[AZ-Observing] Re: NGC 2024 - The Flame Nebula
- From: "Bernard Miller" <bgmiller011@xxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Tue, 5 Feb 2019 14:38:13 -0700
Brian,
Learn something new every day ð
Bernard
-----Original Message-----
From: az-observing-bounce@xxxxxxxxxxxxx <az-observing-bounce@xxxxxxxxxxxxx> On
Behalf Of Brian Skiff
Sent: Sunday, February 3, 2019 1:11 PM
To: az-observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] Re: NGC 2024 - The Flame Nebula
On Sun, 2019-02-03 at 12:16 -0700, Bernard Miller wrote:
Brian,
The star causing the ionization is actually Alnitak, which is the eastern
most star in Orion's belt.
Turns out we are both wrong! The idea that zeta Ori is the source of the
ionizing photons is due to Hubble in 1922, and is wrong for several reasons,
but consistent with what Hubble could have known about. The less-old lore
regards the star I mentioned as "it", but although that star turns out to be
hot enough, it is not luminous enough.
A quick trawl through the literature in SIMBAD indicates that the culprit
lies in the embedded star cluster --- completely obscured in the visible behind
the dark cloud of the nebula.
Specifically, the most luminous star there, called NGC 2024 IRS 2b, is doing
most of the work. It is obscured by something like 24 magnitudes at visible
wavelengths, so is not detectable by visual observers or visible-light imaging.
See the paper and nice images linked from:
<
http://simbad.u-strasbg.fr/simbad/sim-ref?bibcode 03A%26A...404..249B>
http://simbad.u-strasbg.fr/simbad/sim-ref?bibcode 03A%26A...404..249B
\Brian
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