Complex Organic Molecules Found on “Space Hamburger” -- Prebiotic Atmosphere Discovered on Accretion Disk of Baby Star

posted Jun 28, 2017, 6:57 PM by Lauren Huang   [ updated Jun 28, 2017, 8:12 PM by Mei-Yin Chou ]

ASIAA Science Highlight released on 29th, July, 2017

An international research team, led by Chin-Fei Lee of the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA, Taiwan), has used the Atacama Large Millimeter/submillimeter Array (ALMA) to detect complex organic molecules for the first time in the atmosphere of an accretion disk around a very young protostar. These molecules play a crucial role in producing the rich organic chemistry needed for life. The discovery suggests that the building blocks of life are produced in such disks at the very beginning of star formation and that they are available to be incorporated into planets that form in the disk subsequently. It could help us understand how life came to be on Earth.

Figure 1: Jet, disk, and disk atmosphere in the HH 212 protostellar system. (a) A composite image for the HH 212 jet in different molecules, combining the images from the Very Large Telescope (McCaughrean et al. 2002) and ALMA (Lee et al. 2015). Orange image shows the dusty envelope+disk mapped with ALMA.  (b) A zoom-in to the central dusty disk. The asterisk marks the position of the protostar. A size scale of our solar system is shown in the lower right corner for comparison. (c) Atmosphere of the accretion disk detected with ALMA. In the disk atmosphere, green is for deuterated methanol, blue for methanethiol, and red for formamide. Credit: ALMA (ESO/NAOJ/NRAO)/Lee et al.

“It is so exciting to discover complex organic molecules on an accretion disk around a baby star,” says Chin-Fei Lee at ASIAA. “When such molecules were first found in the protoplanetary disk around a star in a later phase of star formation, we wondered if they could have formed earlier. Now, using ALMA’s unprecedented combination of spatial resolution and sensitivity, we not only detect them on a younger accretion disk, but also determine their location. These molecules are the building blocks of life, and they are already there in the disk atmosphere around the baby star in the earliest phase of star formation.”

Figure 2: A 3D cartoon showing an atmosphere of complex organic molecules on an accretion disk. The bluish structure is the accretion disk. The pink layers above and below the disk are the disk atmosphere, in which complex organic molecules including methanol, deuterated methanol, methanethiol, and formamide are detected. For the molecular models, white is hydrogen (H), blue is deuterium (D), black is carbon (C), red is oxygen (O), purple is nitrogen (N), and yellow is sulfur (S). Credit: Lee, C.-F.

Figure 3: Artistic conception of an atmosphere of complex organic molecules on an accretion disk around an embedded baby star with a powerful jet. Credit: ASIAA/ Jung-Shan Chang

Herbig-Haro (HH) 212 is a nearby protostellar system in Orion at a distance of about 1,300 light-years. The central protostar is very young, with an estimated age of only 40,000 years — about 1/100,000th the age of our Sun — and a mass of only 0.2 solar mass. It drives a powerful bipolar jet and thus must accrete material efficiently. Indeed, an accretion disk is seen feeding the protostar. The disk is nearly edge-on and has a radius of about 60 astronomical units (AU), or 60 times the average Earth-Sun distance. Interestingly, it shows a prominent equatorial dark lane sandwiched between two brighter features, looking like a “space hamburger.”

The research team’s ALMA observations have clearly detected an atmosphere of complex organic molecules above and below the disk. These include methanol (CH3OH), deuterated methanol (CH2DOH), methanethiol (CH3SH), and formamide (NH2CHO). These molecules have been proposed to be the precursors for producing biomolecules such as amino acids and sugars. “They are likely formed on icy grains in the disk and then released into the gas phase because of heating from stellar radiation or some other means, such as shocks,” says co-author Zhi-Yun Li of the University of Virginia.

The team’s observations open up an exciting possibility of detecting complex organic molecules in disks around other baby stars through high-resolution and high-sensitivity imaging with ALMA, which provides strong constraints on theories of prebiotic chemistry in star and planet formation. In addition, the observations open up the possibility of detecting more complex organic molecules and biomolecules that could shed light on the origin of life.

