Global helium abundance measurements in the solar corona

Moses, J. D.; Antonucci, E.; Newmark, Jeffrey; Auchère, F.; Fineschi, Silvano; Romoli, M.; Telloni, Daniele; Massone, G.; Zangrilli, L.; Focardi, M.; Landini, Federico; Pancrazzi, M.; Rossi, G.; Malvezzi, Andrea Marco; Wang, Dennis; Leclec'h, Jean-Christophe; Moalic, Jean‐Pierre; Rouesnel, F.; Abbo, L.; Canou, A.; Barbey, Nicolas; Guennou, C.; Laming, J. M.; Lemen, J. R.; Wüelser, Jean-Pierre; Kohl, J. L.; Gardner, L. D.

doi:10.1038/s41550-020-1156-6

Cited by 33 publications

(39 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Specifically, the electron density is derived by applying the inversion technique developed by van de Hulst (1950) and based on fitting pB data with a polynomial function (red line in Figure 3(c)). These values are reported in Figure 4(a) (black diamonds) along with a polynomial fit (red line) extrapolated to the PSP location: the very good agreement with the PSP measurement (green diamond: n e,PSP = n p,PSP /0.95, assuming a fully ionized plasma with 2.5% helium, according to Moses et al 2020) corroborates the fact that the same element of plasma is indeed followed from the coronal region, where it is undergoing acceleration during its outward propagation, to the PSP position in the very inner heliosphere. The radial component of the coronal wind velocity on the POS is obtained by the Doppler dimming technique applied to a 3D solar coronal modeled on the basis of the so-inferred electron density and the measured UV H I Lyα intensity (the reader is referred to Antonucci et al 2020b;Romoli et al 2021, for an exhaustive review on how to infer outflow velocities from UV radiative lines observed in the expanding corona and for the Metis first light observations of the coronal solar wind, respectively), under the following assumptions: The coronal solar wind velocity undergoes a rapid increase with heliocentric distance, from ∼80 to ∼150 km s −1 , in the range from 3.5 to 4.5 R e .…”

Section: Analysis and Resultsmentioning

confidence: 55%

See 1 more Smart Citation

Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter–Parker Solar Probe Quadrature

Telloni

Andretta

Antonucci

et al. 2021

ApJL

Self Cite

View full text Add to dashboard Cite

This Letter addresses the first Solar Orbiter (SO)-Parker Solar Probe (PSP) quadrature, occurring on 2021 January 18 to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in the corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source region from where it originated. Thanks to the close approach of PSP to the Sun and the simultaneous Metis observation of the solar corona, the flow-aligned magnetic field and the bulk kinetic energy flux density can be empirically inferred along the coronal current sheet with an unprecedented accuracy, allowing in particular estimation of the Alfvén radius at 8.7 solar radii during the time of this event. This is thus the very first study of the same solar wind plasma as it expands from the sub-Alfvénic solar corona to just above the Alfvén surface.

show abstract

Section: Analysis and Resultsmentioning

confidence: 55%

“…It is worth noting that the above estimates have been inferred assuming a helium abundance of 2.5% (Moses et al 2020). This value can be considered a lower limit (in fact, it refers to a particularly weak solar minimum).…”

Section: Analysis and Resultsmentioning

confidence: 94%

Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter–Parker Solar Probe Quadrature

Telloni

Andretta

Antonucci

et al. 2021

ApJL

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the northern hemisphere of the corona observed during the Skylab period and studied by Munro and Jackson (1977), approximately 60% of the entire atmosphere above 3 R was found to be connected to about 8% of the solar surface, that is, in polar coronal holes magnetic field lines were found to be super-radial, and the increase of the polar hole's crosssectional area from the surface to 3 R turned out to be about 7 times greater than if the boundary were purely radial.…”

