The SOCIETY for POPULAR ASTRONOMY
Electronic News Bulletin No. 362 2013 October 13
Here is the latest round-up of news from the Society for Popular
Astronomy. The SPA is Britain's liveliest astronomical society, with members all over the world. We accept subscription payments online at our secure site and can take credit and debit cards. You can join or renew via a secure server or just see how much we have to offer by visiting http://www.popastro.com/ CURIOSITY FINDS WATER ON MARS NASA
Curiosity landed in Gale Crater on the surface of Mars on 2012 Aug. 6.
There was hope that it could throw light on the question: "Could Mars have once harboured life?" To do that, Curiosity carried equipment (grandiosely entitled the 'Sample Analysis at Mars (SAM) instrument suite'), which includes a gas chromatograph, a mass spectrometer and a tuneable laser spectrometer) for gathering and processing samples of rock and soil. Those tools enable SAM to identify a wide range of chemical compounds and determine the ratios of different isotopes of key elements. By combining analyses of water and other volatiles from SAM with mineralogical, chemical and areological data from Curiosity's other instruments, we have made some progress in understanding surface processes and the action of water on Mars. Operators used the rover's scoop to shovel up dust, dirt and finely grained soil from a sandy patch. They fed portions of the fifth scoop into SAM, where the 'fines' -- dust, dirt and fine soil -- were heated to 835C. Baking the sample also indicated a compound containing chlorine and oxygen, probably chlorate or perchlorate such as had previously found near the north pole on Mars. Finding such compounds also at Curiosity's equatorial site suggests that they might be distributed more globally. The analysis also suggests the presence of carbonate materials, which form in the presence of water.
In addition to determining the amount of the major gases released, SAM
also analyzed ratios of isotopes of hydrogen and carbon in the released water and carbon dioxide. Isotopes are variants of the same chemical element (so with the same numbers of protons in the nuclei) with different numbers of neutrons, and therefore different atomic weights. SAM found that the ratio of some isotopes in the soil is similar to the ratio found in atmospheric samples analyzed earlier, indicating that the surface soil has interacted heavily with the atmosphere. The isotopic ratios, including hydrogen-to-deuterium ratios and carbon isotopes, tend to support the idea that as the dust is moved around the planet, it reacts with some of the gases from the atmosphere. SAM can also search for trace levels of organic compounds. Although several simple organic compounds were detected in the experiments, they are not clearly Martian in origin. Instead, it is likely that they formed during the high-temperature experiments, when the heat decomposed perchlorates in the samples, releasing oxygen and chlorine that then reacted with terrestrial organics already present in the SAM instrument. SAM can perform another kind of experiment to address the question of whether organic molecules are present in the Martian samples. The SAM suite includes nine fluid- filled cups which hold chemicals that can react with organic molecules if such are present in the soil samples. The combined results could shed light on the composition of the planet's surface, and may offer direction for future research.
FOMALHAUT IS A TRIPLE STAR
University of Rochester.
The 'nearby' star system Fomalhaut -- of special interest for its
unusual exoplanet and dusty debris disc -- has been discovered to be not just a double star, as astronomers had thought, but one of the widest triple stars known. By carefully analyzing astrometric (precise movements) and spectroscopic measurements (that allow the temperature and radial velocity to be determined), researchers were able to measure the distance and motion of the third star. They concluded that the star, until recently known as LP 876-10, is part of the Fomalhaut system, making it Fomalhaut C. Fomalhaut C appears a long way from the big, bright star that is Fomalhaut A. The stars are about 5.5 degrees apart, which goes a long way towards explaining why the connection between LP 876-10 and Fomalhaut had previously been overlooked; the high-quality astrometric and velocity data were the key. The researchers also needed to show that it would be feasible for the two stars to be gravitationally bound together, rather than moving independently. Fomalhaut A is such a massive star, about twice the mass of our Sun, that it can keep its tiny companion bound to it. despite their separation of 158,000 astronomical units (Earth--Sun distances). The team had already gathered several years of observations on the companion star with the SMARTS 0.9-m telescope at Cerro Tololo in Chile. The radial velocity of the star was measured by observers from the University of Chicago and proved to be within about 1 km/s of that of Fomalhaut A.
