A star has just exploded in the sky and it is easy to observe


According to reports from The Astronomer’s Telegram, a star in the Cassiopeia constellation region has just turned nova, and the glow is still visible in the night sky. If you live in the Northern Hemisphere and have even a basic telescope, you may want to head over and point in that direction.

The first detection was made on March 18, 2021, by amateur astronomer Yuji Nakamura from Mie Prefecture in Japan. In four frames captured with a 135-millimeter lens and a 15-second exposure, a bright 9.6-magnitude glow could be seen where none had been seen just four days earlier.

The find was quickly reported to the National Astronomical Observatory of Japan, and scientists concentrated to find out what was going on.

Using the Seimei telescope at Kyoto University, astronomers from NAOJ and Kyoto University made spectroscopic observations and used the 0.4-meter telescope at Kyoto University for multi-color photometric observations.

They confirmed that the event is in fact what we classify as a classical nova, the most common of stellar explosions, and gave it the name V1405 Cas.

A classical nova 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 close orbit, usually less than 12 hours. As the two stars revolve around each other, the small, dense white dwarf draws hydrogen from its larger, fluffier companion.

This hydrogen ends up in the atmosphere of the smallest star, where it is heated. When hydrogen heats up and becomes dense enough, nuclear fusion is triggered on the white dwarf’s surface, releasing an enormous amount of energy that explosively ejects unburned hydrogen into space.

Unlike a Type Ia supernova, in which the white dwarf explodes, both stars survive and continue their strange relationship, only to explode again another day. The nova itself can continue to glow for a few days or months.

It is not immediately clear which star produced V1405 Cas, but there is a strong candidate: the eclipsing (binary) variable star CzeV3217, which lies at a distance of about 5,500 light-years from the Solar System.

Other observations will help astronomers better understand the nova and confirm that the source is CzeV3217.

nova map(Yuji Nakamura / NAOJ)

Because stellar explosion events like these are so unpredictable, they are not always easy to detect quickly, which is why the discovery of V1405 Cas is quite exciting.

If you want to go out and try to see it for yourself, its coordinates are right ascension 23 24 47.73, declination +61 11 14.8 – not far from Cassiopeia’s star Caph, and an even shorter distance from the B-type star HIP . 115566.

While you’re out there, keep your eyes peeled for anything out of the ordinary …

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