Unexpected Nova Just Appeared In The Night Sky – And You Can See It With The Naked Eye

For the last year or so, astronomers and sky lovers have been waiting for the explosion of T Coronae Borealis. The system is a notorious recurring nova, which is expected to go any moment now, but still has not. So, while astronomy can be a cruel mistress, making us wait, it can also be a generous mistress since there is also a brand new and unexpected nova in the night sky that you can see. Its name is V462 Lupi.

A nova is a stellar object that suddenly brightens in the night sky, usually to a level that makes it visible from Earth with much smaller telescopes or even just to the naked eye (not to be confused with a supernova). V462 Lupi is a classical nova, which means that the eruption that generated the increase in luminosity is an act of theft, and was detected on June 12. 

In the system, there is a white dwarf, the remains of a star like the Sun after it became a red giant and ran out of fuel. This dense, hot core is the white dwarf. In a system that becomes a nova, the white dwarf is not alone; there is another star in the system, usually a red giant, and the white dwarf is stealing material. The material accumulates on the surface of the white dwarf, and with mounting pressure, it detonates.

This is the cause of the nova's sudden brightness. Nova comes from the Latin for stella nova or "new star", because novae just suddenly appear, like out of nowhere. It was a much bigger deal when people believed the universe to be immutable. Suddenly getting a new star in the night sky was a lovely challenge to that worldview.

V462 Lupi is in the constellation of the Lupus (the wolf), a southern sky constellation which is visible across the whole Southern Hemisphere and up to 35 degrees latitude in the Northern Hemisphere. Which means anyone south of North Carolina has a chance to see it tonight or in the coming days.

As reported in the Astronomer Telegram, it was discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN) at 8.7 magnitude, below the average human limit for naked eye observations, even in ideal conditions. Sky & Telescope reports that this week, it has reached a 6.1 magnitude. This means it got 11 times brighter, and it's now at the edge of naked eye visibility in dark sky conditions.

The event is dramatic. The progenitor is believed to have been a 22.3 magnitude, which means the nova has made this system over 3 million times brighter than it used to be.