The On/Off Nature of Star-Planet Interactions
By E. Shkolnik, D. Bohlender, G. Walker, A. Collier Cameron. Proceedings of the International Astronomical Union, 2007
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Evidence suggesting an observable magnetic interaction between a star and its hot Jupiter appears as a cyclic variation of stellar activity synchronized to the planet's orbit. In this study we monitored the chromospheric activity using several stellar activity indicators of seven stars with hot Jupiters using new high-resolution echelle spectra collected with ESPaDOnS over a few nights in 2005 and 2006 from the CFHT (Ca II H λ3968, K λ3933, the Ca II infrared triplet [IRT] λ8662 line, Hα λ6563, and He I λ5876). Synchronicity of the Ca II H and K emission of HD 179949 with its planet's orbit is clearly seen in four out of six epochs, while rotational modulation with Prot = 7 days is apparent in the other two seasons. We observe a similar phenomenon on υ And. This on/off nature of star-planet interaction (SPI) in the two systems is likely a function of the changing stellar magnetic field structure throughout its activity cycle. Variability in the transiting system HD 189733 is likely associated with an active region rotating with the star; however, the flaring in excess of the rotational modulation may be associated with its hot Jupiter. As for HD 179949, the peak variability as measured by the mean absolute deviation (MAD) for both HD 189733 and τ Boo leads the subplanetary longitude by ~70°. The tentative correlation between this activity and the ratio of Mpsin i to the planet's rotation period, a quantity proportional to the hot Jupiter's magnetic moment, first presented by Shkolnik and coworkers remains viable. This work furthers the characterization of SPI, improving its potential as a probe of extrasolar planetary magnetic fields.
Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics
View Paper: https://www.semanticscholar.org/paper/973fd1f4c2f1001f92bf2ff59d8ac8a4e1071889
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Citations in the corpus
- Magnetic cycles of the planet-hosting star τ Bootis – II. A second magnetic polarity reversal (2009, background): “These SPI episodes are apparently phase shifted with orbital conjunctions (Shkolnik et al. 2005); they are also reported to exhibit longer term fluctuations, suggesting an intermittent (’onoff’) nature of SPI (Shkolnik et al. 2008).”
- The FIP and Inverse FIP Effects in Solar and Stellar Coronae (2015, background): “…interaction has been noted, in that the planet appears to be inducing an active region on the star, that leads the planet by ∼ 70◦ in longitude (Shkolnik et al., 2008; Walker et al., 2008), and this opens the possibility of the planet also affecting the coronal abundances, due to waves…”
- Magnetic energy fluxes in sub-Alfvénic planet star and moon planet interactions (2013, background): “The observed intermittent character of the starplanet interaction by Shkolnik et al. (2008) is explained by a topological change in the stellar coronal field, induced by a variation in its relative helicity.”
- Searching for star–planet interactions within the magnetosphere of HD 189733 (2010, methodology): “Studying the activity of HJ hosting stars, Shkolnik et al. (2003, 2005, 2008) concluded that not all the observed systems show hints”
- THE MUSCLES TREASURY SURVEY. I. MOTIVATION AND OVERVIEW (2016, result): “However, almost every claimed detection of a modulation in activity on exoplanet host stars or connection with orbital phase has not been confirmed by follow up observation or re-analysis of the same data set (e.g., Shkolnik et al. 2008; Poppenhaeger et al. 2010).”
- DISEQUILIBRIUM CARBON, OXYGEN, AND NITROGEN CHEMISTRY IN THE ATMOSPHERES OF HD 189733b AND HD 209458b (2011, background): “…range ∼5050–5090 K (Bouchy et al. 2005; Knutson et al. 2010) and has typically been classified in the literature as a K1V-to-K2V main-sequence star (e.g., Barnes et al. 2010; Shkolnik et al. 2008), although the Hipparcos catalog lists it as a G5V (Perryman et al. 1997; see also Montes et al. 2001).”
- Magnetic activity in the photosphere of CoRoT-Exo-2a. Active longitudes and short-term spot cycle in (2008, background): “It will be interesting to observe CoRoT-Exo-2a from the ground to look for indication of star-planet magnetic interaction in the chromosphere, as recently suggested by Shkolnik et al. (2008) for some stars accompanied by hot Jupiters.”