According to reports published in The Astronomer’s Telegram, a star in the region of the constellation Cassiopeia has just passed again, 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 it and point it in that direction.
The first detection was made on March 18, 2021 by amateur astronomer Yuji Nakamura, of Mie Prefecture, Japan. In four frames captured with a 135-millimeter lens and a 15-second exposure, a bright glow of 9.6 degrees magnitude was visible, where none had been just four days before.
The finding was quickly reported to the National Astronomical Observatory of Japan and scientists set to zero to find out what was going on.
Using the Seimei Telescope at Kyoto University, NAOJ and Kyoto University astronomers made spectroscopic observations and used the 0.4-meter telescope at Kyoto University for multicolored photometric observations.
They confirmed that the event is what we classify as a new classic, the most common of the stellar explosions, and gave it the name V1405 Case.
A new classic is not the huge kaboom of a massive star, but an explosion on the surface of a white dwarf with a main sequence binary companion in a nearby orbit, usually less than 12 hours. As the two stars revolve around each other, the small, dense white dwarf siphons the hydrogen of its larger, spongier companion.
This hydrogen ends up in the atmosphere of the smallest star, where it heats up. When hydrogen becomes hot and dense enough, nuclear fusion is activated on the surface of the white dwarf, releasing an enormous amount of energy that explosively expels unburned hydrogen into space.
Unlike a type Ia supernova, in which the white dwarf explodes, both stars survive and continue their strange relationship to re-explode another day. The new news may continue to shine for a few days or months.
It is unclear which star produced V1405 Case, but there is a strong candidate: the eclipsing (binary) variable star CzeV3217, which is approximately 5,500 light-years away from the solar system.
Further observations will help astronomers better understand the news and confirm that the source is CzeV3217.
(Yuji Nakamura / NAOJ)
Because stellar explosion events like these are so unpredictable, they are not always easy to catch quickly, so the discovery of the V1405 Case is quite exciting.
If you want to get out there and try to see for yourself, its coordinates are in straight ascent 23 24 47.73, declination +61 11 14.8, not far from the star Cassiopeia Caph and at an even greater distance short of star type B 115566.
While you are out, keep your eyes open for anything out of the ordinary …