您现在的位置是:主页 > 美高梅app客户端下载 > 太陽將變成尋找系外行星的放大鏡

太陽將變成尋找系外行星的放大鏡
2020-01-11 18:04   来源:  www.alemdojogo.com   评论:0 点击:

太陽將變成尋找系外行星的放大鏡近日,美国宇航局喷气推进实验室和美国航太公司联合研究出了利用太阳引力透

  近日,美国宇航局喷气推进实验室和美国航太公司联合研究出了利用太阳引力透镜(SGL)探测系外行星的方法。这一方法引起了不少人的兴趣,那么它真的可行吗?一起来看看吧~

Recently, NASA's Jet Propulsion Laboratory and NASA have teamed up to work out ways to use the Sun's gravitational lens (SGL) to detect exoplanets. This method has attracted a lot of interest, so is it really feasible? Let's have a look ~

  前段时间,新闻中热炒美国宇航局计划用太阳作为引力透镜,对系外行星成像,事实上在2017年这个计划就已经提出来了[1]。有人觉得这是个不错的新奇想法,也有研究轨道动力学的同事质疑这样的观测是不现实的。但这条新闻却让我想起了多年前听过的一个同样新奇的报告。

Some time ago, NASA's plan to use the sun as a gravitational lens for imaging exoplanets was hyped in the news, and in fact the plan has been proposed in 2017[1]. Some say it's a good novelty, and some colleagues who study orbital dynamics question that such observations are unrealistic. But the news reminded me of an equally novel report I heard years ago.

  广义相对论指出,光在引力场中发生偏折[2]。故而,广义相对论的一个观测检验就是星光经过太阳附近时的偏折。直到现在,天文学家仍然在测量太阳对电磁波的偏折,只是不再观测恒星的位置,而是通过甚长基线干涉观测射电源的位置[3]。

General relativity points out that light folds in the gravitational field [2]. Thus, an observational test of general relativity is the deflection of starlight as it passes near the sun. Until now, astronomers are still measuring the sun's deflection of electromagnetic waves, only to stop observing the position of the star, but to observe the position of the power through very long baseline interference [3].

  光在被天体的引力场偏折在天文中是普遍存在的现象,包括众所周知的星系或星系团造就的强引力透镜以及行星(或者某种未知天体)等产生的微引力透镜。太阳自然也是可以作为引力透镜的,前段时间热炒的新闻就是美国宇航局计划用太阳作为引力透镜,对系外行星成像[4]。

Light is common in astronomy when it is deflected by the gravitational field of an object, including the well-known force lens created by galaxies or clusters, and the micro-force lens created by planets (or some unknown object). The sun can also be used as a gravitational lens, and the hot news of the previous period is that NASA plans to use the sun as a gravitational lens for imaging exoplanets [4].

  用太阳作为引力透镜成像看上去是一个新想法,但用太阳作为引力透镜,我在2011年10月24日听研究SETI(搜索外星文明)的ClaudioMaccone博士的报告时就了解到这个想法了。Maccone博士当时的报告题目是“FOCALspacemissionto550AUandbeyond”,比较吸引我的就是550AU这个值。Turyshev等人的文献里给出的是548AU。两个值比较接近,这是怎么来的呢?

Imaging with the sun as a gravitational lens may seem like a new idea, but using the sun as a gravitational lens, I learned that idea on October 24,2011, when I listened to a report by Dr. Claudio Mackone, who studies SETI (searching for alien civilizations). Dr. Maccone's report at the time was titled \"FOCALspacemissionto550AUandbeyond,\" and I was more attracted to the 550-AU value. Turyshev et al.'s literature gives 548AU. How did this come about when the two values were close?

  可以简单计算一下,光在质量为M的半径为r天体的引力场中的偏转角和天体的质量M成正比,和天体的半径r成反比。另外一方面,这个偏转角度可以近似为天体半径r和焦距d的比值。因此,对于给定的天体,以它为透镜得到的焦距和天体半径r的平方成正比,和天体质量M成反比。通过仔细思考和计算,你会发现一个有趣的事实,如果用太阳系中的天体做引力透镜,太阳的焦距最小,就是550AU左右!

It can be simply calculated that the deflection angle of light in the gravitational field with a radius of mass M r is proportional to the mass M of the celestial body and inversely proportional to the radius r of the celestial body. on the other hand, this deflection angle can be approximated as the ratio of the celestial radius r to the focal length d. Therefore, for a given object, the focal length obtained with it as a lens is proportional to the square of the radius r of the celestial body and inversely proportional to the mass M of the celestial body. Through careful thinking and calculation, you will find an interesting fact that if the celestial body in the solar system is used as a gravitational lens, the focal length of the sun is the smallest, which is about 550AU!

图2。将太阳作为引力透镜的探测卫星所在轨道。也就是说,如果要放一台探测卫星,利用太阳作为透镜,探测远方天体,那么这颗卫星所在的轨道的半径应该是550AU,就是图中所示的位置。(图片来源:NASA)

Figure 2. The orbit of a probe satellite that uses the sun as a gravitational lens. That is, if a probe satellite is to be placed, using the sun as a lens to probe distant objects, then the radius of the orbit of the satellite should be 550 AU, the position shown in the diagram. (Photo: NASA)

  Turyshev等人的想法是在距离太阳550AU左右的地方放一颗卫星对系外行星成像。而早先Macccne博士的想法是在距离太阳550AU左右的地方放一个天线,接收来自天体的信号,或者发射信号,把太阳作为一个放大器。如果我们要发射一艘太空飞船前往距离太阳最近的恒星,这可能是不多的让这艘飞船与我们保持通讯联系的方案。在550AU半径的轨道,周期大约为一万两千多年,在这个轨道上的卫星或天线一年运动10角秒,在一年内瞄准一个方向是有可能的。

The idea for Turyshev et al is to put a satellite to image exoplanets around 550 AU from the sun. Earlier, dr macccne's idea was to place an antenna around 550 au from the sun, to receive signals from celestial bodies, or to transmit signals that use the sun as an amplifier. If we're going to launch a spaceship to the nearest star to the sun, it's probably not much to keep the ship in touch with us. In orbit with a 550-AU radius, the period is about 12,000 years, and it is possible for a satellite or antenna in that orbit to move 10 cents a year, aiming in one direction in one year.

  快十年过去了,我对Maccone博士的报告仍然印象深刻。当时的报告听起来就像听科幻故事,但Maccone博士告诉我们,这些想法你应该写下来,提交给某些机构,批不批,管他的,反正这些想法迟早会实现的。如果不写下来的话,这些想法就无法保留下来。

Almost a decade on, I'm still impressed with Dr. Maccone's report. The report at the time sounded like science fiction, but dr. maccone told us that you should write these ideas down, submit them to some agencies, approve them, and leave them to him, but sooner or later these ideas will come true. These ideas cannot be preserved unless they are written down.

  钱磊:国家天文台副研究员。2009年在北京大学天文学系获博士学位。2009年至今在国家天文台FAST工程工作。目前负责FAST谱线数据处理工作。翻译过专著《黑洞吸积盘》以及若干科普文章。

Qian Lei: Associate Research Fellow, National Observatory. Doctorate in 2009 in the Department of Astronomy, Peking University. Worked in the National Observatory FAST project since 2009. currently responsible for fast line data processing. Translated monograph \"black hole accretion disk\" and several popular science articles.


相关热词搜索:

上一篇:安倍举行新年记者会阐述内政外交见解安倍内政
下一篇:没有了

分享到: