scholarly journals Strong isotope effect in the VUV photodissociation of HOD: A possible origin of D/H isotope heterogeneity in the solar nebula

2021 ◽  
Vol 7 (30) ◽  
pp. eabg7775
Author(s):  
Zijie Luo ◽  
Yarui Zhao ◽  
Zhichao Chen ◽  
Yao Chang ◽  
Su-e Zhang ◽  
...  
Keyword(s):  
Solar System ◽  
Isotope Effect ◽  
Quantum State ◽  
Solar Nebula ◽  
Isotopic Fractionation ◽  
Branching Ratios ◽  
Terrestrial Planets ◽  
Isotopic Ratios ◽  
Alternative Source ◽  
Photochemical Models

The deuterium versus hydrogen (D/H) isotopic ratios are important to understand the source of water on Earth and other terrestrial planets. However, the determinations of D/H ratios suggest a hydrogen isotopic diversity in the planetary objects of the solar system. Photochemistry has been suggested as one source of this isotope heterogeneity. Here, we have revealed the photodissociation features of the water isotopologue (HOD) at λ = 120.8 to 121.7 nm. The results show different quantum state populations of OH and OD fragments from HOD photodissociation, suggesting strong isotope effect. The branching ratios of H + OD and D + OH channels display large isotopic fractionation, with ratios of 0.70 ± 0.10 at 121.08 nm and 0.49 ± 0.10 at 121.6 nm. Because water is abundant in the solar nebula, photodissociation of HOD should be an alternative source of the D/H isotope heterogeneity. This isotope effect must be considered in the photochemical models.

Boron Behavior During the Evolution of the Early Solar System: The First 180 Million Years

Elements ◽  
2017 ◽  
Vol 13 (4) ◽  
pp. 231-236 ◽  
Author(s):  
Charles K. Shearer ◽  
Steven B. Simon
Keyword(s):  
Solar System ◽  
Solar Nebula ◽  
Nuclear Reactions ◽  
Terrestrial Planets ◽  
The Sun ◽  
Planetary Formation ◽  
Light Elements ◽  
Early Solar System ◽  
Spallation Reactions ◽  
Magma Oceans

The behavior of boron during the early evolution of the Solar System provides the foundation for how boron reservoirs become established in terrestrial planets. The abundance of boron in the Sun is depleted relative to adjacent light elements, a result of thermal nuclear reactions that destroy boron atoms. Extant boron was primarily generated by spallation reactions. In the initial materials condensing from the solar nebula, boron was predominantly incorporated into plagioclase. Boron abundances in the terrestrial planets exhibit variability, as illustrated by B/Be. During planetary formation and differentiation, boron is redistributed by fluids at low temperature and during crystallization of magma oceans at high temperature.

scholarly journals Origin of uranium isotope variations in early solar nebula condensates

2016 ◽  
Vol 2 (3) ◽  
pp. e1501400 ◽  
Author(s):  
François L. H. Tissot ◽  
Nicolas Dauphas ◽  
Lawrence Grossman
Keyword(s):  
High Temperature ◽  
Solar System ◽  
Neutron Capture ◽  
Solar Nebula ◽  
Isotopic Fractionation ◽  
Uranium Isotope ◽  
Solar System Formation ◽  
System Composition ◽  
Isotopic Variations ◽  
Isotope Measurements

High-temperature condensates found in meteorites display uranium isotopic variations (235U/238U), which complicate dating the solar system’s formation and whose origin remains mysterious. It is possible that these variations are due to the decay of the short-lived radionuclide247Cm (t1/2= 15.6 My) into235U, but they could also be due to uranium kinetic isotopic fractionation during condensation. We report uranium isotope measurements of meteoritic refractory inclusions that reveal excesses of235U reaching ~+6% relative to average solar system composition, which can only be due to the decay of247Cm. This allows us to constrain the247Cm/235U ratio at solar system formation to (7.0 ± 1.6) × 10−5. This value provides new clues on the universality of the nucleosyntheticr-process of rapid neutron capture.

