APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

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APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by APOD Robot » Wed Jan 10, 2018 5:07 am

Image NGC 2623: Merging Galaxies from Hubble

Explanation: Where do stars form when galaxies collide? To help find out, astronomers imaged the nearby galaxy merger NGC 2623 in high resolution with the Hubble Space Telescope. Analysis of this and other Hubble images as well as images of NGC 2623 in infrared light by the Spitzer Space Telescope, in X-ray light by XMM-Newton, and in ultraviolet light by GALEX, indicate that two originally spiral galaxies appear now to be greatly convolved and that their cores have unified into one active galactic nucleus (AGN). Star formation continues around this core near the featured image center, along the stretched out tidal tails visible on either side, and perhaps surprisingly, in an off-nuclear region on the upper left where clusters of bright blue stars appear. Galaxy collisions can take hundreds of millions of years and take several gravitationally destructive passes. NGC 2623, also known as Arp 243, spans about 50,000 light years and lies about 250 million light years away toward the constellation of the Crab (Cancer). Reconstructing the original galaxies and how galaxy mergers happen is often challenging, sometimes impossible, but generally important to understanding how our universe evolved.

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by Boomer12k » Wed Jan 10, 2018 8:03 am

Looks like a whale, coming up for air, with his head thrashing in a splash of stars....

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by Craig Porter » Wed Jan 10, 2018 9:27 am

I think there may be an error in the description, which says the galaxy "spans" 50,000 light years. The embedded link goes to another image which says the tails extend more than 50,000 light years from the nucleus, so that would make the galaxy span over 100,000 light years. One of the descriptions must be wrong.

heehaw

Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by heehaw » Wed Jan 10, 2018 10:26 am

Sure glad that OUR galaxy is not in a mix-up with another like this one is! Must be very upsetting!

NCTom

Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by NCTom » Wed Jan 10, 2018 11:11 am

Using our own galaxy as a standard, what types of radiation would be more prominent if any in such a collision than we find in our Milky Way?

heehaw

Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by heehaw » Wed Jan 10, 2018 12:42 pm

NCTom wrote:Using our own galaxy as a standard, what types of radiation would be more prominent if any in such a collision than we find in our Milky Way?
That's a good question! I really doubt that there would be any big difference.

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by De58te » Wed Jan 10, 2018 1:17 pm

Craig Porter wrote:I think there may be an error in the description, which says the galaxy "spans" 50,000 light years. The embedded link goes to another image which says the tails extend more than 50,000 light years from the nucleus, so that would make the galaxy span over 100,000 light years. One of the descriptions must be wrong.
Actually the other article says the 'tails extend 50,000 light years end to end.' I take it the ends are from the tip of the left tail to the tip of the right tail. Another example, would you measure a starfish or a snowflake from one end arm to it nucleus center, or would you measure the starfish from one end to the other?

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by BDanielMayfield » Wed Jan 10, 2018 2:39 pm

heehaw wrote:Sure glad that OUR galaxy is not in a mix-up with another like this one is! Must be very upsetting!
But, just wait for it, wait for it ... The Great Galaxy in Andromeda approaches. :lol2:
"Happy are the peaceable ... "

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by Chris Peterson » Wed Jan 10, 2018 2:59 pm

BDanielMayfield wrote:
heehaw wrote:Sure glad that OUR galaxy is not in a mix-up with another like this one is! Must be very upsetting!
But, just wait for it, wait for it ... The Great Galaxy in Andromeda approaches. :lol2:
I've already added it to my calendar.
Chris

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by neufer » Wed Jan 10, 2018 3:55 pm

Click to play embedded YouTube video.
Chris Peterson wrote:
BDanielMayfield wrote:
heehaw wrote:
Sure glad that OUR galaxy is not in a mix-up with another like this one is! Must be very upsetting!
But, just wait for it, wait for it ... The Great Galaxy in Andromeda approaches. :lol2:
I've already added it to my calendar.
Art Neuendorffer

Guest

Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by Guest » Wed Jan 10, 2018 4:20 pm

Chris Peterson wrote:
BDanielMayfield wrote:
heehaw wrote:Sure glad that OUR galaxy is not in a mix-up with another like this one is! Must be very upsetting!
But, just wait for it, wait for it ... The Great Galaxy in Andromeda approaches. :lol2:
I've already added it to my calendar.
What's the message you entered? At which date?

