Starship Asterisk*

a.niwa wrote:
You can confirm the intruder galaxy in the Hubble WEB site as follows,
http://hubblesite.org/gallery/tours/tour-tadpole/
Click play Movie > Click Distorted Shape > Click continue

the Tadpole Galaxy will likely lose its tail as it grows older, the tail's star clusters forming smaller satellites of the large spiral galaxy.

ems57fcva wrote:As best I can tell, the small galaxy at the bottom of the photo IS the intruder galaxy. There is a bridge running between the cores of the two galaxies! It comes out of the central code at 6:00, sweeps up past the 2:00 position (where what I think is a tidal tail is being mistaken for the intruder), continues above Arp 188 and then dives down in front of Arp 188 towards a point to the right of the smaller galaxy. Then it turns like a "J" and heads into the core of the smaller galaxy.

My guess is that the smaller galaxy swept past Arp 188 going just above it to form a bridge between the galaxies. It then got swung around and down towards its current position. The tidal effects create the big tidal tail and a smaller one whose remnants at 2:00 are being mistaken for the intruder. The bridge then got stretched out and twisted around by the path the smaller galaxy took, but if you look for it, the full bridge is still there. In this case, the galaxies did not interact all that strongly and are now separating with their identities intact. The bridge is disintegrating as the galaxies continue to separate.

These bridges are something that I keep finding in cases of colliding galaxies, but I have never seen them modeled. There is something fundamental that we don't understand about interacting galaxies IMO.

Ann wrote:

ems57fcva wrote:As best I can tell, the small galaxy at the bottom of the photo IS the intruder galaxy. There is a bridge running between the cores of the two galaxies! It comes out of the central code at 6:00, sweeps up past the 2:00 position (where what I think is a tidal tail is being mistaken for the intruder), continues above Arp 188 and then dives down in front of Arp 188 towards a point to the right of the smaller galaxy. Then it turns like a "J" and heads into the core of the smaller galaxy.

My guess is that the smaller galaxy swept past Arp 188 going just above it to form a bridge between the galaxies. It then got swung around and down towards its current position. The tidal effects create the big tidal tail and a smaller one whose remnants at 2:00 are being mistaken for the intruder. The bridge then got stretched out and twisted around by the path the smaller galaxy took, but if you look for it, the full bridge is still there. In this case, the galaxies did not interact all that strongly and are now separating with their identities intact. The bridge is disintegrating as the galaxies continue to separate.

These bridges are something that I keep finding in cases of colliding galaxies, but I have never seen them modeled. There is something fundamental that we don't understand about interacting galaxies IMO.

Personally I doubt that the small disk galaxy has anything to do with Arp 188. I believe, instead, that the disk galaxy near the bottom of the picture is a background object. It is very well-formed and bright, and its disk has symmetric dust lanes and star formation. Its appearance makes it resemble our large galactic neighbour, the Andromeda galaxy. Such well-formed and symmetric galaxies are almost always big, but if this galaxy is so close to Arp 188 that it has collided with it, then it must be small indeed. I find that extremely unlikely. Instead, I think that it is a big spiral galaxy that is many millions of light-years further away from us than Arp 188.

Also, if this galaxy had actually collided with a galaxy that was as big as itself or even bigger, then its symmetric shape would be completely ruined. This galaxy is simply much, much too well-formed to have had a recent close encounter with a galaxy larger than itself.

Indeed, when you take a close look at the "tail" that seems to emanate from the center of this spiral galaxy, it becomes obvious that the tail instead emanates from the small round galaxy at its lower right. The "tail" is in fact two long star streams emerging from opposite sides of the small galaxy.

But Arp 188 does indeed have a tail pointing downwards. Follow the tail down, and you'll come to a small round shape at the upper right of the small bright spiral galaxy. This small round object could indeed be a dwarf galaxy, a so-called dwarf spheroidal, that is interacting with Arp 188. This object and Arp 188 actually resemble the Andromeda galaxy and its dwarf spheroidal companion NGC 205.

Ann

Roland wrote:I see a different story. The intruder galaxy is the one in the lower right. The trajectory path is as you say comming in from the foreground and above arp188, but then it traveled across and downward behind. I can see the haze trail leading to galaxy below. I can also see that the galaxy has been captured and is returning for another pass. It has a faint trail of haze showing its changing direction.

Chris Peterson wrote:I think you are demonstrating more about how the mind works than about how galaxies work, given that it's doubtful any of these things can be determined visually from a single image. In actuality, most of what is known about the positions and movement of these bodies probably comes from Doppler shift data acquired with spectral studies.

mike bischot wrote:It looks like the bottom right of this composite picture has a few frames that are the same. Can the editor confirm this?