参宿七（Rigel A），在拜耳命名法中称为猎户座β（β Ori, β Orionis），是猎户座中最亮的恒星，并且是全天第7亮星，它的视星等为0.12等。从地球上观察，这是个三合星的系统，主星为参宿七A（Rigel A），是颗绝对星等 -7.84等的超巨星，亮度为太阳的130,000倍，是颗有固定周期的天鹅座α型变星。以小型望远镜就可以看见的参宿七B，本身就是光谱联星，由两颗光谱类型为B9的蓝白色恒星组成。

虽然在拜耳命名法为β星，但它始终比猎户座α（参宿四）明亮。从1943年以来，它的光谱就被当成其它恒星光谱分类的校准光谱之一。

Rigel, also known by its Bayer designation Beta Orionis (β Ori, β Orionis), is the brightest star in the constellation Orion and the seventh brightest star in the night sky, with visual magnitude 0.13. The star as seen from Earth is actually a triple or quadruple star system, with the primary star (Rigel A) a blue-white supergiant that is estimated to be anywhere from 120,000 to 279,000 times as luminous as the Sun, depending on method used to calculate its properties. It has exhausted its core hydrogen and swollen out to between 79 and 115 times the Sun's radius. It pulsates quasi-periodically and is classified as an Alpha Cygni variable. A companion, Rigel B, is 500 times fainter than the supergiant Rigel A and visible only with a telescope. Rigel B is itself a spectroscopic binary system, consisting of two main sequence blue-white stars of spectral type B9V that are estimated to be respectively 3.9 and 2.9 times as massive as the Sun. Rigel B also appears to have a very close visual companion Rigel C of almost identical appearance.