NGC 6240: Merging Galaxies (2009 June 18)

[harry]

G'day from the land of ozzzzzz

NGC 6240: Merging Galaxies
http://apod.nasa.gov/apod/ap090618.html

NGC 6240 offers a rare glimpse of a cosmic catastrophe in its final throes. The titanic galaxy-galaxy collision is located a mere 400 million light-years away in the constellation Ophiuchus. One of the brightest sources in the infrared sky, the merging galaxies spew distorted tidal tails of stars, gas, and dust and undergo frantic bursts of star formation. The two supermassive black holes in the original galactic cores will also coalesce into a single, even more massive black hole. Soon, only one large galaxy will remain

Its not really the final throe, its part of the evolution of changing formation of galaxies.

[Chris Peterson]

NGC 6240: Merging Galaxies
http://apod.nasa.gov/apod/ap090618.html

NGC 6240 offers a rare glimpse of a cosmic catastrophe in its final throes. The titanic galaxy-galaxy collision is located a mere 400 million light-years away in the constellation Ophiuchus. One of the brightest sources in the infrared sky, the merging galaxies spew distorted tidal tails of stars, gas, and dust and undergo frantic bursts of star formation. The two supermassive black holes in the original galactic cores will also coalesce into a single, even more massive black hole. Soon, only one large galaxy will remain

Its not really the final throe, its part of the evolution of changing formation of galaxies.

Not really a catastrophe, either. Collisions like this rejuvenate large areas into star forming regions. And any planets in those galaxies with life are likely to carry on unaffected.

[neufer]

http://apod.nasa.gov/apod/ap090618.html

http://blogs.discovery.com/earth/2009/0 ... amera.html

http://www.strangescience.net/stsea2.htm

http://tinyurl.com/3d5mjs

[neufer]

Not really a catastrophe, either. Collisions like this rejuvenate large areas into star forming regions. And any planets in those galaxies with life are likely to carry on unaffected.

I'd prefer not to be in the vicinity of two X-ray emitting active galactic nuclei
doing the pasa doble, if it's all the same to you.

<<NGC 6240 is a well-studied nearby ultraluminous infrared galaxy (ULIRG) in the constellation Ophiuchus. The galaxy is the remnant of a merger between two smaller galaxies. The collision between the two progenitor galaxies has resulted in a single larger galaxy with two distinct nuclei and a highly disturbed structure, including faint extensions and loops.

The power sources of ULIRGs in general has been greatly debated. Infrared light from galaxies generally originates from dust in the interstellar medium. ULIRGs are notable in that they are abnormally bright in the infrared. The infrared dust emission in ULIRGs is over one trillion times more luminous than the Sun. Astronomers have speculated that either intense star formation regions or active galactic nuclei (which contain supermassive black holes) may be responsible for the intense dust heating that produces this emission, although the general consensus is that both may be present in most ULIRGs. Studying the exact nature of ULIRGs has been difficult, however, because the dust in the centers of these galaxies obscures both visible and near-infrared starlight and because theoretical models of both starbursts and active galactic nuclei have demonstrated that they may look similar. Because NGC 6240 is a nearby example of such a ULIRG, astronomers have studied it intensively to understand its power source.


X-ray image of NGC 6240 taken with the Chandra X-Ray Observatory, superimposed on an optical image of the galaxy.
The X-ray emission from the two active galactic nuclei can be seen as bright blue point sources. Credit: NASA.

Observations performed by Stefanie Komossa and collaborators with the Chandra X-Ray Observatory have detected strong hard X-ray emission from both of the nuclei. The intensity of this emission and the presence of emission from lowly ionized or neutral iron indicate that both of the nuclei are active galactic nuclei. Presumably, these are the black holes that were originally at the centers of the two merging galaxies. Over the course of millions of years, the two black holes are expected to come closer together and form a binary supermassive black hole.>>

[brett_w7]

Nice info on the center of NGC 6240. Also, the previous comment about the numerous star-forming regions that are likely produced by the merge process.....and the speculation that inhabited solar systems would not be affected by the merger......can't help but wonder what other fascinating things could come out of a merger.....could there be more mineral-rich star-forming regions than normal???

[orin stepanek]

There could be a few stars that got left out of the galaxy after the formation. Life forms living around such a star probably wouldn't even think of interstellar travel as the distances would be even more unreachable than they are within a galaxy.

Orin

[Chris Peterson]

I'd prefer not to be in the vicinity of two X-ray emitting active galactic nuclei
doing the pasa doble, if it's all the same to you.

Agreed. But in order to end up there, I'd think it's most likely you were near one or the other to begin with. So you're either adapted to that environment, or you weren't there in the first place to worry about it.

Anyway, if galaxies are richly inhabited by life, a collision will certainly be a bad thing for some of it. But I think most would come out largely unaffected.

[Chris Peterson]

There could be a few stars that got left out of the galaxy after the formation. Life forms living around such a star probably wouldn't even think of interstellar travel as the distances would be even more unreachable than they are within a galaxy.

You also need to consider the time scale of the collision. It happens over millions of years. If we were in the midst of such a collision, what we'd see wouldn't have changed over our history as a species, much less recorded history. It would only be in the last century that we would have developed the means to actually determine that we were in the middle of a galactic collision. And if we discovered we'd been given enough velocity to be ejected from the whole thing, it would be millions of years before we'd actually be in intergalactic space. It seems doubtful intelligent species even survive millions of years.

[bystander]

It seems doubtful intelligent species even survive millions of years.

Especially if they are as bent on self destruction as we seem to be.

[orin stepanek]

It seems doubtful intelligent species even survive millions of years.

Especially if they are as bent on self destruction as we seem to be.

It's also possible that life may not have evolved there until it was separated from the main galaxy. I wasn't considering that a life species would have survived on such an imaginary planet.
Orin

[brett_w7]

Reading these excellent thoughts almost made me forget that everything we're sensing from NGC 6240 happened 400 million years ago. Maybe the merger actually happened by now. As with all mergers, I'm sure there are disgruntled customers.

[neufer]

I'd prefer not to be in the vicinity of two X-ray emitting active galactic nuclei
doing the pasa doble, if it's all the same to you.

Agreed. But in order to end up there, I'd think it's most likely you were near one or the other to begin with. So you're either adapted to that environment, or you weren't there in the first place to worry about it.

The colliding galaxies could both have had inactive black holes at their centers
until the impinging gases from the other galaxy activated them.

• -----------------------------------------------
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  ----------------------------------------------

[Chris Peterson]

The colliding galaxies could both have had inactive black holes at their centers
until the impinging gases from the other galaxy activated them.[/list]

Yes. But active galactic nuclei mainly pump their energy out of the galactic plane, so most stars in the core should be largely unaffected. The star densities are so high in galactic cores that I suspect stable planetary systems are rare in any case, so there might not be many planets that could end up near the new AGN. I think the most likely case would be for some stable system outside the core of either galaxy to get swept into the new center- statistically unlikely, but certainly possible. And very possibly a bad thing for any life on that planet.

[harry]

G'day from the land of ozzzzz

Interactive black holes small and medium play an important part in collecting matter as they move towards the centre of the Galaxy such is the case with the Milky Way.

Millions of stellar black holes and a swarm of black holes at the centre. Search APOD for the image.