Astronomy Colloquium (2017 Spring Semester)

* Date

Mar 09

* Speaker

Jeongwoo Lee (Institute for Space-Earth Environmental Research, Nagoya University)

* Title

When the Sun’s Coronal Tail Wags Its Photospheric Dog

* Abstract

The Sun’s corona is an electrically conducting fluid embedded in strong magnetic fields. It is a general belief that solar eruptions triggered in the corona are the direct result of the motion of the dense underlying photosphere. But we recently argued, in a paper published in Nature Communications, that flares in turn have a powerful impact on sunspots to cause them to rotate at much faster speeds than are usually observed before they erupt. These observations, based on high-resolution images captured through NJIT’s 1.6 meter New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO), come as something of a surprise, since the corona has a plasma density about a hundred million times smaller than that of the photosphere. It is analogous to the tail wagging the dog. The key result is that sunspots do not rotate as a whole when the eruption begins. Instead, the rotation starts at one side and gradually spreads across the whole sunspot. This talk will present its implication on the traditional picture for solar flare energy release, along with the details of the data analysis that led to the discovery of the flare-induced sunspot rotation.