The invisible arms of NGC 1512

[strongmanmike (Michael)]

Originally Posted by RobF

Whoosh - right through the hoop. What a shot

Hey, a magenta/blue lover huh?

Cheers Rob, glad ya liked it...10hrs was long enough for me ..I will do better at some stage though

Mike

[Shiraz (Ray)]

Really outdid yourself this time Mike - what a cracker of an image, Nice that you are regularly seeing stuff that no-one else seems to.

[strongmanmike (Michael)]

Originally Posted by Shiraz

Really outdid yourself this time Mike - what a cracker of an image, Nice that you are regularly seeing stuff that no-one else seems to.

I'm deluded...but I do believe the statement in my signature

Cheers for the nice comment Ray

MIke

[nandopg]

Hi Mike,
Thank you for sharing such a stupendous image that in the end sets a new standard of reference for all of us, well at least for me.

Best Regards,

Fernando

[strongmanmike (Michael)]

Originally Posted by nandopg

Hi Mike,
Thank you for sharing such a stupendous image that in the end sets a new standard of reference for all of us, well at least for me.

Best Regards,

Fernando

Hey thanks Fernando, very glad you liked it

Mike

[cybereye (Mario)]

Mike,

What can I say - I love your work!

Another fantastic image from "La Casa di Sidonio"...

Cheers,
Mario

[SpaceNoob (Chris)]

Great image Mike, nice faint structures are clearly visible.

Sure it could do with another 10hrs, but thats enough time for a new target!

[strongmanmike (Michael)]

Originally Posted by cybereye

Mike,

What can I say - I love your work!

Another fantastic image from "La Casa di Sidonio"...

Cheers,
Mario

Thanks Mother Mario

Great image Mike, nice faint structures are clearly visible.

Cheers Chris, glad you could make'em out

Sure it could do with another 10hrs, but thats enough time for a new target!

Shhhhh don't say that mate

Mike

[broca (Steve Coates)]

Beautiful image Mike. It is crazy what you are able to pull out of these galaxies from your skies!

[marc4darkskies (Marcus)]

I guess I've been a little preoccupied! Missed this one

That's a ripper image Mike ... and I CAN see the faint arm!

Cheers, Marcus

[strongmanmike (Michael)]

Originally Posted by broca

Beautiful image Mike. It is crazy what you are able to pull out of these galaxies from your skies!

Cheers Steve and yes darker skies certainly make a lot of difference

Originally Posted by marc4darkskies

I guess I've been a little preoccupied! Missed this one

That's a ripper image Mike ... and I CAN see the faint arm!

Cheers, Marcus

He he, there are a lot of old myopic eyes out there

Mike

[David Fitz-Henr]

That's a lovely image Mike; some faint arms there with that large outer faint arm at the top looking quite impressive!
A general question / thought regarding the presence of magenta in galaxy images - given that spiral arms contain copious amounts of hydrogen as well as hot blue stars I wonder whether there should be a little magenta in these images? If the data supports it and the stars look balanced, perhaps the colour selection tool in PS should not be used that aggressively as in many images I've seen?

Anyway, looks good to me Mike

[strongmanmike (Michael)]

Originally Posted by David Fitz-Henr

That's a lovely image Mike; some faint arms there with that large outer faint arm at the top looking quite impressive!
A general question / thought regarding the presence of magenta in galaxy images - given that spiral arms contain copious amounts of hydrogen as well as hot blue stars I wonder whether there should be a little magenta in these images? If the data supports it and the stars look balanced, perhaps the colour selection tool in PS should not be used that aggressively as in many images I've seen?

Anyway, looks good to me Mike

Cheers Dave

Hey you may well be right about the magenta aaaand I have been criticized for it but in the end it is a pretty minor issue really and is more obvious to some than others. Each galaxy image seems to come together a little differently from a colour perspective, besides there is sooo much more about an image of a distant island of billions of stars with complex faint structures and jets ()...than any minor colour bias fixation

[strongmanmike (Michael)]

Here's a comparison with a deep image by the UK Schmidt

Deep Image NGC 1512

It is clear modern sensors can make small telescopes more sensitive than using chemical emulsion on very large telescopes

Mike

[RobF (Rob)]

Impressive for sure

[madbadgalaxyman (Robert)]

Very interesting, Mike.

The outer extremely-faint arms have a very unusual pattern.

