MEETINGS

 

 

COMMITTEE MEETING

 

        Members of the Committee are respectfully reminded that there is a meeting of the Committee on Tuesday 10th April 2012 starting at 1930 at Phil Berry’s house.

        As always, any member of the Society is welcome to join them but please let Phil know before hand.

 

 

MARCH  MEETING

 

        Phil Berry opened the meeting by welcoming back John Wayte after a successful heart operation.  Also we were glad to see Mike Wyles back after chipping a bone in his shoulder after a fall in his garden.

        He then introduced tonight’s speaker, Dr. Ben Richie.  Phil said Ben had achieved his PhD, studying Theoretical Astro Physics although he is now into research in Observational Astronomy where almost all of his research is done on the European Southern Observatory’s VLT in Chile.  His particular interest is in massive stars in our own and nearby galaxies.

 

 

In Search of the Most Massive Stars

Dr Ben Richie

 

        Ben began by taking us through how the earliest stars formed and said that they are now so far away from us and the expansion of the Universe has moved their light into the infra-red so now we are really waiting for the next generation of telescopes to come along to be able to detect them.  In the meantime astronomers are working with theoretical models.

        The models suggest that the earliest stars would have been as big as 1,000 solar masses, developed very quickly and lasted only a short time.  The model also shows that today stars could probably be created up to about 500 solar masses and might just remain stable.

        Most of our knowledge now comes from observing binary stars.  By using Kepler’s laws it is possible to work out the masses of two orbiting stars to quite a high degree of accuracy, although single stars are more difficult to ‘weigh’ where light coming from the star is broken down into its spectra and used in the theoretical model to achieve an estimate.

        Ben told us that the most massive star known to date in our own area of galaxies is R136a1 which is about 255 times the mass of our Sun but when originally created was probably 350 times, then shed much of its outer material over its life time.

        Research into these massive stars is important because it helps to determine how galaxies form.

        What happens towards the end of the life of these massive stars helps researchers to understand how they work and also help check the accuracy of the models.

        At the end of the life of a star similar to the mass of the Sun helium starts fusing into carbon but then stops.  In more massive stars, to say about 10 solar masses, carbon can burn to oxygen and neon.  Then the star becomes a white dwarf.

        Even more massive stars start forming iron but when the core gets too large it collapses down to a neutron star, and then the star becomes a super-nova.

        Ben briefly talked about the structure of a red-supergiant where hydrogen burns to helium, helium burns to carbon, carbon to oxygen and so on to iron in the centre which grows to where it can no longer support itself and it becomes a type 2 supernova.   He said the only difference between a type 1 and type 2 supernovae is that there is no hydrogen in a type 1.

        Because photographs of nearby galaxies have been recorded now for over a century, it is possible to identify which star it was that has become a supernova, and we were told about a blue star that exploded and was seen in 1987 in the Magellanic Cloud and another more recently in M51, this time a yellow star similar to our own Sun but extremely large.

        Much closer to home is the constellation of Orion and Ben talked about the star creation taking place in Orion’s belt, where many of the blue supergiant stars formed 3 to 5 million years ago.  Betelgeuse, the red supergiant top left of the constellation is 1,200 times the radius of the Sun.  We next looked at Rigel at the bottom right of Orion and is a blue supergiant about 75 times the size of the Sun.

        Then Ben posed the question what would Orion look like in say 20,000 years’ time.  The most likely answer would be that Betelgeuse would not be there and Rigel would probably have become a red supergiant.

        Although Ben said there was also an alternative possibility.  Betelgeuse could have become a hot blue star but fainter and Rigel may have exploded first.  This transition would occur as a result of shedding the star’s outer hydrogen-rich layers due to very high velocity stellar wind.  This type of star is called Wolf-Rayet and only the core remains.  When this type of star collapses as a super-nova, since there is virtually no hydrogen or helium left it forms a type 1 super-nova.

 

      

 

        A Wolf-Rayet star taken by NASA’s Hubble Space Telescope
.  The star is in the centre of this nebula called M1-67

 

        Not a great deal is known about Wolf-Rayet stars although there is a star that is going through this transition stage now in Eta Carinae.  About two hundred years ago this star was the second brightest star in the night sky but now it is obscured optically by a thick cloud of dust although this is thought to be clearing and we are just beginning to see it brighten again.

