| The Hertzsprung-Russell (HR) diagram is one of the most important diagrams in astronomy.
In a HR diagram, the luminosity of stars and/or stellar remnants (white dwarf stars, WD’s),
relative to the luminosity of the sun, is plotted versus their surface temperatures
(Teff). The Earth shows a striking similarity in size (radius ≈ 6.371 km) and Teff of
its outer core surface (Teff ≈ 3800 K at the core-mantle-boundary) with old
WD’s (radius ≈ 6.300 km) like WD0346+246 (Teff ≈ 3820 K after ≈ 12.7 Ga
[1]), which plot in the HR diagram close to the low-mass extension of the stellar
population or main sequence. In the light of nuclear planetology [2], Earth-like planets
are regarded as old, down-cooled and differentiated black dwarfs (Fe-C BLD’s)
after massive decompression, the most important nuclear reactions involved being
56Fe(γ,α)52Cr (etc.), possibly responsible for extreme terrestrial glaciations events
(“snowball” Earth), together with (γ,n), (γ,p) and fusion reactions like 12C(α,γ)16O. The
latter reaction might have caused oxidation of the planet from inside out. Nuclear
planetology is a new research field, tightly constrained by a coupled 187Re-232Th-238U
systematics [3-5]. By means of nuclear/quantum physics and taking the theory of
relativity into account, it aims at understanding the thermal and chemical evolution
of Fe-C BLD’s after gravitational contraction (e.g. Mercury) or Fermi-pressure
controlled collapse (e.g. Earth) events after massive decompression, leading possibly to
an r-process event, towards the end of their cooling period [2]. So far and based
upon 187Re-232Th-238U nuclear geochronometry, the Fe-C BLD hypothesis can
successfully explain the global terrestrial MORB 232Th/238U signature [5]. Thus, it
may help to elucidate the DM (depleted mantle), EMI (enriched mantle 1), EMII
(enriched mantle 2) or HIMU (high U/Pb) reservoirs [6], and the 187Os/188Os isotopic
dichotomy in Archean magmatic rocks and sediments [7]. Here I present a conceptual
model constraining the evolution of a rocky planet like Earth or Mercury from a
stellar precursor of the oldest population to a Fe-C BLD, shifting through different
spectral classes in a HR diagram after massive decompression and tremendous energy
losses. In the light of WD/BLD cosmochronology [1], solar system bodies like
Earth, Mercury and Moon are regarded as captured interlopers from the Galactic
bulge, Earth and Moon possibly representing remnants of an old binary system.
Such a preliminary scenario is supported by similar ages obtained from WD’s for
the Galactic halo [1] and, independently, by means of 187Re-232Th-238U nuclear
geochronometry [3, 4], together with recent observations extremely metal-poor stars
from the cosmic dawn in the bulge of the Milky Way [8]. This might be further
elucidated in the near future by Th/U cosmochronometry based upon a nuclear
production ratio Th/U = 0.96 [9] and additionally by means of a newly developed
nucleogeochronometric age dating method for stellar spectroscopy [9-11]. The
model shall stimulate geochemical data interpretation from a different perspective, to
constrain the evolution and differentiation of planetary or lunar crusts and mantles in
general.
[1] Fontaine et al. (2001), Public. Astron. Soc. of the Pacific 113, 409-435. [2] Roller
(2015), Abstract T34B-0407, AGU Spring Meeting 2015. [3] Roller (2016), Goldschmidt
Conf. Abstr. 26, 2642. [4] Roller (2015), Goldschmidt Conf. Abstr. 25, 2672. [5] Roller
(2015), Geophys. Res. Abstr. 18, EGU2016-33. [6] Arevalo et al. (2010), Chem. Geol. 271,
70-85. [7] Roller (2015), Geophys. Res. Abstr. 17, EGU2015-2399. [8] Howes et al. (2015),
Nature 527, 484-487. [9] Roller (2016), JPS Conf. Proc., Nuclei in the Cosmos (NIC XIV),
Niigata, Japan, subm. (NICXIV-001); NICXIV Abstr. #1570244284. [10] Roller (2016), JPS
Conf. Proc., Nuclei in the Cosmos (NIC XIV), Niigata, Japan, subm. (NICXIV-002); NICXIV
Abstr. #1570244285. [11] Roller (2016), JPS Conf. Proc., Nuclei in the Cosmos
(NIC XIV), Niigata, Japan, subm. (NICXIV-003); NICXIV Abstr. #1570244281. |