The IBEX Flight Segment

Kubiak

Möbius

et al. 2012

ApJS

Self Cite

154

295

Because of its high ionization potential and weak interaction with hydrogen, Neutral Interstellar Helium is almost unaffected at the heliospheric interface with the interstellar medium and freely enters the solar system. This second most abundant species provides some of the best information on the characteristics of the interstellar gas in the Local Interstellar Cloud. The Interstellar Boundary Explorer (IBEX) is the second mission to directly detect NISHe. We present a comparison between recent IBEX NISHe observations and simulations carried out using a well-tested quantitative simulation code. Simulation and observation results compare well for times when measured fluxes are dominated by NISHe (and contributions from other species are small). Differences between simulations and observations indicate a previously undetected secondary population of neutral helium, likely produced by interaction of interstellar helium with plasma in the outer heliosheath. Interstellar neutral parameters are statistically different from previous in situ results obtained mostly from the GAS/Ulysses experiment, but they do agree with the local interstellar flow vector obtained from studies of interstellar absorption: the newlyestablished flow direction is ecliptic longitude 79.2 • , latitude −5.1 • , the velocity is ∼ 22.8 kms −1 , and the temperature is 6200 K. These new results imply a markedly lower absolute velocity of the gas and thus significantly lower dynamic pressure on the boundaries of the heliosphere and different orientation of the Hydrogen Deflection Plane compared to prior results from Ulysses. A different orientation of this plane also suggests a new geometry of the interstellar magnetic field and the lower dynamic pressure calls for a compensation by other components of the pressure balance, most likely a higher density of interstellar plasma and strength of interstellar magnetic field.

Section: Collimator-averaged Signal As Function Of Spin Phasementioning

confidence: 99%

NEUTRAL INTERSTELLAR HELIUM PARAMETERS BASED ON IBEX-Lo OBSERVATIONS AND TEST PARTICLE CALCULATIONS

Kubiak

Möbius

et al. 2012

ApJS

Self Cite

154

295

“…The orientation of the Z-axis is periodically changed to approximately follow the Sun. Originally, the orientation of the spin-axis was modified after the perigee in each orbit (Scherrer et al 2009). After orbit 127 in 2011 June, IBEX was placed into a long-term stable lunar-resonance orbit (McComas et al 2011) and since then the IBEX spin-axis has been re-oriented twice per orbit, near apogee and perigee.…”

Section: Strategy Of Isn Observations By Ibexmentioning

confidence: 99%

INTERSTELLAR NEUTRAL HELIUM IN THE HELIOSPHERE FROM IBEX OBSERVATIONS. I. UNCERTAINTIES AND BACKGROUNDS IN THE DATA AND PARAMETER DETERMINATION METHOD

Swaczyna

Kubiak

et al. 2015

ApJS

Self Cite

This paper is one of three companion papers presenting the results of our in-depth analysis of the interstellar neutral helium (ISN He) observations carried out using the IBEX-Lo during the first six Interstellar Boundary Explorer (IBEX ) observation seasons. We derive corrections for losses due to the limited throughput of the interface buffer and determine the IBEX spin-axis pointing. We develop an uncertainty system for the data, taking into account the resulting correlations between the data points. This system includes uncertainties due to Poisson statistics, background, spin-axis determination, systematic deviation of the boresight from the prescribed position, correction for the interface buffer losses, and the expected Warm Breeze (WB) signal. Subsequently, we analyze the data from 2009 to examine the role of various components of the uncertainty system. We show that the ISN He flow parameters are in good agreement with the values obtained by the original analysis. We identify the WB as the principal contributor to the global χ 2 values in previous analyses. Other uncertainties have a much milder role and their contributions are comparable to each other. The application of this uncertainty system reduced the minimum χ 2 value 4-fold. The obtained χ 2 value, still exceeding the expected value, suggests that either the uncertainty system may still be incomplete or the adopted physical model lacks a potentially important element, which is likely an imperfect determination of the WB parameters. The derived corrections and uncertainty system are used in the accompanying paper by Bzowski et al. in an analysis of the data from six seasons.

“…Space Mission Capabilities (15) First use of additional Solid Rocket Motor on Pegasus LV and spacecraft propulsion to achieve very high altitude orbit. McComas et al 2009a;Scherrer et al 2009 (16) Discovery and first use of long-term stable lunar synchronous orbit.…”

Section: Mccomas Et Al 2009bmentioning

confidence: 99%

“…The Interstellar Boundary Explorer (IBEX) is the first, and thus far only, mission dedicated to imaging and understanding the interaction of our heliosphere with the local interstellar medium (LISM; see McComas et al 2009a and other papers in the IBEX Special Issue of Space Science Reviews). IBEX was launched on 2008 October 19, and after roughly two months of orbit raising to place it into its initial highly elliptical orbit (apogee ∼50 Earth radii; McComas et al 2009a;Scherrer et al 2009), began returning the first global observations of this interaction through measurements of energetic neutral atoms (ENAs).…”

Section: Introductionmentioning

confidence: 99%

IBEX : THE FIRST FIVE YEARS (2009-2013)

McComas

Allegrini

et al. 2014

ApJS

Self Cite

The Interstellar Boundary Explorer (IBEX) returned its first five years of scientific observations from 2009 to 2013. In this study, we examine, validate, initially analyze, and provide to the broad scientific community this complete set of energetic neutral atom (ENA) observations for the first time. IBEX measures the fluxes of ENAs reaching 1 AU from sources in the outer heliosphere and most likely the very nearby interstellar space beyond the heliopause. The data, maps, and documentation provided in this study represent the fourth major release of the IBEX data, incorporate important improvements, and should be used for future studies and as the citable reference for the current version of the IBEX data. In this study, we also examine five years of time evolution in the outer heliosphere and the resulting ENA emissions. These observations show a complicated variation with a general decrease in ENA fluxes from 2009 to 2012 over most regions of the sky, consistent with a 2-4 year recycle time for the previously decreasing solar wind flux. In contrast, the heliotail fluxes continue to decrease, again consistent with a significantly more distant source in the downwind direction. Finally, the Ribbon shows the most complicated time variations, with a leveling off in the southern hemisphere and continued decline in the northern one; these may be consistent with the Ribbon source being significantly farther away in the north than in the south. Together, the observations and results shown in this study expose the intricacies of our heliosphere's interaction with the local interstellar medium.