Monday, 30 November 2020

Astrognome 100 Great Stars No 87 Theta 1 Orionis

 

Theta 1 Orionis

Centred in Orion’s Sword around 1400 light years away, the Orion Nebula, a classic diffuse nebula 20 light years across, the nebula is also known as M42. This is a stellar nursery where stars are being created. It is energised by a quartet of stars that is collectively called Theta 1 Orionis or the Trapezium. These hot O and B class stars were created only a few 100 thousand years old.



The Trapezium stars are lettered from west to east A, B, C, and D. As a unit they generate 250,000 solar luminosities and are at the pinnacle of one of the densest star clusters, the Orion Molecular Cloud in the Milky Way.


The hottest of the 4 stars is Theta 1 C with a spectral class of O6 and a surface temperature of around 40,000 degrees and is the hottest star that can be seen with the naked eye. Although the quartet is so close that optical aid is required to see all 4 stars. Theta 1 is bound to become a supernova in the future as will many of the other stars in this nebula.








Henry Savile and the Savilian Professor of Astronomy

 

Henry Savile 1549-1622

One of the most prestigious positions in astronomy today is the Savilian Professor of Astronomy at the University of Oxford. You have probably guessed it was a Yorkshire man who established that position, Sir Henry Savile was born on November 30th 1549  and died on February 19th 1622 was born at Bradley, near Halifax.



He was an English scholar, Warden of Merton College, Oxford, and Provost or chairman of the governing body of Eton College. He was also a Member of the Parliament. In 1583 Henry Savile together with John Chamber and Thomas Digges were asked to sit on a commission to consider whether England should adopt the Gregorian calendar, as proposed by John Dee.

The Gregorian calendar had been introduced into catholic Europe in 1582 when ten days were lost but in protestant countries such as Britain it would not adopted until 1752. This meant that when the Gregorian calendar was eventually introduced in Britain and its colonies much later than most of Europe the error in days had increased so much that to replace the Julian calendar eleven days were lost. If you was living anywhere in Britain in 1752 Wednesday September 2nd was followed by Thursday 14th September!

In 1604 Savile was knighted and in 1619 he established at the university of Oxford the position of Savilian Professor of Astronomy. It has to be filled by a scholar of distinction, with an outstanding teaching, research and publication record.

Sunday, 29 November 2020

Cooke for sale in Manchester

 

Cooke for sale in Manchester

I came across an advert for a Cooke telescope for sale in Manchester

In March 1903 a Thomas Cooke telescope was being offered for sale by R. Holling-Drake of Edgerley House, Stockport.

It was described as a magnificent telescope 6 feet long with a 4.5 inch object Glass or lens. It was equatorially mounted and was equal to new.

I have no idea how much the telescope was valued at or whether the individual was known to astronomers in Manchester or if Edgerley House still survives.

Astrognome 100 Great Stars No 86 T Tauri

 

T Tauri

T Tauri was first identified as a variable star in 1852 but it was in 1945 that Alfred Joy at the Mount Wilson Observatory established as a new class of variable stars, the T Tauri stars. They had irregular light variations of about 3 magnitudes, their spectral type was type F5-G5 with emission lines resembling the solar chromosphere, they had low luminosity and were associated with dark or light nebulae.


Since 1945 astronomers have learnt more about the T Tauri stars but the basic principles laid out in 1945 still hold sway. T Tauri is the prototype for this youthful type of star. These are stars are around 10 million years old and during the next 100 million years they will begin their journey on the main sequence of stars.


The main sequence is a section of the Hertzsprung Diagram and is a chart that astronomers use to plot the time line of stars. The vast majority of stars will follow the main sequence during the time line. T Tauri stars can be described as pre main sequence stars.



Saturday, 28 November 2020

Astrognome 100 Great Stars No 85 T Corona Borealis

 

T Corona Borealis

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. There was a small number of other stars that had been observed to go novae more than once but they had not reached naked eye visibility.



Novae are binary systems with a small hot star and a large cooler star. The hotter star pulls some of the cooler gas from its companion, this gas then falls onto the surface of the hot star which then throws of a small shell of gas into space. We see this light and in the medieval period these were referred to as Nova. The word nova is Latin for new. Today we know that novae are not new stars.

T Corona Borealis is still called the ‘Blaze Star’ although over the pas 25 years astronomers have discovered that all nova are recurrent novae just as T Corona Borealis is. There periods can be measured over decades or centuries.

The Aurora of November 27th 1872 seen from Liverpool

 

The Aurora of November 27th 1872 seen from Liverpool

The aurora display of November 27th 1872 appears not to attract that much attention because it occurred on the same night that as the spectacular Andromedid meteor shower, which was the remains of comet Biela burning up in the Earth’s atmosphere.



Samuel Barber of Liverpool commented about the aurora and described it as merely a hazy or diffused cloudy light, devoid of both colouring and symmetry of form. He went on to say that he had observed this variety of aurora on several occasions but it appears to attract few observers.

Friday, 27 November 2020

Thomas Cook Can Vote

 

Thomas Cook Can Vote

Thomas Cook optician of Stonegate in York was objected to being able to vote in the general election of 1837 by a Mr Graham because he believed that Mr Cook was not a £10 Freeholder. At this time unless you owned a freehold property to the value of £10 you were unable to vote.



