Starship Asterisk*

NGC 7380: The Wizard Nebula

Explanation: What powers are being wielded in the Wizard Nebula? Gravitation strong enough to form stars, and stellar winds and radiations powerful enough to create and dissolve towers of gas. Located only 8,000 light years away, the Wizard nebula, featured here, surrounds developing open star cluster NGC 7380. Visually, the interplay of stars, gas, and dust has created a shape that appears to some like a fictional medieval sorcerer. The active star forming region spans 100 about light years, making it appear larger than the angular extent of the Moon. The Wizard Nebula can be located with a small telescope toward the constellation of the King of Aethiopia (Cepheus). Although the nebula may last only a few million years, some of the stars being formed may outlive our Sun.

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The Wizard Nebula looks very fine in Ioan Popa's image. Great details are seen in the dust. Still, I think that Michelle Ashford's image is even more revealing.

Wikipedia wrote about the ionizing pair of stars, DH Cephei:

This is a double-lined spectroscopic binary system consisting of two near-identical, massive, O-type main sequence stars. Evolutionary tracks place the stars close to the zero age main sequence, with an age of less than two million years. This is a detached binary with a close orbit having a period of 2.11 days, and the orbit is assumed to have circularized. The orbital plane is estimated to be inclined by an angle of 47°±1° to the line of sight from the Earth, which yields mass estimates of 38 and 34 times the mass of the Sun. Although initially suspected to be an eclipsing binary and given a variable star designation, it doesn't appear to be eclipsing. Instead, the system displays ellipsoidal light variations that are caused by tidal distortions.

This system lies at the center of the young open cluster NGC 7380. It is the primary ionizing source for the surrounding H II region designated S142. The pair are a source of X-ray emission, which may be the result of colliding stellar winds. Their measured X-ray luminosity is 3.2×1031 erg s−1. The location and rare class of these stars make them an important object for astronomical studies.

Wow, you know! These two stars have masses of 38 and 34 times the mass of the Sun! They are less than two million years old, almost newborn! They orbit one another in 2.11 days! They emit X-rays because their winds smash into one another!


Imagine these two stars colliding for real and going out in a blaze of glory to rival the gamma ray bursts of the supernovas in the distant past!

There are at least two other really interesting aspects of NGC 7380. Doesn't the star blowing a bubble (at upper left in the APOD) look neat? I thought it was a Wolf-Rayet star, but according to Simbad Astronomical Database, it is a B-type star.

The other thing I find interesting about NGC 7380 is how most of the dust structures are bright-rimmed as if they were evaporating due to the onslaught of ultraviolet light from DH Cephei, but some of the dust structures are all dark. I guess that this says something important about the geography, shape and position of the dust in relation to the hot binary pair of stars, but I can't figure out how the dark dust is located in relation to DH Cephei.

Ann

I was impressed when the description said that NGC 7380 is located "only" 8,000 light years away! That got me wondering how farther away is the Horsehead Nebula? Wikipedia states that the Horsehead is some 1,500 light years away. So that means the Horsehead is virtually in our neighborhood, just a hop, skip and jump away. Methinks that when civilization develops warp speed starships, we should decide to visit the Horsehead Nebula first before we head out to the close by NGC 7380

I like this photo I really wish I saw a likeness to a wizzard; I just don't! I guess I guess
I just need more imagination! I really like this APOD though! Oh; here he is!
Looking through todays APOD; I found this cute squirrel! I couldn't
transfer him; so I copied the url!
https://i0.wp.com/krusefeed.com/wp-cont ... uirrel.jpg
Now isn't he cute?

De58te wrote: ↑Mon Nov 14, 2022 12:24 pm I was impressed when the description said that NGC 7380 is located "only" 8,000 light years away! That got me wondering how farther away is the Horsehead Nebula? Wikipedia states that the Horsehead is some 1,500 light years away. So that means the Horsehead is virtually in our neighborhood, just a hop, skip and jump away. Methinks that when civilization develops warp speed starships, we should decide to visit the Horsehead Nebula first before we head out to the close by NGC 7380

According to the Gaia parallax, the distance to NGC 7380 is more like 9,600 light-years.

As for the Horsehead Nebula, there is no visible star in it that has been measured by Gaia. Or, correction, my software is not willing to show me a star in the Horsehead Nebula that I can try to find a parallax for!


But as you can see in the picture of the Horsehead Nebula by Ken Crawford, blue reflection nebula NGC 2023 is located very close to the Horsehead Nebula in the sky, and to me, they look like they are a part of the same large dust structure/molecular cloud. We may indeed assume that they are physically related (or at least located at more or less the same distance from us).

NGC 2023 is illuminated by magnitude 7.8 B-type star HD 37903, and the parallax of this star has been measured by Gaia. Because of that, we know that the distance to HD 37903 and NGC 2023, and presumably also to the Horsehead Nebula, is ~1,300 light-years.

Or to put it differently: The Wizard Nebula, NGC 7380, is some 7.5 times farther away than the Horsehead Nebula.

Ann

Edit: Using Simbad Astronomical Database, I managed to locate a star at the top of the Horsehead. That star is IRAS 05383-0228, a young stellar object, and Gaia has indeed measured a parallax for it. This parallax puts IRAS 05383-0228, and therefore the Horsehead Nebula, at ~1,300 light-years from us. So its distance is broadly the same as the distance to NGC 2023.

orin stepanek wrote: ↑Mon Nov 14, 2022 2:16 pm I really wish I saw a likeness to a wizzard; I just don't! I guess I guess
I just need more imagination! I really like this APOD though!

This is what I see!

I think he could use a wand though...

It always amazes me how astronomical photos of the interstellar medium seem to call for glorious music to accompany them!

zeecatman wrote: ↑Mon Nov 14, 2022 11:19 pm

orin stepanek wrote: ↑Mon Nov 14, 2022 2:16 pm I really wish I saw a likeness to a wizzard; I just don't! I guess I guess
I just need more imagination! I really like this APOD though!

Wizard_Popa_1975.jpg

This is what I see!

I think he could use a wand though...

Wow! You have a heck of an imagination! I wish I did! Looks more like a banana to me or a crescent!