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An Orbital Window into the Ancient Sun’s Mass

Spalding, Christopher and Fischer, Woodward W. and Laughlin, Gregory (2018) An Orbital Window into the Ancient Sun’s Mass. Astrophysical Journal Letters, 869 (1). Art. No. L19. ISSN 2041-8213.

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Models of the Sun's long-term evolution suggest that its luminosity was substantially reduced 2–4 billion years ago, which is inconsistent with substantial evidence for warm and wet conditions in the geological records of both ancient Earth and Mars. Typical solutions to this so-called "faint young Sun paradox" consider changes in the atmospheric composition of Earth and Mars, and, while attractive, geological verification of these ideas is generally lacking—particularly for Mars. One possible underexplored solution to the faint young Sun paradox is that the Sun has simply lost a few percent of its mass during its lifetime. If correct, this would slow, or potentially even offset, the increase in luminosity expected from a constant-mass model. However, this hypothesis is challenging to test. Here, we propose a novel observational proxy of the Sun's ancient mass that may be readily measured from accumulation patterns in sedimentary rocks on Earth and Mars. We show that the orbital parameters of the Solar System planets undergo quasi-cyclic oscillations at a frequency, given by secular mode g_2 − g_5, that scales approximately linearly with the Sun's mass. Thus by examining the cadence of sediment accumulation in ancient basins, it is possible distinguish between the cases of a constant-mass Sun and a more massive ancient Sun to a precision of greater than about 1 percent. This approach provides an avenue toward verification, or of falsification, of the massive early Sun hypothesis.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Spalding, Christopher0000-0001-9052-3400
Fischer, Woodward W.0000-0002-8836-3054
Laughlin, Gregory0000-0002-3253-2621
Additional Information:© 2018. The American Astronomical Society. Received 2018 October 1; revised 2018 November 16; accepted 2018 November 17; published 2018 December 11. C.S thanks Noah Planavksy and Konstantin Batygin for useful discussions. We are grateful to the referee for a thorough report that greatly improved the manuscript. This research is based in part upon work supported by NSF grant AST 1517936, NESSF Graduate Fellowship in Earth and Planetary Sciences and the 51 Pegasi b Heising-Simons Foundation grant (C.S).
Funding AgencyGrant Number
National Security Science and Engineering Faculty FellowshipUNSPECIFIED
Heising-Simons FoundationUNSPECIFIED
Subject Keywords:Earth; planets and satellites: terrestrial planets; solar wind
Issue or Number:1
Record Number:CaltechAUTHORS:20181211-101728833
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Official Citation:Christopher Spalding et al 2018 ApJL 869 L19
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91681
Deposited By: George Porter
Deposited On:11 Dec 2018 22:22
Last Modified:03 Oct 2019 20:37

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