做天文的人在這裡聊﹒天﹒文﹒ 最新調查發現在中央研究院的天文及天文物理研究所，竟有這麼一群人， 一心想對一般大眾介紹自己的研究現況，樂意分享為什麼浸沉其中的妙趣故事！ 所以，不講公式 只說故事， 從這裡出發，讓既深奧又引人好奇的天文來距離大家更近一點
Language
🇨🇳
Publishing Since
3/25/2021
Email Addresses
1 available
Phone Numbers
0 available
April 21, 2022
這裡沒有張惠妹的歌「站在高崗上」提到的綠波海茫茫，在這裡只有黃土茫茫，而且缺氧。 由天文所主導之為阿塔卡瑪大型毫米及次毫米波陣列（簡稱”ALMA”）研發的「第一頻段接收機」於2016年被採用，並已於2021年開始接受訊號，聽聽科學家如何努力的刻服惡劣環境，堅持至今。努力工作時，又看到了哪些有趣的動物呢？且聽分曉。 背景音樂由 audionautix.com 提供
July 16, 2021
數月之後，隨著一座最新太空望遠鏡的發射升空，由天文學家精心設計的觀測計畫也將在離地球150萬公里的太空中開始付諸實踐，到底會發現什麼？仰望星空，令人引頸期待。其中的一份觀測計畫，是來自臺灣中研院天文所博士後研究 Dr. Sascha Zeegers（諸葛沙夏）團隊的提案。 本集節目中，沙夏要告訴我們，她為什麼醉心投入宇宙塵埃這個研究主題、她的期待與展望；不可少的，也聊一下這個大家已經等了20年的韋伯太空望遠鏡，可以用來做什麼。 本集內容為英語。 背景音樂由 audionautix.com 提供 Transcription: Welcome to the Astronomy Podcast produced by Academia Sinica Institute of Astronomy and Astrophysics I am show host of today, Lauren Huang. And, we are having our postdoc fellow Dr. Sascha Zeegers here with us. Hi, Sascha, we know that a space telescope is going to be launched into the space later this year, and, you're one of those who got the observation time to use it. Would you please explain for us what is this telescope aiming to do? Thank you Lauren. So the James Webb Telescope, which we also call JWST or Webb for short, will be the largest telescope that we ever send into Space. The whole telescope will be roughly as large as a tennis court. The mirror is 6.5 m in diameter. This telescope will be launched in October of this year. Because it is such a big telescope with very sensitive instruments it can observe things we have never been able to see before. We may be able to observe the atmospheres of exoplanets, look inside clouds of gas and dust and observe how stars are born. We can also look at the youngest, most far away galaxies in the universe and learn a lot more about the history of the universe. Is it going to replace HST? So I guess the answer to that is yes and no. We often compare this telescope to the Hubble space telescope, but the two telescopes are actually quite different. JWST is an infrared telescope, so it looks at the universe at a longer or redder wavelength. Hubble is more optimized at the wavelength where our eyes can see and the ultraviolet. This longer wavelength enables JWST to look inside molecular clouds to see how stars are born and it can explore the early universe and the youngest galaxies further. Hubble is still an amazing telescope though and to make our observations more complete over the spectrum we also requested time to observe with Hubble. How long will this JWST telescope fly…? We are usually cautious to say what the lifespan of the telescope will be, since we don't exactly know. Things may go wrong, although very often space telescopes operate far longer than expected. Hubble has been flying for around 30 years already. We think that JWST should be able to operate for some time between 5.5 to 10 years and perhaps longer. It is certainly shorter than Hubble, since the mission is limited by the supply of hydrazine fuel needed to maintain the spacecraft’s orbit. It will also operate much further from Earth (1.5 million km), so unlike what was done with Hubble, we can't just go to the telescope and fix things which are not working properly. That is why people have done long and extensive tests on JWST from Earth. How many people from Taiwan are involved in the proposals that that got the selected time of this round so there are three proposals from people in Taiwan that got accepted so one of them is someone from another university so not from our institute from ASIAA. But within ASIAA we have two people who are the principal investigator of a project so there are two different projects. And the project I work on and I'm the principal investigator of, there are two other people also working at ASIAA, Jointy Marshall and Ciska Kemper who are also involved in this project. It's called co-investigators. So, you're leading the team? I'm reading the team yeah. I heard some people said that the competition for this JWST time is quite fierce, do you think so? I think so yeah. It was quite fierce. It was also because there is this big anticipation we've been looking forward to doing science with this telescope for maybe two decades already. Also the expectations are super high. So now this is the first time people could submit their projects and everyone wants their project to be accepted of course. So the telescope is "over-subscribed" and there are different types of projects related to the amount of time you request to observe -- so there are small proposals, medium and large proposals. And in my category, which is a medium proposal, the oversubscription was about five to one -- so only one out of five submitted proposals would get selected. WOW! congratulations! Thank you So what was the immediate thought when you learned that you've won? Was it like -- I know it's coming to me! Or you more like -- ahh! winning a lottery!!! So what happens is that you know roughly when the day comes that they announce it. But still when they send out all the emails with the yeah accepted and rejected proposals it's still a surprise so here in Taiwan we're a bit ahead in in the day compared to the us of course so they send it at the for them normal