Gamma Velorum

Gamma Velorum is a very bright star in the sky that belongs to the constellation Vela. It is actually made up of two stars that orbit each other, and each of these stars is itself a pair of stars that are so close together we need special tools to tell them apart. This makes Gamma Velorum a double star system with four stars in total!

The star is very easy to see at night because it shines very brightly. It has traditional names like Suhail al Muhlif and a modern nickname, Regor, but these names are not officially recognized by astronomers.

One of the stars in Gamma Velorum is a special kind of very hot and bright star called a Wolf–Rayet star. This makes Gamma Velorum important for scientists who study stars and how they change over time. The system also includes a very bright blue star and another blue star with a hidden companion.

Distance

Gamma Velorum is close enough to Earth that scientists can measure its distance very accurately. One way they measure this is by using a tool called Hipparcos, which gives a distance of 342 parsecs. Other methods, like studying how the star moves in its orbit, give similar numbers, around 336 parsecs. Yet another measurement using special tools called VLTI and interferometry suggests the distance might be a bit larger, about 368 parsecs, give or take 51 parsecs. All these numbers are a little smaller than the usual guess of 450 parsecs for a group of bright, young stars called the Vela OB2 association.

Stellar system

The Gamma Velorum system has at least four stars. The brightest one, γ² Velorum or γ Velorum A, is made of two stars that orbit each other. One is a large blue star, and the other is a special type of very hot star called a Wolf–Rayet star. These two stars orbit each other every 78.5 days. Both of these stars might one day explode as very bright stars called supernovae.

The dimmer star, γ¹ Velorum or γ Velorum B, also has two stars that orbit each other. This pair is close together and looks like one star without special equipment, but you can see them with binoculars. There are also several fainter stars nearby that move together with Gamma Velorum.

Etymology

The name of this star comes from Arabic, where it is called al Suhail al Muḥlīf, meaning "the oath-taker." The word Suhail is used for several bright stars and is also a popular Arabic name for boys.

In Chinese, the star is part of a group called Tiān Shè, meaning "Celestial Earth God's Temple," and it is known as Tiān Shè yī, or "the First Star of Celestial Earth God's Temple."

The name Regor was created as a fun idea by an astronaut, simply by spelling "Roger" backwards. Because of its special light patterns, this star is sometimes called the "Spectral Gem of Southern Skies."