September 28, 2012
New Work Could One Day Detect Planets Around Pulsars
Lee Rannals for redOrbit.com - Your Universe Online
Astronomer Fabrice Mottez made a series of predictions at the European Planetary Science Congress about the properties of planetary systems around pulsars.
Pulsars are dense balls of matter which are heavier than the Sun, yet only are a few tens of miles in diameter. They rotate rapidly, and give off a bright flashing light, giving them their name "pulsating star."
So far, there have been two pulsars observed that are home to planetary systems, and Mottez and his team's work has implications of how to discover these planets.
“Pulsars and their planetary systems work a bit like giant electric generators,” Mottez said. “If the conditions are right, the magnetic field and stellar wind of the pulsar can interact with planets and create a powerful electromagnetic wake around the planets.”
Astronomers may be able to see this from Earth if new methods of detecting planets are developed, helping to shed light on how pulsar planet systems evolve.
As objects radiate, they lose energy, and while the forces unleashed by the wakes around pulsar planets are not large enough to have an effect on the planets' orbits, they are expected to have more profound effects on smaller bodies like asteroids and comets.
“Depending on the direction of their orbits, asteroids and comets could be thrown out into distant orbits or dragged down onto the pulsar´s surface. Even for objects as big as a kilometer in diameter, this could happen in less than 10,000 years, which is very rapid on astronomical timescales,” Mottez said.
His work is considered to be an important step towards better understanding how circumpulsar planets form.
Pulsars are the dense cores leftover from large stars after they explode in a supernova. Supernovae are extremely violent, but planets surrounding the exploding star are thought to be able to survive the blast.
Planetary survivors like these are thought to exist around a pulsar, as well as other types.
Planets are formed from discs of matter that gradually accrete around stars, but it is thought that the debris thrown out by supernovae could provide material that triggers a second burst of planet formation around pulsars.
The disruptive effects of the electromagnetic wake on small objects could have consequences for the formation of these second generation planets.