time in the in in the morning but for me came here at midnight so i saw this email and then it's it's it's like it's yeah unbelievable when you open that email and they say your proposal is accepted. So. yeah. It's not like winning the lottery because the odds are much higher of course, but it does feel like winning the lottery yeah. It was fantastic. And then you think oh wow okay so now really this project is going to happen, so we have to arrange lots of things. Yeah, so the immediate thought is: wow! So now tell us about your research! What in this cosmic dust is fascinating you in the first place? and by now what are you studying? I will use JWST to observe cosmic dust. This is dust produced in the atmospheres of old stars. The stellar wind then injects it in space, the interstellar medium. The fascinating thing about cosmic dust is that you can find it everywhere in the universe, even in the most far away Galaxies. It is also very important, because a lot of processes in the universe happen thanks to this dust. The most important reason to study it, is because we and everything around us is made of this star dust. So if we want to study life in the universe, we need to study the properties of stardust. That's fantastic! Sascha, can you recall at what age you first time learned about "we are all made of dust"? That's a hard question. I don't know. A lot of people they've watched this program… "the Cosmos"! so yeah there is this. But i think if you're in Europe you don't really know about that program. I grew up in Europe. But there is this program the Cosmos and the first edition of that was by Carl Sagan, in 80s, and he in his his program he said "we're all made of stardust" so yeah that's like the the thing that people cite the most. But i think my realization came much later when i heard when i learned that stars produce elements, and then i was like okay, so everything is produced by stars. And later on I learned about that stars produced dust and that that dust is the stuff that gets injected into our solar system and finally created everything that's around us. So I think it's a more of a gradual realization than like… Around the age of 11, 12 years old, then i learned that stars produced elements. And i was like, wow, okay, so everything comes from stars. But yeah the realization that there is dust floating around in space, that claim, I learned about that much later. So yeah, dust from the interstellar medium gives us the starting conditions for solar systems, so if you want to understand how our own solar system formed, we need to know the properties of this cosmic dust, and what the starting point, starting conditions for our solar system were. The dust from the interstellar medium gives us the starting conditions of solar systems. If we want to understand our own solar system and how it is formed, we need to know what the properties of this cosmic dust are! So this is what I am interested in. i want to find out what happens to the dust in space so when it floats between the stars because there it gets bombarded by radiation and particles that change the dust. And at the moment we don't really know why dust survives this environment at all and how it ends up in planets eventually. So we need to study the properties of the of these dust particles, so for instance, whether they are crystalline or whether they are completely amorphous, or what the chemical composition is, and how large these grains are. With JWST we will look at stars in the Galaxy and observe how part of the light from the stars gets absorbed by dust along the line of sight before it reaches us. Every type of dust has its own particular pattern in which it absorbs the light and from that we can derive what kind of dust we are looking at. Yeah so the reason I'm fascinated by it is that we're all made of stardust. And we really have so many questions yet to answer to get to the point of how did everything especially also the earth form and life started. So this is going to answer the big question about origin. Yeah it will be one part of the answer in the origin and the life cycle of stars in the universe. Will you count this one one of your greatest achievements when maybe looking back in 10 years of time from now? Do you think? JWST has the precision to answer many of our questions. It will be the first time we can look at the universe in this precise way and we have been anticipating it for years. I am sure that whatever we may find, it will be very exciting and that I will look back on the achievements of the team with a lot of joy. Right! How this is going to affect the astronomers of Taiwan do you think or uh how they affect the next generation scientists of Taiwan? So yeah i hope that we can involve more people in this type of research and that it will give the research about cosmic dust a big boost especially here in Taiwan because we have people working on that within this institute but also all over Taiwan and for yeah for infrared astronomy in Taiwan this will be great so the infrared astronomers that are looking at this specific wavelength will benefit from this research but also anyone else that uses dust models in their research will benefit from from this research