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VV 340: A Cosmic Exclamation Point
VV 340
VV 340

  • VV 340 contains a pair of interacting galaxies that are destined to merge.

  • The Chandra data shows that the northern galaxy contains an obscured and rapidly growing supermassive black hole.

  • Data from other observatories shows that the two galaxies are evolving at different rates.

VV 340, also known as Arp 302, provides a textbook example of colliding galaxies seen in the early stages of their interaction. The edge-on galaxy near the top of the image is VV 340 North and the face-on galaxy at the bottom of the image is VV 340 South. Millions of years later these two spirals will merge — much like the Milky Way and Andromeda will likely do billions of years from now. Data from NASA's Chandra X-ray Observatory (purple) are shown here along with optical data from the Hubble Space Telescope (red, green, blue). VV 340 is located about 450 million light years from Earth.

Because it is bright in infrared light, VV 340 is classified as a Luminous Infrared Galaxy (LIRG). These observations are part of the Great Observatories All-Sky LIRG Survey (GOALS) combining data from Chandra, Hubble, NASA's Spitzer Space Telescope and Galaxy Evolution Explorer (GALEX) and ground-based telescopes. The survey includes over two hundred LIRGs in the local Universe. A chief motivation of this study is to understand why LIRGs emit so much infrared radiation. These galaxies generate energy at a rate that is tens to hundreds of times larger than that emitted by a typical galaxy. An actively growing supermassive black hole or an intense burst of star formation is often invoked as the most likely source of the energy.

Work on the full GOALS survey is ongoing, but preliminary analysis of data for VV 340 provides a good demonstration of the power of observing with multiple observatories. The Chandra data show that the center of VV 340 North likely contains a rapidly growing supermassive black hole that is heavily obscured by dust and gas. The infared emission of the galaxy pair, as observed by Spitzer, is dominated by VV 340 North, and also provides evidence for a growing supermassive black hole. However, only a small fraction of the infrared emission is generated by this black hole.

By contrast most of the ultraviolet and short wavelength optical emission in the galaxy pair — as observed by GALEX and HST — comes from VV 340 South. This shows that VV 340 South contains a much higher level of star formation. (The Spitzer and GALEX images are not shown in the composite above because they strongly overlap with the optical and X-ray images, but they are shown in a separate composite image (below). VV 340 appears to be an excellent example of a pair of interacting galaxies evolving at different rates.

These results on VV 340 were published in the June 2009 issue of the Publications of the Astronomical Society of the Pacific. The lead author was Lee Armus from the Spitzer Science Center in Pasadena, CA.

Fast Facts for VV 340:
Credit  X-ray NASA/CXC/IfA/D.Sanders et al; Optical NASA/STScI/NRAO/A.Evans et al
Release Date  August 11, 2011
Scale  Image is 2.2 arcmin across (about 285,000 light years)
Category  Quasars & Active Galaxies
Coordinates (J2000)  RA 14h 57m 00.68s | Dec +24° 37´ 02.7"
Constellation  Boötes
Observation Date  Dec 17, 2006
Observation Time  4 hours 10 min
Obs. ID  7812
Instrument  ACIS
References Armus, L. et al, 2009, PASP, 121, 559; arXiv:0904.4498
Color Code  X-ray (Purple); Optical (Red, Green, Blue)
Distance Estimate  About 450 million light years
distance arrow
Visitor Comments (17)

Re Collision between Andromeda Galaxy and the Milky Way in billions of years. I suggest it has already started. It is easy to forget Dark matter and its extension far out from the visual boundaries around galaxies.

Posted by Ulf Petersson on Saturday, 03.10.18 @ 03:51am

So in billions of years our Milky Way Spiral galaxy will do this with Andromeda? Please explain.

Posted by Tedi Davis on Tuesday, 03.4.14 @ 03:38am

But our neighboring Andromeda galaxy is still far away from this. so is it a new neighbor to our milky way?

Posted by rigel on Monday, 03.3.14 @ 06:46am

I just hope such things don't happen to our galaxy.

Posted by Hamed on Sunday, 03.2.14 @ 20:26pm

Sir, is that what is vv340?

Posted by shivani aggarwal on Sunday, 03.2.14 @ 10:00am

What is that immense X-ray source in the bottom-right part of the image?

Posted by Alexandra on Sunday, 03.2.14 @ 09:39am

I love things like this. But I really wish to be there with the science staff. I have real dream.

Posted by christopher on Wednesday, 08.22.12 @ 21:45pm

It is very beautiful.

Posted by Mary on Thursday, 08.25.11 @ 06:54am


Posted by madhushan on Friday, 08.19.11 @ 02:54am

Good Day,
Making a logical analysis and is practically anointed.
These galaxies may even enter phase melting. But the position between them and the type of ray emission, suggest that one comes from another, VV 340 south is the mother (the source of creative energy) of VV 340 north.

Posted by carlos tatis on Thursday, 08.18.11 @ 09:03am

Fascinating indeed.

Posted by Gemini on Wednesday, 08.17.11 @ 16:48pm

If the universe is expanding and everything in it is moving away from each other, how can there be collisions?

Posted by Ty Harding on Wednesday, 08.17.11 @ 16:36pm

The infrared and ultraviolet composite image makes me wonder: here, this is not a matter of approaching and receding objects (since they are about colliding), rather, it is "a much higher level of star formation". Could the redshift be apparent in some cases?

Posted by Manuel on Tuesday, 08.16.11 @ 16:55pm

Howdy... Hello... Arp had a section of his work early on in the last century, called ir-regular galaxies. One of the objects was labeled NGC 3561. I really like this object. Could you do a piece on it and other structure similar to it? Thank You

Posted by J.J.Madson on Tuesday, 08.16.11 @ 11:38am

Sir, I received your email/newsletter. Thank you very much.

Posted by Dhiraj on Saturday, 08.13.11 @ 02:43am

Since this took place 450 million years ago, might it be possible to fast forward the image to see what might be happening now?

Posted by dbooth on Thursday, 08.11.11 @ 15:59pm

Is that Infrared harmful to the EARTH in future...???

Posted by Tarun on Thursday, 08.11.11 @ 13:53pm

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