Width and Variation of the ENA Flux Ribbon Observed by the Interstellar Boundary Explorer

Fuselier, S. A.; Allegrini, F.; Funsten, H. O.; Ghielmetti, A. G.; Heirtzler, D.; Kucharek, H.; Lennartsson, O. W.; McComas, D. J.; Möbius, E.; Moore, T. E.; Petrinec, S. M.; Saul, L.; Scheer, J.; Schwadron, N. A.; Würz, Peter

doi:10.1126/science.1180981

Cited by 165 publications

(127 citation statements)

References 9 publications

Supporting

Mentioning

121

Contrasting

Order By: Relevance

“…The unexpected, yet defining feature in this first sky map (and in subsequent maps as well) was a Ribbon of neutral fluxes oriented approximately perpendicular to an independent estimate of the direction of the interstellar magnetic field (McComas et al 2009a;Schwadron et al 2009;Funsten et al 2009b). This Ribbon extends over the energy range from about 0.2 keV to 6 keV and is superposed on a more uniform, globally distributed flux (McComas et al 2009c;Fuselier et al 2009a;Schwadron et al 2011).…”

Section: Introductionmentioning

confidence: 96%

“…With some important exceptions (e.g., McComas et al 2009b;Fuselier et al 2009a), most of the initial and subsequent results from the mission focus on the IBEX-Hi energy range from about 0.5 to 6 keV. For the globally distributed flux, the dominant parent ion source for neutrals in the energy range above 1 keV is likely ions that were originally picked up in the heliosphere before the solar wind encountered the termination shock (e.g., Gruntman et al 2001;Prested et al 2008;Gloeckler & Fisk 2010).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

HELIOSPHERIC NEUTRAL ATOM SPECTRA BETWEEN 0.01 AND 6 keV FROMIBEX

Fuselier

Allegrini

Bzowski

et al. 2012

ApJ

Self Cite

View full text Add to dashboard Cite

Since 2008 December, the Interstellar Boundary Explorer (IBEX) has been making detailed observations of neutrals from the boundaries of the heliosphere using two neutral atom cameras with overlapping energy ranges. The unexpected, yet defining feature discovered by IBEX is a Ribbon that extends over the energy range from about 0.2 to 6 keV. This Ribbon is superposed on a more uniform, globally distributed heliospheric neutral population. With some important exceptions, the focus of early IBEX studies has been on neutral atoms with energies greater than ∼0.5 keV. With nearly three years of science observations, enough low-energy neutral atom measurements have been accumulated to extend IBEX observations to energies less than ∼0.5 keV. Using the energy overlap of the sensors to identify and remove backgrounds, energy spectra over the entire IBEX energy range are produced. However, contributions by interstellar neutrals to the energy spectrum below 0.2 keV may not be completely removed. Compared with spectra at higher energies, neutral atom spectra at lower energies do not vary much from location to location in the sky, including in the direction of the IBEX Ribbon. Neutral fluxes are used to show that low energy ions contribute approximately the same thermal pressure as higher energy ions in the heliosheath. However, contributions to the dynamic pressure are very high unless there is, for example, turbulence in the heliosheath with fluctuations of the order of 50-100 km s −1 .

show abstract

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

HELIOSPHERIC NEUTRAL ATOM SPECTRA BETWEEN 0.01 AND 6 keV FROMIBEX

Fuselier

Allegrini

Bzowski

et al. 2012

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…Detecting energetic neutral atoms (ENAs) generated in the outer heliosphere provides a new window into the otherwise inaccessible plasma physics at the borders of the solar system. Since the first release of the IBEX data (McComas et al 2009a;Schwadron et al 2009;Funsten et al 2009;Fuselier et al 2009), it became obvious that essentially all existing models of the heliospheric interface disagreed with the new observational data. Many new models, ideas and concepts related to the outer heliosphere have been put forward since (see e.g.…”

