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Veenhuizen, Hans
Publications (10 of 15) Show all publications
Eriksson, M., Nilsson, H., Veenhuizen, H. & Long, K. S. (2008). Modeling of C IV pumped fluorescence of Fe II in symbiotic stars. Astronomy and Astrophysics, 477(1), 255-265
Open this publication in new window or tab >>Modeling of C IV pumped fluorescence of Fe II in symbiotic stars
2008 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 477, no 1, p. 255-265Article in journal (Refereed) Published
Abstract [en]

Aims. We describe how the C IV lambda 1548.18 line pumps the 1548.20 and 1548.41 angstrom channels of Fe II in symbiotic stars through the process known as photo-ionization by accidental resonance (PAR). We describe where and why Fe II fluorescence arises in symbiotic stars and whether the Fe II lambda 1548.41 channel can only be activated when there is a white-dwarf wind present in the system. Further, we aim to show how an analysis of the PAR-pumped lines helps to understand the phyisical conditions that they manifest. Methods. We calculate intensities of the C IV-pumped Fe II fluorescence lines in symbiotic stars, corresponding to the y(4)H(11/)2 and w(2)D(3/2) levels, based on a simple geometrical model of the emitting regions. We apply the model to seven symbiotic stars, known to have Fe II fluorescence lines pumped by C IV in their spectra. We compare the predicted intensities to the observed intensities of the selected symbiotic stars. Results. We find that we can reproduce the observed fluorescence intensities of the seven symbiotic stars in our sample, using parameters that are consistent with their known properties. We show that PAR-produced lines can be used as a diagnostic tool to derive important physical parameters of a stellar system. We suggest that the detection of Fe II lines corresponding to the w2D3/2 level in certain symbiotic stars provide evidence of hot shells expanding with velocities of at least hundreds km s(-1) in those systems.

National Category
Physical Sciences
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-1604 (URN)10.1051/0004-6361:20078420 (DOI)
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2017-12-12Bibliographically approved
Eriksson, M., Veenhuizen, H. & Nilsson, H. (2007). Fluorescence Fe II lines as traces of fast outflows of white dwarf winds. Baltic Astronomy, 16(01), 95-97
Open this publication in new window or tab >>Fluorescence Fe II lines as traces of fast outflows of white dwarf winds
2007 (English)In: Baltic Astronomy, ISSN 1392-0049, Vol. 16, no 01, p. 95-97Article in journal (Refereed) Published
Abstract [en]

A set of equations are put into a code forming a procedure to derive intensities of fluorescence lilies based on both physical properties of the fluorescent plasma and its location relative to the origin of the pumping emission. In a first test, the code is applied to symbiotic stars, and effort is made to explain the circumstances under which the two known Fell channels pumped by C IV are activated. For the channel at 1548.204 angstrom, which is most frequently observed to be active, there is a good agreement between the results of the calculations and the observed Fell line strengths. Fluorescence lines resulting from pumping through the other channel at 1548.411 angstrom can occur, according to the results of the calculations, only in the systems where a fast outflow from the white dwarf wind is present. The evidences of the white dwarf winds are found in the literature for all the symbiotic systems in which observation of the Fell fluorescence lines from the w(2)D(3/2) level is reported. 

National Category
Physical Sciences
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-1495 (URN)
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2017-12-12Bibliographically approved
Eriksson, M., Johansson, S., Wahlgren, G. M., Veenhuizen, H., Munari, U. & Siviero, A. (2005). Bowen excitation of NIII lines in symbiotic stars. Astronomy & Astrophysics, 434(05/2005), 397-404
Open this publication in new window or tab >>Bowen excitation of NIII lines in symbiotic stars
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2005 (English)In: Astronomy & Astrophysics, Vol. 434, no 05/2005, p. 397-404Article in journal (Refereed) Published
National Category
Natural Sciences
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-1605 (URN)
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2011-09-30Bibliographically approved
Eriksson, M., Veenhuizen, H., Wahlgren, G. M. & Johansson, S. (2004). Fe II fluorescence in symbiotic stars. In: Allen C. and Scarfe C. (Ed.), Revista Mexicana de Astronomia y Astrofisica Conference Series 21. Paper presented at The Environment and Evolution of Double and Multiple Stars (pp. 132-136). Merida, Yucatan, Mexico
Open this publication in new window or tab >>Fe II fluorescence in symbiotic stars
2004 (English)In: Revista Mexicana de Astronomia y Astrofisica Conference Series 21 / [ed] Allen C. and Scarfe C., Merida, Yucatan, Mexico, 2004, p. 132-136Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Merida, Yucatan, Mexico: , 2004
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-4696 (URN)
Conference
The Environment and Evolution of Double and Multiple Stars
Note
Nummer: Available from: 2010-04-27 Created: 2010-04-27 Last updated: 2011-09-29Bibliographically approved
Baltzer, P., Chau, F. T., Eland, J. H., Karlsson, L., Lundqvist, M., Rostas, J., . . . Wannberg, B. (1996). A study of the vibronic structure in the HeI excited photoelectron spectrum of CO2 involving the X 2Pig and A 2Piu ionic states. The Journal of Chemical Physics, 104(22/June 8), 8922-8931
Open this publication in new window or tab >>A study of the vibronic structure in the HeI excited photoelectron spectrum of CO2 involving the X 2Pig and A 2Piu ionic states
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1996 (English)In: The Journal of Chemical Physics, ISSN 00219606, Vol. 104, no 22/June 8, p. 8922-8931Article in journal (Refereed) Published
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-1496 (URN)
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2011-09-16Bibliographically approved
Veenhuizen, H., Wannberg, B., Mattsson, L., Norell, K. E., Karlsson, L. & Siegbahn, K. (1986). Acquisition and processing of angle-resolved photoelectron spectra excited with focussed polarized resonance radiation. Journal of Electron Spectroscopy and Related Phenomena, 41(2), 187-203
Open this publication in new window or tab >>Acquisition and processing of angle-resolved photoelectron spectra excited with focussed polarized resonance radiation
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1986 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 41, no 2, p. 187-203Article in journal (Refereed) Published
Abstract [en]