Additional information:

Formation and Atmosphere of Complex Organic Molecules of the HH 212 Protostellar Disk,” Chin-Fee Lee et al., 2017 June, to appear in the Astrophysical Journal [http://apj.aas.org, preprint: https://arxiv.org/abs/1706.06041].

The team is composed of Chin-Fei Lee (ASIAA, Taiwan; National Taiwan University, Taiwan), Zhi-Yun Li (University of Virginia, USA), Paul T.P. Ho (ASIAA, Taiwan; East Asia Observatory), Naomi Hirano (ASIAA, Taiwan), Qizhou Zhang (Harvard-Smithsonian Center for Astrophysics, USA) & Hsien Shang (ASIAA, Taiwan).

Media contacts:

Dr. Chin-Fei Lee, Institute of Astrophysics and Astronomy, Academia Sinica cflee@asiaa.sinica.edu.tw    (Tel) +886-2-2366-5445

Dr. Mei-Yin Chou, Institute of Astrophysics and Astronomy, Academia Sinica cmy@asiaa.sinica.edu.tw   (Tel) +886-2-2366-5415


posted Jun 28, 2017, 6:04 PM by Lauren Huang   [ updated Jun 29, 2017, 2:46 AM ]

2017年6月29日 中研院天文所研究成果發表

中央研究院天文及天文物理研究所李景輝國際團隊藉阿塔卡瑪大型毫米及次毫米波陣列 (ALMA) 觀測,首度在原恆星(恆星寶寶)吸積盤(像太空漢堡)的大氣偵測到複合有機分子,這些分子將會形成生命所需的生物分子。由此發現可得知,於恆星形成之初即已形成了生命基本素材,後期可能被帶往在盤面上形成的行星,相關研究啟迪人類對地球生命從何而來的深入認識。



上圖:HH 212原恆星系統之中的噴流、盤、盤面大氣。
的「分子噴流係由不同分子偵測到之噴流,經合成而得影像,影像來自甚大望遠鏡VLT (McCaughrean et al. 2002)和ALMA (Lee et al. 2015)。筆直的分子噴流中間星號位置附近的橘色部分顯示的是ALMA所取得的塵埃包層和盤的影像。
圖右的 (b) 區塊為拉近放大圖,可見以高解析力取得的塵埃盤中心影像。星號標示中心原恆星的位置。右下角是和太陽系大小的比較示意。圖右 (c) 區塊顯示透過ALMA偵測到的吸積盤大氣。大氣中的氘代甲醇以綠色顯示、甲硫醇為藍色、甲醯胺為紅色。圖像版權:ALMA (ESO/NAOJ/NRAO)/ 李景輝團隊

在獵戶座的HH212是鄰近的原恆星系統,距離1300光年。中心原恆星非常年輕,年齡只有4萬年約太陽年齡的十萬分之一),質量也只有太陽五分之一。此原恆星的特徵是發射出強力噴流,物質吸積效率很高。 正在餵食原恆星的吸積盤,以側面角度面向地球,盤的半徑大約60天文單位(1天文單位為太陽到地球的平均距離),中央有一條「暗帶」夾在兩道亮區間,看起來就像太空漢堡」,極為有趣。


上圖:三維繪圖示意吸積盤上大氣所含的複合有機分子。藍色盤面為吸積盤,盤面上下層粉紅色為吸積盤大氣,內含甲醇、 氘代甲醇、甲硫醇和甲醯胺等複合有機分子。分子模型中白色代表氫原子,藍色為氘,黑色是碳,紅色是氧,紫色是氮,黃色是硫。圖像版權:李景輝


研究論文篇名為 Formation and Atmosphere of Complex Organic Molecules of the HH 212 Protostellar Disk”, by Lee et al 於6月27日獲發表於 Astrophysical Journal


Baby Star Spits a “Spinning Jet” As It Munches Down on a “Space Hamburger”

posted Jun 12, 2017, 6:44 AM by Lauren Huang   [ updated Jun 12, 2017, 6:13 PM ]

Science Highlight of ASIAA, Taiwan, June 13th., 2017

Protostellar jets are seen coming out from protostars (baby stars), representing one of the most intriguing signposts of star formation. An international research team, led by Chin-Fei Lee in Academia Sinica Institute of Astronomy and Astrophysics (ASIAA, Taiwan) has made a new breakthrough observation with the Atacama Large Millimeter/submillimeter Array (ALMA), finding a protostellar jet to be spinning, convincingly for the first time. This new result confirms the expected role of the jet in removing the excess angular momentum from the innermost region of an accretion disk (space hamburger), providing a solution to the long-standing problem of how the inner accretion disk can actually feed a protostar.

