Starship Asterisk*

Merging NGC 2623

Explanation: NGC 2623 is really two galaxies that are becoming one. Seen to be in the final stages of a titanic galaxy merger, the pair lies some 300 million light-years distant toward the constellation Cancer. The violent encounter between two galaxies that may have been similar to the Milky Way has produced widespread star formation near a luminous core and along eye-catching tidal tails. Filled with dust, gas, and young blue star clusters, the opposing tidal tails extend well over 50,000 light-years from the merged nucleus. Likely triggered by the merger, accretion by a supermassive black hole drives activity within the nuclear region. The star formation and its active galactic nucleus make NGC 2623 bright across the spectrum. This sharp cosmic snapshot of NGC 2623 (aka Arp 243) is based on Hubble Legacy Archive image data that also reveals even more distant background galaxies scattered through the field of view.

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Is there any information about the filters that were used to produce this image? I checked the links in today's caption, but I couldn't finad any information about the particulars relating to today's image. The first link doesn't seem to work, at least not when I clicked on it.

Ann

Editors already notified about the broken first link. FWIW it does work in the bot's post. Filter info is there.

Looks like a propeller...

Next on Dragonball Z.... Galactic Fusion....

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Boomer12k wrote: Next on Dragonball Z.... Galactic Fusion....

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What hubble has managed to catch in this image is not a galaxy merger, but the coalescence of a spirit bomb.

Two galaxies joined to dance ♥

What is the round red galaxy to which the arrow at the bottom is pointing?

I'm curious about hte two stars in the lower right corner of the snapshot. Are they close enough together to be a binary system or are they just located very close to line of sight but far enough from one another that they're not orbiting a common center of gravity. I think it's interesting that they appear to be about the same size and color as one another. Perhaps they were born of the same nebula at about the same time?

Thank you APOD for another beautiful and thought provoking image today!

http://www.spacetelescope.org/videos/heic0912a/ mentions the use of Hubble visible, Chandra x-ray, Spitzer infra-red, GALEX ultra-violet, and ESA's multi-mirror x-ray telescopes to study NGC 2623, but the image d'jure is only Hubble's Advanced Camera for Surveys with the filters that Master Digitator mentioned.

946842 wrote:I'm curious about hte two stars in the lower right corner of the snapshot. Are they close enough together to be a binary system or are they just located very close to line of sight but far enough from one another that they're not orbiting a common center of gravity. I think it's interesting that they appear to be about the same size and color as one another. Perhaps they were born of the same nebula at about the same time?

The stars are almost certainly a binary pair. They belong to our Milky Way, so they are not all that distant. It's a faint pair of stars, however. My software detects them, but has no information about them. They are likely of 15th or 16th magnitude.

What kind of stars are they? I find it unlikely that they are a pair of evolved stars, a pair of red giants. Such stars exist but are not common. An interesting almost-example might be bright and well-known star Capella, which consists of two yellow giants. But like I said, this isn't common.

Instead, we might be talking about, say, a binary pair of main sequence K-type stars. Such stars are cooler and fainter than the Sun. The pair in today's APOD could be similar to 61 Cygni, a pair of K-type stars which were the first ever stars to have their parallax measured.

We should note that this image was assembled from exposures through two filters, a blue one and an infrared one. The fact that the stars are bright in the infrared but faint in the blue filter suggests that they likely belong to spectral class K or M. They are probably a binary pair of red dwarfs.

Ann

APOD Robot wrote: Merging NGC 2623

Explanation: NGC 2623 is really two galaxies that are becoming one.

• Seen to be in the final stages of a titanic galaxy merger,

• Titanic galaxy merger .... I can cover it with my thumb

This is a new object for me - one that's definitely slipped through my observing list net! But I shall make amends on Saturday and image it live for anyone to see.....

To celebrate Astronomy Day, I'll be broadcasting an 11hr marathon of live astronomy on Saturday (starting at 12:30PM PDT and ending at 11:30PM PDT).

I've already scheduled the robotic telescopes in the Canary Islands to generate live color images of comets, asteroids, the planet Jupiter and its moons, galaxies, nebulae, supernovae remnants, and just about every other type of celestial object, but I shall now add NGC 2623 to the list! It'll be interesting to see how well the Half Metre telescope at the Canary Islands Observatory will image this particular galaxy.

There seems to be very little written about this second Astronomy Day of 2012, which is a great pity as we need to take every opportunity to engage a wider audience to astronomy and science. It's always a fun day which lives up to its tagline "Bringing astronomy to the people".

