English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The measurement of obliquities in star-planet systems is of great importancefor the understanding of planet system formation and evolution. The bright andwell studied HAT-P-7 system is intriguing as several Rossiter-McLaughlin (RM)measurements found a large projected obliquity in this system, but it was sofar not possible to determine if the orbit is polar and/or retrograde. The goalof this study is to measure the stellar inclination and hereby the full 3Dobliquity of the HAT-P-7 system instead of only the 2D projection as measuredby the RM effect. In addition we provide an updated set of stellar parametersfor the star. We use the full set of available observations from Keplerspanning Q0-Q17 to produce the power spectrum of HAT-P-7. We extractoscillation mode frequencies via an MCMC peak-bagging routine, and use theresults from this to estimate the stellar inclination angle. Combining thiswith the projected obliquity from RM and the inclination of the orbital planeallows us to determine the stellar obliquity. We use asteroseismology to modelthe star from the extracted frequencies using two different approaches to themodelling where either the MESA or the GARSTEC stellar evolution codes areadopted. Using our updated asteroseismic modelling we find, i.a., the followingstellar parameters for HAT-P-7: M=1.51{+0.04}{-0.05}Msun,$R=2.00{+0.01}{-0.02}Rsun, and age = 2.07{+0.28}{-0.23} Gyr. Our asteroseismicmodelling offers a high precision on the stellar parameters, for instance isthe uncertainty on age of the order ~11%. For the stellar inclination weestimate i_star<36.5 deg., which translates to an obliquity between 83 and 111deg. We find that the planet HAT-P-7b is likely retrograde in its orbit, andthat the orbit is close to being polar. The new parameters for the star givesan updated planetary density of 0.65+-0.03 g cm^{-3}, which is lower thanprevious estimates.

Asteroseismic inference on the spin-orbit misalignment and stellar parameters of HAT-P-7