Figure 1: Jet and disk in the HH 212 protostellar system: (a) Molecular jet (green image) ejected from the innermost part of the accretion disk (orange image), observed with ALMA at a resolution of 8 AU. A dark lane is seen in the disk equator, causing the disk to appear as a “hamburger”. A size scale of our solar system is shown in the lower right corner for size comparison. (b) Split of the redshifted (turning away from us) and blueshifted (turning toward us) emission of the jet in order to show the spinning motion of the jet, as indicated by the green arrows. Blue and red arrows show the rotation of the disk, which has a direction the same as the jet rotation. Credit: ALMA (ESO/NAOJ/NRAO)/Lee et al.


“We see jets coming out from most of baby stars, like a train of bullets speeding down along the rotational axis of the accretion disks. We always wonder what their role is. Are they spinning, as expected in current models of jet launching? However, since the jets are very narrow and their spinning motion is very small, we had not been able to confirm their spinning motion. Now using the ALMA with its unprecedented combination of spatial and velocity resolutions, we not only resolve a jet near a protostar down to 10 AU but also detect its spinning motion”, says Chin-Fei Lee at ASIAA. “It looks like a baby star spits a spinning bullet each time it takes a bite of a space hamburger.”

The central problem in forming a star is the angular momentum in the accretion disk which prevents material from falling into the central protostar. Now with the jet carrying away the excess angular momentum from the material in the innermost region of the disk, the material can readily fall into the central protostar from the disk”, says Paul Ho at ASIAA.

Properties of the Target Source and ALMA Observational Results:

HH 212 is a nearby protostellar system in Orion at a distance of about 1300 ly.  The central protostar is very young with an age of only 40,000 yrs (which is about 10 millionth of the age of Our Sun) and a mass of only 0.2 Msun. Recent ALMA observations at submillimeter wavelength have detected an accretion disk feeding the central protostar. The disk is nearly edge-on and has a radius of about 60 AU. Interestingly, it shows a prominent equatorial dark lane sandwiched between two brighter features, appearing as a “space hamburger”.

The central protostar drives a powerful bipolar jet. Previous observations at a spatial resolution of 140 AU could not confirm a rotation for the jet. Now with ALMA at a resolution of 8 AU, which is about 17 times higher, we zoom in to the innermost part of the jet down to within 10 AU of the central protostar and find a jet rotation. The angular momentum is so small that the jet has to be launched from the innermost region of the disk at about 0.05 AU from the central protostar, well consistent with current models of the jet launching.

Figure 2: A 3D cartoon showing a spinning jet coming out from an accretion disk that feeds the central protostar. (Left) The jet is spinning (as shown by the green arrows), with the blue part turning toward us and the red part turning away from us. In the disk, the blue color is cooler than the orange color. (Right) A zoom-in to the innermost region, showing the possible disk accretion and jet launching processes near the protostar. Our results imply that the jet is launched at about 0.05 AU, as shown by the green arrows. The jet carries away the excess angular momentum, allowing the disk material there to fall into the central protostar, as shown by the blue arrows. As in current jet models, the jet is hollow and higher resolution is needed to check it. Credit: Lee, C.-F.
This new finding indicates that the jet indeed carries away part of the angular momentum (rotational momentum) from the material in the innermost region of the accretion disk (space hamburger), which is rotating around the central protostar. This reduces the rotation of the material there, allowing the disk to feed the central protostar.

Future Prospects:

Our observations open up an exciting possibility of detecting and measuring jet rotation around the protostars through high-resolution imaging with ALMA, which provides strong constraints on theories of jet formation in star formation. In addition, our observations also open up the possibility of detecting jet rotation in other kind of objects, e.g., active nuclei of galaxies, which may play the same role of extracting disk angular momentum as the protostellar jets.

This research was presented in a paper “A Rotating Protostellar Jet Launched from theInnermost Disk of HH 212” by Lee et al. to appear in the journal Nature Astronomy.

