the most massive
... that the most massive known neutron star is approximately 10 kilometres (6.2 mi) in diameter, but has a mass twice that of the Sun?
... that <b id="mwF8A"><a class="mw-redirect" href="./PSR_J1614–2230" id="mwF8E" rel="mw:WikiLink" title="PSR J1614–2230">the most massive</a></b> known <a href="./Neutron_star" id="mwF8I" rel="mw:WikiLink" title="Neutron star">neutron star</a> is approximately <span about="#mwt86" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"10"},"2":{"wt":"km"}},"i":0}}]}' id="mwF8M" typeof="mw:Transclusion">10 kilometres (6.2</span><span about="#mwt86" typeof="mw:Entity"> </span><span about="#mwt86">mi)</span> in diameter, but has a <a href="./Mass" id="mwF8Q" rel="mw:WikiLink" title="Mass">mass</a> twice that of the <a href="./Sun" id="mwF8U" rel="mw:WikiLink" title="Sun">Sun</a>?