Beuermann, Klaus Peter

[["dc.bibliographiccitation.firstpage","671"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","681"],["dc.bibliographiccitation.volume","451"],["dc.contributor.author","Euchner, F."],["dc.contributor.author","Jordan, S."],["dc.contributor.author","Beuermann, Klaus"],["dc.contributor.author","Reinsch, K."],["dc.contributor.author","Gansicke, B. T."],["dc.date.accessioned","2018-11-07T09:50:53Z"],["dc.date.available","2018-11-07T09:50:53Z"],["dc.date.issued","2006"],["dc.description.abstract","Aims. We analyse the magnetic field geometry of the magnetic DA white dwarf PG1015+014 with our Zeeman tomography method. Methods. This study is based on rotation-phase resolved optical flux and circular polarization spectra of PG1015+014 obtained with FORS1 at the ESO VLT. Our tomographic code makes use of an extensive database of pre-computed Zeeman spectra. The general approach has been described in Papers I and II of this series. Results. The surface field strength distributions for all rotational phases of PG1015+014 are characterised by a strong peak at 70 MG. A separate peak at 80MG is seen for about one third of the rotation cycle. Significant contributions to the Zeeman features arise from regions with field strengths between 50 and 90 MG. We obtain equally good simultaneous fits to the observations, collected in five phase bins, for two different field parametrizations: (i) a superposition of individually tilted and off-centred zonal multipole components; and (ii) a truncated multipole expansion up to degree l = 4 including all zonal and tesseral components. The magnetic fields generated by both parametrizations exhibit a similar global structure of the absolute surface field values, but differ considerably in the topology of the field lines. An effective photospheric temperature of T-eff = 10 000 +/- 1000 K was found. Conclusions. Remaining discrepancies between the observations and our best-fit models suggest that additional small-scale structure of the magnetic field exists which our field models are unable to cover due to the restricted number of free parameters."],["dc.identifier.doi","10.1051/0004-6361:20064840"],["dc.identifier.fs","45028"],["dc.identifier.isi","237272100027"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9385"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/35801"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Edp Sciences S A"],["dc.relation.issn","1432-0746"],["dc.relation.orgunit","Fakultät für Physik"],["dc.title","Zeeman tomography of magnetic white dwarfs - III. The 70-80 Megagauss magnetic field of PG1015+014"],["dc.title.original","9385"],["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","143"],["dc.bibliographiccitation.issue","1-2"],["dc.bibliographiccitation.journal","New Astronomy Reviews"],["dc.bibliographiccitation.lastpage","148"],["dc.bibliographiccitation.volume","44"],["dc.contributor.author","Gansicke, B. T."],["dc.contributor.author","van Teeseling, A."],["dc.contributor.author","Beuermann, Klaus"],["dc.contributor.author","Reinsch, K."],["dc.date.accessioned","2018-11-07T11:25:18Z"],["dc.date.available","2018-11-07T11:25:18Z"],["dc.date.issued","2000"],["dc.description.abstract","Recent observational results on supersoft X-ray binaries are reviewed, with emphasis on the galactic source QR And and on the enigmatic LMC source RX J0439.8-6809. (C) 2000 Elsevier Science B.V. All rights reserved."],["dc.identifier.doi","10.1016/S1387-6473(00)00028-2"],["dc.identifier.isi","000090017800026"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/56592"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Sci Ltd"],["dc.publisher.place","Oxford"],["dc.relation.conference","Cataclysmic Variables: a 60th Birthday Symposium in Honour of Brian Warner"],["dc.relation.eventlocation","OXFORD UNIV, OXFORD, ENGLAND"],["dc.relation.issn","1387-6473"],["dc.title","Supersoft X-ray binaries: an observational update"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","651"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","660"],["dc.bibliographiccitation.volume","442"],["dc.contributor.author","Euchner, F."],["dc.contributor.author","Reinsch, K."],["dc.contributor.author","Jordan, S."],["dc.contributor.author","Beuermann, Klaus"],["dc.contributor.author","Gansicke, B. T."],["dc.date.accessioned","2018-11-07T10:54:29Z"],["dc.date.available","2018-11-07T10:54:29Z"],["dc.date.issued","2005"],["dc.description.abstract","We report time-resolved optical flux and circular polarization spectroscopy of the magnetic DA white dwarf HE 1045- 0908 obtained with FORS1 at the ESO VLT. Considering published results, we estimate a likely rotational period of P-rot similar or equal to 2.7 h, but cannot exclude values as high as about 9 h. Our detailed Zeeman tomographic analysis reveals a field structure which is dominated by a quadrupole and contains additional dipole and octupole contributions, and which does not depend strongly on the assumed value of the period. A good fit to the Zeeman flux and polarization spectra is obtained if all field components are centred and inclinations of their magnetic axes with respect to each other are allowed for. The fit can be slightly improved if an offset from the centre of the star is included. The prevailing surface field strength is 16 MG, but values between 10 and similar to 75 MG do occur. We derive an effective photospheric temperature of HE 1045- 0908 of T-eff = 10 000 +/- 1000 K. The tomographic code makes use of an extensive database of pre-computed Zeeman spectra ( Paper I)."],["dc.identifier.doi","10.1051/0004-6361:20053038"],["dc.identifier.isi","232404400032"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9389"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/49572"],["dc.notes.intern","In goescholar not merged with http://resolver.sub.uni-goettingen.de/purl?gs-1/9853 but duplicate"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Edp Sciences S A"],["dc.relation.issn","1432-0746"],["dc.rights","Goescholar"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Zeeman tomography of magnetic white dwarfs - II. The quadrupole-dominated magnetic field of HE 1045-0908"],["dc.title.original","9389"],["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","L79"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","L82"],["dc.bibliographiccitation.volume","356"],["dc.contributor.author","Gansicke, B. T."],["dc.contributor.author","Fried, R. E."],["dc.contributor.author","Hagen, H. J."],["dc.contributor.author","Beuermann, Klaus"],["dc.contributor.author","Engels, D."],["dc.contributor.author","Hessman, Frederic V."],["dc.contributor.author","Nogami, D."],["dc.contributor.author","Reinsch, K."],["dc.date.accessioned","2018-11-07T10:37:35Z"],["dc.date.available","2018-11-07T10:37:35Z"],["dc.date.issued","2000"],["dc.description.abstract","We report on follow-up spectroscopy and photometry of the cataclysmic variable candidate HS 0907+1902 selected from the Hamburg Quasar Survey. B, V, and R photometry obtained during the first observed outburst of HS 0907+1902 (V approximate to 13) reveals deep eclipses (Delta V approximate to 2.1 - 2.8) and an orbital period P(orb) = 4.2 h with the eclipse depth decreasing to the red. The outburst eclipse profiles are symmetric, indicating an axisymmetrical brightness distribution in the accretion disc. We derive an inclination i approximate to 73 degrees - 79 degrees from the eclipse duration. The quiescent spectrum obtained with the Hobby-Eberly Telescope shows double peaked emission lines of H I, He I and Fe I,II and clearly identifies the system as a dwarf nova. Absorption features of the secondary star are detected at red wavelengths from which a spectral class M3 +/- 1.5 and a distance of d = 320 +/- 100 pc are derived."],["dc.identifier.isi","000087446700005"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/45601"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","0004-6361"],["dc.title","HS 0907+1902: a new 4.2 hr eclipsing dwarf nova"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","487"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","490"],["dc.bibliographiccitation.volume","381"],["dc.contributor.author","Beuermann, Klaus"],["dc.contributor.author","Reinsch, K."],["dc.date.accessioned","2018-11-07T10:32:46Z"],["dc.date.available","2018-11-07T10:32:46Z"],["dc.date.issued","2002"],["dc.description.abstract","We have investigated the nature of the magnetic white dwarf LP 790-29 = LHS 2293 by polarimetric monitoring, searching for short-term variability. No periodicity was found and we can exclude rotation periods between 4 s and 1.5 hour with a high confidence. Maximum amplitudes of sinusoidal variations are DeltaR < 0.009 mag and Delta V-R < 0.7% for a mean value of the R-band circular polarization of V-R = -9.1 +/- 0.3%. Combined with earlier results by other authors, our observation suggests that LP 790-29 is, in fact, an extremely slowly rotating single white dwarf and not an unrecognized fast rotator and/or disguised cataclysmic variable."],["dc.identifier.doi","10.1051/0004-6361:20011478"],["dc.identifier.fs","19137"],["dc.identifier.isi","000173343100014"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9720"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/44434"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Edp Sciences S A"],["dc.relation.issn","1432-0746"],["dc.relation.orgunit","Fakultät für Physik"],["dc.title","The high-field magnetic white dwarf LP790-29: Not a fast rotator"],["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","L37"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","L40"],["dc.bibliographiccitation.volume","354"],["dc.contributor.author","Reinsch, K."],["dc.contributor.author","van Teeseling, A."],["dc.contributor.author","King, A. R."],["dc.contributor.author","Beuermann, Klaus"],["dc.date.accessioned","2018-11-07T10:15:17Z"],["dc.date.available","2018-11-07T10:15:17Z"],["dc.date.issued","2000"],["dc.description.abstract","We present new