Revenant of the Swan

 

P Cygni (34 Cygni) and also known as the ' Revenant of the Swan' - Hyper Giant Blue Variable Star in the Constellation Cygnus the Swan - 66mm Altair Starwave refractor with 0.6 x focal reducer and field flattener - Canon 600d DSLR at ISO 800. 3 minute RAW exposures. Credit: Pip Stakkert.

Plate solving. Credit:  Astrometry.net

"This interesting and highly luminous star is located between 5000 and 6000 light years distant and is moving away from us at nearly 9 km/sec. The star has a current magnitude of  4.8  (Absolute Mag -7.9) and may be seen from a dark site with the naked eye. This is incredible considering its vast distance from our Solar System.  P Cygni is extraordinary in many ways! It has a mass 37 times  and radius 76 times that of our Sun. It is 610,000 times more luminous than the Sun and this is the reason it can be seen from such a great distance. It is one of the most luminous stars known in the Milky Way.

The star is an irregular variable and has, over the past 500 years, shown major brightening. In recent times the variability has been less extreme and visual brightening is occurring at 0.15 of a magnitude per century. P Cygni is thought to be burning hydrogen in a shell around its core and if so is moving from hyper giant blue to red super giant stage all part of an evolutionary process as the star moves closer to its likely supernova. The life of a blue hyper giant star is short and violent and measured in millions rather than billions of years when compared with our Sun.

Because of its variability and extreme outbursts in the 17th century, the star was thought to be a recurring nova. Presumably it was named the the 'Revenant of the Swan' because it exhibited a repeated and unexpected return to life after multiple deaths or novae.

P Cygni gives it's name to a type of stellar spectrum that shows both absorption and emission in the profile. The emission line arises from a dense stellar wind near to the star, while the blue shifted absorption lobe is created where the radiation passes through circumstellar material rapidly expanding in the direction of the observer. As the star is quite bright we are hoping to use our transmission grating to obtain a spectrum later in the summer when Cygnus is on the meridian". - Kurt Thrust Director of the Jodrell Plank Observatory.