Explanation:
Blown by fast winds from a hot, massive star,
this cosmic bubble is huge.
Cataloged as
Sharpless 2-308
it lies some 5,000 light-years away toward the well-trained constellation
Canis Major and
covers slightly more of the sky than a Full Moon.
That
corresponds
to a diameter of 60 light-years at its estimated distance.
The massive star that created the bubble, a
Wolf-Rayet star,
is the bright one
near the center
of the nebula.
Wolf-Rayet stars
have over 20 times the mass of the Sun and are thought to be in a brief,
pre-supernova phase
of massive star evolution.
Fast winds from this
Wolf-Rayet star
create the bubble-shaped nebula as they
sweep up slower moving material from an earlier phase of evolution.
The windblown nebula has an age of about
70,000 years.
Relatively faint emission captured by narrowband filters
in the deep image
is dominated by the glow of ionized oxygen atoms
mapped to a blue hue.
Presenting a
mostly harmless
outline, SH2-308 is also known as The Dolphin-head Nebula.
Source: https://apod.nasa.gov/apod/ap240607.html
