NASA哈勃太空望远镜观测巨型星系

NASA哈勃太空望远镜观测巨型星系

ByNASA中文

这个巨型螺旋星系或许会被称为“哥斯拉星系”（Godzilla galaxy），因为该星系有可能是其所在宇宙中已知的最大星系。该星系名为UGC 2885，比银河系宽2.5倍，其恒星数量则是银河系的10倍。 不过研究人员表示，UGC 2885星系是一个“温和的巨人”，因为它看上去没有与其他大型星系碰撞而过着相对静态的生活。在过去数十亿年间，它逐渐从星系间的丝状结构中吸收积累了氢，以缓慢而稳定的速度制造新恒星，其恒星诞生速率约为银河系的一半。事实上，该星系的超大质量中心黑洞也是一个沉睡的巨人。因为该星系似乎并不吞噬比它小得多的卫星星系，从而缺乏流入的气体。 肯塔基州路易斯维尔大学的本尼•霍尔维达（Benne Holwerda）用美国国家航空航天局（NASA）的哈勃太空望远镜对UGC 2885星系进行了观测，并以天文学家维拉•鲁宾（Vera Rubin，1928 – 2016）的名字给该星系起了个绰号，叫做“鲁宾星系”（Rubin’s galaxy）。 这张由哈勃太空望远镜拍摄的照片展示了巨型螺旋状星系UGC 2885，它位于距离地球2.32亿光年远的英仙座北部。该星系比银河系宽2.5倍，其恒星数量是银河系的10倍。在这幅图像中，我们可以看到银河系中的许多前景恒星，这些恒星可以通过它们的衍射峰来被识别。最亮的恒星在银河系的圆盘“乱入镜头”（photobomb）。该星系的昵称叫做“鲁宾星系”，以天文学家维拉•鲁宾（Vera Rubin ，1928-2016）的名字命名。 版权：NASA、欧洲航天局（ESA）和B. Holwerda（路易斯维尔大学） 霍尔维达表示：“我的研究在很大程度上受到了维拉•鲁宾在1980年关于UGC 2885星系大小的研究的启发”。维拉•鲁宾测量了该星系的旋转，并且由此发现了暗物质存在的证据，暗物质占据了该星系的大部分质量。“我们认为这是一个具有纪念意义的事情。在我们的观测中引用鲁宾博士的研究，这是我们最初的哈勃计划中的重要组成部分。” 霍尔维达于2020年1月6日在美国夏威夷檀香山举行的第235届美国天文学会年会上展示了其研究成果，试图解释了究竟是什么原因导致了UGC 2885星系的巨大规模。他表示：“我们目前还不太清楚该星系是如何变得这么庞大的。它的大小足以使其形成一个圆盘星系，而又不会触及任何其他空间。” 我们所知的一条线索是，UGC 2885星系在空间上是非常孤立的，并且附近没有任何星系可以撞击并破坏其圆盘形状。 随着时间的推移，UGC 2885星系是否吞噬了更小的卫星星系？抑或只是缓慢地为新恒星积累了气体？霍尔维达表示：“该星系似乎一直在缓慢生长。”利用哈勃太空望远镜的超高分辨率，霍尔维达的团队正在计算银河系光晕中的球状星团数量。大量星系团将会提供证据，证明它们是在数十亿年时间从被吞噬的较小星系中被捕获的。 NASA即将发射的詹姆斯•韦伯太空望远镜（James Webb Space Telescope）可以用来探测该星系的中心以及球状星团的数量。NASA计划中的广域红外探测望远镜（Wide Field Infrared Survey Telescope，WFIRST）将对其星系群，尤其是整个光环群进行更全面的普查。霍尔维达表示：“这两架太空望远镜的红外线捕捉能力将使我们更清楚地看到底层的恒星群。”这对哈勃太空望远镜可见光捕捉能力进行了补充，以追踪整个星系中稀疏的恒星形成。 在这幅图像中，我们可以看到银河系中的许多前景恒星，这些恒星可以通过其衍射峰来被识别。尽管UGC 2885星系实际上位于我们2.32亿光年之外的英仙座北部，其最明亮的部分看上去似乎位于星系盘的顶部。 来源： https://www.nasa.gov/feature/goddard/2020/nasas-hubble-surveys-gigantic-galaxy

