Stellar activity

Title:

Stellar activity

Creator:

Rodono, Marcello

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:a156b562-25aa-4bba-8282-a5e36c6262df
uuid:a156b562-25aa-4bba-8282-a5e36c6262df

Subject:

astrophysics, solar-type magnetic activity, and stellar activity

Type:

model:article and TEXT

Format:

bez média and svazek

Description:

After reviewing the various aspects of solar-type magnetic activity, which occur in ttie atmospheres of late-type stars on time scales ranging from tens of seconds to years, the principal characterlstics of inhomogeneous localized structures, such as starspots and plages, as derived from modelling the rotation-induced modulation of continuum or line fluxes and high-resolution UV emission line profiles of Mg II by the Doppler imaging technique, were critically presented by taking into account the present observational limits. It was shown that the geometrical and energetic characteristics of magnetic activity phenomena on stars overcome by orders of magnitude the corresponding solar phenomena. However, stellar activity appears to be solar-like as far as it concerns its origin and evolution: active stars have deep convection zones and, possibly, differential rotation, so that solar-type dynamos can efficiently operate. Nevertheless, in order to detect strictly solar activity signatures on stars, the photometric precision, the spectral - and time - resolutlon of stellar observations need to be improved by at least one order of magnitude. In partlcular, the time scales of stellar flares and the accurate timing smáli solar-type spot appearance on and disappearance from the visible disk of a rotating star were Indicated as priority observational objectives for the purpose of establishing the minimum flare duration and spot slze, which are important parameters to constrain theoretical models. 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.

Language:

Czech

Rights:

http://creativecommons.org/publicdomain/mark/1.0/
policy:public

Coverage:

89-90

Source:

Publications of the Astronomical Institute of the Academy of Sciences of the Czech Republic | 1987 Volume:63-70 | Number:70

Harvested from:

CDK

Metadata only:

false