New Delhi: Astronomers and stargazers alike are eagerly awaiting the appearance of a “new star” or nova in the night sky. While it won’t dramatically illuminate the heavens, it offers a rare opportunity to witness an event that is usually hard to predict.
The star in question is T Coronae Borealis (T CrB), pronounced “T Cor Bor.” Situated in the constellation of the Northern Crown, this star is typically too faint to be seen. However, approximately every 80 years, T CrB erupts in a spectacular display, shining brightly before fading back into obscurity a few nights later.
About T Coronae Borealis
Located 3,000 light years away, T CrB is a white dwarf, a stellar remnant whose nuclear reactions have ceased, causing it to compress under its own gravity. It has a companion star, a red giant, which it draws gas from. This gas forms an accretion disc around the white dwarf, continuously increasing the pressure and temperature until a thermonuclear reaction ignites on its surface.
When this happens, T CrB shines 1,500 times brighter than usual, making it visible from Earth. This cycle repeats every 80 years or so, with the star expelling the accumulated gas and starting the process anew.
T CrB is the brightest known recurrent nova, a rare class of stars that erupt within a century. Only ten such novae are currently known. Historical records date T CrB’s earliest observed eruption to 1217. The star’s two most recent eruptions occurred in 1866 and 1946, each displaying similar features: a gradual increase in brightness about ten years prior, followed by a brief dip about a year before the eruption.
In 2015, T CrB entered this high state, and the pre-eruption dip was observed in March 2023. This consistency allows astronomers to predict its eruptions with remarkable accuracy.
How to See T CrB
Stargazers should start observing Corona Borealis now to familiarize themselves with its current state. The constellation reaches its best viewing position around 8:30 pm to 9:00 pm local time across Australia and Aotearoa New Zealand. The farther north you are, the higher it will appear in the sky.
When T CrB erupts, it is expected to reach a magnitude of 2.5, making it as bright as Imai (Delta Crucis) in the Southern Cross. This brightness will make it easy to spot, even from urban areas.
Once the nova erupts, its maximum brightness will last only a few hours. Within a week, it will have faded to the point where binoculars will be necessary to see it. The professional astronomical community will likely be alerted to the eruption by amateur astronomers, who regularly monitor stars from their backyards.
The American Association of Variable Star Observing (AAVSO) has logged over 270,000 observations of T CrB, highlighting the crucial role of amateur astronomers in monitoring and tracking such celestial events.
Astronomers hope the nova will erupt as expected before October, as Corona Borealis will then disappear from the Southern Hemisphere’s evening sky. Keep your eyes on the skies for this fleeting but spectacular event.
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