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Title: Why are hot Jupiters around hotter stars often misaligned?
Plain: Around cool stars, hot Jupiters usually orbit in the plane of the star's equator; around hotter stars their orbits are often tilted or even backward. Either tides straighten orbits only around cool stars, or the planets arrived differently.
Precise: Stellar obliquities measured by the Rossiter-McLaughlin effect are mostly small for host stars with $T_{\mathrm{eff}} < 6250\,\mathrm{K}$ and broadly distributed above. Determine whether this reflects tidal realignment acting through the convective envelope of cool stars or a primordial difference in formation, and determine the tidal dissipation rate needed for realignment without orbital decay.
Settled by: Obliquity distributions versus stellar age, mass and planet mass for a large sample, compared with tidal models that predict realignment and decay together.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: open
Status note: (empty)
Posed since: 2010