南冕座的恒星和尘埃

南冕座的恒星和尘埃

ByNASA中文

2020 January 12 Stars and Dust in Corona Australis Image Credit & Copyright: CHART32 Team, Processing – Johannes Schedler Explanation: Cosmic dust clouds and young, energetic stars inhabit this telescopic vista, less than 500 light-years away toward the northern boundary of Corona Australis, the Southern Crown. The dust clouds effectively block light from more distant background stars in the Milky Way. But the striking complex of reflection nebulae cataloged as NGC 6726, 6727, and IC 4812 produce a characteristic blue color as light from the region’s young hot stars is reflected by the cosmic dust. The dust also obscures from view stars still in the process of formation. At the left, smaller yellowish nebula NGC 6729 bends around young variable star R Coronae Australis. Just…

雪花星团

雪花星团

ByGotthew

Newborn stars, hidden behind thick dust, are revealed in this image of a section of the so-called Christmas Tree Cluster from NASA’s Spitzer Space Telescope. The newly revealed infant stars appear as pink and red specks toward the center and appear to have formed in regularly spaced intervals along linear structures in a configuration that resembles the spokes of a wheel or the pattern of a snowflake. Hence, astronomers have nicknamed this the “Snowflake Cluster.” Star-forming clouds like this one are dynamic and evolving structures. Since the stars trace the straight line pattern of spokes of a wheel, scientists believe that these are newborn stars, or “protostars.” At a mere 100,000 years old, these infant structures have yet to “crawl” away from their location of…

北方冬季天空的全景影像

北方冬季天空的全景影像

ByNASA中文

2019 December 24 A Northern Winter Sky Panorama Image Credit & Copyright: Tomas Slovinsky Explanation: What stars shine in Earth’s northern hemisphere during winter? The featured image highlights a number of bright stars visible earlier this month. The image is a 360-degree horizontal-composite panorama of 66 vertical frames taken consecutively with the same camera and from the same location at about 2:30 am. Famous stars visible in the picture include Castor & Pollux toward the southeast on the left, Sirius just over the horizon toward the south, Capella just over the arch of the Milky Way Galaxy toward the west, and Polaris toward the north on the right. Captured by coincidence is a meteor on the far left. In the foreground is the Museum of…

哈勃太空望远镜观测到一个发光的星系

哈勃太空望远镜观测到一个发光的星系

ByNASA中文

For this image, the NASA/ESA Hubble Space Telescope turned its powerful eye toward an emission-line galaxy called NGC 3749. When astronomers explore the contents and constituent parts of a galaxy somewhere in the universe, they use various techniques and tools. One of these is to spread out the incoming light from that galaxy into a spectrum and explore its properties. This is done in much the same way as a glass prism spreads white light into its constituent wavelengths to create a rainbow. By hunting for specific signs of emission from various elements within a galaxy’s spectrum of light —so-called emission lines — or, conversely, the signs of absorption from other elements — so-called absorption lines — astronomers can start to deduce what might be…

哈勃太空望远镜发现了一个奇怪的螺旋

哈勃太空望远镜发现了一个奇怪的螺旋

ByNASA中文

The universe is simply so vast that it can be difficult to maintain a sense of scale. Many galaxies we see through telescopes such as the NASA/ESA Hubble Space Telescope, the source of this beautiful image, look relatively similar: spiraling arms, a glowing center, and a mixture of bright specks of star formation and dark ripples of cosmic dust weaving throughout. This galaxy, a spiral galaxy named NGC 772, is no exception. It actually has much in common with our home galaxy, the Milky Way. Each boasts a few satellite galaxies, small galaxies that closely orbit and are gravitationally bound to their parent galaxies. One of NGC 772’s spiral arms has been distorted and disrupted by one of these satellites (NGC 770 — not visible…

恒星珠宝盒：疏散星团NGC 290

恒星珠宝盒：疏散星团NGC 290

ByNASA中文

2019 October 13 A Stellar Jewel Box: Open Cluster NGC 290 Image Credit: NASA, ESA, Hubble; Acknowledgement: E. Olzewski (U. Arizona) Explanation: Jewels don’t shine this bright — only stars do. Like gems in a jewel box, though, the stars of open cluster NGC 290 glitter in a beautiful display of brightness and color. The photogenic cluster, pictured here, was captured in 2006 by the orbiting Hubble Space Telescope. Open clusters of stars are younger, contain few stars, and contain a much higher fraction of blue stars than do globular clusters of stars. NGC 290 lies about 200,000 light-years distant in a neighboring galaxy called the Small Cloud of Magellan (SMC). The open cluster contains hundreds of stars and spans about 65 light years across….