Exploring the Solar System

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Solar System ◽  
Planetary Systems ◽  
Interplanetary Dust ◽  
Terrestrial Planets ◽  
The Moon ◽  
System P ◽  
Asteroids And Comets

In this chapter, the author summarizes the properties of the Solar System, and how these were uncovered. Over centuries, the arrangement and properties of the Solar System were determined. The distinctions between the terrestrial planets, the gas and ice giants, and their various moons are discussed. Whereas humans have walked only on the Moon, probes have visited all the planets and several moons, asteroids, and comets; samples have been returned to Earth only from our moon, a comet, and from interplanetary dust. For Earth and Moon, seismographs probed their interior, whereas for other planets insights come from spacecraft and meteorites. We learned that elements separated between planet cores and mantels because larger bodies in the Solar System were once liquid, and many still are. How water ended up where it is presents a complex puzzle. Will the characteristics of our Solar System hold true for planetary systems in general?

scholarly journals Quantum Genetic Terrain Algorithm (Q-GTA): A Technique to Study the Evolution of the Earth Using Quantum Genetic Algorithm

Proceedings ◽  
2019 ◽  
Vol 46 (1) ◽  
pp. 26
Author(s):  
Pranjal Sharma ◽  
Ankit Agarwal ◽  
Bhawna Chaudhary
Keyword(s):  
Genetic Algorithm ◽  
Isotopic Fractionation ◽  
Volcanic Eruptions ◽  
Temperature Characteristic ◽  
Isotopic Ratios ◽  
Mantle Lithosphere ◽  
Monitoring Networks ◽  
Temperature Changes ◽  
Quantum Genetic Algorithm ◽  
The Earth

In recent years, geologists have put in a lot of effort trying to study the evolution of Earth using different techniques studying rocks, gases, and water at different channels like mantle, lithosphere, and atmosphere. Some of the methods include estimation of heat flux between the atmosphere and sea ice, modeling global temperature changes, and groundwater monitoring networks. That being said, algorithms involving the study of Earth’s evolution have been a debated topic for decades. In addition, there is distinct research on the mantle, lithosphere, and atmosphere using isotopic fractionation, which this paper will take into consideration to form genes at the former stage. This factor of isotopic fractionation could be molded in QGA to study the Earth’s evolution. We combined these factors because the gases containing these isotopes move from mantle to lithosphere or atmosphere through gaps or volcanic eruptions contributing to it. We are likely to use the Rb/Sr and Sm/Nd ratios to study the evolution of these channels. This paper, in general, provides the idea of gathering some information about temperature changes by using isotopic ratios as chromosomes, in QGA the chromosomes depict the characteristic of a generation. Here these ratios depict the temperature characteristic and other steps of QGA would be molded to study these ratios in the form of temperature changes, which would further signify the evolution of Earth based on the study that temperature changes with the change in isotopic ratios. This paper will collect these distinct studies and embed them into an upgraded quantum genetic algorithm called Quantum Genetic Terrain Algorithm or Quantum GTA.

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.

Late Accretion and the Origin of Water on Terrestrial Planets in the Solar System

2021 ◽  
Author(s):  
Cédric Gillmann ◽  
Gregor Golabek ◽  
Sean Raymond ◽  
Paul Tackley ◽  
Maria Schonbachler ◽  
...  
Keyword(s):  
Solar System ◽  
Long Term Evolution ◽  
Terrestrial Planets ◽  
Evolutionary Pathway ◽  
Giant Impact ◽  
The Earth ◽  
Term Evolution ◽  
Surface Liquid ◽  
Venus Atmosphere

