M 31 Repro

[marco]

Hi all, it has been few weeks I started playing with Pixinsight and I have to say I am really hooked with it. It has not the most intuitive interface but some of the function available are really amazing. In particular I like the way it can manage high dynamic and compress it working always with 32 bit files, something that PS cannot do.

I decided so to reprocess a picture I took some years ago (in 2008) when I was still imaging from Italy the few times I was back home. I took back so the original composed fits files of M31, a target that is very difficult in Australia because the low elevation but that transit at zenith in Italy, taking advantage so of best trsparency and lowest light pollution damage. At that time I couldn't expose for long time since I could take advantage of only a handful nights per year, therefore the total exposure is "only" 5 hours. I had the good idea to take a mix of "long" subframes (10 mins each) and shorter frames (3 mins each) to recover all details from the core.

Here is the result of the new blending:
(http://www.glitteringlights.com/Images/deepsky/13667287_7Mtr58#982237200_3RbCV-X3-LB)http://www.glitteringlights.com/Images/deepsky/13667287_7Mtr58/982241589_#1511603464_qz4qtMT-X3-LB

As usual I also add the full res / full screen version visible here:
http://astrosurf.com/lorenzi/ccd/M31_HaLRGB.htm

Here is for comparison the old version:
http://astrosurf.com/lorenzi/ccd/M31_HaLRGB_big.jpg

Processing was done using both Pixinsight (mostly on removing gradients and processing the luminance/Ha) and Photoshop (color calibration and saturation and final touch up). It is amazing to me the difference that 3 years of more experience in image processing combined with new tools can produce in the final result.

Hope you will like it
Clear Skies
Marco

[Ross G]

Hi Marco,

What an amazing photo!

Such amazing detail and beautiful colours.

I love the scattered red areas.

Thanks.

Ross.

[Octane]

Awesome work, my man.

Makes me realise the colour balance in mine is all wrong. I've been capturing some hydrogen alpha, and, will be adding that to mine and do a proper job of processing it.

And, yes, PixInsight is tres uber awesome. :D

H

[gregbradley]

That's a stunner. My only comment is the Ha areas are too candy coloured and look out of whack with the relative colour of the rest of the image,they seem overemphasised. Just my personal taste. A sensational image and I can see the unique high dynamic range nature of the image you mention you achieved using Pixinsight.

A massive improvement over the original.

Greg.

[jase]

Very nice work Marco. A great comparison showing off some cool features of PI. Have to say, one thing that bugs me with PI is that of FITS data movement from CCDStack to PI, it seemsto flip image orientation. Its as though PI reads the format differently...anway I digress. Excellent image. Thoroughly enjoyed it.

[iceman]

Beautiful image! I agree with Greg about the red areas - seem overly pink, but a stunning view!

[Martin Pugh]

Marco
you've certainly revealed structure at the core of M31 not often seen.
Good work.

BTW, CS5 has a newish feature called HDR which can treat an image that has a high dyanamic range, and reveal structure right down to the core.....with the right 'custom' settings of course.

Martin

[Paul Haese]

Marco, very nice image and the colour saturation is pretty good. Like Greg I think the Ha areas are a little too pink magenta. Other than that it is a lovely image. One I would love to have myself.

[gregbradley]

Just out of curiousity, would you call M31 a spiral galaxy? Are the arms obscured by its angle relative to us?

It doesn't really look like many other galaxies in that it seems to circular with no spiral structure. Perhaps more like Sombrero Galaxy.

Greg.

[marco]

Thanks Ross!



Thanks Martin. I know the HDR function of CS5 but believe me, here we are talking to a completely other level of function, try it to believe ;)



Thanks H!



Thanks Jase, I also noticed the same thing, all fits opened (and saved) by Pixinsight are flipped. I believe this is perhaps a bug of the routine they use, however it is not a big deal, perhaps nobody ever had them noticing it..



Thanks Greg, I have just corrected the Ha color reducing the saturation and a bit the balance. I also believe the former pest had the wrong coloro profile attached. Can you please check if now colors look more natural?



