Starship Asterisk*

NGC 6240: Merging Galaxies

Explanation: NGC 6240 offers a rare, nearby glimpse of a cosmic catastrophe in its final throes. The titanic galaxy-galaxy collision takes place a mere 400 million light-years away in the constellation Ophiuchus. The merging galaxies spew distorted tidal tails of stars, gas, and dust and undergo fast and furious 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 and soon, only one large galaxy will remain. This dramatic image of the scene is a composite of narrowband and near-infrared to visible broadband data from Hubble's ACS and WPC3 cameras, a view that spans over 300,000 light-years at the estimated distance of NGC 6240.

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If Life existed in either galaxy prior to the collision, is it likely to exist now? . . .GOD ! ! ! What a Show ! !

Guest wrote:If Life existed in either galaxy prior to the collision, is it likely to exist now? . . .GOD ! ! ! What a Show ! !

Maybe, maybe not. It depends on a lot of factors, particularly what impact the collision had on the exact segment of the galaxy where the inhabited planet was located. Of course, the collision "unfolds" over millions of years, and the effects of the collision also "evolve". I guess it also depends on how hardy the life forms were, and what characteristics the planet had that made it habitable.

Nice image! We have recently seen a similar picture posted in the Recent Submissions folder. I'm too lazy to look it up right now, but is it the same picture?

Ann

Here it is
http://asterisk.apod.com/viewtopic.php? ... 25#p243482

Guest wrote:If Life existed in either galaxy prior to the collision, is it likely to exist now? . . .GOD ! ! ! What a Show ! !

What is the function of black matter in the collision ? (please excuse my english)

a number of spiral galaxies appear in the distant background. at lower right on the enlarged image a face on m101 type of spiral galaxy may be discerned - only a section of the spiral appears. the distant background soiral galaxies are the reason why the hubble space telescope must continue to operate indefinitely mapping the galactic bodies of the celestial deep.

an observer has speculated about the possibility of life existing after the merge of the two bodies comprising ngc 6240. i wish to elaborate on that issue. in my uneducated guess any life existing on either of the two merging galaxies would be elated about the increase in fireworks during and after the merge. since galactic matter consists primarily of dust and gas a merge of two or more galactic bodies would very likely be a peaceful event. the increase in brightness must be due to clouds of gas and dust being compressed to form new stellar material. the dynamics of larger material such as space rock and asteroidal debris probably influences galactic merge to an appreciable extent although impacts of larger bodies must be much rarer. any earth like planet bearing life during such a galactic merge would probably suffer only from prolonged meteor impacts and encounters with asteroids and comets.

intelligent beings populating such a planet probably would not be disturbed by an increase of celestial activity in their area. in fact, they would welcome it. a meteor storm or asteroid impact delivers precious minerals to the surface of a planet resulting in renewal of the elenents and replenishment of an atmosphere.

the earth and mars and venus are expected to benefit from an increase in meteoritic activity within the next few years, but not from a galactic merge. dust and rocky material sweeping across the galactic plane should probably enter the solar system at about this time.

What is the function of black matter in the collision ? (please excuse my english)

http://apod.nasa.gov/apod/ap080823.html

I think this is one of most impressive Hubble images in recent years that almost has the same emotional impact as seeing the HST images of M82 and NGC 1300 nearly 10 years ago!

Can any of our celestial physicists post the mechanics of two black holes colliding/merging? I would think the density of the objects would make it prohibitive?

What does this galaxy look like using an earthbound telescope? Is it visible. This is spectacular!

sheriffofnothingham wrote:i wish to elaborate on that issue. in my uneducated guess any life existing on either of the two merging galaxies would be elated about the increase in fireworks during and after the merge. since galactic matter consists primarily of dust and gas a merge of two or more galactic bodies would very likely be a peaceful event.

The bright areas represent large regions of new star formation, where hydrogen clouds have collided. You wouldn't want to be in those areas. Many high mass stars are created, which have very short lifetimes and end in violent supernovas, which result in a radiation environment not healthy for life around nearby stars. And the stellar density can be quite high in those regions, meaning that planetary systems can be disrupted and orbits changed. That's almost certainly fatal for any complex life on those planets.

intelligent beings populating such a planet probably would not be disturbed by an increase of celestial activity in their area. in fact, they would welcome it. a meteor storm or asteroid impact delivers precious minerals to the surface of a planet resulting in renewal of the elenents and replenishment of an atmosphere.

This kind of thing represents an extinction event. The sort of thing that more complex life forms tend to be eliminated by.

the earth and mars and venus are expected to benefit from an increase in meteoritic activity within the next few years, but not from a galactic merge. dust and rocky material sweeping across the galactic plane should probably enter the solar system at about this time.

No. This is not going to happen, and we would not benefit if it did.

wgf1450@gmail.com wrote:What does this galaxy look like using an earthbound telescope? Is it visible. This is spectacular!

