Black Widow and Redback Pulsars

Spinning 390 times a second, PSR J1311−3430 periodically swings its radio (green) and gamma-ray (magenta) beams past Earth in this artist's concept. The pulsar heats the facing side of its stellar partner to temperatures twice as hot as the sun's surface and slowly evaporates it. Credit: NASA's Goddard Space Flight Center
Pulsars have been known for their large rates of rotation and intense gravitational and magnetic fields. Plenty of interesting things occur when pulsars are paired with another companion. Most pulsars rotate with rpms of  about few thousand when they are young. They come into existence after a star has burned all of its hydrogen fuel and it collapses under the gravitational force when it over comes the pressure gradient. This leaves a very dense core many times the mass of the sun but a fraction of its size. Roger Romani, a member of the Kavli Institute for Particle Astrophysics and Cosmology states that black widow and redback pulsars are essentially millisecond pulsars (with a rotation completed in a millisecond) with normal companion stars that are low mass. Black widow systems have companion stars much lower in mass and size than the redbacks. One black widow system named PSR J13113430, has the tightest orbit of pulsars currently known, where the companion star (a dozen or so Jupiter masses and 60 percent the size of Jupiter) orbits every 93 minutes. These millisecond pulsars are also thought to have gone to such speeds due to their interaction with a companion. But then, how did isolated millisecond pulsars rejuvenate their speeds? This is where the devouring of the companion comes into play. When the companion star faces the pulsar it receives its high energy emissions and winds which heat and blow off the material from the star. Effectively producing a vanity mirror that then is degraded over time which provides important information about the emissions of the pulsar in great detail. Romani began to image another black widow system in the visible range and saw that the color changed from intense blue to dull red, or hot to cold within an hour an a half. The blue side had temperatures of about 12,000 C whilst the original temperature of the star was around 2,700 C. Other systems have also been detected in Keck and Gemini, noticing that the blow torch of the pulsar does not uniformly heat up the surface because of the observation of flares. The systems are then permeating with ionized gas, which absorbs radio waves and causes detection of pulses to have brief and irregular intervals. But gamma rays pierce the veil of ionized gas, since their energies are much larger than the absorption energies. And over time, these millisecond pulsars "devour" their companion, leaving isolated millisecond pulsars. Or so goes this theory. Source