Assertion: pulsar | /r/HasProperty | psr b1257
Facets:
Source sentences:
text: The first extrasolar planets were discovered around a pulsar, PSR B1257+12.
text: The finding represents the missing piece in a puzzle that arose in 1992, when Aleksander Wolszczan of Pennsylvania State University found three planets circling a pulsar called PSR B1257+12.