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Orbital Period According to Kepler's Third Law, the orbital period $T$ is defined as $$T=2\pi\sqrt \frac{a^3}{\mu}$$ $T$ is, as said before, the orbital period (i.e. the time for an object - in this case, the planet - to complete an orbit around the massive, central object - in this case, the star) measured in seconds. $a$ is the object's semi-major axis (...

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The formula for orbital period is given on Wikipedia: $$T=2\pi \sqrt\frac{a^3}\mu$$ where: $T$ is the orbital period in seconds $a$ is the orbit's semi-major axis in meters $\mu = GM$ is the standard gravitational parameter $G$ is the gravitational constant $M$ is the mass of the more massive body in kilograms So $T = 2 \pi \sqrt \frac { (172 \cdot 10^9) ^... 2 The introduction of the Wyrzykowski & Mandel paper gives the following information about estimating the lens mass. In order to obtain the mass of the lens (Gould 2000a), it is necessary to measure both the angular Einstein radius of the lens ($\theta_\mathrm{E}$) and the microlensing parallax ($\pi_\mathrm{E}$)$\$M = \frac{\theta_\mathrm{E}}{\kappa \pi_\...

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There is basically an upper limit to the mass of a star because their luminosity is so great that the radiation pressure prevents the accretion of further mass. However, the upper limit depends on the composition of the accreting material. This is because the effect of the radiation depends on the opacity of the material - stuff that is more metal-rich is ...

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