Abstract
The solar wind carves out a cavity, known as the heliosphere, in the warm local interstellar cloud, which is itself embedded in a larger hot cloud. It is generally assumed that there is an overall pressure balance between these three regions. Thermal pressure and magnetic field pressure in the local interstellar cloud should therefore balance the inward pressure from the hot cloud1–3, and determine the size of the heliosphere. Here we present direct measurements of the density and speed of interstellar hydrogen and helium ions deep inside the Solar System, from which we derive the thermal pressure in the local interstellar cloud. Combined with the fact that the magnetic field strength in the local cloud is constrained to be less than 4.3 µG (to be compatible with the fact that the Voyager 1 spacecraft has yet to encounter the heliosphere termination shock), the total pressure that we infer is insufficient to balance the inward pressure from the hot cloud. We conclude that either the magnetic field in the local cloud is inhomogeneous, or there is a significant, as yet undetected, non-thermal component to the pressure in the local cloud.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Bowyer, S., Lieu, R., Sidher, S. D., Lampton, M. & Kunde, J. Nature 375, 212–214 (1995).
Cox, D. Nature 375, 185–186 (1995).
Cox, D. P. & Reynolds, R. J. Annu. Rev. Astron. Astrophys. 25, 303–344 (1987).
Möbius, E. et al. Nature 318, 426–429 (1985).
Gloeckler, G. et al. Science 261, 70–73 (1993).
Gloeckler, G. & Geiss, J. Nature 381, 210–212 (1996).
Gloeckler, G. in Proc. 1st ISSI Workshop (eds von Steiger, R., Lallement, R. & Lee, M. A.) Space Sci. Rev. 78, 335–346 (1996).
Holzer, T. E. Annu. Rev. Astron. Astrophys. 27, 199–234 (1989).
Baranov, V. B. & Malama, Y. G. J. Geophys. Res. 100, 755–761 (1995).
Williams, L. L., Hall, D. T., Pauls, H. L. & Zank, G. P. Astrophys. J. (submitted).
Steinolfson, R. S. & Gurnett, D. A. Geophys. Res. Lett. 22, 651–654 (1995).
Gloeckler, G. et al. Astron. Astrophys. Suppl. Ser. 92, 267–289 (1992).
Witte, M., Rosenbauer, H., Banaskiewicz, M. & Fahr, H. J. Adv. Space Res. 13, 121–126 (1993).
Thomas, G. E. Annu. Rev. Earth Planet. Sci. 6, 173–204 (1978).
Quemerais, E., Bertaux, J.-L., Sandel, B. R. & Lallement, R. Astron. Astrophys. 290, 941–954 (1996).
Vallerga, J. in Proc. 1st ISSI Workshop (eds von Steiger, R., Lallement, R. & Lee, M. A.) Space Sci. Rev. 78, 277–288 (1996).
Frisch, P. C. Space Sci. Rev. 72, 499–592 (1995).
Siscoe, G. L. in Solar System Magnetohydrodynamics: Concepts and Basic Equations in Solar Terrestrial Physics (eds Carovillano, R. L. & Forbes, J. M.) 74–76 (Reidel, Dordrecht, 1983).
Stone, E. C., Cummings, A. C. & Webber, W. R. J. Geophys. Res. 101, 11017–11025 (1996).
Frisch, P. C. in Cosmic Winds and the Heliosphere (eds Jokipii, J. R., Sonett, C. P. & Giampapa, M. S.) (Univ. Arizona Press, Tucson, in the press).
Dupuis, J., Vennes, S., Bowyer, S., Pradhan, A. K. & Thejll, P. Astrophys. J. 455, 574–589 (1995).
Cheng, K.-P. & Bruhweiler, F. C. Astrophys. J. 364, 573–581 (1990).
Burlaga, L. F., Ness, N. F., Belcher, J. W., Lazarus, A. J. & Richardson, J. D. in Proc. 1st ISSI Workshop (eds von Steiger, R., Lallement, R. & Lee, M. A.) Space Sci. Rev. 78, 33–42 (1996).
Geiss, J. & Witte, M. in Proc. 1st ISSI Workshop (eds von Steiger, R., Lallement, R. & Lee, M. A.) Space Sci. Rev. 78, 229–238 (1996).
Anders, E. & Grevesse, N. Geochim. Cosmochim. Acta. 53, 197–214 (1988).
Fite, W. L., Smith, A. C. H. & Stebbings, R. F. Proc. R. Soc. Land. A 268, 527–534 (1962).
Lallement, R., Bertaux, J.-L. & Clarke, J. T. Science 260, 1095–1098 (1993).
Janev, R. K., Langer, W. D., Evans, K. Jr & Post, D. E. Elementary Processes in Hydrogen-Helium Plasmas (Cross Sections and Reaction Rate Coefficients) (Springer, Berlin, 1987).
Gloeckler, G., Schwadron, N. A., Fisk, L. A. & Geiss, J. Geophys. Res. Lett. 22, 2665–2668 (1995).
Fisk, L. A., Schwadron, N. A. & Gloeckler, G. Geophys. Res. Lett. 24, 93–96 (1997).
Rucinski, D. et al. Proc. 1st ISSI Workshop (eds von Steiger, R., Lallement, R. & Lee, M. A.) Space Sci. Rev. 78, 73–84 (1996).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Gloeckler, G., Fisk, L. & Geiss, J. Anomalously small magnetic field in the local interstellar cloud. Nature 386, 374–377 (1997). https://doi.org/10.1038/386374a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/386374a0
This article is cited by
-
Future Exploration of the Outer Heliosphere and Very Local Interstellar Medium by Interstellar Probe
Space Science Reviews (2023)
-
In Situ Observations of Interstellar Pickup Ions from 1 au to the Outer Heliosphere
Space Science Reviews (2022)
-
Filtering of the interstellar dust flow near the heliopause: the importance of secondary electron emission for the grain charging
Earth, Planets and Space (2014)
-
Neutral H Density at the Termination Shock: A Consolidation of Recent Results
Space Science Reviews (2009)
-
Diagnosing the Neutral Interstellar Gas Flow at 1 AU with IBEX-Lo
Space Science Reviews (2009)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.