Images made from large ground-based telescopes look similar, although with somewhat lower resolution. Visually, this object looks like just about every other galaxy: a fuzzy gray spot.

apache32 wrote:Can any of our celestial physicists post the mechanics of two black holes colliding/merging? I would think the density of the objects would make it prohibitive?

Black hole mergers are well studied (in supercomputer simulations) because they are expected to be an important source of gravitational waves detectable by new instruments just starting to come online. Basically, a pair of black holes in orbit around each other gradually lose energy to gravitational radiation and possibly other mechanisms, resulting in their spiraling into each other and merging into a single black hole with twice the mass.

Density isn't a factor. That said, if you take a black hole as everything inside the event horizon (as opposed to the assumed singularity at the center), supermassive black holes aren't particularly dense structures- similar to the density of planets, or even less.

apache32 wrote:Can any of our celestial physicists post the mechanics of two black holes colliding/merging? I would think the density of the objects would make it prohibitive?

Einstein's theory of General Relativity predicts that gravitational waves caused by the interaction of these two black holes will gradually radiate away orbital energy. As a results the black holes will slowly spiral inward towards each other until they merge.
For more info read http://en.wikipedia.org/wiki/Gravitational_wave

According to this old APOD http://apod.nasa.gov/apod/ap021128.html they are getting closer to each other, now at a mere 3000 or so light-years. Don't hold your breath though, it'll be while before the fireworks start.

When two black holes merge, does the matter in one of the holes, actually, escape it's gravity to merge into the other until it is drained? That seems to defy the definition of a black hole. Or does it happen all-at-once (ie - the larger one swallows the smaller one, whole)? Like a hole-in-one.

Tszabeau wrote:When two black holes merge, does the matter in one of the holes, actually, escape it's gravity to merge into the other until it is drained? That seems to defy the definition of a black hole. Or does it happen all-at-once (ie - the larger one swallows the smaller one, whole)? Like a hole-in-one.

There is lots of information about black hole mergers available on the Internet, presented at all levels. Many professional papers, as well.

Nothing escapes one and moves to another. Once their event horizons overlap, they are essentially one black hole with a non-spherical horizon. The black holes themselves- whether seen as particles or true singularities- merge into a new black hole in a way that is probably analogous to a particle collision.

Some more coolness around black holes merging....

Black Hole Merger Simulation showing magnetic fields and gravitational waves:
https://www.youtube.com/watch?v=GVds0q0y5RM

Gravitational Lensing, including Black Hole merger video:
http://www.black-holes.org/the-science- ... al-lensing

And some say a black hole merger may for a brief moment result in a naked singularity (this one breaks my brain):
http://en.wikipedia.org/wiki/Naked_singularity

Black holes merging. Not something you see every day. Oh – that's right we can't see it. Not something you see the results of every day. When will it happen? Oh – it may have already happened depending where you are. Soon? Now that's a question of time.

Cosmology – Not for the faint of brain but one can imagine somewhere sometime somehow something will figure it out. Maybe it already has on another planet around Barnard's star also in the non-Zodical constellation of Ophiuchus. After all it's been around a lot longer than our sun and I don't think extra-solar planets have been ruled out. http://en.wikipedia.org/wiki/Barnard's_Star

Ron-Astro Pharmacist wrote:Black holes merging. Not something you see every day.

They happen pretty often. Every day, in fact. Estimates are from one to a hundred every million years for a Milky Way size galaxy. When Advanced LIGO comes on line, the nominal estimate for detections is 40 per year.

wgf1450@gmail.com wrote:What does this galaxy look like using an earthbound telescope? Is it visible. This is spectacular!

I haven't seen this myself, but here is a good observation report:
http://observing.skyhound.com/archives/ ... _6240.html

Like most "deep sky" objects, seeing any detail at all is considered a success!

After 400 million years have the two Galaxies completed the merger?

Tctampa81 wrote:After 400 million years have the two Galaxies completed the merger?

In almost every reasonable interpretation, they are as we see them. Because time and space are tied together, and "now" is generally defined by the speed of light.

It would be better to ask what this particular collision will look like in 400 million years.

Chris Peterson wrote:When Advanced LIGO comes on line, the nominal estimate for detections is 40 per year.

Gravitational waves remain elusive though. As tricky as it is, the existing detectors should have found something by now.
What if even aLIGO can't detect gravitational waves? That's going to cause a few headaches.

If our galaxy collided with another, I assume that the matter (gas, dust, dark, etc) of both would be 'thrown about' in many and varied unpredictable ways. Although not very dense, would such matter 'thrown' in our direction be sufficient to collapse the heliosphere of our sun and magnetosphere of the earth, and expose us to the raw interstellar/intergalactic environment? And if so, (assuming we survived the other effects of the collision) would that not be fatal to us in any case?

Chris Peterson wrote:

Ron-Astro Pharmacist wrote:Black holes merging. Not something you see every day.

They happen pretty often. Every day, in fact. Estimates are from one to a hundred every million years for a Milky Way size galaxy. When Advanced LIGO comes on line, the nominal estimate for detections is 40 per year.

That's news to me. I thought they're very rare and very energetic and that no one has seen one yet.