Oddbjørn Engvold

• Engvold, Oddbjørn & Vial, Jean-Claude (2024). THE ROLE OF PROMINENCES IN THE HISTORY OF SOLAR PHYSICS. Journal of Astronomical History and Heritage. ISSN 1440-2807. 27(1), p. 3–27. doi: 10.3724/SP.J.1440-2807.2024.01.01. Full text in Research Archive Show summary

  The very outer solar atmosphere (corona) is very hot with temperatures over a million degrees K, while the photosphere is of the order of 5000 K. Embedded in this hot outer corona are cool, QUOTE ≤ 10,000 K, magnetic structures called solar prominences. As seen on the disk, they are long filamentary structures while on the solar limb they look like intricate loops. In this paper, we present the development of our understanding of solar prominences, which have played a central role in the development of solar science. Solar prominences were first observed during the few minute episodes of total eclipses. The introduction of spectroscopy allowed continuous observations, which also led to information on temperatures, temporal variations and dynamics of the associated plasma. The discovery of strong magnetic fields in sunspots provided a breakthrough in our understanding of the physics of the Sun. Weaker magnetic fields formed both the large and small-scale structures of prominences, their time-variable shapes, and explained why they could remain floating high above the solar surface in the less dense corona. Appearing as dark, thin, elongated filaments against a brighter solar disk, they provided further information through their interaction with and dependence on how magnetic fields are distributed on the solar surface, in the chromosphere and corona. Access to X-ray and short-wavelength ultraviolet radiation in prominences from spacecraft revealed large ranges of temperature in thin layers between the 10,000-degree prominence cores and the surrounding million-degree corona. The advent of increasingly more powerful computers has led to advanced modelling of prominence plasma based on radiative transfer and magnetohydrodynamic (MHD) calculations. Theoretical and observational progress has opened up new possible formation mechanisms. The spectacular eruptions of solar prominences have led to a considerable amount of observational and theoretical work on possibly similar events on other stars, which could affect the existence of life on their orbiting planets.

• Engvold, Oddbjørn (2019). IAU’s Interaction with Young Astronomers. Proceedings of the International Astronomical Union. ISSN 1743-9213. 13, p. 75–78. doi: 10.1017/S1743921319000152. Full text in Research Archive Show summary

  The IAU promotes astronomy as a tool to strengthen science education of young people in developing regions through its International Schools for Young Astronomers (ISYA) and a Teaching for Astronomy Development (TAD) programme. This article describes briefly the strategy, organization and development of these programmes. The contents of the courses, tutorials and aims for longer-term effects of these programmes are described with focus on the ISYAs.

• Engvold, Oddbjørn & Zirker, Jack B. (2018). High-Resolution Ground-Based Observations of the Sun. In Engvold, Oddbjørn; Vial, Jean-Claude & Skumanich, Andrew (Ed.), The Sun as a Guide to Stellar Physics. Elsevier. ISSN 9780128143353. p. 419–441. doi: 10.1016/B978-0-12-814334-6.00015-7. Full text in Research Archive
• Zirker, Jack B. & Engvold, Oddbjørn (2018). The Sun's Role in Astrophysics. In Engvold, Oddbjørn; Vial, Jean-Claude & Skumanich, Andrew (Ed.), The Sun as a Guide to Stellar Physics. Elsevier. ISSN 9780128143353. p. 1–26. doi: 10.1016/B978-0-12-814334-6.00001-7. Full text in Research Archive
• Zirker, Jack B. & Engvold, Oddbjørn (2017). Why is the Sun's corona so hot? Why are prominences so cool? Physics Today. ISSN 0031-9228. 70(8), p. 36–43. doi: 10.1063/PT.3.3659. Full text in Research Archive Show summary

  © 2017 American Institute of Physics.

• Martin, Sara F.; Engvold, Oddbjørn; Lin, Yong & Silva, Jacqueline Alves da (2016). Distinguishing between coronal cloud prominences and channel prominences and their associations with solar and stellar flares. Proceedings of the International Astronomical Union. ISSN 1743-9213. 11(S320), p. 278–287. doi: 10.1017/S1743921316002209. Full text in Research Archive
• Engvold, Oddbjørn & Zirker, Jack B. (2016). The Parallel Worlds of Christoph Scheiner and Galileo Galilei. Journal for the History of Astronomy. ISSN 0021-8286. 47(3), p. 332–345. doi: 10.1177/0021828616662406. Full text in Research Archive
• Engvold, Oddbjørn (2015). Description and Classification of Prominences. In Vial, J.-C. & Engvold, Oddbjørn (Ed.), Solar Prominences. Springer. ISSN 9783319104157. p. 31–60. doi: 10.1007/978-3-319-10416-4_2. Full text in Research Archive
• Scullion, Eamon; Engvold, Oddbjørn; Lin, Yong & Rouppe, Van Der Voort Luc (2015). Observing Cascades of Solar Bullets at High Resolutions. II. The Astrophysical Journal (ApJ). ISSN 0004-637X. 814(2). doi: 10.1088/0004-637X/814/2/123. Full text in Research Archive Show summary

