M82: Starburst Galaxy
with a Superwind
From NASA’s Astronomy Picture of the Day
Also known as the Cigar
Galaxy for its elongated visual appearance, M82 is a starburst galaxy with
a superwind. In
fact, through ensuing supernova explosions and powerful winds from massive
stars, the burst of star formation in M82 is driving a prodigious outflow of
material.
Evidence for the superwind from
the galaxy's central regions is clear in this sharp telescopic
snapshot.
The composite image
highlights emission from long outflow filaments of atomic hydrogen gas in
reddish hues.
Some of the gas in the
superwind, enriched in heavy elements forged in the massive stars,
will eventually escape into intergalactic space.
Including narrow band
image data in the deep exposure has revealed a faint feature dubbed the cap. Perched about
35,000 light-years above the galaxy at the upper left, the cap appears to be
galactic halo material ionized by the superwind shock or intense ultraviolet
radiation from the young, massive stars in the galaxy's core.
Triggered by a close
encounter with nearby large galaxy M81, the furious
burst of star formation in M82 should last about 100 million years or so. M82
is 12 million light-years distant, near the northern boundary of Ursa Major.
Image Credit & Copyright: Ken Crawford (Rancho Del Sol Obs.)