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UID:157@atst.osups.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20260625T170000
DTEND;TZID=Europe/Paris:20260625T180000
DTSTAMP:20260622T212205Z
URL:https://atst.osups.universite-paris-saclay.fr/calendrier/issi-webinar-
 marco-velli/
SUMMARY:ISSI webinar by Marco Velli:  Origins and Structure of the Heliosph
 ere: Novel Discoveries and Insights from Parker Solar Probe and Solar Orbi
 ter
DESCRIPTION:\n\n\n\n\n\nMarco Velli will give the ISSI Game Changers webina
 r of the 25th of June 2026. Please click here for the Zoom session (meetin
 g ID: 852 6990 9362\, password: 459004)\, or see the webinar web page.\n\n
 \n\n\n\n\n\n\n\n\n\n\nAbstract: It has been established since the early o
 bservations by Helios (and later confirmed by Ulysses and SOHO) that the s
 ources of fast solar wind streams at solar minimum are polar coronal holes
 . In contrast\, slower solar wind streams have contributions from differen
 t sources. The larger than expected filling factor of slow solar wind has 
 been attributed\, in addition to flows surrounding the Heliospheric curren
 t sheet\, to flows coming from coronal hole boundaries\, i.e.\, regions wi
 th large expansion factors\, or from regions where the mapping of the magn
 etic field from the photosphere into the heliosphere is complex\, as ident
 ified for example by the squashing factor. This is known as the S-Web. The
  ubiquity of Alfvénic fluctuations in the inner Heliosphere\, and the fre
 quent observation of slow Alfvénic solar wind by Parker Solar Probe as we
 ll as Solar Orbiter\, previously observed relatively rarely in Helios and 
 Wind data\, provide evidence for a picture of solar wind origins that inco
 rporates both the expansion factor and S-web paradigms: both coronal holes
  with large expansion and S-Web regions act as slow sources of the solar w
 ind\, with the difference that highly expanding coronal holes provide Alfv
 énic slow streams\, while the S-web wind is unlikely to exhibit strong Al
 fvénic correlations. Over the solar cycle the distribution of solar wind 
 flows changes\, and we will highlight how observations from Parker Solar P
 robe and Solar Orbiter have opened new perspectives on how the solar magne
 tic field is advected into the Heliosphere.\n\n\n\n\n\n
CATEGORIES:Séminaires et soutenances de thèse/HDR
LOCATION:https://www.issibern.ch/origins-and-structure-of-the-heliosphere-n
 ovel-discoveries-and-insights-from-parker-solar-probe-and-solar-orbiter/
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