Kneer, Franz

[["dc.bibliographiccitation.firstpage","373"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","378"],["dc.bibliographiccitation.volume","436"],["dc.contributor.author","Puschmann, K. G."],["dc.contributor.author","Kneer, F."],["dc.date.accessioned","2018-11-07T10:24:08Z"],["dc.date.available","2018-11-07T10:24:08Z"],["dc.date.issued","2005"],["dc.description.abstract","Our work is an attempt to fulfil one of the aims of astronomical imaging, that is, to obtain information at high angular resolution. Stars as point sources can be represented by Dirac delta-functions whose Fourier transforms contain information about the position and the (integrated) intensity at all angular frequencies. Thus, we can deconvolve unresolved images of star fields even at angular distances smaller than the diffraction limit of the telescope with which the observations are performed. We give an example of reconstruction of the image of two stars with an angular separation of a factor 2.5 less than alpha(Ra) = 1.22 x lambda/D. However, we find that super-resolution is feasible only for point sources. For extended objects the information about intensity fluctuations at angular frequencies u > u(max) = D/lambda = 1/alpha(min) is irretrievably lost. We discuss the impossibility of super-resolution for the Sun using a numerically simulated image of solar granulation. However, one can enhance the contrast of solar images, though without increasing angular resolution beyond the diffraction limit."],["dc.identifier.doi","10.1051/0004-6361:20042320"],["dc.identifier.fs","38260"],["dc.identifier.isi","000229265500035"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9858"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/42601"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","E D P Sciences"],["dc.relation.issn","0004-6361"],["dc.relation.orgunit","Fakultät für Physik"],["dc.title","On super-resolution in astronomical imaging"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1151"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","1158"],["dc.bibliographiccitation.volume","451"],["dc.contributor.author","Puschmann, K. G."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Seelemann, T."],["dc.contributor.author","Wittmann, A. D."],["dc.date.accessioned","2019-07-09T11:54:35Z"],["dc.date.available","2019-07-09T11:54:35Z"],["dc.date.issued","2006"],["dc.description.abstract","Studies of small-scale dynamics and magnetic fields in the solar atmosphere require spectroscopy and polarimetry with high spatial resolution. For this purpose, spectrometers based on Fabry-Pérot interferometers (FPIs) have advantages over slit spectrographs. They possess a high throughput and allow fast two-dimensional, narrow-band imaging and image reconstruction of the data. In the present contribution we describe an upgrade, essentially renewal, of the Göttingen FPI spectrometer achieved during the first half of 2005. A new etalon from IC Optical Systems Ltd. (formerly Queensgate), England, with 70mm free aperture for high spectral resolution has been mounted. New CCD detectors from LaVision GmbH (Göttingen) with powerful computer hard- and software were implemented. We consider the product of signal-to-noise ratio, frame rate, and field of view as a measure of the efficiency. At low light levels, e.g. in narrow-band speckle applications, this product has increased by a factor ∼60 compared to the old system. In addition, several spectral regions can now be scanned quasi-simultaneously. We present first results obtained with the upgraded spectrometer. The efforts are undertaken to provide an up-to-date post-focus instrument for the new German 1.5m GREGOR solar telescope presently under construction at the Observatorio del Teide on Tenerife."],["dc.identifier.doi","10.1051/0004-6361:20054487"],["dc.identifier.fs","45044"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9384"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/60684"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","1432-0746"],["dc.relation.orgunit","Fakultät für Physik"],["dc.rights","Goescholar"],["dc.rights.access","openAccess"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","The new Göttingen Fabry-Pérot spectrometer for two-dimensional observations of the Sun"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","L51"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","L54"],["dc.bibliographiccitation.volume","472"],["dc.contributor.author","Sánchez-Andrade Nuño, B."],["dc.contributor.author","Centeno, R."],["dc.contributor.author","Puschmann, K. G."],["dc.contributor.author","Trujillo Bueno, J."],["dc.contributor.author","Blanco Rodríguez, J."],["dc.contributor.author","Kneer, F."],["dc.date.accessioned","2019-07-09T11:54:35Z"],["dc.date.available","2019-07-09T11:54:35Z"],["dc.date.issued","2007"],["dc.description.abstract","Aims. Off-the-limb observations with high spatial and spectral resolution will help us understand the physical properties of spicules in the solar chromosphere. Methods. Spectropolarimetric observations of spicules