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2021年09月08日:仙女大星系方向的深空影像-(The Deep Sky Toward Andromeda)
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2001-04-10
2001年04月10日:涡状星系 M51 的尘埃带和恆星-(M51: The Whirlpool Galaxy in Dust and Stars)
2001年04月10日:涡状星系 M51 的尘埃带和恆星-(M51: The Whirlpool Galaxy in Dust and Stars)--原图下载{mtitle title="涡状星系 M51 的尘埃带和恆星"/}Credit: N. Scoville (Caltech), T. Rector ((NOAO) et al., Hubble Heritage Team, NASA说明: 距离我们三千万光年的涡状星系M51,又称为是NGC 5194,它是一个很典型的螺旋星系,也是夜空中最明亮且最上镜头的星系之一。虽然上面这张影像所展示的是太红所以通常在地面看不到的M51结构,它是由哈伯望远镜及美国基特峰 (KPNO)国家天文台90公分口径的望远镜所拍摄的影像组合而成的。不过任何拥有一具双筒望远镜的观星人,都应该能在北天的猎犬座 (Canes Venaciti)看到这个涡状的美丽星系。M51 被归类成Sc 型的螺旋星系,它也是M51所在星系团最突出的星系。天文学家怀疑M51的螺旋结构,是因为它和位在影像顶端外的小型星系重力作用下的产物。{lamp/}原文:{mtitle title="M51: The Whirlpool Galaxy in Dust and Stars"/}Credit: N. Scoville (Caltech), T. Rector ((NOAO) et al., Hubble Heritage Team, NASAExplanation: The Whirlpool Galaxy is a classic spiral galaxy. At only 30 million light years distant and fully 60thousand light years across, M51, also known as NGC 5194, is one of the brightest and most picturesque galaxies on the sky. The above image is a digital combination of a ground-based image from the 0.9-meter telescope at Kitt Peak National Observatory and a space-based image from the Hubble Space Telescope highlighting sharp features normally too red to be seen.Anyone with a good pair of binoculars, however, can see this Whirlpool toward the constellation of Canes Venatici. M51 is a spiral galaxy of type Sc and is the dominant member of a whole group of galaxies. Astronomers speculate that M51's spiral structure isprimarily due to its gravitational interaction with a smaller galaxy just off the top of this image.
2001年04月10日
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2000-12-15
2000年12月15日:IC443的中子星-(IC443's Neutron Star)
2000年12月15日:IC443的中子星-(IC443's Neutron Star)--原图下载{mtitle title="IC443的中子星"/}Credit: C. Olbert,C. Clearfield,N. Williams,J. Keohane(NCSSM),NASA说明: 中子星是现代天文物理中最奇特天体之一,而从钱卓拉观测站 (Chandra)的X射线数据和极大阵列的无线电波数据,一个研究群最近在超新星遗骸IC 443之内,发现了一颗可能是中子星的天体。在上面这张假色X射线影像中,它是位在右下夕的红色光源。这颗位在双子座 (Gemini)的中子星,是由大质量恒星核心塌缩而成的超緻密天体,它的直径大约有20公里,不过有比太阳还要大的质量!很幸运的是,这颗在很久以前爆炸的恒星,距离我们有5000光年,对地球的生物来说算是非常安全的距离了。到底是多久以前发生的事呢?根据这颗中子星在云气内所产生的弓形波之形状,研究人员可以估算出它冲离爆炸中心的速度。然后,从它的移动的速度和行经的距离,美国北卡罗来纳州科学与数学高中的三位学生和一位教师所组成的研究团队,估算出三万年前的地球人应看过这次超新星爆炸。{lamp/}原文:{mtitle title="IC443's Neutron Star"/}Credit: C. Olbert,C. Clearfield,N. Williams,J. Keohane(NCSSM),NASAExplanation: Usingx-ray data from the orbitingChandra Observatoryalong with radio data from theVery Large Array,a team of researchers hasdiscovered evidence fora new example of one of the most bizarre objects known tomodern astrophysics -- aneutron star.Embedded withinsupernova remnant IC443,the suspected neutron starappears as the reddish source at the lower rightin this false-color x-ray image.Perhaps 20 kilometers across but with more mass than the Sun,this ultracompact object is the collapsed core of a massivestar.The core collapsed when the star, located a reassuring5,000 light-years awayin the constellationGemini, exploded long ago.How long ago?Judging from the characteristicbow wave shape of thex-ray nebulathe researchers have estimated the speed of the neutronstar as it plows away from the explosion site.Comparing the speed to the measured distance traveled fromthe center of IC443,the team,three high school students and a teacher from theNorth Carolina School for Science and Mathematics,calculated that the light from the supernovaexplosion arrived at Earth about 30,000 years ago.
2000年12月15日
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2000-04-19
2000年04月19日:创下120亿光年距离新记录的类星体 (quasar)-(Redshift 5.8: A New Farthest Quasar)
2000年04月19日:创下120亿光年距离新记录的类星体 (quasar)-(Redshift 5.8: A New Farthest Quasar)--原图下载{mtitle title="创下120亿光年距离新记录的类星体 (quasar)"/}Credit: Stephen Kent (FNAL), SDSS Collaboration说明: 类星体 (quasar)距离的记录又被打破了,现在宇宙中没有任何天体的距离,比上图箭头所指的类星体还要远。天文学家是靠量测类天体光谱的红位移量,来推断它们的距离,虽然在目前红位移量 (redshift)和距离之间的关係,还是有些不确定性,不过红位移量愈高,代表天体的距离愈远。而这个最近发现的类星体,它的红位移量高达5.82,相当于它的距离可能有120亿光年远。也就是说,我们现在所看到的光,可能是在宇宙年龄少于10亿年时所发出的,当时宇宙的年龄不到现在的十分之一。和其他的类星体很相似,这个类星体可能是一个核心有颗大黑洞的遥远星系。不过,先不急着合上你的记录登记簿,因为史隆巡天计画 (SDSS) 所发现的其他类星体之距离,正在被分析和确认之中,而有些类星体的红位移量可能会超过6,换算成距离可能会超过125亿光年。{lamp/}原文:{mtitle title="Redshift 5.8: A New Farthest Quasar"/}Credit: Stephen Kent (FNAL), SDSS CollaborationExplanation: The distance record for a quasarhas been broken yet again. At the present time, no other object in the universe has been found to be more distant than the above speck. The recently discovered quasar has been clocked at redshift 5.82. The exact relation between redshift and distance remains presently unknown, although surely higher redshifts do mean greater distance. The above quasar is likely billions of light-years away and so is seen when the universe was younger than one billion years old, less than a tenth of its present age. Like all quasars, this object is probably a large black hole in the center of a distant galaxy.Don't close the record book yet, though. The redshifts to several other SDSS-discovered quasars are currently being measured, some of which might have redshifts greater than six.
2000年04月19日
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