Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Magnetic field and particle measurements made by Voyager 2 at and near the heliopause

Abstract

The heliopause is a boundary that separates the heliosheath (which contains magnetic fields and plasmas that originate in the Sun) from the interstellar medium (which contains magnetic fields and particles of stellar/interstellar origin). Observations of the heliopause were first made by the particles and fields instruments on the Voyager 1 spacecraft, moving radially in the northern hemisphere, which crossed the heliopause on 25 August 2012 at a distance of 121.6 au. We show using observations of the magnetic field and energetic particles that Voyager 2 crossed the heliopause in the southern hemisphere on 5 November 2018 at a distance of ≈119.0 au. Voyager 2 observed a much thinner and simpler heliopause than Voyager 1 as well as stronger interstellar magnetic fields, and it discovered a ‘magnetic barrier’ in the heliosheath adjacent to the heliopause that strongly influences the entry of cosmic rays into the heliosphere. The magnetic field direction observed by Voyager 2 changed smoothly from the time of arrival at the magnetic barrier, through it, and onwards into the interstellar medium, with a small (a few degrees) or no change across the heliopause. These observations, together with the Voyager 1 observations and existing models, show that the magnetic barrier, the heliopause and the neighbouring very local interstellar medium form a complex interconnected dynamical system.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: The heliopause crossing observed by Voyager 2 in the measurements of the magnetic field and the >0.5 MeV nucleon–1 energetic particles.
Fig. 2: The heliopause crossing of Voyager 2 and the neighbouring heliosheath and VLISM in terms of the temporal variation of B, λ and δ.
Fig. 3: The RTN components of B and the magnitude of B as a function of time just before and after the heliopause crossing of Voyager 2.
Fig. 4: The magnetic field and plasma in the outer heliosheath, the magnetic barrier and the VLISM, as measured by Voyager 2.
Fig. 5: Magnetic field strength B in the plane containing the trajectories of Voyager 1 and Voyager 2.
Fig. 6: The relationship between the magnetic barrier and cosmic rays, and the variation of the magnetic field direction across the heliopause.

Data availability

The 48 s averages of the magnetic field data are posted on NASA’s Space Science Data Facility (SPDF) CDAWeb site: https://cdaweb.gsfc.nasa.gov/index.html/. The hour averages of the magnetic field data are posted on NASA’s Space Science Data Facility (SPDF) COHOWeb site https://omniweb.sci.gsfc.nasa.gov/coho/.

References

  1. 1.

    Davis, L. Interplanetary magnetic fields and cosmic rays. Phys. Rev. 100, 1440–1444 (1955).

    ADS  Article  Google Scholar 

  2. 2.

    Parker, E. N. The stellar-wind regions. Astrophys. J. Lett. 134, 20–27 (1961).

    ADS  Article  Google Scholar 

  3. 3.

    Holzer, T. E. Interaction of the solar wind with the neutral component of the interstellar gas. J. Geophys. Res. 77, 5407–5431 (1972).

    ADS  Article  Google Scholar 

  4. 4.

    Baranov, V. B., Krasnobarev, K. V. & Ruderman, M. S. On the model of the solar wind-interstellar medium interaction with two shock waves. Astrophys. Space Sci. 41, 481–490 (1976).

    ADS  Article  Google Scholar 

  5. 5.

    Holzer, T. Interaction between the solar wind and the interstellar medium. Annu. Rev. Astron. Astrophys. 27, 199–234 (1989).

    ADS  Article  Google Scholar 

  6. 6.

    Zank, G. P. Faltering steps into the Galaxy: the boundary regions of the heliosphere. Annu. Rev. Astron. Astrophys. 53, 449–500 (2015).

    ADS  Article  Google Scholar 

  7. 7.

    Burlaga, L., Ness, N. F. & Stone, E. C. Magnetic field observations as Voyager 1 entered the heliosheath depletion region. Science 341, 148–150 (2013).

    ADS  Article  Google Scholar 

  8. 8.

    Gurnett, D. A., Kurth, W. S., Burlaga, L. F. & Ness, N. F. In situ observations of interstellar plasma with Voyager 1. Science 341, 1489–1492 (2013).

