Heliolatitudinal and time variations of the solar wind mass flux: Inferences from the backscattered solar Lyman‐alpha intensity maps

Katushkina, Olga; Izmodenov, Vladislav; Quémerais, Éric; Sokół, J. M.

doi:10.1002/jgra.50303

Cited by 33 publications

(29 citation statements)

References 35 publications

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“…Increasing radiation pressure or total ionization increases the size of the cavity surrounding the Sun. This model corresponds to solar conditions derived in 2009 [ Katushkina et al , ].…”

Section: Comparison To Modelmentioning

confidence: 84%

Hydrogen atoms in the inner heliosphere: SWAN‐SOHO and MASCS‐MESSENGER observations

et al. 2014

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We present here a study made by two instruments, Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and Solar Wind Anisotropy (SWAN) on SOHO that observed the interplanetary background in 2010. The combination of these two data sets allows us to perform the first study of the distribution of hydrogen atoms inside the Earth's orbit. Triangulation of the position of the maximum emissivity region (MER) was performed for the data of the Ultraviolet and Visible Spectrometer (UVVS) channel of the MASCS‐MESSENGER instrument. We find that the ecliptic longitude of the MER is 253.2°±2.0°. This is the same value that was found from the analysis of the SWAN‐SOHO H cell data obtained in 1996. This strongly suggests that the direction of the interstellar hydrogen wind has not changed between 1996 and 2010. We have also determined the distance of the MER to the Sun. We find that the volume emission rate peaks at 2.37 AU ± 0.2 AU from the Sun. This value is a good test for the solar parameters for total H ionization and radiation pressure used in models. Comparison between the two data sets obtained by the UVVS‐MASCS channel and SWAN on SOHO allow to derive the intensity between the two spacecraft at peak emission. Based on the SWAN‐SOHO calibration, we find an intensity of 80 R ± 36 R. This corresponds to a column density of 1540 m−3 AU × 2.3 ×1014m−2. When divided by the distance between the two spacecraft, we find an average number density of 2300 m−3.

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“…Increasing radiation pressure or total ionization increases the size of the cavity surrounding the Sun. This model corresponds to solar conditions derived in 2009 [ Katushkina et al , ].…”

Section: Comparison To Modelmentioning

confidence: 84%

Hydrogen atoms in the inner heliosphere: SWAN‐SOHO and MASCS‐MESSENGER observations

et al. 2014

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“…The continuous information about the latitudinal structure of the SW parameters is also essential for modeling of interstellar neutral (ISN) hydrogen (e.g. Katushkina et al, 2013Katushkina et al, , 2014Katushkina, Izmodenov, and Alexashov, 2015) and explanation of the difference between the inflow direction derived from the observations of ISN He and H and its imprint on the asymmetry of the front structure of the heliosphere. Furthermore, knowledge of the variation of the global structure of the SW provides us with information about the long-term processes on the Sun, evolution of its cycle of activity, and differences between the north and south hemispheres.…”

Section: Discussionmentioning

confidence: 99%

Reconstruction of Helio-Latitudinal Structure of the Solar Wind Proton Speed and Density

et al. 2015

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The modeling of the heliosphere requires continuous three-dimensional solar wind data. The in-situ out-of-ecliptic measurements are very rare, so that other methods of solar wind detection are needed. We use the remote-sensing data of the solar wind speed from observations of interplanetary scintillation (IPS) to reconstruct spatial and temporal structures of the solar wind proton speed from 1985 to 2013. We developed a method of filling the data gaps in the IPS observations to obtain continuous and homogeneous solar wind speed records. We also present a method to retrieve the solar wind density from the solar wind speed, utilizing the invariance of the solar wind dynamic pressure and energy flux with latitude. To construct the synoptic maps of the solar wind speed we use the decomposition into spherical harmonics of each of the Carrington rotation map. To fill the gaps in time we apply the singular spectrum analysis to the time series of the coefficients of spherical harmonics. We obtained helio-latitudinal profiles of the solar wind proton speed and density over almost three recent solar cycles. The accuracy in the reconstruction is, due to computational limitations, about 20 %. The proposed methods allow us to improve the spatial and temporal resolution of the model of the solar wind parameters presented in our previous paper (Sokół et al., Solar Phys. 285, 167, 2013) and give a better insight into the time variations of the solar wind structure. Additionally, the solar wind density is reconstructed more accurately and it fits better to the in-situ measurements from Ulysses.

