WASP-38b: a transiting exoplanet in an eccentric, 6.87d period orbit

S. C. C. Barros*, F. Faedi, A. Collier Cameron, T. A. Lister, J. McCormac, D. Pollacco, E. K. Simpson, B. Smalley, R. A. Street, I. Todd, A. H. M. J. Triaud, I. Boisse, F. Bouchy, G. Hebrard, C. Moutou, F. Pepe, D. Queloz, A. Santerne, D. Segransan, S. UdryJ. Bento, O. W. Butters, B. Enoch, C. A. Haswell, C. Hellier, F. P. Keenan, G. R. M. Miller, V. Moulds, A. J. Norton, N. Parley, I. Skillen, C. A. Watson, R. G. West, P. J. Wheatley

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

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Aims. We report the discovery of WASP-38b, a long period transiting planet in an eccentric 6.871815 day orbit. The transit epoch is 2 455 335.92050 +/- 0.00074 (HJD) and the transit duration is 4.663 h.

Methods. WASP-38b's discovery was enabled due to an upgrade to the SuperWASP-North cameras. We performed a spectral analysis of the host star HD 146389/BD + 10 2980 that yielded T-eff = 6150 +/- 80 K, log g = 4.3 +/- 0.1, v sin i = 8.6 +/- 0.4 km s(-1), M-* = 1.16 +/- 0.04 M-circle dot and R-* = 1.33 +/- 0.03 R-circle dot, consistent with a dwarf of spectral type F8. Assuming a main-sequence mass-radius relation for the star, we fitted simultaneously the radial velocity variations and the transit light curves to estimate the orbital and planetary parameters.

Results. The planet has a mass of 2.69 +/- 0.06 M-Jup and a radius of 1.09 +/- 0.03 R-Jup giving a density,rho(p) = 2.1 +/- 0.1 rho(J). The high precision of the eccentricity e = 0.0314 +/- 0.0044 is due to the relative transit timing from the light curves and the RV shape. The planet equilibrium temperature is estimated at 1292 +/- 33 K. WASP-38b is the longest period planet found by SuperWASP-North and with a bright host star (V = 9.4 mag), is a good candidate for followup atmospheric studies.

Original languageEnglish
Article number54
Number of pages6
JournalAstronomy and Astrophysics
Publication statusPublished - Jan 2011


  • planets and satellites: detection
  • stars: individual: WASP-38
  • techniques: photometric
  • techniques: radial velocities
  • HD 189733B

Cite this

Barros, S. C. C., Faedi, F., Cameron, A. C., Lister, T. A., McCormac, J., Pollacco, D., Simpson, E. K., Smalley, B., Street, R. A., Todd, I., Triaud, A. H. M. J., Boisse, I., Bouchy, F., Hebrard, G., Moutou, C., Pepe, F., Queloz, D., Santerne, A., Segransan, D., ... Wheatley, P. J. (2011). WASP-38b: a transiting exoplanet in an eccentric, 6.87d period orbit. Astronomy and Astrophysics, 525, [54]. https://doi.org/10.1051/0004-6361/201015800