Everyone is welcome to the free public shows tomorrow - there's more info here: http://goo.gl/8vhi6

I can be contacted at coxy@slooh.com (I'm taking requests for objects to target in the last couple of hours of the event).

I have my own views if how galaxies merge, and so I have a different interpretation on this altogether. I do agree this this is a galaxy merger, and that the two original galaxies are stretched out in this image, with their cores merging in the center. However, when I see pictures of galaxies merging, I see early on a bridge develop between the galaxies that the simulations do not recreate. When this bridge becomes dominant, it seems to become the bar in a barred spiral galaxy with the remains of the original galaxies being the arms of the barred spiral. If the merging galaxies were spirals, then their arms become secondary arms in the merged galaxy. I also believe that as the merged galaxy ages. it wraps itself tighter and tighter until (if left undisturbed) it becomes a grand spiral with a tight core and well wrapped spiral arms.

So what do I think that we are seeing here? I think that this is a merger at the stage where it is a loose barred spiral, and that we are looking straight down the bar. The merger appears to be between a larger galaxy and a smaller one. The remains of the larger galaxy mostly are to the left of the central core/bar in this image, but if you look at the lower right of the center, you see a blue blob that is similar in color to the "arm" on the left. That is the start of that arm. It wraps around behind the core and then appears again at the upper left of the core and heads on out.

The remains of the smaller galaxy start behind the core/bar from our point of view. That arm comes out on the left side of the core/bar, goes in front of it, and then curves around and heads back behind the core/bar again. A branch does head off to the right, and I assume that this is a tidal tail.

In addition, orange tendrils of gas and dust can be seen being pulled off of the nearer sections of the original-galaxies/arms and into the still forming core of the new galaxy.

So that is my alternate view of things. My overall opinion is that galaxy mergers are not well understood at all, and that there is much to learn about galaxies and the dark matter. Especially troubling to me is that the simulations that I see of mergers all fail to reproduce the bridge that I see between the interacting galaxies such as the Antenna galaxies. I repeat that the only reason that a bridge is not visible here is that we are looking straight down it. So this is an alternate and possibly very enlightening image of a loose barred spiral galaxy IMO.

Edward Schaefer

I am trying to figure out if the very faint smudges close are globular clusters.

MartyBob wrote:I am trying to figure out if the very faint smudges close are globular clusters.

There are a number of very faint smudges which are seen against the blackness of space. These aren't globular clusters, but low-surface brightness distant galaxies.

However, there are some round bright "stars" seen inside the galaxy itself. These aren't normal stars, but bright clusters. Some of them are so bright that they might survive over billions of years as globular clusters.

Ann

Ann wrote:

946842 wrote:I'm curious about hte two stars in the lower right corner of the snapshot. Are they close enough together to be a binary system or are they just located very close to line of sight but far enough from one another that they're not orbiting a common center of gravity. I think it's interesting that they appear to be about the same size and color as one another. Perhaps they were born of the same nebula at about the same time?

The stars are almost certainly a binary pair. They belong to our Milky Way, so they are not all that distant. It's a faint pair of stars, however. My software detects them, but has no information about them. They are likely of 15th or 16th magnitude.

What kind of stars are they? I find it unlikely that they are a pair of evolved stars, a pair of red giants. Such stars exist but are not common. An interesting almost-example might be bright and well-known star Capella, which consists of two yellow giants. But like I said, this isn't common.

Instead, we might be talking about, say, a binary pair of main sequence K-type stars. Such stars are cooler and fainter than the Sun. The pair in today's APOD could be similar to 61 Cygni, a pair of K-type stars which were the first ever stars to have their parallax measured.

We should note that this image was assembled from exposures through two filters, a blue one and an infrared one. The fact that the stars are bright in the infrared but faint in the blue filter suggests that they likely belong to spectral class K or M. They are probably a binary pair of red dwarfs.

Ann

Thanks Ann. How interesting... stars and galaxies doing the cosmic dance!

neufer wrote:

[url=http://burro.cwru.edu/JavaLab/GalCrashWeb/]Titanic galaxy merger[/url] :?:

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APOD Robot wrote: Merging NGC 2623

Explanation: NGC 2623 is really two galaxies that are becoming one.

• Seen to be in the final stages of a titanic galaxy merger,

• Titanic galaxy merger .... I can cover it with my thumb

You seem to have covered it with a thumbnail.

946842 wrote:
How interesting... stars and galaxies doing the cosmic dance!

http://asterisk.apod.com/viewtopic.php? ... 13#p185963