Newsletter of the Stratford-upon-Avon Astronomical Society OCTOBER 2013

Double system actually a triple

The nearby star system – of special interest for its unusual exoplanet and dusty debris disk – has been discovered to be not just a double star, as astronomers had thought, but one of the widest triple known as a previously known smaller star in its vicinity is also part of the Fomalhaut system.

Eric Mamajek, Associate Professor of Physics and Astronomy at the University of Rochester, and his collaborators found the triple nature of the star system through a piece of detective work.

"I noticed this third star a couple of years ago when I was plotting the motions of stars in the vicinity of Fomalhaut for another study," Mamajek said. "However I needed to Map of the Fomalhaut triple system. is collect more data and gather a team of co- roughly 6 degrees away from Fomalhaut A! authors with different observations to test is the orangish K dwarf TW PsA. The age for this stellar MEETINGS: 7:30 for 8pm whether the star's properties are consistent trio appears to be consistent with ~440 million years. The with being a third member of the Fomalhaut arrows show the proper motion vectors for the stars. Due Club Nights include a variety of system." to the relative motions between the Fomalhaut trio and activities, including: observing topics, our , the positions of the stars are all moving at monthly sky notes, multimedia, By carefully analysing astrometric (precise approximately 0.4 arcseconds per year (taking about ~10,000 years to traverse a degree). astronomical chat and observing the movements) and spectroscopic night sky (weather permitting). measurements (that allow the temperature and radial velocity to be determined), the The researchers also had to show that it would October 15th researchers were able to measure the distance be feasible for these two stars to be “Cosmic Sirens: The Dawn of and speed of the third star. They concluded gravitationally bound, rather than moving Gravitational Astronomy” that the star, until recently known as LP 876-10, independently. "Fomalhaut A is such a massive (Prof Sathyaprakash) is part of the Fomalhaut system, making it star, about twice the mass of our Sun, that it Fomalhaut C. can exert sufficient gravitational pull to keep

November 5th "Fomalhaut C looks quite far apart from the this tiny star bound to it – despite the star Club Night: sky notes & observing big, bright star that is Fomalhaut A when you being 158,000 times farther away from (weather permitting) look up at the sky from Earth," added Fomalhaut than the Earth is from the Sun," Mamajek. There are roughly 5.5 degrees Mamajek said.

November 19th between the two stars, which is as if they were There are another 11 star systems closer to our “From Lobster's Eyes to Alien Oceans ” separated by roughly 11 full moons for an Sun than Fomalhaut that consist of three or (Dr Nigel Bannister) observer on Earth. Mamajek explained that more stars, including the closest star system, JUpiter ICy Moon Explorer (JUICE) ESA they look this far apart, in part, because Alpha Centauri. The new measurements also spacecraft to visit the Jovian system Fomalhaut is relatively close to Earth as stars show that the Fomalhaut system is the most go – approximately 25 light years. If these stars massive and widest among these nearby December 3rd were far away from Earth, they would appear multiple systems. Lecture night - tba much closer together in the sky. That they appear so far apart could explain why the Fomalhaut A is also the 18th brightest star January 7th - 2014 connection between LP 876-10 and Fomalhaut visible in our night sky and one of the few stars Club Night: sky notes & observing had been previously missed. Being able to with both a directly imaged exoplanet and a (weather permitting) obtain high quality astrometric and velocity dusty debris disk. The famous star has been data were the other keys. featured in science fiction novels by writers January 21st “Rings reign on Saturn” (tbc) (James O'Donoghue & Dr Henrik Melin)

February 4th - 2014 Club Night: sky notes & observing (weather permitting)

February 18th Lecture night - tba

March 4th Club Night: sky notes & observing (weather permitting)

March 18th “Volcanoes in the Solar System” (Dr Paul Olver)

www.astro.org.uk www.facebook.com/StratfordAstro www.twitter.com/StratfordAstro , Stanislaw Lem, Philip K. Dick, and . brightness to Polaris. The age of the trio is about 440 million years – roughly a tenth the age of our solar system. Despite being a well-studied system, it was only recently confirmed that Fomalhaut was a binary star – two stars that orbit each other – although it had been first suggested in the 1890s.

In 2006 a colleague of Mamajek, Prof Alice Quillen, predicted the existence of a planet around Fomalhaut, as well as the shape of its orbit, by trying to understand why the debris ring was off-centre and why it had a surprisingly sharp edge. The following year a new planet around Fomalhaut was imaged.

Many questions about Fomalhaut A's exoplanet and debris disk still remain unanswered. For example, astronomers are puzzled by why the exoplanet known as Fomalhaut "b" is on such an eccentric orbit and why the debris disk does not appear to be centred on the star Fomalhaut A. It is possible that Fomalhaut's wide companions B and C have gravitationally perturbed the Fomalhaut "b" exoplanet and debris belt orbiting Fomalhaut A, however the orbits of Fomalhaut's companion stars are not well-constrained. The orbits of Fomalhaut B and C around Fomalhaut A are predicted to take millions of years, so pinning down their orbits will be a challenge for future astronomers.

