Wanted for Reckless Drving at Warp Speed

Reports are coming in that the Andromeda Galaxy, aka M31 aka NGC 224, was seen leaving the scene of an accident & is wanted for questioning. Investigators report finding a trail of stars & debris left near the scene of the crash. Witnesses report that it was seen heading towards the Milky Way Galaxy & was expected to arrive there in a few billion years. Residents are warned to keep out an eye for Andromeda & report any sightings to authorities. Andromedia is often seen with his associate known only as M32 aka NGC 221. They are unsure if M31 is armed but urge caution to not try & stop the renegade galaxy by yourself. According to authorities several witnesses including the Triangulum Galaxy (M33, NGC 598), the Pisces Dwarf (LGS 3, PGC3792) & M110 who sometimes goes by the name of NGC 205 identified Andromedia as the culprit.

Sounds like a great story line used in the film noir genre. Or something from a tabloid newspaper. Definitely not scientific fact. Actually, even though I played it up to sound like that, scientists have recently reported discovering evidence that the Andromeda Galaxy has at some time in its ancient past collided with another galaxy. This crash is supposed to have helped give Andromeda its current shape.

According to a report on Space.com: "Astronomers using the DEIMOS spectrograph on the Keck II Telescope in Hawaii determined this by surveying Andromeda, our galaxy's nearest large galactic neighbor, and discovered a trail of stars which they believe were part of a different galaxy that merged with Andromeda some 700 million years ago.

The findings support previous computer simulations of a dwarf galaxy merging with Andromedaand could help astronomers calculate Andromeda’s total mass, a slippery value that, once arrived at, could help shed light on the elusive dark matter that pervades the universe."

These findings were presented by Karoline Gilbert, a graduate student at the University of California, Santa Cruz at the American Astronomical Society meeting in Seattle earlierin January of this year.

"The discovered tidal debris features are almost an exact match with the features predicted in the computer simulations, Gilbert said. This implies that this new stellar stream and the giant southern stream, as well as the other stellar features reproduced in the simulations, came from the same parent galaxy.

Because they are moving together, astronomers can use the stars in the tidal debris to measure the strength of gravity around the Andromeda galaxy, said Mark Fardal of the University of Massachusetts Amherst who created the computer models.

Gilbert’s discovery of a new tidal debris feature, combined with velocity measurements of the other related tidal debris, will provide observations necessary to measure how much dark matter is in Andromeda, he said, and how it is distributed."

Though the Andromeda Galaxy is about 2.2-2.5 million light-years from the Milky Way Galaxy (our home), it IS heading this way. (1 light-year is about 6 trillion miles, or 10 trillion kilometers) It is travelling this way at about 310,000 miles per hour (500,000 kph). ETA is about 3 billion years from now. So even that part of the opening is based on fact. Even though that event is so far off, scientists are already doing computer simulations to guess what will happen when they do collide.

The good news, on its 1st pass Andromeda may not actually collide with our galaxy, but eventually the 2 galaxies will merge. According to a Space.com e-mail interview with John Dubinksi, an astronomy professor at University of Toronto who has developed a model: "While a collision appears inevitable, astronomers admit that the sideways motion of Andromeda -- the galaxy’s speed perpendicular to its forward path toward the Milky Way -- could affect the encounter’s timing, but it has yet to be measured precisely. Dubinksi used an estimate of 12.4 miles per second (20 km per second) for his collision model.

'Even if the galaxies have a wider passage on the first pass, if they are on a bound orbit they are destined to merge eventually,' Dubinski said. "If not on the first flyby, then within the second or third pass over the next 10 billion years, he added.

The clincher is gravity. Even if there’s enough space between the Milky Way and Andromeda to simply brush past each other at spiral arm’s length, their mutual gravity will ultimately win out, drawing the two galaxies together on successive flybys.' " So, it looks like we aren't off the hook.

& just so you don't think my openning bit was way out there (pun intended) here is a quote from that same article from Joshua Barnes of the University of Hawaii who has done some work investigating another galactic crash: "Simulating colliding galaxies is a bit like investigating a car crash," Barnes says. "Suppose you had no witnesses, just a couple of wrecked cars. You might try different test crashes, varying things like speed and angle of impact, until you found a way to get the same damage as the original collision. That's basically what we did."

Stay tuned for further reports! Film at 11 (10 pm Central)!

Original articles:

Andromeda Involved In Ancient Galactic Collision

Crash Course: Simulating the Fate of Our Milky Way