APOD: Arp 78: Peculiar Galaxy in Aries (2020 Sep 18)

[APOD Robot]

Arp 78: Peculiar Galaxy in Aries

Explanation: (xxxedit and linkxxx) Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries, some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy. Also known as NGC 772, the island universe is over 100,000 light-years across and sports a single prominent outer spiral arm in this detailed cosmic portrait. Its brightest companion galaxy, compact NGC 770, is toward the upper right of the larger spiral. NGC 770's fuzzy, elliptical appearance contrasts nicely with a spiky foreground Milky Way star in matching yellowish hues. Tracking along sweeping dust lanes and lined with young blue star clusters, Arp 78's large spiral arm is likely due to gravitational tidal interactions. Faint streams of material seem to connect Arp 78 with its nearby companion galaxies.

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[Ann]

NGC 772. Image Credit & Copyright: Bernard Miller.

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I feel I should say something intelligent about this APOD, but I'm not sure what. NGC 772 has never been one of my favorite galaxies. What can I say - it looks like a big fat comma that has plopped over on its side? A big fat comma with layers upon layers of structures and halos, like an onion? 🧅

NGC 772 seems to have three satellite galaxies on one side of it, more or less in the direction of its comma-shaped arm(s). One fuzzy tidal tail of NGC 772 stretches towards the leftmost of these satellite galaxies. Just one and seemingly smaller and less massive satellite appears to be located on the opposite side of NGC 772.

That's what causes the twisty shape of NGC 772, I suppose.

Ann

[Lasse H]

I wonder what, if anything, was intended to replace the beginning of the Explanation text:
(xxxedit and linkxxx)

[Ann]

I wonder what, if anything, was intended to replace the beginning of the Explanation text:
(xxxedit and linkxxx)

I think today's APOD has been replaced. Yesterday's APOD said that tomorrow's APOD (that is, today's APOD of September 18) would be Orion in 3D. I groaned, because I just can't deal with 3D pictures.

Ann

[heehaw]

Arp 78. I don't think I ever met Chip Arp. I think it is very nice that he had such a short distinctive name; it makes lists neater. (What if he had been Cholmendsy-Fuggermeister? This galaxy would be Cholmendsy-Fuggermeister 78 ! )

[JohnD]

Cholmendsy-Fuggermeister? Not Bertie Cholmendsy-Fuggermeister? Super chap! Not Chumley-Forster, he hated that. I recall him describing this as thin layer of lemon curd...Completely made out of rubber... but then I realised that he was very, very drunk.

With apologies to Rowley Birkin.

[Ann]

Arp 78. I don't think I ever met Chip Arp. I think it is very nice that he had such a short distinctive name; it makes lists neater. (What if he had been Cholmendsy-Fuggermeister? This galaxy would be Cholmendsy-Fuggermeister 78 ! )

Camilla 'Chummy' Fortescue-Cholmondeley-Browne. Her married name was Noakes.

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Camilla 'Chummy' Fortescue-Cholmondeley-Browne, midwife of "Call the Midwife". It's a bit of a pity that she gave up her magnificent last name for Noakes when she got married.

Who knows, she may have dabbled in astronomy in her spare time. There was an episode showing Nonnatus House to be in possession of a telescope from what looked like Newton's time.

Fortescue-Cholmondeley-Browne 78. That would have been something.

Ann

[De58te]

It looks like Orion in 3d won't be ready until tomorrow. So in a bind the APOD robot turned to the past and got the picture from Jul 7, 2011. Has the same description yet the copyright is by a different man?!

[orin stepanek]

The above galaxies seem to be two far away; but something seems to be yanking on it!

[johnnydeep]

Arp 78: Peculiar Galaxy in Aries

Explanation: (xxxedit and linkxxx) Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries, some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy. Also known as NGC 772, the island universe is over 100,000 light-years across and sports a single prominent outer spiral arm in this detailed cosmic portrait. Its brightest companion galaxy, compact NGC 770, is toward the upper right of the larger spiral. NGC 770's fuzzy, elliptical appearance contrasts nicely with a spiky foreground Milky Way star in matching yellowish hues. Tracking along sweeping dust lanes and lined with young blue star clusters, Arp 78's large spiral arm is likely due to gravitational tidal interactions. Faint streams of material seem to connect Arp 78 with its nearby companion galaxies.