project so hopefully it will also raise many questions and new projects and new things for people to work on also for students in Taiwan so yeah it's a it's an exciting time for people here Wonderful! Lastly, what results of your observation are we expecting? and when? we can make predictions of what we may find and what it means of course for instance if we find dust particles that are crystalline they may be recently produced by stars and if they are small they may be shattered and perhaps the dust is different in different environments so the composition changes slightly on which way we look. And perhaps not a yeah and perhaps the there will be surprises something that we really really didn't expect. Because yeah we are studying the dust in this environment of the galaxy for the very very first time. so yeah we always have to be prepared for something completely unexpected which is difficult um yeah it will take some time before we get results because first the telescope needs to be launched, then it needs to be moved into position, and then there is a phase where they will test the instruments very carefully, and after that time so that's about six months after the launch, then observations are starting to take place, but we are observing quite a large number of stars, so these observations they will trickle in in like they will come in slowly off in the course of a year. um and then we need time to study the results or the observations and reduce the data so this whole process easily takes up two or three years. Right. Very well! so good luck with the observation time! Thank you. We look forward to your exciting new results! I think there will be lot lots of news coming out from James Webb around that time from many projects! Yes! Nice work! See you next time!
June 10, 2021
"地球並不孤單，地球／太陽也不只我們這一組。"這情境，現代人都一清二楚，並不稀奇，但哲學家伊比鳩魯和鄧牧，早分別在西元前3百年和中國的元代都已想到過了，那可算是真厲害。至於，製作出一台望遠鏡來放眼向太空瞭望看看，那就比較更近代一點，已經是第17世紀的事了。 中研院天文所的 Dr. Gilles Otten 幫大家整理這段太陽系外行星從哲學走到科學之路。並解說為什麼非要用望遠鏡直接地看到單一行星不可，理由何在？到底有多難呢？目前為止有哪些技術困難已克服？最大的光學望遠鏡現在蓋到哪兒了？何時能啟用？聽說臺灣也有幫忙貢獻，是嗎？ 本集內容為英語。 In this episode, Dr. Otten very briefly summarized how people thought about the issue of "planets around other stars" since millenniums ago. Also, he will tell us, who firstly coined the word "exoplanet"? Is it easy or hard to discover exoplanets? What are the challenges needed to be solved in order to photograph exoplanets? What technical terms like Diffraction limit, Adaptive Optics and Coronagraph actually mean? What are the current status of the biggest telescopes? Does Taiwan play a role? Transcribe: Welcome to Astronomy Podcast produced by Academia Sinica Institute of Astronomy and Astrophysics, or A-S-I-A-A, "ASIA A", a shorten name. Today’s show host: Lauren Huang. We are having Dr. Gilles Otten with us. Gilles is working for ASIAA, in Taiwan, helps building one of the world’s biggest telescope, and today he will tell us about Direct imaging exoplanet around another star. Hi, Gilles, thank you for coming in the middle of a pandemic. Thank you. Well, let's start the show! First question, since a long time ago people have thought about planets around other stars. Indeed a long, interesting history about discovering. Important questions we asked and always still want to ask. Gilles, how about… a summarization? Sure. So there are a lot of written examples of philosophers who have wondered about the existence of planets around other stars. So, for instance, in the third century BC there was a Greek philosopher named Epicurus （伊比鳩魯）who thought there would be an unlimited amount of worlds and even in the 13th century there were philosophers such as the Chinese philosopher Deng Mu (鄧牧) who said it would be unreasonable to assume that there are no other worlds beyond our own. So this is uh…, it sounds almost like science fiction if you look back at it. And some of these philosophers even speculated about life on other planets. But now in the present day with the modern science we can of course form more structured questions than they ever could, like: is the role, the position of our earth unique or eventually we can probably answer this ultimate question whether there's life on other planets using scientific methods, which of course these philosophers never had. Right, when did modern astronomers start responding to all of these questions and, what did they do? So only after the first telescopes were invented in the early 17th century things really started to become more scientific. So just -I think- a few years or maybe even in the year after they invented the telescope Galileo Galilei discovered the first moons orbiting Jupiter and seeing this miniature solar system almost orbiting as if it was a tiny solar system like our own. It kind of validated the earlier philosophical comments. So yeah when you realize the earth and its moon are not really in a unique situation, you can really believe that all stars could have planets on their own and of course it didn't stop people from philosophizing, even scientists they can philosophize, but through the invention of this first telescope the first steps were made to this modern astronomy and the eventual discovery of exoplanets only 30 years ago. So, who invented this