CTB-1 and its pulsar’s enigma

 

 

 

 

CTB-1, also known as Abell 85, is a supernova remnant (SNR) located in the constellation Cassiopeia, approximately 13,700 light-years from Earth. With a fairly circular shape, it presents a diameter of 34 arcmin, about 100 light years at the estimated distance. This SNR has been thoroughly studied (although it will be, for sure, revisited when new tools and methods are available, as it has been so far during the years after its discovery…). This nebula was discovered in 1960 during a radio survey. CTB-1 is rich in Oxygen and Neon, although its other main components -Hydrogen, Sulphur and others- also show intense signals.

One pretty odd aspect of CTB-1 is its remaining pulsar. For nearly six decades, the theoretically remaining pulsar after the supernova explosion was not found. In a thorough paper published in 2018 based on observations made in 2013-15, Zyuzin et al. as well as Clark et al., proposed that PSR J0002+6216 was the missing pulsar. In 2019, M. Kerr et al. (see also the full paper) determined that indeed that pulsar was what remained of the original star. They also observed a radio-conspicuous jet emanating from CTB-1 in the direction of the pulsar. In the image below (from DSS9), the trajectory of the movement and the position of the pulsar is shown with the red arrow and the yellow circle. The lower limit of the main image is shown in yellow, meaning that the pulsar is, unfortunately, outside the image.

Another interesting aspect of this pulsar is its velocity. very often qualified as an extremely fast moving pulsar, with estimated speeds of clearly above 1000 km/s (and as much as 1600 km/s by some estimates), recently -in 2023- Bruzewski et al. find that the real speed of this pulsar is around 520 km/s. This speed still keeps PSR J0002+6216 in the category of “cannonball” fast-moving pulsars, but its newly calculated velocity is not that exceptional anymore.