Observations of the Interplanetary Hydrogen During Solar Cycles 23 and 24. What Can We Deduce About the Local Interstellar Medium?

Vincent, F.; Katushkina, Olga; Ben‐Jaffel, Lotfi; Harris, Walter M.; Izmodenov, Vladislav; Quémerais, Éric; Koutroumpa, Dimitra; Clarke, J. T.

doi:10.1088/2041-8205/788/2/l25

Cited by 19 publications

(19 citation statements)

References 32 publications

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“…The flow of IPH entering the solar system is estimated to be ~23 km s −1 [ Vincent et al ., , ] along the direction of 252.2° ecliptic longitude and 8.9° ecliptic latitude [ Quémerais et al ., , ; Lallement et al ., ]. The distribution and characteristics of the IPH flow, as observed along the LOS of the IUVS instrument, can subsequently vary during the MAVEN spacecraft cruise due to observing geometry, the LOS velocity vector of the moving spacecraft, as well as due to solar cycle and possible interstellar variations [ Ruciński and Bzowski , ].…”

Section: Iph Cruise Observationsmentioning

confidence: 99%

IUVS echelle‐mode observations of interplanetary hydrogen: Standard for calibration and reference for cavity variations between Earth and Mars during MAVEN cruise

et al. 2017

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The high‐resolution echelle mode of the Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile Evolution mission has been designed to measure D and H Lyman α emissions from the Martian atmosphere to obtain key information about the physical processes by which water escapes into space. Toward this goal, the absolute calibration of the instrument is critical for determining the D and H densities, the D/H ratio, and the escape flux of water. The instrument made observations of interplanetary hydrogen (IPH) along multiple look directions and conducted several postlaunch calibration campaigns during cruise as well as during orbit around Mars. The calibration efforts monitored instrument degradation and produced a consistent calibration factor at the hydrogen Lyman α wavelength (121.567 nm). The instrument was calibrated with the diffuse emission of interplanetary hydrogen (IPH) as a standard candle using measurements and model results from the Solar Wind Anisotropies (SWAN) instrument. Validation of the calibrated instrument was made by (1) comparisons to simultaneous observations of the IPH made with the lower resolution FUV mode of the IUVS instrument that were independently calibrated by using standard stars and by (2) comparisons to same‐day observations of Mars at hydrogen Lyman α made with the Hubble Space Telescope that were calculated with a radiative transfer model. Adopted FUV mode values and Hubble Space Telescope‐based model results agreed with the echelle SWAN calibrated values to within 6% and 4%, respectively. The calibrated IUVS instrument can be used to interpret emissions of atmospheric species at Mars for insights into water evolution at the planet, as well as observed IPH measurements made during cruise for further insights into dynamics of the inner heliosphere.

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Section: Iph Cruise Observationsmentioning

confidence: 99%

IUVS echelle‐mode observations of interplanetary hydrogen: Standard for calibration and reference for cavity variations between Earth and Mars during MAVEN cruise

et al. 2017

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“…To model the helium neutral gas distribution and PUI production, we take the helium temperature, density, and bulk speed in the LISM as T ∞ = 6300 K, n He = 0/015 cm − 3 , and V ∞ = 23.2 km/s . While there is an ongoing as to the best combination of interstellar flow speed and direction [ Bzowski et al ., 2012; Möbius et al ., 2012; Vincent et al, ; Katushkina et al, ; Bzowski et al, ; Lallement & Bertaux , 2014, McComas et al ., 2015; Leonard et al ., 2015]. The potential difference in the speed between 23 and 26 km/s has a negligible effect on our results.…”

Section: Kinetic Model Of Puis and Suprathermal Particlesmentioning

confidence: 99%

Modeling interstellar pickup ion distributions in corotating interaction regions inside 1 AU

et al. 2015

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We present a modeling study of interstellar pickup ion (PUI) distributions in corotating interaction regions (CIRs). We consider gradual compressions associated with CIRs formed when fast speed streams overtake slower streams in the inner heliosphere. For the analysis, we adopt a simplified magnetohydrodynamic model of a CIR. The Energetic Particle Radiation Environment Module, a parallelized particle numerical kinetic code, is used to model PUI distributions using the focused transport equation, including adiabatic cooling/heating, adiabatic focusing, and parallel and perpendicular diffusion. The continuous injection of PUIs is handled as a source term with a ring distribution in velocity space that is produced from the local neutral density obtained from a hot model of the interstellar neutral gas. The simulated distributions exhibit a harder spectrum in the compression region and a softer spectrum in the rarefaction region than that in undisturbed solar wind. As an additional result, a v À5 power law tail distribution above the PUI cutoff speed (a knee in the distribution) emerges for a particular velocity gradient in the CIR. The tail above the PUI cutoff is sensitive to the CIR velocity gradient, and in one observational case studied, this relationship adequately explains the observed spectrum from 2 to 4 times the solar wind speed. This suggests that the velocity gradient associated with the CIR formation can efficiently create a seed population of PUIs before a shock forms even without stochastic acceleration. Thus, local CIR compressions without shocks may play a significant role in the acceleration process as suggested previously. CHEN ET AL.MODELING PICKUP ION DISTRIBUTION 9269 PUBLICATIONS

