[en] We report the discovery by the WASP transit survey of a giant planet in a close orbit (0.0295 ± 0.0009 AU) around a moderately bright (V = 11.6, K = 10) G9 dwarf (0.89 ± 0.08 M[SUB]&sun;[/SUB], 0.84 ± 0.03 R[SUB]&sun;[/SUB]) in the Southern constellation Eridanus. Thanks to high-precision follow-up photometry and spectroscopy obtained by the telescopes TRAPPIST and Euler, the mass and size of this planet, WASP-50 b, are well constrained to 1.47 ± 0.09 M[SUB]Jup[/SUB] and 1.15 ± 0.05 R[SUB]Jup[/SUB], respectively. The transit ephemeris is 2 455 558.6120 (±0.0002) + N × 1.955096 (±0.000005) HJD[SUB]UTC[/SUB]. The size of the planet is consistent with basic models of irradiated giant planets. The chromospheric activity (log R'[SUB]HK = -4.67[/SUB]) and rotational period (P[SUB]rot[/SUB] = 16.3 ± 0.5 days) of the host star suggest an age of 0.8 ± 0.4 Gy that is discrepant with a stellar-evolution estimate based on the measured stellar parameters (ρ[SUB]∗[/SUB] = 1.48 ± 0.10 ρ[SUB]&sun;[/SUB], T[SUB]eff[/SUB] = 5400 ± 100 K, [Fe/H] = -0.12 ± 0.08) which favors an age of 7 ± 3.5 Gy. This discrepancy could be explained by the tidal and magnetic influence of the planet on the star, in good agreement with the observations that stars hosting hot Jupiters tend to show faster rotation and magnetic activity. We measure a stellar inclination of 84[SUB]-31[SUP]+6[/SUP][/SUB] deg, disfavoring a high stellar obliquity. Thanks to its large irradiation and the relatively small size of its host star, WASP-50 b is a good target for occultation spectrophotometry, making it able to constrain the relationship between hot Jupiters' atmospheric thermal profiles and the chromospheric activity of their host stars. The photometric time-series used in this work are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/533/A88">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/533/A88</A>
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Gillon, Michaël ; Université de Liège, Allée du 6 août 17, Sart Tilman, Liège 1, Belgium
Doyle, A. P.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Lendl, M.; Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290, Sauverny, Switzerland
Maxted, P. F. L.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Triaud, A H M J; Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290, Sauverny, Switzerland
Anderson, D. R.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Barros, S. C. C.; Astrophysics Research Centre, School of Mathematics & Physics, Queen's University, University Road, Belfast, BT7 1NN, UK
Bento, J.; Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
Collier-Cameron, A.; School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife, KY16 9SS, UK
Enoch, B.; School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife, KY16 9SS, UK
Faedi, F.; Astrophysics Research Centre, School of Mathematics & Physics, Queen's University, University Road, Belfast, BT7 1NN, UK
Hellier, C.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Jehin, Emmanuel ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Magain, Pierre ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Montalban Iglesias, Josefa ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Pepe, F.; Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290, Sauverny, Switzerland
Pollacco, D.; Astrophysics Research Centre, School of Mathematics & Physics, Queen's University, University Road, Belfast, BT7 1NN, UK
Queloz, D.; Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290, Sauverny, Switzerland
