APOD: Galaxies on a String (2010 Jul 02)

[APOD Robot]

Galaxies on a String

Explanation: Galaxies NGC 5216 (top) and NGC 5218 really do look like they are connected by a string. Of course, that string is a cosmic trail of gas, dust, and stars about 22,000 light-years long. Also known as Keenan's system (for its discoverer) and Arp 104, the interacting galaxy pair is some 17 million light-years away in the constellation Ursa Major. The debris trail that joins them, along with NGC 5218's comma-shaped extension and the distorted arms of NGC 5216, are a consequence of mutual gravitational tides. The tides disrupt the galaxies as they repeatedly swing close to one another. Drawn out over billions of years, the encounters will likely result in their merger into a single galaxy of stars. Such spectacular galactic mergers are now understood to be a normal part of the evolution of galaxies, including our own Milky Way.

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[verkle2]

Perhaps this line just happens to be superimposed on another galaxy. I notice that there is a similar line moving away from the galaxy on the opposite side. Why does it have to mean that these 2 galaxies are interacting? What is the physical methods that could even take place to create such a clean line between galaxies? There are too many such questions that need to be answered before coming up with such an explanation that is given today.

[boomer12]

If there were a planet in the middle of the star lane....what an UNOBSTRUCTED view it would have!!! No dust lanes, and other walls of stars to obscure the rest of the universe....and depending on your angle to the galaxies, you would have TWO galactic black holes to study!!!! Awesome!!

[storageboy]

What caught my attention wasn't so much the "Galaxies on a String" but the number of galaxies that seem to be in background of the picture. The closer I looked the more there seemed to be. Amazing.

[orin stepanek]

The "string" seems to go through the center of the bottom galaxy and come out the other side like a tail. An illuision I suppose!

[Guest]

The 'string' connecting the gxys do not seem to be 22,000 ly. At 17m ly away, comparing the size of the gxy's to the string it seems more like 100,000+ ly.

[biddie67]

Just by looking at the picture, it seems that NGC 5216 (top) has already absorbed much of NGC 5218's material.

The use of the word "tides" in galactic interactions is so different from "tides" here on Earth where the effects of tides are so much more fluid, immediate and with the elements of obvious up/down and back and forth. While both effects are due to gravity, tides in galactic interactions seem to be more of just a steady, slow pull.

[León]

That long cord that connects the galaxies consisting of a succession of stars, which curiously remain aligned as if the piped environment, aided by gravitational stress of galaxies, but something more must happen because the phenomenon is repeated queues forming exterior sides and the same occurs in the arms of spiral galaxies.Ese largo cordel que enlaza las galaxias constituido por una sucesión de estrellas, que curiosamente permanecen alineadas como si el entorno las entubara, ayudada por la tensión gravitatoria de las galaxias, pero algo mas debe ocurrir porque el fenomeno se repite en los lados esteriores conformando colas y los mismo ocurre en los brazos de las galaxias espiral.

[Chris Peterson]

Perhaps this line just happens to be superimposed on another galaxy. I notice that there is a similar line moving away from the galaxy on the opposite side. Why does it have to mean that these 2 galaxies are interacting? What is the physical methods that could even take place to create such a clean line between galaxies?

The physical mechanism of tidal interaction is very clear, and when that mechanism is applied in numerical n-body simulations, modeled galaxy collisions produce exactly these kinds of structures. When theory and observation are in agreement, it is strong evidence that the theory is substantially correct.

[moonstruck]

Ahh, The Supreme Architect of the Universe.

[Todd Thomas]

The 'string' connecting the gxys do not seem to be 22,000 ly. At 17m ly away, comparing the size of the gxy's to the string it seems more like 100,000+ ly.

I too was curious about the 22,000 ly figure. That would make the galaxies roughly 10,000 ly in diameter, which seems really small for typical spiral and elliptical galaxies. 10,000 ly is roughly Magellanic-Cloud-sized.

[Todd Thomas]

...10,000 ly in diameter, which seems really small for typical spiral and elliptical galaxies.

Guess I need to research this more. Found this quote at http://imagine.gsfc.nasa.gov/docs/ask_a ... 1205a.html:

"Most of the galaxies in the universe are actually smaller than the Milky Way. For example, most of the dozens of galaxies in our Local Group are at least ten times smaller in diameter." -- Michael Loewenstein and David Marsden for "Ask an Astrophysicist"

[??????]

Is it just me or does it seem that APOD is recycling images.... The universe hasn't run out of cool stuff to look at yet has it?

[owlice]

This is a new image. APOD does rerun images, usually on weekends (especially Sunday). More information on that is here: http://antwrp.gsfc.nasa.gov/apod/ap_faq.html

[bystander]

Colliding galaxies
PhysOrg | Astronomy | 02 July 2010

Click to view full size image

NASA's Astronomy Picture of the Day website has published an image taken from the Mount Lemmon SkyCenter. The image, posted July 2, is that of the Keenan system of colliding galaxies and was collected during an Astronomer Night program at the observatory by Adam Block, who is also the observing programs coordinator at the SkyCenter.

"A fascinating aspect to this image is that it resembles the outcome of a computer simulation designed to demonstrate the result of galactic collisions," Block said.

"Long ago I was inspired by the work of John Dubinski and others on what are called galactic mergers. Dubinski created code that ran on a supercomputer to simulate the merger of the Milky Way, where we live, and our nearest large neighbor, the Andromeda Galaxy, to create Milkomeda," Block said.

