[ExI] Gravitational waves made by colliding neutron stars found

[John Clark]

​The rumors were true. ​
On
​ ​
Aug 17 at 8:41 a.m. Eastern Daylight Time
​ ​
(Aug 18 12:41: Universal Time) LIGO and VIRGO detected a Gravitational Wave
coming from the collision of 2 neutron stars  of 1.1 and 1.6 solar masses.
​ ​
LIGO/VIRGO immediately alerted other astronomers to look at the region
around galaxy
​ ​
NGC 4993
​ ​
130 million light years away for anything unusual, but the orbiting Chandra
X-ray Observatory
​ ​
had already found a short gamma ray burst from
​ ​
NGC 4993. Soon after that optical astronomers in Chile and
​ ​the
Hubble Space Telescope
​ ​
saw blue spot in NGC 4993
​ ​
that wasn't there just days before, radio telescopes also
​saw​
 unusual stuff.

This time the gravitational wave lasted about 100 seconds, the Black Hole
collisions they saw before only lasted  about a second; at the start of
that 100 seconds the 2 stars were orbiting only 200 miles apart. It's not
clear if the merged object is a Black Hole or a larger Neutron star, the
transition between the 2 is thought to be between 2.5 and 4 solar masses
but the exact
​transition ​
point is not known.
​ ​But it is thought
 that the event synthesized and ejected 40 to 100 earth masses of Gold and
10 to 30 earth masses of Uranium.

Astronomers were very lucky, all 3 gravitational detectors were online at
the same time for only a few weeks but that's when this event happened, and
its the closest short gamma ray burst ever found.

https://www.ligo.caltech.edu/page/press-release-gw170817

John K Clark
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