OBLIQUITIES OF HOT JUPITER HOST STARS: EVIDENCE FOR TIDAL INTERACTIONS AND PRIMORDIAL MISALIGNMENTS

By S. Albrecht, J. Winn, J. Johnson, Andrew W. Howard, G. Marcy, R. P. Butler, P. Arriagada, J. Crane, S. Shectman, I. Thompson and 3 more. 2012

402 citations recorded by the source corpus.

We provide evidence that the obliquities of stars with close-in giant planets were initially nearly random, and that the low obliquities that are often observed are a consequence of star–planet tidal interactions. The evidence is based on 14 new measurements of the Rossiter–McLaughlin effect (for the systems HAT-P-6, HAT-P-7, HAT-P-16, HAT-P-24, HAT-P-32, HAT-P-34, WASP-12, WASP-16, WASP-18, WASP-19, WASP-26, WASP-31, Gl 436, and Kepler-8), as well as a critical review of previous observations. The low-obliquity (well-aligned) systems are those for which the expected tidal timescale is short, and likewise the high-obliquity (misaligned and retrograde) systems are those for which the expected timescale is long. At face value, this finding indicates that the origin of hot Jupiters involves dynamical interactions like planet–planet interactions or the Kozai effect that tilt their orbits rather than inspiraling due to interaction with a protoplanetary disk. We discuss the status of this hypothesis and the observations that are needed for a more definitive conclusion.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/bf3b0c405e66f2f1f5042bea30adf913b3fbff8c

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In Astronomy and Astrophysics

