scholarly journals Potassium isotope anomalies in meteorites inherited from the protosolar molecular cloud

2020 ◽  
Vol 6 (41) ◽  
pp. eabd0511 ◽  
Author(s):  
Y. Ku ◽  
S. B. Jacobsen
Keyword(s):  
Solar System ◽  
Isotopic Composition ◽  
Thermal Processing ◽  
Molecular Cloud ◽  
Protoplanetary Disk ◽  
The Sun ◽  
Volatile Elements ◽  
Heterogeneous Distribution ◽  
Solar System Bodies ◽  
K Depletion

Potassium (K) and other moderately volatile elements are depleted in many solar system bodies relative to CI chondrites, which closely match the composition of the Sun. These depletions and associated isotopic fractionations were initially believed to result from thermal processing in the protoplanetary disk, but so far, no correlation between the K depletion and its isotopic composition has been found. Our new high-precision K isotope data correlate with other neutron-rich nuclides (e.g., 64Ni and 54Cr) and suggest that the observed 41K variations have a nucleosynthetic origin. We propose that K isotope anomalies are inherited from an isotopically heterogeneous protosolar molecular cloud, and were preserved in bulk primitive meteorites. Thus, the heterogeneous distribution of both refractory and moderately volatile elements in chondritic meteorites points to a limited radial mixing in the protoplanetary disk.

scholarly journals The Grand Tack model: a critical review

2014 ◽  
Vol 9 (S310) ◽  
pp. 194-203 ◽  
Author(s):  
Sean N. Raymond ◽  
Alessandro Morbidelli
Keyword(s):  
Solar System ◽  
Building Blocks ◽  
Protoplanetary Disk ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Terrestrial Planets ◽  
Saturn’S Satellites ◽  
Internal Inconsistency ◽  
Solar System Bodies ◽  
Gas Accretion

AbstractThe “Grand Tack” model proposes that the inner Solar System was sculpted by the giant planets' orbital migration in the gaseous protoplanetary disk. Jupiter first migrated inward then Jupiter and Saturn migrated back outward together. If Jupiter's turnaround or “tack” point was at ~ 1.5 AU the inner disk of terrestrial building blocks would have been truncated at ~ 1 AU, naturally producing the terrestrial planets' masses and spacing. During the gas giants' migration the asteroid belt is severely depleted but repopulated by distinct planetesimal reservoirs that can be associated with the present-day S and C types. The giant planets' orbits are consistent with the later evolution of the outer Solar System.Here we confront common criticisms of the Grand Tack model. We show that some uncertainties remain regarding the Tack mechanism itself; the most critical unknown is the timing and rate of gas accretion onto Saturn and Jupiter. Current isotopic and compositional measurements of Solar System bodies – including the D/H ratios of Saturn's satellites – do not refute the model. We discuss how alternate models for the formation of the terrestrial planets each suffer from an internal inconsistency and/or place a strong and very specific requirement on the properties of the protoplanetary disk.We conclude that the Grand Tack model remains viable and consistent with our current understanding of planet formation. Nonetheless, we encourage additional tests of the Grand Tack as well as the construction of alternate models.

scholarly journals Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

2016 ◽  
Vol 113 (8) ◽  
pp. 2011-2016 ◽  
Author(s):  
Elishevah M. M. E. Van Kooten ◽  
Daniel Wielandt ◽  
Martin Schiller ◽  
Kazuhide Nagashima ◽  
Aurélien Thomen ◽  
...  
Keyword(s):  
Solar System ◽  
Thermal Processing ◽  
Molecular Cloud ◽  
Decay Product ◽  
Isotopic Signature ◽  
Carbonaceous Chondrites ◽  
Outer Solar System ◽  
Precursor Material ◽  
System Composition ◽  
Cloud Material

The short-lived 26Al radionuclide is thought to have been admixed into the initially 26Al-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent 54Cr and 26Mg*, the decay product of 26Al. This correlation is interpreted as reflecting progressive thermal processing of in-falling 26Al-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived 26Al has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a 26Mg*-depleted and 54Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived 26Al. The 26Mg* and 54Cr compositions of bulk metal-rich chondrites require significant amounts (25–50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants.

scholarly journals Oxygen isotopic heterogeneity in the early Solar System inherited from the protosolar molecular cloud

