@article{f13fb28d56734e27a3c40c4a16f1c16f,
title = "Oblique and rippled heliosphere structures from the Interstellar Boundary Explorer",
abstract = "Past analysis has shown that the heliosphere structure can be deduced from correlations between long-scale solar wind pressure evolution and energetic neutral atom emissions. However, this required spatial and temporal averaging that smoothed out small or dynamic features of the heliosphere. In late 2014, the solar wind dynamic pressure increased by roughly 50% over a period of 6 months, causing a time and directional-dependent rise in around 2–6 keV energetic neutral atom fluxes from the heliosphere observed by the Interstellar Boundary Explorer. Here, we use the 2014 pressure enhancement to provide a simultaneous derivation of the three-dimensional heliospheric termination shock (HTS) and heliopause (HP) distances at high resolution from Interstellar Boundary Explorer measurements. The analysis reveals rippled HTS and HP surfaces that are oblique with respect to the local interstellar medium upwind direction, with significant asymmetries in the heliosphere structure compared to steady-state heliosphere models. We estimate that the heliosphere boundaries contain roughly ten astronomical unit-sized spatial variations, with slightly larger variations on the HTS surface than the HP and a large-scale, southwards-directed obliquity of the surfaces in the meridional plane. Comparisons of the derived HTS and HP distances with Voyager observations indicate substantial differences in the heliosphere boundaries in the northern versus southern hemispheres and their motion over time.",
author = "Zirnstein, {Eric J.} and Shrestha, {Bishwas L.} and McComas, {David J.} and Dayeh, {Maher A.} and Jacob Heerikhuisen and Reisenfeld, {Daniel B.} and Sok{\'o}{\l}, {Justyna M.} and Pawe{\l} Swaczyna",
note = "Funding Information: E.J.Z. acknowledges support from NASA grant nos. 80NSSC18K1212, 80NSSC20K0783 and 80NSSC21K1686. E.J.Z., B.L.S., D.J.M., M.A.D., D.B.R., J.M.S. and P.S. acknowledge support from the IBEX mission as a part of NASA{\textquoteright}s Explorer Program (grant no. 80NSSC20K0719). E.J.Z., D.J.M., M.A.D. and D.B.R. also acknowledge support from the IMAP mission as a part of NASA{\textquoteright}s Solar Terrestrial Probes mission line (80GSFC19C0027). D.B.R. acknowledges support by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project no. 20220107DR. The SW speed data from IPS observations come from the Solar Wind Group, ISEE, Nagoya University ( https://stsw1.isee.nagoya-u.ac.jp/ips_data-e.html ). E.J.Z. and J.M.S. thank Munetoshi Tokumaru for helpful discussions about the IPS data. E.J.Z. also thanks Paul Janzen for helpful discussions about IBEX-Hi data. Funding Information: E.J.Z. acknowledges support from NASA grant nos. 80NSSC18K1212, 80NSSC20K0783 and 80NSSC21K1686. E.J.Z., B.L.S., D.J.M., M.A.D., D.B.R., J.M.S. and P.S. acknowledge support from the IBEX mission as a part of NASA{\textquoteright}s Explorer Program (grant no. 80NSSC20K0719). E.J.Z., D.J.M., M.A.D. and D.B.R. also acknowledge support from the IMAP mission as a part of NASA{\textquoteright}s Solar Terrestrial Probes mission line (80GSFC19C0027). D.B.R. acknowledges support by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project no. 20220107DR. The SW speed data from IPS observations come from the Solar Wind Group, ISEE, Nagoya University (https://stsw1.isee.nagoya-u.ac.jp/ips_data-e.html). E.J.Z. and J.M.S. thank Munetoshi Tokumaru for helpful discussions about the IPS data. E.J.Z. also thanks Paul Janzen for helpful discussions about IBEX-Hi data. Publisher Copyright: {\textcopyright} 2022, The Author(s).",
year = "2022",
month = dec,
doi = "10.1038/s41550-022-01798-6",
language = "English (US)",
volume = "6",
pages = "1398--1413",
journal = "Nature Astronomy",
issn = "2397-3366",
publisher = "Nature Publishing Group",
number = "12",
}