Upsilon Coronae Borealis, Latinized from υ Coronae Borealis, is a solitary star in the northern constellation of

Corona Borealis Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a se ...

. It is a white-hued star that is dimly visible to the naked eye with an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

of 5.78. The distance to this object is approximately based on parallax. This is an

A-type main-sequence star An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between ...

with a stellar classification of A3V; a star that is currently fusing its core

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

. However, Palmer et al. (1968) had it classed as type A2IV, and thus it may be near or past its main sequence lifetime. It is a suspected

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...

of unknown type that has been measured ranging in brightness from magnitude 5.78 down to 5.88. Upsilon Coronae Borealis has three times the mass of the Sun and about 1.5 times the Sun's radius. It is spinning with a

projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulg ...

of 112 km/s. The star is radiating 151 times the

luminosity of the Sun The solar luminosity (), is a unit of radiant flux ( power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nominal ...

from its photosphere at an effective temperature of 8,098 K.

References

{{DEFAULTSORT:Upsilon Coronae Borealis A-type main-sequence stars Corona Borealis Coronae Borealis, Upsilon Durchmusterung objects Coronae Borealis, 18 146738 079757 6074