M45昴星團與壯麗的塵埃

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Created for the OAE

Caption: 2022年國際天文學聯合會（IAU）OAE天文攝影比賽靜態天體圖案類別榮譽獎作品。 這張照片於2021年10 月在埃及西奈半島聖凱瑟琳的達爾艾德拍攝，展示了昴星團——一個被俗稱“七姐妹星”的疏散星團。 昴星團位於金牛座的西北部。金牛座源自古巴比倫人甚至蘇美爾人的信仰，它被當時的人們稱為天牛，是天神所擁有的強大生物。在巴比倫晚期，昴星團被稱為“牛背上的鬃毛”。在中國，這個星宿也被稱為“髦頭“，但這並不一定意味著東亞和西亞對這個星宿的稱呼有任何聯繫，儘管有人假設這兩個文明通過絲綢之路的建立而進行了交流。 在古巴比倫的文獻中，並沒有出現將昴星團稱為“毛髮”的記載。相反，昴星團在蘇美爾語中被稱為“星團”，而蘇美爾語中的這個詞被後來的語言作為借詞所引入。蘇美爾和巴比倫早期的宗教將所有星座與特定的神靈聯繫在一起，包括天神、惡魔、神使。昴星團與一位被稱為“七”的冥界神靈有關，被認為是七種會說話的武器或全副武裝的神靈的集合體。後來希臘人將其命名為“七姐妹星”，可能是源於不同文化間對這一古老宗教聯繫的誤解，因為事實上並不能在這個星團中看到七顆星。 昴星團在天空中確實非常顯眼，因此被用於多種文化目的，如確定曆法和春分。然而，在文化天文學中，它的重要性經常被誇大。由於用七個圓點表示昴星團的傳統源於古代蘇美爾信仰，因此將石器時代以來歐洲、亞洲和美洲的洞穴牆壁和考古遺址上的七個圓點解釋為昴宿星團時，我們應該慎重起見。 現代天體物理學發現，昴星團非常年輕，因此在古代肯定沒有額外的恆星。此外，我們還知道，昴星團中所見的明亮恆星只是整個疏散星團的核心區域，該星團其實由散布在天空中的數百顆恆星組成，在任何方向的延展尺度都超過明亮核心的一到兩個直徑。這張照片甚至沒有顯示出整個星團。昴星團距離地球大約400光年，從天文學的角度來說是比較近的。
Credit: Mohamed Usama/IAU OAE

詞彙表術語: 星團 , 梅西耶天體 , 塵埃雲 , 氣體雲 , 星際介質 , 疏散星團 , 昴宿星團
Categories: Milky Way and Interstellar Medium , Naked Eye Astronomy , Stars

License: Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons

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The Horsehead Nebula

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Caption: This image shows the Horsehead Nebula, located at a distance of about 1,300 light-years from Earth in the Orion constellation, one of the most iconic examples of a dark nebula. A dark nebula is a dense cloud of interstellar dust and cold gas that absorbs and scatters visible light, preventing background stars and glowing gas from reaching our eyes. This false-color image combines data captured through multiple narrowband filters, each isolating light from different elements in the nebula. The dark, horse-shaped silhouette appears sharply outlined against the luminous nebula behind it, where energetic radiation from nearby young stars causes the gas to glow. The uneven distribution of visible stars in this image is not random: regions rich in dust in the lower part of this image appear almost empty, while clearer areas reveal many background stars. The dust acts like a cosmic curtain, hiding stars that lie behind it while allowing stars in front of the cloud to remain visible. Studying such regions helps astronomers understand how nebulae serve as environments where new stars can form.
Credit: T.A.Rector (NOIRLab/NSF/AURA) and Hubble Heritage Team (STScI/AURA/NASA)
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詞彙表術語: 暗星雲 , 灰塵 , 星雲 , 空間

License: Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons

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The LDN 483 Dark Nebula

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Caption: This image shows a dark molecular cloud known as LDN 483, captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. At first glance, the patch of sky looks like a region where stars are missing, but the effect is due to interstellar extinction — dust and gas within LDN 483 absorb and scatter light from background stars, making them appear faint or invisible to telescopes that observe visible light. Interstellar extinction is the dimming of light from distant objects caused by dust and gas between the object and the observer, a common phenomenon in astronomy that must be accounted for when measuring stellar brightness and color. Dark nebulae like LDN 483 are dense concentrations of interstellar matter located within our Milky Way Galaxy. This particular cloud lies about 700 light-years from Earth in the constellation Serpens and contains enough material to block most visible light from stars behind it. Because dust grains preferentially scatter shorter (bluer) wavelengths of light, extinction can also make objects appear redder than they truly are — a related effect known as interstellar reddening. Understanding and correcting for extinction is essential for astronomers to reveal the true brightness, distance, and physical properties of celestial objects seen through dusty regions of space.
Credit: ESO
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詞彙表術語: 暗星雲 , 星際介質 , 星際消光

License: Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons

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Dust Clouds and Nebulae near R Coronae Australis

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Caption: The image shows a dark and dusty cloud and some bright reflection nebulae near the binary star R Coronae Australis. The dark cloud spans several light-years and is located in the constellation Corona Australis near the constellation Sagittarius, in the direction of the Milky Way's center. The cloud appears to swallow the light of distant stars behind it as the dust particles in it scatter light passing through in all directions. This gives it the appearance of a void in the sky. This dark nebula is part of the broader Corona Australis Molecular Clouds. R Coronae Australis forms part of the Coronet Cluster, a collection of young stars which formed at some point in the last two million years. Around R Coronae Australis in the center of the image is the small reflection nebula NGC 6729 with two blueish reflection nebulae NGC 6726 and NGC 6727 lying to the upper right of it. In these nebulae the dust scatters light from bright stars near the nebula towards an observer on Earth, making it glow in this image.
Credit: ESO
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詞彙表術語: 暗星雲 , 灰塵 , 星雲 , 星際介質 , 星際消光 , 分子雲
Categories: Milky Way and Interstellar Medium

License: Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons

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Herschel’s view of new stars and molecular clouds

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Caption: This image shows the Westerhout 3, 4 and 5 star formation regions. This area has huge amounts of gas and dust. This gas and dust hides the physical processes going on in this region from studies using visible light. This image was taken in infrared light by the Herschel Space Observatory. This infrared light allowed Herschel to see deep into these star forming regions. In Westerhout 3, 4 and 5, huge, cold clouds of molecular hydrogen have collapsed into dense knots and filaments. Within these new structures the gas is dense and cold enough for it to collapse and form stars. These new stars give off powerful winds of charged particles, like stronger versions of the solar wind our sun gives off. These winds have combined to blow massive bubbles in the surrounding gas and dust. These are visible as the large darker voids in the image.
Credit: ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech)
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詞彙表術語: 紅外天文學 , 恆星形成 , 星際介質 , 分子雲 , 星風
Categories: Milky Way and Interstellar Medium , Stars

License: Creative Commons Attribution 3.0 IGO Creative Commons Attribution 3.0 IGO icons

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