PSR J0337+1715
PSR J0337+1715 is a millisecond pulsar discovered in a Green Bank Telescope drift-scan survey from 2007. It is spinning nearly 366 times per second, 4200 light years away in the constellation Taurus. It is co-orbiting very closely with another star, a white dwarf, with a period of 1.6 days. There is a second white dwarf further out which is orbiting both the pulsar and the inner white dwarf, and has an orbit with a period of 327 days. It thus provides an opportunity to test the nature of gravity and the strong equivalence principle, with a sensitivity several orders of magnitude greater than before.
Results were published in 2018 showing that if there is any departure from the equivalence principle it is no more than three parts per million.
