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Stellar Pulsations Excited by Planetary Tides in WASP-33

Explore the hybrid D Sct and g Dor pulsations in WASP-33, resonating with its retrograde planet’s orbit. Learn about high-order g-mode excitation by planetary tidal forces and the complex ground track intersections. Discover the intriguing world of stellar surfing and pulsation modes.

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Stellar Pulsations Excited by Planetary Tides in WASP-33

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  1. Stellar Pulsations Excited by Planetary Tides in WASP-33 1University of St Andrews, United Kingdom, 2Thueringer LandessternwarteTautenburg, Germany, 3University of British Columbia, Canada, 4Instituto de Astrofsica de Andalucia, Spain, 5Jodrell Bank Centre for Astrophysics, United Kingdom, 6Carnegie Institution of Washington, 7Keele University, United Kingdom, 8Nordic Optical Telescope Scientific Association, Spain, 91234 Hewlett Place, Canada. Andrew Cameron1, E. Guenther2, J. M. Matthews3, J. Telting8, P. J. Amado4, I. McDonald5, E. Shkolnik6, A. M. S. Smith7, G. A. H. Walker9, MOST Science Team

  2. H-R diagram for transit-planet hosts HD 15082 = WASP-33 Data from F. Pont, http://www.inscience.ch/transits/

  3. WASP transit detection Transit period = 1.2199 days; Rp = 1.53 Rjup

  4. A fast rotator – with pulsations Collier Cameron et al 2010, MNRAS 407, 507 Mp < 4 M jup v sin i = 86 km/sec

  5. Doppler shadow of WASP-33b Tautenburg 2008 Oct 18 McDonald 2008 Nov 12 Time Velocity NOT/Fies 2009 Dec 8 Collier Cameron et al 2010, MNRAS 407, 507

  6. WASP-33 is young 1 Gyr 795 Myr 630 Myr 320 Myr 63 Myr Stellar density = 0.479 ± 0.007 solar

  7. d Scuti pulsations in HD15082 Herrero et al A&A 526, L10 (2011)

  8. WASP-33 and the instability strip d Scuti pulsators g Dor pulsators HD 15082 = WASP-33 OGLE2-TR-L9 HAT-P-6, HAT-P-14 WASP-17 Catanzaro et al, MNRAS 411, 1167 (2011)

  9. MOST WASP-33 campaign 2010 45615 data points 20 planetary orbits De-trended MOST light curve of WASP-33, 2010 October 7 - 31

  10. Coherent pulsations: 20 orbits 3fMOST 2fMOST fMOST MOST light curve phase-binned on transit ephemeris 14.2 28.4 42.6

  11. Coherent pulsations: 20 orbits 12.0077 ftransit MOST spacecraft orbit modulation removed 9.8444 ± 0.0004 c/day 21.07 1.9 20.54 34.12 56.77

  12. Resonance or coincidence? Scan hypothetical orbital frequencies from ftrial =12 forb/13 to 12 forb/11 Pick harmonic f = nftrial yielding lowest c2 in range n = 1 … 70. Fraction of trials yielding c2 < c2(12 forb) = 0.017 Reject chance alignment with a strong peak, with 98.3% confidence. forb c2(12 forb)

  13. Ground tracks on wave pattern Apparent pattern period: Ppattern = mPpuls If Ppattern ~ Prot and 86 km s–1< veq< 200km s–1then 3 < m < 8 Orbital period: Porb = 12 Ppuls How many nodes does the planet’s ground track cross? m=3 4 rotations:1 orbit m=5 12:5 m=4 3:1 m=6 2:1 m=7 12:7 m=8 4:3

  14. Resonant retrograde ground-tracks m=5,l=16 m=3,l=6 Too complex? Just right? m=7,l=20 m=7,l=10 Just right? Too complex?

  15. Spectral surf patterns McDonald 2008 Nov 12 m=3,l=6, i=55o NOT/Fies 2009 Dec 8 m=7,l=10, i=55o

  16. Conclusions • HD15082 = WASP-33 is a hybrid d Sct (Herrero et al 2011) + g Dor pulsator • Cf. HD 209295 (Handler et al. 2002), HD 8801 (Henry & Fekel 2005), BD+18 4914 (MOST; Rowe et al 2006), HD 114839 (MOST; King et al 2006), numerous new examples from KEPLER (Balona et al 2011; Catanzaro et al 2001) • Strongest pulsation mode (f = 9.84 c/day) resonates with retrograde planet’s orbit: Ppattern = m Porb / 12 • High-order g-mode excited by planetary tidal bulge passing over nodes of pulsation pattern. • Is extreme stellar surfing a survivable sport for close-in planets?

  17. g Dor + d Sct pulsators • g Dor • f < 5-10 c/day • high radial order g-modes • convective blocking • d Sct • f > 5 c/day • Low-order radial, nonradial g and p modes • He II ionization opacity Catanzaro et al 2011: KEPLER hybrids

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