2020 ◽  
Vol 6 (42) ◽  
pp. eaay2724
Author(s):  
Alexander N. Krot ◽  
Kazuhide Nagashima ◽  
James R. Lyons ◽  
Jeong-Eun Lee ◽  
Martin Bizzarro
Keyword(s):  
Solar System ◽  
Molecular Cloud ◽  
Limited Range ◽  
Terrestrial Planets ◽  
Carbonaceous Chondrites ◽  
The Sun ◽  
Early Solar System ◽  
Isotopic Heterogeneity ◽  
Oxygen Isotopic ◽  
O 24

The Sun is 16O-enriched (Δ17O = −28.4 ± 3.6‰) relative to the terrestrial planets, asteroids, and chondrules (−7‰ < Δ17O < 3‰). Ca,Al-rich inclusions (CAIs), the oldest Solar System solids, approach the Sun’s Δ17O. Ultraviolet CO self-shielding resulting in formation of 16O-rich CO and 17,18O-enriched water is the currently favored mechanism invoked to explain the observed range of Δ17O. However, the location of CO self-shielding (molecular cloud or protoplanetary disk) remains unknown. Here we show that CAIs with predominantly low (26Al/27Al)0, <5 × 10−6, exhibit a large inter-CAI range of Δ17O, from −40‰ to −5‰. In contrast, CAIs with the canonical (26Al/27Al)0 of ~5 × 10−5 from unmetamorphosed carbonaceous chondrites have a limited range of Δ17O, −24 ± 2‰. Because CAIs with low (26Al/27Al)0 are thought to have predated the canonical CAIs and formed within first 10,000–20,000 years of the Solar System evolution, these observations suggest oxygen isotopic heterogeneity in the early solar system was inherited from the protosolar molecular cloud.

3. Beautiful theories, ugly facts

2021 ◽  
pp. 31-46
Author(s):  
Raymond T. Pierrehumbert
Keyword(s):  
Angular Momentum ◽  
Solar System ◽  
Planetary Systems ◽  
Protoplanetary Disk ◽  
Newtonian Gravity ◽  
The Sun ◽  
French Mathematician ◽  
Modern Form

‘Beautiful theories, ugly facts’ evaluates the theories on planetary systems, particularly the Solar System. In 1734, the Swedish polymath Emmanuel Swedenborg proposed that the Sun and all the planets condensed out of the same ball of gas, in what is probably the earliest statement of the nebular hypothesis. The nebular hypothesis entered something close to its modern form in the hands of the French mathematician Pierre-Simon Laplace, who in 1796 made the clear connection to Newtonian gravity. The angular momentum problem and the structure of a protoplanetary disk, the formation of rocky cores, and the gravitational accretion of gas in the disk also come under this topic.

scholarly journals Cometary Chemistry and the Origin of Icy Solar System Bodies: The View After Rosetta

2019 ◽  
Vol 57 (1) ◽  
pp. 113-155 ◽  
Author(s):  
Kathrin Altwegg ◽  
Hans Balsiger ◽  
Stephen A. Fuselier
Keyword(s):  
Solar System ◽  
Protoplanetary Disk ◽  
Isotopic Ratios ◽  
Parent Species ◽  
Rosetta Mission ◽  
Solar System Bodies ◽  
Diverse Origin ◽  
Life On Earth ◽  
Collapsing Cloud

In situ research of cometary chemistry began when measurements from the Giotto mission at Comet 1P/Halley revealed the presence of complex organics in the coma. New telescopes and space missions have provided detailed remote and in situ measurements of the composition of cometary volatiles. Recently, the Rosetta mission to Comet 67P/Churyumov–Gerasimenko (67P) more than doubled the number of parent species and the number of isotopic ratios known for comets. Forty of the 71 parent species have also been detected in pre- and protostellar clouds. Most isotopic ratios are nonsolar. This diverse origin is in contrast to that of the Sun, which received its material from the bulk of the collapsing cloud. The xenon isotopic ratios measured in 67P can explain the long-standing question about the origin of terrestrial atmospheric xenon. These findings strengthen the notion that comets are indeed an important link between the ISM and today's solar system including life on Earth. ▪ Nonsolar isotopic ratios for species such as Xe, N, S, and Si point to a nonhomogenized protoplanetary disk from which comets received their material. ▪ The similarity of the organic inventories of comets and presolar and protostellar material makes it plausible that this material was accreted almost unaltered by comets from the presolar stage. ▪ Large variations in the deuterium-to-hydrogen ratio in water for comets indicate a large range in the protoplanetary disk from which comets formed. ▪ The amount of organics delivered by comets to Earth may be highly significant.

