This is NASA/ESA Hubble Space Telescope The image shows a brilliant blue dwarf from a galaxy called Markarian 178 (Mark 178). The galaxy, which is significantly smaller than our Milky Way, lies 13 million light-years away in the constellation Ursa Major (Ursa Major).
Mrk 178 is one of more than 1,500 Marcarian galaxies. These galaxies get their name from Armenian astrophysicist Benjamin Markarian, who compiled a list of galaxies that are surprisingly bright in ultraviolet light.
While the bulk of the galaxy is blue due to an abundance of young, hot stars with little dust surrounding them, Mrk 178 takes on a red hue due to its collection of rare massive Wolf-Rayet stars. These stars are concentrated in the brightest reddish region near the edge of the galaxy. Wolf-Rayet stars eject their atmospheres with powerful winds, and the bright emission lines of their hot stellar winds are imprinted on the galaxy's spectrum. The lines from ionized hydrogen and oxygen are particularly strong and appear red in this photograph.
Massive stars enter the Wolf-Rayet phase of their evolution just before they collapse into black holes or neutron stars. Because Wolf-Rayet stars have only been around for a few million years, researchers know that something must have triggered Mrk 178's recent burst of star formation. At first glance, it's unclear what the cause might be—Mrk 178 appears to have no close galactic neighbors that could activate its gas to form new stars. Instead, researchers suspect that a gas cloud crashed into Mrk 178, or that the intergalactic medium disturbed its gas as the galaxy moved through space. Any disturbance could illuminate this tiny galaxy with a wave of bright new stars.
Media Contact:
Claire Andreoli ([email protected])
NASA Goddard Space Flight Center, Greenbelt, MD