The team is composed of Chin-Fei Lee (ASIAA, Taiwan; National Taiwan University, Taiwan), Paul T.P. Ho (ASIAA, Taiwan; East Asia Observatory), Zhi-Yun Li (University of Virginia, USA), Naomi Hirano (ASIAA, Taiwan), Qizhou Zhang (Harvard-Smithsonian Center for Astrophysics, USA), and Hsien Shang (ASIAA, Taiwan).

Additional information:

ALMA also clearly imaged the rotation of a gas outflow from a massive protostar. Please read the press release "ALMA Hears Birth Cry of a Massive Baby Star" from National Astronomical Observatory of Japan.

Media contacts:

Dr. Chin-Fei Lee, Institute of Astrophysics and Astronomy, Academia Sinica cflee@asiaa.sinica.edu.tw    (Tel) +886-2-2366-5445

ALMA首見旋轉式噴流 揭密原恆星成長機制

posted Jun 12, 2017, 6:42 AM by Lauren Huang   [ updated Jun 12, 2017, 7:04 PM ]

2017年6月13日 中研院天文所研究成果發表


圖一:在HH 212原恆星系統裡的噴流和吸積盤。(左圖)顯示從橘色的吸積盤之最內圈盤面,噴出綠色的分子噴流。此圖是ALMA8個天文單位解析力下得到的觀測影像。吸積盤中間有一道暗帶,讓整個盤看起來像個漢堡。左下角以太陽系的海王星公轉軌道為比例尺,供讀者參考了解HH 212的吸積盤大小如何。(右圖)噴流的紅移部份(紅色,譜線紅移代表物體朝我們遠離)和藍移部份(藍色,譜線藍移表示朝我們靠近)分佈在兩側,顯示噴流在轉動(如綠色箭頭所標示)。紅色和藍色箭頭用來標示吸積盤的轉動方向,與噴流一致。圖像版權:ALMA (ESO/NAOJ/NRAO)/中研院天文所李景輝團隊







HH 212是位於獵戶座的一個鄰近原恆星系統,距離大約1300光年。中心的新生恆星誕生迄今僅只有4萬年(是太陽目前年齡的十萬分之一),質量只有太陽五分之一而已。而其中正在餵食原恆星的吸積盤,幾乎以它的側面面對地球,半徑約60個天文單位,盤中間有一道明顯的暗帶,夾在兩個明亮構造之間,這讓它外觀看起來就像個「太空漢堡」。此外,位在系統中心的原恆星還驅動了強而有力的雙極噴流。藉由對此噴流的觀測可進一步探討吸積盤是如何餵食原恆星。







研究論文篇名是 A Rotating Protostellar Jet Launched from the Innermost Disk of HH 212,發表於Nature Astronomy


另篇同時發表於Nature Astronomy 的最新論文,介紹 ALMA取得影像所得見的大質量原恆星氣體慢速噴流(outflow)轉動,是日本國立天文臺的最新成果,相關新聞內容請參考ALMA Hears Birth Cry of a Massive Baby Star



cflee@asiaa.sinica.edu.tw   (02)2366-5445

在新生恆星形成盤裡的塵埃間隙發現旋臂: 暗示行星正在形成!

posted May 24, 2017, 6:45 PM by Lauren Huang   [ updated Jun 8, 2017, 1:12 AM ]

2017年5月22日 中研院天文所研究成果發表



版權: ALMA (ESO/NAOJ/NRAO)/中研院天文所湯雅雯團隊


先前在近紅外波段觀測到的御夫座AB星影像中,旋臂位於本次新觀測到的氣體旋臂內側(更接近恆星)。這可能是由於盤上的氣體旋臂凸起並且有相當的厚度,造成恆星的光大部份在旋臂內側被散射出來,形成近紅外波段看到的旋臂。除了三維空間的資訊,這些氣體旋臂還提供了運動速度的第四維觀點,更有助於了解行星和盤之間的交互作用。旋臂上的氣體運動速度大致上和盤的轉動速度一致,而只有在距離中心恆星30 個天文單位──疑似是行星形成的地方──氣體運動速度比較快,意味著靠近行星的地方,這些氣體繞著行星運轉。

