从地面望远镜看来,所谓的“蚂蚁星云”(Menzel 3或者Mz3)似乎是一只普通蚂蚁的头部和胸部。这张由哈勃拍摄的生动照片将星云放大了十倍,显示了“蚂蚁”的身体实际上是一个死亡中的类日恒星突出的炽热抛出物。




  一种可能性是Mz3中心的恒星有一个很近的伴星,这个伴星有着很强的潮汐力,将外流的气体成为特殊形状。那么这个伴星必须离这颗即将死亡的恒星很近,大约是地球到太阳的距离。在那个距离上,伴星不会离恒星抛出的外壳很远。甚至恒星可能已经吞食了它的伴星,而伴星就在恒星的里面运行着,似乎是《彼得和狼》(Peter and the Wolf)中的狼肚子里的那只鸭子。



  1997年7月,天文学家Bruce Balick(华盛顿综合大学)和Vincent Icek(莱顿大学)用哈勃的宽视场行星照相机2观察了Mz3。一年后,加州喷气推进实验室的天文学家Raghwendra Sahai和John Trauger用一些稍不同的滤光器拍下了Mz3的一些照片。这张有意思的照片是由哈勃Heritage小组制作的,它是从两个数据集中分别选出的数个滤光器的合成物。


   译自 摘自哈勃网站(http://oposite.stsci.edu

Astro-Entomology? Ant-like Space Structure Previews Death of Our Sun
Chinese Version

  From ground-based telescopes, the so-called "ant nebula" (Menzel 3, or Mz3) resembles the head and thorax of a garden-variety ant. This dramatic NASA/ESA Hubble Space Telescope image, showing 10 times more detail, reveals the "ant's" body as a pair of fiery lobes protruding from a dying, Sun-like star. 

  The Hubble images directly challenge old ideas about the last stages in the lives of stars. By observing Sun-like stars as they approach their deaths, the Hubble Heritage image of Mz3 -- along with pictures of other planetary nebulae -- shows that our Sun's fate probably will be more interesting, complex, and striking than astronomers imagined just a few years ago. 

  Though approaching the violence of an explosion, the ejection of gas from the dying star at the center of Mz3 has intriguing symmetrical patterns unlike the chaotic patterns expected from an ordinary explosion. Scientists using Hubble would like to understand how a spherical star can produce such prominent, non-spherical symmetries in the gas that it ejects. 

  One possibility is that the central star of Mz3 has a closely orbiting companion that exerts strong gravitational tidal forces, which shape the outflowing gas. For this to work, the orbiting companion star would have to be close to the dying star, about the distance of the Earth from the Sun. At that distance the orbiting companion star wouldn't be far outside the hugely bloated hulk of the dying star. It's even possible that the dying star has consumed its companion, which now orbits inside of it, much like the duck in the wolf's belly in the story "Peter and the Wolf." 

  A second possibility is that, as the dying star spins, its strong magnetic fields are wound up into complex shapes like spaghetti in an eggbeater. Charged winds moving at speeds up to 1000 kilometers per second from the star, much like those in our Sun's solar wind but millions of times denser, are able to follow the twisted field lines on their way out into space. These dense winds can be rendered visible by ultraviolet light from the hot central star or from highly supersonic collisions with the ambient gas that excites the material into florescence. 

  No other planetary nebula observed by Hubble resembles Mz3 very closely. M2-9 comes close, but the outflow speeds in Mz3 are up to 10 times larger than those of M2-9. Interestingly, the very massive, young star, Eta Carinae, shows a very similar outflow pattern. 

  Astronomers Bruce Balick (University of Washington) and Vincent Icke (Leiden University) used Hubble to observe this planetary nebula, Mz3, in July 1997 with the Wide Field Planetary Camera 2. One year later, astronomers Raghvendra Sahai and John Trauger of the Jet Propulsion Lab in California snapped pictures of Mz3 using slightly different filters. This intriguing image, which is a composite of several filters from each of the two datasets, was created by the Hubble Heritage Team.

   Copied From Hubble Web(http://oposite.stsci.edu