scholarly journals The solar gravitational redshift from HARPS-LFC Moon spectra

2020 ◽  
Vol 643 ◽  
pp. A146
Author(s):  
J. I. González Hernández ◽  
R. Rebolo ◽  
L. Pasquini ◽  
G. Lo Curto ◽  
P. Molaro ◽  
...  
Keyword(s):  
Solar System ◽  
Spectral Range ◽  
Frequency Comb ◽  
Line Shift ◽  
Spectral Lines ◽  
Gravitational Redshift ◽  
Solar Photosphere ◽  
The Sun ◽  
The Moon ◽  
Solar System Bodies

Context. The general theory of relativity predicts the redshift of spectral lines in the solar photosphere as a consequence of the gravitational potential of the Sun. This effect can be measured from a solar disk-integrated flux spectrum of the Sun’s reflected light on Solar System bodies. Aims. The laser frequency comb (LFC) calibration system attached to the HARPS spectrograph offers the possibility of performing an accurate measurement of the solar gravitational redshift (GRS) by observing the Moon or other Solar System bodies. Here, we analyse the line shift observed in Fe absorption lines from five high-quality HARPS-LFC spectra of the Moon. Methods. We selected an initial sample of 326 photospheric Fe lines in the spectral range between 476–585 nm and measured their line positions and equivalent widths (EWs). Accurate line shifts were derived from the wavelength position of the core of the lines compared with the laboratory wavelengths of Fe lines. We also used a CO5BOLD 3D hydrodynamical model atmosphere of the Sun to compute 3D synthetic line profiles of a subsample of about 200 spectral Fe lines centred at their laboratory wavelengths. We fit the observed relatively weak spectral Fe lines (with EW< 180 mÅ) with the 3D synthetic profiles. Results. Convective motions in the solar photosphere do not affect the line cores of Fe lines stronger than about ∼150 mÅ. In our sample, only 15 Fe I lines have EWs in the range 150< EW(mÅ) < 550, providing a measurement of the solar GRS at 639 ± 14 m s−1, which is consistent with the expected theoretical value on Earth of ∼633.1 m s−1. A final sample of about 97 weak Fe lines with EW < 180 mÅ allows us to derive a mean global line shift of 638 ± 6 m s−1, which is in agreement with the theoretical solar GRS. Conclusions. These are the most accurate measurements of the solar GRS obtained thus far. Ultrastable spectrographs calibrated with the LFC over a larger spectral range, such as HARPS or ESPRESSO, together with a further improvement on the laboratory wavelengths, could provide a more robust measurement of the solar GRS and further testing of 3D hydrodynamical models.

scholarly journals Comments

1990 ◽  
Vol 123 ◽  
pp. 417-419
Author(s):  
Fred Hoyle
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Molecular Cloud ◽  
The Sun ◽  
Ultimate Explanation ◽  
Word Origin ◽  
Entire Universe ◽  
A Chain ◽  
The Magnetic Field

The word 'origin' is one of the most widely used in science. Yet it seems to me to be always used either improperly or ineffectively. Ineffective uses have a derivative quality about them. As an example, suppose we ask: What was the 'origin' of the magnetic field of the Sun? The best answer I suppose is that the magnetic field of the Sun was formed by the compression of a magnetic field that was present already in the gases of the molecular cloud in which the Sun and Solar System were formed some 4.5 X 109 years ago. But what then was the 'origin' of the field in the molecular cloud? It was present already in the gases from which our galaxy was formed, one might suggest. A further displacement then takes us to the manner of 'origin' of t he entire universe, so that no ultimate explanation has really been given. The problem has only been displaced along a chain until it passes into a mental fog through which some claim to see clearly but through which others, including myself, do not see at all.

scholarly journals Earth’s water may have been inherited from material similar to enstatite chondrite meteorites

Science ◽  
2020 ◽  
Vol 369 (6507) ◽  
pp. 1110-1113 ◽  
Author(s):  
Laurette Piani ◽  
Yves Marrocchi ◽  
Thomas Rigaudier ◽  
Lionel G. Vacher ◽  
Dorian Thomassin ◽  
...  
Keyword(s):  
Solar System ◽  
Isotopic Composition ◽  
Carbonaceous Chondrite ◽  
Earth’S Crust ◽  
Outer Solar System ◽  
Volatile Elements ◽  
Earth’S Mantle ◽  
Isotopic Compositions ◽  
Enstatite Chondrite ◽  
Earth's Crust

