High-precision photometry by telescope defocusing – I. The transiting planetary system WASP-5†

  1. John Southworth1,*,
  2. T. C. Hinse2,3,
  3. U. G. Jørgensen2,
  4. M. Dominik4,*,
  5. D. Ricci5,
  6. M. J. Burgdorf6,
  7. A. Hornstrup7,
  8. P. J. Wheatley1,
  9. T. Anguita8,
  10. V. Bozza9,10,
  11. S. Calchi Novati9,10,
  12. K. Harpsøe2,
  13. P. Kjærgaard2,
  14. C. Liebig8,
  15. L. Mancini9,10,
  16. G. Masi11,
  17. M. Mathiasen2,
  18. S. Rahvar12,
  19. G. Scarpetta9,10,
  20. C. Snodgrass13,
  21. J. Surdej5,
  22. C. C. Thöne14,15,
  23. M. Zub8

Article first published online: 11 MAY 2009

DOI: 10.1111/j.1365-2966.2009.14767.x

Issue

Monthly Notices of the Royal Astronomical Society

Monthly Notices of the Royal Astronomical Society

Volume 396, Issue 2, pages 1023–1031, June 2009

Additional Information

How to Cite

Southworth, J., Hinse, T. C., Jørgensen, U. G., Dominik, M., Ricci, D., Burgdorf, M. J., Hornstrup, A., Wheatley, P. J., Anguita, T., Bozza, V., Novati, S. C., Harpsøe, K., Kjærgaard, P., Liebig, C., Mancini, L., Masi, G., Mathiasen, M., Rahvar, S., Scarpetta, G., Snodgrass, C., Surdej, J., Thöne, C. C. and Zub, M. (2009), High-precision photometry by telescope defocusing – I. The transiting planetary system WASP-5. Monthly Notices of the Royal Astronomical Society, 396: 1023–1031. doi: 10.1111/j.1365-2966.2009.14767.x

Author Information

  1. 1

    Department of Physics, University of Warwick, Coventry CV4 7AL

  2. 2

    Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, Copenhagen Ø 2100, Denmark

  3. 3

    Armagh Observatory, College Hill, Armagh BT61 9DG

  4. 4

    SUPA, University of St Andrews, School of Physics and Astronomy, North Haugh, St Andrews KY16 9SS

  5. 5

    Institut d'Astrophysique et de Géophysique, Université de Liège, 4000 Liège, Belgium

  6. 6

    Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD

  7. 7

    National Space Institute, Technical University of Denmark, Juliane Maries Vej 30, Copenhagen Ø 2100, Denmark

  8. 8

    Astronomisches Rechen-Institut, Zentrum für Astronomie, Universität Heidelberg, Mönchhofstrasse 12-14, 69120 Heidelberg, Germany

  9. 9

    Dipartimento di Fisica ‘E. R. Caianiello’, Università di Salerno, Baronissi, Italy

  10. 10

    Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Italy

  11. 11

    Bellatrix Observatory, Centre for Backyard Astrophysics, Ceccano (FR), Italy

  12. 12

    Sharif University of Technology, Tehran, Iran

  13. 13

    European Southern Observatory, Casilla 19001, Santiago 19, Chile

  14. 14

    Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, Copenhagen Ø 2100, Denmark

  15. 15

    INAF, Osservatorio Astronomico di Brera, 23807 Merate, Italy

* E-mail: j.k.taylor@warwick.ac.uk
Royal Society University Research Fellow.

  • †

    Based on data collected by Microlensing Network for the Detection of Small Terrestrial Exoplanets (MiNDSTEp) with the Danish 1.54-m telescope at the ESO La Silla Observatory.

Publication History

  1. Issue published online: 10 JUN 2009
  2. Article first published online: 11 MAY 2009
  3. Accepted 2009 March 11. Received 2009 March 6; in original form 2009 January 5

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Keywords:

  • methods: data analysis;
  • methods: observational;
  • techniques: photometric;
  • binaries: eclipsing;
  • stars: individual: WASP-5;
  • planetary systems

ABSTRACT

We present high-precision photometry of two transit events of the extrasolar planetary system WASP-5, obtained with the Danish 1.54-m telescope at European Southern Obseratory La Silla. In order to minimize both random and flat-fielding errors, we defocused the telescope so its point spread function approximated an annulus of diameter 40 pixel (16 arcsec). Data reduction was undertaken using standard aperture photometry plus an algorithm for optimally combining the ensemble of comparison stars. The resulting light curves have point-to-point scatters of 0.50 mmag for the first transit and 0.59 mmag for the second. We construct detailed signal-to-noise ratio calculations for defocused photometry, and apply them to our observations. We model the light curves with the jktebop code and combine the results with tabulated predictions from theoretical stellar evolutionary models to derive the physical properties of the WASP-5 system. We find that the planet has a mass of Mb= 1.637 ± 0.075 ± 0.033 MJup, a radius of Rb= 1.171 ± 0.056 ± 0.012 R Jup, a large surface gravity of gb= 29.6 ± 2.8 m s−2 and a density of ρb= 1.02 ± 0.14 ± 0.01 ρJup (statistical and systematic uncertainties). The planet's high equilibrium temperature of Teq= 1732 ± 80 K makes it a good candidate for detecting secondary eclipses.

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