Speaker
Description
Magnetic active stars, manifest in chromospheric and coronal emissions and offer insights into stellar evolution, magnetic dynamo mechanisms, and their interaction with surrounding environments. Using the SARAO MeerKAT Galactic Plane Survey (SMGPS), an $L$-band survey centred at 1.3 GHz, we investigated chromospheric and coronal activity in stars in the Galactic Plane. Coronal active stars were initially identified through SMGPS cross-correlation with soft X-ray (0.2 – 2.3 keV) eROSITA observations. Chromospheric activity was confirmed through optical spectroscopic follow-up for 29 stars, all exhibiting Ca II H $\&$ K and $H\alpha$ emission lines. To quantify the chromospheric activity, we calculated the S-index, which measures the strength of the H and K lines, and the activity index, $R_{HK}^{\prime}$, the ratio of the emission in the core of the Ca II H $\&$ K lines to the total bolometric emission of the star. The majority of the stars exhibit strong chromospheric activity with an activity index above the Sun's minimum activity. We also examined the relationship between the radio luminosity observed in SMGPS and the X-ray luminosity with eROSITA. The luminosities are correlated and obey the Gudel–Benz relationship confirming that the radio emission is mildly relativistic gyrosynchrotron emission whereas the X-ray emission is thermal emissions in the stellar coronae driven by magnetic reconnection. These properties are commonly associated with main-sequence binaries and single late-type stars.
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