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Observation and models of solar and stellar active regions at radio wavelengths (mm/sub-mm)

Abstract

While in the optical, the solar surface shows the presence of dark sunspots (umbra and penumbra), at radio wavelengths those active regions can be brighter than the quiet Sun due to the local atmosphere temperature increase. This temperature increase at radio frequencies can be due to distinct emission mechanisms, usually bremsstrahlung and gyroresonance. Resent results showed that active regions with intense magnetic fields can keep the dark sunspot umbra at mm and sub-mm wavelengths, differing of the classical centimetric observations, that always presented the umbra brighter than the quiet Sun. Make active regions models at mm/sub-mm became very important for the new radio telescopes, like ALMA and LLAMA, which are able to observe the Sun. These models will be also used to investigate the radio emission of active regions of solar type stars, which present darker and colder spots and more intense magnetic fields than the observed on the Sun. (AU)

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Scientific publications (12)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
MENEZES, FABIAN; SELHORST, CAIUS L.; GIMENEZ DE CASTRO, CARLOS GUILLERMO; VALIO, ADRIANA. The Subterahertz Solar Cycle: Polar and Equatorial Radii Derived from SST and ALMA. ASTROPHYSICAL JOURNAL, v. 910, n. 1, . (13/24155-3, 19/03301-8, 13/10559-5)
SELHORST, CAIUS L.; KALLUNKI, JUHA; GIMENEZ DE CASTRO, C. GUILLERMO; VALIO, ADRIANA; COSTA, JOAQUIM E. R.. The Solar Radius at 37 GHz Through Cycles 22 to 24. SOLAR PHYSICS, v. 294, n. 12, . (19/03301-8)
NOWAK, NATALIA; KOWAL, GRZEGORZ; FALCETA-GONCALVES, DIEGO A.. Generation and effects of electromotive force in turbulent stochastic reconnection. Physics of Plasmas, v. 28, n. 6, . (13/10559-5, 19/03301-8)
SILVA, ALEXANDRE JOSE DE OLIVEIRA E; SELHORST, CAIUS LUCIUS; COSTA, JOAQUIM E. R.; SIMOES, PAULO J. A.; DE CASTRO, CARLOS GUILLERMO GIMENEZ; WEDEMEYER, SVEN; WHITE, STEPHEN M.; BRAJSA, ROMAN; VALIO, ADRIANA. A Genetic Algorithm to Model Solar Radio Active Regions From 3D Magnetic Field Extrapolations. FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, v. 9, p. 13-pg., . (13/10559-5, 13/24155-3, 19/03301-8)
VALIO, ADRIANA; SPAGIARI, EDUARDO; MARENGONI, MAURICIO; SELHORST, CAIUS L.. Correlations of Sunspot Physical Characteristics during Solar Cycle 23. SOLAR PHYSICS, v. 295, n. 9, . (13/10559-5, 19/03301-8)
MENEZES, FABIAN; SELHORST, CAIUS L.; GIMENEZ DE CASTRO, CARLOS GUILLERMO; VALIO, ADRIANA. Subterahertz radius and limb brightening of the Sun derived from SST and ALMA. Monthly Notices of the Royal Astronomical Society, v. 511, n. 1, p. 9-pg., . (13/10559-5, 13/24155-3, 19/03301-8)
BRAJSA, R.; SKOKIC, I; SUDAR, D.; BENZ, A. O.; KRUCKER, S.; LUDWIG, H-G; SAAR, S. H.; SELHORST, C. L.. ALMA small-scale features in the quiet Sun and active regions. Astronomy & Astrophysics, v. 651, . (19/03301-8)
MEDINA-TORREJON, TANIA E. E.; DAL PINO, ELISABETE M. DE GOUVEIA M.; KOWAL, GRZEGORZ. Particle Acceleration by Magnetic Reconnection in Relativistic Jets: The Transition from Small to Large Scales. ASTROPHYSICAL JOURNAL, v. 952, n. 2, p. 11-pg., . (13/10559-5, 13/10559-5, 19/03301-8, 21/06502-4, 09/54006-4)
NATIVI, L.; LAMB, G. P.; ROSSWOG, S.; LUNDMAN, C.; KOWAL, G.. Are interactions with neutron star merger winds shaping the jets?. Monthly Notices of the Royal Astronomical Society, v. 509, n. 1, p. 903-913, . (19/03301-8, 13/10559-5)
KOWAL, GRZEGORZ; FALCETA-GONCALVES, DIEGO A.. Colliding-Wind Binaries as a Source of TeV Cosmic Rays. FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, v. 8, . (13/10559-5, 19/03301-8)
SELHORST, CAIUS L.; BARBOSA, CASSIO L.; SIMOES, PAULO; VIDOTTO, ALINE A.; VALIO, ADRIANA. Planetary Transits at Radio Wavelengths: Secondary Eclipses of Hot Jupiter Extended Atmospheres. ASTROPHYSICAL JOURNAL, v. 895, n. 1, . (19/03301-8, 13/10559-5)
MEDINA-TORREJON, TANIA E.; DE GOUVEIA DAL PINO, ELISABETE M.; KADOWAKI, LUIS H. S.; KOWAL, GRZEGORZ; SINGH, CHANDRA B.; MIZUNO, YOSUKE. Particle Acceleration by Relativistic Magnetic Reconnection Driven by Kink Instability Turbulence in Poynting Flux-Dominated Jets. ASTROPHYSICAL JOURNAL, v. 908, n. 2, . (19/03301-8, 13/10559-5, 16/12320-8, 09/54006-4)

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