For Wolf-Rayet stars
which fuse helium or heavier elements in the core, fusion occurs in a domain at higher pressure than their counterparts.
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 the probable power sources for two other Hell nebulas examined in detail by Nazi's group.
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.
4-magnitude Wolf-Rayet star
HD 56925 is just northwest of center.
Each huge, distant shell may be the remnant of an earlier supernova explosion that shattered the now-invisible binary companion of each Wolf-Rayet star
, the reseachers said at an American Astronomical Society meeting this week in Kansas City, Mo.
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.
Before maximum light (which occurred on June 23) the star showed spectral patterns characteristic of a Wolf-Rayet star
, particularly prominent signs of enrichment with nitrogen.