While Fomalhaut C is a star – the most common type of star in the universe – Fomalhaut B is an orange dwarf star about three-quarters the mass of our Sun. From the vantage point of a hypothetical planet orbiting Fomalhaut C, Fomalhaut A would appear to be a brilliant white star nine times brighter than Sirius (the brightest star in our night sky); similar to the typical brightness of the planet Venus. Notional sketch of the Fomalhaut system viewed face-on. The radial locations of features are Fomalhaut B would appear to be an otherwise approximate and not to scale e.g. the 10AU gelt represent dust near the 10AU radius but the unremarkable bright orangish star similar in width of the belt is not precisely known. (see http://arxiv.org/pdf/1305.2222v1.pdf)

And the winners are… The theory proposed by Englert and Higgs describes this process. On 4th July 2012, at the CERN laboratory for particle physics, the theory was confirmed by the discovery of a Higgs particle. CERN’s particle collider, LHC (Large Hadron Collider), is probably the largest and the most complex machine ever constructed by humans. Two research groups of some 3,000 scientists each, ATLAS and CMS, managed to extract the Higgs particle from billions of particle collisions in the LHC.

Even though it is a great achievement to have found the Higgs particle — the missing piece in the Standard Model puzzle — the Contacts Standard Model is not the final piece in Ian Galletly the cosmic puzzle. (Chair) [email protected] François Englert and Peter W. Higgs have been jointly awarded the One of the reasons Nobel Prize in Physics 2013 for the theory of how particles acquire for this is that the Richard Chubb mass. In 1964, they proposed the theory independently of each Standard Model (Vice Chair) other (Englert together with his now deceased colleague Robert treats certain [email protected] Brout). particles, neutrinos, as being virtually John Waller The theory is a central part of the Standard Model of particle physics massless, whereas (Membership & Treasurer) that describes how the world is constructed. According to the recent studies show [email protected] Standard Model, everything, from flowers and people to that they actually stars and planets, consists of just a few building Jim Dean do have mass. blocks: matter particles. These particles are governed (Events Secretary) by forces mediated by force particles that make sure Another [email protected] everything works as it should. reason is that the model only Julia Waller The entire Standard Model also rests on the existence of describes visible (Newsletter Editor & Secretary) a special kind of particle: the Higgs particle. This particle originates matter, which only [email protected] from an invisible field that fills up all space. Even when the universe accounts for one fifth seems empty this field is there. Without it, we would not exist, of all matter in the because it is from contact with the field that particles acquire mass. cosmos. Hanwell Community Observatory at Banbury Canal Open Day 2013

View of the gable end through the 6” reflector (inverted due to the properties of the optical On Sunday 6th October, as part of their system inside the telescope). outreach programme, members of Hanwell Community Observatory (HCO) took part in The HCO telescopes were set up in a part of the Open Day celebrations at Banbury Canal the canal known as Tooley’s Boatyard, which in the centre of Banbury. is the oldest working dry dock on the Inland Waterways. It has been in continuous use since 1790 and also boast a 200 year-old forge which is a Scheduled Ancient Monument and where you can learn to The modified solar telescope (Coronado PST + 6” blacksmith. Schmidt-Cassegrain)

www.HanwellObservatory.org.uk Matt’s heavy-duty German Equatorial Behind the HCO telescopes was a recently mounts are custom-made to order and erected green fibre-glass dome housing a intended to be housed within some sort of couple of 6” Schmidt-Cassegrain telescopes observatory. Matt has used CAD software to dedicated to solar observing on a prototype design them and then partnered with other mount designed by Matt Armitage who runs companies such as AWR Technology, Christopher Taylor, Ian Galletly, Oliver King Astromount Ltd as well as being a Director of Astroparts and Beacon Hill Telescopes to and Anne Sheppard were on hand to show Tooley’s Boatyard. He explained that he help him complete the finished product. people some wonderful views of our Sun became interested in astronomy a while ago through a variety of telescopes. The HCO and, as his hobby developed, he realised solar telescope, which is identical to that that he could use his skills to design and owned by our Society, was trained on a build a professional mount to meet his own number of impressive prominences and needs and that of other interested beside it was a refractor capped off with a astronomers. white-light solar filter looking at the few One of the dome’s telescopes views the Sun sunspots that graced the solar disc.

Prominences imaged through the Coronado solar telescope .

Sunspots imaged using the refractor capped with a solar filter. Matt Armitage (Astromount Ltd) inside the green Being so stable with GOTO technology and a Alongside these two telescopes was a 6” canalside dome with the two dedicated solar smooth drive system they can be used for reflector set up to look at the gable end of telescope and a prototype mount. astrophotography with all types of one of the canal-side buildings. Interestingly, telescopes including 6 to 10-inch refractors they had spotted a number of bees flying in in white light i.e. with a special filter on its and 12 to 20-inch Newtonians and and out of the end of the gable. Obviously front end. The other one views the solar disc Catadioptrics. (A catadioptric telescope these insects were taking advantage of some in a wavelength of light known as Hydrogen- combines both lenses and mirrors e.g. a sort of space in the structure but it was a alpha. Interestingly the latter is an unusual Schmidt-Cassegrain). good demonstration for visitors of the combination of two telescopes - a Coronado www.astromount.co.uk power and clarity of the telescope given the PST solar ‘scope and a 6” Schmidt- 07950 894203 lack of stars! Cassegrain.

