* Astronomy

High-precision Transit Photometry of OGLE-TR-10
Authors: Matthew J. Holman, Joshua N. Winn, K.Z. Stanek, Guillermo Torres, Dimitar D. Sasselov, R. Lynne Allen, Wesley Fraser

Researchers present B and I photometry of OGLE-TR-10 during transits of its giant planet.
From their observations, they estimate the radius of the planet to be 1.16 +/- 0.05 times the radius of Jupiter, assuming a stellar mass of 1.02 solar masses.
This is smaller than previous estimates that were based on lower-precision data, and hence the planet is not as anomalous as was once believed.
They provide updated determinations of all the system parameters based on a joint analysis of their photometry and the star's radial velocity variations.

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“Apart from Mercury and Venus, we know of 7 planets that transit their parent stars as viewed from Earth. One of these extrasolar planets was discovered by observing radial velocity variations of the parent star and then searching for the photometric signal of transits.
In the other cases, the photometric signals were discovered first, and then confirmed as planetary transits through radial velocity studies. Regardless of the order of events, the combination of photometry and dynamical measurements allows the mass and radius of the planet (and hence its mean density) to be determined.
This has given us the first clues about the interior structures of these other worlds. Most of the transiting extrasolar planets have mean densities between 0.6 and 1.2 g cm.3, suggesting they are not too different from the well-studied gas giants Saturn (0.7 g cm.3) and Jupiter (1.3 g cm.3). However, the first transiting planet that was discovered, HD 209458b, has a much smaller density of 0.33 g cm.3 .
This anomaly has led to speculation about novel sources of internal heat, such as eccentricity damping, insolation-driven weather patterns, and obliquity tides (Winn & Holman 2005). Thus the recent discovery of the transiting planet OGLE-TR-10b, with the anomalously small density of 0.38±0.10 g cm.3, was greeted with considerable interest.
Here we present higher-precision photometry of transits of OGLE-TR-10”

System parameters of OGLE-TR-10

MP [MJup]                      0.54                    
R. [R⊙]                        1.18                  
RP [RJup]                      1.16                     
P [days]                    3.101269                    
Tc- 2,452,761 [HJD]         0.80769             
Incl. [deg]                    86.46           
HIRES [m s.1]                  -6250                           
UVES - HIRES [m s.1]           -215               
FLAMES - HIRES [m s.1]            3