The Helix Nebula

螺旋星云

NGC 7293: The Helix Nebula

"Will our Sun look like this one day? The Helix Nebula is the closest example of a planetary nebula created at the end of the life of a Sun-like star. The outer gasses of the star expelled into space appear from our vantage point as if we are looking down a helix. The remnant central stellar core, destined to become a white dwarf star, glows in light so energetic it causes the previously expelled gas to fluoresce. The Helix Nebula, given a technical designation of NGC 7293, lies about 650 light-years away towards the constellation of Aquarius and spans about 2.5 light-years. The above picture is a composite of newly released images from the ACS instrument on the Hubble Space Telescope and wide-angle images from the Mosaic Camera on the WIYN 0.9-m Telescope at Kitt Peak National Observatory. A close-up of the inner edge of the Helix Nebula shows complex gas knots of unknown origin."(NASA description)

我们的太阳将来会看起来像这样吗？Helix星云是离我们最近的一个行星状星云，它是在太阳类似恒星生命末期形成的。恒星向外喷射的气体从我们的视角看，就像我们正从螺旋的上方观察一样。残留的恒星核心，注定会成为一颗白矮星，发出的能量使之前喷射出的气体发出荧光。Helix星云，正式名称为NGC 7293，位于水瓶座方向，距离大约650光年，跨度约2.5光年。上述图片是来自哈勃空间望远镜上的ACS仪器和WIYN 0.9米望远镜在 Kitt Peak 国家天文台的宽角相机新发布的图像的合成图。Helix星云内边缘的特写显示了复杂且来源未知的气体团块。

Credit: NASA, WIYN, NOAO, ESA, Hubble Helix Nebula Team, M. Meixner (STScI), & T. A. Rector (NRAO)

注：NASA, WIYN, NOAO, ESA, 漩涡星云团队, M. Meixner (STScI), & T. A. Rector (NRAO)

Spitzer image of Helix Nebula

A striking feature of the Helix, first revealed by ground-based images, is its collection of thousands of filamentary structures, or strands of gas. In this image the filaments can be seen under the transparent blue gas as red lines radiating out from the center. Astronomers believe that the molecules in these filaments are able to stay cooler and more stable because dense clumps of materials are shielding them from ultraviolet radiation. This image is a composite showing ionized H-alpha (green) and O III (blue) gases from the Hubble Space Telescope, and molecular hydrogen (red) from the Spitzer Space Telescope observations at 4.5 and 8.0 microns.

螺旋的一个显著特征，最初通过地面观测图像揭示出来，是其成千上万的丝状结构，或气体丝。在这一图像中，这些丝状结构可以在透明的蓝色气体中看到，以红色线条从中心向外辐射。天文学家认为，这些丝状结构中的分子能够保持较冷和稳定，是因为密集的物质团在保护它们免受紫外线辐射。这张图像是一个合成图像，显示了哈勃太空望远镜拍摄的离子化H-α（绿色）和O III（蓝色）气体，以及斯皮策太空望远镜在4.5和8.0微米波长下观测到的分子氢（红色）。

Credit: NASA/JPL-Caltech/ESA/J. Hora (Harvard-Smithsonian CfA), C.R. O'Dell (Vanderbilt University)

A 2007 image of the Helix Nebula by Spitzer shows dust in the range 35 to 150 AU from the white dwarf. It is being described by the observers as comet debris.

An ultraviolet image of the Helix Nebula has been obtained by the GALEX instrument.

一张紫外图像显示了螺旋星云。

2007年斯皮策望远镜拍摄的螺旋星云图像显示，距离白矮星35到150个天文单位的尘埃。观测者称这些为彗星残骸。

Sources

Helix Nebula as Astronomy Picture of the Day
螺旋星云作为天文学图片中的每日图片
Spitzer image and description of Helix Nebula
斯皮瑟图像及螺旋星云描述
Comet debris in Helix Nebula?
螺旋星云中的彗星残骸？
R. Cowen, On the Trail of Dead Planets, Science News 171, 100, February 17, 2007.
R. Cowen, 《追踪死行星》, 《科学新闻》171卷第100期, 2007年2月17日。

源

NGC 7293：螺旋星云斯皮策望远镜拍摄的螺旋星云图片版权：NASA/JPL-Caltech/ESA/J. Hora (哈佛-史密松尼天体物理中心)，C.R. O'Dell (范德比尔特大学)

Index

Nebulae

索引星云

HyperPhysics********** Astrophysics

HyperPhysics ********** 天体物理学

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