by Salman Hameed
If you have followed the blog regularly, you may have seen numerous posts about the flourishing amateur astronomy scene in Pakistan. One of the key figures in this regard is Umair Asim of Lahore Astronomical Society (LAST). For the last year or so we had been in conversation about the possibility of an astronomy podcast in Urdu for individuals who are interested in exploring astronomy topics in more detail. Finally we have launched our Urdu podcast titled "Hamari Kainaat" (Our Universe). We are planning to have an episode every 2 weeks. Here is the first episode on extrasolar planets. Enjoy!
If you have followed the blog regularly, you may have seen numerous posts about the flourishing amateur astronomy scene in Pakistan. One of the key figures in this regard is Umair Asim of Lahore Astronomical Society (LAST). For the last year or so we had been in conversation about the possibility of an astronomy podcast in Urdu for individuals who are interested in exploring astronomy topics in more detail. Finally we have launched our Urdu podcast titled "Hamari Kainaat" (Our Universe). We are planning to have an episode every 2 weeks. Here is the first episode on extrasolar planets. Enjoy!
GREAT! I have a few questions!
ReplyDeleteQ1: You mentioned that the size of the planet (in the eclipse method) can be determined by the dip in brightness caused by the planet as it passes the disc of the star. But how do you factor in things like a big planet orbiting a very large star and a small planet orbiting a smaller star? I mean, shouldnt we get a false reading if the planet itself is very big but causes a small dip in the graph because the star that it transits is itself a very big star and the brightness variation is very small?
Q2: if the plane of an alien star system is inclined to our line of sight, how do we rule out the chance of multiple planets passing in front of the stellar disk at the same time , giving us an illusion of one big planet ?
Q3: What roles do 'sunspots' on these alien stars play in terms of a drop in brightness (when looking for exoplanets ) ?
Great questions, Roshaan:
ReplyDelete1) Astronomers are usually sure about the sizes of regular stars. For example, there are relations between the temperature and radii of stars that are burning hydrogen into helium in the core (these stars are called "Main Sequence stars" and our Sun is one such star). So sun like stars (G-type) will have roughly similar sizes and cooler (M-type) stars will be smaller.
2) The likelihood of this happening is very very small. Even if it does happen, the next orbit will be different, and the nearer planet will be moving faster than the farther planet - thus showing us multiple planets. And confirmation of planets come after at least 2 passes.
3) It is not the sunspots directly, but rather the general variability of stars. Planetary motions are stable and so irregular phenomenon like the sunspots are relatively easy to rule out. However, bigger problem are variable stars that do vary in brightness periodically. Indeed some ( a few) extrasolar planets have been redacted because of some of these issues.
I am a Newbie with lack of knowledge in Astronomy. I understand things at the very basic level but I can picture that how incomprehensible the size of universe is. I do like to hear things on this matter. can you pls. tell me where to start and if I can join an amateur society ?
ReplyDeleteKeep up the good work!
Ali - there are fantastic amateur astronomy groups in Karachi, Lahore and I think in Islamabad as well. For Lahore, you should look at LAST and for Karachi, KaAS. Good luck.
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