There are 11 star systems closer to us than Fomalhaut that consist of
three or more stars, including the closest star system of all, Alpha Centauri. The new measurements show that the Fomalhaut system is the most massive and widest among these 'nearby' multiple systems. Fomalhaut A is the 18th-brightest star, and is one of the few stars that have both a directly-imaged exo-planet and a dusty debris disc, but it was only recently confirmed that Fomalhaut was a binary star although that had first been suggested in the 1890s. Many questions remain about Fomalhaut A's exo-planet and debris disc, such as why the planet is in such an eccentric orbit and why the debris disc does not appear to be centred on the star A. It is possible that Fomalhaut's wide companions B and C have perturbed the planet and debris belt orbiting A; however, the orbits of the companion stars are not well-constrained -- the orbits of B and C around A probably take millions of years, so they cannot be determined accurately at all soon. While C is a red-dwarf star -- the most common type in the Universe -- B is an orange-dwarf star about 3/4 the mass of the Sun. From the vantage point of a hypothetical planet orbiting C, A would appear to be a brilliant white star about as bright as Venus appears to us. B would appear to be an otherwise unremarkable bright orangish star similar in brightness to Polaris. The age of the trio is about 440 million years -- roughly a tenth of the age of the Solar System. FIRST CLOUD MAP OF EXO-PLANET NASA
Astronomers using data from the Kepler and Spitzer space telescopes
have created the first cloud map of a planet beyond our Solar System, a Jupiter-like object known as Kepler-7b. The planet has high clouds in the west and clear skies in the east. Previous studies from Spitzer have resulted in temperature maps of planets orbiting other stars, but this is the first look at cloud structures. After observing for three years, astronomers were able to produce a very-low-resolution 'map' of the giant, gaseous planet. They would not expect to see oceans or continents on such a planet, but they interpreted the observations in terms of clouds. Visible-light observations of Kepler-7b's moon-like phases led to a rough map of the planet that showed a bright spot on its western hemisphere, but they were not enough on their own to decipher whether the bright spot was coming from clouds or heat. However, the Spitzer space telescope, observing in the infrared, was able to measure Kepler-7b's temperature, estimating it to be between 1,100 and 1,300 Kelvin. That is relatively cool for a planet that orbits so close to its star -- within 0.06 AU -- and was considered by the astronomers to be too cool to be the source of light that Kepler observed. Instead, they think it was light from the star, refelcted from cloud tops on the west side of the planet. Kepler-7b reflects much more light than most giant planets so far discovered, and astronomers attribute that to clouds in the upper atmosphere. The cloud patterns on the planet do not seem to change much over time -- it has a remarkably stable climate. The findings are an early step towards using similar techniques to study the atmospheres of planets more like the Earth in composition and size. ASTRONOMERS DISCOVER DENSEST GALAXY Michigan State University
An international team of astronomers has found a galaxy so dense that
as many as 10,000 stars are crammed into the space of 4 light-years or the distance between the Sun and Alpha Centauri. That galaxy is more massive than any ultra-compact dwarfs of comparable size and is arguably the densest galaxy known in the local Universe. It is in the Virgo cluster of galaxies, about 54 million light years away. What makes the galaxy, called M60-UCD1, so remarkable is that about half of its mass is found within a radius of only about 80 light-years. making the density of stars about 15,000 times greater than found in our neighbourhood in the Milky Way. Another intriguing aspect of the galaxy is the presence of a bright X-ray source in its centre, possibly a black hole 10 million times the mass of our Sun. The discovery of ultra-compact galaxies is relatively new -- only within the past 10 years or so. Until then, astronomers could see such objects but assumed that they were either single stars or very-distant galaxies.
Astronomers are trying to determine if M60-UCD1 and other ultra-compact
dwarf galaxies are either born as really jam-packed star clusters or if they are galaxies that get smaller because they have stars ripped away from them. The possible massive black hole, combined with the high galaxy mass and Sun-like levels of elements found in the stars, favour the latter idea. A giant black hole at the centre of M60-UCD1 helps tip the scales against the picture in which that galaxy was once a star cluster, since such large black holes are not found in such objects.
