APOD: Seyfert's Sextet (2013 Dec 10)

[APOD Robot]

Seyfert's Sextet

Explanation: What will survive this battle of the galaxies? Known as Seyfert's Sextet, this intriguing group of galaxies lies in the head portion of the split constellation of the Snake (Serpens). The sextet actually contains only four interacting galaxies, though. Near the center of this Hubble Space Telescope picture, the small face-on spiral galaxy lies in the distant background and appears only by chance aligned with the main group. Also, the prominent condensation on the upper left is likely not a separate galaxy at all, but a tidal tail of stars flung out by the galaxies' gravitational interactions. About 190 million light-years away, the interacting galaxies are tightly packed into a region around 100,000 light-years across, comparable to the size of our own Milky Way galaxy, making this one of the densest known galaxy groups. Bound by gravity, the close-knit group may coalesce into a single large galaxy over the next few billion years.

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[Boomer12k]

What will survive??? A bigger Galaxy....

"Dance of the Galaxies"...

SWEEEEEET!!!!

Oh, the Gravity of the situation....

:---[===] *

[mike studyform]

The ideal image for me to ponder over for hours. I love to try to comprehend the sheer size and distances involved in intergalactic movement.
Unfortunately, what I actually have for today's desktop picture, is a cat in a sink.
The animal pictures which quite often occur are not only poor quality, they're also not as amusing as whoever chooses them thinks they are.

Does this happen to everybody?

[geckzilla]

Ahaha, cat in a sink desktop. I'd take it. You got cat in a sink because it was the first linked-to jpeg on the page. Today's image was a png. I guess the desktop program (not official and written by a fan, btw) doesn't look for pngs.

[mike studyform]

For those who don't see what I'm seeing.

Click on TIGHTLY PACKED in the image description.

Thanks geckzilla, at least I now know why this keeps happening (at least the mechanics if not the mentality),

[Nitpicker]

Well done geckzilla. So, the tightly packed elliptical feline galaxy (which looks in danger of being sucked into a black hole) is part of the local fluff, and everything else is light years away and aeons ago. Got it!

[Ann]

Great picture!!!

Ann

[jase]

Wow, there is so much happening in that celestial scene! Beautiful image!

[owlice]

Congrats, geckzilla!! This is a stunning image!

mike studyform, the cat pics are, indeed, as amusing as whoever chooses them thinks they are. So are the dog pics.

[Nitpicker]

The comparison with the image in the first link:
http://www.noao.edu/image_gallery/html/im0407.html
using the 2.1m KPNO telescope is rather telling.

The HST is only slightly bigger, but what a difference it makes being in orbit above the atmosphere! (I say this with no knowledge of the raw data from the HST. I'm sure the processing makes a huge difference too.)

[Beyond]

It's rather amazing that the color of the Fluffy Cat Nebula is such, that it allows it to almost purrfectly blend into it's surrounding.

[FloridaMike]

Maybe we should have a Fluffy Cat Nebula Of the Day...

[owlice]

That's no nebula... that's the Fluffy Cat spiral galaxy, with tidal tail.

[Ann]

Well done geckzilla. So, the tightly packed elliptical feline galaxy (which looks in danger of being sucked into a black hole) is part of the local fluff, and everything else is light years away and aeons ago. Got it!

And yay to cats!

Ann

[geckzilla]

The comparison with the image in the first link:
http://www.noao.edu/image_gallery/html/im0407.html
using the 2.1m KPNO telescope is rather telling.

The HST is only slightly bigger, but what a difference it makes being in orbit above the atmosphere! (I say this with no knowledge of the raw data from the HST. I'm sure the processing makes a huge difference too.)

Hubble collects beautiful data. It's definitely more about Hubble and less about processing. I think of the processing as the last fraction of a percent of a long history of evolution.

