The place of the Sun among the Sun-like stars. (arXiv:1303.2245v1 [astro-ph.SR])

The place of the Sun among the Sun-like stars. (arXiv:1303.2245v1 [astro-ph.SR]):
Context. Monitoring of the photometric and chromospheric HK emission data
series of stars similar to the Sun in age and average activity level showed
that there is an empirical correlation between the average stellar
chromospheric activity level and the photometric variability. In general, more
active stars show larger photometric variability. Interestingly, the
measurements and reconstructions of the solar irradiance show that the Sun is
significantly less variable than indicated by the empirical relationship. Aims.
We aim to identify possible reasons for the Sun to be currently outside of this
relationship. Methods. We employed different scenarios of solar HK emission and
irradiance variability and compared them with available time series of Sun-like
stars. Results. We show that the position of the Sun on the diagram of
photometric variability versus chromospheric activity changes with time. The
present solar position is different from its temporal mean position as the
satellite era of continuous solar irradiance measurements has accidentally
coincided with a period of unusually high and stable solar activity. Our
analysis suggests that although present solar variability is significantly
smaller than indicated by the stellar data, the temporal mean solar variability
might be in agreement with the stellar data. We propose that the continuation
of the photometric program and its expansion to a larger stellar sample will
ultimately allow us to constrain the historical solar variability.