1. Jon Fortney
2. N. Madhusudhan
3. D. Charbonneau
4. J. Winn
5. J. Johnson
6. D. Deming
7. Timothy Morton
8. H. Knutson

Citations in the corpus

• HST hot-Jupiter transmission spectral survey: evidence for aerosols and lack of TiO in the atmosphere of WASP-12b (2013, background): “Alternatively, the low vsini could also be a result of a near pole-on view of the star as seen from the Earth, which is consistent with the spin-orbit misalignment measurement from Albrecht et al. (2012).”
• ORBITAL PHASE VARIATIONS OF THE ECCENTRIC GIANT PLANET HAT-P-2b (2013, background): “In addition, HAT-P2b’s parent star is almost precisely on the Teff = 6250K boundary at which stars empirically appear to be able to maintain misalignment over multi-Gyr time scales (Albrecht et al. 2012).”
• The Eccentric Kozai-Lidov Effect and Its Applications (2016, background): “…planet or stellar dynamical interactions 32 Smadar Naoz is motivated by the presence of substantial eccentricities amongst the more distant Jovian population, and the discovery of high obliquities (misalignments between planetary orbital and host star spin directions, e.g., Albrecht et al. 2012b).”
• A STUDY OF THE SHORTEST-PERIOD PLANETS FOUND WITH KEPLER (2014, background): “…axes are frequently misaligned with the planetary orbits, as is the case with hot Jupiters (see, e.g., Winn et al. 2010; Triaud et al. 2010; Albrecht et al. 2012), or whether they have low obliquities similar to many of the multi-transit host stars that have been measured (Sanchis-Ojeda et…”
• Determining stellar macroturbulence using asteroseismic rotational velocities from Kepler (2014, background): “…orbital axes of the planets in the Solar System are aligned to within ∼7◦ (Beck & Giles 2005), it is now known that some exoplanets c© 2014 RAS have orbits that are significantly misaligned with respect to the stellar equator (e.g. Hébrard et al. 2008; Triaud et al. 2010; Albrecht et al. 2012).”
• Asteroseismology of Solar-Type and Red-Giant Stars (2013, background): “Observations of the Rossiter-McLaughlin (RM) effect and use of spotcrossing events during exoplanet transits have provided estimates of the skyprojected angle between the planetary orbital axis and the stellar rotation axis in more than 50 systems (Albrecht et al. 2012).”
• ROTATION AND WINDS OF EXOPLANET HD 189733 b MEASURED WITH HIGH-DISPERSION TRANSMISSION SPECTROSCOPY (2015, methodology): “The RM e↵ect is often used to measure the projected obliquities (e.g. Hébrard et al. 2008; Albrecht et al. 2012) and for the case of HD 189733 b good alignment was found (Winn et al. 2006; Triaud et al. 2009; Collier Cameron et al. 2010).”
• The Occurrence and Architecture of Exoplanetary Systems (2014, background): “Measurements of stellar obliquity have revealed a wide range of configurations, including stars with lower obliquities than the Sun (e.g., HD 189733; Winn et al. 2006), stars with moderate tilts (e.g., XO-3; Hébrard et al. 2008, Winn et al. 2009, Hirano et al. 2011), stars that are apparently spinn”
• SWEET-Cat: A catalogue of parameters for Stars With ExoplanETs - I. New atmospheric parameters and masses for 48 stars with planets (2013, background): “More recently, the temperature and age of the star was shown present a correlation with the alignement of the stellar spinorbital plane angle (Winn et al. 2010; Triaud 2011; Albrecht et al. 2012), a result that hints at the mechanisms responsible for the migration of hot jupiters.”
• WASP-47: A HOT JUPITER SYSTEM WITH TWO ADDITIONAL PLANETS DISCOVERED BY K2 (2015, background): “Studies of the Rossiter-McLaughlin effect have also found the fingerprints of high eccentricity migration (Albrecht et al. 2012).”
• ECCENTRICITY GROWTH AND ORBIT FLIP IN NEAR-COPLANAR HIERARCHICAL THREE-BODY SYSTEMS (2013, background): “Observations of the sky-projected obliquity angle of Hot Jupiters shows that their orbital orientation ranges from almost perfectly aligned to almost perfectly antialigned with respect to the spin of the star (Albrecht et al. 2012).”
• The California-Kepler Survey. I. High-resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets (2017, methodology): “In addition, a comparison of the V sin i values for 43 stars with Rossiter-McLaughlin of transiting giant planets (Albrecht et al. 2012) and SpecMatch analyses showed agreement at the level of 2 km s−1 or better.”
• INTERNAL GRAVITY WAVES IN MASSIVE STARS: ANGULAR MOMENTUM TRANSPORT (2013, background): “If one resorts to the equilibrium tide for dissipation of obliquity, as in Albrecht et al. (2012b), the semi-major axis is simultaneously damped and the planets will fall into their host stars.”
• The Apparently Decaying Orbit of WASP-12b (2017, background): “The star’s equator is likely to be misaligned with the orbital plane (Schlaufman 2010; Albrecht et al. 2012).”
• GIANT PLANETS ORBITING METAL-RICH STARS SHOW SIGNATURES OF PLANET–PLANET INTERACTIONS (2013, background): “However, it may result from stellar torques on the proto-planetary disk (Batygin 2012), gravity waves that misalign the star’s spin axis (Rogers et al. 2012), or two regimes for tidal realignment (Winn et al. 2010; Albrecht et al. 2012).”
• WASP-121 b: a hot Jupiter close to tidal disruption transiting an active F star (2015, result): “This result could favor Q′?,0 values & 10 7 for WASP-121, which would be in line with the expectation that hot stars (Teff > 6250 K) would have low tidal dissipation efficiencies due to their thin or quasi-nonexistent convective envelopes (see e.g. Winn et al. 2010, Albrecht et al. 2012).”
• FRIENDS OF HOT JUPITERS. I. A RADIAL VELOCITY SEARCH FOR MASSIVE, LONG-PERIOD COMPANIONS TO CLOSE-IN GAS GIANT PLANETS (2013, background): “…the linear trend slope term is fixed to zero (see Tables 10 and 11 for the full solution). d Our values differ from those of previous fits, which did not include the measured secondary eclipse times. e REFERENCES FOR ORBITAL INCLINATIONS AND SPIN-ORBIT ANGLES - (1) Torres et al. (2008); (2)…”
• Tidal Dissipation in Stars and Giant Planets (2014, background): “Albrecht et al. (2012) compiled a set of 53 observed systems and argued that the aligned systems are those in which the timescale for spin–orbit alignment is shorter than the age.”