Interesting phenomenon. I need some explanations, if any available.

by Benescu

I might be wrong and in this picture might be just 2 galaxies overlapping. But if they are not overlapping, is there any chance that the center galaxy feed the small yellow galaxy that's top-right of it? Also, on the bottom, the same phenomenon appears (or it might be just some optical illusion / overlapping ).
To me looks like the smaller (yellow) galaxies "feed" from the bigger brighter ones. I might be wrong. Also, I'm open to discussion.

P.S.: A more clear image might solve the mystery 😉

Posted October 21, 2015 11:31 PM
by williamaskew

Here's the SDSS link.

http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?ra=135.56771080252716&dec=27.672330380628956

Posted October 22, 2015 2:22 AM
by Benescu in response to wtaskew's comment.

Thanks. But now I'm even more confused.They do or do not interact? As is late now, I'll gonna take some sleep. First thing in the morning, I'll take a look over the graphs.

Posted October 22, 2015 3:06 AM
by Budgieye moderator

They look about the same colour, and are slightly disturbed, so they might be interacting. To be certain, we should compare the redshift to see if they are at the same distance. Luckily we have two spectra.

http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?ra=135.56771080252716&dec=27.672330380628956
http://skyserver.sdss.org/dr9/en/get/specById.asp?id=2178723578948642816

The target galaxy has a redshift of 0.088

The hydrogen and oxygen lines shows that this is an active galaxy, Something has happened to it.

http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?id=1237664837541036234

The lower galaxy has a redshift of 0.087 There is no hydrogen and oxygen peaks. It has had a boring history lately.

general information on charts

7.1 Spectral Charts http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=7&comment_id=53d8bb480d43f77b9e000fb7

7.2 Redshift z and photometric Z (PhotoZ) http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=7&comment_id=53d8bb78db90c70a2a000c0a

7.3 Measure distance http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=7&comment_id=53d8bb6c0d43f776b00010af

How far apart are these galaxies?

http://www.wolframalpha.com/input/?i=cosmological+redshift&a=*C.cosmological+redshift-_*Formula- and click on formula

The target galaxy is 1.20 billion light years away.

The other galaxy is 1.19 billion light years away.

So they are separated by 0.01 billion light years , or 10 million light years. This is about 5 times further than the Andromeda galaxy is from our Milky Way galaxy.

So it is likely that they are not interacting. But it is unusual to actually get two spectra from galaxies under discussion. Usually we would have to guess.

Also, it is not surprising that they galaxies are slightly fuzzy. They are 10% across the universe. 😃

Posted October 22, 2015 6:46 AM
by Benescu in response to Budgieye's comment.

Interesting explanation. Also, thanks for making some things clear to me, as I'm new here and I need to learn some stuff about reading the graphs. That helped 😉

The target galaxy is 1.20 billion light years away.
The other galaxy is 1.19 billion light years away.

Your research raised some questions in my head:
1. By target galaxy I assume you refer to the big one in the center. But with the other galaxy, you mean the small one next to center (yellow-ish one) or the big bright one at the bottom of the photo?
2. The distance of 0.01 LY is between the 2 bright ones or the one bright and the "companion" smaller one?
3. They (the bright ones) are not interacting with each other. BUT ... do they interact with the less bright ones? The "tails" suggest that they do, but this might be just a pure coincidence that they point to smaller galaxies.
I am not too familiar with such "in depth" approach of galaxies and even if my observations might sound "newbiesh" I'm open to learnings, so please be kind 😉

Posted October 22, 2015 9:46 AM
by Budgieye moderator

The other galaxy (to me) is the fuzzy one near the bottom at 5:30. I am not sure which of the blobs are stars and which are galaxies. You can search each blob in SkyServer and see if there are more spectra (very unlikely), nope

objects with a spectrum.

The distance of 10 million light years is between the two objects with spectra. This doesn't include sideways distance, which can also be calculated see Forum: Thurs Sept 27, 2012 Measuring the size of distant galaxies by Budgieye http://www.galaxyzooforum.org/index.php?topic=280432.0 using guesswork, wolframalpha and others.

Then you can click on each object and look for catalog data Stars are round, galaxies are usually not round ie. extended sources. This doesn't always work with double stars, and round galaxies.

star = round

galaxy = not round

but this data can be wrong.

labelled objects

In SkyServer you can look up the photoz of each object, which is the software guess at the z. This can be correct or amazing wrong, and the error bars can be so big that a guess at colour = distance by a Zooite is just as good.

But none look hopeful enough to spend time on it. I would think that the active target galaxy has assimilated a smaller galaxy in the past, and we can't see it now. But that is just a guess.

Posted October 22, 2015 12:11 PM
by Benescu in response to Budgieye's comment.

Great documentation. Thanks for having time to respond. Unfortunately I haven't found evidence of any interaction. Those tails might be the result of an earlier impact (on both) and the direction that they point could be just a coincidence. Maybe, one day, someone will find it interesting and have time to take a closer look on them.

Thank you again. I'd wish I have your knowledge 😄

Posted October 22, 2015 10:27 PM