<p>Terrestrial planets in the Solar system generally lack surface liquid water. Earth is at odd with this observation and with the idea of the giant Moon-forming impact that should have vaporized any pre-existing water, leaving behind a dry Earth. Given the evidence available, this means that either water was brought back later or the giant impact could not vaporize all the water.</p><p>We have looked at Venus for answers. Indeed, it is an example of an active planet that may have followed a radically different evolutionary pathway despite the similar mechanisms at work and probably comparable initial conditions. However, due to the lack of present-day plate tectonics, volatile recycling, and any surface liquid oceans, the evolution of Venus has likely been more straightforward than that of the Earth, making it easier to understand and model over its long term evolution.</p><p>Here, we investigate the long-term evolution of Venus using self-consistent numerical models of global thermochemical mantle convection coupled with both an atmospheric evolution model and a late accretion N-body delivery model. We test implications of wet and dry late accretion compositions, using present-day Venus atmosphere measurements. Atmospheric losses are only able to remove a limited amount of water over the history of the planet. We show that late accretion of wet material exceeds this sink. CO<sub>2</sub> and N<sub>2</sub> contributions serve as additional constraints.</p><p>Water-rich asteroids colliding with Venus and releasing their water as vapor cannot explain the composition of Venus atmosphere as we measure it today. It means that the asteroidal material that came to Venus, and thus to Earth, after the giant impact must have been dry (enstatite chondrites), therefore preventing the replenishment of the Earth in water. Because water can obviously be found on our planet today, it means that the water we are now enjoying on Earth has been there since its formation, likely buried deep in the Earth so it could survive the giant impact. This in turn suggests that suggests that planets likely formed with their near-full budget in water, and slowly lost it with time.</p>

scholarly journals Nitrogen and hydrogen fractionation in high-mass star-forming cores from observations of HCN and HNC

2018 ◽  
Vol 609 ◽  
pp. A129 ◽  
Author(s):  
L. Colzi ◽  
F. Fontani ◽  
P. Caselli ◽  
C. Ceccarelli ◽  
P. Hily-Blant ◽  
...  
Keyword(s):  
Solar System ◽  
Solar Nebula ◽  
Rotational Transition ◽  
High Mass ◽  
Evolutionary Stage ◽  
Mass Star ◽  
Stellar Cluster ◽  
Star Forming ◽  
Star Forming Regions ◽  
Dense Cores

The ratio between the two stable isotopes of nitrogen, 14N and 15N, is well measured in the terrestrial atmosphere (~272), and for the pre-solar nebula (~441, deduced from the solar wind). Interestingly, some pristine solar system materials show enrichments in 15N with respect to the pre-solar nebula value. However, it is not yet clear if and how these enrichments are linked to the past chemical history because we have only a limited number of measurements in dense star-forming regions. In this respect, dense cores, which are believed to be the precursors of clusters and also contain intermediate- and high-mass stars, are important targets because the solar system was probably born within a rich stellar cluster, and such clusters are formed in high-mass star-forming regions. The number of observations in such high-mass dense cores has remained limited so far. In this work, we show the results of IRAM-30 m observations of the J = 1−0 rotational transition of the molecules HCN and HNC and their 15N-bearing counterparts towards 27 intermediate- and high-mass dense cores that are divided almost equally into three evolutionary categories: high-mass starless cores, high-mass protostellar objects, and ultra-compact Hii regions. We have also observed the DNC(2–1) rotational transition in order to search for a relation between the isotopic ratios D/H and 14N/15N. We derive average 14N/15N ratios of 359 ± 16 in HCN and of 438 ± 21 in HNC, with a dispersion of about 150–200. We find no trend of the 14N/15N ratio with evolutionary stage. This result agrees with what has been found for N2H+ and its isotopologues in the same sources, although the 14N/15N ratios from N2H+ show a higher dispersion than in HCN/HNC, and on average, their uncertainties are larger as well. Moreover, we have found no correlation between D/H and 14N/15N in HNC. These findings indicate that (1) the chemical evolution does not seem to play a role in the fractionation of nitrogen, and that (2) the fractionation of hydrogen and nitrogen in these objects is not related.

Evolution of Comets into Asteroids?

