Co-discovery of the transiting exoplanet XO-3b

In May 2006, the XO consortium announced its first discovery of a transiting exoplanet, named XO-1b. The discovery attracted a lot of attention, a/o due to the important role played by 4 amateur astronomers - including myself - in the months preceding the discovery announcement. The full story is here. The XO Project begins its search with a telescope located on Haleakala summit operated by the Institute for Astronomy of the University of Hawaii. The telescope is created from two commercially available 200-millimeter telephoto camera lenses. Using the Haleakala telescope, XO's professional team first identifies candidate stars that dim ever so slightly from time to time. XO's amateur astronomers (the "XO Extended Team") observe these candidates over time and look for further evidence that the dimming is due to a transiting planet. Once enough evidence is in place, the professional team uses large telescopes -- the 2.7-meter Harlan J. Smith Telescope and the 11-meter Hobby-Ebberly Telescope, both at the University of Texas McDonald Observatory in West Texas -- to confirm the presence of a transiting planet.

Early May 2007, the second discovery by XO was announced : XO-2b. Merely a few weeks later, we already announced our third discovery : XO-3b. Again, the XO Extended Team had been monitoring the object intensively in the months before the discovery was made public. At that time, the object was given the codename 060p59.0420, and below are some of my observations of this object, going back to October 2006 !

Unfiltered observations of XO-3, obtained at CBA Belgium Observatory between October 2006 and October 2007, 
using a 0.35-m f/6.3 telescope and ST-7XME CCD camera.
Error bars depict the standard deviation.

XO-3b properties

XO-3b's host is a 10-th mag F dwarf star at R.A. = 04h21m53s and Decl.= +5749.0' (J2000.0). The exoplanet itself is more than 12 times as massive as Jupiter and orbits its host star once every 3.2 days, in a tight, elongated orbit. XO-3b is by far the most massive "hot Jupiter" found so far, and on the borderline of being a brown dwarf. It's the largest and most massive planet yet found in such a close orbit, and given the proximity of the orbit to the star, it's a surprise to find that the orbit is not circular but significantly elliptical. The debate on the classification of XO-3b is ongoing at the moment of this writing (June 2007).





Copyright © 2006 - Tonny Vanmunster.