Exploring the hypothesis of an inverted Z gradient inside Jupiter

Astronomy and Astrophysics, vol. 680, pp. L2

Abstract

Context. Reconciling models of Jupiter’s interior with measurements of the atmospheric composition still poses a significant challenge. Interior models favour a subsolar or solar abundance of heavy elements, Z, whereas atmospheric measurements suggest a supersolar abundance. One potential solution may be to account for the presence of an inverted Z gradient, namely, an inward decrease of Z, which implies a higher heavy-element abundance in the atmosphere than in the outer envelope. Aims. We investigate two scenarios in which the inverted Z gradient is either located at levels where helium rain occurs (∼Mbar) or at higher levels (∼kbar) where a radiative region could exist. Here, we aim to assess the plausibility of these scenarios. Methods. We calculated interior and evolution models of Jupiter with such an inverted Z gradient and we set constraints on its stability and formation. Results. We find that an inverted Z gradient at the location of helium rain is not feasible, as it would require a late accretion and would involve too much material. We find interior models with an inverted Z gradient at upper levels due to a radiative zone preventing downward mixing, could satisfy the current gravitational field of the planet. However, our evolution models suggest that this second scenario cannot be validated. Conclusions. We find that an inverted Z gradient in Jupiter could indeed be stable, however, its presence either at the Mbar or kbar levels is rather unlikely.

Authors 9

1. Saburo Howard

   Centre National de la Recherche Scientifique · Université Côte d'Azur · Lagrange Laboratory · Observatoire de la Côte d’Azur

   Affiliation as printed

   Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France

   LAGRANGE - Joseph Louis LAGRANGE (Boulevard de l'Observatoire B.P. 4229 06304 Nice Cedex 04 - France - France)

   OCA - Observatoire de la Côte d'Azur (B.P. 4229 06304 Nice Cedex 4 - France)

2. Tristan Guillot

   Centre National de la Recherche Scientifique · Université Côte d'Azur · Lagrange Laboratory · Observatoire de la Côte d’Azur

   Affiliation as printed

   Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France

   LAGRANGE - Joseph Louis LAGRANGE (Boulevard de l'Observatoire B.P. 4229 06304 Nice Cedex 04 - France - France)

3. Stephen Markham

   Centre National de la Recherche Scientifique · Université Côte d'Azur · Lagrange Laboratory · Observatoire de la Côte d’Azur

   Affiliation as printed

   Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France

   LAGRANGE - Joseph Louis LAGRANGE (Boulevard de l'Observatoire B.P. 4229 06304 Nice Cedex 04 - France - France)

   OCA - Observatoire de la Côte d'Azur (B.P. 4229 06304 Nice Cedex 4 - France)

4. Ravit Helled

   University of California, Santa Cruz · University of Zurich · Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) · Institut de Systématique, Évolution, Biodiversité

   Affiliation as printed

   Institute for Computational Science, Center for Theoretical Astrophysics & Cosmology, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland

   DLR Institute of Planetary Research (Berlin - Germany)

   Department of Astronomy and Astrophysics [UCSC Santa Cruz] (477 Clark Kerr Hall, Santa Cruz, CA, 95064 - United States)

   ISYEB - Institut de Systématique, Evolution, Biodiversité (57 rue Cuvier - CP 50 - 75005 Paris - France)

   Institute for Computational Science [Zürich] (Winterthurerstrasse 190, 8057 Zürich - Switzerland)

5. Simon Müller

   University of California, Santa Cruz · University of Zurich · Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) · Institut de Systématique, Évolution, Biodiversité

   Affiliation as printed

   Institute for Computational Science, Center for Theoretical Astrophysics & Cosmology, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland

   DLR Institute of Planetary Research (Berlin - Germany)

   Department of Astronomy and Astrophysics [UCSC Santa Cruz] (477 Clark Kerr Hall, Santa Cruz, CA, 95064 - United States)

   ISYEB - Institut de Systématique, Evolution, Biodiversité (57 rue Cuvier - CP 50 - 75005 Paris - France)

   Institute for Computational Science [Zürich] (Winterthurerstrasse 190, 8057 Zürich - Switzerland)

6. D. J. Stevenson

   California Institute of Technology

   Affiliation as printed

   Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA

   School of GeoSciences (United Kingdom)

7. Jonathan I. Lunine

   Cornell University

   Affiliation as printed

   Carl Sagan Institute, Cornell University, 122 Sciences Drive, Ithaca, NY 14853, USA

   Department of Astronomy, Cornell University, 122 Sciences Drive, Ithaca, NY 14853, USA

   Cornell University [New York] (Ithaca, New York 14853 - United States)

8. Yamila Miguel Aachen Leiden Observatory SRON Netherlands Institute for Space Research SRON - SRON Netherlands Institute for Space Research (SRON Groningen

   Leiden University · Leiden Observatory · Space Research Organisation Netherlands

   Affiliation as printed

   Leiden Observatory, University of Leiden, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands

   SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands

   Leiden Observatory [Leiden] (P.O. Box 9513, NL-2300 RA Leiden - Netherlands)

   SRON - SRON Netherlands Institute for Space Research (SRON Groningen, Landleven 12, 9747 AD Groningen - SRON Utrecht, Sorbonnelaan 2, 3584 CA Utrecht - Netherlands)

9. Nadine Nettelmann

   University of California, Santa Cruz · University of Zurich · Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) · Institut de Systématique, Évolution, Biodiversité

   Affiliation as printed

   Institute for Computational Science, Center for Theoretical Astrophysics & Cosmology, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland

   DLR Institute of Planetary Research (Berlin - Germany)

   Department of Astronomy and Astrophysics [UCSC Santa Cruz] (477 Clark Kerr Hall, Santa Cruz, CA, 95064 - United States)

   ISYEB - Institut de Systématique, Evolution, Biodiversité (57 rue Cuvier - CP 50 - 75005 Paris - France)

   Institute for Computational Science [Zürich] (Winterthurerstrasse 190, 8057 Zürich - Switzerland)