In that process, the more compact star winds up gaining mass, and the original massive star loses its hydrogen envelope, exposing its helium core to become a Wolf-Rayet star
provided a possible answer because they released a lot of aluminum-26 but no iron-60.
"Thick winds continually poured off the progenitors of such stars, flooding their surroundings and draining the outer layers of the Wolf-Rayet stars
," NASA said.
are near the end of their lives and expel most of their outer layers into their surroundings before exploding as supernovae, with their cores imploding to form black holes.
Most Wolf-Rayet stars
either aren't hot enough or don't have enough gas surrounding them to produce bright, easy to see Hell nebulas, notes Claus Leitherer of the Space Telescope Science Institute in Baltimore.
"In just 100,000 years, this fast, dense wind removes as much mass from the Wolf-Rayet star
as our Sun contains," said Robin Corbet at the University of Maryland, Baltimore County.
It is losing mass rapidly through powerful stellar winds that have expelled the majority of its outermost hydrogen-rich layers, while its more mundane binary companion is probably about half as massive as the Wolf-Rayet star
, and orbits around it once every 208 days.
Drissen's team speculated that the winds blown either by bright, hot stars known as Wolf-Rayet stars
or by old stars called red supergiants could have pumped up the gas.
Three 11th-magnitude stars lie along the north portion of the rim, and the 11.4-magnitude Wolf-Rayet star
HD 56925 is just northwest of center.
Its companion also soon becomes a Wolf-Rayet star
and then undergoes a supernova explosion.
In 1996 a Belgian team led by Gregor Rauw studied the very massive Wolf-Rayet star
WR22 and measured a minimum mass of 72 Suns.
Large instruments reveal the object's bubble-like structure, which is due to fast stellar winds of a Wolf-Rayet star
colliding with the surrounding interstellar medium of gas and dust pervading the region.