Starship Asterisk*

Galaxy NGC 7714 After Collision

Explanation: Is this galaxy jumping through a giant ring of stars? Probably not. Although the precise dynamics behind the featured image is yet unclear, what is clear is that the pictured galaxy, NGC 7714, has been stretched and distorted by a recent collision with a neighboring galaxy. This smaller neighbor, NGC 7715, situated off to the left of the featured frame, is thought to have charged right through NGC 7714. Observations indicate that the golden ring pictured is composed of millions of older Sun-like stars that are likely co-moving with the interior bluer stars. In contrast, the bright center of NGC 7714 appears to be undergoing a burst of new star formation. NGC 7714 is located about 100 million light years away toward the constellation of the Fish (Pisces). The interactions between these galaxies likely started about 150 million years ago and should continue for several hundred million years more, after which a single central galaxy may result.

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Awesome!!!

Turn it 90degs or counter clockwise, put it off the coast of Haiti, and it looks like a Hurricane...

What would happen to Earth in such a melee? Probably no collision, but knocked around?

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So...um...two...hypothetical space-fairing species....with decent "empires"....take notice of each other....it is going to be a long time passing...and some stars are captured.... how do the species interact????

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Great picture! Galaxies are my favorite objects in astronomy, and peculiar and interacting galaxies are even better. Thanks for that link to the APOD Restrospective about peculiar and interacting galaxies, too!

Ann

By the way, I found this link that tells you about the size of NGC 7714 (it's small) and the filters used for the image. The blue color represents ultraviolet light, so those blue stars are hot stuff!

Ann

Ann wrote:By the way, I found this link that tells you about the size of NGC 7714 (it's small) and the filters used for the image. The blue color represents ultraviolet light, so those blue stars are hot stuff!

Ann

I always love Hubble images of peculiar galaxies but generally any images of interacting and colliding galaxies, they always covey a sense of dynamism and titanic forces. This image is missing Ha which also would have showed many emission nebulae, the birth of some would have likely been triggered by the collision.

Ann wrote:By the way, I found this link that tells you about the size of NGC 7714 (it's small) and the filters used for the image. The blue color represents ultraviolet light, so those blue stars are hot stuff!

Ann

Yes, 2000 light years is oddly small. I am having some doubt whether that is correct.
For comparison, the Large Magellanic Cloud is 14000 light years in diameter and our Milky Way is estimated as 100k-180k light years.
And this site http://rebuild-the-universe.wikia.com/wiki/NGC_7714 suggest a 35000 light year diameter.
And this one http://cseligman.com/text/atlas/ngc77.htm#7714 mentions 70000 light years.
So, a lot of wildly different numbers.

Craine wrote:

Ann wrote:By the way, I found this link that tells you about the size of NGC 7714 (it's small) and the filters used for the image. The blue color represents ultraviolet light, so those blue stars are hot stuff!

Ann

Yes, 2000 light years is oddly small. I am having some doubt whether that is correct.

Yes, but consider this:

APOD Robot wrote:
Observations indicate that the golden ring pictured is composed of millions of older Sun-like stars

Millions of older Sun-like stars? That's a tiny number indeed. The Milky Way likely contains 200 billion stars, most of which are Sun-like or even smaller and cooler. A galaxy that contains only millions of Sun-like stars has to be either small or extremely star-poor, so that its surface brightness is extremely low. The latter condition does not apply to NGC 7741.

Ann

Craine wrote:Yes, 2000 light years is oddly small. I am having some doubt whether that is correct.

Your doubt is justified.

The nominal distance to the galaxy found in recent literature is 14 Mpc (46 Mly). It subtends about 4 arcminutes. So its physical diameter is around 50,000 ly, which is consistent with what we'd expect for a galaxy like this.

Chris Peterson wrote:

Craine wrote:

Ann wrote:
By the way, I found this link that tells you about the size of NGC 7714 (it's small).

Yes, 2000 light years is oddly small. I am having some doubt whether that is correct.

Your doubt is justified. The nominal distance to the galaxy found in recent literature is 14 Mpc (46 Mly). It subtends about 4 arcminutes. So its physical diameter is around 50,000 ly, which is consistent with what we'd expect for a galaxy like this.

First off... Ann's link states that the actual small size of NGC 7714 is ~6.5 Kpc which should have read 20,000 light years consistent with being at a distance of 14 Mpc (46 Mly).

Chris's 4 arcminutes (~50,000 ly) refers more to the pair of interacting galaxies NGC 7714 + NGC 7715 (a.k.a., Arp 284).

(Note, however, that the redshift distance to Arp 284 is more like 141 Mly and would make everything not quite so small.)

neufer wrote:...
Chris's 4 arcminutes (~50,000 ly) refers more to the pair of interacting galaxies NGC 7714 + NGC 7715 (a.k.a., Arp 284).