Here's a much prettier image of Arp 78 that Ann might like, from https://thedemon-hauntedworld.tumblr.co ... p-78-is-an - though it is much bluer! - and better shows off the streams connecting Arp 78 with it's three small (and much yellower) companions, which also seem to be comfortably "closer" in this view:

NGC 772 (also known as Arp 78) is an unbarred spiral galaxy approximately 130 million light-years away in the constellation Aries. Credits: Data obtained using the MegaCam camera on the Canada-France-Hawaii Telescope Image by Jean-Charles Cuillandre (CFHT) & Giovanni Anselmi (Coelum)

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[orin stepanek]

Arp 78: Peculiar Galaxy in Aries

Explanation: (xxxedit and linkxxx) Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries, some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy. Also known as NGC 772, the island universe is over 100,000 light-years across and sports a single prominent outer spiral arm in this detailed cosmic portrait. Its brightest companion galaxy, compact NGC 770, is toward the upper right of the larger spiral. NGC 770's fuzzy, elliptical appearance contrasts nicely with a spiky foreground Milky Way star in matching yellowish hues. Tracking along sweeping dust lanes and lined with young blue star clusters, Arp 78's large spiral arm is likely due to gravitational tidal interactions. Faint streams of material seem to connect Arp 78 with its nearby companion galaxies.

Here's a much prettier image of Arp 78 that Ann might like, from https://thedemon-hauntedworld.tumblr.co ... p-78-is-an - though it is much bluer! - and better shows off the streams connecting Arp 78 with it's three small (and much yellower) companions, which also seem to be comfortably "closer" in this view:

NGC 772 (also known as Arp 78) is an unbarred spiral galaxy approximately 130 million light-years away in the constellation Aries. Credits: Data obtained using the MegaCam camera on the Canada-France-Hawaii Telescope Image by Jean-Charles Cuillandre (CFHT) & Giovanni Anselmi (Coelum)

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Good catch Johnny! Clearly shows the yankers! Something else seems to be involved also!

[johnnydeep]

Arp 78: Peculiar Galaxy in Aries

Explanation: (xxxedit and linkxxx) Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries, some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy. Also known as NGC 772, the island universe is over 100,000 light-years across and sports a single prominent outer spiral arm in this detailed cosmic portrait. Its brightest companion galaxy, compact NGC 770, is toward the upper right of the larger spiral. NGC 770's fuzzy, elliptical appearance contrasts nicely with a spiky foreground Milky Way star in matching yellowish hues. Tracking along sweeping dust lanes and lined with young blue star clusters, Arp 78's large spiral arm is likely due to gravitational tidal interactions. Faint streams of material seem to connect Arp 78 with its nearby companion galaxies.

Here's a much prettier image of Arp 78 that Ann might like, from https://thedemon-hauntedworld.tumblr.co ... p-78-is-an - though it is much bluer! - and better shows off the streams connecting Arp 78 with it's three small (and much yellower) companions, which also seem to be comfortably "closer" in this view:

NGC 772 (also known as Arp 78) is an unbarred spiral galaxy approximately 130 million light-years away in the constellation Aries. Credits: Data obtained using the MegaCam camera on the Canada-France-Hawaii Telescope Image by Jean-Charles Cuillandre (CFHT) & Giovanni Anselmi (Coelum)

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Good catch Johnny! Clearly shows the yankers! Something else seems to be involved also!

tumblr_mu1dgt2PWv1re0fwgo1_1280.jpg

I believe that would be the fourth small companion that Ann pointed out above, and to which that more diffuse stream might lead?

Four companion galaxies to Arp 78

And here's an annotated image that names it!

Arp 78 - NGC 772 - LRGB - annotated

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And a close up:

Arp 78 [NGC 770 And Three Named Companions

[johnnydeep]

Arp 78: Peculiar Galaxy in Aries

Explanation: (xxxedit and linkxxx) Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries, some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy. Also known as NGC 772, the island universe is over 100,000 light-years across and sports a single prominent outer spiral arm in this detailed cosmic portrait. Its brightest companion galaxy, compact NGC 770, is toward the upper right of the larger spiral. NGC 770's fuzzy, elliptical appearance contrasts nicely with a spiky foreground Milky Way star in matching yellowish hues. Tracking along sweeping dust lanes and lined with young blue star clusters, Arp 78's large spiral arm is likely due to gravitational tidal interactions. Faint streams of material seem to connect Arp 78 with its nearby companion galaxies.