  High resolution observations from the Swedish 1-m Solar Telescope revealed bright, discrete, blob-like structures (which we refer to as solar bullets) in the Hα 656.28 nm line core that appear to propagate laterally across the solar atmosphere as clusters in active regions (ARs). These small-scale structures appear to be field aligned and many bullets become triggered simultaneously and traverse collectively as a cluster. Here, we conduct a follow-up study on these rapidly evolving structures with coincident observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly. With the co-aligned data sets, we reveal (a) an evolving multithermal structure in the bullet cluster ranging from chromospheric to at least transition region temperatures, (b) evidence for cascade-like behavior and corresponding bidirectional motions in bullets within the cluster, which indicate that there is a common source of the initial instability leading to bullet formation, and (c) a direct relationship between co-incident bullet velocities observed in Hα and He ii 30.4 nm and an inverse relationship with respect to bullet intensity in these channels. We find evidence supporting that bullets are typically composed of a cooler, higher density core detectable in Hα with a less dense, hotter, and fainter co-moving outer sheath. Bullets unequivocally demonstrate the finely structured nature of the AR corona. We have no clear evidence for bullets being associated with locally heated (or cooled), fast flowing plasma. Fast MHD pulses (such as solitons) could best describe the dynamic properties of bullets whereas the presence of a multithermal structure is new. Reproduced with permission from the Astrophysical Journal. © IOP Publishing

• Martin, Sara F.; Panasenco, O.; Berger, M. A.; Engvold, Oddbjørn; Lin, Yong & Pevtsov, A. A. [Show all 7 contributors for this article] (2012). The Build-Up to Eruptive Solar Events Viewed as the Development of Chiral Systems. Astronomical Society of the Pacific Conference Series. ISSN 1050-3390. 463, p. 157–173. Full text in Research Archive
• Ballester, JL; Arregui, I.; Oliver, R.; Terradas, J.; Soler, Roberto & Lin, Yong [Show all 9 contributors for this article] (2012). Prominence seismology using ground- and space-based observations. EAS Publications Series. ISSN 1633-4760. 55, p. 169–174. doi: 10.1051/eas/1255023. Full text in Research Archive
• Lin, Yong; Engvold, Oddbjørn & Rouppe, Van Der Voort Luc (2012). SMALL-SCALE, DYNAMIC BRIGHT BLOBS IN SOLAR FILAMENTS AND ACTIVE REGIONS. The Astrophysical Journal (ApJ). ISSN 0004-637X. 747(2). doi: 10.1088/0004-637X/747/2/129. Full text in Research Archive
• Lin, Yong; Soler, Roberto; Engvold, Oddbjørn; Ballester, JL; Langangen, Øystein & Oliver, R. [Show all 7 contributors for this article] (2009). SWAYING THREADS OF A SOLAR FILAMENT. The Astrophysical Journal (ApJ). ISSN 0004-637X. 704(1), p. 870–876. doi: 10.1088/0004-637X/704/1/870. Full text in Research Archive
• Lin, Yong; Martin, Sara F. & Engvold, Oddbjørn (2008). Filament Substructures and their Interrelation. Astronomical Society of the Pacific Conference Series. ISSN 1050-3390. 383, p. 235–242. Full text in Research Archive
• Engvold, Oddbjørn (2008). Observational aspects of prominence oscillations. In Erdélyi, R. & Mendoza-Briceno, C. A. (Ed.), Waves and Oscillations in the Solar Atmosphere: Heating and Magneto-Seismology. Cambridge University Press. ISSN 9780521874694. p. 152–157. Full text in Research Archive
• Martin, Sara F.; Panasenco, Olya; Engvold, Oddbjørn & Lin, Yong (2008). The link between CMEs, filaments and filament channels. Annales Geophysicae. ISSN 0992-7689. 26, p. 1–6. Full text in Research Archive
• Martin, Sara F.; Lin, Yong & Engvold, Oddbjørn (2008). A Method of Resolving the 180 degree Ambiguity Employing the Chirality of Solar Features. Solar Physics. ISSN 0038-0938. 250, p. 31–52. doi: 10.1007/s11207-008-9194-8. Full text in Research Archive
• Lin, Yong; Martin, SF; Engvold, Oddbjørn; Rouppe, Van Der Voort Luc & Noort, M van (2008). On small active region filaments, fibrils and surges. Advances in Space Research. ISSN 0273-1177. 42, p. 803–811. doi: 10.1016/j.asr.2007.05.052. Full text in Research Archive
• Lin, Yong; Engvold, Oddbjørn; Rouppe, Van Der Voort Luc & Noort, Michiel Jan van (2007). Evidence of Traveling Waves in Filament Threads. Solar Physics. ISSN 0038-0938. 246(1), p. 65–72. doi: 10.1007/s11207-007-0402-8. Full text in Research Archive
• Lin, Yong; Engvold, Oddbjørn; Voort, Luc Rouppe van der; Toutain, Jun Elin Wiik & Berger, T.E. (2005). Thin Threads of Solar Filaments. Solar Physics. ISSN 0038-0938. 226, p. 239–254. doi: 10.1007/s11207-005-6876-3. Full text in Research Archive
• Lin, Yong; Toutain, Jun Elin Wiik; Engvold, Oddbjørn; Voort, Luc Rouppe van der & Frank, Zoe A. (2005). Solar Filaments and Photospheric Network. Solar Physics. ISSN 0038-0938. 227, p. 283–297. doi: 10.1007/s11207-005-1111-9. Full text in Research Archive
• Ulvås, Vidar Aarum & Engvold, Oddbjørn (2003). Why does the spotted UX Ari system get bluer as it gets darker? Astronomy and Astrophysics (A & A). ISSN 0004-6361. 399, p. L11–L14. Full text in Research Archive Show summary

