This isn’t literally a new star, however.<\/p>
‘Nova’ means ‘new star’, and these events are so-called because they amount to the sudden brightening of a previously-dim star in the night sky, to the point that it reaches naked-eye brightness.<\/p>
When a nova occurs, it appears there is now a bright star where no star (or a dim star) was visible before.<\/p>
Historic sightings<\/strong><\/h2>T Coronae Borealis (T CrB) is a recurring nova, which means it predictably appears within set timescales.<\/p>
T CrB, visible in the constellation Corona Borealis, occurs roughly every 80 years, which is useful to know if you’re an astronomer searching for historic records of it in astronomical archives.<\/p>
Bradley E. Schaefer of Louisiana State University believes he’s found evidence that the T Coronae Borealis nova was observed and recorded in 1217 by Abbott Burchard of Ursberg Abbey.<\/p>
The paper stating the find can be found at arxiv.org<\/a> (link at the bottom of this page) and also contains information about a sighting in 1787.<\/p>“T CrB has a recurrence timescale near 80 years,” Schaefer says.<\/p>
“So it is reasonable to look backwards in time for prior eruptions, around 1786, and so on back. I have investigated two long-lost suggestions that T CrB was seen in eruption in the years 1217 and 1787.”<\/p>![\"Chart](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2024\/05\/T-Coronae-Borealis-chart-labelled-1024x752.jpg?fit=800%2C588\")
Chart showing the location in the sky of the T Coronae Borealis nova event. Credit: Pete Lawrence<\/figcaption><\/figure>The 1787 sighting<\/strong><\/h2>In the paper, Schaefer points to a catalogue published in 1789 by the Reverend Francis Wollaston, an astronomer and clergyman.<\/p>
Wollaston’s catalogue, Schaefer says, “reports an astrometric position for a star that is exactly on top of T CrB.”<\/p>
Astrometry is a branch of astronomy concerned with measuring the positions and movements of stars in the sky.<\/p>
Wollaston’s letters reveal that observations were made on at least four occassions with both a large and small telescope, around Christmastime and up to 28 December 1787.<\/p>
“Wollaston’s limiting magnitude<\/a> for his astrometry is near +7.8 mag, so T CrB would have to have been in eruption,” Schaefer says.<\/p>“With other transients strongly rejected, the only way that Wollaston could get the coordinates was to have measured the coordinates of T CrB itself during an eruption.”<\/p>
The 1217 sighting<\/strong><\/h2>![\"Ursberg](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2024\/04\/GettyImages-1002135976-1024x683.jpg?fit=800%2C534\")
Ursberg Abbey in Bavaria, Germany. Did a 13th century abbott observe the T Coronae Borealis event? Credit: Martin Siepmann \/ Getty Images<\/figcaption><\/figure>In the Ursperger Chronicle of 1225, Abbott Burchard of Ursberg Abbey writes about observations made in 1217, which could show that he too witnessed the T Coronae Borealis nova.<\/p>
If true, this would be the oldest recorded observation of the nova, and not dissimilar to records that show the Crab Nebula was observed and recorded by Chinese astronomers in 1054<\/a>.<\/p>Schaefer reveals how Burchard describes a transient star that was visible for many days in autumn of 1217 in the constellation of ‘Ariadne’s Crown’, which is Corona Borealis.<\/p>
“A bright transient lasting for ‘many days’ can only be a nova, a comet, or a supernova,” Schaefer says.<\/p>
“Burchard’s event cannot be a supernova<\/a> or some different nova, due to the lack of any bright remnant.<\/p>“The object cannot be a comet<\/a> because Burchard explicitly called it ‘stella’ (i.e. a point source) instead of any of the several medieval German terms for comet.<\/p>![\"What](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2024\/03\/comet-12p-pons-brooks-april-2024.jpg\")
What Burchard saw couldn’t have been a comet because he described it as a point source of light. Credit: Leonardo Leite<\/figcaption><\/figure>“Further, Burchard labeled it as a ‘wonderful sign’ with very positive connotations, whereas comets are universally regarded as amongst the most evil and dangerous omens in the sky<\/a>.”<\/p>Given what we know about T CrB’s 80-year occurrence, this could be ‘mystery solved’.<\/p>
Was what Abbott Burchard saw in the night sky the nova event we know as T Coronae Borealis?<\/p>
It seems incredibly likely that it was, writes Schaefer.<\/p>
“The reported event is just as expected for a prior eruption of T CrB, and all other possibilities are strongly rejected, so the case for the 1217 eruption of T CrB is strong.”<\/p>
“T CrB has a recurrence timescale near 80 years,” Schaefer says.<\/p>
“So it is reasonable to look backwards in time for prior eruptions, around 1786, and so on back. I have investigated two long-lost suggestions that T CrB was seen in eruption in the years 1217 and 1787.”<\/p> In the paper, Schaefer points to a catalogue published in 1789 by the Reverend Francis Wollaston, an astronomer and clergyman.<\/p> Wollaston’s catalogue, Schaefer says, “reports an astrometric position for a star that is exactly on top of T CrB.”<\/p> Astrometry is a branch of astronomy concerned with measuring the positions and movements of stars in the sky.<\/p> Wollaston’s letters reveal that observations were made on at least four occassions with both a large and small telescope, around Christmastime and up to 28 December 1787.<\/p> “Wollaston’s limiting magnitude<\/a> for his astrometry is near +7.8 mag, so T CrB would have to have been in eruption,” Schaefer says.<\/p> “With other transients strongly rejected, the only way that Wollaston could get the coordinates was to have measured the coordinates of T CrB itself during an eruption.”<\/p> In the Ursperger Chronicle of 1225, Abbott Burchard of Ursberg Abbey writes about observations made in 1217, which could show that he too witnessed the T Coronae Borealis nova.<\/p> If true, this would be the oldest recorded observation of the nova, and not dissimilar to records that show the Crab Nebula was observed and recorded by Chinese astronomers in 1054<\/a>.<\/p> Schaefer reveals how Burchard describes a transient star that was visible for many days in autumn of 1217 in the constellation of ‘Ariadne’s Crown’, which is Corona Borealis.<\/p> “A bright transient lasting for ‘many days’ can only be a nova, a comet, or a supernova,” Schaefer says.<\/p> “Burchard’s event cannot be a supernova<\/a> or some different nova, due to the lack of any bright remnant.<\/p> “The object cannot be a comet<\/a> because Burchard explicitly called it ‘stella’ (i.e. a point source) instead of any of the several medieval German terms for comet.<\/p> “Further, Burchard labeled it as a ‘wonderful sign’ with very positive connotations, whereas comets are universally regarded as amongst the most evil and dangerous omens in the sky<\/a>.”<\/p> Given what we know about T CrB’s 80-year occurrence, this could be ‘mystery solved’.<\/p> Was what Abbott Burchard saw in the night sky the nova event we know as T Coronae Borealis?<\/p> It seems incredibly likely that it was, writes Schaefer.<\/p> “The reported event is just as expected for a prior eruption of T CrB, and all other possibilities are strongly rejected, so the case for the 1217 eruption of T CrB is strong.”<\/p>The 1787 sighting<\/strong><\/h2>
The 1217 sighting<\/strong><\/h2>