Section: Outflow Speed and Magnetic Field Topologymentioning

confidence: 99%

“…In 2009, during the solar minimum of cycle 23, the first measurements of He II 30.4 nm line intensity, combined with simultaneous measurement of the H I line, were obtained over the west limb of the Sun out to 2.2 R with the Sounding-rocket CORonagraph Experiment (SCORE), during the first flight of the HElium Resonance Scattering in the Corona and HELiosphere (HERSCHEL) sounding rocket (Moses et al 2020). This investigation led to the conclusion that, as in the case of oxygen, the helium abundance in the outer corona is influenced by the topology of the magnetic field lines.…”

Section: Elemental Abundances In the Coronal Windmentioning

confidence: 99%

Observations of the Solar Corona from Space

et al. 2020

Self Cite

View full text Add to dashboard Cite

Space observations of the atmosphere of the Sun, obtained in half a century of dedicated space missions, provide a well established picture of the medium and large-scale solar corona, which is highly variable with the level of solar activity through a solar cycle and evolves with the long-term evolution of the magnetic cycles. In this review, we summarize the physical properties and dynamics of the medium and large-scale corona, consisting primarily of active regions, streamers and coronal holes; describe the dependence of coronal patterns on the magnetic field patterns changing through the solar cycle and the properties of the regions of open magnetic flux channeling the solar wind; the ubiquitous presence of fluctuations in the outer corona; the rotational properties of the large-scale corona; and the persistent hemispheric asymmetries in the emergence of magnetic fields and the distribution of the coronal emission.

show abstract

“…In coronal holes associated with the sources of the fast solar wind, the protons and ions are observed to be hotter than electrons and anisotropic, demonstrating the importance of anisotropic proton and heavier ion heating (e.g., Kohl et al 1997;Cranmer et al 1999;Hahn & Savin 2013;Jeffrey et al 2018). Moreover, α particles are typically hotter and faster than protons in the fast SW (e.g., Marsch et al 1982b;Borovsky & Gary 2014;Ďurovcová et al 2019b,a) and could indicate the SW source regions (Ofman 2004;Giordano et al 2007;Ofman & Kramar 2010;Abbo et al 2016;Moses et al 2020). The relative abundance of α particles in the solar wind varies considerably with the wind type and the solar cycle (e.g., Kasper et al 2007;Ďurovcová et al 2017;Alterman & Kasper 2019).…”

Section: Introductionmentioning

confidence: 99%

Modeling ion beams, kinetic instabilities, and waves observed by the Parker Solar Probe near perihelia

Ofman,

Boardsen,

Jian

et al. 2021

Preprint

View full text Add to dashboard Cite

Recent in-situ observations from the Parker Solar Probe (PSP) mission in the inner heliosphere near perihelia show evidence of ion beams, temperature anisotropies, and kinetic wave activity, which are likely associated with kinetic heating and acceleration processes of the solar wind. In particular, the proton beams were detected by PSP/SPAN-I and related magnetic fluctuation spectra associated with ion-scale waves were observed by the FIELDS instrument. We present the ion velocity distribution functions (VDFs) from SPAN-I and the results of 2.5D and 3D hybrid-particle-in-cell (hybrid-PIC) models of proton and α particle super-Alfvénic beams that drive ion kinetic instabilities and waves in the inner-heliospheric solar wind. We model the evolution of the ion VDFs with beams, ion relative drifts speeds, and ion temperature anisotropies for solar wind conditions near PSP perihelia. We calculate the partition of energies between the particles (ions) along and perpendicular to the magnetic field, as well as the evolution of magnetic energy and compare to observationally deduced values. We conclude that the ion beam driven kinetic instabilities in the solar wind plasma near perihelia are important components in the cascade of energy from fluid to kinetic scale, an important component in the solar wind plasma heating process.

show abstract

Global helium abundance measurements in the solar corona

Cited by 33 publications

References 43 publications

Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter–Parker Solar Probe Quadrature

Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter–Parker Solar Probe Quadrature

Observations of the Solar Corona from Space

Modeling ion beams, kinetic instabilities, and waves observed by the Parker Solar Probe near perihelia

Contact Info

Product

Resources

About