However on checking it was found that Mr Cook had a previous rating that showed he was a £10 Free holder owning his opticians shop in Stonegate and was therefore allowed to vote.

The 1837 election was won by the Viscount Melbourne. I do not know which way Thomas Cook voted. Also note that his name is spelled without an ‘e’, he went from Thomas Cook to Thomas Cooke sometime in the early 1840s.

Astrognome 100 Great Stars No 84 Supernova 1987A

 

Supernova 1987A

High on top of a Chilean mountain in February 1987 Ian Shelton was developing the last of the photographs he had taken of one of our companion galaxies, the Large Magellanic Cloud when he noticed something was ‘wrong’. There was a brilliant new star where none had been before. The same thing thing had seen the day before by Robert McNaught in Australia. Astronomers were looking at the first naked eye supernova since Kepler’s Star of 1604.


This supernova would be known as SN 1987A would eventually reach around magnitude 3.0 in May of 1987. This gave astronomers their first chance to study a relatively close super nova, the Large Magellanic Cloud is only around 163,000 light years away. It was a type II supernova whereby the star imploded upon itself and by studying it many of the theories that astronomers had about supernovae were proved to be correct.



A bright ring of material has been observed by astronomers over the past 30 or so years to move away from where the star was located. It was always assumed that a neutron star would be formed by this kind of supernova explosion and in 2019 astronomers found that neutron star.



It was later discovered by astronomers that the star that had gone supernova was Sanduleak -69 202 a blue supergiant.

Thursday, 26 November 2020

Astrognome 100 Great Stars No 83 SS Cygni

 

SS Cygni

Next to the massive novae like stars such as Nova Hercules 1934, the dwarf nova such as SS Cygni in the constellation of Cygnus the Swan resemble a string of Chinese fire crackers. SS Cygni is the prototype of these dwarf novae. SS Cygni stars produce scaled down versions of classical novae.



SS Cygni is one of the best observed of these star and around every 50 days it will increase in brightness from magnitude 15 to 8. This rise in magnitude typically take between 1 to 2 days. The main difference between classical and dwarf novae is that a classical novae is made up with a binary system consisting of a small white dwarf and a larger giant star, while the SS Cygni or dwarf novae system consists of a white dwarf and a red dwarf.


Thomas Cooke's Old Steam Boat?

 

Thomas Cooke’s Old Steam Boat ?

I know that Cookes started making a small number of steam boats and fishing vessels from 1876 but I was fascinated to come across details of Cooke’s in 1872 offering a small steam launch for sale, it had been newly fitted up and was in perfect order. It was 29 feet long with a beam of 6 feet.

Could this have been the boat that Thomas Cooke used in 1867 to go up and down the river Ouse in this little boat using his steam engine?

Thomas Cooke not only made scientific instruments in York he also built a small number of steam cars in 1866, these he used to visit among other people his brother Barnard who lived in Hull.



However due the Road Act any vehicle that was not pulled by a horse, i.e. ‘a horseless carriage’ had to have a man with a red flag walk in front of the vehicle. As a man walks at a speed of around 4 miles per hour and Cooke’s steam car travelled at around 15 miles per hour this was clearly a dangerous thing to do.

It is believed Cooke built 4 or possibly 6 of these steam cars, none survive today or at least as far as I know none survive. The picture here is the only one to show one of these steam cars. On being told that the vehicles were illegal Cooke simply put one of his steam engines into a small boat and took it on the river Ouse in York where no one would tell him how fast he could travel.



Wednesday, 25 November 2020

Astrognome 100 Great Stars No 82 Spica

 

Spica

One of the brightest stars in the spring sky, Spica is in fact the 16th brightest star in the sky. It is the brightest star in the constellation of Virgo the Virgin, which in fact is the largest of the zodiacal constellations. Sadly from Britain Spica is always seen low down in the sky. The name Spica means Ear of Wheat.



To find Spica draw a line from the three stars that form the handle of the Plough follow the curve round and down you will reach the bright star Arcturus in Bootes, then continue the curve until you reach Spica.

Spica shines with a magnitude of 1.0 and is a B class star meaning that it is hotter than the Sun. Spica lies at a distance of about 250 light years. It was discovered in 1899 that the star is a double. As Spica is in the zodiac planets can pass in front of it. The last time a planet passed in front of or occulted Spica was by Venus in 1783.



Spica can be seen on the flag of Brazil, there are 27 stars which represent the night sky on the night of independence. Spica is the only star which is above the white band. It symbolises the only part of the territory above the equator.


Snowballing and the Cooke Works

 

Snowballing and the Cooke Works

In early December 1882, two youths employed at the Thomas Cooke, Buckingham Works, Bishophill, York were summoned for snowballing near the works. It was shown that two residents in the vicinity were compelled to put their shutters in lest their windows should be broken.

Mr Haley stated that he had had numerous complaints respecting snowballing. Mr Ditmas who appeared for the boys submitted that the defendants not having been previously warned might with justice be discharged.

Mr Rowntree said that snowballing could not be considered a privileged. The youths were find 1 shilling each.


