Saturday, 26 September 2020
Epsilon Auriga is a noted eclipsing binary, it is the star that forms the apex of the small triangle of stars that form the Kids just below Capella the brightest star in Auriga. Capella is known as the She Goat Star so wherever Capella goes the kids will always follow.
Epsilon or to give its proper name Almaaz which means the ‘Billy Goat’, is a F0 supergiant with a huge companion of some unknown type. The eclipse is massive and about every 27 years Almaaz fades from magnitude 2.9 to 3.8 it stays like this for between 640-730 days.
The first recorded fading of the star was in 1821, however it was only in 1912 that astronomers realised how extraordinary the eclipse is.
The nature of the Almaaz system is still a mystery to astronomers, one suggestions is that the companion star might be an enormous yellow supergiant star. Astronomers are not even sure how far away Almaaz is with estimates from 1,000 to 1,350 light years away.
The last eclipse was in 2009-2011 with the next eclipse predicted to occur around the year 2037.
Friday, 25 September 2020
Thursday, 24 September 2020
Alpha Ursa Majoris or Dubhe is the northern most of the two pointers that indicate how to find the North Star. Although designated alpha it is actually the second brightness star in the constellation. The name Dubhe means the ‘Bear’ in Arabic.
Dubhe has a magnitude of 1.8 and is a K0 orange giants tar with a temperature of around 4,600 degrees lying at a distance of 123 light years. Dubhe is not part of the Ursa Major Moving Group of stars which consist of 14 stars of which 13 are located in Ursa Major.
Dubhe has a close companion star which orbits around it every 44 years but its a very difficult star to see without a large telescope. Dubhe has been suspected of being a variable star. In 1867 the German astronomer H J Klein thought the star showed changes in colour from reddish to yellow. In 1881 it was suggested that the star varied in brightness with a period of 54 days. Today astronomers believe that any light variations are very small indeed.
An Observatory for Stockport
On the 24th September 1860 the foundation stone for an observatory at Vernon Park, Stockport was laid. The observatory was to be designed on the English period of Gothic style.
The observatory will be divided into 8 chambers the top storey will be used for astronomical purposes.
The building will be made of the best hard red and white bricks with Hollington stone for the windows and dressings. The staircase will be of hard Yorkshire stone. The top of the tower will be open but protected by a light ornamental iron railing. The height of the building will be 160 feet and the cost will be £1,000.
Sadly the funds for the tower were not raised so this potentially fine observatory for Stockport was never built.
Wednesday, 23 September 2020
On December 13th 1934 J P M Prentice an English astronomer discovered a nova in the constellation of Hercules. It would brighten until on December 22nd it reached a maximum brightness of magnitude 1.5 making it the brightest star in the constellation of Hercules.
The word nova comes from the Latin for new, in the middle ages when astronomers saw a new star they thought it was a star being born and called it a nova, we still use this term today.
We now know that a nova is a binary system there are two stars one a small hot massive star the other a larger but less massive star. The small star pulls gas off from its companion and this cool gas forms a disc around the smaller hotter star, eventually this gas will cascade down onto the hotter star. As this gas is cooler it makes the hotter star ‘sizzle’ and it will throw off a shell of gas into space.
This gas which represents only about 0.1% of the mass of star but causes a faint star which normally cannot be seen without a large telescope to appear visible to the naked eye. Of course not all nova become bright enough to be seen with the naked eye.
DQ Hercules appeared at a time when astronomers were trying to work out the difference between ordinary nova and nova that appeared very bright, these would of course be termed Supernova and this term would first be used by the Swiss astronomer Fritz Zwicky at around this time.
The Cooke 25 inch Telescope and Capella
In 1870 the Newall telescope which had beem made by Thomas Cooke and Sons of York and had a lens 25 inches across was installed in the observatory of Robert Newall in Gateshead. Following the death of Robert Newall in 1889 the telescope was sent to Cambridge and was used by Hugh Newall the youngest son of Robert.
In 1899 using the 25 inch Hugh Newall with a 4 prism spectroscope observed that the star Capella the brightest star in the constellation of Auriga the Charioteer was a binary star.
In America during 1899 Prof William Wallace Campbell at Lick Observatory also noted that Capella was a double, this was based on photographs taken between 1896-1897.