Oral Presentation

The Heating of Coronal Loops and X-ray Emission in Low/Zero-metal Stars

Author(s): Haruka Washinoue (UTokyo); Takeru Suzuki(UTokyo)

Presenter: Haruka Washinoue (The University of Tokyo)

We investigated the heating of coronal loops on solar-type low/zero-metal stars, particularly focusing on the dependence on metallicity. Solar-type stars possess a surface convection zone and the upper atmosphere is heated up to the coronal temperature exceeding 10^6 K. We performed magnetohydrodynamical simulations with thermal conduction and radiative cooling to study roles of the Alfven wave excited by the surface convection in the heating of coronal loops. We found that the coronal density is higher for lower-metallicity stars. As a result, lower-metallicity stars emit higher X-ray flux. Zero-metal stars with the mass less than 0.8 solar mass survive until the present-day, although they have not been discovered yet. Our result indicates such low-mass first stars could be detected as X-raybright stars.