Tuesday, 24 November 2020

Will Hay, Nova Puppis and a Cooke

 

Will Hay, Nova Puppis 1942 plus a Cooke

Will Hay is best remembered as a comedian of the stage and films in the 1930s and 1940s. He was also a very competent astronomer who discovered a white spot on Saturn in 1933 using a 6 inch Cooke telescope. He also observed Nova Puppis 1942 with a Cooke this time a smaller 3.5 inch telescope.



Observing from London early in the morning of November 24th 1942 and using his 3.5 inch Cooke he saw the nova. He had seen it a few days earlier on November 14th as a naked eye object of around magnitude 3.5. By November 24th it had faded and a telescope was needed to see it.

It was very close to the horizon and he estimated the brightness of the nova as between magnitude 4 and 5 but as he commented being so close to the horizon it is difficult to estimate the brightness of a star so low in the sky due to the amount of atmosphere the light has to pass through.

Will Hay was also struck by the red colour of the nova. He checked other stars nearby of about the same brightness and they appeared to be their normal colours suggesting that the redness was in the nova itself.


Nova Puppis was discovered by Bernhard Dawson at the La Plata Observatory in Argentina on November 8th 1942. It reached a maximum magnitude of 0.3 on November 10th 1942.



Astrognome 100 Great Stars No 81, 61 Cygni

 

61 Cygni

Although it appears that the stars stay in one place in the sky and do not move some stars do show tiny amounts of movement. Astronomers had for some time noticed these tiny movements but until 1838 no one had been able to measure them. Then in 1838 the German astronomer Freidrich Bessel observed 61 Cygni in the constellation of Cygnus the Swan.



61 Cygni was the first star to have its distance measured by a technique known as the Stellar Parallax or its movement against the background stars. A magnitude 5.2 star which is just visible to the naked eye under the very best of conditions. Bessel measured it distance as 11.4 light years.

Although 61 Cygni appears as a single star astronomers since 1830 has thought that it was a double star. Although there appeared to be confirmation of the double star status it was not until the 1930s that this was confirmed.







Monday, 23 November 2020

Astrognome 100 Great Stars No 80 Shaula

 

Shaula

Shaula or lambda Scorpii is the star that marks the sting of the scorpion. The name Shaula means the ‘Stinger’ With a magnitude of 1.6 Shaula is the second brightest star in the constellation of the Scorpion. Yet lambda is only the 11th letter of the Greek alphabet. This rather throws the system introduced in 1603 by Bayer on his Uranometria star atlas into some confusion. In theory the 24 brightest stars in a constellation should have a letter from the Greek alphabet allocated to it with alpha being the brightest followed by beta and ending in omega.



Shaula lies at a distance of around 570 light years. Like many stars it is not a single but a double and possibly a triple star system. Shaula is a B class giant star with a temperature of around 25,000 degrees much hotter than the Sun.

The companion star is believed to be a neutron star the result of a supernova explosion. What ever Shaula’s companion might be astronomers believe that at some point on the future lambda Scorpii will also become a supernova. That really will produce the sting of the tail of the scorpion.


Occultation of 73 Pisces from India with a Cooke

 

Occultation of 73 Pisces from India with a Cooke


The occultation of the star 73 Pisces by Jupiter was observed from Meean Meer, Lahore, India on December 23rd 1880 by H Collett using a 4.5 inch Cooke telescope with a power of 96.

At 01 hours, 52 minutes, 30seconds GMT the star was hanging on the limb of the planet and by 01 hour and 54 minutes it had entirely disappeared. The phenomenon strongly resembled the occultation of a satellite except the disappearance was more rapid. The planet and star appeared to cohere for about 1.5 minutes.

A sketch has been included.



No micrometer was used. The GMT of reappearance was 02 hour, 44 minutes when the star was again observed to hang onto the planet’s limb. The planet was well placed for observation being near the zenith.

Before and after the occultation Jupiter appeared as if with 5 moons, the star being almost indistinguishable from the satellites.

As the occultation could not be observed in Europe these few notes may prove to be of some interest.


The Astronomy Show

 

The Astronomy Show

Join me, Martin Lunn tonight and every Monday evening from 7.00 pm-9.00 pm on the Astronomy Show, I will take my weekly look at the night sky and look at all the latest news in astronomy. There will be the astronomical anniversaries this week plus the A-Z of Constellations and the Messier Marathon.



The Astronomy Show every Monday evening only on Drystone Radio 102 and 103.5 FM the show can be heard live on line at www.drystoneradio.com and the show can be heard later on the Drystone Radio Podcast.



Sunday, 22 November 2020

Astrognome 100 Great Stars No 79 Sirius

 

Sirius

As light from a star enters the Earth’s atmosphere the star is seen to twinkle but none like Sirius the brightest star in the sky. The light from Sirius often looks like the light of a rainbow. At magnitude 1.5 Sirius is not only the brightest star in the sky but it is also the brightest star in the constellation of Canis Major the Greater Dog. Sirius is often known as the ‘Dog Star’.



Sirius was very important in ancient Egypt because when it was seen for the first time before the Sun rises was the time that farmers had to put their seeds in the ground ready for the water from the river Nile which would shortly flood their fields. Leaving a cover of very fertile sediment to hopefully produce a good crop for the year. When Sirius was seen just before sunrise this is known as the Heliacal Rising.

