ThanX Chris. With that I can basically agree.The Universe is ionized... and it is ionized by the radiation of every star, even little brown ones. It would be perfectly reasonable to say that the strongest source of ionizing radiation in the Cocoon is that one star, but all the same, if that star went away there's still plenty of energy to produce a significant (if much fainter) H II nebula.Well, basically I would still agree with Ann, because of the paper "The Cocoon Nebula and its ionizing star: do stellar and nebular abundances agree?" [size=65]https://www.researchgate.net/ ... ree[/size]
Most certainly, the nebula is being ionized by the output of many stars. If the BD+46 3474 system went away, we'd still observe a distinct H II region here.
The Cocoon nebula (IC 5146), a close-by Galactic H ii region ionized by a narrow line B0.5 V single star (BD+46 3474),...
The Cocoon nebula and its ionizing star, located at a distance of 800±80 pc, have a very similar chemical composition as
the Orion nebula and other B-type stars in the solar vicinity.
But the central region of the nebula actually contains about 30 relatively strong X-ray sources (cyan). These often correlate with O and B stars and are also visible in the IR. However, in contrast to the central stars of the Trifid Nebula, the fact that BD+46 3474 himself (green) is invisible even in X-ray is confusing me.
Statistics: Posted by AVAO — Mon Aug 19, 2024 6:56 pm — Replies 6 — Views 335