Extra-terrestrial Plastic of all other gases around of more detailed analysis of the CIRS data. it. The detection of the NASA's Cassini spacecraft has detected "This measurement was very difficult to make chemical fills in a propylene (a chemical used to make food- because propylene's weak signature is mysterious gap in storage containers, car crowded by related chemicals with much Titan bumpers and other stronger signals," said observations consumer products) on Michael Flasar, that dates back Saturn's moon Titan. This Goddard scientist and to NASA's is the first definitive principal investigator Voyager 1 spacecraft and the detection of the plastic for CIRS. "This success first-ever close flyby of this ingredient on any moon or boosts our confidence moon in 1980. Voyager identified planet, other than Earth. that we will find still many of the gases in Titan's hazy more chemicals long A small amount of propylene brownish atmosphere as hidden in Titan's atmosphere." was identified in Titan's lower hydrocarbons, the chemicals that atmosphere by Cassini's primarily make up petroleum and Cassini's mass spectrometer, a composite infrared other fossil fuels on Earth. device that looks at the composition of spectrometer (CIRS). This Titan's atmosphere, had hinted earlier that On Titan, hydrocarbons form after instrument measures the infrared propylene might be present in the upper sunlight breaks apart methane, the light, or heat radiation, emitted from Saturn atmosphere. However, a positive second-most plentiful gas in that and its moons. Propylene is the first molecule identification had not been made. atmosphere. The newly freed fragments can to be discovered on Titan using CIRS. By link up to form chains with two, three or http://saturn.jpl.nasa.gov . isolating the same signal at various altitudes more carbons. The family of chemicals with within the lower atmosphere, researchers two carbons includes the flammable identified the chemical with a high degree of gas ethane. Propane, a common fuel Polypropylene is a confidence. for portable stoves, belongs to the plastic polymer with the "This chemical is all around us in three-carbon family. chemical formula C3H6. It is everyday life, strung together in used in many different Previously, Voyager found long chains to form a plastic called settings, both in industry and propane, the heaviest member polypropylene," said Conor Nixon, in consumer goods, and it can of the three-carbon family, and a planetary scientist at NASA's be used both as a structural propyne, one of the lightest Goddard Space Flight Center. "That plastic and as a fiber. This plastic is often used for members. But the middle chemicals, plastic container at the grocery store food containers, particularly those that need to be one of which is propylene, were with the recycling code 5 on the bottom -- dishwasher safe. The melting point of missing. As researchers continued to that's polypropylene." polypropylene is very high compared to many discover more and more chemicals in other plastics, at 320°F (160°C), which means that CIRS can identify a particular gas glowing in Titan's atmosphere using ground- the hot water used when washing dishes will not the lower layers of the atmosphere from its and space-based instruments, cause dishware made from this plastic to warp. unique thermal fingerprint. The challenge is propylene was one that remained to isolate this one signature from the signals elusive. It was finally found as a result

New Trojan asteroid discovered

Astronomers from the University of British Columbia (UBC) have discovered the first Trojan asteroid sharing the orbit of Uranus, and believe 2011 QF99 is part of a larger-than-expected population of transient objects temporarily trapped by the gravitational pull of the Solar System’s giant planets.

Trojans are asteroids that share the orbit of a planet, occupying stable positions known as Lagrangian points. Several temporary Trojans and co-orbitals have been discovered in the Solar System during the past decade. Astronomers considered their presence at Uranus unlikely because the gravitational pull of larger neighbouring planets would destabilize and expel any Uranian Trojans over the age of the Solar System.

To determine how the 60 km-wide ball of rock and ice ended up sharing an orbit with Uranus the astronomers created a simulation of the Solar System and its co-orbital objects, including Trojans.

“Surprisingly, our model predicts that at any given time three per Predicted motion of the temporary Trojan asteroid 2011 QF99 over the next cent of scattered objects between Jupiter and Neptune should be co- 59,000 years. Its current position is shown by the red square next to its designation. In the next 1 million years it will escape from Uranus’ gravity well orbitals of Uranus or Neptune,” says Mike Alexandersen from UBC. and rejoin the collection of planet-crossing Centaurs from which it originated. This percentage had never before been computed, and is much higher than previous estimates. how objects migrate into the planetary region of the Solar System.”

QF99 is one of those temporary objects, that only recently (within Centaurs are small Solar System bodies whose orbits take them out the last few hundred thousand years) has been ensnared by Uranus to a region between those of the outer planets. They have unstable and is set to escape the planet’s gravitational pull in about a million orbits that cross or have crossed the orbits of one or more of the years. giant planets, and typically last for a few million years. Named after a

“This tells us something about the current evolution of the Solar mythological race of beings that were a half horse half human, it has System,” says Alexandersen. “By studying the process by which been estimated that there are around 44,000 centaurs in the Solar Trojans become temporarily captured, one can better understand System with diameters larger than 1 km.