The brightness of Sirius is part due to its closeness to us its a mere 8.6 light years away. Being a star with a spectral class of A0 its hotter than our Sun. It is also a binary star. The story behind the discovery of the companion star is fascinating in itself. In 1862 the American telescope maker Alvan Clark was testing a new telescope when he used Sirius to check how good the lens was and discovered Sirius B or as it is usually referred to as ‘The Pup’.



The pup is no ordinary star it was the first of the white dwarf stars to be discovered. Although much fainter than Sirius A the pup is much hotter and much older. It is the remains of a larger companion star. The star is formed of material that has been squashed together this material astronomers refer to as degenerate material, it is so heavy that a lump of white dwarf material the size of a snooker ball would weigh around 70 tons!! The Sun will one day become a white dwarf.


The 1866 Leonids seen from Liverpool

 

The 1866 Leonids as seen from Liverpool

The scientific section of the Liverpool and Historic Society held a meeting last evening (Thursday 15th November 1866) at the Free Library, William Brown-street.

Mr Wittingsall of Warrington presided.—Mr. Sansome opened a discussion on the meteoric showers on Wednesday morning. He said that he had been told by some men who were up all night that the finest display was at three o'clock the morning—much more numerous than in the early part of the night. He himself saw the meteors between one and half-past one, and there were three or four coming at time. He saw two fall apparently side by side, just like two streaks of fire. The larger ones were very brilliant. two appeared very much like large blue light falling, and threw a sort of halo round them. They left a streak of fire like a tail, and it was three or four seconds before it went out.



He saw some of the larger ones that certainly must have left a streak of fire of forty-five degrees. In a book treating of astronomy he found it mentioned that Boston in 1833, there was immerse shower if meteors. It was calculated that 39,000 stars fell each hour for seven hours, making a total of 273,000. It must, however, be recollected that that calculation was not made until the phenomenon was considerably on the decline. He had not seen any of the observations made during the present fall, but from what had learned from unscientific observers of what the fall was at about three o'clock in the morning, it must have been quite numerous it was at Boston in 1833. There was one thing to be said about this time, namely, that the sky was very much obscured with clouds for some considerable time, and it was only between those clouds that he had a view of the stars.

Mr J. Harding said he had stated in some of the papers that one or two of the meteors lasted for a minute.

Mr. Sansome said he did not think that could be; they died away in few seconds.

Mr. N. Waterhouse said he observed that in the eastern part of the sky the stars fell six at once, and the in the western sky three or four at once. They did not last more than three or four seconds each. He did not know whether they had any full or accurate idea of what the meteors were, but it struck him that they must merely of gaseous character. Some times there was a train, sometimes no train, and very often the head entirely disappeared whilst the train left in the sky. Sometimes the ball moved without any train, but there was a wriggling in the motion, and it was not always directly forward. He did not think they could lay claim they had seen as many as the Americans did in 1833.

Mr. Sansome said one theory was, that the meteors were planets moving very rapidly forward in opposite direction the earth, consequently they appeared to move much more rapidly than they actually did.

Mr. T. Gibson jun, said he observed the phenomena from 12 o'clock to 20 minutes to 1, and between 12 exactly and 29 minutes past counted in 100 in an arch of about one third the sky. He looked towards the east. The most he saw to fall at once were four—three very brilliant ones, and one without a tail. Some of them had a very wavy motion. Of the 100 which he counted, three were due north and south, the rest were nearly all east and west. Some them were exceedingly brilliant. One was so brilliant that in crossing the hall in the dark, after he had put out all the gasses, it quite lighted the hall, so that could see the whole of the stairs down below. He counted in the east about 280 hour, and in the west about 300.

Mr. Water house remarked that it looked like the bombardment of a town.

Mr. Sansome said that it appeared to him that they lost sight of the stars as soon as they came to certain height in the horizon—as soon as they came within the range of oar atmosphere. He thought our atmosphere was too dense to allow us to see them.

Mr. Waterhouse said they did not seem to be at great distance from the earth.

Mr. T. Gibson, jun., said they seemed to him to become luminous on reaching our atmosphere. They came within the region of air which illuminated them at once, and then they burned themselves out.

This closed the discussion

Saturday, 21 November 2020

Astrognome 100 Great Stars No 78 Sigma Octans

 

Sigma Octantis

Northerners seem almost vainly proud of their pole star, Polaris in Ursa Minor, as if nature put it there. Southerners they note have no pole star. They mumble grudging that, yes, there is one, though it is no more than the 5.5 magnitude star sigma Octants. Octans the Octant is one of the faint constellations that was added in the southern hemisphere 1750s by the French astronomer Nicolas Louis de Lacaille.



The brightest star in octants is Nu with a magnitude of 3.8, however sigma is the most important star in the constellation due to its location in the sky and since the 1700s sigma has been referred to as ‘Polaris Australis’

Sigma is an F0 class star with a surface temperature of 7,400 degrees making it hotter than our Sun which has a temperature of 5,800 degrees. Sigma lies at a distance of 280 light years. However astronomers in the southern hemisphere can take heart that due to the precession or wobbling of the Earth things are getting better with brighter stars marking the south pole until in the year 9100, the star delta Carina will be the South Pole star. At magnitude 2.0 delta is as bright as Polaris which marks the pole stars today for astronomers in the northern hemisphere.

