Discovery of $${{\bf{H}}}_{\mathbf{3}}^{\mathbf{+}}$$ and infrared aurorae at Neptune with JWST
Emissions from the upper-atmospheric molecular ion <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup><mml:mrow><mml:mi>H</mml:mi></mml:mrow> <mml:mrow><mml:mn>3</mml:mn></mml:mrow> <mml:mrow><mml:mo>+</mml:mo></mml:mrow> </mml:msubsup> </mml:math> have been used to study the global-scale interactions of Jupiter, Saturn and Uranus with their surrounding space environments for over 30 years, revealing the processes shaping the aurorae. However, despite repeated attempts, and contrary to models that predict it should be present, this ion has proven elusive at Neptune. Here, using observations from the James Webb Space Telescope, we detect <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup><mml:mrow><mml:mi>H</mml:mi></mml:mrow> <mml:mrow><mml:mn>3</mml:mn></mml:mrow> <mml:mrow><mml:mo>+</mml:mo></mml:mrow> </mml:msubsup> </mml:math> at Neptune, as well as distinct infrared southern auroral emissions. The average upper-atmosphere temperature is a factor of two cooler than those derived 34 years ago by Voyager 2, showing that the energy balance of this region is regulated by physical processes acting on a timescale shorter than both Neptunian seasons (40 yr) and the solar cycle.
Authors
- Oliver King (ORCID: https://orcid.org/0000-0002-6271-0062)
- Naomi Rowe‐Gurney (ORCID: https://orcid.org/0000-0001-8692-5538)
- Heidi B. Hammel (ORCID: https://orcid.org/0000-0001-8751-3463)
- James O’Donoghue (ORCID: https://orcid.org/0000-0002-4218-1191)
- Emma Thomas (ORCID: https://orcid.org/0000-0002-5773-6110)
- Luke Moore (ORCID: https://orcid.org/0000-0003-4481-9862)
- Stefanie N. Milam (ORCID: https://orcid.org/0000-0001-7694-4129)
- Ruoyan Wang (ORCID: https://orcid.org/0000-0002-4563-8919)
- Leigh N. Fletcher (ORCID: https://orcid.org/0000-0001-5834-9588)
- Katie Knowles (ORCID: https://orcid.org/0000-0001-5055-8115)
- Tom Stallard (ORCID: https://orcid.org/0000-0003-3990-670X)
- Jake Harkett (ORCID: https://orcid.org/0009-0007-1223-8752)
- Michael T. Roman (ORCID: https://orcid.org/0000-0001-8206-2165)
- Henrik Melin (ORCID: https://orcid.org/0000-0001-5971-2633)
- Paola Tiranti (ORCID: https://orcid.org/0000-0001-7339-9495)
Institutions
- Boston University (US)
- Goddard Space Flight Center (US)
- Association of Universities for Research in Astronomy (US)
- University of Leicester (GB)
- Universities Research Association (US)
- Northumbria University (GB)
- University of Massachusetts Boston (US)
- Institute of Space and Astronautical Science (JP)
- University of Reading (GB)
Publication Details
- Journal
- Nature Astronomy
- Published
- 2025-03-26
- DOI
- https://doi.org/10.1038/s41550-025-02507-9
- Citations
- 7
- Primary Topic
- Astro and Planetary Science
- Type
- article
- Field-Weighted Citation Impact
- 8.08