M Coolest; red Caption: CELESTIAL MILEPOSTS Most of the distances to the stars of the Winter ' Hexagon can be used as markers for moments in a human life.
The remarkable Gamma Cassiopeiae is a blue-white subgiant that is surrounded by a gaseous disc.
Its L will first become nearly twice larger (in addition to its already main-sequence doubled value of L today), making then [L.sub.[??]] [approximately equal to] [10.sup.34] erg/s--the result of a bloated object fluxing its energy through a larger surface area as our future Sun becomes an elderly subgiant star.
Washington, April 10 ( ANI ): Thanks to the sensitive far-infrared detection capabilities of the ESA's Herschel space observatory, astronomers have been able to obtain the first images of a dust belt - produced by colliding comets or asteroids - orbiting a subgiant star known to host a planetary system.
Delta 1 and 2 are both blue-white B-type subgiant stars with Delta 1, slightly brighter, at approximately 800 light years from Earth and Delta 2 at 1 100 light years distant.
In that sense, SBK's definition of the main sequence's end is about 6.5 billion years from now, after the Sun is left with a significantly hydrogen-depleted core and has begun to move fairly rapidly to lower temperatures, becoming a "subgiant" star.
Titled "KELT-11b: A Highly Inflated Sub-Saturn Exoplanet Transiting the V = 8 Subgiant HD 93396," (; the paper was published recently in the Astronomical Journal.
These stars are just past the main stage of their life hence, "retired", and are now puffing up into what's called a subgiant star.
These stars are just past the main stage of their life -- hence, "retired" -- and are now puffing up into what's called a subgiant star.
PREDAWN: If you're still looking low toward the east, you'll see Jupiter rising in Libra a couple of hours after midnight, followed shortly by the tight pair of Mars and the bluish white subgiant Beta (p) Scorpii (Graffias), in the head of the Scorpion.