Search Publications

Does the radial-tangential macroturbulence model adequately describe the spectral line broadening of solar-type stars?*

Takeda, Yoichi; UeNo, Satoru

In incorporating the effect of atmospheric turbulence in the broadening of spectral lines, the so-called radial-tangential macroturbulence (RTM) model has been widely used in the field of solar-type stars, which was devised from intuitive appearance of the granular velocity field of the Sun. Since this model assumes that turbulent motions are rest…

Validation of a scaling law for the coronal magnetic field strength and loop length of solar and stellar flares

Namekata, Kosuke; Shibata, Kazunari; Watanabe, Kyoko +2 more

Shibata and Yokoyama (1999, ApJ, 526, L49; 2002, ApJ, 577, 422) proposed a method of estimating the coronal magnetic field strength (B) and magnetic loop length (L) of solar and stellar flares, on the basis of magnetohydrodynamic simulations of the magnetic reconnection model. Using the scaling law provided by Shibata and Yokoyama (1999, ApJ, 526,…

A study of the long term evolution in active region upflows

Harra, Louise K.; Ugarte-Urra, Ignacio; Baker, Deborah +5 more

Since their discovery, upflows at the edges of active regions have attracted a lot of interest, primarily as they could potentially contribute to the slow solar wind. One aspect that has not been studied yet is how the long term evolution of active regions impacts the upflows. In this work, we analyze one active region that survives three solar ro…

Observational study on the fine structure and dynamics of a solar jet. I. Energy build-up process around a satellite spot

Shibata, Kazunari; Ichimoto, Kiyoshi; Ueno, Satoru +3 more

We report on a solar jet phenomenon associated with successive flares on 2014 November 10. These explosive events were involved with the satellite spots' emergence around a δ-type sunspot in the decaying active region NOAA 12205. The data for this jet were provided by the Solar Dynamics Observatory, the X-Ray Telescope aboard Hinode, and the Inter…

Temporal relations between magnetic bright points and the solar sunspot cycle

Van Doorsselaere, Tom; Utz, Dominik; Muller, Richard

The Sun shows a global magnetic field cycle traditionally best visible in the photosphere as a changing sunspot cycle featuring roughly an 11-year period. In addition we know that our host star also harbours small-scale magnetic fields often seen as strong concentrations of magnetic flux reaching kG field strengths. These features are situated in …