*********************************** The SOCIETY for POPULAR ASTRONOMY *********************************** ==================================================== Electronic News Bulletin No. 282 2010 February 14 ==================================================== 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/ FIREBALLS LATEST By Alastair McBeath, SPA Meteor Section Director French meteor analyst Karl Antier has reported to us that a magnitude -8 or so fireball was seen from places across western and northern France on January 24-25 at 20:51 UT. It was also caught on video, as can be seen via the link at:http://snipurl.com/ucps2 . The fireball was observed in the southern sky from Le Havre, so it is possible the meteor might have been spotted, probably low to very low in the sky, from southern England. As yet, no comparable UK reports have been received, however. More recently, somewhat confused reports have come through, suggesting possibly up to three separate fireballs were seen from Ireland and/or Northern Ireland before 20h UT on February 3-4. Much of this news came from media reports, suggesting there were "hundreds" of sightings, though so far, very few usable observations have been submitted to the Section. Of those sufficiently detailed to tell, one report each from around 17:55-18:00 UT has arrived from Co Armagh in Northern Ireland, and a little south of Dublin's city centre in the Irish Republic. The Co Armagh observer saw the object in the northwest to north-northwest sky, while the near-Dublin observer saw the fireball pass behind buildings to the north-northeast, at a similar elevation above the horizon to what the Armagh witness reported for the meteor's start. If correct, these positions show the sightings must have been of different meteors. That might suggest there were two fireballs, one off northwest Ireland/Northern Ireland, the other off northeast Northern Ireland/ Ireland, the neighbouring Irish Sea, or adjacent parts of western Britain, around ~18h. A further fireball, seen from parts of Ireland around 19:30-19:40, was reported as apparently fainter than the earlier meteor(s), but almost no information other than this has reached the Section about it as yet. For the media weblinks and further discussion, see topics on the SPA's Observing Forum topic at: http://snipurl.com/ucsif ,and the UK Weather World's Space Weather Forum at: http://snipurl.com/ucsim . Claims of a video recording of the ~18h fireball have proven false, as this was imaged in 2008 apparently, and in some places online, it seems to have been shown in reverse anyway. As February 14 is both Chinese New Year and St Valentine's Day, a fresh wave of sky-lantern sightings mistaken for meteors and fireballs (see most recently ENB 280,http://snipurl.com/ucps9 ) doubtless can be expected. The increasing, and deadly, threat these pose to animals, particularly agricultural livestock, once spent and littered across the countryside, has been especially highlighted in the last couple of weeks, with Baroness Fookes in the House of Lords asking what steps the UK government proposes to take regarding this risk. See http://snipurl.com/ucqjc on the General Chat Forum for more, particularly Assistant Meteor Director David Entwistle's February 6 posting, which contains a link to the original parliamentary transcript. Any fresh sightings of genuinely meteoric fireballs seen from the UK and nearby, whether of the January 24-25 and February 3-4 events or not, would be welcomed by the Meteor Section. See the "Making and Reporting Fireball Observations" page of the SPA website, at: http://snipurl.com/u8aer , for details of what information to send, and where to. PLANETS By Andrew Robertson, SPA Planetary Section Director. As per my previous e-bulletins, Mars is still the favourite. It reduces in size from 13" to 12" over the next 2 weeks but culminates at 10pm with an altitude of 61 degrees mid period so is at it's optimum for observation by those who have to get up for work the next day. I of course don't but am being thwarted by cloud living close to the East coast of East Anglia. However I'm now getting a glut of images and sketches from members taken through a spell of good seeing with corresponding excellent results so....get on Mars while you can. I look forward to receiving your reports. Additionally Richard McKim, BAA Mars director circulated a bulletin about a brief dust storm that appeared over the NPC (North Polar Cap) for a few days (now subsided) around about 29th to 31st Jan that were captured on amateur images. Always something happening with Mars. Saturn culminates about 2am at an altitude of 38 degrees (From my latitude of 52.5 degs North) with a tilt of 4 degrees. So again, for those with larger telescopes worth looking out for shadow transits of it's larger moons although Titan is not in the frame for this currently. The minor planet Vesta reaches opposition on 18th Feb at Mag 6.1 whilst in Leo. Various magazines give charts for this. On the evenings of Tue 16th & Wed 17th there is a close conjunction (less than 0.8 degs apart) between Venus and Jupiter - always a spectacular sight. However they are only 8 degrees from the Sun so you need to wait until the Sun has set before looking for them after which they will be just 5 degrees above the horizon. From my location the Sun sets about 1710 hours and I can't stress enough that you MUST NOT look at the Sun through a Telescope or Binoculars or permanent blindness could result! Hence my stating, 'wait until the Sun has set.' You will need a clear horizon to the WSW. SUSPECTED ASTEROID COLLISION NASA The Hubble telescope has observed an asteroid associated with an unusual debris pattern and trailing streamers of dust that suggest a collision between two asteroids. Astronomers have long thought that the asteroid belt is being ground down through collisions, but no evidence has been seen previously of a recent collision. An object called P/2010 A2 was discovered by the LINEAR sky survey on January 6. At first, astronomers thought it might be a so-called 'main-belt comet' -- a rare case of a comet orbiting in the asteroid belt. Follow-up images taken by Hubble on January 25 and 29, however, revealed a complex X-pattern of filamentary structures near the nucleus. Hubble shows the main nucleus of P/2010 A2, estimated to be 140 m across, to lie outside its own halo of dust. Normal