  We present simplified calculations of UX Ari B-V colour index and V magnitude for a range of parameter values. The results of our calculations are compared to previously published measurements. We find that our calculations reproduce the well established colour-brightness relation (UX Ari gets bluer as it gets darker) only if the dark spots on the surface of the K star are accompanied by bright facular areas. There is currently an ambiguity between the temperature of the facular areas and the portion of the stellar surface occupied by them.

• Lin, Yong; Engvold, Oddbjørn & Wiik, J. E. (2003). Counterstreaming in a large polar crown filament. Solar Physics. ISSN 0038-0938. 216, p. 109–120. Full text in Research Archive
• Engvold, Oddbjørn & Maltby, Per (2003). Professor Eberhart Jensen (1922-2003). Aftenposten (morgenutg. : trykt utg.). ISSN 0804-3116. Full text in Research Archive
• Engvold, Oddbjørn (2003). Eberhart Jensen (1922-2003). Astronomi. ISSN 0802-7587. 33(2), p. 46–46. Full text in Research Archive
• Engvold, Oddbjørn & Maltby, Per (2003). Eberhart Jensen (1922-2003). Fra Fysikkens Verden. ISSN 0015-9247. 65(1), p. 3–4. Full text in Research Archive
• Engvold, Oddbjørn & Ulvås, Vidar Aarum (2003). Separation of high resolution spectra of the multiple star system UX Ari. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 402, p. 1043–1053. Full text in Research Archive
• Deng, Y.Y.; Lin, Yong; Schmieder, Birgitte & Engvold, Oddbjørn (2002). Filament activation and magnetic reconnection. Solar Physics. ISSN 0038-0938. 209, p. 153–170. Full text in Research Archive
• Engvold, Oddbjørn; Jakobsson, Hans; Tandberg-Hanssen, E.; Gurman, Joe B. & Moses, Daniel (2001). On the nature of prominence absorption and emission in highly ionized iron and in neutral hydrogen. Solar Physics. ISSN 0038-0938. 202, p. 293–308. Full text in Research Archive
• Pecseli, Hans & Engvold, Oddbjørn (2000). Modeling of prominence threads in magnetic fields: Levitation by imcompressible MHD waves. Solar Physics. ISSN 0038-0938. 194, p. 73–86. Full text in Research Archive
• Deng, Y.Y.; Schmieder, Birgitte; Engvold, Oddbjørn; Luca, E E De & Golub, L. (2000). Emergence of sheared magnetic flux tubes in an active region observed with the SVST and TRACE. Solar Physics. ISSN 0038-0938. 195(2 (+ CD-ROM)), p. 347–366. Full text in Research Archive
• Elgarøy, Øystein; Engvold, Oddbjørn & Lund, N. (1999). The Wilson-Bappu effect of the MgIIk line - dependence on stellar temperature, activity and metallicity. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 343, p. 222–228. Full text in Research Archive
• Elgarøy, Øystein; Jorås, P; Engvold, Oddbjørn; Jensen, E; Pettersen, Bjørn Ragnvald & Ayres, T. R. [Show all 11 contributors for this article] (1988). Ultraviolet emission lines and optical photometry of the flare star AT Microskopii. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 193, p. 211–221. Full text in Research Archive
• Singh, K.P.; Slijkhuis, S.; Westergaard, N.J.; Schnopper, H.W.; Elgarøy, Øystein & Engvold, Oddbjørn [Show all 7 contributors for this article] (1987). X-ray spectrum of sigma Geminorum: An RS Canum Venaticorum type binary. Monthly notices of the Royal Astronomical Society. ISSN 0035-8711. 224(2), p. 481–487. doi: 10.1093/mnras/224.2.481. Full text in Research Archive

