另眼系列之螺旋星云（NGC7293）

图片转自:http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=ssc2006-01a

译文来源:http://www.bjp.org.cn/apod/2006-01/12/content_6081.htm


The Infrared Helix
The Helix Nebula, which is composed of gaseous shells and disks puffed out by a dying sunlike star, exhibits complex structure on the smallest visible scales. In this new image from NASA's Spitzer Space Telescope, infrared light at wavelengths of 3.2, 4.5, and 8.0 microns has been colored blue, green, and red (respectively). The color saturation also has been increased to intensify hues. The "cometary knots" show blue-green heads due to excitation of their molecular material from shocks or ultraviolet radiation. The tails of the cometary knots appear redder due to being shielded from the central star's ultraviolet radiation and wind by the heads of the knots.

红外波段的螺旋星云

版权：J. Hora (Harvard-Smithsonian CfA) et al., (SSC/Caltech), JPL-Caltech, NASA

    说明：在距离地球600多光年的宝瓶座内，有一颗类似太阳的垂死的恒星。在它最后几千年的生命里，形成了螺旋星云（NGC7293），一个离地球最近并被仔细研究的行星状星云范例，它也是典型的恒星演化的最后阶段。在这张斯皮策太空望远镜拍摄的螺旋星云的照片中，红外波段的辐射主要来自星云的氢分子云气。这些氢分子云气的分布不均，聚成了数以千计的彗星状纠结，每一个的大小大约是我们太阳系的两倍大。蓝色较高能量的辐射是来自头部，而尾部的辐射则偏红，这显示尾部受到了遮掩，没有受到中心星恒星风及强烈紫外辐射的照射。螺旋星云的大小约为2.5光年。再过五十亿年，太阳预期也会进入行星状星云阶段。（翻译：陈昌）

                               
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[ 本帖最后由 寻找拉玛 于 2008-8-19 14:19 编辑 ]

转自:http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=ssc2006-01b


The Mark of a Dying StarSix hundred and fifty light-years away in the constellation Aquarius, a dead star about the size of Earth, is refusing to fade away peacefully. In death, it is spewing out massive amounts of hot gas and intense ultraviolet radiation, creating a spectacular object called a "planetary nebula."

In this false-color image, NASA's Hubble and Spitzer Space Telescopes have teamed up to capture the complex structure of the object, called the Helix nebula, in unprecedented detail. The composite picture is made up of visible data from Hubble and infrared data from Spitzer.

The dead star, called a white dwarf, can be seen at the center of the image as a white dot. All of the colorful gaseous material seen in the image was once part of the central star, but was lost in the death throes of the star on its way to becoming a white dwarf. The intense ultraviolet radiation being released by the white dwarf is heating and destabilizing the molecules in its surrounding environment, starting from the inside out.

Like an electric stovetop slowly heating up from the center first, the hottest and most unstable gas molecules can be seen at the center of the nebula as wisps of blue. The transition to more stable and cooler molecules is clearly depicted as the color of the gas changes from very hot (blue) to hot (yellow) and warm (red).

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 Spitzer observations at 4.5 and 8.0 microns.

                               
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[ 本帖最后由 寻找拉玛 于 2008-8-19 14:36 编辑 ]

图片转自:http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=ssc2007-03a


译文来源:http://www.phys.ncku.edu.tw/~astrolab/mirrors/apod/ap070223.html

Comets Kick up Dust in Helix NebulaThis infrared image from NASA's Spitzer Space Telescope shows the Helix nebula, a cosmic starlet often photographed by amateur astronomers for its vivid colors and eerie resemblance to a giant eye.

The nebula, located about 700 light-years away in the constellation Aquarius, belongs to a class of objects called planetary nebulae. Discovered in the 18th century, these colorful beauties were named for their resemblance to gas-giant planets like Jupiter.

Planetary nebulae are the remains of stars that once looked a lot like our sun. When sun-like stars die, they puff out their outer gaseous layers. These layers are heated by the hot core of the dead star, called a white dwarf, and shine with infrared and visible colors. Our own sun will blossom into a planetary nebula when it dies in about five billion years.

In Spitzer's infrared view of the Helix nebula, the eye looks more like that of a green monster's. Infrared light from the outer gaseous layers is represented in blues and greens. The white dwarf is visible as a tiny white dot in the center of the picture. The red color in the middle of the eye denotes the final layers of gas blown out when the star died.

The brighter red circle in the very center is the glow of a dusty disk circling the white dwarf (the disk itself is too small to be resolved). This dust, discovered by Spitzer's infrared heat-seeking vision, was most likely kicked up by comets that survived the death of their star. Before the star died, its comets and possibly planets would have orbited the star in an orderly fashion. But when the star blew off its outer layers, the icy bodies and outer planets would have been tossed about and into each other, resulting in an ongoing cosmic dust storm. Any inner planets in the system would have burned up or been swallowed as their dying star expanded.

So far, the Helix nebula is one of only a few dead-star systems in which evidence for comet survivors has been found.

This image is made up of data from Spitzer's infrared array camera and multiband imaging photometer. Blue shows infrared light of 3.6 to 4.5 microns; green shows infrared light of 5.8 to 8 microns; and red shows infrared light of 24 microns.



螺旋星云(Helix nebula)以及星尘

        说明:这是史匹哲太空望远镜以红外波段拍摄的螺旋星云影像，中心亮点为星云核心，是一颗白矮星，周围为星云的星尘，星尘使得像是瞳孔的宇宙之眼更加火红。这张史匹哲太空望远镜的诡异影像显示螺旋星云(Helix Nebula) NGC 7293的中心辐射出红外线。环绕中心白矮星的星尘与气体大约有2个光年的半径，是一个绝佳的行星状星云的例子，代表像太阳这样的恒星演化的最后阶段。但是史匹哲所记录的资料也显示星云中心白矮星位在特别强的红外线内，这是过去没有发现的现象。模型暗示可能是由星尘碎片所组成尘埃盘。虽然星云的物质在几千年前被抛射出去，星球附近的尘埃可能是附近的尘埃盘的碰撞所导致，有点类似于太阳系统的科伊伯带(Kuiper Belt)或是奥特云（Oort cloud ） 。这些像是彗星一般的物体虽然形成在外头的行星系统，却仍然能够在星球演化的后期存活。

                               
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[ 本帖最后由 寻找拉玛 于 2008-8-19 14:07 编辑 ]

http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=sig07-016


The Infrared Helix (Expanded View)

The Helix Nebula, which is composed of gaseous shells and disks puffed out by a dying sunlike star, exhibits complex structure on the smallest visible scales. In this new image from NASA's Spitzer Space Telescope, infrared light at wavelengths of 3.2, 4.5, and 8.0 microns has been colored blue, green, and red (respectively). The "cometary knots" show blue-green heads due to excitation of their molecular material from shocks or ultraviolet radiation. The tails of the cometary knots appear redder due to being shielded from the central star's ultraviolet radiation and wind by the heads of the knots.

                               
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http://ipac.jpl.nasa.gov/media_images/sig07-016.jpg


[ 本帖最后由 寻找拉玛 于 2008-8-19 14:56 编辑 ]

好啊！！今天的图版好热闹！！！很多漂亮的图片啊！！开心！！

老图新照。。。。爽。。。

难道有人发过了?

很美啊，不过这些图我见过。