    ADS  Article  Google Scholar 

  9. 9.

    Krimigis, S. M. et al. Search for the exit: Voyager 1 at heliosphere’s border with the galaxy. Science 341, 144–147 (2013).

    ADS  Article  Google Scholar 

  10. 10.

    Stone, E. C. et al. Voyager 1 observes low-energy galactic cosmic rays in a region depleted of heliospheric ions. Science 341, 150–153 (2013).

    ADS  Article  Google Scholar 

  11. 11.

    Grygorczuk, J. A., Czechowski, A. & Grzedzielski, S. Why are the magnetic field directions measured by Voyager 1 on both sides of the heliopause so similar? Astrophys. J. Lett. 789, L43–L46 (2014).

    ADS  Article  Google Scholar 

  12. 12.

    Schwadron, N. A. & McComas, D. J. Effects of solar activity on the local interstellar magnetic field observed by Voyager 1 and IBEX. Astrophys. J. 849, 135–145 (2017).

    ADS  Article  Google Scholar 

  13. 13.

    Pogorelov, N. V. et al. Three-dimensional features of the outer heliosphere due to coupling between the interstellar and heliospheric magnetic field. V. The bow wave, heliospheric boundary layer, instabilities, and magnetic reconnection. Astrophys. J. 845, 9 (2017).

    ADS  Article  Google Scholar 

  14. 14.

    Burlaga, L. F. & Ness, N. F. Voyager 1 observations of the interstellar magnetic field and the transition from the heliosheath. Astrophys. J. 784, 146–160 (2014).

    ADS  Article  Google Scholar 

  15. 15.

    Burlaga, L. F. & Ness, N. F. Interstellar magnetic fields observed by Voyager 1 beyond the heliopause. Astrophys. J. Lett. 795, L19–L23 (2014).

    ADS  Article  Google Scholar 

  16. 16.

    Borovikov, S. N. & Pogorelov, N. V. Voyager 1 near the heliopause. Astrophys. J. Lett. 783, L16–L21 (2014).

    ADS  Article  Google Scholar 

  17. 17.

    Pogorelov, N. V. et al. Unsteady processes in the vicinity of the heliopause: are we in the LISM yet? AIP Conf. Proc. 1539, 352–355 (2013).

    ADS  Article  Google Scholar 

  18. 18.

    Pogorelov, N. V. et al. Radial velocity along the Voyager 1 trajectory: the effect of solar cycle. Astrophys. J. Lett. 750, L4–L10 (2012).

    ADS  Article  Google Scholar 

  19. 19.

    Whang, Y. C. Interstellar magnetic field surrounding the heliopause. Astrophys. J. 710, 936–940 (2010).

    ADS  Article  Google Scholar 

  20. 20.

    Opher, M. et al. A strong, highly-tilted interstellar magnetic field near the solar magnetic field. Nature 462, 1036–1038 (2009).

    ADS  Article  Google Scholar 

  21. 21.

    Opher, M., Drake, J. F., Swisdak, M., Zieger, B. & Toth, G. The twist of the draped interstellar magnetic field ahead of the heliopause: a magnetic reconnection driven rotational discontinuity. Astrophys. J. 839, L12–L18 (2017).

    ADS  Article  Google Scholar 

  22. 22.

    Behannon, K. et al. Magnetic field experiment for Voyagers 1 and 2. Space Sci. Rev. 21, 235–257 (1977).

    ADS  Article  Google Scholar 

  23. 23.

    Berdichevsky, D. B. Voyager Mission, Detailed Processing of Weak Magnetic Fields; Constraints to the Uncertainties of the Calibrated Magnetic Field Signal in the Voyager Missions https://go.nature.com/2owpT0w (2009).

  24. 24.

    Burlaga, L. F. Interplanetary Magnetohydrodynamics (Oxford Univ. Press, 1995).

  25. 25.

    Nerney, S., Suess, S. T. & Schmahl, E. J. Flow downstream of the heliospheric terminal shock—magnetic field kinematics. Astron. Astrophys. 250, 556–564 (1991).

