1) A small, metal object that is fired from a gun.
From M.Fr. boulette "cannonball, small ball," diminutive of boule "a ball," from L. bulla "round thing, bubble, knob," cognate with bowl and boil.
Golulé "bullet," variants gullé, goruk, gulu, gudé, guy "ball, sphere;" cf. Skt. guda- "ball, mouthful, lump, tumour;" Pali gula- "ball;" Gk. gloutos "rump;" L. glomus "ball," globus "globe;" Ger. Kugel, E. clot; PIE *gel- "to make into a ball."
Fr.: amas de la Balle, ~ du Boulet
A → cluster of galaxies at a → redshift of z = 0.296 undergoing a violent → merger process nearly in the → plane of the sky. Also known as 1E 0657-558. The head-on collision between the main cluster and a subcluster ramming with an apparent speed of about 4700 km s-1 occurred about 150 x 106 years ago. The two clusters are currently moving away from each other while the space between them is filled with a very hot gas (first observed in X-rays by → Chandra) resulting from the overheating due to the collision. The Bullet cluster has the highest X-ray luminosity and temperature of all known clusters. The X-ray gas of the bullet (amounting to 2 x 1013 solar masses) collides with the X-ray gas of the main cluster (1014 solar masses) and forms a well defined → supersonic (Mach 3) → bow shock. A significant offset between the distribution of X-ray emission and the mass distribution has been observed, and diversely interpreted.
The name Bullet refers to the smaller subcluster, that has created the bow shock; → cluster.