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“…Primary interstellar H atoms are filtered in the heliospheric interface [see, e.g., Izmodenov et al, 1999;Izmodenov, 2007], and new secondary interstellar atoms are created by charge exchange. Therefore, measurements of backscattered solar Lyman alpha radiation in the heliosphere can be used as a remote sensing diagnostic of the interstellar H distribution as well as the properties of the heliospheric boundary [see, e.g., Bertaux et al, 1985;Hall et al, 1993;Clarke et al, 1998;Costa et al, 1999;Gangopadhyay et al, 2006;Vincent et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

“…Nowadays, Lyman alpha is measured by many instruments at the Earth orbit, e.g., SOHO/Solar Wind ANisotropy [Bertaux et al, 1995] and Hubble Space Telescope/Space Telescope Imaging Spectrograph [Woodgate et al, 1998]; closer to the Sun, e.g., around Mercury by Mercury Atmospheric and Surface Composition Spectrometer on board MErcury Surface, Space ENvironment, GEochemistry, and Ranging [McClintock and Lankton, 2007]; and in the outer heliosphere-Cassini/Ultraviolet Imaging Spectrograph [Esposito et al, 2004], New Horizons/Alice [Gladstone et al, 2013], and Voyager 1/ Journal of Geophysical Research: Space Physics 10.1002/2015JA022062 ultraviolet spectrometer (UVS) [Broadfoot et al, 1977]. These data are described and analyzed by many authors [e.g., Bertaux et al, 1997;Quémerais et al, 2008;Clarke et al, 1998;Vincent et al, 2014;Quémerais et al, 2014;Pryor et al, 2008;Gladstone et al, 2013;Lallement et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

Remote diagnostic of the hydrogen wall through measurements of the backscattered solar Lyman alpha radiation by Voyager 1/UVS in 1993–2003

et al. 2016

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We perform a new analysis of the Lyman alpha data obtained by Voyager 1 during the spatial scans in 1993–2003 while Voyager 1 was at 53–88 AU from the Sun. These data are the important source of information on the hydrogen distribution in the outer heliosphere. A sophisticated global kinetic‐MHD model of the heliospheric interface and a radiative transfer model are used for the analysis. It is shown for the first time that the ratio of the Lyman alpha intensities detected in the downwind and upwind lines of sight in the outer heliosphere is sensitive to the configuration (peak value and location) of the hydrogen wall. The hydrogen wall is a source of Doppler‐shifted backscattered Lyman alpha photons, so it can be seen from inside the heliosphere. Therefore, Voyager 1/ultraviolet spectrometer (UVS) Lyman alpha data can be used for remote sensing of the hydrogen wall. We show that our current global model of the outer heliosphere, which is consistent with many other measurements including Lyman alpha data from both Voyager 1 and 2 in 1980–1993, provides a systematically larger downwind to upwind intensity ratio compared with the UVS data in 1993–2003. In order to decrease the ratio, a higher and/or closer hydrogen wall is needed.

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Observations of the Interplanetary Hydrogen During Solar Cycles 23 and 24. What Can We Deduce About the Local Interstellar Medium?

Abstract: The whole set has been compared to physically realistic models to test both sets of LISM physical parameters as measured by Ulysses and IBEX, respectively. This comparison shows that the LISM velocity vector has not changed significantly since Ulysses measurements.

Cited by 19 publications

References 32 publications

IUVS echelle‐mode observations of interplanetary hydrogen: Standard for calibration and reference for cavity variations between Earth and Mars during MAVEN cruise

IUVS echelle‐mode observations of interplanetary hydrogen: Standard for calibration and reference for cavity variations between Earth and Mars during MAVEN cruise

Modeling interstellar pickup ion distributions in corotating interaction regions inside 1 AU

Remote diagnostic of the hydrogen wall through measurements of the backscattered solar Lyman alpha radiation by Voyager 1/UVS in 1993–2003

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