天文每日一图2005.4.2-4.5

天鹅座X-1:黑暗中形成的黑洞？
黑洞形成于大质量恒星核的塌缩，一般认为会有壮观的超新星爆发作为前导。这种极端高能的塌缩过程也被认为是神秘的宇宙伽马射线暴的可能解释之一。但是研究人员最近提出，银河系最著名的黑洞天鹅座X-1诞生于大质量恒星塌缩，但并没有超新星爆发。他们的动力学证据可以概括于这张天鹅座天区的绚丽的彩色照片之中。照片展示了天鹅座X-1和一个已知的大质量星团天鹅座OB3（黄圈）。箭头表示天鹅座X-1的速度大小和方向与天鹅座OB3中大质量恒星的平均速度大小和方向的比较。相似的运动表明天鹅座X-1的前身是这个星团的成员，它的运动轨迹并没有因为成为黑洞而改变。相反，如果天鹅座X-1诞生于激烈的超新星爆发，那它会由于受到猛烈的反冲而改变运动方向。如果不是诞生于超新星爆发，那天鹅座X-1黑洞会不会形成于银河系内的一次暗弱的伽马射线暴？（小海译注，小兔校）

Cyg X-1: Can Black Holes Form in the Dark?
Credit: I. F. Mirabel and I. Rodrigues (IAFE, SAp/CEA)
Explanation: The formation of a black hole from the collapsing core of a massive star is thought to be heralded by a spectacular supernova explosion. Such an extremely energetic collapse is also a leading explanation for the mysterious cosmic gamma-ray bursts. But researchers now suggest that the Milky Way's most famous black hole, Cygnus X-1, was born when a massive star collapsed -- without any supernova explosion at all. Their dynamical evidence is summarized in this color image of a gorgeous region in Cygnus, showing Cyg X-1 and a cluster of massive stars (yellow circles) known as Cygnus OB3. Arrows compare the measured direction and speed of Cyg X-1 and the average direction and speed of the massive stars of Cyg OB3. The similar motions indicate that Cyg X-1's progenitor star was itself a cluster member and that its path was not altered at all when it became a black hole. In contrast, if Cyg X-1 were born in a violent supernova it would have likely received a fierce kick, changing its course. If not a supernova, could the formation of the Cyg X-1 black hole have produced a dark gamma-ray burst in the Milky Way?
注：图上纵轴Galactic latitude为银纬，横轴Galactic longitude为银经，单位均为度

小兔冒出来~~~^0^大家好，初次发帖，HEHE

银河系中心的射电弧
是什么导致了我们银河系中心的这种不寻常的结构呢？斜穿过这幅射电图像上方的的长平行线合称为银河系中心的射电弧，这些弧刚好从银盘穿出。把射电弧和银河系中心联系起来的是一些奇怪的弯曲细丝，这些细丝被我们称为拱形物。在底部的明亮射电结构很可能包围着银河系中心的黑洞（也就是我们叫做人马座A*的位置）一种射电弧起源的假设认为射电弧和拱形物形成这种结构是因为炽热的等离子体沿着稳定的磁力线流动。最近钱德拉塞卡X射线天文台拍摄的图象显示这个些离子体正和附近的冷气体云发生碰撞。（小兔译）

The Galactic Center Radio Arc
Credit: Farhad Yusef-Zadeh et al. (Northwestern), VLA, NRAO
Explanation: What causes this unusual structure near the center of our Galaxy? The long parallel rays slanting across the top of the above radio image are known collectively as the Galactic Center Radio Arc and jut straight out from the Galactic plane. The Radio Arc is connected to the Galactic center by strange curving filaments known as the Arches. The bright radio structure at the bottom right likely surrounds a black hole at the Galactic center and is known as Sagittarius A*. One origin hypothesis holds that the Radio Arc and the Arches have their geometry because they contain hot plasma flowing along lines of constant magnetic field. Recent images from the Chandra X-ray Observatory appear to show this plasma colliding with a nearby cloud of cold gas.

NGC 1316: 星系碰撞之后
这个形状奇怪的星系是如何形成的呢？天文学家们化身为侦探，试图找出NGC1316中恒星，气体和尘埃这种不寻常的混乱的起源。初步的鉴定表明，NGC1316是一个巨大的椭圆星系，但却包含着通常在旋涡星系里出现的暗色尘带。上面这张哈勃望远镜拍摄的精细图像将有助于我们重构这种混乱形成的历史。更仔细的调查发现只有少量的低质量球状星团在NGC1316的中心。这意味着这个星系在过去的几十亿年中曾经和其他星系有过碰撞或并合。在那样的碰撞之后，大量的球状星团将在致密的星系中心被摧毁。暗色的斑点和尘带表示有一个或者更多的被吞噬的星系原来是旋涡星系。NGC1316有60，000光年宽，坐落在天炉座星系中，距离我们7千5百万光年远。（小兔译）
NGC 1316: After Galaxies Collide
Credit: P. Goudfrooij (STScI), Hubble Heritage Team, (STScI/AURA), ESA, NASA
Explanation: How did this strange-looking galaxy form? Astronomers turn detectives when trying to figure out the cause of unusual jumbles of stars, gas, and dust like NGC 1316. A preliminary inspection indicates that NGC 1316 is an enormous elliptical galaxy that includes dark dust lanes usually found in a spiral. The above image taken by the Hubble Space Telescope shows details, however, that help in reconstructing the history of this gigantic jumble. Close inspection finds fewer low mass globular clusters of stars toward NGC 1316's center. Such an effect is expected in galaxies that have undergone collisions or merging with other galaxies in the past few billion years. After such collisions, many star clusters would be destroyed in the dense galactic center. The dark knots and lanes of dust indicate that one or more of the devoured galaxies were spiral galaxies. NGC 1316 spans about 60,000 light years and lies about 75 million light years away toward the constellation of the Furnace.

来自一颗遥远恒星的光
我们第一次发现了远离太阳系的行星所发出的光。这颗恒星，如上图所绘，它的光度是通过对比它掩藏在恒星之后只能看到恒星的光时和两者的光都可见时的差异得到的。运行在地球轨道上的斯必泽太空望远镜（Spitzer Space Telescope）对它在红外波段进行了观测，因为在这个波段行星本身发出的光比它反射恒星的光要强得多。直接探测到光线使我们可以测量这颗行星（HD209458b）的温度和大小，事实表明，行星HD209458b的质量比我们预想的要大，而且它围绕恒星以一个出人意料的近乎正圆的公转轨道运动。（小兔译）

图太大了,处理了一下，点这里看原图http://antwrp.gsfc.nasa.gov/apod ... pse_spitzer_big.jpg

Light From A Distant Planet
Illustration Credit: R. Hurt (SSC-Caltech), JPL-Caltech, NASA
Explanation: Light emitted by a planet far beyond our Solar System has been identified for the first time. The planet, illustrated in the above drawing, had its light detected by comparing the brightness of only the parent star, when the planet was behind the star, to the light emitted when both the planet and its parent star were visible. The Earth-orbiting Spitzer Space Telescope made the observation in infrared light, where the intrinsic glow of the planet outshines the light it reflects from its central star. The direct observation of light allowed a measurement of both the temperature and size of the planet: HD 209458b. Planet HD 209458b was confirmed to be larger than expected for its mass and on an orbit around its parent star that was unexpectedly close to a circle.

好啊！好啊！ :shock:

第3幅图没看明白。。是模拟的还是想象的啊

看不懂啊

是啊，你就不应该挖坟