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We investigate the evolution of the star formation rate in the early Galaxy using beryllium and oxygen abundances in metal poor stars. Specifically, we show that stars belonging to two previously identified kinematical classes (the…

天体物理学 · 物理学 2016-08-30 L. Pasquini , D. Galli , R. G. Gratton , P. Bonifacio , S. Randich , G. Valle

The recent observations of Be and B in metal poor stars has led to a reassessment of the origin of the light elements in the early Galaxy. At low it is metallicity ([O/H] < -1.75), it is necessary to introduce a production mechanism which…

天体物理学 · 物理学 2009-09-15 Brian D. Fields , Keith A. Olive , Michel Casse , Elisabeth Vangioni-Flam

We examine the evolution of Li in the Galactic disk,basing our model on the compilation of Li v.Fe observations in stars of iron abundance ranging between halo values,which give a baseline for the disk Li abundance,and 0.2 dex above…

天体物理学 · 物理学 2007-05-23 E , Casuso , J. E. Beckman

The dual origin of population II Li7, in both big bang nucleosynthesis and galactic cosmic-ray nucleosynthesis is discussed. It is argued that with additional Li6 data, stringent limits on the degree of Li7 depletion can be obtained. Li7…

天体物理学 · 物理学 2007-05-23 Keith A. Olive , Brian D. Fields

There are two accepted mechanisms to explain the origin of runaway OB-type stars: the Binary Supernova Scenario (BSS), and the Cluster Ejection Scenario (CES). In the former, a supernova explosion within a close binary ejects the secondary…

We review general characteristics of massive stars, present the main observable constraints that stellar models should reproduce. We discuss the impact of massive star nucleosynthesis on the early phases of the chemical evolution of the…

We present chemical evolution models aimed at reproducing the observed (N/O) vs. (O/H) abundance pattern of star forming galaxies in the Local Universe. We derive gas-phase abundances from SDSS spectroscopy and a complementary sample of…

星系天体物理 · 物理学 2016-03-23 Fiorenzo Vincenzo , Francesco Belfiore , Roberto Maiolino , Francesca Matteucci , Paolo Ventura

We discuss the highlights of our recent research, specifically the refractory vs. volatile interpretation of the rise of [O/Fe] with decreasing [Fe/H], and the issue of primary vs. secondary evolution of Be.

天体物理学 · 物理学 2016-11-03 R. Ramaty , R. E. Lingenfelter , B. Kozlovsky

Using the cosmological constants derived from WMAP, the standard big bang nucleosynthesis (SBBN) predicts the light elements primordial abundances for 4He, 3He, D, 6Li and 7Li. These predictions are in satisfactory agreement with the…

宇宙学与河外天体物理 · 物理学 2012-08-13 M. Spite , F. Spite , P. Bonifacio

We review the Galactic chemical evolution of Li6 and compare these results with recent observational determinations of the lithium isotopic ratio. In particular, we concentrate on so-called standard Galactic cosmic-ray nucleosynthesis in…

天体物理学 · 物理学 2009-10-31 Brian D. Fields , Keith A. Olive

We investigate the possibility that inhomogeneous nucleosynthesis may eventually be used to explain the abundances of \li6, \be9 and B in population II stars. The present work differs from previous studies in that we have used a more…

As all-solid-state batteries (SSBs) develop as an alternative to traditional cells, a thorough theoretical understanding of driving forces behind battery operation is needed. We present a fully first-principles-informed model of potential…

材料科学 · 物理学 2019-05-01 Michael W. Swift , Yue Qi

We discuss the 6Li abundance evolution within a hierarchical model of Galaxy formation which correctly reproduces the [Fe/H] distribution of metal-poor halo stars. Contrary to previous findings, we find that neither the level…

天体物理学 · 物理学 2011-11-10 Carmelo Evoli , Stefania Salvadori , Andrea Ferrara

We calculate the production rates of Li6, Li7, Be9, B10 and B11 via spallation of Carbon, Nitrogen and Oxygen nuclei by protons and alpha-particles and by alpha-alpha fusion reactions. We include recent measurements of the cross sections of…

天体物理学 · 物理学 2007-05-23 J. P. Kneller , J. R. Phillips , T. P. Walker

The abundance of O in planetary nebulae (PNe) has been historically used as a metallicity indicator of the interstellar medium (ISM) where they originated; e.g., it has been widely used to study metallicity gradients in our Galaxy and…

太阳与恒星天体物理 · 物理学 2016-03-09 D. A. Garcia-Hernandez , P. Ventura , G. Delgado-Inglada , F. Dell'Agli , M. Di Criscienzo , A. Yagüe

The determination of heavy element abundances from planetary nebula (PN) spectra provides an exciting opportunity to study the nucleosynthesis occurring in the progenitor asymptotic giant branch (AGB) star. We perform post-processing…

太阳与恒星天体物理 · 物理学 2015-05-14 Amanda I. Karakas , Maria Lugaro

Be abundances of old, low metallicity halo stars have major implications on cosmic-ray origin, requiring acceleration out of fresh supernova ejecta. The observed, essentially constant Be/Fe fixes the Be production per SNII, allowing the…

天体物理学 · 物理学 2007-05-23 Reuven Ramaty , Richard Lingenfelter

Based on a scenario of the inhomogeneous big-bang nucleosynthesis (IBBN), we investigate the detailed nucleosynthesis that includes the production of heavy elements beyond Li-7. From the observational constraints on light elements of He4…

宇宙学与河外天体物理 · 物理学 2013-07-08 Riou Nakamura , Masa-aki Hashimoto , Shin-ichiro Fujimoto , Nobuya Nishimura , Katsuhiko Sato

By virtue of their young age and intermediate mass, Herbig AeBe stars represent a cornerstone for our understanding of the mass-dependency of both the stellar and planetary formation processes. In this contribution, I review the current…

太阳与恒星天体物理 · 物理学 2015-06-23 Gaspard Duchene

A short overview is presented of current issues concerning the production and evolution of Li, Be and B in the Milky Way. It is argued that the currently popular idea that Galactic cosmic rays are accelerated inside metal-rich superbubbles…

天体物理学 · 物理学 2007-05-23 Nikos Prantzos