SSO News

Published in the RSAA Lunations
Vol1 Issue7 1–31 August 2020

On July 15th, long-time Coona resident and famous comet hunter, Rob McNaught discovered a naked-eye transient in the constellation of Recticulum. The transient was soon targeted by the SALT telescope in South Africa and the ANU 2.3m telescope and classified as a classical nova, similar to Nova Sagittarii 1991. The new nova is known as Nova Recticuli 2020. The name is derived from the constellation the nova appears in and the year it was discovered.

Using data from an all sky camera operated by Andre Phillips, it was soon realised that the nova was visible to the naked eye for about a week before it was discovered. In this age of all sky digital surveys, it is amazing that no one discovered it earlier.

A nova (or “new” star) is thought to occur in a binary system consisting of a star and a compact object (see the attached picture). Material from the outer layer of the star, which consists of mostly hydrogen, is drawn onto an accretion disk and eventually settles on the surface of the compact object, which is thought to be a white dwarf. Once there is enough hydrogen, the hydrogen ignites and fuses into helium creating the nova that we see. Naked-eye nova occur once every couple of years, but this nova is rare for another reason. It is only the third time that we knew of the progenitor (a cataclysmic variable) before the explosion.

The nova has now faded to below naked eye visibility, but it easily seen in a pair of binoculars. However, you need to be keen; the nova is best visible just before morning twilight. The ANU 2.3m will continue to observe the nova as it fades.