WASP-17b

An ultra-low density planet in a probable retrograde orbit

D. R. Anderson, C. Hellier, M. Gillon, A. H M J Triaud, B. Smalley, L. Hebb, A. Collier Cameron, P. F L Maxted, D. Queloz, R. G. West, S. J. Bentley, B. Enoch, K. Horne, T. A. Lister, M. Mayor, N. R. Parley, F. Pepe, D. Pollacco, D. Ségransan, S. Udry & 1 others D. M. Wilson

Research output: Contribution to journalArticle

127 Citations (Scopus)

Abstract

We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses, but 1.5-2 Jupiter radii, giving a density of 6%-14% that of Jupiter. WASP-17b is in a 3.7 day orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a retrograde orbit (λ ≈ -150°), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularization of an eccentric orbit, such as the highly eccentric orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.

Original languageEnglish
Pages (from-to)159-167
Number of pages9
JournalAstrophysical Journal
Volume709
Issue number1
DOIs
Publication statusPublished - 15 Jan 2010
Externally publishedYes

Fingerprint

retrograde orbits
planets
planet
eccentric orbits
Jupiter (planet)
Jupiter
radii
scattering
heating
stars
scale height
Saturn
eclipses
eccentricity
velocity measurement
radial velocity
metallicity
spectroscopy
time measurement
histories

Keywords

  • Planetary systems
  • Stars: individual (WASP-17)

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Anderson, D. R., Hellier, C., Gillon, M., Triaud, A. H. M. J., Smalley, B., Hebb, L., ... Wilson, D. M. (2010). WASP-17b: An ultra-low density planet in a probable retrograde orbit. Astrophysical Journal, 709(1), 159-167. https://doi.org/10.1088/0004-637X/709/1/159

WASP-17b : An ultra-low density planet in a probable retrograde orbit. / Anderson, D. R.; Hellier, C.; Gillon, M.; Triaud, A. H M J; Smalley, B.; Hebb, L.; Cameron, A. Collier; Maxted, P. F L; Queloz, D.; West, R. G.; Bentley, S. J.; Enoch, B.; Horne, K.; Lister, T. A.; Mayor, M.; Parley, N. R.; Pepe, F.; Pollacco, D.; Ségransan, D.; Udry, S.; Wilson, D. M.

In: Astrophysical Journal, Vol. 709, No. 1, 15.01.2010, p. 159-167.

Research output: Contribution to journalArticle

Anderson, DR, Hellier, C, Gillon, M, Triaud, AHMJ, Smalley, B, Hebb, L, Cameron, AC, Maxted, PFL, Queloz, D, West, RG, Bentley, SJ, Enoch, B, Horne, K, Lister, TA, Mayor, M, Parley, NR, Pepe, F, Pollacco, D, Ségransan, D, Udry, S & Wilson, DM 2010, 'WASP-17b: An ultra-low density planet in a probable retrograde orbit', Astrophysical Journal, vol. 709, no. 1, pp. 159-167. https://doi.org/10.1088/0004-637X/709/1/159
Anderson DR, Hellier C, Gillon M, Triaud AHMJ, Smalley B, Hebb L et al. WASP-17b: An ultra-low density planet in a probable retrograde orbit. Astrophysical Journal. 2010 Jan 15;709(1):159-167. https://doi.org/10.1088/0004-637X/709/1/159
Anderson, D. R. ; Hellier, C. ; Gillon, M. ; Triaud, A. H M J ; Smalley, B. ; Hebb, L. ; Cameron, A. Collier ; Maxted, P. F L ; Queloz, D. ; West, R. G. ; Bentley, S. J. ; Enoch, B. ; Horne, K. ; Lister, T. A. ; Mayor, M. ; Parley, N. R. ; Pepe, F. ; Pollacco, D. ; Ségransan, D. ; Udry, S. ; Wilson, D. M. / WASP-17b : An ultra-low density planet in a probable retrograde orbit. In: Astrophysical Journal. 2010 ; Vol. 709, No. 1. pp. 159-167.
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AU - Hebb, L.

AU - Cameron, A. Collier

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AU - Parley, N. R.

AU - Pepe, F.

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