Comet ISON dies as it rounds the Sun Our star apparently destroyed this surprisingly fragile celestial visitor during their close encounter. By Richard Talcott | Published: Monday, December 02, 2013 Comet ISON (4.5 billion B.C. – A.D. 2013) survived for more than 4.5 billion years in the frigid depths of the solar system, but it fizzled during its brief moment in the Sun on November 28. Through a combination of ISON’s delicate makeup, the Sun’s intense heat, and — most importantly — our star ’s powerful tidal forces, the comet’s nucleus failed to survive its brush within 730,000 miles (1.16 million kilometers) of the Sun’s surface. As the comet approached perihelion (its least distance from the Sun) November 28, it continued to brighten at roughly the rate astronomers had predicted. Late on the evening of the 27th (in North America), ISON peaked at magnitude –2.0. Images from coronagraphs aboard both the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) showed the comet as a bright point of light trailed by one distinct dust tail and a narrow dust streamer. But ISON started to fade even before its closest approach to the Sun. The Solar Dynamics Observatory (SDO), which is equipped with the best cameras for close-up observations of our star and its surroundings, failed to see the comet at perihelion. And once ISON had moved far enough beyond the Sun that it could reappear in SOHO’s coronagraphs, it was nowhere to be found. As astronomers began to write their post-mortems, however, the unpredictable comet rose from the dead like the legendary Phoenix. Some 24 hours after perihelion, SOHO once again captured images of ISON showing a thin dusty tail and a diffuse central condensation that some interpreted as a small remnant of the comet’s nucleus. But the revival soon began to peter out — by late on November 29, the glow had faded to around 6th magnitude. It appears that the show amateur astronomers were hoping ISON would produce once it emerged from the Sun’s glare in early December won’t take place. Most scientists think the nucleus has dissipated, and any remaining dust likely will be too faint to see through anything but large telescopes. Even though ISON’s saga seems over, astronomers will spend months poring over their observations of this one-of-a-kind visitor. http://www.astronomy.com/news/2013/12/comet-ison-dies-as-it-rounds-the-sun -- $love = false; --

※ 发信站: 批踢踢实业坊(ptt.cc) ◆ From: 124.10.80.50 今年不管是ISON或是PANSTARRS (C/2011 L4) 都是在近期发现的,所以可以有生之年还是 令人值得期待啦! 百武似乎也是挺有趣的 3月25日，哈伯望远镜拍摄到百武彗星彗核物质分裂的样子[1]，同时地面天文爱好者亦拍 摄到此现象。3月26日至28日，美国和德国的天文学家使用伦琴X射线天文卫星（ROSAT） 发现彗星的X射线辐射，这是人类首次探测到彗星发射X射线，且其强度也是天文学家始料 不及的。百武彗星的X射线是在彗星内部形成还是太阳风与彗星物质的猛烈撞击还没有定 案。(from wiki) ※ 编辑: felaray 来自: 124.10.80.50 (12/04 16:36) ※ 编辑: felaray 来自: 124.10.80.50 (12/04 16:39) 当年的报导居然还在 如何观测哈雷彗星﹖——请听天文台长怎麽说 http://210.60.224.4/ct/content/1985/00110191/0009.htm ※ 编辑: felaray 来自: 124.10.80.50 (12/05 10:42)