High-precision photometry by telescope defocusing - IV. Confirmation of the huge radius of WASP-17 b

John Southworth; T. C. Hinse; M. Dominik; X.-S Fang; Kennet Bomann West Harpsøe; Uffe Gråe Jørgensen; E. Kerins; C. Liebig; M. Mancini; Jesper Mirsa Skottfelt; D. R. Anderson; B. Smalley; J. Tregloan-Reed; O. Wertz; K. A. Alsubai; V. Bozza; S. Calchi Novati; S. Dreizler; S.-H. Gu; M. Hundertmark; J. Jessen-Hansen; N. Kains; H. Kjeldsen; M. N. Lund; M. Lundkvist; M. Mathiasen; M. T. Penny; S. Rahvar; D. Ricci; G. Scarpetta; C. Snodgrass; J. Surdej

doi:10.1111/j.1365-2966.2012.21781.x

High-precision photometry by telescope defocusing - IV. Confirmation of the huge radius of WASP-17 b

John Southworth, T. C. Hinse, M. Dominik, X.-S Fang, Kennet Bomann West Harpsøe, Uffe Gråe Jørgensen, E. Kerins, C. Liebig, M. Mancini, Jesper Mirsa Skottfelt, D. R. Anderson, B. Smalley, J. Tregloan-Reed, O. Wertz, K. A. Alsubai, V. Bozza, S. Calchi Novati, S. Dreizler, S.-H. Gu, M. HundertmarkJ. Jessen-Hansen, N. Kains, H. Kjeldsen, M. N. Lund, M. Lundkvist, M. Mathiasen, M. T. Penny, S. Rahvar, D. Ricci, G. Scarpetta, C. Snodgrass, J. Surdej

Astrophysics and Planetary Science

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Abstract

We present photometric observations of four transits in the WASP-17 planetary system, obtained using telescope defocusing techniques and with scatters reaching 0.5mmag per point. Our revised orbital period is 4.0 ± 0.6s longer than previous measurements, a difference of 6.6σ, and does not support the published detections of orbital eccentricity in this system. We model the light curves using the jktebop code and calculate the physical properties of the system by recourse to five sets of theoretical stellar model predictions. The resulting planetary radius, R _b = 1.932 ± 0.052 ± 0.010R _Jup (statistical and systematic errors, respectively), provides confirmation that WASP-17b is the largest planet currently known. All 14 planets with radii measured to be greater than 1.6R _Jup are found around comparatively hot (T _eff > 5900K) and massive (M _A > 1.15M _⊙) stars. Chromospheric activity indicators are available for eight of these stars, and all imply a low activity level. The planets have small or zero orbital eccentricities, so tidal effects struggle to explain their large radii. The observed dearth of large planets around small stars may be natural but could also be due to observational biases against deep transits, if these are mistakenly labelled as false positives and so not followed up.

Original language	English
Journal	Monthly Notices of the Royal Astronomical Society
Volume	426
Issue number	2
Pages (from-to)	1338-1348
Number of pages	10
ISSN	0035-8711
DOIs	https://doi.org/10.1111/j.1365-2966.2012.21781.x
Publication status	Published - 21 Oct 2012

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Southworth, J., Hinse, T. C., Dominik, M., Fang, X. -S., Harpsøe, K. B. W., Jørgensen, U. G., Kerins, E., Liebig, C., Mancini, M., Skottfelt, J. M., Anderson, D. R., Smalley, B., Tregloan-Reed, J., Wertz, O., Alsubai, K. A., Bozza, V., Novati, S. C., Dreizler, S., Gu, S-H., ... Surdej, J. (2012). High-precision photometry by telescope defocusing - IV. Confirmation of the huge radius of WASP-17 b. Monthly Notices of the Royal Astronomical Society, 426(2), 1338-1348. https://doi.org/10.1111/j.1365-2966.2012.21781.x

Southworth, J, Hinse, TC, Dominik, M, Fang, X-S, Harpsøe, KBW, Jørgensen, UG, Kerins, E, Liebig, C, Mancini, M, Skottfelt, JM, Anderson, DR, Smalley, B, Tregloan-Reed, J, Wertz, O, Alsubai, KA, Bozza, V, Novati, SC, Dreizler, S, Gu, S-H, Hundertmark, M, Jessen-Hansen, J, Kains, N, Kjeldsen, H, Lund, MN, Lundkvist, M, Mathiasen, M, Penny, MT, Rahvar, S, Ricci, D, Scarpetta, G, Snodgrass, C & Surdej, J 2012, 'High-precision photometry by telescope defocusing - IV. Confirmation of the huge radius of WASP-17 b', Monthly Notices of the Royal Astronomical Society, vol. 426, no. 2, pp. 1338-1348. https://doi.org/10.1111/j.1365-2966.2012.21781.x

