Letters of Intent received in 2019

LoI 2021-2060
GA Focus Meeting: solar-stellar connection revealed by magnetic activity and eruptive phenomena

Topics

1. photospheric magnetic activity
2. chromospheric activity
3. coronal activity
4. sunspots and starspots
5. global magnetic field
6. activity cycle and magnetic dynamo process
7. helioseismology and asteroseismology
8. solar and stellar flares
9. solar and stellar mass ejections
10. influence on space weather and planetary habitability

Rationale

Observations reveal that the Sun and the stars possess the common magnetic activity and eruptive phenomena in their atmosphere. The observational approaches include light curve and spectrum observations for both the Sun and the stars and imaging observations mostly for the Sun. The wavelength bands include the white light for photosphere, optical spectral lines for chromosphere, ultraviolet for chromosphere and transition region, and soft X-ray for corona. The radio observations also provide information of solar and stellar magnetic activity. The magnetic features in the photosphere, such as the spots and faculae, cause rotational modulation in the observed solar and stellar light curves. The optical spectral lines such as Ca II H&K and H-alpha can indicate chromospheric activities. Measurements of the stellar magnetic field demonstrate a relatively stronger global magnetic field of stars than that of the Sun. Long-term observations disclose the solar and stellar activity cycles. The stellar magnetic activities revealed by the X-ray observations of space satellites show clear relationship of activity levels with rotation rate of stars, which gives strong implications on the magnetic dynamo process in the convection zones of stars. Like the helioseismology technique for the Sun, the asteroseismology approach can give clues of stellar internal structures as well as the activity on the surface of the stars. The flare activity is a prominent eruptive phenomenon found on both the Sun and the stars. The solar mass ejections in chromosphere and corona are commonly observed on the Sun, and modern observations also provide evidences of chromospheric and coronal mass ejections of stars. These eruptive phenomena may cause significant influence on space weather and planetary habitability. The contemporary time-domain survey missions such as the Kepler and TESS space telescopes provide stellar light curve data with extremely large volume and high temporal resolution. These data greatly advanced our knowledges about the magnetic activity and flares of stars. The statistical and case analyses demonstrate the connections between the solar and stellar magnetic activity and eruptive phenomena in various aspects. The results of these studies also reveal the different magnetic activity properties along with the age, rotation rate, spectral type, evolution stage, and other parameters of stars. The physical models and imaging observations of Sun can provide a framework basis for investigating the physical mechanism of stellar magnetic activity and eruptive phenomena. The knowledges of the stars can extend our physical view of the magnetic activity and eruptive phenomena on the Sun. Any topics concerning the solar and stellar magnetic activity and eruptive phenomena are welcome in this meeting.