Using the Giant Metrewave Radio Telescope ( GMRT ) , we have discovered PSR J0514 - 4002A , a binary millisecond pulsar in the globular cluster NGC 1851 .
This pulsar has a rotational period of 4.99 ms and the most eccentric pulsar orbit yet found : e = 0.89 .
The orbital period is 18.8 days , and companion has a minimum mass of 0.9 M _ { \odot } ; its nature is presently unclear .
After accreting matter from a low-mass stellar companion , this pulsar exchanged it for its more massive present companion .
This system presents the strongest evidence to date of such a process .