Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://star.arm.ac.uk/nibulletin/2006/Nov-13.html
Дата изменения: Tue Nov 14 12:44:05 2006 Дата индексирования: Tue Oct 2 04:13:57 2012 Кодировка: Поисковые слова: astro-ph |
![]()
From: TerryMosel@aol.com Date: 13 November 2006 22:08:17 GMT Subject: IAA Lecture, Leonids, Astronomy news, Hi all, 1. IAA Lecture: The next IAA public lecture will be by Deirdre Kelleghan, President of the IAS, on Wednesday 15 November, in Stranmillis College, Stranmillis Road, Belfast. The title will be "JPL's Robot Explorers" and it will look at some of the amazing spacecraft of the USA's Jet Propulsion Laboratory, which are exploring the Solar System. It's at 7.30 p.m., admission free, including light refreshments, and all are welcome. 2. LEONIDS: Don't forget the 'normal' Leonids maximum on Nov 17. This shower is active between 15 and 20 November each year, and produces respectable activity even in those years when no storm activity is expected. In 2006, the regular maximum should occur around Nov 17d 23h UT, with a ZHR of about 15 if we are lucky. Then there's the brief intense burst expected early on Nov 19, as already notified, but repeated here for convenience: BRIEF HIGH LEONID ACTIVITY for Nov 19? Dr David Asher of Armagh Observatory calculates that we may have a brief period of much enhanced meteor activity from the Leonids on the morning of 19 November. David has a great track record of predicting activity from particular filaments of material within the overall Leonid meteor stream, usually getting the time of peak activity right to within 5-10 minutes, which is remarkable! The Leonids are associated with comet Tempel-Tuttle, and are just about the fastest of all known meteor showers, as they collide with the Earth almost head-on, with entry speeds of around 250,000 kph. Thus they are very swift, and rarely last for more than 0.5 seconds (although the 'trains' they leave behind can last for many seconds, or even some minutes). The radiant, or point in the sky from which the meteors appear to come, lies in the East side of the 'Sickle of Leo'. The normal Zenithal Hourly Rate for the Leonids is only about 10 - 15, but they have also produced the greatest meteor showers - or 'storms' on record! The comet has a period of about 33 years, and much higher than normal rates therefore tend to occur about every 33 years or so, when Earth encounters the densest part of the stream of particles released by the comet each orbit. For example, there were displays of about 250-300 per hour in 1998, 3,700 p/h in 1999, and about 480 p/h in 2000. But the greatest display of all in modern times was in 1966, when they produced an astonishing rate of about 140,000 p/h for a brief period as seen from Western USA! We don't expect anything like that at all this year, but David predicts that we might get a ZHR of about 120 during a brief period at around 04.45 (+/- 10 minutes), on Nov 19. 3. SPITZER AND HUBBLE CREATE COLORFUL MASTERPIECE NASA's Spitzer and Hubble Space Telescopes have teamed up to expose the chaos that baby stars are creating 1,500 light-years away in the Orion nebula. This striking infrared and visible-light composite indicates that four monstrously massive stars at the center of the nebula may be the main culprits in the familiar Orion constellation. Link 4. GRAVITY HELPS REVEAL A JEWEL OF THE EARLY UNIVERSE A team from the Sloan Digital Sky Survey and Fermi National Accelerator Laboratory has announced discovery of the brightest known image of a galaxy from the early universe. While furious star formation makes the galaxy luminous, it enters the record books because the gravity of a foreground galaxy acts as a gravitational lens, focusing its light on the earth. Link 5. EARLY EARTH'S HAZE MAY HAVE SPURRED LIFE, STUDY SAYS Hazy skies on early Earth could have provided a substantial source of organic material useful for emerging life on the planet, according to a new study led by the University of Colorado at Boulder. The laboratory experiment modeled conditions measured by the Huygens probe on Saturn's moon, Titan. Link 6. MONSTER STELLAR FLARE DWARFS ALL OTHERS SEEN Scientists using NASA's Swift satellite have spotted a stellar flare on a nearby star so powerful that, had it been from our sun, it would have triggered a mass extinction on Earth. The flare was perhaps the most energetic magnetic stellar explosion ever detected. Link Clear skies, Terry Moseley
Last Revised: 2006 November 14th
WWW contact:webmaster@arm.ac.ukGo to HOME Page