Long duration thermal hard X-ray sources observed in two eruptive flares

We present observations of two eruptive flares on 17 of December 2006 (C1.9) and 19 of May 2007 (B9.7) which had good coverage with both Hinode and RHESSI. In these flares we see a long lived, gradual thermal hard X-ray source of low emission measure and, relative to the loops observed with GOES and XRT, high temperature. The lack of a non-thermal hard X-ray component and impulsive behaviour is inconsistent with electron beam driven chromospheric evaporation

Granular-Scale Elementary Flux Emergence Episodes in a Solar Active Region

We analyze data from Hinode spacecraft taken over two 54-minute periods during the emergence of AR 11024. We focus on small-scale portions within the observed solar active region and discover the appearance of very distinctive small-scale and short-lived dark features in Ca II H chromospheric filtergrams and Stokes I images. The features appear in regions with close-to-zero longitudinal magnetic field, and are observed to increase in length before they eventually disappear. Energy release in the low chromospheric line is detected while the dark features are fading. In time series of magnetograms a diverging bipolar configuration is observed accompanying the appearance of the dark features and the brightenings. The observed phenomena are explained as evidencing elementary flux emergence in the solar atmosphere, i.e small-scale arch filament systems rising up from the photosphere to the lower chromosphere with a length scale of a few solar granules. Brightenings are explained as being the signatures of chromospheric heating triggered by reconnection of the rising loops (once they reached chromospheric heights) with pre-existing magnetic fields as well as to reconnection/cancellation events in U-loop segments of emerging serpentine fields. We study the temporal evolution and dynamics of the events and compare them with the emergence of magnetic loops detected in quiet sun regions and serpentine flux emergence signatures in active regions. Incorporating the novel features of granular-scale flux emergence presented in this study we advance the scenario for serpentine flux emergence.Comment: 24 pages, 9 figures. Accepted for publication in Solar Physic

A slow coronal mass ejection with rising X-ray source

An eruptive event, which occurred on 16th April 2002, is discussed. Using images from the Transition Region and Coronal Explorer ( TRACE) at 195 angstrom, we observe a lifting flux rope which gives rise to a slow coronal mass ejection ( CME). There are supporting velocity observations from the Coronal Diagnostic Spectrometer ( CDS) on the Solar and Heliospheric Observatory ( SOHO), which illustrate the helical nature of the structure. Additionally a rising coronal hard X- ray source, which is observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager ( RHESSI), is shown to follow the flux rope with a speed of similar to 60 km s(-1). It is also sampled by the CDS slit, although it has no signature in the Fe XIX band. Following the passage of this source, there is evidence from the CDS for down- flowing ( cooling) material along newly reconnected loops through Doppler velocity observations, combined with magnetic field modeling. Later, a slow CME is observed with the Large Angle and Spectroscopic Coronagraph ( LASCO). We combine a height- time profile of the flux rope at lower altitudes with the slow CME. The rising flux rope speeds up by a factor of 1.7 at the start of the impulsive energy release and goes through further acceleration before reaching 1.5 solar radii. These observations support classical CME scenarios in which the eruption of a filament precedes flaring activity. Cusped flare loops are observed following the erupting flux rope and their altitude increases with time. In addition we find RHESSI sources both below and above the probable location of the reconnection region

An investigation of the sources of Earth-directed solar wind during Carrington Rotation 2053

In this work we analyze multiple sources of solar wind through a full Carrington Rotation (CR 2053) by analyzing the solar data through spectroscopic observations of the plasma upflow regions and the in situ data of the wind itself. Following earlier authors, we link solar and in situ observations by a combination of ballistic backmapping and potential-field source-surface modeling. We find three sources of fast solar wind that are low-latitude coronal holes. The coronal holes do not produce a steady fast wind, but rather a wind with rapid fluctuations. The coronal spectroscopic data from Hinode's Extreme Ultraviolet Imaging Spectrometer show a mixture of upflow and downflow regions highlighting the complexity of the coronal hole, with the upflows being dominant. There is a mix of open and multi-scale closed magnetic fields in this region whose (interchange) reconnections are consistent with the up- and downflows they generate being viewed through an optically thin corona, and with the strahl directions and freeze-in temperatures found in in situ data. At the boundary of slow and fast wind streams there are three short periods of enhanced-velocity solar wind, which we term intermediate based on their in situ characteristics. These are related to active regions that are located beside coronal holes. The active regions have different magnetic configurations, from bipolar through tripolar to quadrupolar, and we discuss the mechanisms to produce this intermediate wind, and the important role that the open field of coronal holes adjacent to closed-field active regions plays in the process

Signatures of Interchange Reconnection: STEREO, ACE and Hinode Observations Combined

Combining STEREO, ACE and Hinode observations has presented an opportunity to follow a filament eruption and coronal mass ejection (CME) on the 17th of October 2007 from an active region (AR) inside a coronal hole (CH) into the heliosphere. This particular combination of `open' and closed magnetic topologies provides an ideal scenario for interchange reconnection to take place. With Hinode and STEREO data we were able to identify the emergence time and type of structure seen in the in-situ data four days later. On the 21st, ACE observed in-situ the passage of an ICME with `open' magnetic topology. The magnetic field configuration of the source, a mature AR located inside an equatorial CH, has important implications for the solar and interplanetary signatures of the eruption. We interpret the formation of an `anemone' structure of the erupting AR and the passage in-situ of the ICME being disconnected at one leg, as manifested by uni-directional suprathermal electron flux in the ICME, to be a direct result of interchange reconnection between closed loops of the CME originating from the AR and `open' field lines of the surrounding CH.Comment: 13 pages, 13 figures, accepted Annales Geophysica

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

A Nap aktivitási jelenségek 3-dimenziós rekonstrukcióját végeztük el, űreszközök észleléseit modellezéssel kombinálva. Kimutattuk, hogy (1) a konvektív zónában levő örvények a felszálló mágneses fluxuscsövek deformációjának legfőbb okozói; (2) a nyírott mágneses terek disszipációján alapuló korona fűtési modellek jobb egyezést mutatnak az észlelésekből levont skálázási szabályokkal, mint az elektromágneses hullámok disszipációján alapuló modellek; 3) a fehér flerek esetében a koronában jelentősen magasabb a gáznyomás, mint az azonos energiát felszabadító, de fehér fényű emissziót nem produkáló flerekben; (4) az első észlelési bizonyítékot szolgáltattuk a koronalyukak határa mentén folytonos mágneses átkötődésre; (5) korona kitörésekben különböző modellek kombinált, egymást segítő működése vezet aktivitáshoz. Továbbá, úttörő munkát végeztünk a mágneses helicitás észlelésekből való meghatározására a koronában és korona kitörések során kidobott interplanetáris mágneses felhőkben, az első kvantitatív bizonyítékot szolgáltatván fizikai kapcsolatukra. A csillagaktivitás terén sikerült megvalósítani a legtöbb célkitűzésünket. Több vizsgálatot végeztünk a csillagok aktivitására vonatkozóan hosszú időskálájú fotometriai és spektroszkópiai méréseket felhasználva. Megerősítettük a csillagokra kapott legrövidebb ciklushosszakat és összefüggésüket a rotációs periódussal. Több aktív csillagon mutattunk ki differenciális rotációt Doppler leképezés és fotometriai adatok felhasználásával (UZ Lib, zeta And, LQ Hya, IL Hya). Részletesen vizsgáltuk több csillagon az aktív hosszúságok helyzetét (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