I'm surprised by today's caption.
APOD Robot wrote:
This image showcases dense knots of dark interstellar dust, bright stars that have formed in the past few million years, fields of glowing hydrogen gas ionized by these stars, and great loops of gas expelled by dying stars.
Bright stars that have formed in the past million years... it is quite hard to spot which stars in this picture are likely products of the NGC 3576 star factory and which are simply foreground (or, in some cases, background) objects.
And... great loops expelled by dying stars? Dying stars?
What is known about any dying stars in the NGC 3576 nebula?
Let's hear what APOD Robot said about ongoing star production in the NGC 3576 nebula:
APOD Robot wrote:
A detailed study of NGC 3576, also known as NGC 3582 and NGC 3584, uncovered at least 33 massive stars in the end stages of formation
So we have dying stars and
33 massive likely pre-main sequence stars, "unborn baby whopper stars", all in the same nebula. Having massive star death and massive star formation in the same nebula is quite unusual.
Look at massive clusters Westerlund 1 and Westerlund 2:
Westerlund 1. Credit: ESO/VPHAS+ Survey/N. Wright
NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI),
and the Westerlund 2 Science Team
Westerlund 1 and Westerlund 2 are two massive young clusters in the Milky Way, but they differ in age, stellar evolution and nebular surroundings.
wrote about Westerlund 1:
Westerlund 1 (also called Ara Cluster, designated Wd1) is a compact young super star cluster in the Milky Way galaxy, about 3.5–5 kpc away from Earth. It is one of the most massive young star clusters in the Milky Way,...
The cluster contains a large number of rare, evolved, high-mass stars
, including: 6 yellow hypergiants, 4 red supergiants including Westerlund 1-26, one of the largest known stars, 24 Wolf-Rayet stars, a luminous blue variable, many OB supergiants, and an unusual supergiant sgB[e] star which has been proposed to be the remnant of a recent stellar merger.
wrote about Westerlund 2:
The cluster contains at least a dozen early O stars, of which at least three are eclipsing binaries. All are hotter than 38,000K and more luminous than 230,000 L☉. There are around 20 further O class stars in the cluster, all main sequence objects implying a very young age for the cluster
Several Wolf–Rayet stars are found in the vicinity of Westerlund 2, although not in the central core...
Westerlund 2 also contains a large number of pre-main sequence stars with masses below 2.5 M☉. These stars constrain the age of the cluster to near 2 Myr.
"Evolved stars" means stars that have begun the process of dying. Note that the highly evolved cluster Westerlund 2, which contains many "dying stars", seems to lack a nebula in its vicinity, whereas the young cluster Westerlund 2, which contains many pre-main sequence stars, "baby stars and fetus stars", displays a very substantial nebula to its southeast.
I find it confusing to be told about "dying stars" in relation to the very substantial nebula of NGC 3576. I admit that we could be talking about outbursts from Wolf-Rayet stars in NGC 3576, which may conceivably have caused the loops of this distinctively shaped nebula.