Great Comet of 1882 seen from India with a Cooke

 

Great Comet of 1882 seen from India with a Cooke

The great comet of 1882 was first seen in September of that year and was observed and photographed by astronomers all around the world. This included from India.

On September 25th 1882 H Collett from Lahore, the Punjab, India observed the comet with a 4.5 inch Cooke telescope. At 04 hours and 50 minutes local time the comet was estimated to be about 14 degrees long and of unusual breadth. The borders of the tail appear much brighter that the central part.




Friday, 20 November 2020

Rev T E Espin, Liverpool Observatory and a Star Catalogue

 

Rev T E Espin, Liverpool Observatory and a Star Catalogue

In 1884 the Rev T E Espin published in the Transactions of the Liverpool Astronomical Society ‘ A Catalogue of the Magnitudes of 500 stars in Auriga, Gemini and Leo Minor’ which have been determined from photographs taken by means of the equatorial stellar camera at the society’s observatory.



The apparatus was placed at the disposal of the society by the telescope maker Mr Howard Grubb. The magnitudes determined from the photographs are entirely based on those of Argelander. It is stated that the deduced magnitudes of 341 stars out of 500 agree within 0.4 magnitude with those of Argelander. There were however 25 cases when the difference was a whole magnitude.

Mr Espin commented that near the minimum visibility the bluer stars alone are photographed, the yellowish ones disappearing.



Astrognome 100 Great Stars No 77 RS Ophuichus

 

RS Ophuichus

RS Ophiuchus is a star to watch, it is another of the recurrent novae that are known to astronomers. It is only in the last 25 years or so that astronomers have realised that all novae are actually recurrent, they all become nova over a period of time measured in either decades or maybe centuries.



Usually nova were called by the year they were observed, so Nova Hercules 1934 or Nova Cygnus 1975. On this basis RS Ophichus becomes Nova Ophiuchi 1898, 1933, 1958, 1967, 1985 and 2006. RS lies at a distance of around 5,000 light years.



RS so far has never become bright enough to be seen with the naked eye, it’s normally at magnitude 15 and has brightened to around magnitude 9.0. There are 2 stars in the RS system one a red giant, the other a white dwarf. There question today is when will RS Ophiuchus go nova again, it could even be tonight.





Thursday, 19 November 2020

Comet Pigott 1783

 

Comet Pigott 1783

Edward Pigott one of the ‘Fathers of Variable Star Astronomy’ also discovered a comet. On November 19th 1783 he noticed a small nebulous patch in the constellation of Cetus. He discovered the comet using a 2.5 feet long telescope made by Dolland. The comet was below naked eye visibility when discovered. Pigott last saw the comet on December 3rd 1783. Pigott was the first Englishman to discover a comet and have it named after him.

The comet was then lost to astronomers, this was because there were so few observations of the comet that it was not possible to work out the comet’s orbit. It was assumed to be a lost comet.

Then in January of 2003 the LINEAR survey found a “new” comet with their telescopes outside of Socorro, New Mexico. The comet was designated Comet C/2003 A1 (LINEAR), a suggestion was made that it might be a return of long-lost Comet Pigott. Unfortunately, it was not possible to make a definite link between the 2003 LINEAR comet and Piggot’s 1783 find.

On the night of September 10th 2009, Rich Kowalski of the Catalina Sky Survey was surveying the sky for unknown comet and asteroids when he came across a possible new comet. It was none other than Comet Pigott. When discovered in 1783 the comet was bright enough to be seen in a small telescope, today a powerful telescope is needed as the comet is around magnitude 17. Today we know that the comet has an orbital period of around 6 years.



In a 237 year period the comet has changed its name three times from comet Pigott, to comet Pigott-LINEAR, to comet Pigott-LINEAR-Kowalski!!!!!

Astrognome 100 Great Stars No 76 RR Lyrae

 

RR Lyrae

Many people know of the Cepheid variable stars which are used to work out the distance to clusters and galaxies. The prototype delta Cepheus was discovered by the death astronomer John Goodricke in York in 1784. These cepheids have periods of between a few days up to 50 days. The classical cepheids are normally found along the galactic plane. At the lower end of the scale of these pulsating variables with periods of less than a day astronomers find the RR Lyrae stars.

RR Lyrae was discovered in 1899 Williamina Fleming one of the women computers working at Harvard. RR Lyrae stars are fainter than the classical cepheids having magnitudes between 7.0 and 8.0 below naked eye visibility and are typically found in globular clusters.



Globular clusters are older than open clusters. Originally referred to as cluster variables RRLyrae stars can be found throughout the Milky Way although around 80% will be found in the globular clusters. The RR Lyrae stars are an additional aid to help astronomers work out distances within out galaxy.

RR Lyrae stars are not only known of in our galaxy but recently using the Hubble Space Telescope astronomers have discovered RR Lyrae stars in globular clusters in the Andromeda Galaxy.

Wednesday, 18 November 2020

Astrognome 100 Great Stars No 75 Rigel

 

Rigel

A well known star, Rigel is part of the constellation of Orion which is marked by 4 stars that form a very prominent rectangle during the winter nights. Rigel is a blue supergiant star lying at a distance of 860 light years and shinning with a magnitude of 0.1. When people are trying to show the colour differences in stars they often use Rigel as a blue star in comparison with Betelgeux the top left hand star in the rectangle that forms Orion as a red star.



