Author Topic: Wanted! Galaxy pairs which overlap but are not merging  (Read 592202 times)

NGC3314

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Re: Wanted! Galaxy pairs which overlap but are not merging
« Reply #9900 on: June 30, 2014, 08:56:08 pm »
I've caught up with overlapping systems from the forum now (going back to my previous harvest in last 2012!), with some urgency since there is a possibility of getting certain kinds included in a Hubble "snapshot" project (more on that if it happens). Eliminating duplicates with the earlier list, this got something like 112 new pairs. I'll attach a text file of the ones newly included, in the same format as earlier text catalogs except that I use DR8-10 ObjIDs which are one digit longer. The SDSS name and ObjID are, for uniformity, those of the brighter member of each pair. There is also a final column with the poster (and date) where I found the system in this thread. (Truth in advertising - I couldn't reach the DR10 server over the weekend so redshifts are only complete as of DR9).

Now I head over to Talk and look for additional good candidates among the hashtags.

One more thing - I attach a second text file listing the SDSS objects in this update in a format that can be pasted into one of the  the image tools (like the DR8 version here and generate pages of clickable thumbnails, for a quick overview of the systems. I'm still struck that the most spectacular of these has a foreground galaxy, IC 284, which is so large and diffuse that the SDSS photometric pipeline seems not to have picked it up, although a bunch of foreground stars are found.

zutopian

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Re: Wanted! Galaxy pairs which overlap but are not merging
« Reply #9901 on: July 01, 2014, 03:00:47 pm »
Thanks for the update! In your post, there are mentioned two attachments, but there is just one!

NGC3314

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Re: Wanted! Galaxy pairs which overlap but are not merging
« Reply #9902 on: July 02, 2014, 01:06:26 am »
Let me try this again - this should be the text catalog listing of the "new" objects.

JeanTate

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Re: Wanted! Galaxy pairs which overlap but are not merging
« Reply #9903 on: July 07, 2014, 07:35:50 pm »
How does passage through a foreground galaxy affect radio emissions from a background source? is a thread I just started, in RGZ Talk. It may be of some interest to zooites who read this thread too.

zutopian

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Re: Wanted! Galaxy pairs which overlap but are not merging
« Reply #9904 on: July 08, 2014, 03:02:28 pm »
Copy from another topic:

We've been trying to get Hubble images of some of the Galaxy Zoo overlapping-galaxy pairs for about 5 years now. The program has finally borne fruit - this cycle, a program led by Benne Holwerda was approved. I attribute this in part to his clever formation of the acronym STARSMOG[1] for the project. Another selling point was selection of pairs already known to be at very different redshifts so they can't be interacting with each other and therefore possible distorted). The list of target galaxies so far looks like it will be roughly half Galaxy Zoo finds and half pairs selected from the GAMA redshift survey (these samples do, umm, overlap a good bit). This is a so-called snapshot program - projects using relatively brief observations, typically 30 minutes or less, which can be slotted in between longer ones to fill out gaps in the telescope schedule given it pointing constraints. So we are allowed to send a list of 150 potential targets with no actual guarantee which or how many will be observed; recent years' results suggest we'll get about 50 images.

The science goal is a set of dust-attenuation maps of the foreground spirals, looking only at pairs that have a smooth background system. Among other things, this will inform analysis of supernova luminosities and improve our zero point for the evolution of dust effects with cosmic time (with Hubble Zoo overlaps forming the rest of that effort).

Getting each new data set for this project will be, in the words of a famous (albeit fictional) resident of this state, like a box of chocolates. We never know what we'll get.

[1] STarlight Absorption Reduction through a Survey of Multiple Occulting Galaxies ("reduction" in the sense that the results will allow us to reduce the uncertainties due to this absorption)

Congrats!

elizabeth

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