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## Star Cluster Ejected From Galaxy At 2,000,000 MPH133

Posted by Soulskill
from the get-out-and-stay-out dept.
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."
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## Star Cluster Ejected From Galaxy At 2,000,000 MPH

• #### Velocity (Score:5, Interesting)

on Friday May 02, 2014 @09:34AM (#46898509)

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: (Score:3, Interesting)

It would take a ship travelling at that speed roughly two days to travel from Earth to the Sun (1 AU). In those terms it doesn't seem all that fast. Pedestrian, really.

• #### Re:Velocity (Score:5, Funny)

by Anonymous Coward on Friday May 02, 2014 @10:43AM (#46899101)

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: (Score:3)

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

1) You won't be dissing those "imperial units" once the Death Star is finished!
2) I have it on good authority [youtube.com] that everything is already moving at 12,000,000 a minute so yes, 2 million miles an HOUR does seem "pedestrian".

I'll save you the trouble on the numbers:
http://en.wikipedia.org/wiki/Galaxy_Song [wikipedia.org]

• #### Re: (Score:2)

I'm sure all would be happier if this were expressed in more familiar units

555.55 miles per sec
894.08 kilometers per sec
2300 times the muzzle velocity of a S&W 40 cal bullet
2600 times the speed of sound
2.1 E4 times the speed of a fastball
8.7 e4 times the speed of Usain Bolt
2 e13 times the speed of grass growing
5.376 E9 furlongs per for fortnight

• #### Re: (Score:2)

Here's a few more:

160,000 times the top speed of a Segway
500,000 times faster than a senior on a scooter
6.67 E07 times faster than a garden snail
1.11 E15 times faster than Europe and North America are drifting apart
infinity times faster than the U.S. Congress

• #### Re: (Score:1)

2 mil miles per hour is something like 1000 km/s. Considering that the escape velocity on the surface of the Sun is something like 600km/s that's not pedestrian at all.
• #### Re: (Score:1)

I had to convert 2,000,000 MPH into M/s to understand how fast this actually was in the context of space. #EVEproblems

• #### Re:Velocity (Score:5, Interesting)

on Friday May 02, 2014 @10:13AM (#46898841)

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: (Score:2, Interesting)

would we notice the effects of such an ejection?

Effects will depend on the differences of acceleration of different parts of the cluster. Because the speed has probably increased over many millenia, and because it is still a cluster, they were most likely very hard to observe.

• #### Re:Velocity (Score:5, Interesting)

on Friday May 02, 2014 @12:26PM (#46900243) Journal
Frederik Pohl's The World at the End of Time [wikipedia.org] deals with the ejections of solar systems on a grand scale.
• #### Re: (Score:2)

That wasn't so much ejection as packing bags and leaving. (Not really a spoiler, this was revealed early in the book.)

• #### Re: (Score:2)

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?

On a related note, I have been wondering if a civilization, that manages to populate an entire galaxy could use such ejections to spread to other galaxies.

• #### Re: (Score:2)

I think if a civilization had the technology to spread across a galaxy there would be better means of travel.
Think about it. Our galaxy is relatively small in it is 100,000 ly in width and 20,000 ly in height. Right now we can't even get to our nearest neighbor(Alpha Centauri) in a lifetime. If we could spread across a galaxy, there would be some other amazing form of travel that would make sling-shotting around a black hole look like taking coach.
• #### Re: (Score:2)

Right now we can't even get to our nearest neighbor(Alpha Centauri) in a lifetime.

Being able to do that would require some major technological advances. But if mankind can successfully colonize a planet orbiting any of the closest stars, then I don't think nearly as large technological advances would be needed to continue throughout the rest of the galaxy. It would basically just be doing the same thing over again using known technology. It may take a long time.

