A Groundbreaking Discovery by FAST

In an exciting astronomical feat, the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) in China has uncovered a brand-new millisecond pulsar, now labeled PSR J2129-1210O. This celestial gem was previously overlooked due to its spin period coinciding almost perfectly with that of the established pulsar PSR J2129+1210A.

What Are Pulsars?

Pulsars are extraordinary entities in our universe—rotating neutron stars that emit beams of electromagnetic radiation as they spin. Among them, millisecond pulsars (MSPs) stand out, boasting rotation periods under 30 milliseconds. They are believed to form in binary star systems when a massive star collapses into a neutron star, gaining rapid rotation as it siphons material from a companion star.

The Perfect Hunting Ground: Messier 15

Astronomers have long cast their eyes on globular clusters (GCs), rich regions filled with pulsars, and NGC 7078, better known as Messier 15 or M15, tops the list. At a staggering distance of about 35,700 light-years, M15 is one of the universe’s oldest core-collapsed clusters. Simulations predict it harbors the highest number of pulsars in the area explored by FAST.

An Intensive Search Yields Results

Headed by Yinfeng Dai from Guizhou University, a dedicated team of astronomers launched an observational campaign using FAST, running from November 2019 to February 2024. Their diligent efforts paid off when they identified a pulsar with a spin period of approximately 11.07 milliseconds, dubbed M15O. It was previously undetected mainly due to its spin period being so close to that of M15A.

Challenges of Detection

The researchers explained, "When the timing of a new pulsar is similar or overlaps with that of a known one—particularly regarding their dispersion measure (DM)—traditional algorithms struggle to distinguish them. This phase-alignment ambiguity often results in new pulsars being missed entirely during standard screening processes."

Exciting Data Ahead!

Further findings revealed that M15O has a dispersion measure of around 67.44 pc/cm³. Its proximity—just 0.37 arc-seconds from the cluster center and a mere 0.81 arc-seconds from M15A—positions it as the closest known pulsar to M15's optical center.

More Discoveries on the Horizon!

Apart from M15O, the FAST observations have revealed two additional pulsars, PSR J2129+1210M and PSR J2129+1210N (or M15M and M15N). Astronomers are set to unveil the details of these discoveries in an upcoming research paper, ramping up excitement in the astronomical community.