High-precision photometry by telescope defocusing – VII. The ultrashort period planet WASP-103

TY - JOUR

T1 - High-precision photometry by telescope defocusing – VII. The ultrashort period planet WASP-103

AU - Southworth, John

AU - Mancini, L.

AU - Ciceri, S.

AU - Budaj, J.

AU - Dominik, M.

AU - Jaimes, R. Figuera

AU - Haugbølle, Troels

AU - Jørgensen, Uffe Gråe

AU - Popovas, Andrius

AU - Rabus, M.

AU - Rahvar, S.

AU - Essen, C. von

AU - Schmidt, R. W.

AU - Wertz, O.

AU - Alsubai, K. A.

AU - Bozza, V.

AU - Bramich, D. M.

AU - Novati, S. Calchi

AU - D'Ago, G.

AU - Hinse, T. C.

AU - Henning, T.

AU - Hundertmark, Markus

AU - Juncher, Diana

AU - Korhonen, Heidi Helena

AU - Skottfelt, Jesper Mirsa

AU - Snodgrass, C.

AU - Starkey, D.

AU - Surdej, J.

PY - 2015/2/11

Y1 - 2015/2/11

N2 - We present 17 transit light curves of the ultrashort period planetary system WASP-103, a strong candidate for the detection of tidally-induced orbital decay. We use these to establish a high-precision reference epoch for transit timing studies. The time of the reference transit mid-point is now measured to an accuracy of 4.8 s, versus 67.4 s in the discovery paper, aiding future searches for orbital decay. With the help of published spectroscopic measurements and theoretical stellar models, we determine the physical properties of the system to high precision and present a detailed error budget for these calculations. The planet has a Roche lobe filling factor of 0.58, leading to a significant asphericity; we correct its measured mass and mean density for this phenomenon. A high-resolution Lucky Imaging observation shows no evidence for faint stars close enough to contaminate the point spread function of WASP-103. Our data were obtained in the Bessell RI and the SDSS griz passbands and yield a larger planet radius at bluer optical wavelengths, to a confidence level of 7.3σ. Interpreting this as an effect of Rayleigh scattering in the planetary atmosphere leads to a measurement of the planetary mass which is too small by a factor of 5, implying that Rayleigh scattering is not the main cause of the variation of radius with wavelength.

AB - We present 17 transit light curves of the ultrashort period planetary system WASP-103, a strong candidate for the detection of tidally-induced orbital decay. We use these to establish a high-precision reference epoch for transit timing studies. The time of the reference transit mid-point is now measured to an accuracy of 4.8 s, versus 67.4 s in the discovery paper, aiding future searches for orbital decay. With the help of published spectroscopic measurements and theoretical stellar models, we determine the physical properties of the system to high precision and present a detailed error budget for these calculations. The planet has a Roche lobe filling factor of 0.58, leading to a significant asphericity; we correct its measured mass and mean density for this phenomenon. A high-resolution Lucky Imaging observation shows no evidence for faint stars close enough to contaminate the point spread function of WASP-103. Our data were obtained in the Bessell RI and the SDSS griz passbands and yield a larger planet radius at bluer optical wavelengths, to a confidence level of 7.3σ. Interpreting this as an effect of Rayleigh scattering in the planetary atmosphere leads to a measurement of the planetary mass which is too small by a factor of 5, implying that Rayleigh scattering is not the main cause of the variation of radius with wavelength.

KW - astro-ph.EP

KW - astro-ph.SR

U2 - 10.1093/mnras/stu2394

DO - 10.1093/mnras/stu2394

M3 - Journal article

SN - 0035-8711

VL - 447

SP - 711

EP - 721

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

IS - 1

ER -