Smalley, B.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Segransan, D.; Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290, Sauverny, Switzerland
Smith, A. M. S.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Southworth, J.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Udry, S.; Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290, Sauverny, Switzerland
West, R. G.; Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK
Wheatley, P. J.; Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
Baranne, A., Queloz, D., Mayor, M., et al. 1996, A&AS, 119, 373
Barnes, S. A. 2007, ApJ, 669, 1167
Borucki, W. J., Koch, D. G., Gautier, T. N., et al. 2011, AAS Meeting, BAAS, 217, 43
Burrows, A., Budaj, J., & Hubeny, I. 2008, ApJ, 678, 1436
Cabrera, J., Bruntt, H., Ollivier, M., et al. 2010, A&A, 522, A110
Chan, T., Ingemyr, M., Winn, J., et al. 2011, AJ, 141, 179
Chang, S.-H., Gu, P.-G., & Bodenheimer, P. H. 2010, ApJ, 708, 1692
Claret, A. 2000, A&A, 363, 1081
Claret, A. 2004, A&A, 428, 1001
Collier Cameron, A., Pollacco, D., Street, R. A., et al. 2006, MNRAS, 373, 799
Collier Cameron, A., Wilson, D. M., West, R. G., et al. 2007, MNRAS, 380, 1230
Correia, A. C. M., & Laskar, J. 2010, Exoplanets, ed. S. Seager (University of Arizona Press), 239
Cox, A. N. 2000, Allen's astrophysical quantities, 4th ed. (Springer)
D'Angelo, G., Durisen, R. H., & Lissauer, J. J. 2010, Exoplanets, ed. S. Seager (University of Arizona Press), 319
Deming, D., Knutson, H., Agol, E., et al. 2011, ApJ, 726, 94
Enoch, B., Collier Cameron, A., Parley, N. R., & Hebb, L. 2010, A&A, 516, A33
Fortney, J. J., Marley, M. S., & Barnes, J. W. 2007, ApJ, 659, 1661
Fortney, J. J., Baraffe, I., & Militzer, B. 2010, Exoplanets, ed. S. Seager (University of Arizona Press), 397
Gelman, A., & Rubin, D. 1992, Stat. Sci., 7, 457
Gillon, M., Smalley, B., Hebb, L., et al. 2009a, A&A, 496, 259
Gillon, M., Demory, B.-O., Triaud, A. H. M. J., et al. 2009b, A&A, 506, 359
Gillon, M., Lanotte, A. A., Barman, T., et al. 2010a, A&A, 511, A3
Gillon, M., Hatzes, A., Csizmadia, Sz., et al. 2010b, A&A, 520, A97
Gillon, M., Jehin, E., Magain, P., et al. 2011, Detection and Dynamics of Transiting Exoplanets, 23-27 August 2010, ed. F. Bouchy, R. F. Diaz, & C. Moutou (Platypus Press), Proc. OHP Colloq.
Gray, D. F. 2008, The observation and analysis of stellar photospheres, 3rd ed. (Cambridge University Press), 507
Hartman, J. D. 2010, ApJ, 717, L138
Hebb, L., Collier-Cameron, A., Loeillet, B., et al. 2009, ApJ, 693, 1920
Holman, M. J., Winn, J. N., Latham, D. W., et al. 2006, ApJ, 652, 1715
Knutson, H. A., Howard, A. W., & Isaacson, H. 2010, ApJ, 720, 1569
Lanza, A. F. 2010, A&A, 712, A77
Lubow, S. H., & Ida, S. 2010, Exoplanets, ed. S. Seager (University of Arizona Press), 347
Mandel, K., & Agol, E. 2002, ApJ, 580, 181
Magain, P. 1984, A&A, 134, 189
Maxted, P. F. L., Anderson, D. R., Collier Cameron, A., et al. 2011, PASP, 123, 547
Pollacco, D. L., Skillen, I., Collier Cameron, A., et al. 2006, PASP, 118, 1407
Press, W. H., Teukolsky, S. A., Vetterling, W. T., & Flannery, B. P. 1882, Numerical Recipes in FORTRAN: The Art of Scientific Computing (Cambridge: Cambridge Univ. Press)
Pont, F. 2009, MNRAS, 396, 1789
Queloz, D., Henry, G. W., Sivan, J. P., et al. 2001, A&A, 379, 279
Scuflaire, R., Théado, S., Montalán, J., et al. 2008, AP&SS, 316, 83
Seager, S. 2010, Exoplanet Atmospheres: Physical Processes (Princeton University Press)
Seager, S., & Deming, D. 2010, ARA&A, 48, 631
Sestito, P., & Randich, S. 2005, A&A, 442, 615
Southworth, J. 2011, MNRAS, accepted [arXiv:1107.1235]