本論文篇名為 Planet Formation in AB Aurigae: Imaging of the Inner Gaseous Spirals Observed inside the Dust Cavity,研究發表於國際性的天文物理期刊(ApJ)。第一作者為中研院天文所湯雅雯博士。


posted May 9, 2017, 10:52 PM by Lauren Huang

原文於2017年5月6日刊載於 網路天文館
All planetesimals born near the Kuiper belt formed as binaries 2017年4月4日刊於 Nature Astronomy,是該論文共同作者之一)




「外太陽系天體起源顏色巡天」(Colours of Outer Solar Systems Origins Survey,簡稱ColOSSOS)是由英國女王大學(Queen's University)的Wesley Fraser領軍,團隊中還包含了來自加拿大、美國、法國及臺灣的天文學家,這是一項結合「外太陽系起源巡天」(Outer Solar Systems Origins Survey,簡稱OSSOS)計畫所發現天體的大型國際合作計畫。研究團隊四月初在《自然天文學》(Nature Astronomy)期刊,發表這項有關太陽系演化的重大研究成果。

天文學家相信,古柏帶(Kuiper belt)是在太陽系演化過程中所留來下的原始小行星帶,由結冰的原始行星盤物質所組成。研究團隊發現有好幾個古柏帶雙微行星表面呈現藍色──這與一般偏紅色的古柏帶天體非常不同。一般推論,藍色雙微行星應該是從離太陽較近的位置移到現今古柏帶處,這個遷移過程大概發生在距今數十億年前,且改變了所有類木行星的軌道。




這項計劃的困難度非常的高--需要同時協調八米的雙子星望遠鏡(Gemini telescope)與四米的加法夏望遠鏡(Canada-French-Hawaii Telescope)進行觀測。就像兩人三腳的比賽一樣,兩台望遠鏡必須要在同時做出相同的操作,觀測同一個天體,如此才算一個成功的觀測,才能消除許多觀測上的誤差。


原始論文請參考:https://www.nature.com/articles/s41550-017-0088  (本文作者陳英同為中研院天文所博士後研究員,論文共同作者之一)


Image Credit: Gemini Observatory/AURA, artwork by Joy Pollard


posted Apr 19, 2017, 6:19 PM by Lauren Huang   [ updated Jun 17, 2017, 10:04 AM by Mei-Yin Chou ]


中研院天文所李景輝團隊利用強大的阿塔卡瑪大型毫米及次毫米波陣列望遠鏡(簡稱ALMA)取得一張超精細的天文影像,捕捉到一顆非常年輕的原恆星(胚胎時期的恆星)正在吸食「塵埃漢堡」—— 一個天文界苦尋多年的最早期塵埃吸積盤。這一項研究確認了在恆星形成初期會形成吸積盤,挑戰現有的吸積盤形成理論。同時也是首度顯示出吸積盤的垂直結構,並對行星形成初期的塵埃顆粒如何長大和沉澱過程提供線索。論文2017419日在Science Advances期刊發表。

圖一:HH212原恆星系統的噴流和盤:(a) 噴流由不同分子偵測到的合成影像,影像來自於甚大望遠鏡VLT (McCaughrean et al. 2002)和ALMA (Lee et al. 2015)。中間橘色部分顯示ALMA於次毫米波段以200個天文單位等級的解析力所取得的塵埃包層和盤的影像。(b) 拉近放大後,可見以8個天文單位的高解析力取得塵埃盤中心影像。星號標示中心原恆星的可能位置,盤中間有一道明顯的暗帶,造成盤子看起來像個漢堡形狀。右下角是和太陽系大小的比較示意,盤子的半徑約為太陽到海王星距離的兩倍。(c) 理論模型推導出的吸積盤溫度分布。圖片版權:ALMA (ESO/NAOJ/NRAO)/Lee et al.



圖二:理論模型推導出的吸積盤影像,和觀測一致:(a) 吸積盤模型的溫度分布。(b)模型推導出的塵埃輻射分布,和觀測到的影像約略一致。圖片版權:Lee et al.