1971 ◽  
Vol 12 ◽  
pp. 413-421 ◽  
Author(s):  
B.G. Marsden
Keyword(s):  
Solar Radiation ◽  
Solar Nebula ◽  
Oort Cloud ◽  
Original Version ◽  
Terrestrial Planets ◽  
Minor Planets ◽  
The Sun ◽  
Physical Difference ◽  
Short Period ◽  
The One

There has long been speculation as to whether comets evolve into asteroidal objects. On the one hand, in the original version of the Oort (1950) hypothesis, the cometary cloud was supposed to have formed initially from the same material that produced the minor planets; and an obvious corollary was that the main physical difference between comets and minor planets would be that the latter had long since lost their icy surfaces on account of persistent exposure to strong solar radiation (Öpik, 1963). However, following a suggestion by Kuiper (1951), it is now quite widely believed that, whereas the terrestrial planets and minor planets condensed in the inner regions of the primordial solar nebula, icy objects such as comets would have formed more naturally in the outer parts, perhaps even beyond the orbit of Neptune (Cameron, 1962; Whipple, 1964a). Furthermore, recent studies of the evolution of the short-period comets indicate that it is not possible to produce the observed orbital distribution from the Oort cloud, even when multiple encounters with Jupiter are considered (Havnes, 1970). We must now seriously entertain the possibility that most of the short-period orbits evolved directly from low-inclination, low-eccentricity orbits with perihelia initially in the region between, say, the orbits of Saturn and Neptune, and that these comets have never been in the traditional cloud at great distances from the Sun.

scholarly journals Planetary populations according to the orbital angular momentum

2009 ◽  
Vol 5 (S265) ◽  
pp. 420-421
Author(s):  
João A. S. Amarante ◽  
Helio J. Rocha-Pinto
Keyword(s):  
Angular Momentum ◽  
Solar System ◽  
Orbital Angular Momentum ◽  
Momentum Distribution ◽  
Semimajor Axis ◽  
Terrestrial Planets ◽  
Planetary Mass ◽  
Exoplanetary Systems ◽  
Planetary Migration ◽  
Two Populations

AbstractWe investigate the angular momentum distribution of known exoplanetary systems, as a function of the planetary mass, orbital semimajor axis and metallicity of the host star. We find exoplanets seems to be classified according to at least two ‘populations’, with respect to their angular momentum properties. This classification is independent on the composition of the planet and seems to be valid for both jovian and neptunian planets, and probably can be extrapolated to the terrestrial planets of the Solar System. We analyse these ‘populations’ considering the phenomenon of planetary migration.

scholarly journals Chemistry of the Solar System Revealed in the Interiors of the Giant Planets

2011 ◽  
Vol 7 (S280) ◽  
pp. 249-260 ◽  
Author(s):  
Jonathan I. Lunine
Keyword(s):  
Solar System ◽  
Microwave Radiometer ◽  
Giant Planets ◽  
Isotopic Ratios ◽  
Data Sets ◽  
Terrestrial Water ◽  
Galileo Probe ◽  
Probe Mission ◽  
Juno Mission

AbstractThe giant planets of our solar system contain a record of elemental and isotopic ratios of keen interest for what they tell us about the origin of the planets and in particular the volatile compositions of the solid phases. In situ measurements of the Jovian atmosphere performed by the Galileo Probe during its descent in 1995 demonstrate the unique value of such a record, but limited currently by the unknown abundance of oxygen in the interior of Jupiter–a gap planned to be filled by the Juno mission set to arrive at Jupiter in July of 2016. Our lack of knowledge of the oxygen abundance allows for a number of models for the Jovian interior with a range of C/O ratios. The implications for the origin of terrestrial water are briefly discussed. The complementary data sets for Saturn may be obtained by a series of very close, nearly polar orbits, at the end of the Cassini-Huygens mission in 2016-2017, and the proposed Saturn Probe. This set can only obtain what we have for Jupiter if the Saturn Probe mission carries a microwave radiometer.

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