APOD: Cartwheel of Fortune (2018 Jan 25)

[APOD Robot]

Cartwheel of Fortune

Explanation: By chance, a collision of two galaxies has created a surprisingly recognizable shape on a cosmic scale, The Cartwheel Galaxy. The Cartwheel is part of a group of galaxies about 500 million light years away in the constellation Sculptor. Two smaller galaxies in the group are visible on the left. The Cartwheel Galaxy's rim is an immense ring-like structure 150,000 light years in diameter composed of newly formed, extremely bright, massive stars. When galaxies collide they pass through each other, their individual stars rarely coming into contact. Still, the galaxies' gravitational fields are seriously distorted by the collision. In fact, the ring-like shape is the result of the gravitational disruption caused by a small intruder galaxy passing through a large one, compressing the interstellar gas and dust and causing a star formation wave to move out from the impact point like a ripple across the surface of a pond. In this case the large galaxy may have originally been a spiral, not unlike our own Milky Way, transformed into the wheel shape by the collision. But ... what happened to the small intruder galaxy?

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[RocketRon]

Two smaller galaxies in the group are visible on the right.

Visible on our left, perhaps ?

Oh to have had a timelapse camera operating over the past few million years.
Great image, just the same....

[sillyworm2]

All this time I thought it was the small irregular(?) galaxy that had been involved in the collision.

[Ann]

All this time I thought it was the small irregular(?) galaxy that had been involved in the collision.

No, because a small galaxy like that would lose most of its gas crashing through a big galaxy.

The small blue galaxy has too much gas and star formation to have ripped right through the bigger galaxy. And the small yellow galaxy is too regular to have ripped right through the bigger galaxy.

Ann

[JohnD]

Ann, follow the link in the last words of the APOD, to see a previous POD that traces wher the intruderr might be.

Isn't it strange? The cartwheel appears to have two neighbours, one that looks just like its hub, and another that looks just like the wheel and rim! If the Sun was somewhere else, with a different line of sight, we might see the cartwheel in a different position or else four galaxies, a pair od hubs and a pair of wheels!

John

[Ann]

Ann, follow the link in the last words of the APOD, to see a previous POD that traces wher the intruderr might be.

Isn't it strange? The cartwheel appears to have two neighbours, one that looks just like its hub, and another that looks just like the wheel and rim! If the Sun was somewhere else, with a different line of sight, we might see the cartwheel in a different position or else four galaxies, a pair od hubs and a pair of wheels!

John

I did look at the real intruder! Interesting, isn't it? The real intruder doesn't have too much gas, and it isn't too regular.

But the small pair of galaxies next to the big ones is funny. The two little ones are so similar in size and so different in shape and color. Like you said, one looks like a hub and the other like a wheel and rim!

Ann

[De58te]

What happened to the intruder galaxy? I'm guessing it is the smaller galaxy on the left with all those blue newly formed stars surrounding it. And Ann how do you know the small galaxy wasn't double or 4 times the size it is now before it collided with the cartwheel?

[neufer]

Click to play embedded YouTube video.

Doing cartwheels to celebrate the end of an era

<<Astronomer Bob Fosbury, who is stepping down as Head of the ST-ECF, was responsible for much of the early research into the Cartwheel Galaxy — including giving the object its very apposite name — and so this image was selected as a fitting tribute. The object was first spotted on wide-field images from the UK Schmidt telescope and then studied in detail using the Anglo-Australian Telescope.>>

[grogersrn]

The reason for the text describing the two smaller galaxies as being on the right when they are shown on the left is that the entire text of the caption was lifted from the February 23, 1997 APOD, where the image is reversed from this one. They even copied the typo of having the article "a" duplicated in the second to last sentence ("causing a a star formation wave to move out").

[moconnor]

The last link, which takes you to an APOD from 1997, shows the intruder galaxy, which they indicate as being 250,000 light years away from the Cartwheel Galaxy! That makes me wonder when the galaxy collision took place. How long does it take for the two galaxies to be that far apart?

[Case]

Two smaller galaxies in the group are visible on the right.

Visible on our left, perhaps ?

That line seems to be copied from the APOD for December 19, 1998, which has a different orientation.

[Fred the Cat]

Dark matter, dark energy and now dark plasma. Anyone have an explanation what this new term (to me) represents in the invisible universe? A knowledge transfusion would surely boost my grey matter and stimulate more fluid-like behaviors.