 圖三:插畫示意吸積盤正在餵食中心原恆星,從原恆星有噴流向外噴出。圖片版權:Yin-Chih Tsai/中研院天文所




研究論文篇名:First Detection of Equatorial Dark Dust Lanein a Protostellar Disk at Submillimeter Wavelength” by Lee et al. 於2017年4月19日發表在 Science Advances

研究團隊成員:李景輝 (臺灣中研院天文所臺灣臺灣大學), 李志雲 (美國維吉尼亞大學), 賀曾樸 (臺灣中研院天文所;東亞天文臺), 平野尚美 (臺灣中研院天文所), 張其洲 (美國哈佛史密松天文物理中心), 尚賢 (臺灣中研院天文所)



cflee@asiaa.sinica.edu.tw   (Tel) +886-2-2366-5445


cmy@asiaa.sinica.edu.tw   (Tel) +886-2-2366-5415


posted Apr 5, 2017, 12:47 AM by Lauren Huang   [ updated Apr 10, 2017, 7:57 PM by Mei-Yin Chou ]

Link to the ESO blog


提到事件視界望遠鏡 (EHT) 和全球毫米波特長基線陣列 (GMVA),這是電波望遠鏡之間形成的兩個國際合作計畫連盟,本來,個別都有一群夥伴相連結,各自構成了「和地球一樣大」的「虛擬」望遠鏡,兩者差別僅在於觀測頻段的波長稍微不同,前者是1.3毫米,後者是3毫米。現在,望遠鏡連線更壯觀了,遠自南極延伸抵達歐洲、太平洋上的夏威夷,共同努力的觀測目標就是銀河系中心的超大質量黑洞。


參加全球大連線的電波望遠鏡名稱標示在這張全球地圖上。Credit: ESO/O. Furtak (大圖的連結)



ALMA陣列望遠鏡就是位在照片中這樣的靜僻荒野之境。透過這張全景圖,可以認識ALMA所在位置的地理特徵,是智利安地斯山脈的查南脫高原,海拔高度有5千公尺。Credit: ESO/B. Tafreshi (twanight.org) - http://eso.org/public/images/potw1252a/



黑洞陰影的數值模擬圖:廣義相對論預測陰影應該是像中間圖形那樣,呈圓形,但是黑洞除了圓臉的可能以外,也可能是長臉(如左圖),或寬臉(如右圖)。未來EHT拍到的黑洞陰影影像可以幫我們印證一下。Credit: D. Psaltis and A. Broderick. - http://www.eventhorizontelescope.org/science/general_relativity.html



全球大陣列 , 希望拍到銀河系中心黑洞第一張影像

posted Apr 5, 2017, 12:47 AM by Lauren Huang   [ updated Apr 5, 2017, 12:51 AM ]

圖說:全球擺陣大合作希望能取得第一張黑洞陰影影像! 圖中綠色線條代表EHT網路,黃色則代表GMVA網路。Credit: ESO/O. Furtak

Link to the original ALMA announcement


「全球毫米波特長基線陣列」(Global mm-VLBI Array,縮寫為GMVA) 和「事件視界望遠鏡」 (Event Horizon Telescope,簡稱EHT),各代表十幾個電波望遠鏡成員,就像兩個家族,串連起電波望遠鏡陣列的網路。它們透過一種特殊原理,能把距離幾千公里的多座電波望遠鏡串連成像一個像地球一樣大的望遠鏡,觀測星空。



臺灣在這個在這個全球大合作中有很多貢獻。首先,中央研究院天文及天文物理研究所是東亞天文臺成員之一,此天文臺現在負責運營James Clerk Maxwell望遠鏡(JCMT)望遠鏡,JCMT是一座15米望遠鏡,坐落地點為夏威夷毛納基峰,這個大家或許不太陌生的山峰,同時也是擁有8座天線的「SMA次毫米波陣列望遠鏡」所在之處,中研院天文所並且是SMA的共同合作興建者。此外,臺灣更是ALMA望遠鏡計劃的成員機構。這三座望遠鏡都是EHT網路的一部分。


GMVA 和EHT的觀測將分別於4月1~4日、4月5~14日展開。



巨星周圍不尋常的螺旋 – 中研院ALMA團隊突破天文難題 開創雙星系統研究新頁

posted Mar 2, 2017, 5:13 PM by Lauren Huang   [ updated Mar 3, 2017, 4:18 PM ]