in the He i 10 830 Å multiplet were obtained with the Tenerife Infrared Polarimeter on the German Vacuum Tower Telescope at the Observatorio del Teide (Tenerife, Spain). The analysis shows the variation of the off-limb emission profiles as a function of the distance to the visible solar limb. The ratio between the intensities of the blue and the red components of this triplet (R = Iblue/Ired) is an observational signature of the optical thickness along the light path, which is related to the intensity of the coronal irradiation. Results. We present observations of the intensity profiles of spicules above a quiet Sun region. The observable R as a function of the distance to the visible limb is also given. We have compared our observational results to the intensity ratio obtained from detailed radiative transfer calculations in semi-empirical models of the solar atmosphere assuming spherical geometry. The agreement is purely qualitative. We argue that future models of the solar chromosphere and transition region should account for the observational constraints presented here."],["dc.identifier.doi","10.1051/0004-6361:20077936"],["dc.identifier.fs","297858"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9401"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/60687"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","1432-0746"],["dc.relation.orgunit","Fakultät für Physik"],["dc.rights","Goescholar"],["dc.rights.access","openAccess"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Spicule emission profiles observed in He I 10 830 Å"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","880"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.lastpage","893"],["dc.bibliographiccitation.volume","333"],["dc.contributor.author","Puschmann, K. G."],["dc.contributor.author","Denker, C."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Al Erdogan, N."],["dc.contributor.author","Balthasar, H."],["dc.contributor.author","Bauer, S. M."],["dc.contributor.author","Beck, C."],["dc.contributor.author","Gonzalez, N. Bello"],["dc.contributor.author","Collados, M."],["dc.contributor.author","Hahn, T."],["dc.contributor.author","Hirzberger, J."],["dc.contributor.author","Hofmann, Albrecht W."],["dc.contributor.author","Louis, R. E."],["dc.contributor.author","Nicklas, H."],["dc.contributor.author","Okunev, O."],["dc.contributor.author","Martinez Pillet, V."],["dc.contributor.author","Popow, E."],["dc.contributor.author","Seelemann, T."],["dc.contributor.author","Volkmer, R."],["dc.contributor.author","Wittmann, A. D."],["dc.contributor.author","Woche, M."],["dc.date.accessioned","2018-11-07T09:04:01Z"],["dc.date.available","2018-11-07T09:04:01Z"],["dc.date.issued","2012"],["dc.description.abstract","The GREGOR Fabry-Perot Interferometer (GFPI) is one of three first-light instruments of the German 1.5-meter GREGOR solar telescope at the Observatorio del Teide, Tenerife, Spain. The GFPI uses two tunable etalons in collimated mounting. Thanks to its large-format, high-cadence CCD detectors with sophisticated computer hard- and software it is capable of scanning spectral lines with a cadence that is sufficient to capture the dynamic evolution of the solar atmosphere. The field-of-view (FOV) of 50 ' x38 ' is well suited for quiet Sun and sunspot observations. However, in the vector spectropolarimetric mode the FOV reduces to 25 ' x38 '. The spectral coverage in the spectroscopic mode extends from 530-860 nm with a theoretical spectral resolution of R approximate to 250 000, whereas in the vector spectropolarimetric mode the wavelength range is at present limited to 580-660 nm. The combination of fast narrow-band imaging and post-factum image restoration has the potential for discovery science concerning the dynamic Sun and its magnetic field at spatial scales down to similar to 50 km on the solar surface. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim"],["dc.identifier.doi","10.1002/asna.201211734"],["dc.identifier.isi","000310799500015"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/25018"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.relation.issn","0004-6337"],["dc.title","The GREGOR Fabry-Perot Interferometer"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.subtype","letter_note"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","796"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.lastpage","809"],["dc.bibliographiccitation.volume","333"],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","von der Luehe, O."],["dc.contributor.author","Volkmer, R."],["dc.contributor.author","Denker, C."],["dc.contributor.author","Solanki, Parth K."],["dc.contributor.author","Balthasar, H."],["dc.contributor.author","Gonzalez, N. Bello"],["dc.contributor.author","Berkefeld, Th."],["dc.contributor.author","Collados, M."],["dc.contributor.author","Fischer, A."],["dc.contributor.author","Halbgewachs, C."],["dc.contributor.author","Heidecke, F."],["dc.contributor.author","Hofmann, Albrecht W."