Astronomers have unraveled the enigmatic behavior of a deceased star that is voraciously consuming its stellar companion.
Situated roughly 4,500 light-years away, this peculiar pulsar, known as PSR J1023+0038 or J1023, periodically emits beams of radiation as it spins rapidly. It has baffled scientists with its alternating states of brightness, but a team of researchers may have finally cracked the code. They discovered that the pulsar’s brightness shifts are the outcome of expelling matter over incredibly brief intervals.
The leader of the research team, Maria Cristina Baglio, explains that the phenomenon observed resembles the ejection of vast quantities of matter, akin to cosmic cannonballs, from a compact, high-speed celestial object. This object, a neutron star, experienced a gravitational collapse, resulting in its extremely dense composition.
Neutron stars, remnants of massive stars, possess intense rotational speeds due to their collapsed cores. These spins cause them to emit radiation beams like pulsars, displaying remarkable precision in timing. Additionally, their gravitational collapse can lead to magnetic field amplification, creating some of the universe’s most potent magnetic fields.
J1023 stands out even among these extraordinary remnants. Over the past decade, astronomers have observed it siphoning material from its companion star, forming an accretion disk around itself. As the pulsar switches between high-power and low-power modes, it emits varying levels of radiation.
Baglio’s team, employing multiple telescopes, observed the pulsar’s mode-switching over 280 times. They determined that the phenomenon is a result of the interaction between the pulsar’s wind of particles and infalling matter. In its low-power mode, J1023 expels matter through a narrow jet perpendicular to the accretion disk. This expelled material heats up upon encountering the pulsar wind, prompting the high-power mode.
Gradually, the pulsar’s jet dislodges the heated material, propelling it away like cosmic cannonballs. As this material diminishes, the system dims, returning to its low-power phase.
While this riddle appears solved, astronomers are not finished observing J1023. The upcoming Extremely Large Telescope (ELT) in Chile’s Atacama desert could provide unprecedented insights into the switching mechanisms of this celestial phenomenon. According to research co-author Sergio Campana, the ELT could help them understand how inflowing matter around the pulsar is influenced by its mode-switching behavior in terms of abundance, dynamics, distribution, and energetics.
