Close stellar encounter to produce energetic fireworks

Two stars are closing in on each other, destined for a close encounter of the lopsided variety. One star is hard to miss, and the other hardly noticeable, but astronomers expect the close call to be quite the fireworks show.

The stellar encounter involves a pulsar, a small stellar remnant named PSR J2032+4127, and a massive Be star called MT91 213.

Pulsars are magnetized neuron stars noted for their diminutive size, impenetrable density and quick rotation. This particular pulsar measures just 12 miles across but weighs twice as much as our sun. It rotates seven times per second.

Be stars, or B-type stars, are a variety of supergiant stars characterized by the intensity of their stellar fusion. They are large and bright, their core encircled by a massive, swirling sphere of hot gas. Be stars typically produce intense stellar winds. MT91 213 is 15 times the mass of our sun and 10,000 times brighter.

As researchers at the University of Manchester's Jodrell Bank Center for Astrophysics recently discovered -- thanks to the Lovell Radio Telescope -- the odd, elliptical orbit of PSR J2032+4127 will send the pulsar perilously close to its companion star MT91 213, in three years.

When the pulsar passes through a portion of the Be star's surrounding gas, fireworks will ensue.

"This forewarning of the energetic fireworks expected at closest approach in three years' time allows us to prepare to study the system across the entire electromagnetic spectrum with the largest telescopes," astronomer Ben Stappers, a professor at Manchester, explained in a press release.

Researchers have been studying both of the two stars for several years, but only recently confirmed that they were part of a binary system. The delay is the result of the pulsar's extreme orbit, which sends the small remnant of star far, far away from its companion before it's finally pulled back. After the upcoming close encounter, PSR J2032+4127 won't return for another quarter century.

"This is the longest-period binary system known to contain a radio pulsar and provides an excellent opportunity to study these massive stars, important progenitors for supernovae and sources of many of the heavy elements in the Galaxy," explained lead study Andrew Lyne.

The two stars and their impending encounter are described in the journal Monthly Notices of the Royal Astronomical Society.