[bystander]

Dark matter, dark energy and now dark plasma. Anyone have an explanation what this new term (to me) represents in the invisible universe? A knowledge transfusion would surely boost my grey matter and stimulate more fluid-like behaviors.

What does this have to do with today's post?

[JohnD]

Dark matter, dark energy and now dark plasma. Anyone have an explanation what this new term (to me) represents in the invisible universe? A knowledge transfusion would surely boost my grey matter and stimulate more fluid-like behaviors.

What does this have to do with today's post?

The link is to a paper entitled "Simulations of galaxy cluster collisions with a dark plasma component".
My underline

And the paper does explain what it's talking about, "Dark plasma is an intriguing form of self-interacting dark matter with an effective fluid-like behavior, which is well motivated by various theoretical particle physics models" Help you, Fred? No, nor me, really!
John

[neufer]

The last link, which takes you to an APOD from 1997, shows the intruder galaxy, which they indicate as being 250,000 light years away from the Cartwheel Galaxy! That makes me wonder when the galaxy collision took place. How long does it take for the two galaxies to be that far apart?

The Andromeda Galaxy is 2,500,000 light years away from
the Milky Way with which it will collide in ~4.5 billion years.

• So maybe about 450 million years?

[Wha?]

When galaxies collide

I can't get the Galaxy Crash applet to work. Is it just me?

[neufer]

Credit: Composite: NASA/JPL/Caltech/P.Appleton et al. X-ray: NASA/CXC/A.Wolter & G.Trinchieri et al.

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Chandra 2007: Astronomers Do Flips Over Cartwheel Galaxy

<<This image combines data from four different observatories: the Chandra X-ray Observatory (purple); the Galaxy Evolution Explorer satellite (ultraviolet/blue); the Hubble Space Telescope (visible/green); the Spitzer Space Telescope (infrared/red). The unusual shape of the Cartwheel Galaxy is likely due to a due to a collision with one of the smaller galaxies on the lower left several hundred million years ago. The smaller galaxy produced compression waves in the gas of the Cartwheel as it plunged through it. These compression waves trigger bursts of star formation. The most recent star burst has lit up the Cartwheel's rim, which has a diameter larger than that of the Milky Way galaxy, with millions of bright young stars. The brightest X-ray sources are likely black holes with companion stars, and appear as the white dots that lie along the rim of the X-ray image. The Cartwheel contains an exceptionally large number of these black hole binary X-ray sources, because many massive stars formed in the rim.>>

The neutral hydrogen trail suggestively leads to the culprit galaxy at the far right, presently about 250,000 light years distant from the Cartwheel!

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Astronomy Picture of the Day : February 24, 1997

Explanation: In yesterday's episode our hero, the Cartwheel galaxy, had survived a chance cosmic collision with a small intruder galaxy - triggering an expanding ring of star formation. Hot on the intruder's trail, a team of multiwavelength sleuths have compiled evidence tracking the reckless galaxy fleeing the scene. Presented for your consideration: a composite showing a visual image of the Cartwheel galaxy and smaller galaxies of the Cartwheel group, superposed with high resolution radio observations of neutral hydrogen (traced by the green contours). The neutral hydrogen trail suggestively leads to the culprit galaxy at the far right, presently about 250,000 light years distant from the Cartwheel!>>

[JohnD]

When galaxies collide

I can't get the Galaxy Crash applet to work. Is it just me?

Works for me, but it's a pretty MickeyMouse simulation. This one is better, complete with superimposed pictures from Hubble of real galaxies that sjow the various stages of interaction: https://www.youtube.com/watch?v=lXy3B2K47Qg

John

[sillyworm2]

Before my initial post I had followed the link to the culprit galaxy. Considering that the Cartwheel Galaxy is showing the results of a collision,I'm glad they included the link,to show the full story.

[Fred the Cat]

Dark matter, dark energy and now dark plasma. Anyone have an explanation what this new term (to me) represents in the invisible universe? A knowledge transfusion would surely boost my grey matter and stimulate more fluid-like behaviors.

What does this have to do with today's post?

Galaxy, cluster collisions. dark matter interactions. Plasma production. It just seemed interesting and I had wanted to know if anyone could explain what dark plasma was, in reference to in the recent paper, as a term I'd like to understand. Nothing sinister.