scholarly journals Neutron-captures in Low Mass Stars and the Early Solar System Record of Short-lived Radioactivities

2017 ◽  
Vol 165 ◽  
pp. 02003
Author(s):  
Maurizio Busso ◽  
Diego Vescovi ◽  
Oscar Trippella ◽  
Sara Palmerini ◽  
Sergio Cristallo ◽  
...  
Keyword(s):  
Solar System ◽  
Early Solar System ◽  
Low Mass Stars ◽  
Low Mass

The early Solar System and the rotation of the Sun

1984 ◽  
Vol 313 (1524) ◽  
pp. 39-45 ◽  
Keyword(s):  
Angular Momentum ◽  
Solar System ◽  
Magnetic Coupling ◽  
Central Star ◽  
The Sun ◽  
Early Solar System ◽  
Low Mass Stars ◽  
Hydrogen Burning ◽  
Low Mass ◽  
Solid Bodies

In most discussions of the formation of the Solar System, the early Sun is assumed to have possessed the bulk of the angular momentum of the system, and a closely surrounding disc of gas was spun out, which, through magnetic coupling, acquired a progressively larger proportion of the total angular momentum. There are difficulties with this model in accounting for the inclined axis of the Sun, the magnitude of the magnetic coupling required, and the nucleogenetic variations recently observed in the Solar System. Another possibility exists, namely that of a slowly contracting disc of interstellar material, leading to the formation of both a central star and a protoplanetary disc. In this model one can better account for the tilt of the Sun’s axis and the lack of mixing necessary to account for the nucleogenetic evidence. The low angular momentum of the Sun and of other low mass stars is then seen as resulting from a slow build-up as a degenerate dwarf, acquiring orbital material at a low specific angular momentum. When the internal temperature reaches the threshold for hydrogen burning, the star expands to the Main Sequence and is now a slow rotator. More massive stars would spin quickly because they had to acquire orbiting material after the expansion, and therefore at a high specific angular momentum. A process of gradual inward spiralling may also allow materials derived from different sources to accumulate into solid bodies, and be placed on a great variety of orbits in the outer reaches of the system, setting up the cometary cloud of uneven nucleogenetic composition.

scholarly journals Short-Lived Nuclei in the Early Solar System: A Low Mass Stellar Source?

2003 ◽  
Vol 20 (4) ◽  
pp. 356-370 ◽  
Author(s):  
M. Busso ◽  
R. Gallino ◽  
G. J. Wasserburg
Keyword(s):  
Solar System ◽  
Asymptotic Giant Branch ◽  
Early Solar System ◽  
Uncertainty Range ◽  
System A ◽  
Free Decay ◽  
Low Mass ◽  
Stellar Source ◽  
Review Current

AbstractWe discuss possible stellar origins of short-lived radioactive nuclei with meanlife τ ≤ 100 Myr, which were shown to be alive in the Early Solar System (ESS). We first review current ideas on the production of nuclides having 10 ≤ τ ≤ 100 Myr, which presumably derive from the continuous interplay of galactic astration, nucleosynthesis from massive supernovae and free decay in the interstellar medium. The abundance of the shorter lived 53Mn might be explained by this same scenario. Then we consider the nuclei 107Pd, 26Al, 41Ca and 60Fe, whose early solar system abundances are too high to have originated in this way. Present evidence favours a stellar origin, particularly for 107Pd, 26Al and 60Fe, rather than an in situ production by energetic solar particles. The idea of an encounter (rather close in time and space) between the forming Sun and a dying star is therefore discussed: this star may or may not have also triggered the solar formation. Recent nucleosynthesis calculations for the yields of the relevant short-lived isotopes and of their stable reference nuclei are discussed. Massive stars evolving to type II supernovae (either leaving a neutron star or a black hole as a remnant) seem incapable of explaining the four most critical ESS radioactivities in their observed abundance ratios. An asymptotic giant branch (AGB) star seems to be a viable source, especially if of relatively low initial mass (M ≤ 3 M⊙) and with low neutron exposure: this model can provide a solution for 26Al, 41Ca and 107Pd, with important contributions to 60Fe, which are inside the present uncertainty range of the 60Fe early solar system abundance. Such a model requires that 26Al is produced substantially on the AGB by cool bottom processing. The remaining inventory of short-lived species in the solar nebula would then be attributed to the continuous galactic processing, with the exception of 10Be, which must reflect production by later proton bombardment at a low level during early solar history.