        Star clusters are useful in that they are all formed about the same time and so have the same age.  Ben said one such cluster called Westerlund 1 with a high number of massive stars had been found in our galaxy and this is where much of his research is concentrated, although as he said it is difficult to observe because of thick dust and most of the work has to be done in the far infra-red.

        Westerlund 1 contains 4 red super giants and 24 Wolf-Rayet stars with hundreds of blue super giants.  Many of the objects have already reached the end of their lives so this makes the cluster very useful for research.

        At the centre of our galaxy and surrounding a black hole are clusters of massive stars known as the Quintuplet Clusters, but because of dust, there are 12 ‘magnitudes of extinction’, so nothing can be seen in normal light and only just discernible in infra-red.  But they are changing very rapidly indeed and many of them will already have reached the end of their lives.

        One of these stars is one of the most luminous stars in the galaxy and known as the Pistol Star.  It is a blue variable and is probably about 2 to 4 million times the luminosity of our Sun and about 80 to 150 times its mass.

        Very close to the Quintuplet cluster is the Arches cluster and the massive stars hear are much younger and this is proving to be also very useful for research into the most massive stars, but as Ben says, watch this space!

 

 

John Wayte’s scientific snippets

 

        It was good to see John back and again he produced more snippets from the world of science.

        Recently the OPERA (Oscillation Project with Emulsion Racking Apparatus) experiment at CERN claimed that some neutrinos arrived faster than the speed of light, but that may prove to be false.

        Following extensive re-testing it was found that there may have been a leak in the fibre optic cable from the GPS receiver at ground level to the OPERA master clock below.

        Also the clock was checked against an even more accurate atomic clock and it ticked of the milliseconds ever so slightly faster that it should.

        Einstein may have been proved right!

        John was rather put on the spot now because his second note was on the largest known star, following on from Ben Richie’s excellent talk.

        John had read that the largest known star is VY Canis Majoris, 1,800 to 2,100 solar radii; 1.9 billion miles in diameter and if in the Sun’s place would reach out to beyond Jupiter!  

   

        It is very unstable and could explode as a hypernova in the next 100,000 years.  This would result in a large black hole.  Although as John said with relief; it is 4,900 light years from us.

        Ben confirmed this with a professional astronomer’s reserve…

  Comparison of VY Canis Majoris with our Sun

 

Street Lighting Update

Phil Berry

 

        Further to Phil’s concerns with street lighting around Wadhurst, he gave a progress report and said he had been in touch with “Campaign for Dark Skies” and they had sent him a number of useful links.

        He had also heard from the Parish Council with particular regard to the type of bulbs being used as old ones failed. He is now doing further night sky measurements in the early hours.

         Phil said how surprised he was to see so many “Security Lights” on and felt this helped rather than hindered criminals.

 

 

Sky Notes

Brian Mills

 

        This month, Brian continued his theme of constellation recognition.

        By using the two stars, at the rear of the Plough, Merak and Dubhe and continuing up, it leads to Polaris, the North Star.  Continuing on, we come to Ursa Minor, made up of much fainter stars.

        From Mizar, the double star in the handle of the Plough and drawing a line through Polaris, it brings us to the “W” of Cassiopeia. Then using the right-hand two stars of the “W”, a line upwards brings us to Cepheus.

        Again from the Plough and drawing a line continuing along the handle leads to a bright star, Arcturus, the brightest star in the constellation of Boötes.

        At the moment, between Boötes and the horizon is the constellation of Corona Borealis.

        From the rear two stars of the Plough again, but drawing an imaginary line away from Polaris we come to the sickle of Leo where the brightest star at the bottom of the sickle is Regulus.

        From the belt of Orion and drawing a line left brings us to the brightest star in the night sky, Sirius in Canis Major.

Drawing a line from Orion’s belt in the other direction points almost to the bright star, Aldebaran and then beyond that we come to the open cluster of the Pleiades.

        Brian then turned to the sky notes which follow later in this Newsletter.

 

APRIL MEETING

 

        Wednesday 18th April 2012 – Steve Richards talks about “Making Every Photon Count”.  He has written a book of the same name and it is a beginner’s guide to Deep Space Astro –photography and will have copies available with him at £19.95 a copy.

        Meetings begin at 1930 although members are invited to arrive anytime after 1900 as this is a good time to exchange ideas and discuss problems and also relax before the meeting.