A system for the acquisition of angle-resolved photoelectron spectra is described. The sample gas is excited by VUV resonance radiation, which is polarized to about 95% using a fully rotatable fourfold reflection polarizer. One of the mirrors is toroidally shaped in order to focus the radiation into the sample gas cell. This design gives count rates comparable to those obtained by an unpolarized source, and at a greatly reduced background level. A computer controlled system has been developed to automate the recording procedure. It allows for simultaneous recordings of the spectra at the different angular settings, thus eliminating the effects of intensity drifts. Details of calibration procedures and data processing, including spectrum analysis, are given along with a discussion of the accuracy of the results. To illustrate the performance, measured β-values for the main components of the four outermost photoelectron bands in the Hel excited spectrum of CO2 are presented. 

National Category
Physical Sciences
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-1497 (URN)10.1016/0368-2048(86)85003-4 (DOI)
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2017-12-12Bibliographically approved
Wannberg, B., Veenhuizen, H., Norell, K. E., Karlsson, L., Mattsson, L. & Siegbahn, K. (1986). Angular distribution of photoelectrons from p levels in Ar, Kr and Xe close to threshold. Journal of Physics B: Atomic, Molecular and Optical Physics, 19(15), 2267-2277
Open this publication in new window or tab >>Angular distribution of photoelectrons from p levels in Ar, Kr and Xe close to threshold
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1986 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 19, no 15, p. 2267-2277Article in journal (Refereed) Published
Abstract [en]

Using a DC discharge VUV source equipped with a rotating, focusing reflection polariser in conjunction with a hemispherical electron spectrometer, the angular distribution of photoelectrons from the outermost p levels in the noble gases Ar, Kr and Xe was measured in the kinetic-energy region 0-3 eV. Discharges in Ne, Ar, Kr, Xe and N2 are used to obtain photons with energies in the range 11-19 eV. For photon energies between the ionisation thresholds for the P3/2 and P1/2 levels, observed rapid oscillations in beta are correlated with resonances with autoionising states. For higher photon energies, the energy dependence of beta is smooth. 

National Category
Physical Sciences
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-1499 (URN)10.1088/0022-3700/19/15/008 (DOI)
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2017-12-12Bibliographically approved
Veenhuizen, H., Wannberg, B., Mattsson, L., Norell, K. E., Nohre, C., Karlsson, L. & Siegbahn, K. (1986). High resolution angle-resolved photoelectron spectrum of CO2, excited with polarized resonance radiation. Journal of Electron Spectroscopy and Related Phenomena, 41(2), 205-223
Open this publication in new window or tab >>High resolution angle-resolved photoelectron spectrum of CO2, excited with polarized resonance radiation
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1986 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 41, no 2, p. 205-223Article in journal (Refereed) Published
Abstract [en]

The He(I) excited and angle-resolved photoelectron spectrum of CO2 is investigated using a focussing VUV-polarizer. High resolution combined with the additional information given by comparing spectra taken at different angles permits detailed analysis of the vibrational structure. β-values are given for all vibrational components hitherto observed in the photoelectron spectrum of the ≈X, ≈A,≈B and ≈C electronic bands. Single excitations of the v3 mode with vibrational energies 181 meV in the estate and 279 meV in the ≈B-state are reported. The peak at 360 meV vibrational energy in the (≈C-state is reinterpreted as a single v3 excitation. The β-values of the most intense peaks are also measured using Ne(I) (16.67 and 16.85 eV), Ne(II) (26.86 and 26.95 eV) and He(II) (40.81) resonance radiations. 

National Category
Physical Sciences
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-1498 (URN)10.1016/0368-2048(86)85004-6 (DOI)
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2017-12-12Bibliographically approved
Veenhuizen, H. (1984). High resolution and angle-resolved UV photoelectron spectroscopy applied to free molecules. (Doctoral dissertation). Uppsala: Uppsala University
Open this publication in new window or tab >>High resolution and angle-resolved UV photoelectron spectroscopy applied to free molecules
1984 (English)Doctoral thesis, monograph (Other academic)
Place, publisher, year, edition, pages
Uppsala: Uppsala University, 1984. p. 24, in addition 12 articles
Series
Acta Universitatis Upsaliensis, ISSN 0345-0058
Keywords
Natural sciences
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-7540 (URN)91-554-1579-2 (ISBN)
Public defence
(English)
Supervisors
Available from: 2010-08-23 Created: 2010-08-19 Last updated: 2010-08-23Bibliographically approved
Veenhuizen, H. (1984). High resolution and angle-resolved UV photoelectron spectroscopy applied to free molecules. (Doctoral dissertation). Uppsala
Open this publication in new window or tab >>High resolution and angle-resolved UV photoelectron spectroscopy applied to free molecules
1984 (English)Doctoral thesis, monograph (Other academic)
Place, publisher, year, edition, pages
Uppsala: , 1984. p. 24, in addition 12 articles
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-3047 (URN)91-554-1579-2 (ISBN)
Public defence
(English)
Supervisors
Available from: 2007-12-21 Created: 2010-04-23 Last updated: 2010-04-23

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