This year is the 200th anniversary of the death of Edward Pigott one of the ‘Fathers of Variable Star Astronomy’ this was a title I gave him and the deaf astronomer John Goodricke who between 1781-1786 would make incredible advances in the discovery and study of the branch of astronomy we know of today as variable stars.
Pigott was born in
Whitton, west London in 1753 and died on June 27th, 1825. His life would make
an incredible soap opera story, but much more of that later.
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| Edward Pigott |
Here is another of a series of highlights from his
incredible career.
The year 1795 was a busy one for Edward Pigott and his
search for variable stars. He had already identified the star R Corona Borealis
to be a variable star and now he was about to discover another one. R Scutum.
In the 18th century at the time of Edward Pigott
this star was in the constellation known to him as Sobieski ‘s Shield. This
constellation is a modern constellation compared to the ancient Greek ones. It
was Johannes Hevelius the Polish astronomer who created the constellation in
1684 to commemorate the victory of King John Sobieski over the Ottoman Empire
at the Battle of Vienna in 1683. Today the constellation is simply known as
Scutum the Shield.
Pigott said that there are very few stars in the
constellation and that this star was not recorded by Hevelius. This would
suggest that Hevelius created the constellation the star was at its faintest
and therefore not seen by Hevelius.
Looking at his notes he first saw R Scutum in September 1795
and quickly realised that it changed in brightness. He believed it had a period
of around 63 days, a period he would have worked out towards the end of 1795.
and varied in brightness between magnitude 5 and magnitude 7.8. Unlike R CrB
which faded from view when at its faintest Pigott could follow this star
through its cycle of light changes.
Pigott would observe R Scutum through until October 1801. I
assume that because he could follow the complete cycle it was easier to study
than R CrB which was far more irregular in nature and at its faintest
disappeared.
Today astronomers recognise R Scutum as a RV Taurus type of variable star. Strangely though R Scutum is brighter than the named star of this type. These stars vary in a regular and irregular way and are not very well understood. Astronomers today are still trying to work out makes these stars tick.
Astronomers today know that R Scutum varies between
magnitude 4.2 to 8.6 so Pigott’s estimate of magnitude 5 and 7.8 was close to
modern day estimates. However, one area that Pigott got wrong was the length of
time it took the star to vary in brightness, he thought it was 63 days we know
today it is around 146 days
www.theramblingastronomer.co.uk
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