11-05-2025
This star erupts every 80 years. This Cape Cod astronomer wants to be first to see it.
From his home in West Dennis, amateur astronomer Gary Walker has his sights set on a cosmic prize: being the first person to spot the next nova from T Coronae Borealis, a stellar eruption that could temporarily add a new bright star to the night sky between now and September.
Boosting his chances are the two remote telescopes he regularly uses to scan the sky — one in New Mexico, the other in Spain — both currently programmed to keep nightly watch on the binary system 3,000 light-years away.
He's monitored T Coronae for the past few years.
"It's an unusual object that has a faint magnitude in the sky, but every 80 years it has an outburst. It will become visible to the naked eye, possibly even in downtown Boston or New York City," he said.
The last time it happened was in 1946, Walker said, "so it would be very interesting to be the first person since to see it in outburst. Many other amateur astronomers are also diligently watching it hoping to capture the honor."
When the nova does occur, T Coronae will brighten over a period of eight hours to a couple of days, then fade within just a few days.
"You have to just be lucky enough to have it happen while you're watching," Walker said.
T Coronae, about 3,000 light-years away in the constellation Corona Borealis, was expected to go nova in 2024. That didn't happen, but NASA recently reignited anticipation after detecting activity changes that could signal an eruption sooner than later.
Walker said the system often flickers and dims, keeping everyone guessing. But, like NASA observers, he also recently noticed unusual activity that's got him and others closer to the edges of their seats.
'I observed it got fainter more than it typically does,' he said, though it's difficult to know if that's meaningful.
Astronomers last recorded an eruption from this system in 1946, with previous outbursts documented in 1866 and 1787. The oldest known record dates to 1217.
Walker got hooked on skygazing at 14 after glimpsing Saturn through a neighbor's telescope. He later spent 17 years as a telescope engineer at Maria Mitchell Observatory on Nantucket and now splits his observing time on his two remote scopes with fellow skywatchers.
"I get between two and four hours a night on each telescope," he said. "The operation is controlled via software and you tell it which object you want to observe, where and when."
Walker and other observers feed their data into the American Association of Variable Star Observers, where both professionals and amateurs track subtle changes in brightness that could signal an oncoming nova.
T Coronae consists of two stars — a white dwarf and a red giant — engaged in a slow-motion exchange of mass.
A nova happens when a white dwarf siphons hydrogen gas from a nearby, larger companion — typically a red giant or a Sun-like star.
As the gas builds up on the white dwarf's surface, the pressure and heat eventually trigger a thermonuclear explosion, causing the star to brighten dramatically for a short time. The white dwarf survives the blast, and the process of gas accumulation and eruption can repeat.
'The correct term is a recurrent nova,' Walker said.
That's different from a supernova, he added, 'which is a star that's burned through all of its hydrogen and helium' and dies in a final, catastrophic explosion.
Novae only happen in binary or multiple-star systems where a white dwarf closely orbits a larger companion. Eventually, the T Coronae red giant will shed its outer layers and become a white dwarf too — likely ending the nova cycle. It is not massive enough ever to burst as a supernova.
T Coronae Borealis usually shines at a faint magnitude of 5.5 — just on the edge of naked-eye visibility under perfect dark-sky conditions. It's 17.6 quadrillion miles from Earth, so far that NASA's fastest spacecraft, the Parker Solar Probe, would take 4.7 million years to reach it.
When T Coronae erupts, astronomers expect it to reach at least magnitude 2. For context, on the astronomical magnitude scale — where lower numbers indicate brighter objects — Venus shines at about -4.5, Jupiter at -2, Saturn around +0.5, and Mars typically near +1.5.
A magnitude 2 nova would make T Coronae Borealis one of the brighter stars visible at night. "It may even be visible in telescopes in the daytime if you know exactly where to look," Walker said.
If the white dwarf has pulled in more material than usual, its nova will be more luminous.
To spot the nova, start by locating the constellation Corona Borealis.
"Right now, it appears high in the sky after midnight," Walker said. "Then all summer long it'll become visible earlier and earlier. In the fall it'll be visible somewhat west of overhead."
The nova will appear between two bright stars: Arcturus in the Boötes constellation and Vega in Lyra. NASA suggests using the end of the Big Dipper's handle as a guide — it points in the general direction of Corona Borealis.
Astronomers recommend getting familiar with the constellation's shape and the star's usual faint location ahead of time. That way, when it does erupt, the appearance of a sudden 'new star' will be easier to notice.
Heather McCarron writes about climate change, environment, energy, science and the natural world, in addition to news and features in Barnstable and Brewster. Reach her at hmccarron@
Thanks to our subscribers, who help make this coverage possible. If you are not a subscriber, please consider supporting quality local journalism with a Cape Cod Times subscription. Here are our subscription plans.
This article originally appeared on Cape Cod Times: Cape Cod astronomer tracks star that could soon go nova