一起宇宙惨案

一起宇宙惨案

ByNASA中文

Credit:NASA NASA的凌星系外行星巡天望远镜(TESS)首次观测到一起宇宙惨案，一颗黑洞撕裂了一颗恒星，称为潮汐瓦解事件（TDE），这起事件名为ASASSN-19bt。 NASA的尼尔·盖恩斯·斯威夫特天文台和其他设施将对此进行了后续观测，这是对恒星毁灭事件早期时刻迄今进行的最详细观察，研究论文发表在2019年9月27日的天体物理学杂志。 论文合作者Patrick Vallely称：“早期的TESS数据让我们能够看到离黑洞非常近的光，比我们之前看到的要近得多。”ASASSN-19bt的亮度上升非常平稳，这也有助于我们确定这是一起潮汐瓦解事件，而不是其他类型的爆发。 全天自动测量超新星（All Sky Automated Survey for SuperNovae，简写ASAS-SN）于1月29日发现了这一事件，ASAS-SN是一个由20个望远镜组成的全球网络，总部位于俄亥俄州立大学（OSU）。由于TESS当时观测到的是同一区域，且在1月21日首次观测到这一事件，但TESS每两周向地球传回一次数据，接收到的数据还需要在NASA艾姆斯研究中心进行处理，所以直到3月13日，TESS才有第一批潮汐瓦解事件的数据。 Credit: NASA’s Goddard Space Flight Center 天文学学家们认为产生ASASSN-19bt事件的黑洞质量，大约是太阳质量的600万倍，这个黑洞坐落于星系2MASX J07001137-6602251的中心，位于飞鱼座方向，距离我们大约3.77亿光年，被摧毁的恒星质量与我们太阳相当。 潮汐瓦解事件极为罕见，在银河系大小的星系中，大约每1万至10万年间发生一次，相比之下超新星每100年左右发生一次，截止目前，天文学家总共观测到大约40次潮汐瓦解事件。 参见 [1]https://www.nasa.gov/feature/goddard/2019/nasa-s-tess-mission-spots-its-1st-star-shredding-black-hole [2]https://svs.gsfc.nasa.gov/13237

哈勃太空望远镜拍摄到了动态垂死的恒星

哈勃太空望远镜拍摄到了动态垂死的恒星

ByNASA中文

This atmospheric image taken with the NASA/ESA Hubble Space Telescope shows a dark, gloomy scene in the constellation of Gemini (the Twins). The subject of this image confused astronomers when it was first studied — rather than being classified as a single object, it was instead recorded as two objects, owing to its symmetrical lobed structure (known as NGC 2371 and NGC 2372, though sometimes referred to together as NGC 2371/2). These two lobes are visible to the lower left and upper right of the frame, and together form something known as a planetary nebula. Despite the name, such nebulas have nothing to do with planets; NGC 2371/2 formed when a Sun-like star reached the end of its life and blasted off its outer layers,…

哈勃太空望远镜拍摄的恒星气体发光的照片

哈勃太空望远镜拍摄的恒星气体发光的照片

ByNASA中文

Although it looks more like an entity seen through a microscope than a telescope, this rounded object, named NGC 2022, is certainly not algae or tiny, blobby jellyfish. Instead, it is a vast orb of gas in space, cast off by an aging star. The star is visible in the orb’s center, shining through the gases it formerly held onto for most of its stellar life. When stars like the Sun grow advanced in age, they expand and glow red. These so-called red giants then begin to lose their outer layers of material into space. More than half of such a star’s mass can be shed in this manner, forming a shell of surrounding gas. At the same time, the star’s core shrinks and grows…