        The venue as always is held in the Upper Room of the Methodist Church at the east end of Wadhurst Lower High Street, opposite the entrance to Uplands College.  (For those with SatNav – the post code is TN5  6AT)

        Anyone is welcome but non-members are asked if they wouldn’t mind contributing £2 towards costs.

 

 

FUTURE  MEETINGS

       

 

        Wednesday 16th May 2012 – Our Director of Observations, Brian Mills will be giving a talk entitled “Astronomy – Its Relevance and its Women”.

 

        Wednesday 20th June 2012 – The Society’s Telescope Evening.

 

        Wednesday 18th July 2012 – Details to follow.

 

 

 

OTHER NOTES AND INFORMATION

 

KEELE OBSERVATORY’S 50TH BIRTHDAY

KEELE UNIVERSITY SATURDAY 19TH MAY 2012

 

        All are welcome – free entry but by ticket only.

        Keel Observatory was founded in 1962 by Dr. Ron Maddison.  It is home to a 31 cm Grubb refractor built in 1874 for Oxford Observatory, and various other historical and (more) modern telescopes including a solar H-alpha telescope and a 61 cm reflector.

        Speakers include: Prof. Allan Chapman, Dr, Ron Maddison, William Leatherbarrow, and a representative from the Euriopean Southern Observatory.

        For more details see:

http://www.astro.keele.ac.uk/Observatory

 

 

 

SUBSCRIPTIONS FOR 2012

 

        We have now entered the Society’s new session, and again, the subscriptions remain the same as in recent years.  Membership for the year is still £15.00 and £20 for two members within the same family at the same address.  Children and students are free and always welcome.

        Subscriptions can be made at the meetings, preferably by cheque payable to “Wadhurst Astronomical Society” or can be posted to our Treasurer, Michael Wyles at:

31 Rowan Tree Road

Tunbridge Wells

Kent

TN2  5PZ

 

        Visitors to meetings are asked if they wouldn’t mind contributing £2 towards costs.

 

 

SKY NOTES FOR APRIL

 

Planets

 

Mercury is a morning object, after passing through inferior conjunction on March 21st, and reaches greatest western elongation on the April 18th. However, due to the angle that the ecliptic makes at this time of year, the planet is only around 4° high at sunrise and therefore unobservable.

        Had this coming apparition occurred in October, then you can see from the diagrams that the angle the ecliptic makes with the horizon would have meant it was higher in the sky and therefore more easily observable.

 

 

 

Venus is still a brilliant evening object at magnitude -4.5. It spends the whole of this month in Taurus, setting some four hours after the Sun. The apparent size of the planet continues to increase whilst the percentage of the illuminated hemisphere turned towards us decreases from 48% down to 27%. On the 2nd, 3rd and 4th it is very close to the Pleiades cluster (as shown in the diagram) offering a possible photographic opportunity. On those dates Venus can be found almost exactly due west and 25° high at 2100 BST. You will have no trouble locating it as it is the brightest thing in the sky at that time (apart from the Moon which is in the south south east).

 

 

 

 

Mars reached opposition on March 3rd and is now fading. It is moving retrograde in Leo for the first part of the month until it reaches its second stationary point on the 14th after which it continues with direct movement (east to west) once more. (See the “Saturn” map for position).

 

Jupiter is in Aries at magnitude -2.0 but will soon be lost in the glare of twilight as the planet heads towards a solar conjunction on May 13th.  It can next be seen when it becomes visible as a morning object in the latter part of June.

 

Saturn at magnitude +0.3 lies in the constellation of Virgo, close to the bright star Spica and reaches opposition on the 15th of the month. At the beginning of April it rises at 2045 BST, but by the end it rises in daylight at 1845 and culminates at midnight. The north pole is currently tilted towards us at an angle of almost 14° giving excellent views of the ring system. This angle increases through the year until in December it has reached almost 19°. The map below gives its location (and that of Mars) mid-month although these positions will change little over the course of April.

 

 

 

Lunar Occultations

        In the table below I’ve listed events for stars down to magnitude 7.0 that occur before midnight although there are many others that are either of fainter stars or occur at more unsociable hours.  DD = disappearance at the dark limb and RB = reappearance at the bright limb.  Times are in BST.

 

Apr.