The movie that Dubinski made, part of his GRAVITAS series, is sometimes used at the Mount Lemmon SkyCenter's program. Block said, "There is a point in the simulation where the resulting pattern looks - to my eye - very similar to NGC 5216, the Keenan system."

"Assuming that the physics are correct, it is remarkable that the universe is large enough to express examples of all potential possibilities. This lends credence to the idea that astrophysical computer simulations may be predictive," he said.

Block said the tidal stream that seems to connect the galaxies with their two counter-oriented tidal tails is represented well in the comparison. The pattern, he said, exists only briefly in the full simulation.

[ngc1535]

Perhaps this line just happens to be superimposed on another galaxy. I notice that there is a similar line moving away from the galaxy on the opposite side. Why does it have to mean that these 2 galaxies are interacting? What is the physical methods that could even take place to create such a clean line between galaxies? There are too many such questions that need to be answered before coming up with such an explanation that is given today.

HI,

You really need to watch the animation/visualization for this N-body code. Gravity, for all of its simplicity, makes the most remarkable structures in our Universe.

I believe you can even watch it on a YouTube video:
http://www.youtube.com/watch?v=jbXgQaCobLc

Regards,
Adam Block

[DavidLeodis]

There is a very interesting looking hook-like blue galaxy at about 2 o'clock from NGC 5128 at about mid way between NGC 5128 and a larger blue galaxy (the larger image brought up by clicking on the APOD shows the hook-like galaxy better).

[NoelC]

In another thread, someone asks:

I just wondering what is it at (13:32:39, 62°42’52″). Is it a supernova? The object does not exist on DSS nor SDSS surveys. Thanks.

Ooh, I love questions like this.

This is the object to which you are referring, no?



I pulled POSS2 plate data from the DSS, and you're right, it doesn't show there:



Looking very closely and critically at it, it's too soft to be a point light source. And it's more symmetrical than most of the rest of the objects in the image.

If I had to guess I'd say it was a processing mistake - possibly an accidental click of a paintbrush tool on the image. Or possibly something put there on purpose to help identify the image if it should be repurposed.

-Noel

[ngc1535]

In another thread, someone asks:

I just wondering what is it at (13:32:39, 62°42’52″). Is it a supernova? The object does not exist on DSS nor SDSS surveys. Thanks.

Ooh, I love questions like this.

This is the object to which you are referring, no?



I pulled POSS2 plate data from the DSS, and you're right, it doesn't show there:



Looking very closely and critically at it, it's too soft to be a point light source. And it's more symmetrical than most of the rest of the objects in the image.

If I had to guess I'd say it was a processing mistake - possibly an accidental click of a paintbrush tool on the image. Or possibly something put there on purpose to help identify the image if it should be repurposed.

-Noel

DARN IT! BLAST IT!
(I hate when that happens).
Yes. that appears to be a mouse click with the paint brush.
I probably inadvertently clicked on the image when I was preparing the JPEG for the web. It is NOT in any of my data.
Sorry.
Good eyes for those that found this.

Regards,
Adam Block

[ngc1535]

And I typed that so fast I left out words. Sorry again.
Yes, that appears to be a mouse click with the paint brush.
I probably inadvertently click on the image when I was preparing the JPEG for the web....
Adam

[ngc1535]

clicked... (I give up)

[astro800]

In another thread, someone asks:

I just wondering what is it at (13:32:39, 62°42’52″). Is it a supernova? The object does not exist on DSS nor SDSS surveys. Thanks.

DARN IT! BLAST IT!
(I hate when that happens).
Yes. that appears to be a mouse click with the paint brush.
I probably inadvertently clicked on the image when I was preparing the JPEG for the web. It is NOT in any of my data.
Sorry.
Good eyes for those that found this.

Regards,
Adam Block

Ah, c'mon. I thought I just discovered new type of supernova. The fuzzy one
BTW, you can instantly overlay DSS, SDSS and other images over any astronomical image on a web page by entering following URL in browsers address line:

Code: Select all

javascripta=document.createElement('script');a.src='http://sky-map.org/js/astroOverlay';a.onload=function(){astroOverlay()};document.body.appendChild(a);void+0

(it doesn't work in MS Internet Explorer only)

[ngc1535]

That is a very nice tool. Thank you for posting it. I wish it would better attribute image sources though...
I have fixed the images on my website. I can't do anything about the images that are now "out there" in cyberspace.

I am still recovering from this mortifying incident. It is, however, an interesting feeling to know someone is looking that closely to my work.

Adam

[NoelC]

No worries Adam. It's an easy mistake to make.

-Noel

[harry]

G'day

The bottom Galaxy had formed a dipole jet and one has connected with the above galaxy.

The bottom jet has twisted because of the dual gravity pulled by the top galaxy and its own galaxy core.

These type of jets are normal and observable

Chandra Observes Cosmic Traffic Pile-Up In Energetic Quasar Jet
http://chandra.harvard.edu/press/00_rel ... 3c273.html

and
Spectacular X-ray Jet Points Toward Cosmic Energy Booster
http://chandra.harvard.edu/press/00_rel ... 00pic.html

and
"Death Star" Galaxy Black Hole Fires at Neighboring Galaxy
http://hubblesite.org/newscenter/archiv ... s/2007/37/