S. Koutchmy

X-Ray Jet Dynamics in a Polar Coronal Hole Region

New X-ray observations of the north polar region taken from the X-ray Telescope (XRT) of the Hinode spacecraft are used to analyze several time sequences showing small loop brightenings with a long ray above. We focus on the formation of the jet and discuss scenarios to explain the main features of the events: the relationship with the expected surface magnetism, the rapid and sudden radial motion, and possibly the heating, based on the assumption that the jet occurs above a null point of the coronal magnetic field. We conclude that 2-D reconnection models should be complemented in order to explain the observational details of these events and suggest that alternative scenarios may exist.

Prominence fine structure II: Diagnostics

A random-clustering model of prominence fine-structure has been applied to observations of prominence Hα spectra. The model yields an estimate of the number of unresolved elements that form an individual resolved feature, and sets limits on their velocity and Hα profile dispersions.

Formation of a White-Light Jet Within a Quadrupolar Magnetic Configuration

We analyze multi-wavelength and multi-viewpoint observations of a large-scale event viewed on 7 April 2011, originating from an active-region complex. The activity leads to a white-light jet being formed in the outer corona. The topology and evolution of the coronal structures were imaged in high resolution using the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). In addition, large field-of-view images of the corona were obtained using the Sun Watcher using Active Pixel System detector and Image Processing (SWAP) telescope onboard the PRoject for Onboard Autonomy (PROBA2) microsatellite, providing evidence for the connectivity of the coronal structures with outer coronal features that were imaged with the Large Angle Spectrometric Coronagraph (LASCO) C2 on the Solar and Heliospheric Observatory (SOHO). The data sets reveal an Eiffel-tower type jet configuration extending into a narrow jet in the outer corona. The event starts from the growth of a dark area in the central part of the structure. The darkening was also observed in projection on the disk by the Solar TErrestrial RElations Observatory-Ahead (STEREO-A) spacecraft from a different point of view. We assume that the dark volume in the corona descends from a coronal cavity of a flux rope that moved up higher in the corona but still failed to erupt. The quadrupolar magnetic configuration corresponds to a saddle-like shape of the dark volume and provides a possibility for the plasma to escape along the open field lines into the outer corona, forming the white-light jet.

Properties of Impulsive Events in a Polar Coronal Hole

Observations made at NSO/Sacramento Peak Observatory with the 16″ Coronagraph allow the analysis of fast impulsive events. Broad-band Hα filtergrams and CCD-spectra taken at 1 to 45 arcsec above the solar chromospheric-limb are used. A deep well-developed Coronal Hole was chosen above a Polar Region, during years of minimum of sunspot activity. We present a whole range of impulsive events observed there in 1988. They are tentatively analyzed using statistical methods and the results strongly suggest they could be the source of the fast wind. The recurrence of impulsive events is reported for the first time.

Limb Event Brightenings and Fast Ejection Using IRIS Mission Observations

The Interface Region Imaging Spectrograph (IRIS) of the recently commissioned NASA small explorer mission provides significantly more complete and higher resolution spectral coverage of the dynamical conditions inside the chromosphere and transition region (TR) than has been available ever before. High temporal, spatial (0.3″

About the foreshortening effect on sunspot umbral dots

0.3

THE INFRARED GRANULATION: OBSERVATIONS

) and spectral resolution observations from the ultraviolet IRIS spectra near the solar limb reveal high-energy limb event brightenings (LEBs) at low chromospheric heights at about 1xa0Mm above the limb. They can be characterized as explosive events producing jets. We selected two events showing spectra of a confined eruption just off or near the quiet-Sun limb, the jet part showing obvious moving material with short-duration large Doppler shifts in three directions that were identified as macrospicules on slit-jaw (SJ) images in Sixa0iv and Hexa0ii 304xa0Å. The events were analyzed from a sequence of very close rasters taken near the central meridian and the South Pole limb. We analyzed the processed SJ images and the simultaneously observed fast spectral sequences, which have large Doppler shifts, with a pair of redshifted elements together with a faster blueshifted element from almost the same position. Shifts correspond to velocities of up to 100kms−1

OBSERVATION OF GLOBAL 160-MIN INFRARED (DIFFERENTIAL) INTENSITY VARIATION OF THE SUN*

100~mbox{km},mbox{s}^{-1}

Photometrie photographique de la couronne solaire

in projection on the plane of the sky. Erupting spicules and macrospicules from these regions are visible in images taken before and after the spectra. The cool low first ionization potential (FIP) element simultaneous line emissions of the Mgxa0ii h and k resonance lines do not clearly show a similar signature because of optical thickness effects, but the Sixa0iv broadband SJ images do. The bidirectional plasma jets ejected from a small reconnection site are interpreted to be the result of coronal loop–loop interactions that lead to reconnection in nearby sites.

Jet phenomena above null points of the coronal magnetic field

Using high-resolution pictures of the core of a unipolar sunspot observed with several cos θ values, we studied the center limb effect on the form of the bright umbral dots. The ratio of the apparent sizes in radial and tangential direction do not show the foreshortening effect typically observed in granular structures.