Changes

Willem Janszoon Blaeu (a [[Dutch]] astronomer) was the first person to notice the existence of a new star on August 18, 1600.<ref name=aavso>{{cite web|url=https://www.aavso.org/vsots_pcyg|title=P Cygni

Willem Janszoon Blaeu (a [[Dutch]] astronomer) was the first person to notice the existence of a new star on August 18, 1600.<ref name=aavso>{{cite web|url=https://www.aavso.org/vsots_pcyg|title=P Cygni

|accessdate=December 29, 2021|publisher=aavso.org|author=Matthew Templeton}}</ref> It appears at the third [[star magnitude|magnitude]] for several years before fading to below unaided eye visibility. However it returned to its former brightness in 1626 as well as 1655. Since the 1670s, it has been just about visible to the unaided eye with a magniutde of five, though dark skies are required. The star was named by [[Johann Bayer]] using his standard [[Bayer designation|designation method]].

|accessdate=December 29, 2021|publisher=aavso.org|author=Matthew Templeton}}</ref> It appears at the third [[star magnitude|magnitude]] for several years before fading to below unaided eye visibility. However it returned to its former brightness in 1626 as well as 1655. Since the 1670s, it has been just about visible to the unaided eye with a magnitude of five, though dark skies are required. The star was named by [[Johann Bayer]] using his standard [[Bayer designation|designation method]].

==Properties and Structure==

==Properties and Structure==

P Cygni is situated 10192.60 [[light year]]s from [[Earth]].<ref name=universeguide/> The star has mass between 50-60 solar masses and an extremely hot surface, estimated to have a temperature in excess of 19,400 kelvin.<ref name=illinois/> This high temperature means it radiates somewhere between 500,000 to 900,000 times more energy than the [[Sun]].<ref name=illinois/> This puts its [[absolute magnitude]] at around -8.9, making it one of the brightest stars in the [[Milky Way|galaxy]].<ref>{{cite web|url=http://spider.seds.org/spider/Vars/pCyg.html|title=P Cygni|accessdate=December 29, 2021|publisher=spider.seds.org}}</ref> However our view is slightly dimmed by an intervening cloud of gas and dust. The star is thought to be losing mass in the form of an intense [[stellar wind]] travelling at 300&nbsp;km/s.<ref name=illinois/> It is estimated to loose three hundred thousandths of a [[solar mass]] per year which is three million times more mass than the Sun looses in its own [[Solar wind]]. This complicates the observation of the star as light must pass through this wind on its way to Earth and the particles in the wind interfere with the light.

P Cygni is situated 10192.60 [[light year]]s from [[Earth]].<ref name=universeguide/> The star has mass between 50-60 solar masses and an extremely hot surface, estimated to have a temperature in excess of 19,400 kelvin.<ref name=illinois/> This high temperature means it radiates somewhere between 500,000 to 900,000 times more energy than the [[Sun]].<ref name=illinois/> This puts its [[absolute magnitude]] at around -8.9, making it one of the brightest stars in the [[Milky Way|galaxy]].<ref>{{cite web|url=http://spider.seds.org/spider/Vars/pCyg.html|title=P Cygni|accessdate=December 29, 2021|publisher=spider.seds.org}}</ref> However our view is slightly dimmed by an intervening cloud of gas and dust. The star is thought to be losing mass in the form of an intense [[stellar wind]] traveling at 300&nbsp;km/s.<ref name=illinois/> It is estimated to loose three hundred thousandths of a [[solar mass]] per year, which is three million times more mass than the Sun looses in its own [[Solar wind]]. This complicates the observation of the star as light must pass through this wind on its way to Earth and the particles in the wind interfere with the light.

The star's brightness continues to change, increasing by around 15% per century caused by a reduction of the star's temperature by 6% per century.<ref name=illinois/> Although this means the total energy radiated by the star is reduced, it means less is emitted in the [[ultraviolet]] and instead radiated in the [[visible light|visible]]. There are still small fluctiations up and down, though only at most by 0.2 magnitudes.<ref name=aavso/> These variations can generally occur with a period of 0.156&nbsp;days or 3.75&nbsp;hours, though they can be fairly irregular and are thought to be due to possibly pulsation or flares on the star's surface.<ref name=universeguide/> P Cygni's fluctuation history place it in a very exclusive group of variable stars known as S&nbsp;Doradus star. Other members include [[Eta Carinae]] and [[S Doradus]] in the [[Magellanic Clouds]].

The star's brightness continues to change, increasing by around 15% per century caused by a reduction of the star's temperature by 6% per century.<ref name=illinois/> Although this means the total energy radiated by the star is reduced, it means less is emitted in the [[ultraviolet]] and instead radiated in the [[visible light|visible]]. There are still small fluctuations up and down, though only at most by 0.2 magnitudes.<ref name=aavso/> These variations can generally occur with a period of 0.156&nbsp;days or 3.75&nbsp;hours, though they can be fairly irregular and are thought to be due to possibly pulsation or flares on the star's surface.<ref name=universeguide/> P Cygni's fluctuation history place it in a very exclusive group of variable stars known as S&nbsp;Doradus star. Other members include [[Eta Carinae]] and [[S Doradus]] in the [[Magellanic Clouds]].

==References==

==References==