Time

Star

Mag

Ph

Alt °

%

illu

1st

2330

SAO 97913

6.3

DD

40

71

25th

2130

zeta Tauri

2.9

DD

24

17

25th

2152

zeta Tauri

2.9

RB

21

17

28th

2058

SAO 97628

6.2

DD

44

44

29th

2351

kappa Cancri

5.2

DD

24

55

 

        On the evening of April 25th zeta Tauri disappears behind the dark limb of the Moon, reappearing some 22 minutes later at the bright limb. Observers in northern England and southern Scotland will be treated to a graze occultation when the star will pass so close to the Moon that it can be seen appearing and disappearing between the lunar mountains and valleys. Timings of these events are used for many purposes, one being (perhaps surprisingly) the calculation of the solar diameter. This will be the brightest star this year to suffer a lunar occultation and as it occurs in the evening at a reasonable time we intend to organise a Society event to observe it. Observing and timing “total” occultations is an excellent way to practice for graze events. Last year observers from WAS carried out a successful graze observation and sent data to IOTA (The International Occultation Timing Association) to  assist in calibrating the lunar limb at the point that the event occurred.

        If you would like information about this occultation or would like to join us, then please contact me at the address/telephone number at the end of this newsletter. As the star is so bright, a telescope of 40 mm diameter is all that’s required, and possibly even binoculars will suffice. The Society has some telescopes and timing equipment that anyone interested can use.

        The diagram below shows the position of the star relative to the dark portion of the Moon which will be lit by Earthshine at the time of the occultation. This will make the observation easier as you can see the star approaching the dark limb and need only to concentrate when the event is imminent.

 

 

 

 

 

Phases of the Moon for April

 

Full

Last ¼

New

First ¼

6th

13th

21st

29th

 

 

ISS

        Below are details of passes of the International Space Station (ISS) that occur before midnight and are brighter than magnitude -2.0. The details of all passes including those visible from other areas can be found at:

www.heavens-above.com

        Please remember that the times and directions shown below are for when the ISS is at it’s maximum elevation, so you should go out and look a few minutes beforehand . Times are in BST.

 

Apr.

Mag

Time

Alt°

Az.

12th

-2.8

21.15

38

SSE

13th

-3.5

21.53

79

SSE

14th

-3.0

20.55

51

S

14th

-2.8

22.30

56

WNW

15th

-3.4

21.33

86

N

16th

-3.0

20.35

61

SW

16th

-3.4

22.11

79

N

17th

-3.3

21.13

79

N

17th

-2.1

22.48

37

W

18th

-3.4

21.51

87

N

19th

-3.3

20.53

78

N

19th

-2.9

22.29

49

SW

20th

-3.4

21.31

78

SSW

21st

-2.7

22.09

38

SSW

22nd

-3.2

21.10

59

SSW

24th

-2.2

20.50

39

SW

 

 

Iridium Flares

        The flares that I’ve listed are magnitude -4 or brighter although there are a lot more that are fainter, occur after midnight or at a lower altitude. If you wish to see a complete list, or obtain timings for somewhere other than Wadhurst, go to:

www.heavens-above.com

        Remember that when one of these events is due it is sometimes possible to see the satellite in advance of the “flare”, although of course it will be much fainter at that time. Times are in BST.

 

Apr.

Time

Mag

Alt°

Az.

1st

1949

-6

69

SSE

4th

2209

-7

38

ENE

4th

2232

-4

21

NE

8th

2227

-5

29

NE

10th

2227

-4

32

ENE

11th

2218

-7

33

NE

14th

2034

-7

68

ESE

15th

2028

-6

69

ESE

18th

2154

-7

45

ENE

22nd

2139

-4

52

ENE

22nd

2255

-6

15

NNE

26th

2249

-6

23

NE

27th

2118

-5

59

ENE

28th

2117

-4

61

ENE

29th

2241

-6

28

NE

 

The Night Sky in April (Written for 2200 BST mid month)

In the east Bootes, Corona Borealis and Hercules are fully risen. The constellation of Virgo is now well placed meaning that Saturn, close to Spica, is around 20° above the south eastern horizon.

Looking south both Hydra and Leo are straddling the meridian. The head of Hydra is easy to identify by using the “Twins”, Castor and Pollux, and drawing an imaginary line through them and continuing it in the direction of the horizon as shown by the dotted line in the diagram.