Thanks Paul, as per Greg please check if the new version at the link at top is correctly balanced (otherwise it is a problem of my monitor..)



Thanks Mike!

Thanks
Marco

[atalas]

Wonderful Marco!

[marco]

Thanks Louie!

Marco

[madbadgalaxyman]

Greg, I think I can answer your question as to whether M31 is actually a spiral galaxy. You are quite right to point out that most of the prominent "arm" features are actually arrayed in a giant ring, so this is more of a ring galaxy than a spiral galaxy!

It was recognized, long ago, when people made maps of the distribution of OB stars and HII regions over the face of this galaxy, and when they then deprojected M31 to a face-on orientation, that all of their "joining the dots" to make so-called "spiral arms" did not produce any plausible overall spiral structure for this galaxy.....the only valid interpretation was (and still is) that the major structure of current star formation (e.g. Molecular clouds, OB stars, HII regions, etc) in the Andromeda Galaxy is actually a ring!!

There are indeed a few minor spiral arms, but the ring structure dominates.

The ring structure may be connected with passages of close satellites such as M32 and NGC 205. Furthermore, the disk structure of M31, far from looking planar (as we would expect from the textbooks) looks to depart from planarity in several places. M31 has had a very complex history, for instance it has disturbed greatly the outer gaseous parts of M33.

best regards, robert

P.S.
I have extensive multi-wavelength imaging data showing the circular distribution of many different star formation tracers in M31, if anybody wants to investigate this further.

[madbadgalaxyman]

Marco,

As has become the normal thing in most of your astro images, there is something on your image which is potentially of astrophysical interest; due to the depth and resolution that you always do achieve in your images.

The centralmost feature of dust lanes in M31 looks like a ring ; the dust lanes spiral inwards, but they actually do form a ring structure.

In my view, if this inner dust feature were at the same orientation (the same angle to our line-of-sight) as the rest of M31, the central dust lanes would make a completely different pattern than the actual dust pattern that we do observe.

The overall dust lanes seen in M31 are foreshortened due to the orientation of the disk of this galaxy, but the central dust ring does not look foreshortened!!

The way I interpret this hypothetical dust ring is that the inner dust ring is actually in a different plane to the rest of M31.
Indeed, this is one strange galaxy, and it has had multiple interactions with other galaxies in its past.
Various subtle non-planarities are very common within M31!

The central dust feature is, without doubt, an unusual one.

Note added in an edit:
One of the more interesting observations that is within the positional accuracy possible with the Hubble Space Telescope is to measure the proper motions of M31 and its satellites. In other words, while extragalactic astronomers generally have access only to the radial motion of a galaxy (its motion in our line-of-sight), by means of its velocity as can be derived from its spectrum, it is currently feasible to measure the motions "across the sky" (at right angles to the line-of-sight) of galaxies in our Local Group of Galaxies. This remarkable feat would then enable us to get accurate orbits for many nearby galaxies such as M32 and NGC 205; some people think that a lot of the strange and unusual features of M31 are due to the effects of its satellite galaxies.

[madbadgalaxyman]

Just a quick note regarding the non-planar nature of M31. A sequence of images at various depths, showing the various changes (twists or bends) in the position angle of this galaxy, at various galactocentric radii, can be found in my recent thread in the "Astronomy and Amateur Science" forum.

As per that thread, I noted that F.Schweizer reported a disk-bulge misalignment of 10 degrees....is this plausible?

Yes, M31 is definitely a peculiar galaxy.....it is distinctly unusual compared to most spirals of a similar Hubble type!

Note added in a later edit:

The Andromeda Galaxy has now been observed at "most every wavelength". I intend to present a multi-wavelength imaging view of this unusual galaxy in the "Astronomy and Amateur Science" section.
Interestingly, perhaps the most informative image, a high resolution Near-infrared image, was only made recently in an MSc thesis by Jonathan N. Sick of Queens University (canada). Together with the WISE satellite images in the NIR, it clearly shows that even the massive "backbone" of old stars within M31 is disturbed.