Yes, I get that Sag A is pretty quiet. But there was an X-ray flash about 60 years ago, based on echos seen in Chandra images. Also, there is this: <a href="http:&#x2F;&#x2F;www.space.com&#x2F;19748-hypervelocity-stars-milky-way.html" rel="nofollow">http:&#x2F;&#x2F;www.space.com&#x2F;19748-hypervelocity-stars-milky-way.htm...</a><p>The impact description in <i>Killing Star</i> is similar to xkcd&#x27;s, for what it&#x27;s worth.