Starship Asterisk*

bystander wrote:

Fred the Cat wrote: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?

Wha? wrote:

APOD Robot wrote: When galaxies collide

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

http://chandra.harvard.edu/photo/2006/cartwheel/ wrote:

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

---

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.>>

[url=https://apod.nasa.gov/apod/ap970224.html]1997 APOD: The neutral hydrogen trail?[/url] wrote:

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

---

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!>>

APOD Robot wrote: When galaxies collide

moconnor wrote:
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?

• So maybe about 450 million years?

bystander wrote:

Fred the Cat wrote: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?

Fred the Cat wrote: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.

RocketRon wrote:

APOD Robot wrote: Two smaller galaxies in the group are visible on the right.

Visible on our left, perhaps ?

http://spacetelescope.org/images/potw1036a/ wrote:
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.>>

JohnD wrote: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

sillyworm2 wrote:All this time I thought it was the small irregular(?) galaxy that had been involved in the collision.

APOD Robot wrote: Two smaller galaxies in the group are visible on the right.