Spinning up the Surface: Evidence for Planetary Engulfment or Unexpected Angular Momentum Transport?

Tayar, Jamie; Moyano, Facundo D.; Soares-Furtado, Melinda; Escorza, Ana; Joyce, Meridith; Martell, Sarah L.; García, Rafael A.; Breton, Sylvain N.; Mathis, Stéphane; Mathur, Savita; Delsanti, Vincent; Kiefer, Sven; Reffert, Sabine; Bowman, Dominic M.; Van Reeth, Timothy; Shetye, Shreeya; Gehan, Charlotte; Grunblatt, Samuel K.
Bibliographical reference

The Astrophysical Journal

Advertised on:
Number of authors
IAC number of authors
Refereed citations
In this paper, we report the potential detection of a nonmonotonic radial rotation profile in a low-mass lower-luminosity giant star. For most low- and intermediate-mass stars, the rotation on the main sequence seems to be close to rigid. As these stars evolve into giants, the core contracts and the envelope expands, which should suggest a radial rotation profile with a fast core and a slower envelope and surface. KIC 9267654, however, seems to show a surface rotation rate that is faster than its bulk envelope rotation rate, in conflict with this simple angular momentum conservation argument. We improve the spectroscopic surface constraint, show that the pulsation frequencies are consistent with the previously published core and envelope rotation rates, and demonstrate that the star does not show strong chemical peculiarities. We discuss the evidence against any tidally interacting stellar companion. Finally, we discuss the possible origin of this unusual rotation profile, including the potential ingestion of a giant planet or unusual angular momentum transport by tidal inertial waves triggered by a close substellar companion, and encourage further observational and theoretical efforts.
Related projects
Helio and Asteroseismology
Helio and Astero-Seismology and Exoplanets Search
The principal objectives of this project are: 1) to study the structure and dynamics of the solar interior, 2) to extend this study to other stars, 3) to search for extrasolar planets using photometric methods (primarily by transits of their host stars) and their characterization (using radial velocity information) and 4) the study of the planetary