Small Scale Stellar Surface Structures
The principal characteristics of inhomogeneous localized structures, such as starspots and plages, as derived from modelling the rotation-induced modulation of continuum and line fluxes and from Doppler imaging studies are critically reviewed by taking into account the present observational limits. It is shown that the energetic and geometrical characteristics of magnetic activity phenomena on stars overcome by orders of magnitude the corresponding solar phenomena. However they appear to be solar-type as far as it concerns their origin and evolution: active stars have deep convection zones and, possibly, differential rotation, so that a solar-type dynamo can efficiently operate. Nevertheless, in order to detect strictly solar activity signatures on stars, the photometric precision and spectral resolution of stellar observations need to be improved by at least one order of magnitude. The new generation of very large aperture ground-based telescopes (e.g., ESO-VLT) and space telescopes (e.g., Hubble Space Telescope), together with existing radio observatories (e.g., VLA, VLBI), will need to be used.
KeywordsDifferential Rotation Rotational Modulation Hubble Space Telescope Line Flux Stellar Atmosphere
- Rodonò, M.: 1986, ‘Starspots and plages’, in Highlights of Astronomy, J.P. Swings (ed), Reidel Publ. Co., Dordrecht, p. 429.Google Scholar
- Rodonò, M.: 1986, ‘Rotational modulation of continuum and integrated line fluxes’, in Proc. Fourth Cambridge Workshop on Cool Stars, Stellar System and the Sun, M. Zeilik and D.M. Gibson (eds), Springer-Verlag, p. 475.Google Scholar
- Rodonò, M.: 1987, ‘The atmospheres of M-dwarfs: Observations’, in The atmospheres of M, S, C stars, H.R. Johnson and F. Querci (eds), CNRS-NASA Monograph Series on Non-thermal phenomena in Stellar atmospheres, in press.Google Scholar
- Walter F. M., et al.: 1987, ‘Rotational modulation and flares on RS CVn and BY Dra Stars. IV. The spatially resolved chromosphere of AR Lacertae’ Astron. Astrophys. (in press).Google Scholar