中研院天文及天文物理研究所金孝宣博士主導的國際團隊,以先進的阿塔卡瑪大型毫米及次毫米波陣列望遠鏡 (簡稱ALMA),取得老年恆星飛馬座LL星(LL Pegasi)影像,並使用創新方法推導出其為橢圓軌道的雙星系統,首度突破雙星系統因軌道週期太長而無法直接測量軌道形狀的天文難題。本論文獲發表於三月號Nature Astronomy,並躍登該期封面故事。


圍繞著飛馬座LL星的氣體物質3D觀測影像和模型比較。影片中先出現哈伯太空望遠鏡拍攝到的影像,接著是ALMA觀測到的分子氣體分布,與數值模擬結果比對,形態特徵十分吻合。 版權: Hyosun Kim et al. / I-Ta Hsieh (ASIAA) 

新的ALMA 影像所呈現的螺旋殼層狀圖案特徵,是飛馬座LL星不斷噴發的氣體物質所造成。飛馬座LL星距離地球約3400光年遠,體積比太陽大200倍,正處於恆星演化晚期稱之為紅巨星的階段,而未來我們的太陽也會有類似命運。像飛馬座LL星這樣年老的恆星會噴發大量的恆星風,將其表層氣體與塵埃吹向星際空間中,成為恆星周圍的拱星(circumstellar)物質。將近10年前,哈伯太空望遠鏡取得一張飛馬座LL星的照片,這個天體因為周圍出現前所未聞的、幾近完美的螺旋圖案而大為知名。過去幾年間,天文學家的研究顯示,年老的恆星若有伴星,雙星系統以圓形軌道繞行並交互作用,周圍的拱星氣體便會顯現此螺旋特徵。

() 哈伯太空望遠鏡在2010年發布的飛馬座LL星影像。影像來源: ESA/NASA & R. Sahai () ALMA觀測到的飛馬座LL星的影像。 影像來源: ALMA (ESO/NAOJ/NRAO) / Hyosun Kim et al.

「哈伯太空望遠鏡的影像讓我們欣賞到美麗的旋臂狀結構,但當時照片看到的其實是3維結構投影在 2維上。現在因為有了ALMA的數據,我們得以看到3維立體結構的完整呈現。」共同作者之一, 在美國噴射推進實驗室(JPL)的Raghvendra Sahai博士表示。



研究團隊在由ALMA 最新取得的飛馬座LL星精細圖像中發現螺旋殼層的外觀清楚地呈現分岔。進一步將觀測得到的3維影像與數值模擬結果相比對,首度得出結論認為:此雙星系統具備特別長的橢圓軌道,而非先前認為的圓形軌道,是氣體分布這麼特殊的成因。



飛馬座LL星的ALMA觀測疊加影片 (https://goo.gl/qKDTzk ) 每張圖片顯示不同視線方向的速度(顯示在右上角)下,圍繞著飛馬座LL星的分子氣體物質分布。圖片大小約為太陽到地球距離的2萬倍。版權:ALMA (ESO/NAOJ/NRAO) / Hyosun Kim et al.

國際天文團隊利用阿塔卡瑪大型毫米及次毫米波陣列望遠鏡 (ALMA) ,揭示老年恆星飛馬座 LL星及其伴星為具有橢圓形軌道的雙星系統。本圖顯示出飛馬座 LL星周圍螺旋狀的氣體分布,資料來自於ALMA觀測。研究小組推導出,圖中白色方框內的分岔螺旋特徵,是由長橢圓軌道的雙星系統所造成。成果將於三月號的Nature Astronomy雜誌刊出,並獲選為當期封面故事。圖片來源:ALMA (ESO/NAOJ/NRAO) / Hyosun Kim et al.

國際天文團隊利用阿塔卡瑪大型毫米及次毫米波陣列望遠鏡 (ALMA) ,揭示老年恆星飛馬座 LL星及其伴星為具有橢圓形軌道的雙星系統。本圖顯示出飛馬座 LL星周圍螺旋狀的氣體分布,資料來自於ALMA觀測。研究小組推導出,圖中的分岔螺旋特徵,是由長橢圓軌道的雙星系統所造成。成果將於三月號的Nature Astronomy雜誌刊出,並獲選為當期封面故事。圖片來源:ALMA (ESO/NAOJ/NRAO) / Hyosun Kim et al.

影片從飛馬座拉近看到年老恆星飛馬座LL星。版權: Hyosun Kim (ASIAA)

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