[ExI] Milky Way escape velocity

BillK pharos at gmail.com
Mon Apr 30 20:49:53 UTC 2012

We recently mentioned the velocity required to escape the Milky Way
galaxy - over 1 million miles per hour.

And now they've found some rogue stars moving at these tremendous
speeds and heading out of the galaxy!

Rogue stars ejected from the galaxy are found in intergalactic space
April 30, 2012

Vanderbilt astronomers have identified nearly 700 rogue stars that
appear to have been ejected from the Milky Way galaxy. When these
stars received the powerful kick that knocked them out of the galaxy,
they were small, yellow stars like the sun. But in the
multi-million-year journey they evolved into red giant stars. Credit:
Michael Smelzer, Vanderbilt University

It's very difficult to kick a star out of the galaxy.

In fact, the primary mechanism that astronomers have come up with that
can give a star the two-million-plus mile-per-hour kick it takes
requires a close encounter with the supermassive black hole at the
galaxy's core.

The article doesn't mention any planets orbiting these rogue stars,
but maybe they just didn't look for them.
And the encounter with the black hole might have torn the planets away.


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