results of our X-ray monitoring of the transient binary supersoft X-ray source RX J0513.9-6951 in the LMC and of our re-analysis of optical light curves obtained during the MACHO project. We have covered a complete X-ray outburst cycle with the ROSAT HRI detector. From the amplitude and timescale of the soft X-ray variability, tight limits are derived for the temporal behaviour of the white-dwarf radius and the effective temperature of its envelope. A limit-cycle model is proposed to explain the observed optical and X-ray variability, the characteristic timescales of the durations of the X-ray on and off states, and those of the transitions between both states. Our observations confirm that the radius changes of the white-dwarf envelope occur on the Kelvin-Helmholtz timescale. The duration of the X-ray on and off states is compatible with the viscous timescales of the inner and outer accretion disk, respectively."],["dc.identifier.isi","000085955700010"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/40780"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Edp Sciences S A"],["dc.relation.issn","0004-6361"],["dc.title","A limit-cycle model for the binary supersoft X-ray source RX J0513.9-6951"],["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","A91"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","634"],["dc.contributor.author","Beuermann, K."],["dc.contributor.author","Burwitz, V."],["dc.contributor.author","Reinsch, K."],["dc.contributor.author","Schwope, A."],["dc.contributor.author","Thomas, H.-C."],["dc.date.accessioned","2020-12-10T18:11:53Z"],["dc.date.available","2020-12-10T18:11:53Z"],["dc.date.issued","2020"],["dc.identifier.doi","10.1051/0004-6361/201936626"],["dc.identifier.eissn","1432-0746"],["dc.identifier.issn","0004-6361"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/74173"],["dc.notes.intern","DOI Import GROB-354"],["dc.title","Neglected X-ray discovered polars"],["dc.title.alternative","II. The peculiar eclipsing binary HY Eridani"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","647"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","655"],["dc.bibliographiccitation.volume","463"],["dc.contributor.author","Beuermann, Klaus"],["dc.contributor.author","Euchner, F."],["dc.contributor.author","Reinsch, K."],["dc.contributor.author","Jordan, S."],["dc.contributor.author","Gaensicke, B. T."],["dc.date.accessioned","2018-11-07T11:05:08Z"],["dc.date.available","2018-11-07T11:05:08Z"],["dc.date.issued","2007"],["dc.description.abstract","Context. The magnetic fields of the accreting white dwarfs in magnetic cataclysmic variables (mCVs) determine the accretion geometries, the emission properties, and the secular evolution of these objects. Aims. We determine the structure of the surface magnetic fields of the white dwarf primaries in magnetic CVs using Zeeman tomography. Methods. Our study is based on orbital-phase resolved optical flux and circular polarization spectra of the polars EF Eri, BL Hyi, and CP Tuc obtained with FORS1 at the ESO VLT. An evolutionary algorithm is used to synthesize best fits to these spectra from an extensive database of pre-computed Zeeman spectra. The general approach has been described in previous papers of this series. Results. The results achieved with simple geometries as centered or offset dipoles are not satisfactory. Significantly improved fits are obtained for multipole expansions that are truncated at degree l(max) = 3 or 5 and include all tesseral and sectoral components with 0 <= m <= l. The most frequent field strengths of 13, 18, and 10 MG for EF Eri, BL Hyi, and CP Tuc, and the ranges of field strength covered are similar for the dipole and multipole models, but only the latter provide access to accreting matter at the right locations on the white dwarf. The results suggest that the field geometries of the white dwarfs in short-period mCVs are quite complex, with strong contributions from multipoles higher than the dipole in spite of a typical age of the white dwarfs in CVs in excess of 1 Gyr. Conclusions. It is feasible to derive the surface field structure of an accreting white dwarf from phase-resolved low-state circular spectropolarimetry of sufficiently high signal-to-noise ratio. The fact that independent information is available on the strength and direction of the field in the accretion spot from high-state observations helps in unraveling the global field structure."],["dc.identifier.doi","10.1051/0004-6361:20066332"],["dc.identifier.fs","54577"],["dc.identifier.isi","244069700028"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9381"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/51999"],["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","Zeeman tomography of magnetic white