The Rambling Astronomer

The Moon its our nearest neighbour in space and the only place apart from the Earth where people have walked upon. This is the Moon's 4.5 billion year story.

If you explore the night sky using a star atlas such as Sky Atlas 2000 don't be surprised if you come across some strange results when looking at stars that are and are not given Flamsteed numbers.

T Coronae Borealis is also know as the Blaze Star, its a nova which erupted on May 12th 1866 eventually reaching magnitude 2.2 it then took only 8 days to fade below naked eye visibility. The star then stunned astronomers when on February 1946 T CrB went novae again reaching magnitude 3.0. It is what astronomers call a recurrent nova.

September 10th 1784 was a night to remember in the city of York because Beta Lyrae was found to be variable by the deaf astronomer John Goodricke who was observing from the Treasurer’s House in the city. It was the same night that Edward Pigott also observing from the city of York on that same night discovered that eta Aquila was also a variable star. When I was Curator of Astronomy at the Yorkshire Museum in York I christened these two the ‘Fathers of Variable Star Astronomy’.

Rho was first described as a variable star in 1901 when until 1946 it varied in brightness between 4.1 to 4.5 then unexpectedly in that year it faded to magnitude 6.0 it then returned to about magnitude 4.5. The same thing happened in 2000 and 2001. Checking back even further the same thing was recorded in 1893. There appears to be a cycle of events every 50 or so years. So what is going on here?

Eta is among the most distant stars that we can see with the naked eye. It lies at a distance of around 7,500 light years. There is evidence to suggest that a 4th magnitude star located in the position of eta was recorded by the Dutch astronomer Pieter Keyser. In 1603 Johann Bayer who labelled the 24 brightest stars in each constellation with a Greek letter labelled this star as eta Argus. We must remember that the constellation of Carina was one part of the giant constellation Argo Navis.

One of the most famous and most interesting stars in the sky. It is ranked as the 10th brightest star in the sky, but although being labelled as alpha it is usually slightly below beta or Rigel in brightness. It is a variable star normally varying between 0.3 to 0.8, its a semi regular variable star with a variable period of between 400- 1,000 days. However during during 2019 and 2020 it became much fainter than normal and caused astronomers many headaches.

Most variable stars are faint and either difficult to see with the naked eye or with binoculars and requires telescopes to see those stars. However one notable exception to this idea is gamma Cassiopeia. The star does not have a recognised name and is simply referred to by its Greek letter notation.

I have mentioned in the past couple of podcasts how important the Goodricke and Pigott era for variable star astronomy was. After Goodricke’s death Pigott was distraught and moved from York to the city of bath. But he did not give up his astronomy work.
In 1795 while observing the small constellation of Corona Borealis he discovered yet another new class of variable star. This would be the prototype example of the R Corona Borealis type stars.

Possibly the most famous and arguably one of the most important of all the types of variable stars are the Cepheids. The first to be discovered, delta Cephei was from York in 1784, and you have probably all ready guessed it was discovered by John Goodricke.