Herschel's Ring in NB: 21hrs

[Placidus]

Herschel's Ring looks like it might be a supernova remnant, with its loculated, bubbles-within-bubbles wall structure, especially visible toward 2 o'clock.

But it isn't, not yet. It's a nebula created by a pre-supernova Wolf Rayet star whose strong stellar wind has slammed into and shock-jocked the pre-existing medium.

Big one (2MB) here (www.mikeberthonjones.smugmug.com/Category/Wolf-Rayet/i-mTVpZF6/0/O/Hershel%27s%20Ring%20Ha%205%20OIII% 206%20SII%2010hrs.jpg)

How do we know without a spectrograph? Two strong hints. The first is the extreme paucity of SII (here mapped to red), compared with acutal supernova remnants such as the Pencil Nebula or the area around Pismis 4 that we posted recently. The second is (perhaps) the very large amount of pre-existing medium hanging around, waiting to be scooped up, as seen as purish hydrogen alpha [green] toward the bottom left edge.

The complex bubble structures toward 2 o'clock are worth a close look. There are also some nice, fainter shocks glowing in OIII toward the left.

Q: Why is the image so green when we know that is sinful?

A: We are being true to the light, and true to the astrophysics. As explained before, this region is not a post-supernova spectacular. It is a relatively peaceful (greenpeace?), youthful (greenhorn?) dainty (Daintree rainforest?) area, with very little SII. Trying to make it battle red [SII] when it isn't would be unfaithful to the light, and unfaithful to the physics. Embrace the green, for what it is telling us.

Field 36 min arc, North up. Ha: 5hrs, OIII 6hrs; SII 10hrs, all in 1hr unbinned subs mostly at -30C. Aspen 20" PlaneWave. MI-760 fork. Half moon. Processing using our very own GoodLook 64.

Best,
Mike and Trish

[strongmanmike]

Mike and Trish, your palette rationale is hard to quibble so you may be on to a pivotal change in the way pretty pictures are interpreted! more power to you! :-) Lovely work!!!

Mike

[topheart]

I love it!!
I really appreciate everything you have done with this.

Thanks,
Tim

[Atmos]

Great image and an excellent write up, I'll have to look at it on something other than my iPhone under hard sunlight though :P

[Placidus]

Thanks, Mike, I'm thrilled that you like it as is. We've had several goes over the years, and it's always come up looking blurry and wishy-washy. The 10 hours of SII helped a lot, but there really isn't much more of it.



Thank you, Tim! :)



Cheers, Colin. Hope you're not disappointed when you see it on the big screen.

[Paul Haese]

Nice scale MnT. The colour is very similar to the image a did a few years back now. Nice detail and tight stars.

[Geoff45]

Nice picture and lovely lucid description of what is happening. I fully agree that NB should illustrate something physical and not just be a free-for-all-slap-together-palettes-to-produce-a-pretty-picture approach.

As someone once chipped "Keep the bast*rds. honest"
Cheers

[gregbradley]

Great work Mike. Its definitely go hard or go home. 1 hour subs - gulp.

Greg.

[RickS]

Lovely work, M&T, both on the image and the description :lol:

I have about 16 hours on this target from two years ago and have never managed to come up with an image I like, even if I disrespect the light. Yours is way better than anything I've managed so far!

Cheers,
Rick.

[E_ri_k]

Intersting object, and nice writeup :) I like the colour palette, looks good:thumbs:

Erik

[Placidus]

Hi, Paul. Your image is now in my "Brilliant works by others" catalogue. It has an interesting beastie at the very top, which is out of frame on ours.



Thanks muchly, Geoff. Perhaps the 16803 chip is a 'Don' Chipp.



Cheers, Greg! The long subs really only matter when there's very faint stuff to shoot. We puzzle about when to resort to 2x2 binning. Unbinned [SII] always seems to work out clearer and sharper; binned is a lot less gritty, and is sometimes the only way to see anything at all. Dunno.



Thanks so much Rick. Kind and encouraging words.



Hi, Erik! Glad you like it too.

Very best,
Mike and Trish

[gvanhau]

Very nice image and interesting object (I don't remember having it seen before).

[gregbradley]

I couldn't find an RA or DEC for this object. Do you know its RA DEC? Does it have an NGC number?

Greg.

[marc4darkskies]

Delicate, pretty and interesting M&T. Colours are very pleasing and, astrophysical justifications notwithstanding (:)), I don't see a preponderance of green at all. Very nicely done indeed! :thumbsup::thumbsup:

[Placidus]

Thanks, Geert. You can see it too from Chile.



NGC 3199, in Carina. The photo is centred at 10:17:25, -57:54:37 J2K.



Thanks muchly Marcus! Greatly encouraged.

[Bassnut]

Excellent colour treatment M&T and overall a pleasing effort. At the risk (after a few) of causeing offence. Having tried this myself, you certainly could have gone deeper with Ha, unless you have and havent stretched much?.

[Placidus]

Cheers, Fred!

Here's a (very jpeg compressed) version where everything is stretched more, but no change to the overall colour balance. My goal is that the image as a whole should remain colour neutral. It's brought out more of the diffuse Ha in the background, but I feel it detracts from the very fine bubble structures at 2 o'clock. Dunno.

Best,
Mike

[Slawomir]

Very interesting object and very skilfully processed, nice work MnT :thumbsup:

1hr subs and no satellite trails? Rick managed to capture so many in just 10-minute subs! LOL

[multiweb]

Love the color palette. Very deep shot. Beautiful field. :thumbsup:

[Placidus]

Thanks again, Suavi. It came out much bettter than our 2013 version, which seemed very blurry and low-contrast by comparison (Different camera, different focusing regime, -12C rather than -30C, poor flats, no dithering, more primitive processing).



Just checked the raw subs. Not a single satellite trail in 21 hours. Billions of cosmic ray hits. (Often wonder why we use statistical data rejection to remove the most distant and most violent and primitive astronomical events we ever photograph, but the pix do look better without 'em.)



Thanks, Marc. :)

[Shiraz]

I don't often think of "Wolf-Rayet" and "peaceful" as having similar connotations:lol:, but I guess that depends on how close you are to one.

From this distance, that is a great image with lots of very interesting stuff going on - the colours bring out the underlying physics and thanks for the informative discussion :thumbsup:.

[Placidus]

Thanks, Ray.

Aye, peaceful compared with an actual supernova, but noisy compared with here at the farm, with cattle quietly grazing.

I've started a tiny little research project: for a whole bunch of objects (or at least 36' arc regions including an object), set the zero point for each channel very carefully to the "foothill" of the histogram, so no data is lost, and then measure the average [SII], H-alpha, and [OIII] percentages for the region, just to try to find what is normal, and how consistent the ratios might be.

(Actually, today is not so peaceful. The neighbours seem to have purchased a new aeroplane and they're practicing touch-and-go landings once every three minutes. Their wheels are getting tangled in our washing. Hope they run out of fuel shortly. Otherwise, it's out with the photon torpedoes and the phasers)