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“…Below the ecliptic equator, V2 crossed the termination shock at a distance of ~84 au 4 but is still in the heliosheath. Based on Lyman-α backscatter and interstellar pickup hydrogen in the solar wind 44,45 , the interstellar neutral H-atom density at the termination shock cannot be reduced by ionization from their density in the very local interstellar medium by more than ~50% 46 . Thus, if the heliosheath is uniformly ~30 au thick, it will take the interstellar H atoms, which travel with a velocity of ~23.5 km s −1 (~5 au per year), more than 6 years to flow through the heliosheath.…”

Section: Comparison Of Inca and Lecp Channel Measurementsmentioning

confidence: 99%

The bubble-like shape of the heliosphere observed by Voyager and Cassini

et al. 2017

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For more than five decades, the shape and interactions of the heliosphere with the local interstellar medium have been discussed in the context of two competing models, posited in 1961 1 : a magnetosphere-like heliotail and a more symmetric bubble shape. Although past models broadly assumed the magnetosphere-like concept, the accurate heliospheric configuration remained largely undetermined due to lack of measurements. In recent years, however, Voyagers 1 and 2 (V1 and V2) crossed the termination shock -the boundary where the solar wind drops -north and south of the ecliptic plane at 94 au 2,3 and 84 au 4 in 2004 and 2007, respectively, and discovered the reservoir of ions and electrons that constitute the heliosheath, while Cassini remotely imaged the heliosphere 5 for the first time in 2003. Here we report 5.2-55 keV energetic neutral atom (ENA) global images of the heliosphere obtained with the Cassini/Ion and Neutral Camera (INCA). We compare them with 28-53 keV ions measured within the heliosheath by the low-energy charged particle (LECP) experiment onboard V1 and V2 over an 11-year period (2003-2014). We show that the heliosheath ions are the source of ENA. These observations also demonstrate that the heliosphere responds promptly, within ~2-3 years, to outward propagating solar wind changes in both the nose and tail directions. These results, together with the V1 measurement of a ~0.5 nT interstellar magnetic field 6 and the enhanced ratio between particle pressure and magnetic pressure in the heliosheath 7 , strongly suggest a diamagnetic bubble-like heliosphere with few substantial tail-like features. Our results are consistent with recent modelling 8-11 .Charge exchange between ions and the neutral hydrogen gas flowing through the heliosheath generates the energetic neutral atoms (ENA) that are sensed remotely by Cassini/INCA (see Methods), and enable images of the celestial sphere 12 that place the local measurements by each Voyager in a global context (see Methods). A conceptual representation of our ENA observations in a three-dimensional format, together with key heliospheric boundaries identified by the two Voyagers, is illustrated in Fig. 1a. Unlike the tail-like heliosphere model (Fig. 1b) adopted following Parker's 1961 1 calculations using a subsonic, incompressible hydrodynamic stellar wind flow (referred to henceforth as 'Parker 1'), Fig. 1a does not include an extension of the heliosphere in the heliotail ('anti-nose') direction. This resultthat is, the rough 'tail to anti-nose' symmetry in Fig. 1a -has been made possible by the correlation of 11 years of INCA ENA images and in situ V1/V2 ion measurements with the long-term variability of solar cycles 23 and 24. We infer that the heliosphere is consistent with Parker's 1961 'alternative' notion (henceforth 'Parker 2'), which presents a bubble-like structure formed under the influence of a large-scale interstellar magnetic field (depicted by the grey lines in Fig. 1a) that confines the heliosheath plasma nearly symmetrically in all directions...

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Heliolatitudinal and time variations of the solar wind mass flux: Inferences from the backscattered solar Lyman‐alpha intensity maps

Cited by 33 publications

References 35 publications

Hydrogen atoms in the inner heliosphere: SWAN‐SOHO and MASCS‐MESSENGER observations

Hydrogen atoms in the inner heliosphere: SWAN‐SOHO and MASCS‐MESSENGER observations

Reconstruction of Helio-Latitudinal Structure of the Solar Wind Proton Speed and Density

The bubble-like shape of the heliosphere observed by Voyager and Cassini

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