Bright Nova Discovered in Hercules Shone for Only 24 Hours Before It Disappeared

A nova is a galactic equivalent of a flashbang – an immensely powerful explosion of light and energy that is only visible for mere days before fading away. But a recently discovered nova has broken all previous records by fading away from view within just 24 hours. Discovered by amateur astronomer Seidji Ueda on June 21, 2021, the V1674 Herculis nova was seen on the border of the constellation Hercules the Hero that it shares with Sagitta and Aquila. 

"The white dwarf that exploded is massive and growing in mass toward a Supernova 1A explosion," astronomer Sumner Starrfield of the University of Minnesota said. "It ejected far less mass than necessary to be accrete by the white dwarf and initiate an explosion."

Novae explosion happens in binary star systems when one of the stars transforms into a white dwarf and starts to accrete matter from its gravitationally bound partner star. The matter from the star compresses under the immense gravity and pressure on the surface of the white dwarf and explodes in a nuclear fusion reaction. These flashes of light are bright enough to be mistaken as the birth of new stars though unlike stars the light does fade away from the explosion after some time. While some novae can have recurrent explosions most novae are classical nova, which does not explode multiple times. 

"We are continuing to observe this system since it has not returned to quiescence," added Starrfield. "We know that it has a ~500-second oscillation—presumably the white dwarf rotation period — and an about 3.6-hour rotation period that is probably the rotation period of the binary. We need more spectroscopy and photometry to better understand those periods and the implications of those periods."

Further observations about Nova Herculis 2021 were made using the Large Binocular Telescope in Arizona along with its PEPSI spectrograph to understand more about the explosion. Novae are hypothesized to be critical in spreading heavier elements across the galaxy and also metals like Lithium in main-class stars like our Sun.