APOD: The Pencil Nebula Supernova Shock Wave (2024 Feb 23)

[APOD Robot]

The Pencil Nebula Supernova Shock Wave

Explanation: This supernova shock wave plows through interstellar space at over 500,000 kilometers per hour. Centered and moving upward in the sharply detailed color composite its thin, bright, braided filaments are actually long ripples in a cosmic sheet of glowing gas seen almost edge-on. Discovered in the 1840s by Sir John Herschel, the narrow-looking nebula is sometimes known as Herschel's Ray. Cataloged as NGC 2736, its pointed appearance suggests its modern popular name, the Pencil Nebula. The Pencil Nebula is about 800 light-years away. Nearly 5 light-years long it represents only a small part of the Vela supernova remnant though. The enormous Vela remnant itself is around 100 light-years in diameter, the expanding debris cloud of a star that was seen to explode about 11,000 years ago. Initially, the section of the shock wave seen as the Pencil nebula was moving at millions of kilometers per hour but has slowed considerably, sweeping up surrounding interstellar material.

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[Ann]

Well, wow! Today's APOD is so large that all my three attachments will be used up in a jiffy!

Okay, here's the first one...

The Pencil Nebula Supernova Shock Wave.
Image Credit & Copyright: Helge Büsing

I like the caption:

This supernova shock wave plows through interstellar space at over 500,000 kilometers per hour. Centered and moving upward in the sharply detailed color composite its thin, bright, braided filaments are actually long ripples in a cosmic sheet of glowing gas seen almost edge-on.
...
Nearly 5 light-years long it represents only a small part of the Vela supernova remnant though.

Okay, so where in the Vela supernova remnant is the Pencil Nebula located?

Vela Supernova Remnant. Note the Pencil Nebula at far left. Credit & Copyright: Marco Lorenzi (Star Echoes)

---

Supernova remnants always contain at least some (blue-green) OIII emission. I'd say that Marco Lorenzi has used a lot of OIII to make the Vela supernova remnant look extra blue-green and set it apart from the red hydrogen alpha background.

Note the Pencil Nebula in Marco Lorenzi's image! It is at far left, at 9 o'clock.


Okay, but if we have a supernova remnant, then we may have some sort of compact body that was left behind after the explosion. And we do - it's the Vela pulsar! Time for my second attachment!

The Vela pulsar in the Vela supernova remnant. Note the
Pencil Nebula at lower left. Credit: Optical: DSS/Davide De Martin
X-ray: NASA/CXC/Univ of Toronto/M.Durant et al.

The Vela pulsar is one of the most important sources of X-rays in the Milky Way.

Milky Way in X-rays. Note the Vela pulsar (actually the Vela supernova remnant), the big yellowish blob at right. Credit: SRG/eROSITA

---

I found this video of the Vela Pulsar on Youtube:

Click to play embedded YouTube video.

And let's take a moment to consider the colors of the Pencil Nebula, and the optical colors of all of the Vela supernova remnant. The colors are blue-green and red.

Vela supernova remnant. Credit: Harel Boren. The outermost gaseous filaments are green from doubly ionized oxygen, OIII.

---

The blue-green gaseous filaments of the Vela supernova remnant are the outermost ones, the ones that crash into the interstellar medium and make it glow green from OIII. Behind the green OIII, the nebulosity is red from hydrogen alpha.

OIII represents a considerably higher degree of ionization than Hα. Green represents the impact itself, and red is the debris that follows after.

Ann

[johnnydeep]

The Pencil Nebula Supernova Shock Wave

Explanation: This supernova shock wave plows through interstellar space at over 500,000 kilometers per hour. Centered and moving upward in the sharply detailed color composite its thin, bright, braided filaments are actually long ripples in a cosmic sheet of glowing gas seen almost edge-on. Discovered in the 1840s by Sir John Herschel, the narrow-looking nebula is sometimes known as Herschel's Ray. Cataloged as NGC 2736, its pointed appearance suggests its modern popular name, the Pencil Nebula. The Pencil Nebula is about 800 light-years away. Nearly 5 light-years long it represents only a small part of the Vela supernova remnant though. The enormous Vela remnant itself is around 100 light-years in diameter, the expanding debris cloud of a star that was seen to explode about 11,000 years ago. Initially, the section of the shock wave seen as the Pencil nebula was moving at millions of kilometers per hour but has slowed considerably, sweeping up surrounding interstellar material.

That might be a first: the "sharply detailed color composite" link to the "source" is to a screen grab of the APOD page!

And I assume the Pencil Nebula is indeed located somewhere within the "enormous Vela remnant", but I grew tired of playing Where's Waldo. [ I'm pretty sure I found it before - or someone else pointed it out - in a long ago prior APOD. ]

EDIT: ok, Ann pointed out the Pencil in the larger image of the Vela nebula that she included, but I can't place either in the larger image of Vela from the Wikipedia link image -

Click to view full size image

:

[Ann]

The Pencil Nebula Supernova Shock Wave

Explanation: This supernova shock wave plows through interstellar space at over 500,000 kilometers per hour. Centered and moving upward in the sharply detailed color composite its thin, bright, braided filaments are actually long ripples in a cosmic sheet of glowing gas seen almost edge-on. Discovered in the 1840s by Sir John Herschel, the narrow-looking nebula is sometimes known as Herschel's Ray. Cataloged as NGC 2736, its pointed appearance suggests its modern popular name, the Pencil Nebula. The Pencil Nebula is about 800 light-years away. Nearly 5 light-years long it represents only a small part of the Vela supernova remnant though. The enormous Vela remnant itself is around 100 light-years in diameter, the expanding debris cloud of a star that was seen to explode about 11,000 years ago. Initially, the section of the shock wave seen as the Pencil nebula was moving at millions of kilometers per hour but has slowed considerably, sweeping up surrounding interstellar material.