@article{8cdf670fbad0406c8167695b03e60557,

title = "High-precision photometry by telescope defocusing - IV. Confirmation of the huge radius of WASP-17 b",

abstract = "We present photometric observations of four transits in the WASP-17 planetary system, obtained using telescope defocusing techniques and with scatters reaching 0.5mmag per point. Our revised orbital period is 4.0 ± 0.6s longer than previous measurements, a difference of 6.6σ, and does not support the published detections of orbital eccentricity in this system. We model the light curves using the jktebop code and calculate the physical properties of the system by recourse to five sets of theoretical stellar model predictions. The resulting planetary radius, R b = 1.932 ± 0.052 ± 0.010R Jup (statistical and systematic errors, respectively), provides confirmation that WASP-17b is the largest planet currently known. All 14 planets with radii measured to be greater than 1.6R Jup are found around comparatively hot (T eff > 5900K) and massive (M A > 1.15M ⊙) stars. Chromospheric activity indicators are available for eight of these stars, and all imply a low activity level. The planets have small or zero orbital eccentricities, so tidal effects struggle to explain their large radii. The observed dearth of large planets around small stars may be natural but could also be due to observational biases against deep transits, if these are mistakenly labelled as false positives and so not followed up.",

author = "John Southworth and Hinse, {T. C.} and M. Dominik and X.-S Fang and Harps{\o}e, {Kennet Bomann West} and J{\o}rgensen, {Uffe Gr{\aa}e} and E. Kerins and C. Liebig and M. Mancini and Skottfelt, {Jesper Mirsa} and Anderson, {D. R.} and B. Smalley and J. Tregloan-Reed and O. Wertz and Alsubai, {K. A.} and V. Bozza and Novati, {S. Calchi} and S. Dreizler and S.-H. Gu and M. Hundertmark and J. Jessen-Hansen and N. Kains and H. Kjeldsen and Lund, {M. N.} and M. Lundkvist and M. Mathiasen and Penny, {M. T.} and S. Rahvar and D. Ricci and G. Scarpetta and C. Snodgrass and J. Surdej",

year = "2012",

month = oct,

day = "21",

doi = "10.1111/j.1365-2966.2012.21781.x",

language = "English",

volume = "426",

pages = "1338--1348",

journal = "Royal Astronomical Society. Monthly Notices",

issn = "0035-8711",

publisher = "Oxford University Press",

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TY - JOUR

T1 - High-precision photometry by telescope defocusing - IV. Confirmation of the huge radius of WASP-17 b

AU - Southworth, John

AU - Hinse, T. C.

AU - Dominik, M.

AU - Fang, X.-S

AU - Harpsøe, Kennet Bomann West

AU - Jørgensen, Uffe Gråe

AU - Kerins, E.

AU - Liebig, C.

AU - Mancini, M.

AU - Skottfelt, Jesper Mirsa

AU - Anderson, D. R.

AU - Smalley, B.

AU - Tregloan-Reed, J.

AU - Wertz, O.

AU - Alsubai, K. A.

AU - Bozza, V.

AU - Novati, S. Calchi

AU - Dreizler, S.

AU - Gu, S.-H.

AU - Hundertmark, M.

AU - Jessen-Hansen, J.

AU - Kains, N.

AU - Kjeldsen, H.

AU - Lund, M. N.

AU - Lundkvist, M.

AU - Mathiasen, M.

AU - Penny, M. T.

AU - Rahvar, S.

AU - Ricci, D.

AU - Scarpetta, G.

AU - Snodgrass, C.

AU - Surdej, J.

PY - 2012/10/21

Y1 - 2012/10/21

N2 - We present photometric observations of four transits in the WASP-17 planetary system, obtained using telescope defocusing techniques and with scatters reaching 0.5mmag per point. Our revised orbital period is 4.0 ± 0.6s longer than previous measurements, a difference of 6.6σ, and does not support the published detections of orbital eccentricity in this system. We model the light curves using the jktebop code and calculate the physical properties of the system by recourse to five sets of theoretical stellar model predictions. The resulting planetary radius, R b = 1.932 ± 0.052 ± 0.010R Jup (statistical and systematic errors, respectively), provides confirmation that WASP-17b is the largest planet currently known. All 14 planets with radii measured to be greater than 1.6R Jup are found around comparatively hot (T eff > 5900K) and massive (M A > 1.15M ⊙) stars. Chromospheric activity indicators are available for eight of these stars, and all imply a low activity level. The planets have small or zero orbital eccentricities, so tidal effects struggle to explain their large radii. The observed dearth of large planets around small stars may be natural but could also be due to observational biases against deep transits, if these are mistakenly labelled as false positives and so not followed up.

AB - We present photometric observations of four transits in the WASP-17 planetary system, obtained using telescope defocusing techniques and with scatters reaching 0.5mmag per point. Our revised orbital period is 4.0 ± 0.6s longer than previous measurements, a difference of 6.6σ, and does not support the published detections of orbital eccentricity in this system. We model the light curves using the jktebop code and calculate the physical properties of the system by recourse to five sets of theoretical stellar model predictions. The resulting planetary radius, R b = 1.932 ± 0.052 ± 0.010R Jup (statistical and systematic errors, respectively), provides confirmation that WASP-17b is the largest planet currently known. All 14 planets with radii measured to be greater than 1.6R Jup are found around comparatively hot (T eff > 5900K) and massive (M A > 1.15M ⊙) stars. Chromospheric activity indicators are available for eight of these stars, and all imply a low activity level. The planets have small or zero orbital eccentricities, so tidal effects struggle to explain their large radii. The observed dearth of large planets around small stars may be natural but could also be due to observational biases against deep transits, if these are mistakenly labelled as false positives and so not followed up.

U2 - 10.1111/j.1365-2966.2012.21781.x

DO - 10.1111/j.1365-2966.2012.21781.x

M3 - Journal article

SN - 0035-8711

VL - 426

SP - 1338

EP - 1348

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

IS - 2

ER -

High-precision photometry by telescope defocusing - IV. Confirmation of the huge radius of WASP-17 b

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