Last week, a new nova (and no, that’s not redundant here) was spotted in the southern sky. Nova Reticuli 2020 is not visible from the US, as Earth is in the way, but it is a nova visible to the naked eye – a rarity. First reported by Robert McNaught of the Australian National University, it has been confirmed by other observers and associated with a known variable star system, MGAB-V207.
A nova like this occurs in a binary system of a main sequence star and a white dwarf star. The white dwarf gradually draws off hydrogen from the main star over time. When it accumulates enough hydrogen, a nuclear fusion reaction is initiated, much like the reactions within the star itself. This lasts only for a brief time, however, as the accumulated hydrogen is quickly burned through. So what we see is a sudden burst of light from a previously dim (in this case, invisible to the naked eye) star.
Novae are traditionally named for the year and the constellation in which they’re spotted – the nova may have nothing to do with the stars that make up that pattern, as in this case, but it’s a convenient way to keep track of what part of the sky it’s in. Reticulum is a small and not particularly well-known constellation, named for a reticle, a grid that appears as a part of a telescope used to assist focusing.
Read more about the nova: