回力棒星云是宇宙中已知的最寒冷之地。天文学家们运用设在智利的一台射电望远镜对它展开了新观测，以便更多地了解其寒冷的性状，并确定其怪异的鬼怪模样下的真实形状。

回力棒星云（Boomerangnebula）在宇宙中寒意袭人，其温度为开氏1度（摄氏零下272度），是宇宙中已知的最寒冷之地——比形成宇宙的“大爆炸”（BigBang）后微弱的余辉还要寒冷。

天文学家们运用位于智利的“阿塔卡玛大型毫米及次毫米波阵列”（Atacama LargeMillimeter/submillimeter Array,ALMA）望远镜对回力棒星云展开了新观测，以便更多地了解其寒冷的性状，并确定它怪异的鬼怪模样下的真实形状。

位于加利福尼亚州帕萨迪纳（Pasadena, California）的美国国家航空航天局（NASA）喷气推进实验室（JetPropulsion Laboratory）的研究员及首席科学家拉夫温德拉•萨哈伊（RaghvendraSahai）是发表在《天体物理学刊》（AstrophysicalJournal）上的一篇文章的主要执笔人，他说：“这个超寒冷的物体非常有意思，通过‘阿塔卡玛大型毫米及次毫米波阵列’望远镜，我们正在越来越多地了解其真实本质。从地球上的光学望远镜看到的好像是一个双波瓣或回力棒的形状，实际上是一个正快速扩展到太空中的宽广得多的结构。”

上图为该星云透过“阿塔卡玛大型毫米及次毫米波阵列”望远镜展示的真实形状。背景中通过NASA的哈勃太空望远镜（HubbleSpaceTelescope）在可见光下观察到的蓝色结构呈典型的具有狭窄中心区域的双波瓣形状。“阿塔卡玛大型毫米及次毫米波阵列”望远镜的分辨率及观测低温气体分子的能力揭示出该星云拉长的形状，在图中呈红色。

该篇文章的其他作者包括来自瑞典昂萨拉（Onsala）的查尔姆斯理工大学（Chalmers University ofTechnology）的沃特•维勒明斯（Wouter Vlemmings），来自纽约的纽约大学（New YorkUniversity）的帕特里克•哈金斯（Patrick Huggins），来自智利圣地亚哥（Santiago deChile）的“阿塔卡玛大型毫米及次毫米波阵列”联合天文台（Joint ALMAObservatory）的拉尔斯埃克•尼曼（Lars-AkeNyman），来自联邦科学与工业研究组织（CSIRO）的澳大利亚国家望远镜中心（Australia TelescopeNational Facility）的亚尼斯•贡尼达奇斯（Yiannis Gonidakis）。

国际天文学设施“阿塔卡玛大型毫米及次毫米波阵列”是欧洲、北美和东亚与智利共和国合作开办的一个伙伴项目。该设施的建设和运行由代表欧洲的欧洲南半球天文台（EuropeanSouthern Observatory）、代表北美的美国国家射电天文台（National Radio AstronomyObservatory）和代表东亚的日本国立天文台（National Astronomical Observatory ofJapan）负责。

Ghostly Specter Haunts “Coldest Place in the Universe”

The Boomerang nebula is the coldest known object in theuniverse. Astronomers using a radio telescope in Chile have taken anew look at it to learn more about its frigid properties and todetermine its true shape, which has an eerily ghost-likeappearance.

At a cosmologically crisp 1 degree Kelvin (minus 272 degreesCelsius), the Boomerang nebula is the coldest known object in theuniverse — colder than the faint afterglow of the Big Bang, theexplosive event that created the cosmos.

Astronomers using the Atacama Large Millimeter/submillimeterArray (ALMA) telescope in Chile have taken a new look at thisobject to learn more about its frigid properties and to determineits true shape, which has an eerily ghost-like appearance.

“This ultra-cold object is extremely intriguing and we’relearning much more about its true nature with ALMA,” saidRaghvendra Sahai, a researcher and principal scientist at NASA’sJet Propulsion Laboratory in Pasadena, California, and lead authorof a paper published in Astrophysical Journal. “Whatseemed like a double lobe, or boomerang shape, from Earth-basedoptical telescopes, is actually a much broader structure that isexpanding rapidly into space.”

The nebula revealed its true shape to ALMA in the image above.The background blue structure, as seen in visible light by NASA’sHubble Space Telescope, shows a classic double-lobe shape with anarrow central region. ALMA’s resolution and ability to see coldgas molecules reveals the nebula’s more elongated shape, as seen inred.

Additional authors on the paper include Wouter Vlemmings,Chalmers University of Technology, Onsala, Sweden; Patrick Huggins,New York University, New York; Lars-Ake Nyman, Joint ALMAObservatory, Santiago de Chile; and Yiannis Gonidakis, CSIRO,Australia Telescope National Facility.

ALMA, an international astronomy facility, is a partnership ofEurope, North America and East Asia in cooperation with theRepublic of Chile. ALMA construction and operations are led onbehalf of Europe by the European Southern Observatory, on behalf ofNorth America by the National Radio Astronomy Observatory, and onbehalf of East Asia by the National Astronomical Observatory ofJapan.

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