Astronomers have observed a globular cluster known as Terzan 6 using the Green Bank Telescope (GBT). They have discovered a new millisecond pulsar that is likely associated with the cluster. The discovery was reported in a research paper published on the preprocessing server on September 17. arXiv.

Pulsars are strongly magnetized, rotating neutron stars that emit beams of electromagnetic radiation. The fastest-spinning pulsars, with rotation periods of less than 30 milliseconds, are known as millisecond pulsars (MSPs). Astronomers suggest that they form in binary systems, when the more massive component first collapses into a neutron star, which then spins upwards as matter from the secondary star accretes.

Terzan 6 is a galactic globular cluster with a collapsed metal-rich core located about 21,800 light-years away. Although the cluster has been known for decades, no pulsars have yet been discovered within it. However, the high frequency of encounters with stars suggests that it may contain dozens of such objects.

Now a team of astronomers led by Shi-Jie Gao of Nanjing University in China has reported the discovery of a new MSP in Terzan 6 that could be the first known pulsar. The discovery is the result of a targeted C-band (4-8 GHz) cluster we call GBT.

“Here we report the discovery of a 5.33 ms pulsar associated with Terzan 6, called PSR J1751–3116A,” the researchers write.

As stated in the paper, the rotation period of PSR J1751–3116A is about 5.33 milliseconds, while its dispersion measure is about 383.08 pc/cm.^-3The resulting dispersion measure strongly supports the connection between PSR J1751–3116A and Terzan 6.

The study found that the flux density of PSR J1751–3116A at 6.0 GHz was 3.0 μJ. Assuming a spectral index of -1.4, the astronomers calculated that the pulsar flux density at 1.44 GHz was about 23 μJ.

The authors suggest that PSR J1751–3116A is an isolated millisecond pulsar, consistent with its classification as a core-collapse cluster of Terzan 6. They note that PSR J1751–3116A was potentially formed through a dynamical interaction.

Ultimately, the researchers say they hope to discover more pulsars in Terzan 6 by using existing radio telescopes at higher frequencies.

“Given the extremely high frequency of stellar encounters, more sensitive searches, such as using GBT and MeerKAT (e.g. TRAPUM, a large MeerKAT search project), are expected to lead to new pulsar discoveries in Terzan 6,” the scientists conclude: