Solar and stellar CMEs: characterization by coronal dimmings

Short Description

Starting point / motivation

Coronal dimmings contain crucial information on the initiation, evolution and plasma properties of coronal mass ejections (CMEs), i.e. the most energetic eruptions from our Sun. They appear as transient regions of strongly reduced emission at EUV and SXR wavelengths during the early CME evolution, and are explained by the density depletion caused by the evacuation of plasma due to the CME lift off.

Contents and goals

The present proposal offers an innovative study using coronal dimming measures to determine characteristic CME properties relevant for the prediction of space weather disturbances at Earth, and to explore the innovative potential of coronal dimmings to detect CMEs on late-type main-sequence stars.

In the highly successful predecessor ASAP-11 project CORDIM, we combined the unique simultaneous multi-point observations of CMEs (observed on the limb by at least one of the twin STEREO satellites) and coronal dimmings (observed on-disk by SDO).

We could establish various distinct statistical relations between decisive CME properties (speed, mass, timing) and parameters of the associated coronal dimming (size, intensity drop, drop rate, timing).

Based on these fundamental findings we have obtained, we will in the present project pursue the following main aims: 

  1. to use coronal dimming measurements to estimate the speed, mass and 3D propagation direction for fast Earth-directed CMEs,
  2. benchmark the relations between spatially resolved and unresolved ("Sun-as-a-star") coronal dimming parameters and their corresponding CME properties, and
  3. use these solar results to establish a new method to identify signatures of stellar CMEs.


We will make use of the solar EUV (imaging and spectroscopy) and white-light (coronagraph) observations from the NASA and ESA satellites SDO, STEREO, SOHO and Proba-2, as well as of the stellar observations from DLR’s ROSAT satellite, ESA’s XMM-Newton, and NASA’s EUVE.

Expected results

Aims 1 and 2 offer a new approach to characterize Earth-directed CMEs based on on-disk EUV imaging data. The results obtained will provide a conceptual basis to build a real-time system of characterizing and alerting of space-weather threatening CMEs based on EUV imagers, relevant for ESA’s SSA programme.

In aim 3, we strive to establish a new approach how to detect CMEs on stars. Such attempts are highly relevant, as presently there exist no proper means to identify stellar CMEs. However, the CME-productivity of a star has turned out to be a crucial factor in determining the habitability of the exoplanets the star is hosting and also affects its evolution.

If our approach to identify and characterize CME signatures in the flare light curves of stars is successful, this will provide a new window on the research on stellar CMEs.


Project Partners


University of Graz - Institute of Physics, Department of Geophysics, Astrophysics and Meteorology

Contact Address

University of Graz
Institute of Physics
Department of Geophysics,
Astrophysics and Meteorology
Prof. Dr. Astrid Veronig
Universitätsplatz 5/II
A-8010 Graz