    ADS  Google Scholar 

  26. 26.

    Nerney, S., Suess, S. T. & Schmahl, E. J. Flow downstream of the heliospheric terminal shock: the magnetic field in the heliopause. J. Geophys. Res. 98, 15169–15176 (1993).

    ADS  Article  Google Scholar 

  27. 27.

    Washimi, H. & Tanaka, T. 3-D magnetic field and current system in the heliosphere. Space Sci. Rev. 78, 85–94 (1996).

    ADS  Article  Google Scholar 

  28. 28.

    Washimi, H., Zank, G. P., Hu, Q., Tanaka, T. & Munakata, K. MHD modeling of the outer heliospheric structures around the heliopause. Astrophys. J. 809, 16–28 (2015).

    ADS  Article  Google Scholar 

  29. 29.

    Washimi, H., Hu, Q., Tanaka, T., Munakata, K. & Shinagawa, H. Realistic and time-varying outer heliospheric modelling. Mon. Not. R. Astron. Soc. 416, 1475–1485 (2011).

    ADS  Article  Google Scholar 

  30. 30.

    Drake, J. F., Swisdak, M., Opher, M. & Richardson, J. D. The formation of magnetic depletions and flux annihilation due to reconnection in the heliosheath. Astrophys. J. 837, 159 (2017).

    ADS  Article  Google Scholar 

  31. 31.

    Burlaga, L. F., Ness, N. F., Gurnett, D. A. & Kurth, W. S. Evidence for a shock in interstellar plasma: Voyager 1. Astrophys. J. Lett. 778, L3 (2013).

    ADS  Article  Google Scholar 

  32. 32.

    Burlaga, L. F. et al. A magnetic pressure front upstream of the heliopause, and the heliosheath magnetic fields and plasma, observed during 2017. Astrophys. J. Lett. 877, 31 (2019).

    ADS  Article  Google Scholar 

  33. 33.

    Berdichevsky, D. B. Voyager Mission, Detailed Processing of Weak Magnetic Fields; II- Update on the Cleaning of Voyager Magnetic Field Density B with MAGCALs https://go.nature.com/2mTk8t8 (2015).

  34. 34.

    Stone, E. C., Cummings, A. C., Heikkila, B. C. & Lal, N. Cosmic ray measurements from Voyager 2 as it crossed into interstellar space. Nat. Astron. https://doi.org/10.1038/s41550-019-0928-3 (2019).

Download references

Acknowledgements

L.F.B., N.F.N., D.B.B., J.P., L.K.J. and A.S. were supported by the NASA Voyager Project to the NASA/GSFC Magnetometer Team under internal NASA funding. L.K.J. is grateful for support from The International Space Science Institute in Bern in the framework of the team ‘The Physics of the Very Local Interstellar Medium’. L.F.B. thanks N. Pogorelov and H. Washimi for helpful discussions, and N. Pogorelov for preparing Fig. 5. J.D.R. was supported by NASA under grant number 959203 from the Jet Propulsion Laboratory to the Massachusetts Institute.

Author information

Affiliations

Authors

Contributions

L.F.B. wrote the initial draft of the manuscript, incorporated contributions from the other authors, compiled and submitted the final paper, prepared the final edited datasets, and submitted the data to the NASA archives. N.F.N. is the principal investigator of the magnetic field investigation. D.B.B. calibrated the magnetic field data. J.P. and L.K.J. assisted in data calibrations and made contributions to the paper. A.S. managed the data processing and the budget. J.D.R. provided the plasma data and contributed to their interpretation. E.C.S. provided the cosmic ray data and >0.5 MeV data and contributed to the interpretation of the data.

Corresponding author

Correspondence to L. F. Burlaga.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Burlaga, L.F., Ness, N.F., Berdichevsky, D.B. et al. Magnetic field and particle measurements made by Voyager 2 at and near the heliopause. Nat Astron 3, 1007–1012 (2019). https://doi.org/10.1038/s41550-019-0920-y

Download citation

Further reading

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing