不同金属丰度下的冕环与广义RTV标度律

10秒差距内FGK型恒星的X射线星表：用RTV标度律解释日冕温度-光度关系

The X-ray catalogue of FGK stars within 10 pc: The coronal temperature-brightness relation explained with the RTV scaling law

本研究构建10秒差距内FGK型恒星的X射线星表，用RTV标度律解释日冕温度-光度关系，发现该关系离散度极小，仅三颗恒星为异常值。

Stellar coronal X-ray emission and surface magnetic flux

Observations show that the coronal X-ray emission of the Sun and other stars depends on the surface magnetic field. Using power-law scaling relations between different physical parameters, we build an analytical model to connect the observed X-ray emission to the magnetic flux. The basis for our model are the scaling laws of Rosner, Tucker \& Vaiana (RTV) that connect the temperature and pressure of a coronal loop to its length and energy input. To estimate the energy flux into the upper atmosphere, we use scalings derived for different heating mechanisms, e.g. for field-line braiding or Alfve…

Scaling laws of coronal loops compared to a 3D MHD model of an Active Region

Context. The structure and heating of coronal loops are investigated since decades. Established scaling laws relate fundamental quantities like the loop apex temperature, pressure, length, and the coronal heating. Aims. We test such scaling laws against a large-scale 3D MHD model of the Solar corona, which became feasible with nowadays high-performance computing. Methods. We drive an active region simulation a with photospheric observations and found strong similarities to the observed coronal loops in X-rays and EUV wavelength. A 3D reconstruction of stereoscopic observations showed that our …

Investigation of coronal properties of X-ray bright G-dwarf stars based on the solar surface magnetic field -- corona relation

We investigated the coronal properties of G-dwarf stars including the Sun over a wide range of X-ray luminosity $L_{\rm X}$ ($3\times 10^{26}$ to $2\times 10^{30}~{\rm erg~s^{-1}}$). We analyzed the archival data of ten X-ray bright ($L_{\it X}>10^{28}~{\rm erg~s^{-1}}$) G-dwarf stars to derive their emission measure (EM) and the coronal temperature ($T$) during the periods when no prominent stellar flares were observed. We attempted to explain the relation on the basis of our understanding of the present Sun: a steady corona model based on the so-called RTV scaling laws and the observed power…

Coronae of Zero/Low-Metal Low-Mass Stars

Recent theoretical studies suggest the existence of low-mass zero-metal stars in the current universe. In order to study the basic properties of the atmosphere of low-mass first stars, we performed one dimensional magnetohydrodynamical simulations for the heating of coronal loops on low-mass stars with various metallicities. While the simulated loops are heated up to >$10^6$ K by the dissipation of Alfvenic waves originating from the convective motion irrespectively of the metallicity, the coronal properties sensitively depend on the metallicity. Lower-metal stars create hotter and denser coro…