word “exoplanet”? Which word do you use in the place where you're from? Is it easy or hard to discover exoplanets? Yeah so i looked a bit into the history of the exoplanets and how long have people been searching for exoplanets. And even though i think already in the 19th century people were trying to discover extra-solar planets but they would call it a planet around another star or a potential companion and in the end none of these discoveries turned out to be a real exoplanet. But the earliest reference that i could find is from 1943 where a team of astronomers in the US under the director Peter van de Kamp said that they discovered a planet around a star 61 Cygni because they had seen wobbles in the motion of this star. And their team has made many such claims of many exoplanets and maybe they even invented the word or first mentioned the word in a scientific paper. But in the 1970s all of these claims were proven to be just a measurement mistake, a systematic error. But yeah where i'm from in the Netherlands, we use a similar word as exoplanet “exoplaneet” but there's also an other word that people use buitenaardse planeet which means extraterrestrial planet. So after the 70s only in the late 80s the first reasonably convincing discoveries were made of exoplanets. But people were still skeptical in the late 80s and the beginning of the 90s. Until 1992, then there was a discovery by (Aleksander) Wolszczan and (Dale) Frail of a planet around a dead star so-called pulsar with a planet, and the field of extra-solar planet research it really kicked off just after 1995 when they discovered a Jupiter-sized planet around a sun-like star by the team (Michel) Mayor and (Didier) Queloz and since then many thousands of exoplanets have been discovered using various different methods: the radial velocity method, the planetary transit technique, and microlensing, for instance. And up to 2004, exoplanets had only been discovered with these indirect methods, and mostly they discovered planets very close to their stars. So only in 2004, they were able to discover the first exoplanet directly in an orbit around a “Brown Dwarf”. And a brown dwarf, it's such a small star that it doesn't even have nuclear fusion. So because it was so difficult to see it around the regular star the first objects they found directly image planets around was a brown dwarf. And since then only a few dozen exoplanets have been directly imaged, so it's quite challenging. What challenges needed to be solved in order to photograph exoplanets? So there are multiple challenges when it comes to directly imaging exoplanets and that's also one of the reasons why it took so long after the first discovery before they they could photograph one directly. The first challenge is that you need to separate the starlight physically from the planet light, so they are seen as two distinct objects instead of just one blurred together object. And then secondly you need to correct the turbulence of earth's atmosphere that would otherwise distort your images when you're observing using ground-based telescopes. And thirdly, you need to suppress the starlight because your starlight can very easily overwhelm the light that you can get from the planet. So it would be ideal if you could somehow switch off the star so you can only get the light from the planet. But yeah we have some we have to use some clever optical tricks to do this. And lastly when you have removed your star light you still need to clean up your images by using all kinds of software techniques to get rid of this last remaining starlight and really reveal the planet. What is your research interest? So i did my PhD on coronagraphs which is exactly the method you suppress starlight with. I'm interested in all kinds of instrumental approaches to help support the discovery and the detection of these extrasolar planets. Very interesting! Any technical terms we need to know before going into further details? …diffraction limits? “adaptive optics”? yeah so, here for instance, to separate the starlight from planet light, we have to deal with the physical limits of an optical system, and this is called the “diffraction limit”. So the diffraction limit is the smallest angular scale that we can see with any optical system whether it's your eyes or a telescope and for the biggest telescopes we have right now if you're looking at the nearest stars this diffraction limit can easily be the same angular size as the size that we see; well the size of the planetary system that we see. So if you want to reduce the size of this diffraction limit we have to build even bigger telescopes, even bigger than the like the 10-meter-wide telescopes that we're building nowadays. Now the other thing the to correct this turbulence of the earth's atmosphere and the twinkling of the stars that you see at night. We use something called an “adaptive optic” system and it consists out of three components. First of all, a deformable mirror, secondly a wavefront sensor, and thirdly, a control system like an advanced computer, and together these three components they very rapidly measure the distortion that the earth's atmosphere -the turbulence in the earth's atmosphere- induces in our stars