L. Gesztelyi

Hungarian Academy of Sciences

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B. Kálmán

Purple Mountain Observatory

L. Kondás

Hungarian Academy of Sciences

Cheng Fang

Shanxi Medical University

V. Bumba

Czech Academy of Sciences, Astronomical Institute

Katalin Oláh

Eötvös Loránd University

N. Mein

Laboratoire d’études spatiales et d’instrumentation en astrophysique

G. Simon

Galaxies, Etoiles, Physique et Instrumentation

E. H. Avrett

Smithsonian Astrophysical Observatory

R. Falciani

University of Florence

Zs. Kõvári

Konkoly Observatory

Cooperative Institutions

Hungarian Academy of Sciences

Purple Mountain Observatory

Observatoire de Paris

Konkoly Observatory

Czech Academy of Sciences, Astronomical Institute

Research Centre for Astronomy and Earth Sciences

Centre National de la Recherche Scientifique

Czech Academy of Sciences

Ceska Astronomicka Spolecnost

Astronomical Observatory

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Book Review: Solar observations: techniques and interpretation / Cambridge U Press, 1991

Space Science Reviews (1993)

L. Gesztelyi

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White light flares and atmospheric modeling (Working Group report).

M. E. Machado E. H. Avrett R. Falciani Cheng Fang L. Gesztelyi

White (mutation)

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Citations (4)

A Nap- és csillagaktivitás a fotoszférától a koronáig = Solar and stellar activity from the photosphere to the corona

L. Gesztelyi Zs. Kõvári Katalin Oláh

A Nap aktivitasi jelensegek 3-dimenzios rekonstrukciojat vegeztuk el, űreszkozok eszleleseit modellezessel kombinalva. Kimutattuk, hogy (1) a konvektiv zonaban levő orvenyek a felszallo magneses fluxuscsovek deformaciojanak legfőbb okozoi; (2) a nyirott magneses terek disszipaciojan alapulo korona fűtesi modellek jobb egyezest mutatnak az eszlelesekből levont skalazasi szabalyokkal, mint az elektromagneses hullamok disszipaciojan alapulo modellek; 3) a feher flerek eseteben a koronaban jelentősen magasabb a gaznyomas, mint az azonos energiat felszabadito, de feher fenyű emissziot nem produkalo flerekben; (4) az első eszlelesi bizonyitekot szolgaltattuk a koronalyukak hatara menten folytonos magneses atkotődesre; (5) korona kitoresekben kulonboző modellek kombinalt, egymast segitő műkodese vezet aktivitashoz. Tovabba, uttorő munkat vegeztunk a magneses helicitas eszlelesekből valo meghatarozasara a koronaban es korona kitoresek soran kidobott interplanetaris magneses felhőkben, az első kvantitativ bizonyitekot szolgaltatvan fizikai kapcsolatukra. A csillagaktivitas teren sikerult megvalositani a legtobb celkitűzesunket. Tobb vizsgalatot vegeztunk a csillagok aktivitasara vonatkozoan hosszu időskalaju fotometriai es spektroszkopiai mereseket felhasznalva. Megerősitettuk a csillagokra kapott legrovidebb ciklushosszakat es osszefuggesuket a rotacios periodussal. Tobb aktiv csillagon mutattunk ki differencialis rotaciot Doppler lekepezes es fotometriai adatok felhasznalasaval (UZ Lib, zeta And, LQ Hya, IL Hya). Reszletesen vizsgaltuk tobb csillagon az aktiv hosszusagok helyzetet (IM Peg, UZ Lib, FK Com). | In solar studies we carried out 3-D reconstruction of solar events based on multi-wavelength space-born data combined with modelling. We have shown, that (1) in the convective zone emerging flux tubes are deformed mainly by huge vortices; (2) coronal heating models based on dissipation of stressed magnetic fields were in better agreement with the scaling laws deduced from observations than the models based on MHD wave dissipation; (3) white-light flares have higher coronal pressure than flares of the same energy, but having no white-light emission; (4) the first observational evidence for continuous magnetic reconnection along coronal hole boundaries; (5) in coronal mass ejections (CMEs) a combination of different models lead to eruption. Furthermore, we have done pioneering work on deducing magnetic helicity from observations both in the solar corona and in interplanetary magnetic clouds (MCs), which are ejected in CMEs, providing the first quantitative evidence for the direct corrrespondence between CMEs and MCs. In active star studies, we succesfully realised most of our goals. We carried our several studies on stellar activity using long-term spectroscopic and photometric observational data. We confirmed the shortest cycle lengths of stars and their correlation with the stars' rotational periods. Differential rotation was revelaed on several stars from Doppler maps and photometric data (UZ Lib, zeta And, LQ Hya, IL Hya). We studied the location of the active longitudes on IM Peg, UZ Lib and FK Com in details.