If the trip takes one generation, colonizat

• #### Re: (Score:3)

IANAA, but I would not be shocked to learn that being anywhere close enough to a black hole to cause this galactic ejection would mean sterilization via gamma radiation from the other matter being ripped apart and then colliding with other matter in the accretion disk. There are so many high-energy events going on near a black hole that irradiation seems very likely to me.

• #### Re: (Score:1)

I think that if we were in such a cluster (thousands of stars within a few dozen lightyears) the night sky would be spectacular. Of course, our instruments would measure that the fainter stars far away, the ones of our 'old' galaxy, would move, but I think that 99% of the population wouldn't notice any difference. As to interstellar travel, with such a huge number of stars that close by, I guess we would have enough interesting destinations for quite a while.
• #### Re: (Score:1)

I wonder if the Earth was...would we notice the effects of such an ejection

We'd all have Don King hair [blacksportsonline.com].

• #### Re:Velocity (Score:5, Funny)

on Friday May 02, 2014 @11:01AM (#46899279)
So that would be 48.5 megaSmoot/semester, based on the conventional 39 hour semester
• #### Re: (Score:1)

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

Well it is approximately 0.00298c, so taking into account that the speed reading only has one significant digit, the speed of the star cluster might very well be above 0.003c.

• #### Re: (Score:2)

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.

There's definitely more that 1.21 gigawatts of energy involved....

• #### Re: (Score:2)

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

Agreed.

My preferred rule of thumb for "is that fast?" is to work out how fast an object traverses it's own diameter. In this case, for an individual star, about a half an hour for a sun-size star. A lot, lot more than that for the entire cluster/ cluster core.

• #### 12 Parsecs (Score:1)

by Anonymous Coward

This is at least 12 parsecs.

• #### Re: (Score:1)

Parsec is a unit of distance (like light-years), without an expression over time it is not defining any speed.
• #### Re:12 Parsecs (Score:5, Informative)

on Friday May 02, 2014 @11:30AM (#46899611) Homepage

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.

• #### Re: (Score:1)

I know it's from the movie, but in the movie he is referring to the optimized distance travelling through the Maw Cluster and not time directly. [wikia.com]
• #### Re: (Score:1)

by Anonymous Coward

Now that's just sad.

• #### Reads like a TMZ.com headline (Score:3)

on Friday May 02, 2014 @09:39AM (#46898543)
If Star Cluster was a rap posse and Galaxy was a club.
• #### Re: (Score:1)

I was thinking the star cluster was a bachelorette party :-P
• #### If it's not too much to ask (Score:5, Funny)

<arancaytar.ilyaran@gmail.com> on Friday May 02, 2014 @09:41AM (#46898553) Homepage

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 (Score:5, Funny)

on Friday May 02, 2014 @09:48AM (#46898619)
Remember that 1 lightyear = 1.03461597 × 1014 American football fields.
• #### Re: (Score:3)

The superscript didn't work. edit: 10 ^ 14
• #### Re: (Score:3)

Hey, I'm European. We don't have those imperial units here. How much Romes per day is one Library of Congress per fortnight?
• #### Re: (Score:2)

Hey, I'm European. We don't have those imperial units here. How much Romes per day is one Library of Congress per fortnight?

Roughly 8 million olympic size swimming pools per menstrual cycle.

• #### Easy to understand units (Score:1)

by Anonymous Coward

This handy converter for changing all sorts of units into something easier to understand
http://www.theregister.co.uk/Design/page/reg-standards-converter.html#velocity
tells us that 2,000,000 mph is 29.8225% of the maximum velocity of a sheep in a vacuum.

• #### They didn't pay the rent? (Score:5, Interesting)

on Friday May 02, 2014 @09:42AM (#46898567) Homepage Journal

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? (Score:4, Funny)

on Friday May 02, 2014 @09:49AM (#46898629)
It was an old, run down section of the galaxy.
• #### Re:They didn't pay the rent? (Score:5, Funny)

on Friday May 02, 2014 @10:10AM (#46898815) Homepage Journal

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: (Score:2)

They make their own ghettos...just sayin ;-)
• #### Re: (Score:2)

The cluster was wearing Google Glass.

