Star Flung From Milky Way at High Speed

fenimor writes "Using the MMT Observatory in Tucson, astronomers have discovered a star three times bigger than the sun, leaving our galaxy at a speed of over 1.5 million miles per hour (670 kilometers per second). The first-of-its-kind finding not only confirms an earlier theory about the existence of such speeding stars, but also reinforces the notion that the Milky Way spins around a black hole."

Comments

Re:Speed is relative

[grahamsz]

Presumably if it's leaving our galaxy then that'd be the normal way to look at it.

Alternatively maybe it's staying still and we are being flung away from it at 1.5M mph.

Re:1.5 million miles per hour!!

[merlin_jim]

I just wonder why the star and the planets are not torn apart by such huge speeds?

a) we're not sure it has planets.

b) it's not velocity that kills, it's acceleration.

c) this acceleration can only be explained by current theory if it was a gravitational acceleration.

d) gravitational acceleration acts on all elements of an object equally, meaning that there was no force from the acceleration itself acting to tear the object apart. Just like when you're in freefall, you don't feel gravity acting on you.

Now TIDAL gravity can tear objects apart, but since the gravitationally assisted acceleration likely happened in the galactic core, the tides were probably pretty gentle... the tidal force at a black hole's horizon can be expressed as a function of mass over surface area; the bigger the hole, the less the tides.

Inertia & Momentum

[mreed911]

While this seems astounding, leaving some to wonder "how's a star stay together at 1.5MM mph?", it's important to remember that, for all intents and purposes, it's travelling through NOTHING, through a vacuum. As long as its velocity is stable (not running into things to slow it down), there's no inertia to change it's shape, etc.

Is there *really* a difference, physically, on an object moving at 1.5MM mph and one standing completely still, if they're not interacting with anything else? No. Their inertias are the same, so their physical properties and interactions are the same.

Momentum, however, could be a bitch. Imagine this star slamming into another star (or, a la the Death Star, a small planet in the Aldeberan system). Ka-pow, with the graphic like on the old Batman series! Would make Levy-Shoemaker look like a BB gun (you're gonna put your eye out!)...

Re:Speed is relative

[jridley]

It's moving like hell compared to any large body in the galaxy, or the average.

I remember this story:
Professor: The temperature in this kind of reaction is about 3 million degrees.
Student: Is that Celcius or Kelvin?
Professor: It doesn't matter!

IOW, the difference between C and K at ~3m* is insignificant. In the same way, the speed of this star is practically the same from any point of reference near any star in the galaxy.

Re:milky way munching stars and galaxies

[corngrower]

there probably would be no kinetic interaction between the two if they were to "collide".

I would bet that there would be a number of stars in the galaxies that would have their motions markedly changed. You'ld probably have a number of stars being scattered around and exiting the galaxies at high velocities relative to other stars . There may even be an actual collision or two.