Rigel marks the bottom right hand point of this rectangle. Its name comes from the Arabic ‘The left leg of the Giant’. Although listed as beta it is in fact the brightest star in Orion. There are at least 4 stars in the Rigel system.

Rigel is estimated to be about 8 million years old. It has a surface temperature of 12,000 degrees however earlier in it’s evolution it would have been a massive 30,000 degrees. It is loosing mass at an incredible rate and like all giant blue stars it will like many of the stars that are in Orion end its life as a supernova.




Andromedid Meteor Shower seen over Birkenhead

 

Andromedid Meteor Shower seen from Birkenhead

On Wednesday November 27th November 1872 a large meteor shower was seen over the UK including a report from Birkenhead. Here is a report from G. H. H. of Birkenhead, I have no other details as to the identity of the observer.

Starting at 5.25 pm I saw the first meteor. Between 5.35pm and 5.50 pm 150 were counted by one observer in the sky towards the North East. At 6.26 pm in 4 minutes, 5 observers counted 310. At 6.40 pm in 2 minutes, 5 observers counted 316. At 8.37pm with a hazy cloud to the North 6 observers in 5 minutes counted 528 while facing South east.



A very few among so many left visible streaks of light after the meteor itself had disappeared with 15 seconds being the longest time any of them remained visible.

They appeared to radiate from a point a little to the south of mu Cassiopeia, many in the vicinity of that star having courses of less than one degree in angular measurement.

Towards 10 pm clouds covered the greater part of the sky, so that only unusually brilliant meteors could be seen; They were however, again visible but in decreased numbers at 11.30 pm.


This meteor shower was the Andromedid meteor shower and was the remains of comet Biela that was observed to break up.

Tuesday, 17 November 2020

Astrognome 100 Great Stars No 74 Rho Ophiuchus

 

Rho Ophiuchus

If you don’t live in the southern hemisphere and cannot see Acrux in the constellation of Crux the Southern Cross then take a look at Rho Ophiuchus it’s more northerly clone. Rho at magnitude 4.6 is not as bright as Acrux at magnitude 0.8. the rho Ophiuchus system is made up of two blue stars which take around 2,000 years to orbit each other.



Rho lies at a distance of 380 light years and lies within a complex of bright and dark nebulae. The Rho Ophiuchus dark cloud is located just north of Antares in Scorpius. Rho is surrounded by IC 4604 a reflection nebula similar to that which surrounds Merope in the Pleiades. The letter IC stand for the Index Catalogue of clusters and galaxies that was stared in 1895.



IC 4604 is around 10 light years across and is the illuminated part of a nest of thick dark, dusty clouds. The dust blocks a large amount of light from rho reaching us and if not for the dust rho would be seen as a star of magnitude 2.0. Inside these clouds of gas are many proto stars that are in the process of forming into proper stars. Although with our eyes we can only seen rho we do know what is going on in the clouds around this star.

Astronomical Lectures from Eccles

 

Astronomical Lectures from Eccles


The committee of the New Jerusalem Church Day and Sunday Schools, Ramsbottom have engaged T Mackereth Esq FRAS of the observatory, Eccles near Manchester to give two lectures at the Co - Operative Hall, Bolton Street, Ramsbottom on Friday November 17th and Friday November 24th 1865. 

The lectures will be illustrated by diagrams and apparatus.

Admission reserved seats 6d back seats 2d

Monday, 16 November 2020

Astrognome 100 Great Stars No 73 Rho Cassiopeia

 

Rho Cassiopeia

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?



Rho is estimated to be around 8,000 light years away, stars are classed as either dwarfs or giants or even supergiants but rho is one the incredibly massive stars classed as a hyper giant. There may only be about a dozen known which include eta Carina and P Cygni. Even among hyper giants rho is rare as most are either red (cool) of blue (hot) but rho is in between it is a yellow hyper giant.

Rho has been classified as a massive luminous unstable star which is pulsating which is why we see the magnitude change and its loosing mass. In 2013 a shell of gas caused rho to fade in brightness by around half a magnitude. Then in 2017 rho brightened to magnitude 4.3 the it brightened again in 2018 this time to magnitude 4.2.

Rho is one of the most luminous yellow stars known, it is very close to what is known as the ‘Eddington Luminosity Limit’ . This is the maximum luminosity that a star can achieve where there is a balance between the force of radiation acting outwards and the gravitational force acting inwards. Rho does not have much time left before it becomes a stunning supernova.



Nova Aquila 1918 and Manchester

 

Mr Butterworth of Manchester and Nova Aquila 1918


In the Journal of the Manchester Astronomical Society for the session 1917-1920 a series of photographs showing the spectra of Nova Aquila 1918 taken by Mr C F Butterworth using a 6.3 inch prismatic reflector were published. The period covered was from June 10th to November 14th 1918. A series of 36 photographs were taken on 22 different nights.


The general sequence of changes in the spectrum is well shown, and many of the smaller details- such as the complex structure of the hydrogen bands may also be detected. The series as a whole forms a useful addition to the observations already published concerning this important nova.


