This summer, professional and amateur astronomers around the world will set their sights on a small constellation in the night sky. However, they will not be the 7 stars of the Corona Borealisthe “Crown of the North”, to capture their attention, but rather a point dark among these where one is imminent newso bright that it is visible to the naked eye from Earth.
A unique event
“It’s a once-in-a-lifetime event that will create many new astronomers, giving young people a cosmic event they can observe for themselves, ask questions and collect data,” he has declared Rebekah Hounsell, from NASA’s Goddard Space Flight Center. “It will be fuel for the next generation of scientists“.
The binary system T Coronae Borealis
T Coronae Borealisknown by astronomers simply as “T CrB”, is a binary system located in the Crown Boreal, about 3 thousand light years from Earth. The system is composed of a white dwarf, an Earth-sized remnant of a star with a mass comparable to that of our Sun, and an ancient red giant that is slowly being stripped of its hydrogen by the white dwarf’s powerful gravitational pull.
The red giant’s hydrogen accumulates on the surface of the white dwarf, causing an increase in pressure and heat. Ultimately, this triggers athermonuclear explosion big enough to expel the accumulated material. For T CrB, this event appears to repeat, on average, every 80 years.
Nova and supernova
Hounsell highlighted that a new should not be confused with one supernovaexplosion the final And titanic which destroys some dying stars. In an event of newthe white dwarf remains intact, sending the accumulated material into Space with a dazzling flash. This cycle can repeat itself over time, a process that can continue for tens or hundreds of thousands of years.
The wait for the big event
The first recorded observation of the T CrB nova dates back more than 800 years agoin the autumn of 1217, when a man named Burchard, abbot of Ursberg, Germany, noted “a faint star that for a time shone with great light“. The T CrB nova was last seen from Earth in 1946. Its behavior over the past 10 years appears very similar to that observed in the run-up to the 1946 eruption. If the pattern continues, some researchers say the nova could occur by September 2024.
What to expect and how to observe the cosmic explosion
Skywatchers must look for the Crown Boreal, a horseshoe curve of stars west of the constellation Hercules, visible on clear nights. It can be found by drawing a straight line between the 2 brightest stars in the Northern Hemisphere, Arcturus and Vega, which will take observers to Hercules and the Corona Borealis. The cosmic explosion will be brief – it will be visible to the naked eye for less than a week – but Hounsell believes it will be a remarkable sight.
A coordinated scientific approach
Elizabeth Hays, head of Goddard’s astroparticle physics laboratory, agrees. Part of the fun in preparing to observe the event is seeing the enthusiasm among astronomy enthusiasts, whose interest in extreme space phenomena has supported a long and rewarding collaboration with NASA.
“Citizen scientists and space enthusiasts are always looking for those strong, bright signals that identify nova events and other phenomena,” Hays explained. “Using social media and email, they send instant alerts. We are counting on that global interaction again this time with T CrB“.
The Fermi space telescope from NASA, which has been observing gamma rays from low Earth orbit since 2008, is poised to observe T CrB when the nova eruption is detected, along with other space missions such as James Webb Space Telescopethe observatory Neil Gehrels Swift, IXPE (Imaging X-ray Polarimetry Explorer), NuSTAR (Nuclear Spectroscopic Telescope Array), NICER (Neutron star Interior Composition Explorer) e INTEGRAL of the European Space Agency. Numerous ground-based radio telescopes and optical instruments, including the Very Large Array from the National Radio Astronomy Observatory in New Mexico, will participate in the observation. Collectively, the various telescopes and instruments will capture data across the visible and non-visible light spectrum.
“We will observe the nova event at its peak and during its decline, as the visible energy of the explosion fades,” explained Hounsell. “However, it is equally important to obtain data during the initial surge phase towards the eruption, so the data collected by those eager citizen scientists who are now searching for the nova will contribute greatly to our results“.
A rare research opportunity
For astrophysics researchers, this promises a rare opportunity to shed new light on the structure and dynamics of explosions stellar recurring like this. “Typically, nova events are so faint and distant that it is difficult to clearly identify where the eruptive energy is concentrated,” Hays emphasized. “This one will be really close, with a lot of eyes on it, studying the various wavelengths, and we hope to get data to start to unravel the structure and the specific processes involved. We can’t wait to get the full picture of what’s happening“.
Some of those eyes will be completely new. Gamma-ray observatories did not exist the last time T CrB exploded in 1946, and the polarization capability of IXPE, which identifies the organization and alignment of electromagnetic waves to determine the structure and internal processes of high-energy phenomena energy, it is a completely new tool in X-ray astronomy. By combining their data, we will be able to gain an unprecedented understanding of the life cycles of binary systems and the powerful stellar processes that power them.
Cosmic explosion, an event not to be missed
Is there a chance that September will pass without the long-awaited cosmic explosion of T CrB? Experts agree that there are no guarantees, but hope is high. “Recurring novae are unpredictable and contradictory,” said Koji Mukai, a research astrophysicist at Goddard. “When you think they can’t follow a certain pattern, they do – and as soon as you start counting on them repeating the same pattern, they deviate completely. We’ll see how T CrB will behave“.
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