In the coming nights, a rare event will occur in the night sky as a “new star” or nova appears. Although it won’t be a spectacular sight, it presents a unique opportunity to witness this unpredictable phenomenon.
The nova in question is T Coronae Borealis (T CrB), located in the constellation of the northern crown. It can be seen in the Northern Hemisphere and parts of Australia and New Zealand over the next few months.
Normally, T CrB is too faint to be visible, as it is located 3,000 light years away. However, approximately every 80 years, it undergoes a bright eruption.
This eruption causes a sudden appearance of what seems like a new star, but it quickly fades and disappears within a few nights.
During its prime, stars are fueled by nuclear fusion reactions in their cores, which keep them stable and shining for billions of years. However, T CrB is now a white dwarf, a stellar remnant that has exhausted its internal nuclear fire. Gravity has compressed the dead star, making it about the size of Earth but 300,000 times more massive.
T CrB has a companion star, a red giant that has expanded in old age. The white dwarf absorbs the gas from the red giant, forming an accretion disc around itself. The accumulation of matter increases pressure and temperature, leading to an extreme thermonuclear reaction on the surface of the white dwarf.
This reaction causes T CrB to shine 1,500 times brighter than usual, making it visible in the night sky for a brief period. After the eruption, the star expels the gas, and the cycle begins again.
T CrB belongs to a rare class of recurrent novae that repeat within a hundred years. Astronomers have been able to predict its eruptions with precision based on its past patterns. The star’s two most recent eruptions occurred in 1866 and 1946, showing the same features. In 2015, T CrB entered its high state, and a pre-eruption dip was observed in March 2023, indicating that an eruption is imminent.
To observe the nova, stargazers are advised to familiarize themselves with the current appearance of Corona Borealis, as it will enhance the impact of the “new” star. The best time to observe Corona Borealis is around 8:30 pm to 9 pm local time in Australia and New Zealand. The higher the latitude, the higher the constellation will be in the sky.
The nova is expected to have a reasonable brightness, similar to the fourth brightest star in the Southern Cross. It will be visible even from city locations if one knows where to look.
The maximum brightness of the nova will only last a few hours, and within a week, it will fade, requiring binoculars to see it. Amateur astronomers are likely to be the first to detect the eruption and alert the professional community. These dedicated individuals play a crucial role in monitoring stars and filling gaps in night sky observations.
The hope is that the eruption will occur before October, as Corona Borealis will no longer be visible in the Southern Hemisphere after that time.