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by Ann » Wed Jan 10, 2018 4:30 pm

This is a fine portrait of a fascinating merging pair of galaxies.

The "merger product" is reasonably blue, in view of all the dust this smash-up generates. The U-B index of this galactic train wreck is 0.110 and its B-V index is 0.660. This makes it (in my opinion) probably bluer than our own galaxy, whose B-V is (I would guess) around 0.80 or even 0.85.

NGC 2623 is indeed very dusty. It it is four magnitudes brighter in infrared light than in blue light, which definitely proves that it contains a lot of dust. Among nearby galaxies, I can only think of M82 as a comparison, since M82 is also four magnitudes brighter in the infrared than in blue light. But M82 is considerably redder than NGC 2623. The U-B of M82 is 0.310 (versus 0.110 for NGC 2623) and its B-V is 0.890 (versus 0.660 for NGC 2623). So we have every reason to believe that NGC 2623 is even more of a starburst galaxy than M82.

Of course, NGC 2623 has received more of a whomp than M82! And like someone pointed out, the Milky Way's time is coming. But not while we are around!

Ann
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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by Chris Peterson » Wed Jan 10, 2018 4:49 pm

Guest wrote:
Chris Peterson wrote:
BDanielMayfield wrote: But, just wait for it, wait for it ... The Great Galaxy in Andromeda approaches. :lol2:
I've already added it to my calendar.
What's the message you entered? At which date?
Don't need to worry about that anymore. You can just say "Alexa, warn me 10 minutes before Andromeda collides with the Milky Way".
Chris

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by neufer » Wed Jan 10, 2018 5:46 pm

Chris Peterson wrote:
You can just say "Alexa, warn me 10 minutes before Andromeda collides with the Milky Way".
I should think that by then we would have the technology to
divert Andromeda away from a direct collision (; or else blow it up).
Art Neuendorffer

khh

Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by khh » Wed Jan 10, 2018 11:12 pm

What would be the effects on Earth of another galaxy colliding with the Milky Way?

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by neufer » Wed Jan 10, 2018 11:29 pm

khh wrote:
What would be the effects on Earth of another galaxy colliding with the Milky Way?
As long as we have 10 minutes warning we should be OK.
Art Neuendorffer

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by MarkBour » Thu Jan 11, 2018 1:16 am

neufer wrote:
khh wrote:
What would be the effects on Earth of another galaxy colliding with the Milky Way?
As long as we have 10 minutes warning we should be OK.
You aren't worried, but sometimes ...
Click to play embedded YouTube video.
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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by JohnTheWysard » Thu Jan 11, 2018 1:18 am

khh wrote:What would be the effects on Earth of another galaxy colliding with the Milky Way?
Over the few million years that the collision will take, the Milky Way will look different (and probably brighter) from dark skies.

The Galaxy is overwhelmingly empty space. Star-star collisions or even close encounters are very unlikely except in the sparse high-density regions like the cores of globular clusters (or the Galactic Nucleus).

Pretty boring, if you're in it!

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by BDanielMayfield » Thu Jan 11, 2018 3:07 pm

JohnTheWysard wrote:
khh wrote:What would be the effects on Earth of another galaxy colliding with the Milky Way?
Over the few million years that the collision will take, the Milky Way will look different (and probably brighter) from dark skies.

The Galaxy is overwhelmingly empty space. Star-star collisions or even close encounters are very unlikely except in the sparse high-density regions like the cores of globular clusters (or the Galactic Nucleus).

Pretty boring, if you're in it!
It might double the odds of interstellar asteroids passing through our solar system.
"Happy are the peaceable ... "

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Re: APOD: NGC 2623: Merging Galaxies from Hubble (2018 Jan 10)

Post by Chris Peterson » Thu Jan 11, 2018 3:31 pm

khh wrote:What would be the effects on Earth of another galaxy colliding with the Milky Way?
Most likely very little. But it does depend on the how the local stellar density changes. If a dense, central part of Andromeda intersected Earth's region of the Milky Way, such that you had many stars within a light year or less of each other, gravitational perturbations would throw lots of Oort cloud bodies into the inner solar system, and our planets could be shifted to different orbits or even ejected from the Solar System.

