J1749 is the first accreting millisecond pulsar to undergo eclipses. The pulsar and its companion star are separated by 1.22 million miles, or about five times the distance between Earth and the moon. Irradiated by the pulsar's intense X-rays, the star's outer layers puff up to make it about 20 percent larger than a star of its mass and age should be. This artist's rendering includes additional data about the system.