FINAL ANTENNA DELIVERED TO ALMA
ESO
The 66th and final antenna for the Atacama Large Millimetre/sub-
millimetre Array (ALMA) project has been handed over. The 12-m- diameter dish was manufactured by the European AEM Consortium and also marks the successful delivery of a total of 25 European antennae -- the largest ESO contract so far. North America has provided 25 12-m antennae, while East Asia has delivered 16 (four 12-m and twelve 7-m). By the end of 2013, all 66 dishes are expected to be working together as one telescope, in an array that will stretch for up to 16 kilometres across the Chajnantor Plateau in the Atacama Desert of northern Chile. Radiation at the wavelengths observed by ALMA comes from some of the coldest, but also from some of the most distant, objects, including cold clouds of gas and dust where new stars are being born, and remote galaxies towards the edge of the observable Universe. The Universe is relatively unexplored at sub-millimetre wavelengths, as the telescopes need extremely dry atmospheric conditions, many large antennae and advanced detectors. Even before completion ALMA has already been used extensively for scientific projects and has shown great potential.
PROPYLENE FOUND IN SPACE
NASA
The Cassini spacecraft has detected propylene, a chemical used to make
food-storage containers, car bumpers and other products, on Saturn's moon Titan. This is the first definitive detection of propylene otherwise than on Earth. A small amount of propylene was identified in Titan's lower atmosphere by Cassini's 'Composite Infrared Spectrometer' (CIRS). That instrument measures the infrared light, or heat radiation, emitted from Saturn and its moons in much the same way our hands feel the warmth of a fire. Propylene is the first molecule to be discovered on Titan by CIRS. By isolating the same signal at various altitudes within the lower atmosphere, researchers identified the chemical with a high degree of confidence. CIRS can identify a particular gas glowing in the lower layers of the atmosphere from its unique thermal fingerprint. The challenge is to isolate the one signature from the signals of all other gases around it.
Voyager 1, which flew past Titan in 1980, identified many of the gases
in Titan's hazy brownish atmosphere as hydrocarbons, the chemicals that primarily make up petroleum and other fossil fuels on Earth. On Titan, hydrocarbons form after sunlight breaks apart methane, the second-most plentiful gas in that atmosphere. The newly freed fragments can link up to form chains with two, three or more carbon atoms. The family of chemicals with two carbon atoms includes the inflammable gas ethane. Propane, a common fuel for portable stoves, belongs to the three-carbon family. Voyager detected all members of the one- and two-carbon families in Titan's atmosphere. From the three-carbon family, the spacecraft found propane, the heaviest member, and propyne, one of the lightest members. But the middle chemicals, one of which is propylene, were missing. As researchers continued to discover more and more chemicals in Titan's atmosphere with ground- and space-based instruments, propylene was one that remained elusive. It was finally found as a result of more careful analysis of the CIRS data. SPACECRAFT GOES INTO LUNAR ORBIT Spaceweather.com
Among the few people allowed to work during the US government
shutdown, controllers for NASA's 'Lunar Atmosphere and Dust Environment Explorer' (LADEE) fired the spacecraft's engines on Oct. 6, slowing it enough to be captured by lunar gravity. LADEE is now in orbit round the Moon. Soon, the spacecraft will begin its mission to study the Moon's exotic and diaphanous atmosphere, which is very much affected by space weather. PLANCK TELESCOPE SET FOR SWITCH-OFF BBC News
The process of disposing of the Planck space telescope has begun. The
satellite, which mapped the "oldest light" in the Universe in unprecedented detail, has completed its mission and will be turned off in a fortnight's time. It is currently a million miles from the Earth, and is undergoing some final engineering tests. European Space Agency controllers will initiate a big burn on Planck's thrusters, pushing it away from the planet into a separate orbit. A second burn on 21 October will run the satellite's propellent supply to exhaustion. The batteries will be disconnected and the transmitters switched off. Final contact is scheduled for 23 October, and Planck will just drift off. Planck has returned a great deal of information, recording thousands of objects in the sky not previously recognised. But its main quest was to survey the Cosmic Microwave Background (CMB) -- the "first light" to be emitted once a post-Big-Bang Universe had cooled sufficiently to permit the formation of hydrogen atoms. Before that time, scientists say, the cosmos would have been so hot that matter and radiation would have been 'coupled' - the Universe would have been opaque.
Bulletin compiled by Clive Down
(c) 2013 the Society for Popular Astronomy
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Good Clear Skies
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Astrocomet
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Colin James Watling
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Astrocomet
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Colin James Watling
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Various Voluntary work-Litter Picking for Parish Council (Daytime) and also a friend of Kessingland Beach (Watchman)
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Profile: http://www.google.com/profiles/astrocomera
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Lyra Website: https://sites.google.com/site/lyrasociety/
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Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
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Information
Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
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Information
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