• #### Re: (Score:2)

Unfortunately, all the passengers would be smushed to a 1 mm thick puddle in the back of the capsule. That is if we got them to that speed in a lifetime. Or maybe not. I need to go do some more math.
• #### Re:They didn't pay the rent? (Score:5, Informative)

on Friday May 02, 2014 @10:39AM (#46899071)
Nah, at a constant 1 G acceleration you could get to 2 M mph in under 51 hours.
• #### Re: (Score:2)

Even the speed of light does not seem so fast when compared to 1G. c / 1G = 354 days. The implication of that is that at 1G acceleration, you'd reach relativistic speed in less than one year.
• #### Re: (Score:2)

Only if you assume that Newtonian mechanics apply, which they won't. When estimating acceleration for something like 0.003c, you can disregard relativistic effects, but not when you get anywhere near c. At that point, the velocity needs to be computed through general relativity, which is fiendishly more complicated than just v/a.
• #### Re: (Score:2)

At that point, the velocity needs to be computed through general relativity, which is fiendishly more complicated than just v/a.

Doing that division is no problem, and the result you will get is 354 days. Next one has to interpret the result. Now look carefully at what I said about the interpretation of that division. I said you'd be moving at relativistic speed after less than one year.

The definition of relativistic speed is that you are moving so fast, that Newtonian formulas are no longer a good approx

• #### Re: (Score:3)

At that point, the velocity needs to be computed through general relativity, which is fiendishly more complicated than just v/a.

Actually, it's just v = c*tanh(a*T/c) [ucr.edu].

• #### Re: (Score:2)

The fastest we've ever been about to propel something is 24,000 mph

Actually, Wikipedia says Voyager 1 is travelling at 38,350 mph.

• #### Re: (Score:1)

One problem with that is that whatever system we used would have to have two ends. One to get us up to 2 million MPH and another to stop us.

i.e. since the summary mentions two supermassive black holes probably having something to do with getting to that speed, we'd probably need something similar or equivalent to slow down within a reasonable timeframe from that speed.

Doing something like that within our solar system would be somewhat difficult I think. Even if we could somehow compact that much power into

• #### Re: (Score:1)

by Anonymous Coward

They're being vague because they are scientists and they don't know precisely how it happened. Basically, a scientist took a picture of something very far away and hypothesized what was in the picture based on other pictures and theories. As far as what force was involved... If the picture is right, if the hypothesis of what's in the picture is accurate, then a scientist might hypothesize that the accelerating force was gravity, and try to construct a model of that galaxy to fit that hypothesis or alter

• #### Slingshot effect (Score:3, Funny)

by Anonymous Coward on Friday May 02, 2014 @09:45AM (#46898599)

"The black holes then acted like a slingshot, flinging the cluster away at a tremendous speed."

... and then the star cluster went back in time and saved the whales from extinction.

• #### Can anyone explain... (Score:3)

<markt&lynx,bc,ca> on Friday May 02, 2014 @09:50AM (#46898637) Journal
... if two spaceships counterclockwise in a circular path such that they are always on opposite side of the circle at relativistic speeds, looking out of the window at the other spaceship, because it appears to be travelling in the opposite direction, its speed is going to appear to be $\sqrt{2*v^2}/c$, and its clock should appear to be going more slowly than your own, right? So if both spaceships perceive that the other's clock is moving more slowly, what will they perceive if the spaceships come together to compare clocks? Will the clock on the other ship suddenly appear to be going faster than normal?
• #### Re:Can anyone explain... (Score:4, Interesting)

on Friday May 02, 2014 @10:00AM (#46898723) Homepage

You say it "appears to be travelling in the opposite direction," but does it? It never gets any closer or any further away. Both ships are travelling around a common center, but relative to each other, are they in fact (as far as time dilation is concerned) stationary?