In addition Mr Butterworth gives a table of measures of the breadths of the more important bright bands at four different stages of the star’s career.

The Astronomy Show

 

The Astronomy Show


Join me, Martin Lunn tonight and every Monday evening from 7.00 pm-9.00 pm on the Astronomy Show, I will take my weekly look at the night sky and look at all the latest news in astronomy. There will be the astronomical anniversaries this week plus the A-Z of Constellations and the Messier Marathon.



The Astronomy Show every Monday evening only on Drystone Radio 102 and 103.5 FM the show can be heard live on line at www.drystoneradio.com and the show can be heard later on the Drystone Radio Podcast.




Sunday, 15 November 2020

Edmund Salter in Manchester and Jupiter

 

Mr Edmund Salter in Manchester and Jupiter

On November 15th 1870 Mr Edmund Saletr of Manchester at 10 hours and 16 minutes using his 12 inch silvered glass reflector observed the transit of Jupiter’s third satellite.

The weather was fine throughout so that the satellite remained conspicuously visible during its entire passage across what may be called the Antarctic circle of its primary.

The shadow was densely black and larger than the satellite.

Astrognome 100 Great Stars No 72 Regulus

 

Regulus

Regulus is the brightest star in the constellation of Leo the Lion a ferocious beast that was killed by Hercules as one of his twelve labours. In the sky however it must be said that Hercules is much less imposing than Leo. In spring Leo is easily seen in the sky and Regulus is located at the bottom of a backwards looking question mark of stars in the sky.



Regulus is the faintest of the first magnitude stars with a magnitude of 1.4. First magnitude stars are classified as stars brighter than magnitude 1.5. Regulus is a B class star hotter than our Sun and lies at a distance of 79 light years. It was always considered by the Persians with Aldebaran, Antares and Fomalhaut as a royal star.

Regulus although appearing as a single star is in fact a quadruple system. It is one of the few bright stars in the zodiac that can be occulted by a planet. The last time this happened was in 1959 when the planet Venus passed in front of Regulus the next time Venus passes in front of Regulus will be in 2044.


Saturday, 14 November 2020

Joseph Gledhill, Jupiter and a Cooke

 

Joseph Gledhill, Jupiter and a Cooke

Joseph Gledhill astronomy assistant to Edward Crossley at the Park Road Observatory in Halifax and using the 9.3 inch Cooke telescope observed Jupiter from November 4th 1869 until December 31st 1869. He observed the Great Southern Ellipse which was easily visible on November 11th 1869.



It lay between bands 5 and 6 touching 6 but not quite in contact with 5. Its length was about one third that of the band 6. Its east end was the darkest part of it and also the broadest. In other parts it was a fine narrow sharp dark line. The space within it was bright but not brighter than that of the zone in which it lay. No spots or marks could ever be detected within it, nor could any change in size be discovered.


The 9.3 inch Cooke is still in use today at the Carter Observatory in New Zealand.

Astrognome 100 Great Stars No 71 Rasalgethi

 

Rasalgethi

Among the oldest celestial figures known, Hercules was handed down to us by the ancient Greeks though not he brightest star in Hercules Rasalgethi marks the head of Hercules and is therefore allocated the Greek letter alpha. In addition it must have been at its very brightest when Bayer allocated it the letter alpha. Its a red giant star variable star varying between magnitude 2.7 to 4.0 and lying at a distance of around 360 light years.


Astronomers have discovered that Rasalgethi is actually a triple star system with a companion yellow giant star with a magnitude of 5.4 and a fainter F dwarf star. Some astronomers describe the brightest stars as a remarkably lovely pair with colours of orange and emerald. The pair take around 3,500 years to orbit each other.

The two larger stars are dying Rasalgethi will loose all of its gas first and end up as a white dwarf with its yellow giant companion star taking the same path in the future ending up as a white dwarf leaving the F class dwarf star as king of the system until it finally reaches the white dwarf stage. The Rasalgethi system will then end up as a triple white dwarf system.





Friday, 13 November 2020

Franklin Adams Charts and a 10 inch Cooke

 

Franklin Adams Charts and a 10 inch Cooke

John Franklin Adams photographed the entire night sky between 1904 and 1909 from Godalming in Surrey from the northern hemisphere and the southern hemisphere South Africa using a 10 inch Cooke camera and two 6 inch Cooke cameras.



In 1913 the Royal Astronomical Society undertook to publish a small number of the Franklin Adams Charts. The 206 photographic plates covered the entire sky. Each plate covered an area 15 degrees by 15 degrees.



The reproductions were on bromide paper 15 inches by 12 inches with the plate area being 11inches by 11 inches. The cost of each set will be 10 guineas in 2020 this would be over £1,150!!

It is hoped that a sufficient number of subscribers will be enlisted to help to defray the cost of such an expensive undertaking. It is hoped that they will be ready in 1914.

Today the Franklin Adams Charts are still used by astronomers due to their quality and their historical reference to the night sky of over 100 years ago.


Astrognome 100 Great Stars No 70 R Monocerotis

 

R Monocerotis

The constellation of Monoceros the Unicorn occupies the area between Orion, Canis Major and Canis Minor in the winter skies, there are very few bright stars in the constellation. It is a ‘modern’ constellation added to the sky in the 17th century.