 

 

 

 

        In the west the bright winter constellations are beginning to set. Orion and Canis Major are on the horizon although Procyon in Canis Minor and Capella in Auriga are still both at respectable altitudes.

        To the north the Plough is almost directly overhead, meaning Cepheus, opposite the pole from it, is a little above the horizon. To the east of the meridian lie Draco and Ursa Minor whilst to the west we find the “W” of Cassiopeia. Deneb in Cygnus and Vega in Lyra can both be seen above the north eastern horizon.

 

Advanced Warning for May

26th - The Moon passes in front of the open cluster M67.

 

Brian Mills

 

 

NASA’S SPACE PLACE

 

The Planet in the Machine

By Diane K. Fisher and Tony Phillips

 

        The story goes that a butterfly flapping its wings in Brazil can, over time, cause a tornado in Kansas. The “butterfly effect” is a common term to evoke the complexity of interdependent variables affecting weather around the globe.  It alludes to the notion that small changes in initial conditions can cause wildly varying outcomes. 

        Now imagine millions of butterflies flapping their wings.  And flies and crickets and birds.  Now you understand why weather is so complex.

        All kidding aside, insects are not in control.  The real “butterfly effect” is driven by, for example, global winds and ocean currents, polar ice (melting and freezing), clouds and rain, and blowing desert dust.  All these things interact with one another in bewilderingly complicated ways.

        And then there’s the human race. If a butterfly can cause a tornado, what can humans cause with their boundlessly reckless disturbances of initial conditions?

        Understanding how it all fits together is a relatively new field called Earth system science. Earth system scientists work on building and fine-tuning mathematical models (computer programs) that describe the complex inter-relationships of Earth’s carbon, water, energy, and trace gases as they are exchanged between the terrestrial biosphere and the atmosphere.  Ultimately, they hope to understand Earth as an integrated system, and model changes in climate over the next 50-100 years.  The better the models, the more accurate and detailed will be the image in the crystal ball.

        NASA’s Earth System Science program provides real-world data for these models via a swarm of Earth-observing satellites.  The satellites, which go by names like Terra and Aqua, keep an eye on Earth’s land, biosphere, atmosphere, clouds, ice, and oceans.  The data they collect are crucial to the modelling efforts.

        Some models aim to predict short-term effects—in other words, weather.  They may become part of severe weather warning systems and actually save lives. Other models aim to predict long-term effects—or climate.  But, long-term predictions are much more difficult and much less likely to be believed by the general population, since only time can actually prove or disprove their validity.  After all, small errors become large errors as the model is left to run into the future.  However, as the models are further validated with near- and longer-term data, and as different models converge on a common scenario, they become more and more trustworthy to show us the future while we can still do something about it—we hope.

        For a listing and more information on each of NASA’s (and their partners’) Earth data-gathering missions, visit: science.nasa.gov/missions/earth.html

        Kids can get an easy introduction to Earth system science and play Earthy word games at: http://spaceplace.nasa.gov/ecosphere

 

 

 

CloudSat is one of the Earth-observing satellites collecting data that will help develop and refine atmospheric circulation models and other types of weather and climate models. CloudSat’s unique radar system reads the vertical structure of clouds, including liquid water and ice content, and how clouds affect the distribution of the Sun’s energy in the atmosphere.  See animation of this data simulation at:

www.nasa.gov/mission_pages/calipso/multimedia/cloud_calip_mm.html

 

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

 

 

 

 

 

 

CONTACTS

 

Chairman     John Vale-Taylor

                                                      pjvalet1@btinternet.com

 

Secretary & Events                 Phil Berry             01892 783544

                                                      philberryemail@gmail.com

 

 

Treasurer            Mike Wyles                          01892 542863

                                                      mike31@madasafish.com

 

Editor            Geoff Rathbone                         01959 524727

                                                      geoff@rathbone007.fsnet.co.uk

 

 

Director of Observations       Brian Mills    01732 832691

                                                      Brian@wkrcc.co.uk

 

Paul Treadaway                       01342 313799

                                                      paul_treadaway@btinternet.com

 

Wadhurst Astronomical Society website:

                                                      www.wadhurst.info/was/

 

SAGAS web-site                        www.sagasonline.org.uk

 

Any material for inclusion in the May 2012 Newsletter should be with the Editor by April 28th 2012