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Neighborhood watch: Hubble spots a tiny amorphous galaxy in the local universe
The Hubble Space Telescope has been scouring the heavens from space for more than 30 years, making it one of the greatest success stories in astronomy.
Sure, the James Webb Space Telescope has been dominating the headlines lately. But ever since Hubble launched in 1990, the telescope has captured countless iconic images that have wowed millions, if not billions, of people. And it’s still going strong.
The latest notch in Hubble’s belt is the stunning image above, which captures a tiny, diffuse galaxy named UGCA 307. The galaxy is located some 26 million light-years from Earth in the constellation Corvus the Crow.
This diminutive galaxy displays an amorphous shape that’s nothing like the intricate spiral structure found in many larger galaxies, including our Milky Way and the nearby Andromeda Galaxy. Instead, UGCA 307 appears as little more than a small, fuzzy patch of stars.
Nonetheless, the new Hubble image does confirm that even this diffuse dwarf galaxy can form new stars. Within the hazy body of UGCA 307, Hubble picked up several enormous bubbles of hot gas (seen in red) that are bursting with star formation.
Dwarf galaxy UGCA 307 is thought to orbit the much larger and well-structured Sombrero Galaxy, much like the Large Magellanic Cloud orbits the Milky Way. In turn, UGCA 307 and the Sombrero make up a large cluster of galaxies on the southern edge of the even larger Virgo Supercluster. The Virgo Supercluster contains many thousands of galaxies, including our own Local Group, and some research suggests it is actually just one lobe of an even larger assemblage of galaxies known as the Laniakea Supercluster, which contains hundreds of thousands of galaxies.
Hubble captured the new image of UGCA 307 using its Advanced Camera for Surveys (ACS), which astronauts installed during Servicing Mission 3B in 2002. Unlike the James Webb Space Telescope, which operates nearly a million miles from Earth at a special spot called the second Lagrange point (L2), Hubble operates in low Earth orbit, roughly 330 miles (530 km) above Earth’s surface. This low orbit makes it possible for astronauts to visit, repair, and refurbish Hubble, which they did during five separate space shuttle missions carried out between 1993 and 2009.
The UGCA 307 image is not one of Hubble’s longer exposures, however. Instead, it’s akin to a snapshot. That’s because Hubble captured the image as part of an appropriately named survey program called The Every Known Nearby Galaxy Survey.
This program is an effort to get consistent Hubble data for as many of the Milky Way’s galactic neighbors as possible. Before the survey, Hubble had previously imaged some 75 percent of known galaxies within about 33 million light-years of Earth. The survey is intended to flesh out that sampling with roughly 150 snapshots of the remaining camera-shy galaxies.
Completion of The Every Known Nearby Galaxy Survey would not only provide a valuable archival record of nearly all nearby stars in the local universe. It would also reveal information on stellar demographics throughout a multitude of different galaxies, as well as provide astronomers with a more clear and complete picture of our cosmic neighborhood’s structure.
注释：
amorphous：adj
表示"无定形的"，means "having no definite form or distinct shape"，如：It is an amorphous colorless or white powder. 它是一种无定形的无色或白色粉末。
scour: v
1. 表示"搜寻"，means "search for"，如：The police scoured the area looking for the lost child. 警方搜遍这个地区寻找这个走失的孩子。
2. 表示" 擦洗"，means "rub hard or scrub"，如：This rusted pan does not scour easily.这只生锈的锅不容易擦干净。
notch: n
表示"等级；切口"，means "a V-shaped indentation"，如：I cut a notch in a stick. 我在一根棍子上刻了一个V字形。
Constellation: n
表示"星座；"，means "a configuration of stars as seen from the earth"，如：A constellation is a stellar system. 一个星座就是一个恒星星系。
Corvus: n
表示" 乌鸦座"，means "type genus of the Corvidae: crows and ravens"，如：A constellation in the Southern Hemisphere near Hydra and Corvus. 南天球的一个星座，位于长蛇座和乌鸦座附近。
diminutive: adj
表示"小的；"，means "very small;"，如：She has diminutive hands for an adult. 作为一个成年人,她的手显得非常小。
intricate: adj
表示" 复杂的"，means "having many complexly arranged elements; elaborate"，如：It was an intricate and ingenious system. 这是一个复杂而精致的体系。
Sombrero: n
表示"墨西哥阔边帽"，means "a straw hat with a tall crown and broad brim;"，如：When meeting ladies, he always raises his sombrero. 碰到女士，他总是举起他的墨西哥阔边帽以示敬意。
lobe: n
1. 表示"耳垂；"，means "(anatomy) a somewhat rounded subdivision of a bodily organ or part;"，如：Mike wants to get his lobe lanced. 迈克想在耳垂上穿个孔。
2. 表示"圆形突出部分"，means "(anatomy) a somewhat rounded subdivision of a bodily organ or part;"，如：Senator Kennedy's *(tumor) is the left *(parietal) lobe of brain.肯尼迪的肿瘤在大脑左边顶骨的圆形突出处。
assemblage: n
1.表示"装配；"，means "the social act of assembling"，如：his combination process is called the assemblage of stiffness matrices. 这种组合的过程称为刚度矩阵的装配。
2. 表示" 聚集"，means "a system of components assembled together for a particular purpose"，如：There is an odd assemblage of broken bits of furniture in this room. 这间屋子里放了一堆奇形怪状的破烂家具。
refurbish: v
表示" 刷新"，means "make brighter and prettier"，如：The flat will be refurbished for the new tenants. 这套房间将重新粉刷以接纳新房客。
akin: adj
表示"同族的；同类的"，means "related by blood;similar in quality or character"，如：He is near akin to us. 他和我们是近亲。
archival: adj
表示"档案的"，means "of or relating to archive"，如：Is Archival Work Too Cool and Hard? 档案工作太清苦?
multitude: n
表示" 大量；"，means " a large number"，如：A multitude of heroic figures emerge. 大量英雄人物出现了。
中文简要说明：
哈伯太空望远镜（Hubble Space Telescope）已经在太空中搜寻天空超过30年，虽然韦伯太空望远镜（James Webb Space Telescope）占尽了所有的风采，但是哈伯太空望远镜仍然是老当益壮，最近它带来了最新成就，发现了一个名为UGCA 307的不规则星系（amorphous galaxy）这个星系位于乌鸦座（Corvus the Crow）距离地球约2600万光年。
据「天文学期刊」（Astronomy Magazine）报导，这个小型不规则星系呈现出一个不定形的形状，与许多较大的星系例如我们的银河系（Milky Way），和我们邻居仙女座（Andromeda）所拥有的螺旋结构完全不同。
UGCA 307看起来只是一小块模糊的星星。尽管如此，哈伯的新图像确认了即使是这个微小的星系也能形成新的恒星，在UGCA 307模糊的身影中，哈伯拍摄到了数个充满恒星形成的热区。
就像大麦哲伦星系（Large Magellanic Cloud）环绕着我们的银河系一样。UGCA 307和「草帽星系」（Sombrero Galaxy）又组成了一个大型星系团，位于更大的处女座星系团（Virgo Supercluster）的南缘。
哈勃在低地球轨道上运行，距离地球表面约330英里(530公里)。这种低轨道使得航天员可以对其维修和升级，自1993年至2009年间进行了5次航天飞机任务。这次探寻UGCA 307是一个名为「已知邻近银河系调查」（Every Known Nearby Galaxy Survey）计划的一部分。在进UGCA 307的调查之前，哈伯太空望远镜已经在距离地球约3300万光年的范围内拍摄并建档了大约75％已知的星系。
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