Simultaneous observations of the young Sun Iota-Horologii
Abstract
A simultaneous and revealing stellar analysis has been performed on the young Sun-like star iota-Horologii. The star has one the shortest reported magnetic cycle, of about 1.4 years. That short period, in comparison with the 22 years solar magnetic cycle, allowed a faster activity analysis of a young Sun. We compiled a long-term spectropolarimetric follow-up under the "Far beyond the Sun" campaign of about 6 observational semesters. During the last semester of observation, we combined simultaneous observations of the star by TESS and HST satellites. Those observations let us compare the stellar activity for different atmospheric stratifications. By using the GPS method combined, for the first time, with Zeeman Doppler Imaging (ZDI) mapping technique we constrained the faculae to spot driver ratio. Such combined information helps us to better interpret the stellar surface. We found that the stellar surface is spot-dominated, with a facular to spot ratio (Sfac/Sspot)(Sfac/Sspot) of about 0.74. For reference, the Sun displays a roughly constant (Sfac/Sspot)(Sfac/Sspot) about 3, faculae dominated surface along its activity cycle. We retrieved diagnostics of the coronal transition region, derived from the Oiv and Siv inter-combination lines observed by HST. We describe and place our results in the context of the correlations between the different observables, which improves the magnetic activity characterization for the different atmospheric layers.
- Publication:
-
The 20.5th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (CS20.5)
- Pub Date:
- March 2021
- DOI:
- 10.5281/zenodo.4562397
- Bibcode:
- 2021csss.confE..63A
- Keywords:
-
- Cool Stars on the main sequence;
- Facula to spot ratio;
- Stellar activity;
- TESS photometry;
- HST observations;
- HARPS Spectropolarimetry;
- Iota Horologii