HW 4 Question 2

The planet orbiting VB 10 was a very interesting case given the circumstances of what it is and the star that it orbits. VB 10 is an ultracool M-Dwarf star close to the lower mass limit of what we consider a star to be The planet orbiting VB10 is roughly 6.4 Jupiter masses with an orbital period of 0.744 years (271.56 days) and was detected using the radial velocity method.But detecting a solar system in this way is very strange indeed since the radial velocity method is predominately used on what we can see visably, but the star is an ultracool M-Dwarf which typically makes stars like this too dim to see properly. To measure radial velocity from the near Infrared spectrum is the most optimal means of detecting these systems, but using the CRIRES on an ammonia gas cell, the odds were found to be a bit too out of the ordinary. Currently this technique is incredibly outshined (excuse the pun) by systems detected in visible light, but the problem there lies within the incredibly large false alarm probability. There is a 2 × 10-8 probability of detecting solar systems that fit within the parallax and proper motion model within visual light whereas the margin for false alarm probability for a period to be randomly generated was 3 × 10-5 . With this being the case, The CRIRES system ran the statistical data given by Pravado and Shaklan and concluded that, since the system rules out planets with masses greater than 3 Jupiter masses, the inclination and orbital period of the rumored planet only come within 5sigma of confidence which is not close enough to the acceptable 2sigma to be taken as factual evidence. However, it does prove that the detection of ultracool and dwarf type stars should be scanned more often with the ammonia cell radial velocity method in order to detect orbiting planets in the future.



Links to the articles:
http://adsabs.harvard.edu/abs/2009ApJ...700..623P
http://adsabs.harvard.edu/abs/2010ApJ...711L..19B

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