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• Engvold, Oddbjørn; Vial, Jean-Claude & Skumanich, Andrew (2018). The Sun as a Guide to Stellar Physics. Elsevier. ISBN 9780128143353. 522 p. Full text in Research Archive
• Vial, J.-C. & Engvold, Oddbjørn (2015). Solar Prominences. Springer. ISBN 9783319104157. 488 p. Full text in Research Archive
• Engvold, Oddbjørn (2006). Highlights of astronomy. Astronomical Society of the Pacific. ISBN 9781583811894. 1085 p. Full text in Research Archive
• Engvold, Oddbjørn & Harvey, J.W. (2001). Physics of the solar corona and transition region. Part II, Proceedings of the Monterey Workshop, held in Monterey, California, August 1999. Kluwer Academic Publishers. ISBN 9780792370437. 392 p. Full text in Research Archive
• Engvold, Oddbjørn & Harvey, J.W. (2000). Physics of the Solar Corona and Transition Region : TRACE Workshop, Monterey, CA, 24-27 August 1999. Part 1. Kluwer Academic Publishers, Dordrecht. ISBN 9780792363576. 497 p. Full text in Research Archive

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• Engvold, Oddbjørn (2024). Norges første forskningsinstitusjon. Apollon : Forskningsmagasin for Universitetet i Oslo. ISSN 0803-6926. 2024(2), p. 58–58. Full text in Research Archive
• Brekke, Pål & Engvold, Oddbjørn (2022). To legender ruver innen moderne naturvitenskap. Begge ble møtt med motstand. [Journal]. Aftenposten. Full text in Research Archive
• Thue, Sivert & Engvold, Oddbjørn (2022). Solen: Kunst og astrofysikk møtes. Full text in Research Archive
• Rutten, Robert; Engvold, Oddbjørn & Nieuwenhuizen, Adrianus C. T. (2022). Cornelis de Jager: In Memoriam. Solar Physics. ISSN 0038-0938. 297(1). doi: 10.1007/s11207-021-01946-7. Full text in Research Archive
• Lin, Yong & Engvold, Oddbjørn (2009). Evidences for kink MHD waves in filament threads. Full text in Research Archive
• Lin, Yong & Engvold, Oddbjørn (2009). What can be learned from studies of the small-scale structures of solar filaments? Full text in Research Archive
• Engvold, Oddbjørn; Lilje, Per Barth & Stabell, Rolf (2009). In Memoriam: Rolf Brahde (1918-2009). Fra Fysikkens Verden. ISSN 0015-9247. p. 72–72. Full text in Research Archive
• Lin, Yong; Soler, Roberto & Engvold, Oddbjørn (2008). Swaying threads of solar filaments. Full text in Research Archive
• Lin, Yong; Engvold, Oddbjørn; Martin, Sara F. & Panasenco, Olga (2008). The Unique 3D Magnetic Structure of Filaments. Full text in Research Archive
• Martin, Sara F.; Engvold, Oddbjørn; Panasenco, Olga & Lin, Yong (2007). The CME Link to Filaments and Filament Channels. Full text in Research Archive
• Lin, Yong; Martin, Sara F. & Engvold, Oddbjørn (2007). Filament substructures and their interrelation. Full text in Research Archive
• Martin, Sara F.; Engvold, Oddbjørn & Lin, Yong (2007). Comparisons of the Spines of Prominences (Filaments) in H-alpha and He II(304A) Images. Full text in Research Archive
• Lin, Yong; Martin, Sara F. & Engvold, Oddbjørn (2006). "Coronal Cloud" Prominences And Their Association With Coronal Mass Ejections. Full text in Research Archive
• Martin, Sara F.; Lin, Yong & Engvold, Oddbjørn (2006). A Simple Method of Resolving the 180 Degree Ambiguity Employing the Chirality of Solar Features. Full text in Research Archive
• Engvold, Oddbjørn (2006). The IAU Role. Full text in Research Archive
• Lin, Yong; Martin, Sara F.; Engvold, Oddbjørn; Rouppe, Van Der Voort Luc & Noort, Michiel Jan van (2006). Dynamics of an active region filament, fibrils and surges in high resolution. Full text in Research Archive
• Lin, Yong; Engvold, Oddbjørn; Rouppe, Van Der Voort Luc & Noort, Michiel Jan van (2006). Evidence for propagating waves in a quiescent fialment. Full text in Research Archive
• Engvold, Oddbjørn & Kalland, Arne (2005). Klimaforskning og ytringsfriheten. Forskerforum. ISSN 0800-1715. Full text in Research Archive
• Engvold, Oddbjørn & Kalland, Arne (2004). Politisk styring av forskning. Forskerforum. ISSN 0800-1715. p. 30–31. Full text in Research Archive
• Engvold, Oddbjørn & Lilje, Per Vidar Barth (2003). Eberhart Jensen 1922 - 2003. Astronomy & Geophysics. ISSN 1366-8781. 44(2.38). Full text in Research Archive
• Schmieder, Birgitte; Engvold, Oddbjørn; Lin, Yong; Deng, Y.Y. & Mein, N. (2002). Magnetic cancellation and small-scale activity in an AR filament. Full text in Research Archive
• Engvold, Oddbjørn (2002). Tema Klimaforskning: Frykter ensretting av klimadebatten. Apollon : Forskningsmagasin for Universitetet i Oslo. ISSN 0803-6926. 12(3), p. 8–10. Full text in Research Archive
• Engvold, Oddbjørn (2001). Observations of prominence oscillations. Full text in Research Archive
• Engvold, Oddbjørn (2001). Solar prominence fine structure. In Murdin, Paul (Eds.), Encyclopedia of astronomy and astrophysics. IOP Publishing, Bristol ; Nature Publishing Group, London. ISSN 9780333750889. p. 2695–2698. Full text in Research Archive
• Engvold, Oddbjørn (2001). Sola og klimaforandringer, Almanakk for Norge 2002. Gyldendal Forlag. ISSN 9788205271890. p. 70–74. Full text in Research Archive Show summary