scholarly journals The effects of stellar winds and magnetic fields on exoplanets

2013 ◽  
Vol 9 (S302) ◽  
pp. 228-236 ◽  
Author(s):  
A. A. Vidotto
Keyword(s):  
Solar System ◽  
Interplanetary Medium ◽  
Great Majority ◽  
Stellar Winds ◽  
Stellar Rotation ◽  
Low Mass Stars ◽  
Exoplanetary Systems ◽  
Cool Stars ◽  
Low Mass ◽  
Host Stars

AbstractThe great majority of exoplanets discovered so far are orbiting cool, low-mass stars whose properties are relatively similar to the Sun. However, the stellar magnetism of these stars can be significantly different from the solar one, both in topology and intensity. In addition, due to the present-day technology used in exoplanetary searches, most of the currently known exoplanets are found orbiting at extremely close distances to their host stars (< 0.1 au). The dramatic differences in stellar magnetism and orbital radius can make the interplanetary medium of exoplanetary systems remarkably distinct from that of the Solar System. To constrain interactions between exoplanets and their host-star's magnetised winds and to characterise the interplanetary medium that surrounds exoplanets, more realistic stellar wind models, which account for factors such as stellar rotation and the complex stellar magnetic field configurations of cool stars, must be employed. Here, I briefly review the latest progress made in data-driven modelling of magnetised stellar winds. I also show that the interaction of the stellar winds with exoplanets can lead to several observable signatures, some of which that are absent in our own Solar System.

scholarly journals s-Process Enrichment in Low-Mass Agb Stars

1989 ◽  
Vol 106 ◽  
pp. 176-195 ◽  
Author(s):  
R. Gallino
Keyword(s):  
Solar System ◽  
Massive Stars ◽  
Agb Stars ◽  
Intermediate Mass ◽  
Low Mass Stars ◽  
Temporal Behaviour ◽  
Physical Conditions ◽  
Intermediate Mass Stars ◽  
Low Mass ◽  
Main Component

AbstractAfter a brief description of the developments of the theory of s-process nucleosynthesis, the difficulties recently encountered in envisaging reliable astrophysical conditions for obtaining a solar-system distribution of s-isotopes are discussed. In particular, while the reaction 22Ne(α, n)25Mg may account for the nucleosynthesis of the weak s-component in massive stars, it fails to reproduce the main s-component in intermediate mass stars. The efficiency of the alternative reaction 13C(α, n)160 occurring in low mass stars during recurring thermal instabilities of the He shell is then analyzed. It is shown that, contrary to previous expectations, the 13C source well reproduces the main component, provided that realistic physical conditions are assumed for the temporal behaviour of the pulse and the effect of the light n-absorbers (especially 12C) is properly taken into account. The results satisfactorily compare with the constraints of the classical s-analysis. Key observational evidences also appear to be in agreement with this scenario.

scholarly journals Magnetised winds of low-mass stars and their impact on exoplanets

2013 ◽  
Vol 8 (S300) ◽  
pp. 322-329
Author(s):  
A. A. Vidotto
Keyword(s):  
Solar System ◽  
Interplanetary Medium ◽  
Great Majority ◽  
Stellar Winds ◽  
Low Mass Stars ◽  
Exoplanetary Systems ◽  
Weather Events ◽  
Low Mass ◽  
The One ◽  
Host Stars

AbstractThe proper characterisation of stellar winds is crucial to constrain interactions between exoplanets and their surrounding environments and also essential for the study of space weather events on exoplanets. Although the great majority of exoplanets discovered so far are orbiting cool, low-mass stars with properties (mass, radius and effective temperatures) similar to solar, the stellar magnetism can be significantly different from the solar one, both in topology and intensity. Due to the current technology used in exoplanetary searches, most of the currently known exoplanets are found orbiting at extremely close distances to their host stars (< 0.1 au). The dramatic differences in stellar magnetism and orbital radius can make the interplanetary medium of exoplanetary systems remarkably distinct from the one present in the solar system. In addition, the interaction of the stellar winds with exoplanets can lead, among others, to observable signatures that are absent in our own solar system.