That might be a first: the "sharply detailed color composite" link to the "source" is to a screen grab of the APOD page!

And I assume the Pencil Nebula is indeed located somewhere within the "enormous Vela remnant", but I grew tired of playing Where's Waldo. [ I'm pretty sure I found it before - or someone else pointed it out - in a long ago prior APOD. ]

EDIT: ok, Ann pointed out the Pencil in the larger image of the Vela nebula that she included, but I can't place either in the larger image of Vela from the Wikipedia link image -

Click to view full size image

:

Click to view full size image

That's because the Pencil Nebula is not in the Wikipedia image!

In this picture you can see both the Pencil Nebula and star HD 72067.
The Pencil Nebula and the star are far apart.

In Harel Borens image, you can see star HD 72067
but not the Pencil Nebula. It's off to the left.

In the Wikipedia image, HD 72067 figures prominently,
but the Pencil Nebula is way off to the left.

Ann

[Chris Peterson]

EDIT: ok, Ann pointed out the Pencil in the larger image of the Vela nebula that she included, but I can't place either in the larger image of Vela from the Wikipedia link image -

Thought it would be fun to try something I haven't done before, and just a little surprised how easy it was and how well it worked. Here are the two images aligned and scaled to each other, with the coordinates annotated.
_

[johnnydeep]

EDIT: ok, Ann pointed out the Pencil in the larger image of the Vela nebula that she included, but I can't place either in the larger image of Vela from the Wikipedia link image -

Thought it would be fun to try something I haven't done before, and just a little surprised how easy it was and how well it worked. Here are the two images aligned and scaled to each other, with the coordinates annotated.
_
vela_pencil.jpg

Thanks Chris (and Ann). Still had a hard time placing your aligned and scaled composite on top of the full larger image. This was the best I could do by eyeballing it. I'm sure you would have done better:

[johnnydeep]

Alright, here's my attempt at putting the two views of the Vela complex in the same frame - boy was that painful!:

[Chris Peterson]

Alright, here's my attempt at putting the two views of the Vela complex in the same frame - boy was that painful!:


the larger vela nebula complex - 2 views.jpg

Here's the output of my largely automated process, all three images.
_

[johnnydeep]

Alright, here's my attempt at putting the two views of the Vela complex in the same frame - boy was that painful!:


the larger vela nebula complex - 2 views.jpg

Here's the output of my largely automated process, all three images.
_
vela_lorenzi_c0_ra.jpg

Nice! Thanks. Happy to see that I was about right in my overlay. Also glad to hear that your process was "mostly automated". A PixInsight feature?

[Chris Peterson]

Alright, here's my attempt at putting the two views of the Vela complex in the same frame - boy was that painful!:


the larger vela nebula complex - 2 views.jpg

Here's the output of my largely automated process, all three images.
_
vela_lorenzi_c0_ra.jpg

Nice! Thanks. Glad to see it was "mostly automated". A PixInsight feature?

Yeah. I blind solved the images at astrometry.net, saved the solved FITS files it generates, open them in PixInsight and fully solve them there (which very accurately incorporates a distortion model), and then use a tool designed to align images for the purpose of creating a mosaic... which is sort of what this is, just incomplete. And PI also creates the rendering with grid, coordinates, objects, etc. I used Photoshop to stack the three aligned images and the annotation on their own layers and to overlay them for the final image. About 10 minutes of work- not bad at all.

[johnnydeep]

Here's the output of my largely automated process, all three images.
_
vela_lorenzi_c0_ra.jpg

Nice! Thanks. Glad to see it was "mostly automated". A PixInsight feature?

Yeah. I blind solved the images at astrometry.net, saved the solved FITS files it generates, open them in PixInsight and fully solve them there (which very accurately incorporates a distortion model), and then use a tool designed to align images for the purpose of creating a mosaic... which is sort of what this is, just incomplete. And PI also creates the rendering with grid, coordinates, objects, etc. I used Photoshop to stack the three aligned images and the annotation on their own layers and to overlay them for the final image. About 10 minutes of work- not bad at all.

For reference, it took me 20 minutes of futzing around in a PowerPoint work-alike app to get my semi-accurate results.

[DonB312]

Yeah. I blind solved the images at astrometry.net, saved the solved FITS files it generates, open them in PixInsight and fully solve them there (which very accurately incorporates a distortion model), and then use a tool designed to align images for the purpose of creating a mosaic... which is sort of what this is, just incomplete. And PI also creates the rendering with grid, coordinates, objects, etc. I used Photoshop to stack the three aligned images and the annotation on their own layers and to overlay them for the final image. About 10 minutes of work- not bad at all.

Very nice, Chris. I'm glad you thought of doing this and shared the results with us.