The origin of Earth’s water remains unknown. Enstatite chondrite (EC) meteorites have similar isotopic composition to terrestrial rocks and thus may be representative of the material that formed Earth. ECs are presumed to be devoid of water because they formed in the inner Solar System. Earth’s water is therefore generally attributed to the late addition of a small fraction of hydrated materials, such as carbonaceous chondrite meteorites, which originated in the outer Solar System where water was more abundant. We show that EC meteorites contain sufficient hydrogen to have delivered to Earth at least three times the mass of water in its oceans. EC hydrogen and nitrogen isotopic compositions match those of Earth’s mantle, so EC-like asteroids might have contributed these volatile elements to Earth’s crust and mantle.

scholarly journals Comparison of Instruments and Methods of Positional Observations of the Sun and Major Planets

1986 ◽  
Vol 109 ◽  
pp. 685-689
Author(s):  
A.S. Kharin
Keyword(s):  
Solar System ◽  
Time Interval ◽  
The Sun ◽  
The World ◽  
Solar System Bodies ◽  
Available Information ◽  
Right Ascension

During the last decades, regular meridian observations of the Sun and major planets have been mainly carried out at Washington and Greenwich observatories. However, after 1960 position observations of Solar system bodies were initiated at many observatories throughout the world. The photographic and the equal altitude methods are widely used at this time, besides the meridian method. According to available information, during the time interval from 1960 to 1980,altogether 19 meridian instruments, 12 astrographs and 5 astrolabes took part in observations of the Sun and the major planets. More than 40.000 observations of single coordinates - right ascension and declinations have been obtained.

scholarly journals Faint solar analogues at the limit of no reddening

2019 ◽  
Vol 629 ◽  
pp. A33 ◽  
Author(s):  
R. E. Giribaldi ◽  
G. F. Porto de Mello ◽  
D. Lorenzo-Oliveira ◽  
E. B. Amôres ◽  
M. L. Ubaldo-Melo
Keyword(s):  
Principal Component Analysis ◽  
Solar System ◽  
Effective Temperature ◽  
Flux Distribution ◽  
Principal Component ◽  
Surface Gravity ◽  
The Sun ◽  
Spectral Indices ◽  
Atmospheric Parameters ◽  
Solar System Bodies

Context. The flux distribution of solar analogues is required for calculating the spectral albedo of solar system bodies such as asteroids and trans-Neptunian objects. Ideally a solar analogue should be comparatively faint as the target of interest, but very few analogues fainter than V = 9 mag have been identified so far. Only atmospheric parameters equal to solar guarantee a flux distribution equal to solar as well, while only photometric colours equal to solar do not. Reddening is also a factor to consider when selecting faint analogue candidates. Aims. Our aim is to implement the methodology for identifying faint analogues at the limit of precision allowed by the current spectroscopic surveys. We quantify the precision attainable for the atmospheric parameters of effective temperature (Teff), metallicity ([Fe/H]), and surface gravity (log g) when derived from moderately low-resolution (R = 8000) spectra with S∕N ~ 100. We estimate the significance of reddening at 100–300 pc from the Sun. Methods. We used the less precise photometry in the HIPPARCOS catalogue to select potential analogues with V ~ 10.5 mag (located at ~135 pc). We calibrated Teff and [Fe/H] as functions of equivalent widths of spectral indices by means of the principal component analysis regression. We derived log g, mass, radius, and age from the atmospheric parameters, Gaia parallaxes, and evolutionary tracks. We evaluated the presence of reddening for the candidates by underestimations of photometric Teff with respect to those derived by spectral indices. These determinations were validated with extinction maps. Results. We obtained the atmospheric parameters Teff, [Fe/H], and log g with precision of 97 K, 0.06 dex, 0.05 dex, respectively. From 21 candidates analysed, we identify five solar analogues: HIP 991, HIP 5811, and HIP 69477 have solar parameters within 1σ errors, and HIP 55619 and HIP 61835 within 2σ errors. Six other stars have Teff close to solar, but slightly lower [Fe/H]. Our analogues show no evidence of reddening except for four stars, that present E(B−V) ≥ 0.06 mag, translating to at least a 200 K decrease in photometric Teff.

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