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Title: INTERSTELLAR GAS FLOW PARAMETERS DERIVED FROM INTERSTELLAR BOUNDARY EXPLORER-Lo OBSERVATIONS IN 2009 AND 2010: ANALYTICAL ANALYSIS

Abstract

Neutral atom imaging of the interstellar gas flow in the inner heliosphere provides the most detailed information on physical conditions of the surrounding interstellar medium (ISM) and its interaction with the heliosphere. The Interstellar Boundary Explorer (IBEX) measured neutral H, He, O, and Ne for three years. We compare the He and combined O+Ne flow distributions for two interstellar flow passages in 2009 and 2010 with an analytical calculation, which is simplified because the IBEX orientation provides observations at almost exactly the perihelion of the gas trajectories. This method allows separate determination of the key ISM parameters: inflow speed, longitude, and latitude, as well as temperature. A combined optimization, as in complementary approaches, is thus not necessary. Based on the observed peak position and width in longitude and latitude, inflow speed, latitude, and temperature are found as a function of inflow longitude. The latter is then constrained by the variation of the observed flow latitude as a function of observer longitude and by the ratio of the widths of the distribution in longitude and latitude. Identical results are found for 2009 and 2010: an He flow vector somewhat outside previous determinations ({lambda}{sub ISM{infinity}} = 79.{sup 0}0+3.{sup 0}0(-3.{sup 0}5), {beta}{sub ISM{infinity}}more » = -4.{sup 0}9 {+-} 0.{sup 0}2, V{sub ISM{infinity}} 23.5 + 3.0(-2.0) km s{sup -1}, T{sub He} = 5000-8200 K), suggesting a larger inflow longitude and lower speed. The O+Ne temperature range, T{sub O+Ne} = 5300-9000 K, is found to be close to the upper range for He and consistent with an isothermal medium for all species within current uncertainties.« less

Authors:
; ; ; ; ; ; ; ; ; ;  [1]; ;  [2];  [3]; ;  [4];  [5];  [6]
  1. Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States)
  2. Space Research Centre, Polish Academy of Sciences, Warsaw (Poland)
  3. Lockheed Martin Advanced Technology Laboratory, Palo Alto, CA (United States)
  4. Massachusetts Institute of Technology, Cambridge, MA (United States)
  5. Southwest Research Institute, San Antonio, TX (United States)
  6. Physikalisches Institut, Universitaet Bern, Bern (Switzerland)
Publication Date:
OSTI Identifier:
22048040
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal, Supplement Series
Additional Journal Information:
Journal Volume: 198; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0067-0049
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; COSMIC GASES; DATA ANALYSIS; GAS FLOW; HELIOSPHERE; HELIUM; HYDROGEN; INTERSTELLAR SPACE; NEON; OPTIMIZATION; ORIENTATION; OXYGEN; SUN; TEMPERATURE RANGE OVER 4000 K; TRAJECTORIES; VARIATIONS; VELOCITY

Citation Formats

Moebius, E, Bochsler, P, Heirtzler, D, Kucharek, H, Lee, M A, Leonard, T, Schwadron, N A, Wu, X, Petersen, L, Valovcin, D, Wurz, P, Bzowski, M, Kubiak, M A, Fuselier, S A, Crew, G, Vanderspek, R, McComas, D J, and Saul, L. INTERSTELLAR GAS FLOW PARAMETERS DERIVED FROM INTERSTELLAR BOUNDARY EXPLORER-Lo OBSERVATIONS IN 2009 AND 2010: ANALYTICAL ANALYSIS. United States: N. p., 2012. Web. doi:10.1088/0067-0049/198/2/11.
Moebius, E, Bochsler, P, Heirtzler, D, Kucharek, H, Lee, M A, Leonard, T, Schwadron, N A, Wu, X, Petersen, L, Valovcin, D, Wurz, P, Bzowski, M, Kubiak, M A, Fuselier, S A, Crew, G, Vanderspek, R, McComas, D J, & Saul, L. INTERSTELLAR GAS FLOW PARAMETERS DERIVED FROM INTERSTELLAR BOUNDARY EXPLORER-Lo OBSERVATIONS IN 2009 AND 2010: ANALYTICAL ANALYSIS. United States. doi:10.1088/0067-0049/198/2/11.
Moebius, E, Bochsler, P, Heirtzler, D, Kucharek, H, Lee, M A, Leonard, T, Schwadron, N A, Wu, X, Petersen, L, Valovcin, D, Wurz, P, Bzowski, M, Kubiak, M A, Fuselier, S A, Crew, G, Vanderspek, R, McComas, D J, and Saul, L. Wed . "INTERSTELLAR GAS FLOW PARAMETERS DERIVED FROM INTERSTELLAR BOUNDARY EXPLORER-Lo OBSERVATIONS IN 2009 AND 2010: ANALYTICAL ANALYSIS". United States. doi:10.1088/0067-0049/198/2/11.
@article{osti_22048040,
title = {INTERSTELLAR GAS FLOW PARAMETERS DERIVED FROM INTERSTELLAR BOUNDARY EXPLORER-Lo OBSERVATIONS IN 2009 AND 2010: ANALYTICAL ANALYSIS},
author = {Moebius, E and Bochsler, P and Heirtzler, D and Kucharek, H and Lee, M A and Leonard, T and Schwadron, N A and Wu, X and Petersen, L and Valovcin, D and Wurz, P and Bzowski, M and Kubiak, M A and Fuselier, S A and Crew, G and Vanderspek, R and McComas, D J and Saul, L},
abstractNote = {Neutral atom imaging of the interstellar gas flow in the inner heliosphere provides the most detailed information on physical conditions of the surrounding interstellar medium (ISM) and its interaction with the heliosphere. The Interstellar Boundary Explorer (IBEX) measured neutral H, He, O, and Ne for three years. We compare the He and combined O+Ne flow distributions for two interstellar flow passages in 2009 and 2010 with an analytical calculation, which is simplified because the IBEX orientation provides observations at almost exactly the perihelion of the gas trajectories. This method allows separate determination of the key ISM parameters: inflow speed, longitude, and latitude, as well as temperature. A combined optimization, as in complementary approaches, is thus not necessary. Based on the observed peak position and width in longitude and latitude, inflow speed, latitude, and temperature are found as a function of inflow longitude. The latter is then constrained by the variation of the observed flow latitude as a function of observer longitude and by the ratio of the widths of the distribution in longitude and latitude. Identical results are found for 2009 and 2010: an He flow vector somewhat outside previous determinations ({lambda}{sub ISM{infinity}} = 79.{sup 0}0+3.{sup 0}0(-3.{sup 0}5), {beta}{sub ISM{infinity}} = -4.{sup 0}9 {+-} 0.{sup 0}2, V{sub ISM{infinity}} 23.5 + 3.0(-2.0) km s{sup -1}, T{sub He} = 5000-8200 K), suggesting a larger inflow longitude and lower speed. The O+Ne temperature range, T{sub O+Ne} = 5300-9000 K, is found to be close to the upper range for He and consistent with an isothermal medium for all species within current uncertainties.},
doi = {10.1088/0067-0049/198/2/11},
journal = {Astrophysical Journal, Supplement Series},
issn = {0067-0049},
number = 2,
volume = 198,
place = {United States},
year = {2012},
month = {2}
}