  Også på nynorsk i: Almanakk for Noreg 2002; ISBN 82-05-27190-9

• Engvold, Oddbjørn (2001). Solens innflytelse på jordens klima, Hvem, hva, hvor 2002 : Aftenpostens aktuelle oppslagsbok. Schibsted Forlag. p. 234–237. Full text in Research Archive
• Engvold, Oddbjørn (2001). Fremdeles mye uavklart om klimaendringene. Aftenposten (morgenutg. : trykt utg.). ISSN 0804-3116. p. 14–14. Full text in Research Archive
• Schmieder, Birgitte; Engvold, Oddbjørn; Wiik, J. E. & Luca, E E De (2000). Fine structure and dynamics of a filament in EUV lines: SOHO/CDS and SUMER, TRACE. Full text in Research Archive
• Hansen, Inger; Engvold, Oddbjørn; Schmieder, Birgitte; Mein, N. & Mein, P. (1999). Bright rims of solar prominences. Full text in Research Archive
• Hansen, Inger; Engvold, Oddbjørn; Schmieder, Birgitte; Mein, P.; Mein, N. & Malherbe, Jeanette [Show all 7 contributors for this article] (1999). Bright rims and dopplershifts in H alpha filaments. Full text in Research Archive
• Schmieder, Birgitte; Luca, E E De; Mein, N.; Mein, P.; Malherbe, Jeanette & Wilken, V. [Show all 9 contributors for this article] (1999). A study of hydrogen density in emerging flux loops from a coordinated TRACE and Canary Islands observation campaign. Full text in Research Archive
• Engvold, Oddbjørn; Hauge, Ø. & Maltby, Per (1999). In Memoriam: Truls S. Ringnes (1917-1999). Fra Fysikkens Verden. ISSN 0015-9247. 61(3), p. 72–72. Full text in Research Archive
• Brekke, P. & Engvold, Oddbjørn (1998). Undervurderes solens bidrag til klimavariasjonene? Energien : IFE's intern-avis. p. 10–11. Full text in Research Archive
• Pettersen, Bjørn Ragnvald & Engvold, Oddbjørn (1983). Stellar Activity. Institute of Theoretical Astrophysics. Full text in Research Archive
• Andersen, Bo Nyborg; Engvold, Oddbjørn & Pettersen, Bjørn Ragnvald (1977). An Umbral Spectrum 6812-6898 Å. Institute of Theoretical Astrophysics. Full text in Research Archive

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