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  First light observations of the solar wind in the outer corona with the Metis coronagraph

Romoli, M., Antonucci, E., Andretta, V., Capuano, G. E., Da Deppo, V., De Leo, Y., et al. (2021). First light observations of the solar wind in the outer corona with the Metis coronagraph. Astronomy and Astrophysics, 656: A32. doi:10.1051/0004-6361/202140980.

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Romoli, M., Author
Antonucci, E., Author
Andretta, V., Author
Capuano, G. E., Author
Da Deppo, V. , Author
De Leo, Yara1, Author              
Downs, C., Author
Fineschi, S., Author
Heinzel, P., Author
Landini, F., Author
Liberatore, A., Author
Naletto, G., Author
Nicolini, G., Author
Pancrazzi, M., Author
Sasso, C., Author
Spadaro, D., Author
Susino, R., Author
Telloni, D., Author
Teriaca, Luca1, Author              
Uslenghi, M., Author
Wang, Y.-M., AuthorBemporad, A., AuthorCapobianco, G., AuthorCasti, M., AuthorFabi, M., AuthorFrassati, F., AuthorFrassetto, F., AuthorGiordano, S., AuthorGrimani, C., AuthorJerse, G., AuthorMagli, E., AuthorMassone, G., AuthorMesserotti, M., AuthorMoses, D., AuthorPelizzo, M.-G., AuthorRomano, P., AuthorSchühle, Udo1, Author              Slemer, A., AuthorStangalini, M., AuthorStraus, T., AuthorVolpicelli, C. A., AuthorZangrilli, L., AuthorZuppella, P., AuthorAbbo, L., AuthorAuchère, F., AuthorAznar Cuadrado, Regina1, Author              Berlicki, A., AuthorBruno, R., AuthorCiaravella, A., AuthorD’Amicis, R., AuthorLamy, P., AuthorLanzafame, A., AuthorMalvezzi, A. M., AuthorNicolosi, P., AuthorNisticò, G., AuthorPeter, Hardi1, Author              Plainaki, C., AuthorPoletto, L., AuthorReale, F., AuthorSolanki, Sami K.1, Author              Strachan, L., AuthorTondello, G., AuthorTsinganos, K., AuthorVelli, M., AuthorVentura, R., AuthorVial, J.-C., AuthorWoch, Joachim1, Author              Zimbardo, G., Author more..
1Department Sun and Heliosphere, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832289              


Free keywords: Sun: corona / solar wind / Sun: UV radiation
 Abstract: In this work, we present an investigation of the wind in the solar corona that has been initiated by observations of the resonantly scattered ultraviolet emission of the coronal plasma obtained with UVCS-SOHO, designed to measure the wind outflow speed by applying Doppler dimming diagnostics. Metis on Solar Orbiter complements the UVCS spectroscopic observations that were performed during solar activity cycle 23 by simultaneously imaging the polarized visible light and the H I Lyman-α corona in order to obtain high spatial and temporal resolution maps of the outward velocity of the continuously expanding solar atmosphere. The Metis observations, taken on May 15, 2020, provide the first H I Lyman-α images of the extended corona and the first instantaneous map of the speed of the coronal plasma outflows during the minimum of solar activity and allow us to identify the layer where the slow wind flow is observed. The polarized visible light (580–640 nm) and the ultraviolet H I Lyα (121.6 nm) coronal emissions, obtained with the two Metis channels, were combined in order to measure the dimming of the UV emission relative to a static corona. This effect is caused by the outward motion of the coronal plasma along the direction of incidence of the chromospheric photons on the coronal neutral hydrogen. The plasma outflow velocity was then derived as a function of the measured Doppler dimming. The static corona UV emission was simulated on the basis of the plasma electron density inferred from the polarized visible light. This study leads to the identification, in the velocity maps of the solar corona, of the high-density layer about ±10° wide, centered on the extension of a quiet equatorial streamer present at the east limb – the coronal origin of the heliospheric current sheet – where the slowest wind flows at about 160 ± 18 km s−1 from 4 R to 6 R. Beyond the boundaries of the high-density layer, the wind velocity rapidly increases, marking the transition between slow and fast wind in the corona.


Language(s): eng - English
 Dates: 2021
 Publication Status: Published online
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1051/0004-6361/202140980
 Degree: -



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Title: Astronomy and Astrophysics
  Other : Astron. Astrophys.
Source Genre: Journal
Publ. Info: Les Ulis Cedex A France : EDP Sciences
Pages: - Volume / Issue: 656 Sequence Number: A32 Start / End Page: - Identifier: ISSN: 1432-0746
ISSN: 0004-6361
CoNE: https://pure.mpg.de/cone/journals/resource/954922828219_1