APOD: Star Forming Region S106 (2016 Feb 16)

[APOD Robot]

Star Forming Region S106

Explanation: Massive star IRS 4 is beginning to spread its wings. Born only about 100,000 years ago, material streaming out from this newborn star has formed the nebula dubbed Sharpless 2-106 Nebula (S106), featured here. A large disk of dust and gas orbiting Infrared Source 4 (IRS 4), visible in brown near the image center, gives the nebula an hourglass or butterfly shape. S106 gas near IRS 4 acts as an emission nebula as it emits light after being ionized, while dust far from IRS 4 reflects light from the central star and so acts as a reflection nebula. Detailed inspection of a recent infrared image of S106 reveal hundreds of low-mass brown dwarf stars lurking in the nebula's gas. S106 spans about 2 light-years and lies about 2000 light-years away toward the constellation of the Swan (Cygnus).

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[Ann]

This is a golden oldie, although newly processed by Brandon Pimenta. It is certainly a stunning nebula.

Is there any information as to how massive IRS 4 is?

Ann

[geckzilla]

Brandon went quite a bit overboard on the sharpening filters for this one. Lot of dark halos around stars. Looks odd to me.

[Boomer12k]

I would call it...The Angel Nebula...really nice image.

:---[===] *

[Glima49]

I should note in the original data there were these little black things I had to clean off. As for why these artifacts are in the WFC3/IR data, I don't know.

[MarkBour]

Beautiful image. The color came out very aesthetically pleasing.

I should note in the original data there were these little black things I had to clean off. As for why these artifacts are in the WFC3/IR data, I don't know.

Was that a joke about the brown dwarfs?

[Ron-Astro Pharmacist]

This is a golden oldie, although newly processed by Brandon Pimenta. It is certainly a stunning nebula.

Is there any information as to how massive IRS 4 is?

Ann

888 is such a nice number. Star Forming Region S106 is loosing so much mass it's probably difficult to calculate.

In http://arxiv.org/pdf/astro-ph/0406344v1.pdf
"In Fig. 5 the star with a mass estimate of 102 M⊙ is source
50, corresponding to the central exciting star S106 IRS 4. The
value of 102 M⊙ is very probably overestimated, due to the
fact that the method we have used to derive a mass value for
each star does not take into account the possible presence of
an IR excess, which in this case is known to be present (e.g.
Felli et al. 1984 and Fig. 4)."

Also stated "For S106 IRS 4 the estimates
in the literature indicate a mass greater than 15 M⊙ (Felli et al.
1984) and therefore the presence of an IR excess does not affect
the placement of S106 IRS 4 in the highest mass bin."
Reference

[rstevenson]

Finally, I've managed a little pareidolia. Not quite of the Jesus on toast variety, but it's a first step. (With apologies to Brandon Pimenta, who will, I hope, forgive my taking liberties with his fine work...)

Rob

[JohnD]

I should note in the original data there were these little black things I had to clean off. As for why these artifacts are in the WFC3/IR data, I don't know.

Dark matter?
Nhoj

[geckzilla]

I should note in the original data there were these little black things I had to clean off. As for why these artifacts are in the WFC3/IR data, I don't know.

They have names. The big round one is called the Death Star. Read all about it:
http://www.stsci.edu/hst/wfc3/documents ... ctor8.html

[Ann]

This is a golden oldie, although newly processed by Brandon Pimenta. It is certainly a stunning nebula.

Is there any information as to how massive IRS 4 is?

Ann

888 is such a nice number. Star Forming Region S106 is loosing so much mass it's probably difficult to calculate.

In http://arxiv.org/pdf/astro-ph/0406344v1.pdf
"In Fig. 5 the star with a mass estimate of 102 M⊙ is source
50, corresponding to the central exciting star S106 IRS 4. The
value of 102 M⊙ is very probably overestimated, due to the
fact that the method we have used to derive a mass value for
each star does not take into account the possible presence of
an IR excess, which in this case is known to be present (e.g.
Felli et al. 1984 and Fig. 4)."

Also stated "For S106 IRS 4 the estimates
in the literature indicate a mass greater than 15 M⊙ (Felli et al.
1984) and therefore the presence of an IR excess does not affect
the placement of S106 IRS 4 in the highest mass bin."
Reference

Thanks!

102 M⊙ is a very high mass indeed, and stars that massive are extremely rare in the Milky Way. So yes, such a high mass for S106 IRS 4 is very probably overestimated. Then again, 15 M⊙ represents, comparatively speaking, a rather modest mass for a very high-mass star. It is probably just enough to make an O-type main sequence star. For comparison, Jim Kaler wrote about O9-type main sequence star 10 Lacertae:

From a surface heated to a quite-amazing 32,000 Kelvin, it radiates a with a luminosity of 26,800 Suns (the majority of the light in the invisible ultraviolet), from which we derive a radius 4.7 times that of the Sun and a great mass of 16 times solar.

Your source says:

S106 IRS 4 is a massive stellar object of spectral type O7–
B0 and luminosity of [0.4–1] × 10⁵ L⊙ (Gehrz et al. 1982;
Felli et al. 1984).

A spectral class of "only" O7-B0 suggests that S106 IRS 4 might lie just at the dividing line between spectral classes O and B, in which case 15 M⊙ would be a reasonable mass estimate. Then again, maybe not. At a very young age, stars belong to a redder, cooler spectral class than when they reach full maturity:

Given their young age however
they could be Herbig Ae/Be stars, which have significant
X-ray activity, or even their precursors, since according to the-
oretical models a two million year old star of 2–3 M⊙ will have
spectral type K–G.

So S106 IRS 4 might be headed for an O3 spectral class, the hottest class, in the future.

I have to say that the whole S106 nebula looks as if it was powered by the bipolar outflow of just one, very massive star. To me, it looks as if the stellar engine powering the nebula has to be more massive than 15 M⊙! (As if I would know. Oh well.)

Again, thanks, Ron! Very interesting.

Ann