July 2024
The Backyard Astronomer
Adam England

T Corona Borealis: The Blaze Star

The ancients observed many of the same ‘naked-eye’ phenomena that we also see today, and although their understanding of these astronomical events was limited, they knew something unique was occurring. Episodes like lunar or solar eclipses or the passing of a comet could be seen as messages from the heavens heralding great events, or as omens of destruction. We know now that these astronomical events have no impact on the sociopolitical landscape, nor do the stars you’re born under determine specific personality traits, but it was by tracking these happenings that patterns began to emerge.

Meteor showers were among the first sights to be known as regularly occurring. As humans worldwide saw these recurring fireballs seasonally and in specific parts of the sky, we refer to most meteor showers based on the constellation from which they appear to stem. Similarly, astronomers from many cultures documented a “guest star” that appeared on July 10, 1054 and continued to shine bright through April 1056. Compiling astronomical records from Chinese, Islamic, European, and Native American cultures led us to the Crab Nebula, giving us nearly a thousand years of recorded history of this distinctive event.

Other novae have been registered in the same location many times over the centuries. Where a supernova registers the end of a star’s life as it bursts into a nebula, a recurrent nova continues to feed off a neighboring star again and again, establishing a pattern of brightening and dimming. Enter T Corona Borealis, stage left.

The small constellation Corona Borealis — The Northern Crown — is essentially seven stars in a semicircular arc, filling the space between Hercules and Boötes. This void contains just a few faint galaxies that are difficult for even seasoned backyard astronomers to view, but one of the stars holds a secret.

Blaze Star location at red circle above

Every 78 years T Corona Borealis, aka the Blaze Star, suddenly brightens from a dim magnitude 10 to a peak of near magnitude 2. The smaller, hotter white dwarf continuously sucks the outer layers off the larger, cooler red giant, separated by only half the distance from Earth to the sun, forming a large accretion disk surrounding the white dwarf, all hidden inside a thick cloud of gas and dust. After slowly devouring its larger neighbor for three-quarters of a century, the white dwarf gets stellar indigestion and ejects huge volumes of material into the cosmos, brightening tremendously as it does. Astronomers documented this recurrent brightening in 1866 and 1946, with historical records dating as far back as 1217 recording a similar event in the same part of the sky, likely to be the Blaze Star. We can’t predict exactly when this will happen, so keep your eyes to the Northern Crown and Blaze Star this summer for an extra-special surprise.

If you would like to learn more about the sky, telescopes, or socialize with other amateur astronomers, visit us at prescottastronomyclub.org or Facebook @PrescottAstronomyClub to find the next star party, Star Talk, or event.

Adam England is the owner of Manzanita Financial and moonlights as an amateur astronomer, writer, and interplanetary conquest consultant. Follow his rants and exploits on Twitter @AZSalesman or at Facebook.com/insuredbyadam.