That said, however, by the time this happens Earth will no longer be habitable.
Chris

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The Andromeda–Milky Way-Triangulum threesome

Post by neufer » Thu Jan 11, 2018 3:49 pm

https://en.wikipedia.org/wiki/Andromeda%E2%80%93Milky_Way_collision wrote:
<<The Andromeda–Milky Way collision is a galactic collision predicted to occur in about 4 billion years between the two largest galaxies in the Local Group—the Milky Way (which contains the Solar System and Earth) and the Andromeda Galaxy. The stars involved are sufficiently far apart that it is improbable that any of them will individually collide. Some stars will be ejected from the resulting galaxy, nicknamed Milkomeda or Milkdromeda.

Until 2012, it was not known whether the possible collision was definitely going to happen or not. In 2012, researchers concluded that the collision is sure using Hubble to track the motion of stars in Andromeda between 2002 and 2010 with sub-pixel accuracy. Andromeda's tangential or sideways velocity with respect to the Milky Way was found to be much smaller than the speed of approach and therefore it is expected that it will directly collide with the Milky Way in around four billion years. The studies also suggest that M33, the Triangulum Galaxy—the third-largest and third-brightest galaxy of the Local Group—will participate in the collision event too. Its most likely fate is to end up orbiting the merger remnant of the Milky Way and Andromeda galaxies and finally to merge with it in an even more distant future. However, a [M33] collision with the Milky Way, before it collides with the Andromeda Galaxy, or an ejection from the Local Group cannot be ruled out.

The Milky Way and Andromeda galaxies each contain a central supermassive black hole (SMBH), these being Sagittarius A* (ca. 3.6×106 M) and an object within the P2 concentration of Andromeda's nucleus (1–2×108 M). These black holes will converge near the center of the newly formed galaxy over a period that may take millions of years, due to a process known as dynamical friction: As the SMBHs move relative to the surrounding cloud of much less massive stars, gravitational interactions lead to a net transfer of orbital energy from the SMBHs to the stars, causing the stars to be "slingshotted" into higher-radius orbits, and the SMBHs to "sink toward the galactic core." When the SMBHs come within one light-year of one another, they will begin to strongly emit gravitational waves that will radiate further orbital energy until they merge completely. Gas taken up by the combined black hole could create a luminous quasar or an active galactic nucleus, releasing as much energy as 100 million supernova explosions. As of 2006, simulations indicated that the Sun might be brought near the center of the combined galaxy, potentially coming near one of the black holes before being ejected entirely out of the galaxy. Alternatively, the Sun might approach one of the black holes a bit closer and be torn apart by its gravity. Parts of the former Sun would be pulled into the black hole.

Two scientists with the Harvard–Smithsonian Center for Astrophysics stated that when, and even whether, the two galaxies collide will depend on Andromeda's transverse velocity. Based on current calculations they predict a 50% chance that in a merged galaxy, the Solar System will be swept out three times farther from the galactic core than its current distance. They also predict a 12% chance that the Solar System will be ejected from the new galaxy sometime during the collision. Such an event would have no adverse effect on the system and the chances of any sort of disturbance to the Sun or planets themselves may be remote.


Excluding planetary engineering, by the time the two galaxies collide the surface of the Earth will have already become far too hot for liquid water to exist, ending all terrestrial life; that is currently estimated to occur in about 3.75 billion years due to gradually increasing luminosity of the Sun (it will have risen by 35–40% above the current luminosity).

When two spiral galaxies collide, the hydrogen present on their disks is compressed producing strong star formation as can be seen on interacting systems like the Antennae Galaxies. In the case of the Andromeda–Milky Way collision, it is believed that there will be little gas remaining in the disks of both galaxies, so the mentioned starburst will be relatively weak, though it still may be enough to form a quasar.

The galaxy product of the collision has been nicknamed Milkomeda or Milkdromeda. According to simulations, this object will look like a giant elliptical galaxy, but with a center showing less stellar density than current elliptical galaxies. It is, however, possible the resulting object will be a large disk galaxy, depending on the amount of remaining gas in the Milky Way and Andromeda.>>
Art Neuendorffer