Science of all kinds has long drawn eyes from people in every part of the world. Over the centuries, humanity’s ideas and understanding of the world around us have transformed as new evidence emerges about one hypothesis or another. Still, much is unknown. This year, a rare astronomic event is hoped to help scientists learn more about the universe.
The T Coronae Borealis (T CrB) is a recurrent nova (RNe). It sends out bursts of light approximately every eighty years, and is less than 3,000 light years from Earth, which makes it one of the most famous novae today. It will be visible to the naked eye for a week, reaching a magnitude of two (what does this mean?). Its first documentation was in 1866 by John Birmingham, though there are reports of observations as early as 1217.
But what exactly is a recurrent nova?
A recurrent nova is often confused with a supernova. The latter is a result of the death of a star. This occurs when the object uses up the hydrogen in its core and, unable to sustain its gravitational pull, collapses on itself. Stars of large masses can explode as supernovae, the power of which can influence matter up to several light years away, while smaller ones can become white dwarves.
A recurrent nova, on the other hand, is an explosion of much smaller proportions.
The explanation lies in its set-up. A white dwarf star, which is made up of mostly carbon and oxygen, and a red giant, or a star that has significantly expanded due to its scarcity of remaining hydrogen, orbit each other in a binary system where there are two interacting stars. T CrB’s binary system is a cataclysmic variable. The white dwarf’s accretion disk, which is a formation of an increasing amount of material pulled by gravity around a celestial object, sucks in matter from the red giant, and as the pressure and temperature of the plasma increase – hitting hydrogen’s ignition temperature – it bursts. This is a runaway thermonuclear reaction, or in simpler terms an out-of-control exothermic reaction.
After each explosion, T CrB experiences periods of dimming and brightening every several years. The cause of this is still unknown, but there are suppositions.
Dr. Bell, Pine View’s Physics and Astronomy teacher, speculated, “… that’s usually done because the star itself – the outer envelopes of the star – are trying to reach equilibrium, which means that’s a balance between hydrostatic, gaseous pressure going outward and gravity going inward. … And as it oscillates trying to reach that it gets to a certain point where you get too much stuff and it’s freaking out, by dimming and brightening, and then it’s going to explode… that would be my biggest guess.”
Thrilled about the rare event, Dr. Bell said, “… since I teach an astronomy class, once it’s happening, we’re dropping everything, and we’re going to go outside. We’re going to try to view it the best we can. I know that the class is during the day, so that’s why I’m hoping it’s bright enough to see during the day, but I will definitely be taking pictures, because it’s not going to be back in my lifetime…”
Curiosity piqued, this reporter decided to attend an Astronomy Night in person. The following is a first person account of the evening’s happenings:
The T CrB was not visible during Astronomy Night November 2. In fact, soon after the event started, the sky clouded over and it was impossible to view the stars. I was, however, able to catch a quick glimpse of Saturn and the Andromeda Galaxy.
The campus was uncharacteristically dark, but it felt tranquil and familiar. The serene quiet was interrupted only by the occasional laugh or remark. As I walked towards the middle of the campus, shivering from the chilly weather, I was able to make out some people and a few telescopes standing around.
There were three telescopes provided by the school, and a few personal ones people had brought in. I peered into the one closest to me. A mere dot in the sky to the naked eye, the telescope transformed the glittering object it was centered on into an array of rings around a globe – Saturn. At a closer examination, I could see one of its moons.
Stepping back, I turned to the nearby group of people. With a DwarfLab telescope, we were able to look at the Andromeda Galaxy. A floating disk with a black hole in the middle, it was a cool sight.
At one point, I met senior Jack McCarrick, president of Astronomy Club, who was excited about the T CrB.
“My plans are to attempt to take photos of it through my telescope and do a little bit more research on when it’s predicted to become visible because it isn’t, hasn’t, to my knowledge, it hasn’t become visible yet,” he said.
More people arrived in the next half hour, but by that time little was visible through the heavy clouds. Nevertheless, we had a fun time discussing space terms and concepts. It’s safe to say, I’ll be attending future Astronomy Nights.
Technology has significantly advanced since T CrB’s last explosion in 1946. New space telescopes and other devices will allow astronomers to see the full electromagnetic radiation spectrum of the explosion rather than the 2% previously recorded with simpler technology. This knowledge will be used to scan the universe, searching for other novae and astronomical phenomena.
T CrB should be visible to the naked eye by the end of 2024. It is located in the constellation of the Corona Borealis, more commonly known as the crown. Image from SkyandTelescope.org.