Photosphere

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White-light flare of 26 July 1981.

L. Gesztelyi M. Karlický F. Fárník O. Gerlei B. Valníček

Flare

White (mutation)

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Preflare activity of solar prominences

Solar Physics (1984)

G. Simon N. Mein P. Mein L. Gesztelyi

Solar prominence

10.1007/bf02270844

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Citations (19)

Sunspot proper motions in connection with the white-light flare of 25 April 1984

Advances in Space Research (1986)

L. Gesztelyi B. Kálmán

Sunspot

Flare

Solar flare

Nanoflares

10.1016/0273-1177(86)90107-9

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Citations (13)

The development of activity in Hale region 17098 (28 August - 8 September 1980).

L. Gesztelyi L. Kondás

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Consecutive homologous flares and their relation to sunspot motions

Advances in Space Research (1984)

L. Gesztelyi

Sunspot

Polarity (international relations)

Flare

Spots

Line (geometry)

10.1016/0273-1177(84)90152-2

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Citations (9)

A Nap és csillagdinamók éves időskálájú változásai = The yearly time-scale variability of the solar and stellar dynamos

Katalin Oláh Emese Zelmíra Forgácsné Dajka J. Jurcsik Zs. Kõvári B. Szeidl

A csillagaktivitas motorja a magneses dinamo, mely a differencialis rotacio es a konvektiv burok kovetkezmenye, es tobb időskalan is ciklikussagot mutat. A Napon rovidebb, 1-2 eves periodicitasokat talaltunk kulonboző aktivitasi indikatorokban. Kimutattuk, hogy a Nap hosszu, Gleissberg ciklusa az utobbi 500 evben folytonosan valtozik. 20 aktiv csillag ~20-50 ev hosszu adatsorat egy uj modszerrel analizalva azt talaltuk, hogy a ciklusok altalaban tobbszorosek es az időben valtoznak. Tobb aktiv csillag felszinen spektroszkopiai modszerekkel - Doppler lekepezes - differencialis rotaciot mutattunk ki, illetve csillagfelszinen meridionalis aramlasokat is talaltunk. Kidolgoztuk es alkalmaztuk a torzult feluletű csillagok Doppler lekepezeset. Kidolgoztunk egy uj modellt a koronakitoreseknek a napkoronaban valo fejlődesere. A koronakitoresek tagulo magneses ``buborekok'', es a Nap koronaja tele van kulonfele orientacioju magneses terekkel, es a koronakitoresek kolcsonhatnak es magnesesen atkotődnek, ha ellentetes iranyu magneses erővonalakkal talalkoznak tagulasuk soran. A fel nap koruli periodussal pulzalo RR Lyr csillagok koreben nagyszamu mereseink szerint a pulzaciojuk amplitudojat es fazisat valtoztato csillagok aranya lenyegesen tobb, mint amit az irodalombol ismerunk. A legrovidebb Blazhko-periodust a mi mereseinkből ismerjuk. A jelenseg okakent felmerult a magneses dinamo is, bar az egyeb megkozelitesek jelenleg megalapozottabbnak tűnnek. | The driving force of stellar activity is the magnetic dynamo resulting from the differential rotation and convective envelopes of stars, showing cycles on several timescales. In the Sun we found shorter, 1-2 years periodicities in different activity indicators. We demonstrated that the long, Gleissberg cycle of the Sun is continuously changing during the last 500 years. Using a new approach we studied the datasets of 20 stars and found that the cycles are generally multiple and variable. On the surface of a few active stars using spectroscopic methods - Doppler imaging - we found differential rotation and meridional flows. We constructed and applied a Doppler imaging method for non-spherical stellar surfaces. We prepared a model for the development of the mass ejections in the solar corona. The coronal mass ejections are expanding magnetic 'bubbles', the solar corona is full of magnetic fields of different orientations, and the coronal mass ejections counteract and magnetically reconnect when they meet magnetic field lines of different polarities during their expansion. According to our vast number of measurements, among the RR Lyrae star which pulsate around half day period, the number of objects whose amplitudes and phases are changing, is much higher than is known from the literature. The shortest Blazhko-period is revealed from our measurements. As cause of this phenomenon the magnetic dynamo raised up, but at present other approaches have firmer grounds.

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Homologous and homologous like microwave solar radio burst

Revista Mexicana de Astronomía y Astrofísica (1990)

Rafael Trevisan H. S. Sawant B. Kálmán L. Gesztelyi

Solar radio

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