How Can We Study Exoplanets Using the Doppler Effect?

[Brandon BW]

Several friends and I have a great yet unexplored interest in Astrophysics, and interesting Math not taught in the typical high school course. We have decided on forming a discussion based "club" (we will read/do research in between discussions) to help us learn more deeply and efficiently. I am a senior in High School, and would love to accomplish something by the summer because it may be difficult to continue discussing the concepts with the same people afterwards. We would like to try and tackle some relativity, but our math background in limited (I'll be starting multi-variable calculus next semester, and there are a few that haven't taken calculus yet). I was wondering if anyone has any suggestions or directions for study that may be satisfying, yet plausible. We could find help for some difficult concepts, but we can't have a Physics professor with us all the time.

 

[musicheck]

http://www.gravityfromthegroundup.org/ might be an interesting book for you guys to work through. It uses no calc and covers quite a few physically interesting topics, ranging through various parts of classical mechanics to a bit of general relativity, all with an emphasis on astro and cosmology.

 

[Kurdt]

The mathematics behind special relativity isn't too difficult for high school students if you did want to have a look at it. General Relativity in comparison is a lot harder. Exoplanets have been quite big for a while. You could read up on the detection methods and the planned missions to detect them. If you wanted to explore the maths behind the detection methods you shouldn't be too challenged.

Beyond that just read whatever takes your interest.

 

[marcus]

Exoplanets have been quite big for a while. You could read up on the detection methods and the planned missions to detect them. If you wanted to explore the maths behind the detection methods you shouldn't be too challenged.
...

That strikes me as an extremely good suggestion.

Most of the exoplanets that have been detected so far have been discovered by observing wobble Doppler-effect.
How can an astronomer estimate the mass of a planet, and its distance from the star, without seeing the planet itself?

to understand how that works, you learn a bunch of things that are really basic to astrophysics (more basic, actually more used, I would say, than special relativity.) The math is simple but elegant.

Geoff Marcy is a hero of mine. Lick observatory where he and Paul Butler discovered some of the first exoplanets is near here. I went to visit it. Met Marcy and heard him talk back in the 1990s soon after their first findings were announced.

The techniques for measuring the Doppler shift due to a few tens of meters per second motion of a star, towards and away, were at that time very ingenious. Marcy would put an iodine lightbulb up in the telescope so that they could compare the star's spectral lines with the known spectral lines of iodine. They had to be able to see shifts in the lines with unprecedented precision.

The whole exoplanet thing is historical and fascinating. Kurdt mentioned orbital instruments that will be launched to carry on with the planet search. I think it would be an extremely good thing to study in high school----many aspects---accessible---several branches of science involved. Plenty of stuff available online too.