Joint Physics Dept.–Inst. for Space Weather Sci. Colloquium

April 23, Thursday (** SPECIAL DAY**)

Coronal dimmings and their relevance for solar and stellar coronal mass ejections

Prof. Astrid Veronig

University of Graz, Austria

(Solar Physics, Host: Bin Chen)

**Special Room: 463 Tiernan (Big conference room)

**Special Time: 1pm - 2pm with 12:45 pm teatime

**ZOOM Meeting ID for those who cannot attend in-person:

955 9399 6954

(APPROVAL by Prof Ahn REQUIRED for APPH/MTSE PhD Students to attend online)

*Password: check email or request from kenahn@njit.edu

Coronal dimmings are sudden decreases of the solar extreme ultraviolet (EUV) and soft X-ray (SXR) emission that occur during the initial stages of a coronal mass ejection (CME). From the solar observations, we know that dimming regions map to the bipolar ends of closed magnetic field lines that become stretched or temporarily opened during an eruption. The transient decrease of the emission is a result of the depletion of coronal plasma caused by the expansion and mass loss due to the CME. Coronal dimmings are regularly observed in solar EUV and SXR imagery, but can be also detected in Sun-as-a-star EUV spectra and light curves. Recently, analogous signals have been found in EUV and SXR light curves of solar-like and late-type stars in the aftermath of flares, indicative of the mass loss due to a flare-associated stellar CME. In this talk, I will give an overview on the rich diagnostics potential offered by coronal dimmings for the understanding of CMEs, and present selected results along three main lines:

1. how coronal dimmings are related to decisive properties of a CME,

2. how they can give us insight into the magnetic flux systems that are involved in the eruption,

3. and how they can be used as a diagnostics of stellar coronal mass ejections.