User talk:MD:astronomer

So how does that work? The pre-print article uses the term "sepration" in the abstract - Vedexent 17:32, 16 March 2006 (UTC)[reply]

It is nowhere stated that "separation" should imply a projection, the caption to Fig. 2 states explicitly that it is not a projection. The parameter d is indeed the projected angular separation in units of the angular Einstein radius, from which the projected separation follows with the adopted Galaxy model on a stochasic basis. Finally, a deprojection has been done with a stochastic distribution of the projection factor assuming a circular orbit.

If a circular orbit is not assumed, what information about the separation is there? I'm asking because it seems quite a few extrasolar planets are in highly elliptical orbits, which presumably is a possibility in this system. Chaos syndrome 15:49, 20 March 2006 (UTC)[reply]

If a distribution of the eccentricities is assumed that fits the distribution for the observed systems, there is a broader distribution for the orbital semi-major axis and period, with the expectation value for the former being about 10% smaller.

Thanks for the help. Would it be better to put "separation" rather than "orbital radius" in the infobox then, since the eccentricity is not known? The text refers to the quantity d as the "projected planet-star separation" in the third last paragraph, is this something different? Chaos syndrome 12:07, 27 March 2006 (UTC)[reply]

"Separation" can be misunderstood as the distance of the planet and its host star from Earth. "Orbital radius" makes clear that a circular orbit has been assumed. d is the angular separation in units of the angular Einstein radius, i.e. a dimensionless parameter. The planet affects the observed light curve only by means of d and the planet-to-star mass ratio q.