As a followup to my already too long last post, here's a much better annotated image of Arp 772 naming all four companion galaxies previously noted from https://magnitude-alpha.forumactif.com/ ... 72-astro31 (it's a PNG, so I had to upload my own JPG version of it):

NGC 772 And Neighbors

[Chris Peterson]

Arp 78: Peculiar Galaxy in Aries

Explanation: (xxxedit and linkxxx) Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries, some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy. Also known as NGC 772, the island universe is over 100,000 light-years across and sports a single prominent outer spiral arm in this detailed cosmic portrait. Its brightest companion galaxy, compact NGC 770, is toward the upper right of the larger spiral. NGC 770's fuzzy, elliptical appearance contrasts nicely with a spiky foreground Milky Way star in matching yellowish hues. Tracking along sweeping dust lanes and lined with young blue star clusters, Arp 78's large spiral arm is likely due to gravitational tidal interactions. Faint streams of material seem to connect Arp 78 with its nearby companion galaxies.

As a followup to my already too long last post, here's a much better annotated image of Arp 772 naming all four companion galaxies previously noted from https://magnitude-alpha.forumactif.com/ ... 72-astro31 (it's a PNG, so I had to upload my own JPG version of it):


ngc-7715.jpg

It is unclear whether any of these galaxies except for NGC 770 are actual companion galaxies to NGC 772, or have any gravitational influence on it.

[johnnydeep]

Arp 78: Peculiar Galaxy in Aries

Explanation: (xxxedit and linkxxx) Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries, some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy. Also known as NGC 772, the island universe is over 100,000 light-years across and sports a single prominent outer spiral arm in this detailed cosmic portrait. Its brightest companion galaxy, compact NGC 770, is toward the upper right of the larger spiral. NGC 770's fuzzy, elliptical appearance contrasts nicely with a spiky foreground Milky Way star in matching yellowish hues. Tracking along sweeping dust lanes and lined with young blue star clusters, Arp 78's large spiral arm is likely due to gravitational tidal interactions. Faint streams of material seem to connect Arp 78 with its nearby companion galaxies.

As a followup to my already too long last post, here's a much better annotated image of Arp 772 naming all four companion galaxies previously noted from https://magnitude-alpha.forumactif.com/ ... 72-astro31 (it's a PNG, so I had to upload my own JPG version of it):


ngc-7715.jpg

It is unclear whether any of these galaxies except for NGC 770 are actual companion galaxies to NGC 772, or have any gravitational influence on it.

I suppose you’re right, but the coincident trails sure are suggestive. But of course, “coincidence is not necessarily causation”.

[Chris Peterson]

As a followup to my already too long last post, here's a much better annotated image of Arp 772 naming all four companion galaxies previously noted from https://magnitude-alpha.forumactif.com/ ... 72-astro31 (it's a PNG, so I had to upload my own JPG version of it):


ngc-7715.jpg

It is unclear whether any of these galaxies except for NGC 770 are actual companion galaxies to NGC 772, or have any gravitational influence on it.

I suppose you’re right, but the coincident trails sure are suggestive. But of course, “coincidence is not necessarily causation”.

Actually, I think the coincident trails are suggestive of their not being related. These kinds of trails happen because of collisions or near collisions, and don't typically point towards the colliding body. And having more than one interaction during the relatively short time that tidal tails persist is very unlikely. Our eyes see patterns... even when they're not there. My bet is this is the result of a single interaction that occurred fairly recently, between NGC 772 and NGC 770.

[johnnydeep]

It is unclear whether any of these galaxies except for NGC 770 are actual companion galaxies to NGC 772, or have any gravitational influence on it.

I suppose you’re right, but the coincident trails sure are suggestive. But of course, “coincidence is not necessarily causation”.

Actually, I think the coincident trails are suggestive of their not being related. These kinds of trails happen because of collisions or near collisions, and don't typically point towards the colliding body. And having more than one interaction during the relatively short time that tidal tails persist is very unlikely. Our eyes see patterns... even when they're not there. My bet is this is the result of a single interaction that occurred fairly recently, between NGC 772 and NGC 770.

Ok, thanks. Point well taken. And to think I usually have such trouble seeing pictures in the swirling and varied forms of nebulae!