Spiral arm
Videos
Spiral arms are a defining feature of spiral galaxies. They manifest as spiral-shaped regions of enhanced brightness within the galactic disc. Typically, spiral galaxies exhibit two or more spiral arm
The Whirlpool Galaxy (M51) has a pronounced spiral structure
NGC 1300 is a spiral galaxy with a pronounced bar
NGC 4314 (SBa)
M95 (SBb)
SSPSF model
Videos
The SSPSF model of star formation was proposed by Mueller & Arnett in 1976, generalized afterward by Gerola & Seiden in 1978 and Gerola, Seiden, & Schulman in 1980. This model proposes that star forma
Spiral arm
…the centre and the contribution of the bulge to the total luminosity. Two main theories have been proposed to explain the origin of spiral arms: the stochastic self-propagating star formation model and the density wave theory. These theories describe different variants of the spiral structure and do not exclude each other. In addition to these…
This image from NASA Spitzer Space Telescope shows the supernova remnant Henize 206, in which new stars heat the gas.
In 1995, the spiral galaxy NGC 4414 was imaged by the Hubble Space Telescope.