Star of the Month
P Cygni
AKA: 34 Cygni
Position: 20 hrs 17 min 47.2 sec +38 degrees 01 min 59 sec
Due south at 21:40 (BST) on 15 September 2022
P Cygni
Image: Simbad (http://simbad.u-strasbg.fr/simbad/)

P Cygni is the first reasonably bright star below Sadr (Gamma Cygni) and lies to the south-west of the star cluster M29. It had an exciting life in the 17th century and has remained quiet ever since! It was first observed as an apparent nova on 18 August 1600 by a Dutch astronomer Willem Janszoon Blaeur and then given the label P Cygni by Johann Bayer in his famous Uranometria three years later. From being 3rd magnitude it faded by 1626, but flared up again in 1662 and in 1655. The variations in brightness continued until 1715, when P Cygni settled down to become a 5th magnitude star. It has slowly brightened to magnitude 4.8 since then as a result of cooling which has transferred its ultraviolet light into the visible region. A blue supergiant, its behaviour during the 17th century was typical of a class of variable stars called luminous blue variables. It appears that earlier eruptions occurred 900, 2,100 and 20,000 years ago, but it has now been quiet for three centuries. It has been theorised that there was a mass transfer between the blue supergiant and another large companion star but this has not been proved. More exciting, however, the luminous blue variable stage is a sign that the star may undergo a Type IIb supernova which would create a black hole. However at the great distance of 5,000 light years away the resulting fireworks may be less impressive than we would like! 
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