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In the middle of the 20th century, an unusual star was spotted in the constellation of Canes Venatici. Astronomers determined that this object, dubbed AM Canum Venaticorum (AM CVn) was, in fact, two stars. These stars revolve around each other every 18 minutes, and are predicted to generate gravitational waves, ripples in space-time predicted by Einstein. The name AM CVn came to represent a new class of objects where one white dwarf star is pulling matter from a very compact companion star, such as a second white dwarf. The two binary systems, J0751 and J1741, were observed in X-rays by NASA's Chandra X-ray Observatory and ESA's XMM-Newton telescope. As the two white dwarfs orbit around each other, gravitational waves will be given off causing the orbit to become tighter. Eventually the smaller, heavier white dwarf will start pulling matter from the larger, lighter one, forming an AM CVn system. The optical observations were critical in identifying the two white dwarfs in these systems and ascertaining their masses. The X-ray observations were needed to rule out the possibility that J0751 and J1741 contained neutron stars. Release date December 17, 2013.