When the great 200 inch Hale telescope became operational in 1947 one of the first photographs taken was of NGC 2261, Hubble’s Variable Nebula in the constellation of Monoceros. In 1916 Edwin Hubble after who the Hubble Space Telescope is named discovered that this fan shaped nebula was uniquely variable. There were large changes in brightness up to 4 magnitudes. In the apex of the nebula was a star R Monocertis which had been observed since 1861.



R Mon is surrounded by gas, its magnitude is listed at 11.8 but the gas is so deep that is obscures light from the star by around 15 magnitudes! It is believed that R Mon is a T Tauri type star a star that is in the process of becoming a proper star. It is believed that the disc of gas that surrounds the star is about the same size as our solar system.

R Mon lies at a distance of around 2,600 light years. Astronomers know of many stars that have planets orbiting them, One question that astronomers pose is could there be planets forming here?


Thursday, 12 November 2020

Astrognome 100 Great Stars No 69 R Leporis

R Leporis

Some ancient constellations are less well known than others. Lepus the Hare is one of those constellations. It can be found at the feet of Orion the Hunter, low in the sky in the south during winter evenings. Sometimes these quite often overlooked constellations have very interesting stars and this is the case in Lepus. Here we have the variable star R Leporis ‘The Crimson Star’



R Leporis was discovered by the English astronomer J R Hind in 1845 it is a Mira type red giant variable star. It varies between magnitude 5.8 to 11.7 in a period of between 418 to 441 days. R Leporis is called the crimson star because of its extraordinary colour. It has been likened to a glowing coal in a black sky. Hind’s crimson star makes William Herschel’s Garnet Star (Mu Cepheus) seem to pale by contrast.

So what contributes to the colour of the Crimson Star, first its temperature it is a very cool 2,100 degrees making it one of the coolest red giant stars known. However more importantly is the carbon which astronomers have discovered it the outer parts of the star’s atmosphere which then blocks out any blue parts of the visible spectrum we see coming from R Leporis.



In mythology every winter evening Orion chases the Hare across the sky and every night the hare escapes ready for the chase to begin on the following winter’s night.



Cooke Instruments were of the highest quality, But..........

 

Cooke Instruments were of the highest quality, But…….

Cooke Instruments were of the highest quality but by the 1920s with a slump in trade around the world for optical instruments Cooke’s were now discovering the penalty of making instruments too well, they did not need repairing!!

With this in mind in the late 1920s Cookes which by his time was trading as Cooke, Troughton and Simms undertook a major advertising campaign encouraging people who had brought equipment in the 19th and early 20th centuries to bring them back and have them repaired. This particular advertisement was from 1927.



The campaign was not just in the UK it was also global, and senior salesmen were sent to the various Cooke offices around the world to try to drum up extra business. It worked briefly but sadly for Cookes and other major industries around the world the Great Wall Street Crash in 1929 signalled the beginning of the Great Depression in the 1930s and the demand for optical instruments ceased almost overnight..



Wednesday, 11 November 2020

Astrognome 100 Great Stars No 68 R Corona Borealis

R Corona Borealis

A pretty semi circle of stars Corona Borealis the Northern Crown graces the northern spring and early summer skies. Within it lies one of the rarest and oldest stars that can be seen with the naked eye. This is R Corona Borealis a variable star that was discovered by Edward Pigott in 1795. Pigot worked with the deaf astronomer John Goodricke in York between 1781 and 1786 and is one of the ‘Fathers of Variable Star Astronomy’



When at its brightest R CrB is about magnitude 6 which means that if you have a clear dark sky you can just about see it, when it fades down to as faint as magnitude 15 a large telescope is needed to find the star. It does this at irregular intervals sometimes separated by months or even years. It can sometimes fall in brightness slowly or very quickly and the rise back to maximum brightness almost as soon as minimum is reached. So what is going on?

R CrB is the prototype star for this small group of stars that have a cloud of soot form around then from the condensation of carbon rich dust. As the dust cloud forms the star is masked by this cloud of dust, the brightness of the star is affected and we see the star fade in brightness. Then when the cloud of soot clears R CrB returns to normal brightness.

R CrB is an old star and is only one of two stars in this class that can be seen with the naked eye the other is RY Sagittarius and is sometimes referred to as a reverse nova. The star will continues its long slide into white dwarf hood in the future.


Transit of Mercury seen from Australia with a Cooke

 

Transit of Mercury seen from Australia with a Cooke

On November 11th 1940 a transit of Mercury was visible for Britain that same transit was also visible from Australia on November 12th due to the different time zones.

A transit of Mercury occurs when the planet passes if front of the Sun as seen from Earth. Mercury can then be seen as a dark spot slowly moving across the Sun. Although not as scientifically important as transits of Venus, transits of Mercury still attract a lot of attention. The most recent was in 2019 the next will be in 2032.



The Transit of November 12th 1940 was seen by Mark Howarth at the Grange Mount Observatory, Newcastle New South Wales, Australia. A Cooke 4.5 inch telescope was used with a solar diagonal of power x 80. Weather conditions were good, especially at times of the beginning and ending of the transit.

A slight haze made it impossible to obtain satisfactory photographs. The temperature at the time of the transit was 92 degrees F. or if you prefer 33 degrees C.