APOD: The Elephant's Trunk Nebula in Cepheus (2020 Aug 01)

[APOD Robot]

The Elephant's Trunk Nebula in Cepheus

Explanation: Like an illustration in a galactic Just So Story, the Elephant's Trunk Nebula winds through the emission nebula and young star cluster complex IC 1396, in the high and far off constellation of Cepheus. Also known as vdB 142, the cosmic elephant's trunk is over 20 light-years long. This detailed close-up view was recorded through narrow band filters that transmit the light from ionized hydrogen and oxygen atoms in the region. The resulting composite highlights the bright swept-back ridges that outline pockets of cool interstellar dust and gas. Such embedded, dark, tendril-shaped clouds contain the raw material for star formation and hide protostars within. Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a large region on the sky, spanning over 5 degrees. This dramatic scene spans a 1 degree wide field of view though, about the size of 2 Full Moons.

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[Ann]

This star never gets any credit!

Brilliant O-type star HD 206267 and the Elephant's Trunk Nebula. Copyright: Davide de Martin/Science Photo Library.

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Why is nebula IC 1396 aglow? What force has sculpted the shape of the Elephant's Trunk Nebula? Tyger, Tyger, burning bright, what immortal hand or eye could frame thy fearful symmetry? (With apologies to William Blake.)

Don't know about the Tyger, but IC 1396 has been ionized and the Elephant's Trunk Nebula has been sculpted by HD 206267!

Ann

[Boomer12k]

Great looking shot... amazing... but IF you look at the top trunk "differently"... you can see a female cosmic "fish-woman"... The elephant's "eye" ...is HER eye... a rather fishy eye...lower she has... Legs...

:---[===] *

[orin stepanek]

Kind of an oddity; but the Elephant's Trunk has it's
own beauty and easily recognizable!

[neufer]

Click to play embedded YouTube video.

[johnnydeep]

Great looking shot... amazing... but IF you look at the top trunk "differently"... you can see a female cosmic "fish-woman"... The elephant's "eye" ...is HER eye... a rather fishy eye...lower she has... Legs...

:---[===] *

Sorry, but I fail to see much of an elephant's trunk, let alone a "fish woman"!

[BDanielMayfield]

Ann's right that the real star(s) of such scenes don't get enough respect.

The wikipedia article on HD 206267 is more user friendly than the link she provided though:

HD 206267A is a hierarchical triple star system in the northern circumpolar constellation of Cepheus. Two of the members form a spectroscopic binary that orbit each other with a period of 3.7 days, while a third member lies further away—it is unclear whether this third member is gravitationally bound to the pair. The system is emitting a stellar wind that reaches an exceptional velocity of 3,225 km/s, among the highest measured for stars of this type.[5]

HD 206267A
Observation data
Epoch J2000 Equinox J2000
Constellation
Cepheus
Right ascension
21h 38m 57.61881s[1]
Declination
+57° 29′ 20.5399″[1]
Apparent magnitude (V)
5.70[2]
Characteristics
Spectral type
O6V((f)) + O9V[3]
U−B color index
−0.72[2]
B−V color index
+0.22[2]
Astrometry
Radial velocity (Rv)
-7.8[4] km/s
Proper motion (μ)
RA: -1.25[1] mas/yr
Dec.: −4.58[1] mas/yr
Parallax (π)
1.65 ± 0.63[1] mas
Distance
approx. 2,000 ly
(approx. 600 pc)
Other designations
BD+56 2617, FK5 813, HD 206267, HIP 106886, HR 8281.

This stellar system lies in the nebula IC 1396. All three components are massive stars, and the intense ultraviolet radiation they give off ionizes the gas of IC 1396, and causes compression denser globules of the nebula, leading to star formation. The stellar wind produced by the stars is strong enough to strip nearby stars of their protoplanetary disks.[6]

At least two of these three massive stars are class O, (O6 & O9) and they are so close to each other that they orbit each other in only 3.7 days! They are destined (I would guess) to become a contact binary when the O6 swells after it leaves the main sequence. There will be at the very least one Supernova here (if the two stars merge) but more likely two SN and then possibly a kilonova when two neutron stars eventually collide.

Bruce

[gwrede]

A question:

The background stars seem "out of focus". But since depth-of-field really isn't an issue in astrophotographs, that must be an indication of the general sharpness of the image. -- In spite of that, some parts of the trunk really seem much sharper, even if you magnify the picture.

What is the explanation for this?

[Chris Peterson]

A question:

The background stars seem "out of focus". But since depth-of-field really isn't an issue in astrophotographs, that must be an indication of the general sharpness of the image. -- In spite of that, some parts of the trunk really seem much sharper, even if you magnify the picture.

What is the explanation for this?

I'd say some masked sharpening has been applied to the nebula regions.