The galex Far-ultraviolet band is very sensitive to the light from even relatively small numbers of hot young OB stars ( = recent star formation), so you are doing very well to pick up the blue knotty outer arms of this galaxy.

The arm pattern near the satellite galaxy is indeed distinctly weird.

This H-alpha image from the SINGG survey (with H-alpha image displayed as Orange) (H-alpha line only is coded as orange, because stellar light was subtracted from the H-alpha image) shows some of the outer arm material. The fact that the arms are luminous in Ha is proof that the knotty material consists of hot young OB stars.
Another interesting feature is that the little satellite galaxy looks bright in H-alpha, so it is likely to be very vigorously forming stars.

[glenc (Glen)]

That is an amazing image Mike.
Here are the first descriptions of NGC 1512.
https://picasaweb.google.com/1100488...28767992263970
They were made by James Dunlop in 1826 and John Herschel.
Dunlop 466 "A small faint round nebula; about 25" diameter, a little brighter in the centre: a star of the 10th or 12th magnitude preceding the nebula."
Dunlop discovered about 50 galaxies.
https://picasaweb.google.com/1100488...2146/Dunlop28#

[strongmanmike (Michael)]

Originally Posted by madbadgalaxyman

Very interesting, Mike.

The outer extremely-faint arms have a very unusual pattern.

The galex Far-ultraviolet band is very sensitive to the light from even relatively small numbers of hot young OB stars ( = recent star formation), so you are doing very well to pick up the blue knotty outer arms of this galaxy.

The arm pattern near the satellite galaxy is indeed distinctly weird.

This H-alpha image from the SINGG survey (with H-alpha image displayed as Orange) (H-alpha line only is coded as orange, because stellar light was subtracted from the H-alpha image) shows some of the outer arm material. The fact that the arms are luminous in Ha is proof that the knotty material consists of hot young OB stars.
Another interesting feature is that the little satellite galaxy looks bright in H-alpha, so it is likely to be very vigorously forming stars.

Attachment 151640

Originally Posted by glenc

That is an amazing image Mike.
Here are the first descriptions of NGC 1512.
https://picasaweb.google.com/1100488...28767992263970
They were made by James Dunlop in 1826 and John Herschel.
Dunlop 466 "A small faint round nebula; about 25" diameter, a little brighter in the centre: a star of the 10th or 12th magnitude preceding the nebula."
Dunlop discovered about 50 galaxies.
https://picasaweb.google.com/1100488...2146/Dunlop28#

Thanks for checking it out guys Seems that long outer arm is full mostly of new stars then..?

Mike

[madbadgalaxyman (Robert)]

Originally Posted by strongmanmike

Thanks for checking it out guys Seems that long outer arm is full mostly of new stars then..?

Mike

Hi Mike,
Yes, indeed....something is making those new stars in the outer regions of this galaxy, so it must therefore follow that there is lots of gas and lots of energy out there, even though there is not much visible in the outermost regions apart from the very faint and unusual arms.

I am certain (at about the 99 percent certainty level) that the outermost arm is experiencing current star formation;
there are usually O and B stars formed in a recent vigorous Star-Formation episode, and these hot young over-luminous stars:
(1) are very prominent in the far-ultraviolet, so they light up like flares in the GALEX satellite images
(2) will light up the gas in the surrounding gas clouds from which they formed, by ionizing the gas and making it glow in Ha, as it requires short wavelength ultraviolet photons from massive luminous new stars to produce an HII region.

One interesting question is, "why should stars form so vigorously, so far from the main optically-bright body of NGC 1512?"
Something has to give interstellar gas a really hard "hit or shock" in order to get it to contract and to form new stars.
So a strong shock wave is required in the outer regions of this galaxy, and also a supply of interstellar gas is needed in order to make the new stars.

It has got me speculating as to whether an encounter with the little companion galaxy might be responsible for the unusual pattern of the outer arms; but the mass difference between the primary and secondary galaxy must be significant. You really need a lot of gas and a lot of energy to make the very-luminous "new & blue" stars that are evident in the outermost arm.

Here is the Galex far-ultraviolet plus near-ultraviolet image, using the GalexView interface. FUV displays as blue, and it is almost certain that the bright knotty FUV emission of the outer arms is coming from newly-formed "hot & young" very-luminous stars.

[strongmanmike (Michael)]

Well it looks to me Robbo like something was doing burnouts and doughnuts around this galaxy and has whipped the arms into threads...perhaps the little companion galaxy is the culprit?

Mike