According to reports in the Astronomer’s Telegram, a star in the Cassiopeia constellation region has just gone nova, and the cry is still visible in the night sky. If you live in the Northern Hemisphere and even have a basic telescope, you might want to go out and mark it that way.
The first discovery was made on March 18, 2021 by amateur astronaut Yuji Nakamura from the Mie Prefecture in Japan. In four frames captured using a 135-millimeter lens and a 15-second exposure, clear, 9.6 magnitude glue was seen where none had been seen just four days previously.
The discovery was quickly sent to Japan’s National Astronomical Observatory, and scientists stepped in to find out what was going on.
Using Kyoto University’s Seimei Telescope, astronomers at NAOJ and Kyoto Universities made spectroscopic observations, and used the Kyoto University’s 0.4-meter telescope for multicolor photometric observation.
They confirmed that the event was in fact what we classify as a classic nova, the most common of the stellar explosions, and named it the V1405 Cas.
The giant kaboom of a giant star is not a classic nova, but an explosion on the surface of a white dwarf with a prime order binary companion on a close orbit – usually less than 12 hours. As the two stars orbit each other, the thick white dwarf moves hydrogen from the larger and more fluffier partner.
This hydrogen ends up in the atmosphere of the smallest star, where it is heated. When the hydrogen becomes hot and dense enough, nuclear melting is stimulated on the surface of the dwarf dwarf, releasing a lot of energy that sends the hydrogen unburned into space.
Unlike the Type Ia supernova, in which the white dwarf explodes, the two stars survive and follow the strange relationship, to explode again another day. The nova itself can keep shining for a few days or months.
It is not immediately clear which star made the V1405 Cas, but there is a strong candidate: the eclipsing (binary) variable star CzeV3217, which lies at an estimated 5,500 light-years from the Solar System.
Further studies will help astronauts gain a better understanding of the nova, and confirm that CzeV3217 is indeed the source.
(Yuji Nakamura / NAOJ)
Because stellar explosion events like this are so invisible, they are not always easily captured, so the discovery of the V1405 Cas is very encouraging.
If you want to get out there and try to see for yourself, its coordinates are at a proper ascent 23 24 47.73, resolution +61 11 14.8 – not far from the star Cassiopeia Caph, and even distance shorter than star type B HIP 115566.
While you’re out there, keep your eyes peeled for anything out of the ordinary …