科学太阳

本-今年国家天文会议中曾有多次太阳物理讨论, 所以我和伦敦大学学院的Lucie Green见了面, 以探寻最接近恒星的有趣之处

Lucie- 研究太阳有许多有趣的方面。 一方面, 本地恒星对地球产生极大影响, 我们有兴趣研究它究竟如何影响我们。另一方面, 天体物体本身很有意思, 在许多情况下,当我们研究太阳时, 我们实际理解后应用到天体物理的其他领域

本-那我们想从中学习的东西是什么

Lucie -   One of the things that we're most interested in is understanding how the magnetic field of the sun changes.  So, the earth has a very strong magnetic field but the sun has a much stronger and much more interesting magnetic field, and that in fact, it governs much of the activity that happens in the sun.  For example, the work that I'm interested in is looking at how the magnetic field in the atmosphere of the sun evolves and how it leads to big explosions that we call solar flares and eruptions of magnetic field which we called coronal mass ejections.

本-研究最接近恒星能告诉我们什么其他恒星?

Lucie -   We do think it's fairly typical.  But actually, when you think about other stars, it could be that our sun is fairly boring.  The sun is fairly small really when you compare it to other stars and the activity which happens, these explosions and eruptions, even though it's really interesting to solar scientists and people on earth, it kind of pales in comparison to maybe explosions that happen on other stars.  But it still is a good benchmark because we can study the sun in detail, we can resolve the surface.  We have lots and lots of light of all different wavelengths to play with, and we can learn a lot.  One interesting piece of research that has happened recently has taken a model of coronal mass ejections, so these eruptions of magnetic field from the sun's atmosphere and has applied it to jets which are seen coming from the accretion discs of black holes, and that's a really nice transfer of understanding.  So we can look at the coronal mass ejections and we can look at the eruption, we can think about the configuration of the magnetic fields for example and then see if those models match with the observations of black holes, and in this case, they did.

本-如何实际学习?我们需要什么样的工具

Lucie -   We use a lot of tools when it comes to studying the sun.  We can look at maps of the magnetic field at the solar surface and that's very, very important.  And we can get some idea about the three-dimensional field very low down in the sun's atmosphere.  But at the moment, we're not able to measure the magnetic field high up in the sun's atmosphere, and that's partly due to the fact that the gases in the sun's atmosphere are incredibly hot.  So they smear out the signature of the magnetic field.  But actually, a lot of the interesting stuff happens in the magnetic field high up in the atmosphere.  So that's exactly where we want to get the information.  So, in the absence of having a direct measurement of the magnetic field, what we can do is try and infer what's happening and we can do that by taking observations of the sun and x-ray radiation and also, extreme ultraviolet radiation.  And the emission of these wavelengths actually traces out the shapes of the magnetic fields and gives us some sense of what's happening.

Ben-Ben回溯到日志质量反射这些巨大的素材对地球和卫星技术有相当大影响,但实际上是什么原因呢?

Lucie -   Well that's one of the questions I'm working on as a researcher and I think it's one of the most important questions in solar physics.  So, what we're looking at is understanding how the magnetic field evolves.  It all comes down to the magnetic field.  The energy which is required to power these events must come from energy stored in the magnetic field.  So by looking at the shapes, the configurations of the magnetic field, we can start to understand how much energy is stored, and we can also start to understand what causes the magnetic field to suddenly erupt in the first place.  It must lose its equilibrium.  So, the structure exists in the solar atmosphere on the time scale of maybe hours, days.  We're not exactly sure, but it does exist and it's stable, and it's happening.  And then something happens to cause it to erupt up and escape the huge gravitational pull of the sun and that's the moment that we're interested in understanding.

本-你下一站是什么

Lucie -   The next stage is to continue working with Hinode space craft which is a Japanese mission on which we have a UK led telescope.  And what we're going to do is use a very recently discovered signature of a magnetic configuration that we call a flux rope.  A flux rope is a bundle of magnetic field lines which is very good at storing energy in the solar atmosphere.  And using the Hinode space craft, we can understand where these flux ropes are forming and we can look at them up until the point of eruption.  So the plan is to gather a lot of case studies and put the information together to find out at what point this flux rope becomes unstable and erupts as a coronal mass ejection.