So if both spaceships perceive that the other's clock is moving more slowly, what will they perceive if the spaceships come together to compare clocks?

You can simplify (or in the light my above thought, perhaps even "make valid") this particular question a bit by considering the twin paradox instead. The same thing happens - the twin who stays at home considers the travelling twin's clock to be slower, but so does the traveller. And it's the same on the home trip, too, even though the traveller is now moving towards the stay-at-home. What breaks the symettry of the situation is that only one of them undergoes acceleration at the start, turnaround, and end points.

If the traveller had stayed at Alpha Centauri and his lazy twin had ventured out to follow him at the same speed, their clocks would match.

I suspect that the same applies to the circling ships - the clocks will match if neither breaks symmetry, otherwise they won't. And if the symmetry break is done only at non-relativistic speeds - i.e., both twins slow to a stop, then one tootles over to the other at 10km/h - the clocks will practically match.

• #### Re: (Score:2)

What breaks my spelling of the word "symmetry" is another matter entirely.

• #### Re: (Score:2)

That point bears emphasising: in relativity, an accelerating object is distinct from the rest of the universe.

• #### Re: (Score:2)

It's Friday and I've had a long day. Why you gotta go putting conceptual bombs like that in my brain?

• #### Re: (Score:2)

Don't worry, general relativity makes the laws of the universe equivalent for all reference frames again. Of course, then you're dealing with general relativity.

• #### Re: (Score:2)

But those spaceships would be under constant acceleration. Their velocity is changing direction as they travel around the black hole.

• #### Re: (Score:2)

I don't remember anyone mentioning a black hole! In any case, they're both accelerating in an exactly opposite and symmetrical manner. There'd be no way to determine which of the two spaceships you were on if you were randomly teleported onto one of them (unless you had details of their positions at a particular time, so let's pretend you don't, or there are no useful navigational markers) so there can be no difference in their clocks if they meet up in a symmetrical way (and no practical difference if they

• #### Re:Can anyone explain... (Score:5, Informative)

on Friday May 02, 2014 @10:26AM (#46898951)

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.

• #### Any sign of Pierson Pupeteers? (Score:1)

by Anonymous Coward

What is the configuration of the star cluster?

• #### 2 million miles an hour ? (Score:3)

on Friday May 02, 2014 @09:55AM (#46898689)
Why not just use per second (I won't even harp on using 900 km.s-1 at that point it seems neigh useless) and compare to speed of light (that's about 0.3% of speed of light by the way) or other astronomical measurement.
• #### For the last time (Score:4, Funny)

on Friday May 02, 2014 @10:02AM (#46898735) Homepage
Don't come back!
• #### "Towards" at negative velocity? (Score:2)

A Globular Cluster Toward M87 with a Radial Velocity

Why don't they say "away from" at "(+)1000 km/s"? (if I've got that right; the somewhat hilarious "artist's impression" indicates, as does the headline, that the cluster is moving away from M87).

What's the significance of the negative velocity?

• #### Another Question (Score:4, Interesting)

on Friday May 02, 2014 @10:26AM (#46898947)
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.
• #### Why wouldn't the dark matter simply go along? (Score:1)

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.

Why would the dark matter stay when the rest of the cluster goes?

• #### Marrow (Score:2)

Come to think of it, this would be a great way to travel between galaxies. This would be an excellent Intergalactic Spacecraft!
• #### Re: (Score:1)

Let's call it an Intergalactic Bypass. Let's put a little sign next to it, saying "Don't Panic, next stop...the restaurant at the end of the universe."
• #### Re: (Score:2)

Not really. 2 million MPH is only like .003c, and the nearest galaxy to us is Andromeda, 2.5 million light-years away. You'd still be looking at a good 833 million years to get there.

Interstellar distances are huge. Intergalactic distances are brain-destroyingly huge.

• #### Re: (Score:2)

Not really. 2 million MPH is only like .003c, and the nearest galaxy to us is Andromeda, 2.5 million light-years away. You'd still be looking at a good 833 million years to get there.

True, at least you would be traveling in style, if you could live that long.

Interstellar distances are huge. Intergalactic distances are brain-destroyingly huge.

Absolutely. Distances withing the cluster would be interesting, considering the black holes compressed them together.

• #### Re: (Score:2)

Absolutely. Distances withing the cluster would be interesting, considering the black holes compressed them together.

Not so ; the suggestion is that the black hole interactions stripped the outer parts of the cluster off, leaving the most-tightly bound core region.

• #### Re: (Score:2)

Absolutely. Distances withing the cluster would be interesting, considering the black holes compressed them together.

Not so ; the suggestion is that the black hole interactions stripped the outer parts of the cluster off, leaving the most-tightly bound core region.

The distances between the stars within the most-tightly bound core region, ejected is what I was interested in.

I read the main article however the summary says (compressed into a space just a few dozen light-years apart) I must have missed where the suggestion was made about stars being striped off, but it's very interesting. You can only imagine what that would look like over millions of years. Thanks for pointing it out.

This is one of the reasons I love about being a geek and getting excited about the

• #### Towards Us (Score:5, Informative)

on Friday May 02, 2014 @10:29AM (#46898977)

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: (Score:2)

This might be how advanced civilizations do space travel.

Oblig: I for one, welcome our new cluster-slinging galactic-traveling overlords!

• #### Re: (Score:1)

This might be how advanced civilizations do space travel.

No, it's how cheap civilizations do it. Advanced ones want a way to change their mind and turn back.

• #### Wan-Tu has been Busy - World at the End of Time (Score:1)

by Anonymous Coward

Frederick Phol
http://en.wikipedia.org/wiki/The_World_at_the_End_of_Time

An Interstellar Being that lives in the heart of a star "Flings" a cluster of Stars out of his Galaxy and far into the Future due to Time Dilation. On one planets that orbits one of the Stars lives a new colony of humans, cut off from Earth they come to understand something is wrong with their new home and the Universe recedes far into the past. Meanwhile one of the original colonists proceeds to "Time travel" himself due to cryonics sti

• #### They know something (Score:3)

<Todd_Lewis@unc.edu> on Friday May 02, 2014 @10:31AM (#46898995) Homepage
Sounds like M87's Puppeteers know something and are heading for higher ground.
• #### Hard to imagine cluster holding together... (Score:4, Interesting)

<thadbeier@gmail.com> on Friday May 02, 2014 @10:38AM (#46899051) Journal

For a three-body slingshot to work, the object would have to get pretty close to one or both of the black holes -- considerably closer than the size of a globular cluster. At that distance, the tidal forces around the black holes would rip the cluster apart. I just can't see this happening.

I suppose it's time to do some simulations :)

• #### Re: (Score:1)

For a three-body slingshot to work...

Yikes! Do not google that at work without safety settings

• #### Re: (Score:2)

For a three-body slingshot to work...

Yikes! Do not google that at work without safety settings

Damn, I wish I could mod that comment funny - and informative!

• #### Pedantic rant (Score:1, Flamebait)

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.

I always have issues with astronomical articles that say something *is* happening, especially when the observation is of a structure 53.4 million light years away. *Was* happening, sure. *Is* happening? Don't think so...

• #### Re: Pedantic rant (Score:1)

by Anonymous Coward

I always have an issue with pedantic neck beards that don't understand that from our pov, it is happening.

• #### In other words (Score:2)

it got cluster fscked

• #### The Cluster replies, (Score:4, Funny)

on Friday May 02, 2014 @11:44AM (#46899789)

"I've been thrown out of classier places than this!"

• #### Galactic Bullying. (Score:2)

"...The star cluster wandered too close to the pair...

"...The black holes then acted like a slingshot, flinging the cluster away at a tremendous speed."

For some reason I'm picturing two bullies who just caught the new freshman kid walking home from school...

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