(Note, however, that the redshift distance to Arp 284 is more like 141 Mly and would make everything not quite so small.)

SIMBAD quotes the distance as ~39.6 Mpc, which would be around 130Mly.
NASA/IPAC quotes 30 Mpc or about 100Mly.
SpaceTelescope quotes 100 Mly. (probably taken from NASA/IPAC)

It may be due to some different red-shift numbers from different observations.

Bottom line: It's a cool photo!

A lot of people don't like to hear talk about how humans are "but moments of light, fading in the grass" (as the Youngbloods put it), but reading this caption and looking at a picture of colliding galaxies, IMHO, puts me in a perspective that does not constitute an insult or condescending put-down. I feel lucky to live in an age where instruments and astrophysics gives us all a clue to images like this. I don't feel small ; I feel calibrated.

chuckster wrote:I don't feel small ; I feel calibrated.

That's a pretty good way of putting it.

geckzilla wrote:

chuckster wrote:I don't feel small ; I feel calibrated.

That's a pretty good way of putting it.

I agree. But I feel more than calibrated. I feel pretty awesome. It took the universe to make me and the rest of humanity. Isn't that something?

Ann

Ann wrote:I agree. But I feel more than calibrated. I feel pretty awesome. It took the universe to make me and the rest of humanity. Isn't that something?

I don't know if it is or is not. Say our Universe is the experiment of something else's advanced equivalent of elementary school children. Who's to say ours is the smart student's and not their version of Ralph Wiggum?

geckzilla wrote:

Ann wrote:I agree. But I feel more than calibrated. I feel pretty awesome. It took the universe to make me and the rest of humanity. Isn't that something?

I don't know if it is or is not. Say our Universe is the experiment of something else's advanced equivalent of elementary school children. Who's to say ours is the smart student's and not their version of Ralph Wiggum?

Our Universe might be the experiment of something else's advanced equivalent of elementary school children? Well, when I was a teen a bunch of us used to say that the Universe might be a molecule in a tire in somebody else's super-duper-mega-kiloparsecs-are-nothing bicycle. We wondered where this super-duper-mega-kiloparsecs-are-nothing person was pedalling us, and what would happen if we hit a sharp super-duper-mega-kiloparsecs-are-nothing rock, so that our Universe split open and the super-duper-mega-kiloparsecs-are-nothing bicycle tire got a puncture.

But hey, I'm quite satisfied to think of our Universe as perfectly impersonal and without purpose. And I love thinking that this senseless thing exploded from the Big Bang and evolved and convulsed and produced stars and supernovas and tossed around dark matter and dark energy until eventually, after almost fourteen billion years, it made us. Pretty neat!

Ann

Still, with no other examples with to compare ourselves to, it's hard to say if it's the neatest Universe or not. I mean, we might be a plain black marble while others are chock full of blue stuff instead of mostly empty void. What would you think about a Universe that's got lots of blue stuff in it?

geckzilla wrote:Still, with no other examples with to compare ourselves to, it's hard to say if it's the neatest Universe or not. I mean, we might be a plain black marble while others are chock full of blue stuff instead of mostly empty void. What would you think about a Universe that's got lots of blue stuff in it?

It's like those people who had to come up with the idea of a paradise in the afterlife because this Earth isn't good enough. Sure, a blue Universe would be nice, but I'll be careful with what I wish for. I think that a contracting Universe on its way the the Big Crunch would be blue (because everything in it would be blueshifted), but that doesn't mean I would want that thing!

Ann

It could be one where there isn't any crunching or expanding. Maybe it doesn't even have gravity or maybe gravity works way differently.

For all intents and purposes, the universes of our imaginations are more real than any universes beyond our observable universe. Some of the universes in my head are much groovier than the observable universe. Some are bleaker.

Clicking on the APOD brings up the full image that was also in the Hubble NewsCenter and Hubble ESA releases. For my interest (and anyone else that may have wondered) does anyone know the name (if it has one ) of the obvious galaxy in the right in the full image.

DavidLeodis wrote:Clicking on the APOD brings up the full image that was also in the Hubble NewsCenter and Hubble ESA releases. For my interest (and anyone else that may have wondered) does anyone know the name (if it has one ) of the obvious galaxy in the right in the full image.

It doesn't have a name. It has at least a couple of catalog entries but that's it. NED search

geckzilla wrote:

DavidLeodis wrote:Clicking on the APOD brings up the full image that was also in the Hubble NewsCenter and Hubble ESA releases. For my interest (and anyone else that may have wondered) does anyone know the name (if it has one ) of the obvious galaxy in the right in the full image.

It doesn't have a name. It has at least a couple of catalog entries but that's it. NED search

Thanks geckzilla . So it's a GWAN (Galaxy Without A Name). I think I may claim it to be named David's Galaxy .

The other galaxy in the upper right, near the red star, looks like the alien mothership from Independence Day...perhaps that is where they hail from