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Lagg, A."],["dc.contributor.author","Nicklas, H."],["dc.contributor.author","Popow, E."],["dc.contributor.author","Puschmann, K. G."],["dc.contributor.author","Schmidt, D."],["dc.contributor.author","Sigwarth, M."],["dc.contributor.author","Sobotka, M."],["dc.contributor.author","Soltau, D."],["dc.contributor.author","Staude, J."],["dc.contributor.author","Strassmeier, K. G."],["dc.contributor.author","Waldmann, T."],["dc.date.accessioned","2018-11-07T09:03:59Z"],["dc.date.available","2018-11-07T09:03:59Z"],["dc.date.issued","2012"],["dc.description.abstract","The 1.5 m telescope GREGOR opens a new window to the understanding of solar small-scale magnetism. The first light instrumentation includes the Gregor Fabry Perot Interferometer (GFPI), a filter spectro-polarimeter for the visible wavelength range, the GRating Infrared Spectro-polarimeter (GRIS) and the Broad-Band Imager (BBI). The excellent performance of the first two instruments has already been demonstrated at the Vacuum Tower Telescope. GREGOR is Europes largest solar telescope and number 3 in the world. Its all-reflective Gregory design provides a large wavelength coverage from the near UV up to at least 5 microns. The field of view has a diameter of 150 '. GREGOR is equipped with a high-order adaptive optics system, with a subaperture size of 10 cm, and a deformable mirror with 256 actuators. The science goals are focused on, but not limited to, solar magnetism. GREGOR allows us to measure the emergence and disappearance of magnetic flux at the solar surface at spatial scales well below 100 km. Thanks to its spectro-polarimetric capabilities, GREGOR will measure the interaction between the plasma flows, different kinds of waves, and the magnetic field. This will foster our understanding of the processes that heat the chromosphere and the outer layers of the solar atmosphere. Observations of the surface magnetic field at very small spatial scales will shed light on the variability of the solar brightness. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim"],["dc.identifier.doi","10.1002/asna.201211725"],["dc.identifier.isi","000310799500005"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/25015"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","0004-6337"],["dc.title","The 1.5 meter solar telescope GREGOR"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","letter_note"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","205"],["dc.bibliographiccitation.issue","3-4"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.lastpage","207"],["dc.bibliographiccitation.volume","326"],["dc.contributor.author","Okunev, O."],["dc.contributor.author","Cerdena, I. D."],["dc.contributor.author","Puschmann, K. G."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Almeida, J. S."],["dc.date.accessioned","2018-11-07T08:34:37Z"],["dc.date.available","2018-11-07T08:34:37Z"],["dc.date.issued","2005"],["dc.description.abstract","Quiet Sun magnetic fields in the intemetwork are almost ubiquitous. Simultaneous observations in infra-red and visible lines and high spatial resolution (< 0.5\") data in visible lines show that their field strengths range from below few hundred Gauss to kilo-Gauss. Most of the flux is contained in small-scale, strong-field features located mainly in intergranular lanes. The average unsigned flux density exceeds 20 Gauss. The new detections are confirmed by recent quiet Sun observations in the G band. The generation of the strong fields in the intemetwork, which may be due to a local dynamo, poses a challenging problem. - Polar faculae (PFe) are small-scale magnetic features at the polar caps of the Sun. They take part in the solar cycle and are thus likely to be rooted deeply in the solar interior. They are the result of the global dynamo at the solar poles. PFe also possess kilo-Gauss magnetic fields which have the same polarity as the global magnetic field. The r (o) over cap le of quiet Sun magnetic field structures and of PFe for the dynamics of the corona and for the solar wind are addressed."],["dc.identifier.doi","10.1002/asna.200410377"],["dc.identifier.isi","000228414900009"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/17858"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.relation.issn","1521-3994"],["dc.relation.issn","0004-6337"],["dc.title","Quiet sun magnetic fields vs. polar faculae - local vs. global dynamo?"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","317"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","327"],["dc.bibliographiccitation.volume","434"],["dc.contributor.author","Gonzalez, N. Bello"],["dc.contributor.author","Okunev, O."],["dc.contributor.author","Cerdena, I. D."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Puschmann, K. G."],["dc.date.accessioned","2018-11-07T11:09:25Z"],["dc.date.available","2018-11-07T11:09:25Z"],["dc.date.issued","2005"],["dc.description.abstract","We present two-dimensional high-spatial-resolution spectropolarimetric observations of sunspot penumbrae. They were obtained in April 2002 and May 2003 with the \"Gottingen\" Fabry-Perot spectrometer at the Vacuum Tower Telescope at the Observatorio del Teide ( Tenerife). Speckle methods were applied for image reconstruction which resulted in a spatial resolution of 0.'' 