Abstract
We report the discovery of the planets WASP-20b and WASP-28b along with measurements of their sky-projected orbital obliquities. WASP-20b is an inflated, Saturn-mass planet (0.31 MJup; 1.46 RJup) in a 4.9-day, near-aligned (λ = 12.7±4.2°) orbit around CD-24 102 (V = 10.7; F9). Due to the low density of the planet and the apparent brightness of the host star, WASP-20 is a good target for atmospheric characterisation via transmission spectroscopy. WASP-28b is an inflated, Jupiter-mass planet (0.91 MJup; 1.21 RJup) in a 3.4-day, near-aligned (λ = 8±18°) orbit around a V = 12, F8 star. As intermediate-mass planets in short orbits around aged, cool stars (7+2-1 Gyr and 6000±100 K for WASP-20; 5+3-2 Gyr and 6100±150 K for WASP-28), their orbital alignment is consistent with the hypothesis that close-in giant planets are scattered into eccentric orbits with random alignments, which are then circularised and aligned with their stars' spins via tidal dissipation.
Original language | English |
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Article number | A61 |
Number of pages | 8 |
Journal | Astronomy and Astrophysics |
Volume | 575 |
Early online date | 24 Feb 2015 |
DOIs | |
Publication status | Published - Mar 2015 |
Keywords
- planetary systems
- stars: individual: WASP-20b
- stars: individual: WASP-28b