Ou4 - Un calmar geant dans une chauve-souris volante
Image Credit & Copyright:
Yannick Akar
A very faint but very large squid-like nebula is visible in planet Earth's sky
-- but inside a still larger bat.
The Giant Squid Nebula cataloged as Ou4, and Sh2-129 also known as the
Flying Bat Nebula, are both caught in this cosmic scene
toward the royal
royal constellation
Cepheus.
Composed with 55 hours of narrowband image data,
the telescopic field of view is 3 degrees or 6 Full Moons across.
Discovered in 2011 by
French astro-imager Nicolas
Outters, the Squid Nebula's alluring
bipolar shape is distinguished here
by the telltale blue-green
emission from
doubly ionized
oxygen atoms.
Though apparently
completely surrounded by the reddish
hydrogen
emission region Sh2-129, the true distance and nature of the Squid Nebula have been difficult to determine.
Still, a more recent investigation suggests Ou4 really does lie
within Sh2-129
some 2,300 light-years away.
Consistent with that scenario, Ou4 would represent a spectacular
outflow driven by HR8119, a
triple
system of hot, massive stars seen near the center of the nebula.
The truly giant Squid Nebula
would physically be nearly 50
light-years across.