Section: Introductionmentioning

confidence: 99%

Transit-time aspects of ENA production models for the inner heliosheath

Siewert

Fahr

McComas

2014

A&A

Self Cite

View full text Add to dashboard Cite

It is still a major challenge to understand the data of energetic neutral atoms (ENAs) that arrive from the outer heliosphere. These data are provided by the IBEX mission. With the most recent data covering three years of dynamical evolution, it is now possible to study temporal correlations with the solar cycle. We present in this paper for the first time an extended study dedicated to the transit-time delay between the plasma that is ejected from the Sun towards the outer heliosphere and the ENA fluxes that reach the detector after the solar wind protons undergo charge exchange processes in their distant production regions in the inner heliosheath. We derive transit-time delays caused by both general and non-trivial model-dependent contributions for arbitrary points in the inner heliosheath. In addition, we also calculate the average transit-time delay along the line-of-sight in selected directions, allowing to estimate how strongly an extended emission region can reduce the resolution that is possible with transit-time studies. We are able to demonstrate that ENAs generated beyond a certain characteristic streamline distance are mostly removed by charge exchange, and thus do not contribute significantly to the keV-ENA fluxes observed by IBEX. For this reason, transit-time delays do provide a viable tool for studying the impact of the solar cycle on ENA fluxes.

show abstract

“…The first global IBEX observations (McComas et al 2009b;Fuselier et al 2009;Funsten et al 2009a;Schwadron et al 2009) revealed a narrow Ribbon of ENA emission, 2-3 times brighter than the global distribution of ENAs. This Ribbon is only ∼20 • in width, but extends over the sky (being brighter along a ∼300 • arc across the sky).…”

Section: Introductionmentioning

confidence: 99%

FIRST SKY MAP OF THE INNER HELIOSHEATH TEMPERATURE USINGIBEXSPECTRA

Livadiotis

McComas

Dayeh

et al. 2011

ApJ

Self Cite

106

View full text Add to dashboard Cite

Analysis of the IBEX-Hi Energetic Neutral Atom spectra reveals, for the first time, the sky map of the source ion temperatures. The solar wind exists in non-equilibrium stationary states and can be described by kappa distributions. The high-energy asymptotic behavior of kappa distributions leads to a power law of the flux versus energy spectrum, while its specific formulation derives the temperature and kappa index that govern these distributions. We find that the observed temperature in most directions is about a million degrees, in agreement with most heliospheric models for the inner heliosheath. Thus, the termination shock is stronger in most places than revealed by the Voyagers' observations at their two unique crossing points. The global sky maps indicate low-temperature regions in various directions, including toward Voyager 2 where the temperature is an order of magnitude lower, consistent with in situ Voyager observations. Interestingly, the vast majority of measured kappa indices are between ∼1.5 and ∼2.5, consistent with the far-equilibrium "cavity" of minimum entropy discovered by Livadiotis & McComas. The sky maps suggest that the Ribbon is a string of localized regions, while its thermodynamical behavior differentiates it from the global distributed flux. A simple model is developed to derive the density, heliosheath thickness, and thermal pressure. We find that the Ribbon thermal pressure is ∼3.5 pDyn cm −2 , roughly equal to the mechanical pressure exerted by the Local Interstellar Medium.

show abstract

Width and Variation of the ENA Flux Ribbon Observed by the Interstellar Boundary Explorer

Cited by 165 publications

References 9 publications

HELIOSPHERIC NEUTRAL ATOM SPECTRA BETWEEN 0.01 AND 6 keV FROMIBEX

HELIOSPHERIC NEUTRAL ATOM SPECTRA BETWEEN 0.01 AND 6 keV FROMIBEX

Transit-time aspects of ENA production models for the inner heliosheath

FIRST SKY MAP OF THE INNER HELIOSHEATH TEMPERATURE USINGIBEXSPECTRA

Contact Info

Product

Resources

About