Statistics: Posted by Xoran — 30 Mar 2017 08:14

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Statistics: Posted by Hornblower — 30 Mar 2017 03:45

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Statistics: Posted by Gnargenox — 29 Mar 2017 21:32

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The equation for the radial velocity of a star with n planets, with K_i being the i-th planet's RV semi-amplitude (which you can use to get its mass), ε_i is the i-th planet's eccentric anomaly (the location of the planet around its orbit after you take eccentricity into account), ω_i is the i-th planet's longitude of periapsis, and γ is just some offset between the observer and the star.

[math]

Upsilon Andromedae, which has both a hot Jupiter and a planet at ~1200 days, was hard to see anything because the hot Jupiter's signal flooded the screen with rapid short-wavelength chaos. Eventually the program will do Newtonian fitting for characterizing planet-planet interactions, transit modelling and the Rossiter-McLaughin effect. Obviously needs to add ability to analyze bisector widths and full-width-at-half-maximums for the spectral lines for a sanity-check to make sure the signals you detect aren't the star trolling you. He also has to figure out detrending and noise management, too. He was completely unable to recover the planet around Lalande 21185 reported last month.

In the right panel he was folding at various orbital periods trying to see a coherent signal by eye (since there isn't any periodgram capability yet). At the bottom you see a few bad data points were pruned because they were quite different from the rest of the data set.

Here is 51 Peg b. Obviously there are ways to improve how data is presented. Multi-planet systems where orbital periods vary quite a bit is alot harder. Imagine if 51 Peg had a second detectable planet (or take the real example of WASP-47). The first panel would be a freaking mess, lol. Still needs to be able to fit to residuals or subtract signals.

I only mention this because he might release a beta soon and might have a link where you can download and use it to do calculations.

Statistics: Posted by Gnargenox — 29 Mar 2017 21:27

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since all you have is information from transit method, the best you can do for determining the planet's mass is constrain it by the Mass-Radius relation for solid planets. If the planet is 2.6 Earth Radii, it's pretty implausible to be a solid iron planet (it would have to be hundreds of Earth masses), or even a silicate planet (would have to be at least 20 Earth masses). More likely it is a water planet.

We can do better for the orbital distance. To do it, determine the mass of the star from available data, and then apply Kepler's Third Law.

Based on the KIC catalog data, the star has an effective temperature of 4741K, plus or minus 200K, and a radius of 0.831 solar units. That would make it a K-class star. We can find the star's luminosity in solar units by

which comes to 0.315 +/- 0.05 Suns. Then by the Mass-Luminosity relationship,

we find the star's mass to be 0.749 +/- 0.032 Suns. Apply this to Kepler's Third Law:

where G is the gravitational constant, M is the star's mass, and T is the planet's orbital period,

Now that we have the planet's distance and the star's luminosity, a fun calculation is to find the planet's surface temperature (assuming the planet is a blackbody -- albedo and/or greenhouse effect can of course change it)

where A

This tells us that an earth-like planet in that orbit would have a surface temperature of about 400K. Pretty warm!

Statistics: Posted by Watsisname — 29 Mar 2017 21:20

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Statistics: Posted by Hornblower — 29 Mar 2017 19:12

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Here's one of the transits of the possible exoplanet:

No but seriously, can anyone calculate some stuff?

Statistics: Posted by Hornblower — 29 Mar 2017 19:11

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I think I found an exoplanet! I need some help with calculating the orbital radius and mass of the planet. Here's the data:

Size: 2.6 Earth Radii

Orbital Period: 71.22 days

Star: KIC 7801296

I realize it might not be possible to calculate the mass, but atleast a range of values for the orbital radius would be great! Thanks in advance,

(Also, let me know if you need to know anything else about the planet, discovered by transit)

How did you manage that? Backyard telescope or something bigger / more sophisticated?

Statistics: Posted by Quontex — 29 Mar 2017 19:04

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Statistics: Posted by Spacer — 29 Mar 2017 12:43

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Orbital Period: 71.22 days

Star: KIC 7801296

I realize it might not be possible to calculate the mass, but atleast a range of values for the orbital radius would be great! Thanks in advance,

(Also, let me know if you need to know anything else about the planet, discovered by transit)

Statistics: Posted by Hornblower — 29 Mar 2017 06:27

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I agree, very interesting pictures, and the double cluster is awesome.

Thank you!

Watsisname wrote:

Bambusman, oh, ok! You're doing great. Light pollution and lack of a mount are indeed a bummer, but it's amazing what you can do with what you have!

Thank you! At least i can watch the sky while taking the images.

Statistics: Posted by Bambusman — 29 Mar 2017 03:01

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Statistics: Posted by TheRedstoneHive — 29 Mar 2017 00:11

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Statistics: Posted by Watsisname — 28 Mar 2017 21:45

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