dwarfs"],["dc.title.original","9381"],["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","984"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","998"],["dc.bibliographiccitation.volume","382"],["dc.contributor.author","Eisenbart, S."],["dc.contributor.author","Beuermann, Klaus"],["dc.contributor.author","Reinsch, K."],["dc.contributor.author","Gansicke, B. T."],["dc.date.accessioned","2018-11-07T10:32:03Z"],["dc.date.available","2018-11-07T10:32:03Z"],["dc.date.issued","2002"],["dc.description.abstract","We present phase-resolved infrared and optical spectrophotometry of the intermediate polar EXHya supplemented by archival ultraviolet data. The spin-modulated emission from the accretion funnel and the emission from the accretion disk or ring contain substantial optically thin components. The white dwarf dominates the unmodulated flux in the ultraviolet and is identified by numerous absorption lines. Metal absorption in the accretion curtain may add to the observed spectral features. The secondary star is of spectral type M4 +/- 1 and is detected by its ellipsoidal modulation. We derive a distance of 65 +/- 11 pc which makes EX Hydrae one of the closest cataclysmic variables with a known distance. The luminosity derived from the integrated overall spectral energy distribution is 3 x 10(32) erg s(-1). The accretion rate of 3 x 10(15) g s(-1) (for an 0.6 M-. white dwarf) is in reasonable agreement with the rates expected from angular momentum loss by gravitational radiation and from the observed spin-up of the white dwarf."],["dc.identifier.doi","10.1051/0004-6361:20011655"],["dc.identifier.fs","19124"],["dc.identifier.isi","000174182900024"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9722"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/44255"],["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","Multi-wavelength spectrophotometry of EX Hydrae"],["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.artnumber","A76"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","516"],["dc.contributor.author","Traulsen, Imke"],["dc.contributor.author","Reinsch, K."],["dc.contributor.author","Schwarz, R."],["dc.contributor.author","Dreizler, Stefan"],["dc.contributor.author","Beuermann, Klaus"],["dc.contributor.author","Schwope, Axel D."],["dc.contributor.author","Burwitz, Vadim"],["dc.date.accessioned","2018-11-07T08:42:26Z"],["dc.date.available","2018-11-07T08:42:26Z"],["dc.date.issued","2010"],["dc.description.abstract","Context. The energy balance of cataclysmic variables with strong magnetic fields is a central subject in understanding accretion processes on magnetic white dwarfs. With XMM-Newton, we perform a spectroscopic and photometric study of soft X-ray selected polars during their high states of accretion. Aims. On the basis of X-ray and optical observations of the magnetic cataclysmic variable AI Tri, we derive the properties of the spectral components, their flux contributions, and the physical structure of the accretion region in soft polars. Methods. We use multi-temperature approaches in our xspec modeling of the X-ray spectra to describe the physical conditions and the structures of the post-shock accretion flow and the accretion spot on the white-dwarf surface. In addition, we investigate the accretion geometry of the system by completing a timing analysis of the photometric data. Results. Flaring soft X-ray emission from the heated surface of the white dwarf dominates the X-ray flux during roughly 70% of the binary cycle. This component deviates from a single black body and can be described by a superimposition of mildly absorbed black bodies with a Gaussian temperature distribution between kT(bb,low) := 2 eV and kT(bb,high) = 43.9(-32)(+3.3) eV, and N(H,ISM) = 1.5(-0.7)(+0.8) x 10(20) cm(-2). In addition, weaker hard X-ray emission is visible nearly all the time. The spectrum from the cooling post-shock accretion flow is most closely fitted by a combination of thermal plasma MEKAL models with temperature profiles adapted from prior stationary two-fluid hydrodynamic calculations. The resulting plasma temperatures lie between kT(MEKAL,low) = 0.8(-0.2)(+0.4) keV and kT(MEKAL,high) = 20.0(-6.1)(+9.9) keV; additional intrinsic, partial-covering absorption is on the order of N(H,int) = 3.3(1.2)(+2.5) x 10(23) cm(-2). The soft X-ray light curves show a dip during the bright phase, which can be interpreted as self-absorption in the accretion stream. Phase-resolved spectral modeling supports the picture of one-pole accretion and self-eclipse. One of the optical light curves corresponds to an irregular mode of accretion. During a short XMM-Newton observation at the same epoch, the X-ray emission of the system is clearly dominated by the soft component."],["dc.description.sponsorship","DLR"],["dc.identifier.doi","10.1051/0004-6361/200913201"],["dc.identifier.fs","581081"],["dc.identifier.isi","280275400091"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9406"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/19701"],["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","X-ray spectroscopy and photometry of the long-period polar AI Trianguli with XMM-Newton"],["dc.title.original","9406"],["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"]]