Narrowband Centaurus A: First image of full Ha and OIII jet
Hi Everyone,
I am pleased to share this deep image of Centaurus A which I believe is the first image to reveal the full extent of its jet in both Ha and OIII emission. The image also shows the galaxies multiple faint outer shells and stellar streams that extend up to 40 arc minutes from the nucleus.
Cen A Jet
Cen A is well known for having a narrow relativistic jet emanating from its central supermassive black hole. This outflow results in an ionised hydrogen jet to the north of the galaxy. The AGN does have a weaker counter-jet which flows to the south of the galaxy, and some faint Ha emission has also been detected in this direction.
The northern Ha jet is characterised by brighter inner and outer filaments and the more recently recognised c filament. On my image you can also see faint Ha emission extending between the inner and outer filaments, and some diffuse Ha emission extending from the centre of Cen A towards the inner filament (labelled with arrows in figure below). This additional Ha emission appears to join the galaxy nucleus, and the inner and outer filaments into one continuous jet. A similar continuous jet is present on NUV images from the GALEX satellite (Neff et al, APJ 2015), however I have not seen a Ha continuous jet previously reported. The central Ha emission remains faintly visible on the RGBHO image through the stellar halo of the galaxy.
To the east of the nucleus there is a faint Ha cloud (circled red in figure above) located at the same location as a satellite dwarf galaxy candidate that was detected on deep images taken with the 6.5m Magellan telescope (Crnojevic et al, APJ 2016). This previously unreported Ha emission is likely to be the result of active star formation occurring within this dwarf galaxy.
My image also reveals Ha emission to the south which is likely caused by the counter jet in this direction, and this is only one of a few images to detect this southern jet feature.
OIII Jet
In addition to Ha emission, the jet also results in a smaller amount of OIII emission (see Morganti et al, MRAS 2011). Prior OIII images have only focused on the inner filament and the first part of the outer filament. This image is the first to show the full extent of the OIII emission jet, including two faint ionised OIII clouds located in the outer segment (circled in figure below). There is diffuse OIII emission radiating from the nucleus which is likely related to starburst within the disc, and this creates a subtle violet halo on the RGBHO image.
Background Ha clouds
On the wider view some extremely faint Ha clouds are visible scattered throughout the galactic cirrus. As the Ha has been processed using continuum subtraction these clouds represent true Ha emission rather than contamination from extended red emission, and in many areas are in different locations and morphology than the cirrus. These clouds likely represent Ha emission from the Milky Way that lie in our line of sight to Cen A.
Technical
Nikkor AF-S 400mm f/2.8E FL ED VR
ZWO ASI6200MM Pro
10Micron GM1000 HPS
Chroma Filters
Dunedin NZ
Integration 103h 45′ (B 6h 10′, G 5h 5′, Ha 65h 40′, OIII 15h 50′, R 11h)
Some excellent results there Mat, seems like these days, an image of Cen A that doesn't show the Ha jet is not a complete image anymore . As you know, I have a deep connection with this galaxy myself, so I love seeing new versions, as amateur imaging technology, processing techniques (and patience!), progresses. Like the recent features showcased around the heavily imaged M31, Cen A also seems to keep on delivering more subtleties to those that put the time in to look... even after all these years, it's great ....I wonder what will be possible in the coming years...
Nice work mate, love the faint subtle patches of Ha revealed in the outer Milky Way IFN environs and interesting how you suppressed the star field too, without doing so there a lot of stars around it!
Another great project, you and Rolf are a formidable team of Kiwis
Mike
Last edited by strongmanmike; 13-05-2023 at 12:15 PM.
I think it was Logan Carpenter who took a similar image with the jets a few years ago, he is also in New Zealand. Yours is also a great image
Thanks Nic! You are spot on, Logan did a really fantastic deep image which showed the inner/outer filaments, c jet and the southern jet. Another kiwi, Rolf Olsen set the benchmark a few years ago with an amazing 130 hour image , and was the first amateur to show the southern jet.
Some excellent results there Mat, seems like these days, an image of Cen A that doesn't show the Ha jet is not a complete image anymore . As you know, I have a deep connection with this galaxy myself, so I love seeing new versions, as amateur imaging technology, processing techniques (and patience!), progresses. Like the recent features showcased around the heavily imaged M31, Cen A also seems to keep on delivering more subtleties to those that put the time in to look... even after all these years, it's great ....I wonder what will be possible in the coming years...
Nice work mate, love the faint subtle patches of Ha revealed in the outer Milky Way IFN environs and interesting how you suppressed the star field too, without doing so there a lot of stars around it!
Another great project, you and Rolf are a formidable team of Kiwis
Mike
Many thanks Mike! Your deep images and your collaboration with Rolf + your MNRAS paper really set the benchmark for deep Cen A imaging and were a big inspiration . I'm glad you noticed the star field as I did try a few different versions, but decided to keep the stars more subdued to allow the more subtle narrowband emission features to be the star, as it were
Another outstanding artistic and scientific effort Matt. Great detail and much respect for the >100h integration - showing us that light particles/waves beats atmospheric dispersion, you just have to be patient and dedicated
Wow that’s a stunning piece of work Matt! The detail and depth in those jets is astounding and really well processed. I love how you’ve retained the background cirrus and Ha regions. And by the way, the detail through the core of the galaxy is extremely well resolved for 400mm fl too. Beautiful and intriguing project! Congratulations!!
You’ve put a tremendous amount of hard work into this project which has paid off in this spectacular galaxy image of Centaurus
Congratulations and thanks for sharing
Well done !!
Nice to see a wider view than normal with such amazing depth and detail. Truly spectacular.
Thanks Pete! A 400mm lens is not your typical galaxy scope so was nice to show it in a slightly different light.
Quote:
Originally Posted by Addos
Another outstanding artistic and scientific effort Matt. Great detail and much respect for the >100h integration - showing us that light particles/waves beats atmospheric dispersion, you just have to be patient and dedicated
Cheers Adam! It was very nice to get to 100hrs, I started this project last year when I was setting up each night, and finished it off this season with the observatory up and running which definitely helped
Wow that’s a stunning piece of work Matt! The detail and depth in those jets is astounding and really well processed. I love how you’ve retained the background cirrus and Ha regions. And by the way, the detail through the core of the galaxy is extremely well resolved for 400mm fl too. Beautiful and intriguing project! Congratulations!!
Many thanks Dave! I used drizzle integration for this (which was quite an undertaking with >100hrs integration ). I ended up a 2.94GB master RGB .xisf to work with but was very pleased with the amount of extra detail drizzle revealed.
You’ve put a tremendous amount of hard work into this project which has paid off in this spectacular galaxy image of Centaurus
Congratulations and thanks for sharing
Well done !!
That's a wonderful image Mat
I'd love to know if it was shot wide open with the Nikkor or at what stop, if you could advise?
Best
JA
Thanks JA! I use a 3D printed aperture mask on the front element which stops the lens down slightly to f/3. I found this helped tighten the stars a little and reduced some diffraction effects from lens clips. I am also using 5nm filters so being at f/3 should help negate any signal loss from band shift. As a result, I don’t think I am losing much imaging speed with the mask when using the narrowband filters. I probably should do a bit more testing to see if an even smaller mask would have the same effect.
. As you know, 
....I wonder what will be possible in the coming years...
. I'm glad you noticed the star field as I did try a few different versions, but decided to keep the stars more subdued to allow the more subtle narrowband emission features to be the star, as it were 
). I ended up a 2.94GB master RGB .xisf to work with 