[tomatoherd]

How do they know they're so tightly packed? The lowest galaxy looks behind the other three, to me. Seems their margin of error on single galaxy distances are always relatively large.
Which reminds me: do astronomers ever use the aid of binocular vision? For instance, an image by Hubble taken with earth on one side of the sun, and repeated 6 months later on the far side, would each be 2 AU apart, and might be enough separation to give a 3D effect if the images were then viewed separately in a right and left human eye, like the old stereoscopes. Then astronomical bodies within a certain range could be grouped or ungrouped. Human 3D works on a range of 6 inches to ? 4 miles, and our eyes are only 2 inches apart. 2 inches and 2 AU: since there are roughly 65,000 inches in a mile, a pair of such Hubble images should definitely show binocular effects out to 65,000 AU and more. Someone convert that to light years for me!
If they've never done this before, they ought to. ( For the record, my name is Shannon Grubb.)

[tomatoherd]

Let me summarize what I wrote: if they haven't already, astronomers ought to avail themselves of earth's changing view of the heavens yearly to produce stereoscopic views of the universe within the effective distance range.

[geckzilla]

They use parallax all the time, Shannon. Early astronomers first used it to determine solar system distances and sizes by doing simultaneous observations from two different locations on Earth. For galaxies, however, redshift must be measured.

[tomatoherd]

And yes, I know, 65,000, even 260,000 AU is not that far out. But it might work for nearby nebulae and what-not. Wouldn't work for today's image....

[tomatoherd]

Thanks, geckzilla.
Yeah, I knew they used parallax. But they end up with a distance, not a beautiful image. If you've ever compared a regular photo of everyday things with a stereoscope of the same scene, the resolution seems to increase by orders of magnitude, even though to actual pixels/resolution really hasn't.
So really just wondering if Hubble was ever used in this way: same image 2 AU apart, and then visualized in 3D to the human sight.

[geckzilla]

I think we'd have amateur astrophotographers doing this all over the place if it yielded three dimensional results. As it is, it would probably be a painstaking process to take minute, sub-pixel parallax movements and emphasize them to create dimension. It might work better for solar system objects but they move all over the place. There are some nebulas by Astro Anarchy that are "fantasy" depictions (as Chris put it) which means that it's not using actual data but a guess by the artist. There are a lot of stereoscopic moon, asteroid, and Mars surface pictures out there, though. Another great one is the fly through of the Hubble deep field but that's not stereoscopic.

[tomatoherd]

"if it yielded"?
It would HAVE to yield, for scenes at the proper distance.
Amateurs don't have control of Hubble.
Amateurs' night skies are totally different six months apart. They couldn't do it from earth.
I think the nebulas in Orion would work. The right-most image has to be viewed only in the right eye, left-most (6 months before or after) in left only. How would they know if it produces awesome images or not if they've never done it???

[geckzilla]

But Hubble's field of view is very narrow. If you try to look at the Orion nebula with Hubble you get only a small part. You'd have an easier time even with the different skies from an Earth observatory, I think. Just pick something that is visible during both seasons. Knowing scientists, they probably know exactly what will happen if Hubble were used like that. Either it won't be that dramatic or no one has succeeded in getting a proposal for it approved.

[Chris Peterson]

How do they know they're so tightly packed? The lowest galaxy looks behind the other three, to me. Seems their margin of error on single galaxy distances are always relatively large.

The redshift measurement is sufficient to identify which galaxies are or are not members of a cluster, and clusters, by their nature, are "tightly packed".

Which reminds me: do astronomers ever use the aid of binocular vision? For instance, an image by Hubble taken with earth on one side of the sun, and repeated 6 months later on the far side, would each be 2 AU apart, and might be enough separation to give a 3D effect if the images were then viewed separately in a right and left human eye, like the old stereoscopes.

Nothing of astronomical interest outside our solar system is close enough to allow for a visually stereoscopic image given a baseline of only 2 AU. The nearest star shows an annual parallax of less than one arcsecond. Stars in the Orion Nebula have parallaxes on the order of one milliarcsecond. We're talking about the sort of stereoscopic views of those objects that you get of the Moon using your eyes.

[geckzilla]

If everything weren't moving all around, you could take the same picture a few decades apart and get some kind of stereoscopic view. If we were near the galactic center then we'd be moving faster than the outer edges of the galaxy and then a picture could be taken looking toward the edge of the Milky Way. Hmm. But then there are things moving away and things moving toward so it's not like we're in a train looking at a landscape flowing by.