Star Cluster Ejected From Galaxy At 2,000,000 MPH

William Robinson writes: "According to a new report, a globular cluster of several thousand stars (compressed into a space just a few dozen light-years apart) is being thrown out of galaxy M87. The cluster, named HVGC-1, is traveling at a rate of 2 million miles per hour. The discovery was made by Nelson Caldwell of the Harvard-Smithsonian Center for Astrophysics and his team while studying the space around the supergiant elliptical galaxy M87. Caldwell and colleagues think M87 might have two supermassive black holes at its center. The star cluster wandered too close to the pair, which picked off many of the cluster's outer stars while the inner core remained intact. The black holes then acted like a slingshot, flinging the cluster away at a tremendous speed."

Comments

Velocity

[dtmos]

Two million miles per hour is less than 0.003c, but still quite a clip, even in astronomical terms.

Since they're discussing velocity (vector speed), and not just speed, the headline is correct in saying " -1000 km/s" when the measured value is -1025 km/s, but one can debate whether the abstract is correct in saying "an extraordinary blueshift of -1025 km/s", rather than "an extraordinary blueshift of 1025 km/s", since "blueshift" gives one the sign of the velocity already.

Re:Velocity

[pr0t0]

I wonder if the Earth was in orbit around a star that was part of such a cluster, would we notice the effects of such an ejection? Certainly the night sky would change, but the whole process could take of millions of years. Would we feel any immediate effects from the proximity to the black holes? What would our current state of technology, instrumentation and measurement tell us about our relative place and speed? And what, if any change would there be in our civilization's future. Not being in the galaxy seems isolating, but if the host star remains unchanged perhaps there is no change in our destiny. Or perhaps that by the time we developed interstellar travel we'd be too far from the host galaxy to travel to anything other than the stars in our cluster.

It'd make for a good sci-fi book I think.

Re:Velocity

[Anonymous Coward]

Only on Slashdot is a speed of 2*10^^6 MPH
1) expressed in imperial units
2) called "pedestrian" by some poster
Good stuff.

Re:Velocity

[LeadSongDog]

So that would be 48.5 megaSmoot/semester, based on the conventional 39 hour semester

Re:Velocity

[skastrik]

Frederik Pohl's The World at the End of Time deals with the ejections of solar systems on a grand scale.

If it's not too much to ask

[Arancaytar]

Could we please use real scientific units when talking about science?

How much is this in libraries of congress per fortnight?

Re:If it's not too much to ask

[stewsters]

Remember that 1 lightyear = 1.03461597 × 1014 American football fields.

They didn't pay the rent?

[tekrat]

A cluster of stars were "thrown out" of galaxy M87?... what, they didn't pay the rent? Or is M87 expressing a case of "tough love"?

The real question is; by what force were they ejected from the galaxy? The fastest we've ever been about to propel something is 24,000 mph -- and that's with a lot of gravity assists.... if we could figure out how to get a spacecraft to 2 million mph, trips around our solar system would go a lot faster.....

Re:They didn't pay the rent?

[CanHasDIY]

It was an old, run down section of the galaxy.

So, what are you trying to say? That black holes only live in the galactic ghetto?

Racist.

Re:They didn't pay the rent?

[CreatureComfort]

Nah, at a constant 1 G acceleration you could get to 2 M mph in under 51 hours.

Another Question

[Mapleperson]

Another questions is what happens to the speeding cluster if is was flung out by a bigger galaxy. One would assume the the dark matter that originally present in the cluster would not take the same track. Without the supporting dark matter the radial velocities are too great for the outer stars of the cluster to continue orbiting the system. One would think that there should be trail of stars left behind. Could be a great way to investigate dark matter interaction with galaxies.

Re:Can anyone explain...

[bjorniac]

Well, there are a few things that would have to happen for them to compare clocks, and a key thing you're overlooking in your analysis:

1) For circular motion, the two ships would not have constant velocity in their _own_ reference frames - they're both accelerating towards the center (I'm assuming a flat space-time here for simplicity, but in GR things don't change much). Acceleration causes time dilation too!

2) For the ships to come together, they would have to maneouver. This will require further accelerations. Its during these that the other ship's clock will always appear to be moving faster.

What you've really got here is a reworking of the classical twin paradox - if one twin goes to Alpha Centauri (AC) and back, and the other stays on Earth, from _each_ perspective, the other one moves away then comes back. Yet the one who went to AC and back comes back younger - why? Well, what you're missing is that _at_ AC you have to slow down and then accelerate back towards Earth. This is the missing segment of the space-time picture, as the surfaces of simultaneity change during this acceleration.

I hope that clarifies things a bit.

Towards Us

[Infiniti2000]

The Virgo Cluster galaxy, M87, has ejected an entire star cluster, throwing it toward us at more than two million miles per hour.

I can imagine people getting alarmed at this, but they shouldn't. If it's truly directly towards us (unlikely), and never veers off course (unlikely), it would still take about 18.3 million years to reach us.

Re:12 Parsecs

[stjobe]

Whoosh.

That was the sound of the Millenium Falcon - the only ship to ever do the Kessel Run in under 12 Parsecs - passing over your head.