5 in the magnetograms of the penumbrae. We analysed Stokes I and V profiles of the Fe II 6149 angstrom line, which exhibits no instrumental Stokes Q/U -> V crosstalk, and of the Fe I line pair at 6302 angstrom. The main results are the following: 1) on scales larger than 0.'' 5, the intensity pattern of penumbrae stays the same in the continuum and core images of the 6301.5 angstrom line, which stem from 0 km and 300 km (above tau(5) = 1), respectively. Yet at scales of 0.'' 5 and smaller the pattern in the two spectral features is clearly different. 2) On the limb side of sunspots the Evershed flow is carried by dark filaments and on the centre side by bright features and their somewhat weakened tails. We explain this with a picture in which the velocity of hot rising gas is best seen on the centre side, while on the limb side the horizontal outward and possibly downward flows are seen when the gas has cooled down. 3) The un-combed structure of the magnetic field is confirmed. On the limb side, the more horizontal fields coincide with dark fibrils or with diffuse intensity structures. Generally, the more horizontal fields are located at the positions of strong outflows. 4) Strong line-of-sight components of the magnetic fields are not found in bright filaments but in dark structures, somewhat displaced from the darkest parts. Their positions do not coincide with those of the strongest velocity fields. In general, our results are compatible with the picture of low lying flow channels coincident with the horizontal magnetic field, or possibly emerging and diving down into sub-photospheric layers, like a \"sea serpent\". Some further dynamic phenomena are discussed, which demonstrate the richness of processes in penumbrae, and reveal unexpected properties."],["dc.identifier.doi","10.1051/0004-6361:20042001"],["dc.identifier.fs","38062"],["dc.identifier.isi","000228097300031"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9860"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/53004"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Edp Sciences S A"],["dc.relation.issn","0004-6361"],["dc.relation.orgunit","Fakultät für Physik"],["dc.title","Polarimetry of sunspot penumbrae with high spatial resolution"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","251"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","259"],["dc.bibliographiccitation.volume","474"],["dc.contributor.author","Blanco Rodríguez, J."],["dc.contributor.author","Okunev, O. V."],["dc.contributor.author","Puschmann, K. G."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Sánchez-Andrade Nuño, B."],["dc.date.accessioned","2019-07-09T11:54:59Z"],["dc.date.available","2019-07-09T11:54:59Z"],["dc.date.issued","2007"],["dc.description.abstract","Context.Faculae at the poles of the Sun, or polar faculae (PFe), take part in the solar magnetic cycle. Their occurrence maximum is shifted by 5-6 years with respect to the sunspot cycle. PFe are stable phenomena, with lifetimes of several hours to days, and harbour magnetic fields of kilo-Gauss strength. Yet their role for the global magnetic field at the solar poles is unknown. Aims.To contribute to the knowledge of the physical properties of PFe and to the understanding of their role in the global magnetism of the Sun. Methods.PFe were observed on 21-24 August 2005 with the Vacuum Tower Telescope at the Observatorio del Teide. The \"Göttingen\" Fabry-Perot spectrometer was used with a Stokes V polarimeter to scan the Fe I 6173 Å line (Landé factor g = 2.5) and the H$\\alpha$ line in two-dimensional fields of view (FOVs). A large observational coverage of the polar caps was obtained. The data were analysed with speckle methods. Magnetic field strengths were determined with the weak field approximation, with the approximation of the strong field regime, and with the centre of gravity (COG) method. Velocities were measured with the COG method and from the zero-crossing of the Stokes V profiles. Results.PFe show a decrease of the continuum and broadband intensity contrast towards the disc centre and no decrease of contrast towards the limb, similar to as faculae in active regions near the equator. Extrapolating from the observed FOVs to the total areas of PF occurrence around the solar poles, we find 4 120 PFe in the northern polar cap and, asymmetrically to this number, 1 250 PFe near the south pole. The total area coverages by PFe are ~7.6$\\times08 km2 and ~3.4$\\times08 km2 near the solar north and south poles, respectively. Some of the PFe exhibit magnetic polarities opposite to the global polarity at the time of observation. The resulting total magnetic fluxes in PFe fall short by an order of magnitude from those found in the literature for the fluxes at the polar caps. This also holds if we include magnetic structures which are not related to brightenings. We conclude that with the present spatial resolution of ./noch-last.sh \\farcs4{-}0\\farcs5$ (FWHM), PFe represent the \"large-scale\" end of a distribution of unipolar strands near the solar poles. The velocities in PFe show amplitudes of 2 km s-1, with systematic up-flows in the Stokes I profile, but no average velocity measured in the V zero-crossings."],["dc.identifier.doi","10.1051/0004-6361:20077739"],["dc.identifier.fs","297812"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9932"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/60773"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","1432-0746"],["dc.relation.orgunit","Fakultät für Physik"],["dc.rights","Goescholar"],["dc.rights.access","openAccess"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","On the properties of faculae at the poles of the Sun"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","577"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","587"],["dc.bibliographiccitation.volume","486"],["dc.contributor.author","Sánchez-Andrade Nuño, B."],["dc.contributor.author","Bello González, N."],["dc.contributor.author","Blanco Rodríguez, J."],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Puschmann, K. G."],["dc.date.accessioned","2019-07-09T11:55:00Z"],["dc.date.available","2019-07-09T11:55:00Z"],["dc.date.issued","2008-08-01"],["dc.description.abstract","Context. We study the chromosphere of an active region of the Sun in the H$\\alpha$ line. Aims. The development of new instrumentation and new methods of data analysis allows to scrutinize the dynamics of the solar chromosphere with high spatial, spectral, and temporal resolution. The observations we present shed light on some magneto-dynamic processes occurring above an active region in the chromosphere. Methods. We took a time series of 55 min in H$\\alpha$ from AR 10875 at $\\vartheta\\approx36\\degr$. We used the \"Göttingen\" Fabry-Perot spectrometer at the Vacuum Tower Telescope, Observatorio del Teide/Tenerife, to obtain two-dimensional spectrograms in H$\\alpha$. Adaptive optics and image reconstruction yielded a spatial resolution better than 0$\\farcs throughout the time sequence. From the wealth of structures, we selected areas of interest to study further, in detail, some ongoing processes. Results. A small straight surge developed aside of a pore with upward phase speed of 100 km s-1 and line-of-sight (LOS) velocity of 15 km s-1. The surge retreated rapidly with LOS velocity of 45 km s-1 at its mouth. It underwent a rebound and fell back again. Two sympathetic mini-flares were observed that lasted only approximately 40 s, but showed strong H$\\alpha$ emission. We found magnetoacoustic waves in long fibrils as mainly short wave trains, short packets or pulses, i.e., solitary waves consisting of small (1´´-2´´) blobs. They start at either end of the fibrils and travel with phase speeds of 12-14 km s-1, i.e., close to the tube speed and approximately the sound velocity for sufficiently large magnetic field strengths. Some waves speed up to reach velocities of the order of 30 km s-1. This is much lower than the expected Alfvén velocity of $\\ge00 km s-1 for reasonable magnetic field strengths and mass densities. We suggest that slow waves are not purely longitudinal, but possess gas velocities perpendicular to the direction of propagation of few km s-1. Also, fast waves travel along sinuous lines suggesting entangled magnetic fields. They spread out along the direction of propagation in the course of their evolution and often vanish. We discuss the implications."],["dc.identifier.doi","10.1051/0004-6361:20079231"],["dc.identifier.fs","513433"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9946"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/60776"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","1432-0746"],["dc.relation.orgunit","Fakultät für Physik"],["dc.rights","Goescholar"],["dc.rights.access","openAccess"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Fast events and waves in an active region of the Sun observed in Hα with high spatial resolution"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Astronomische Nachrichten"],["dc.bibliographiccitation.volume","324"],["dc.contributor.author","Kneer, F."],["dc.contributor.author","Al, N."],["dc.contributor.author","Hirzberger, J."],["dc.contributor.author","Nicklas, H."],["dc.contributor.author","Puschmann, K. G."],["dc.date.accessioned","2018-11-07T10:41:57Z"],["dc.date.available","2018-11-07T10:41:57Z"],["dc.date.issued","2003"],["dc.format.extent","302"],["dc.identifier.doi","10.1002/asna.200310102"],["dc.identifier.isi","000183506400009"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/46663"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.publisher.place","Weinheim"],["dc.relation.conference","Workshop on From the Gregory-Coude Telescope to GREGOR - A Development from Past to Future"],["dc.relation.eventlocation","GOTTINGEN UNIV, III PHYS INST, GOTTINGEN, GERMANY"],["dc.relation.issn","0004-6337"],["dc.title","A Fabry-Perot spectrometer for high-resolution observation of the Sun"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]