Laboratory and in-situ analysis of comet dust

1988 ◽  
Vol 46 ◽  
pp. 8-9
Author(s):  
D.E. Brownlee ◽  
A.L. Albee
Keyword(s):  
Electron Microscopy ◽  
Solar System ◽  
Laboratory Study ◽  
Isotopic Analysis ◽  
Building Blocks ◽  
Sem Analysis ◽  
Early Solar System ◽  
Cometary Material ◽  
Comet Dust

Comets are primitive, kilometer-sized bodies that formed in the outer regions of the solar system. Composed of ice and dust, comets are generally believed to be relic building blocks of the outer solar system that have been preserved at cryogenic temperatures since the formation of the Sun and planets. The analysis of cometary material is particularly important because the properties of cometary material provide direct information on the processes and environments that formed and influenced solid matter both in the early solar system and in the interstellar environments that preceded it.The first direct analyses of proven comet dust were made during the Soviet and European spacecraft encounters with Comet Halley in 1986. These missions carried time-of-flight mass spectrometers that measured mass spectra of individual micron and smaller particles. The Halley measurements were semi-quantitative but they showed that comet dust is a complex fine-grained mixture of silicates and organic material. A full understanding of comet dust will require detailed morphological, mineralogical, elemental and isotopic analysis at the finest possible scale. Electron microscopy and related microbeam techniques will play key roles in the analysis. The present and future of electron microscopy of comet samples involves laboratory study of micrometeorites collected in the stratosphere, in-situ SEM analysis of particles collected at a comet and laboratory study of samples collected from a comet and returned to the Earth for detailed study.

Preface: Evolution of the early solar system: Presolar cosmochemical fingerprints and the formation of watery rocky planets

2016 ◽  
Vol 50 (1) ◽  
pp. 1-2 ◽  
Author(s):  
Tomohiro Usui ◽  
Audrey Bouvier ◽  
Justin I. Simon ◽  
Noriko Kita
Keyword(s):  
Solar System ◽  
Early Solar System ◽  
Rocky Planets

A nearby neutron-star merger explains the actinide abundances in the early Solar System

Nature ◽  
2019 ◽  
Vol 569 (7754) ◽  
pp. 85-88 ◽  
Author(s):  
Imre Bartos ◽  
Szabolcs Marka
Keyword(s):  
Neutron Star ◽  
Solar System ◽  
Early Solar System

scholarly journals Ages of Galactic and Extragalactic Star Clusters of Various Abundances

1983 ◽  
Vol 6 ◽  
pp. 109-117 ◽  
Author(s):  
R.D. Cannon
Keyword(s):  
Star Clusters ◽  
Magellanic Clouds ◽  
Open Clusters ◽  
Simultaneous Solution ◽  
Low Mass Stars ◽  
Cluster Systems ◽  
Distant Cluster ◽  
Low Mass

In this review I shall concentrate mainly on globular star clusters in our Galaxy since these are the objects for which most work has been done recently, both observationally and theoretically. However, I shall also discuss briefly the oldest open clusters and clusters in the Magellanic Clouds. Little can be said about more distant cluster systems, since the only observations available are of integrated colours or spectra and these seem to be rather unreliable indicators of age. It is perhaps worth pointing out that the title may be slightly misleading; the problem is not so much to determine the ages of clusters of known abundances, as to obtain the best simultaneous solution for both age and composition, since some of the most important abundances (notably helium and oxygen) are virtually unobservable in little-evolved low mass stars.

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