美國宇航局在銀河系中心發(fā)現(xiàn)“宇宙拐杖糖”

美國宇航局在銀河系中心發(fā)現(xiàn)“宇宙拐杖糖”

Here's a holiday card from 27,000 light-years away, offering a little yuletide cheer and astronomical intrigue from the mysterious central zone of the Milky Way. The composite image above shows an enormous swath of the galactic center, spanning about 750 light-years across, where a giant "cosmic candy cane" stands out among colorful molecular clouds.

這是一張27000光年外的節(jié)日賀卡，上面有來自銀河系神秘中心地帶的一點圣誕節(jié)的歡樂和天文學的神秘。上面的合成圖像顯示了銀河系中心的一條巨大的狹長地帶，橫跨約750光年，其中一個巨大的“宇宙拐杖糖”在彩色分子云中脫穎而出。

Photo: NASA’s Goddard Space Flight Center

This festive scene was captured by a NASA camera, the Goddard-IRAM Superconducting 2-Millimeter Observer (GISMO). It's the subject of two scientific studies — one led by Johannes Staguhn of Johns Hopkins University, and one led by Richard Arendt at the University of Maryland — both recently published in The Astrophysical Journal.

這一喜慶的場景是由美國宇航局的一臺名為Goddard-IRAM超導2毫米觀測者(GISMO)的照相機拍攝的。這是兩項科學研究的主題——一項由約翰霍普金斯大學的約翰內(nèi)斯·斯塔古恩領導，另一項由馬里蘭大學的理查德·阿倫特領導——兩項研究最近都發(fā)表在《天體物理學雜志》上。

The image offers a rare glimpse into the bustling downtown Milky Way, home to the largest and densest collection of molecular clouds in our galaxy. These cold, colossal structures can give birth to new stars, and the molecular clouds in this image hold enough dense gas and dust to form tens of millions of stars like our sun, according to NASA.

這張照片為我們提供了一個難得的機會，讓我們得以一窺熙熙攘攘的銀河系中心，這里是我們星系中分子云最龐大、密度最大的地方。據(jù)美國國家航空航天局稱，這些冰冷、巨大的結構可以孕育出新的恒星，而這幅圖像中的分子云含有足夠的稠密氣體和塵埃，足以形成數(shù)千萬顆像我們的太陽一樣的恒星。

"The galactic center is an enigmatic region with extreme conditions where velocities are higher and objects frequently collide with one another," says Staguhn, a research scientist at Johns Hopkins who also leads the GISMO team at NASA's Goddard Space Flight Center, in a statement. "GISMO gives us the opportunity to observe microwaves with a wavelength of 2 millimeters at a large scale, combined with an angular resolution that perfectly matches the size of galactic center features we are interested in. Such detailed, large-scale observations have never been done before."

“銀河系中心是一個神秘的區(qū)域，在極端條件下，速度更高，物體之間經(jīng)常發(fā)生碰撞，”約翰霍普金斯大學的研究科學家斯塔格恩在一份聲明中說，他同時也是美國宇航局戈達德太空飛行中心GISMO團隊的負責人。“GISMO讓我們有機會在大尺度上觀察到波長為2毫米的微波，再加上與我們感興趣的星系中心特征大小完美匹配的角度分辨率。如此詳細、大規(guī)模的觀測是前所未有的。”

That "candy cane" in the center of the image is made of ionized gas and measures 190 light-years from end to end, NASA explains in a news release. It includes a prominent radio filament known as the Radio Arc, which forms the straight part of the candy cane, as well as filaments known as the Sickle and the Arches, which form the cane's handle.

NASA在新聞發(fā)布會上解釋說，圖片中心的“拐杖糖”是由電離氣體構成的，從一端到另一端長達190光年。它包括一個著名的被稱為無線電弧的無線電燈絲，它形成了“拐杖糖”的直線部分，以及被稱為鐮刀和拱門的燈絲，它形成了“拐杖糖”的手柄。

This labeled version of the GISMO image highlights the Arches, Sickle and Radio Arc that form a 'cosmic candy cane,' as well as other key features like Sagittarius A, home to a supermassive black hole at the center of our galaxy. (Image: NASA’s Goddard Space Flight Center)

GISMO gathered enough data to detect the Radio Arc after gazing into the sky for eight hours, making this the shortest wavelength where these strange structures have been observed by humans. These radio filaments mark the edges of a large bubble, researchers say, which was produced by some kind of energetic event at the galactic center.

在凝視天空8個小時后，GISMO收集了足夠的數(shù)據(jù)來探測射電弧，使其成為人類觀測到的這些奇怪結構的最短波長。研究人員說，這些無線電絲標記著一個大氣泡的邊緣，這個大氣泡是由銀河系中心的某種高能事件產(chǎn)生的。

The new microwave observations from GISMO are portrayed in green, for example, while blue and cyan reveal cold dust in molecular clouds where "star formation is still in its infancy," NASA explains. In yellow regions like the Arches or the Sagittarius B1 molecular cloud, we're looking at ionized gas in well-developed "star factories," courtesy of light from electrons that are slowed but not captured by the gas ions. Red and orange represent "synchrotron emission" in features like the Radio Arc and Sagittarius A, a bright region inhabited by a supermassive black hole.

例如，來自GISMO的新微波觀測結果被描繪成綠色，而藍色和青色顯示了分子云中的冷塵埃，NASA解釋說，“恒星形成仍處于初期階段”。在像拱門或人馬座B1分子云這樣的黃色區(qū)域，我們看到的是在成熟的“恒星工廠”里的電離氣體，這是由于電子減慢了速度，但沒有被氣體離子捕獲。在射電弧和人馬座A(一個由超大質量黑洞居住的明亮區(qū)域)等特征中，紅色和橙色代表“同步加速發(fā)射”。

This image shows another view of the galactic center, thanks to infrared cameras on the Spitzer Space Telescope. (Image: Susan Stolovy (SSC/Caltech) et al./NASA, JPL-Caltech)

The center of our galaxy is largely obscured by clouds of dust and gas, preventing us from directly observing scenes like this with optical telescopes. We can still peek in other formats, though, such as infrared light — used by NASA's Spitzer Space Telescope, for instance, and the upcoming James Webb Space Telescope — or radio waves, including the microwaves detected by GISMO.

我們星系的中心很大程度上被塵埃和氣體云所遮蔽，使我們無法用光學望遠鏡直接觀測到這樣的景象。盡管如此，我們?nèi)匀豢梢酝ㄟ^其他方式進行觀測，比如美國宇航局的斯皮策太空望遠鏡使用的紅外線，以及即將推出的詹姆斯韋伯太空望遠鏡，或者無線電波，包括GISMO探測到的微波。

In future missions, GISMO may help us see even deeper in space. Staguhn hopes to take GISMO to the Greenland Telescope, where it could produce vast sky surveys in search of the first galaxies where stars formed.

在未來的任務中，GISMO可能會幫助我們看得更遠。斯塔格恩希望將GISMO帶到格陵蘭島望遠鏡，在那里它可以進行大規(guī)模的天空觀測，尋找第一個恒星形成的星系。

"There's a good chance that a significant part of star formation that occurred during the universe's infancy is obscured and can't be detected by tools we've been using," Staguhn says, "and GISMO will be able to help detect what was previously unobservable."

斯塔格恩說:“很有可能，發(fā)生在宇宙初期的恒星形成的重要部分被我們一直使用的工具所掩蓋，無法被探測到。而GISMO將能夠幫助探測到以前無法觀測到的東西。”