Wolf–Rayet

Wolf–Rayet (WR) can mean:

WR 104

Coordinates: 18^h 02^m 04.07^s, −23° 37′ 41.2″

WR 104 is a binary star system located about 7,500 light years from Earth, surrounded by a distinctive pinwheel nebula. The primary is a Wolf-Rayet star and the secondary is a main sequence OB star. Within the next few hundred thousand years, the system has a small probability of firing a gamma-ray burst in the general direction of the Earth.

Structure

WR 104 is surrounded by a distinctive dusty pinwheel nebula over 200 astronomical units long formed by interaction between the stellar winds of the two stars as they rotate and orbit. The spiral is composed of dust that would normally be prevented from forming by WR 104's intense radiation were it not for the star's companion. The region where the stellar wind from the two massive stars interacts compresses the material enough for the dust to form, and the rotation of the system causes the spiral-shaped pattern. The round appearance of the spiral leads to the conclusion that the system is seen almost pole on, and an almost circular orbital period of 220 days had been assumed from the pinwheel outflow pattern.

Rayet

Rayet is a commune in the Lot-et-Garonne department in south-western France.

See also

Rayet (crater)

Rayet is a small lunar impact crater that lies on the far side of the Moon, past the northeast limb. It lies to the southwest of the larger crater Millikan, and east of the comparably sized Petrie.

This crater is roughly circular in shape, with a sharp edge and relatively featureless inner walls that slope downward to the nearly level interior floor. The diameter of the floor is roughly two-thirds that of the crater. This formation has not been notably worn by impact erosion, and is otherwise undistinguished.

This feature is named after the French astronomer Georges Rayet (1839–1906).

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Rayet.

References