死亡恒星的新视野
Eta Carinae是一个神秘的东东，特别是一颗纯粹被投出的明亮而不稳定的石头—按天文学说法—距离地球只有7500光年。这颗恒星被认为正在难以置信的速度消耗其核燃料，并且很快就会接近其爆炸的极限。当Eta Carinae真的爆炸时，将能在地球上看见一场引人注目的烟火，也许亮度能与月亮媲美。他的命运已经通过最近发现的SN2006gy被预知，SN2006gy是在一个星系附近的遗迹，同时也是至尽所发现的最明亮的恒星的爆炸。这颗恒星有移动的特性而且比SN2006gy爆炸的晚，所以由此可见Eta Carinae可能是在任何时间爆炸的（即不能确定）。
Eta Carinae，质量是太阳的100到150倍，这是一个不稳定平衡的临界点，也就是恒星的引力通常靠核反应堆所产生的强烈辐射制造的外层气压来平衡的。其意思也就是即使轻微的干扰，恒星都可能引起剧烈的表面物质抛射。在18世纪40年代，Eta Carinae层喷射了10倍于太阳质量的物质，由此在短时间内成为天空中第2亮的恒星。这次爆炸将很多其他恒星撕成碎片，但Eta Carinae却保留了下来。
最新的一张合成图展现了泰坦尼克事件的遗迹，相关数据是来自NASA的钱德拉X射线天文台和哈勃空间望远镜。蓝色部分表示寒冷的光发射，由哈勃探测到，来自摆脱恒星的尘埃和气体。这个琐屑形成了围绕恒星带有两极的壳，位于最明亮的光发射点附近。这个双极壳自己是被包裹了一层不整齐的微弱物质的云。一个不平常的喷发点从恒星到左上方。
钱德拉的数据，是用橘黄色和黄色来描述的，所展现的X射线是由脱离Eta Carinae进入附近区域的气体和尘埃物质所制造出来的，其过度的加热了气体至100万度。这个炽热的遮蔽物延伸到了远方的寒冷区，可见光波段的星云和表示外层相互作用的边缘。X射线的观测表明喷发的外层物质靠复杂的原子所浓缩，特别是氮，既在恒星的内部核反应堆反应又被撒到恒星的表面。钱德拉的观测结果同样也显示了在可见光波段以内的星云成长缓慢导致了X射线的反射。X射线的反射是通过靠恒星很近的可见光波段星云，这些X射线是由Eta Carinae表面高速流动气体（大约每小时100万英里）和其伴星的风碰撞所产生的。
其伴星在这些图片中并不是直接可见的，但在X射线波段是可见的，在靠近恒星的区域，表示了恒星的存在。天文学家不是确切的知道伴星在Eta Carinae的进化中是扮演怎样的一个角色，或者在其自己的未来中扮演什么角色。
Eta Carinae is a mysterious, extremely bright and unstable star located a mere stone's throw - astronomically speaking - from Earth at a distance of only about 7,500 light years.
The star is thought to be consuming its nuclear fuel at an incredible rate, while quickly drawing closer to its ultimate explosive demise. When Eta Carinae does explode, it will be a spectacular fireworks display seen from Earth, perhaps rivaling the moon in brilliance. Its fate has been foreshadowed by the recent discovery of SN2006gy, a supernova in a nearby galaxy that was the brightest stellar explosion ever seen. The erratic behavior of the star that later exploded as SN2006gy suggests that Eta Carinae may explode at any time.
Eta Carinae, a star between 100 and 150 more massive than the Sun, is near a point of unstable equilibrium where the star's gravity is almost balanced by the outward pressure of the intense radiation generated in the nuclear furnace. This means that slight perturbations of the star might cause enormous ejections of matter from its surface. In the 1840s, Eta Carinae had a massive eruption by ejecting more than 10 times the mass of the sun, to briefly become the second brightest star in the sky. This explosion would have torn most other stars to pieces but somehow Eta Carinae survived.
The latest composite image shows the remnants of that titanic event with new data from NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The blue regions show the cool optical emission, detected by Hubble, from the dust and gas thrown off the star. This debris forms a bipolar shell around the star, which lies near the brightest point of the optical emission. This bipolar shell is itself surrounded by a ragged cloud of fainter material. An unusual jet points from the star to the upper left.
Chandra's data, depicted in orange and yellow, shows the X-ray emission produced as material thrown off Eta Carinae rams into nearby gas and dust, heating gas to temperatures in excess of a million degrees. This hot shroud extends far beyond the cooler, optical nebula and represents the outer edge of the interaction region. The X-ray observations show that the ejected outer material is enriched by complex atoms, especially nitrogen, cooked inside the star's nuclear furnace and dredged up onto the stellar surface. The Chandra observations also show that the inner optical nebula glows faintly due to X-ray reflection. The X-rays reflected by the optical nebula come from very close to the star itself; these X-rays are generated by the high-speed collision of wind flowing from Eta Carinae's surface (moving at about 1 million miles per hour) with the wind of the companion star (which is about five times faster).
The companion is not directly visible in these images, but variability in X-rays in the regions close to the star signals the star's presence. Astronomers don't know exactly what role the companion has played in the evolution of Eta Carinae, or what role it will play in its future.
自翻
URL：http://spacespin.org/article.php/new-view-doomed-star
复合图
http://chandra.harvard.edu/photo/2007/etacar/etacar.jpg
可见光波段
蓝色
http://chandra.harvard.edu/photo/2007/etacar/etacar_opt.jpg
红色
http://chandra.harvard.edu/photo/2007/etacar/etacar_opt_red.jpg 这图美就美在中间的沙漏状遗迹和他的颜色。。给人一种高贵典雅的感觉
[ 本帖最后由 江涛 于 2008-2-29 22:10 编辑 ] 确实漂亮！::070821_09.jpg:: ::070821_01.jpg:: 江兄现在是牧夫新继任的每日一图啊！！！呵呵，以前是拉玛，现在是江兄！前段时间刚看到江兄还以为是我一个要好的朋友，跟你同姓同名啊::42:: 支持江兄！！ 几张图对比来看很不错！ 原帖由 白羊星座 于 2008-2-29 22:58 发表 http://www.astronomy.com.cn/bbs/images/common/back.gif
江兄现在是牧夫新继任的每日一图啊！！！呵呵，以前是拉玛，现在是江兄！前段时间刚看到江兄还以为是我一个要好的朋友，跟你同姓同名啊::42:: 支持江兄！！ ...
呵呵，多谢支持，MS现在拉玛为了避免撞车都不出手了，有点不好意思
回复 6# 的帖子
::42:: ::42:: 不要紧，江兄出手有中英文对照，比不上啊。 呵呵，拉玛谦虚了，偶那水平也就将就。。。对照也是为了大家一起有所进步，所以希望看帖的朋友能仔细的阅读一下，有错误也请指出[ 本帖最后由 江涛 于 2008-2-29 23:37 编辑 ] 好熟悉的图
似乎好多书都能见到 很漂亮，第一次见::070821_21.jpg:: 射线大气应该过得掉的，只是臭氧层不要再被破坏得厉害 翻译得不错，较精准
另外，在天之文的每日一图中，这幅图叫做“在劫难逃的海山二星” 美丽的准超新星::070821_04.jpg::
真希望它快点爆发::070821_04.jpg:: ::070821_02.jpg:: 超新星的美丽瞬间！::070821_04.jpg::
页:
[1]