and in our planet image and then it uses a deformable mirror like a very thin mirror with all kinds of fingers on the back to [push on] and the mirror can therefore assume any shape and then they can correct the shape of the light a thousand times per second and only with this correction we can reach the diffraction limit from the ground. But now this actually almost routinely occurs in the major telescopes around the world and these telescopes can actually obtain sharper images than even the Hubble Space Telescope. So yeah and to cover these coronagraphs -- these starlight-suppressing devices that i mentioned that i worked on in the past, so they are there to reduce the amount of starlight at the location of the planet, so if we are looking for earth-like planets around a star like our sun then we need to be able to overcome a contrast difference of 10 billion to one. And the most intuitive form of a coronagraph it's called a Lyot coronagraph which is almost like sticking your arm out and putting your thumb on the star to be able to see the planet! And lastly, as i already said, astronomers use a lot of software techniques and a lot of the progress in the last 10 years has been made in that area. So a lot of new discoveries of planets, even around stars that we knew already had planets, they come from these better software techniques and the easiest way to do this with a computer would be to take two images: one of a star that you think might have a planet, and another picture of another star nearby which might not have a planet. And if you subtract the two images then you're left with mostly the planetlight. So that's a very basic approach. So these four techniques simply explained, they are the basis of many of these discoveries. Right, so what are the current status of the biggest telescopes? Yeah, so of course we want to build bigger telescopes, not just to be able to gather more light so we can see fainter objects, but for direct imaging of exoplanets we really need the bigger telescopes to be able to resolve planets close to the stars. So to be able to say that there actually are two objects next to each other not just one big merged blob. Yes. And currently there are about three extremely large telescopes under development in the world. So, “extremely large” means it's like the next generation, about three to four times as big as the current record holder. And these three telescopes are called the “Giant Magellan Telescope”, “the 30 Meter Telescope” which both are about 25 to 30 meters. And then the third one is called “the Extremely Large Telescope” which will become 39 meters in diameter. And for two of these telescopes they're actually already building, they're building them. So in the coming five to ten years you will start to see more images of them being constructed and around 2025 2026 we should be able to use them. And Taiwan plays an important role in this 39 meter wide Extremely Large Telescope. So there's an instrument in development it's called METIS and it will do this direct imaging of exoplanets. So, which… I mean it will not only discover new planets but it will also be able to do a detailed characterization of the atmospheres of these planets. And even for the nearest stars this instrument and telescope are sensitive enough to discover Earth-like planets. Taiwan contributes both to the mechanical part of this instrument and also in the scientific build-up and Taiwan will sit in the front row when the first scientific results come in on these planets. Really cool! Look forward to more news of your progress. Hopefully soon we will find a whole new world of better things waiting ahead. See you next time. 背景音樂由 audionautix.com 提供
Pod Engine is not affiliated with, endorsed by, or officially connected with any of the podcasts displayed on this platform. We operate independently as a podcast discovery and analytics service.
All podcast artwork, thumbnails, and content displayed on this page are the property of their respective owners and are protected by applicable copyright laws. This includes, but is not limited to, podcast cover art, episode artwork, show descriptions, episode titles, transcripts, audio snippets, and any other content originating from the podcast creators or their licensors.
We display this content under fair use principles and/or implied license for the purpose of podcast discovery, information, and commentary. We make no claim of ownership over any podcast content, artwork, or related materials shown on this platform. All trademarks, service marks, and trade names are the property of their respective owners.
While we strive to ensure all content usage is properly authorized, if you are a rights holder and believe your content is being used inappropriately or without proper authorization, please contact us immediately at [email protected] for prompt review and appropriate action, which may include content removal or proper attribution.
By accessing and using this platform, you acknowledge and agree to respect all applicable copyright laws and intellectual property rights of content owners. Any unauthorized reproduction, distribution, or commercial use of the content displayed on this platform is strictly prohibited.