comets are thought to fall into the inner regions of the Solar System from distant reservoirs and, as they approach the Sun and warm up, ice near the surface vaporizes and ejects material from the solid nucleus by jets. But the debris round P/2010 A2 may have a different origin. The asteroid orbits within the asteroid belt where its nearest neighbours are dry rocky bodies lacking volatile materials. It seems possible that the complex debris tail is the result of an impact between two bodies, rather than ice simply volatilizing from a parent body. If that interpretation is correct, two small and previously unknown asteroids recently collided, creating a shower of debris that is being swept back into a tail from the collision site by the pressure of sunlight. The main nucleus of P/2010 A2 would be the surviving remnant of the collision. The asteroid belt contains abundant evidence of ancient collisions that have shattered precursor bodies into fragments. The orbit of P/2010 A2 is consistent with membership in the Flora asteroid family, produced by collisional shattering more than 100 million years ago. ASTRONOMERS DISCOVER COOL STARS IN NEARBY SPACE RAS Astronomers using the United Kingdom Infrared Telescope (UKIRT) in Hawaii have discovered what may be the coolest sub-stellar body so far found outside the Solar System. It has very peculiar colours, which make it appear either very blue or very red, depending on which part of the spectrum is considered. The object is known as SDSS1416+13B and is in a large orbit around a somewhat brighter and warmer brown dwarf, SDSS1416+13A. The pair is between 15 and 50 light-years away. The brighter member was detected in visible light by the Sloan Digital Sky Survey, but SDSS1416+13B is seen only in infrared light. SDSS1416+13B was first noticed as part of a dedicated search for cool brown dwarfs by UKIRT. The object appeared far bluer at near-infrared wavelengths than any brown dwarf seen before. A near-infrared spectrum taken with the Japanese Subaru telescope in Hawaii showed that it is a type of brown dwarf called a T dwarf, which has a lot of methane in its atmosphere, but with peculiar spectral features including a big gap at a certain wavelength. Astronomers soon noticed that a previously observed brighter star (SDSS1416+13A) close by is also a brown dwarf. They then used the orbiting Spitzer telescope to investigate SDSS1416+13B at mid-infrared wavelengths, which are thought to be the most reliable indicator of temperature, and found that it is the reddest known brown dwarf at those wavelengths by some margin. Comparison with theoretical models of brown-dwarf atmospheres has provided a temperature estimate of 500 K. UNUSUAL SUPERNOVA EXPLOSION Science Daily For the first time, astronomers have found a supernova explosion with properties similar to a gamma-ray burst, but without seeing any gamma- rays from it. Radio observations made with the VLA showed that material was expelled from the supernova explosion SN2009bb at speeds approaching that of light. That characterized the supernova, first seen last March, as the type thought to produce one kind of gamma-ray burst. When the nuclear-fusion reactions at the cores of very massive stars can no longer provide the energy needed to hold the core up against the weight of the rest of the star, the core collapses catastrophically into a super-dense neutron star or black hole. For reasons not easy to explain in simple terms, the rest of the star's material is blasted into space in a supernova explosion. Astronomers have identified one particular type of such 'core-collapse supernovae' as the cause of one kind of gamma-ray burst. Only about one out of a hundred supernovae of that type, however, produces a gamma-ray burst. In the more-common type of supernova, the explosion blasts the star's material outward in a roughly spherical pattern at speeds of 'only' about 3% of that of light, whereas in the supernovae that produce gamma-ray bursts, some, but not all, of the ejected material is accelerated to nearly the speed of light. Such extreme speeds are thought to be caused by an 'engine' in the centre of the supernova explosion, in which material falling toward the core enters a swirling 'accretion disc' surrounding the new neutron star or black hole. The disc produces -- still by processes hard to explain -- jets of material boosted to tremendous speeds from the poles of the disc. Until now, no such 'engine-driven' supernova had been found by any other means than by detecting gamma-rays emitted by it. The VLA radio telescope is soon to be upgraded, and some of the more optimistic astronomers hope in the future to find more such supernovae through radio observations than with gamma-ray satellites. One important question still to be answered is just what causes the difference between the ordinary supernovae and the 'engine-driven' ones. BRITAIN WITHDRAWS FROM CASSINI MISSION BBC News While the Cassini mission to Saturn is so successful that NASA has just extended it by seven years, British participation is to end because a government funding agency has withdrawn support. Scientists who work on Cassini say that the decision by the Science and Technology Facilities Council (STFC) will damage British astronomy severely. They accuse the agency of breaking international partnerships and jeopardising British involvement in future missions, just to save about #700,000 a year. The Cassini mission, which reached Saturn in 2004, is transforming understanding of the planet and its rings and moons. British scientists are involved in operating five of its instruments and processing their observations. However, the STFC, which has a budget shortfall of #115 million, identified further support as a low priority. The cuts also threaten a significant British role in future missions. A spokesman for the STFC said that tight financial budgets had forced unpalatable but necessary choices to be made to wind down, or to withdraw from, some projects. Bulletin compiled by Clive Down (c) 2010 the Society for Popular Astronomy The Society for Popular Astronomy has been helping beginners to amateur astronomy -- and more experienced observers -- for more than 50 years. If you are not a member then you may be missing something. Membership rates are extremely reasonable, starting at just #16 a year in the UK. 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