According to reports in The Astronomer’s Telegram, a star in the region of the constellation Cassiopeia pas nova, and the glow is still visible in the night sky. If you live in the Northern Hemisphere and even have a basic telescope, you may want to point in that direction.
The first detection was done on March 18, 2021 by amateur astronomer Yuji Nakamura of Mie Prefecture in Japan. In four frames captured with a 135 millimeter lens and a 15-second exposure, a bright glow of 9.6 was visible, just four days earlier.
The find was quickly reported to the National Astronomical Observatory of Japan, and scientists reset to find out what was going on.
Using the Kyoto University’s Seimei Telescope, NAOJ and Kyoto University astronomers made spectroscopic observations and used the Kyoto University’s 0.4-meter telescope for multicolor photometric observations.
They confirmed that the event is indeed what we classify as a classic nova, the most common of the star explosions, and gave the name V1405 Cas.
A classic nova is not the big cape of a massive star, but an explosion on the surface of a white dwarf with a main sequence binary companion on a narrow orbit – usually less than 12 hours. As the two stars revolve around each other, the small dense white dwarf sifts hydrogen from its larger, fluffier companion.
This hydrogen ends up in the atmosphere of the smaller star, where it is heated. When the hydrogen becomes hot and dense enough, nuclear fusion is caused on the white dwarf’s surface, releasing a tremendous amount of energy that the unburned hydrogen explosively expels into space.
Unlike a type Ia supernova, in which the white dwarf explodes, both stars survive and their strange relationship continues, to explode again one day. The nova itself may continue to glow for a few days or months.
It is not immediately clear which star V1405 Cas produced, but there is a strong candidate: the obscuring variable (binary) star CzeV3217, which lies about 5,500 light-years from the solar system.
Further observations will help astronomers better understand the nova and confirm that the source is indeed CzeV3217.
(Yuji Nakamura / NAOJ)
Because such explosive events are so unpredictable, it is not always easy to catch up quickly, and the discovery of V1405 Cas is quite exciting.
If you want to get there and try to see it for yourself, the coordinates on the real ascension are 23 24 47.73, declination +61 11 14.8 – not far from the Cassiopeia star Caph, and another shorter distance from the B-type star HIP 115566.
While you are out there, keep your eyes open for anything unusual …