Zeta¹ Scorpii (Zeta¹ Sco, ζ¹ Scorpii, ζ¹ Sco) is a B-type

hypergiant A hypergiant ( luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term ''hypergiant'' is defined as luminosity class 0 (zero) in the MK ...

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Scorpius Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation whose recognition pred ...

. It has an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light ca ...

which varies between 4.66 and 4.86. It is a member of the Scorpius OB1 association, and potentially of the

open star cluster An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

NGC 6231, also known as the "Northern jewel box" cluster. ζ¹ Scorpii is a luminous blue variable according to its luminosity and spectral appearance, yet is has not shown the characteristic types of variability, hence is classified as a dormant LBV. Around 36 times as massive as the Sun, it is one of the most luminous stars known in the Galaxy, with an estimated bolometric luminosity between 850,000 and 1.3 million times that of the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

and a radius 103 to 126 times that of the Sun. The

stellar wind A stellar wind is a flow of gas ejected from the stellar atmosphere, upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spheri ...

from this supergiant is expelling matter from the star at the rate of per year, or roughly the equivalent to the Sun's mass every 640,000 years. ζ¹ Scorpii forms a naked eye double with ζ² Scorpii, but the stars are merely coincidentally near in the line of sight from Earth. ζ² is a mere 135

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s distant and much less luminous in real terms. ζ¹ Scorpii can also be distinguished from ζ², due to the latter's orange hue especially in long-exposure photographs.

References

{{Stars of Scorpius Scorpius B-type hypergiants 082671 Scorpii, Zeta1 152236 Emission-line stars 6262 CD-42 11633