Abstract
We present the results of a comprehensive numerical simulation of the environment around three exoplanet-host stars (HD 1237, HD 22049, and HD 147513). Our simulations consider one of the latest models currently used for space weather studies in the Heliosphere. Large-scale magnetic field maps, recovered with two implementations of the tomographic technique of Zeeman-Doppler imaging, serve to drive steady-state solutions in each system. This paper contains the description of the stellar wind and inner astrosphere, while the coronal structure was previously discussed in Alvarado-G\'omez et al. (2016). The analysis includes the magneto-hydrodynamical properties of the stellar wind, the associated mass and angular momentum loss rates, as well as the topology of the astrospheric current sheet in each system. A systematic comparison among the considered cases is performed, including two reference solar simulations covering activity minimum and maximum. For HD 1237, we investigate the interactions between the structure of the developed stellar wind, and a possible magnetosphere around the Jupiter-mass planet in this system. We find that the process of particle injection into the planetary atmosphere is dominated by the density distribution rather than velocity profile of the stellar wind. In this context, we predict a maximum exoplanetary radio emission of 12 mJy at 40 MHz in this system, assuming the crossing of a high-density streamer during periastron passage. Furthermore, in combination with the analysis performed in Alvarado-G\'omez et al. (2016), we obtain for the first time a fully simulated mass loss-activity relation, which is compared and discussed in the context of the relation based on astrospheric detections proposed by Wood et al. (2005a). Finally, we provide a characterisation of the 3D properties of the stellar wind of these systems, at the inner edges of their habitable zones.
Highlights
As well as driving stellar activity cycles, magnetic fields strongly influence different aspects of the stellar structure and evolution
Seems to be lower for higher surface field strengths. These differences are related to the radial behaviour of the thermodynamical quantities (i.e. RAS is larger in the SH-ZDI case), and the underlying coronal structure, which in turn depends on additional factors such as the ZDI map resolution, completeness, and field complexity
We carried out elaborated simulations of the stellar wind and inner astrospheric structure of three planet-hosting stars (HD 22049, HD 1237, and HD 147513), using the SWMF (Tóth et al 2005, 2012)
Summary
As well as driving stellar activity cycles, magnetic fields strongly influence different aspects of the stellar structure and evolution. The same is true for the complex interplay between the magnetic field topology, coronal structure, and the stellar wind These elements are fundamental for a better understanding of the environment around planet-hosting stars, including the relative influence of the wind and the high-energy emission on the exoplanetary conditions and habitability (see Lammer et al 2003; Lammer 2013; Shaikhislamov et al 2014; Forget & Leconte 2014). The solar/stellar cases, and the definition of the entire SC component, are identical as in Alvarado-Gómez et al (2016) This includes base conditions typically assumed in high-resolution solar simulations, to match solar observations such as in-situ wind properties at 1 AU and line-of-sight EUV/X-ray images (Sokolov et al 2013; Oran et al 2013). Magnetic field topology at the stellar surface), these are independent from the assumed field strength for the exoplanet
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