DOCSLIB.ORG

The Abundance of Lithium Measured for the First Time Beyond Our Galaxy

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Abundance of Lithium Measured for the First Time Beyond Our Galaxy Astronomical Science The Abundance of Lithium Measured for the First Time Beyond Our Galaxy Alessio Mucciarelli1 In a seminal paper, Spite & Spite (1982) utes after the Big Bang. In fact, if the Maurizio Salaris2 first noted that dwarf Population II stars primordial lithium abundance derived Piercarlo Bonifacio3 in the Solar Neighbourhood (with from the CMB results is incorrect, the Lorenzo Monaco4 [Fe/H] < –1.5 and effective temperatures current SBBN model would have to be Sandro Villanova5 > 5800 K) share the same lithium abun- drastically re-thought, introducing “new dance, regardless of their metallicity physics”, e.g., the inclusion of “new” high- and temperature, a feature known as the energy, non-thermal particles and the 1 Dipartimento di Fisica & Astronomia, Spite Plateau. The derived lithium abun- annihilation/decay of dark matter Universitá degli Studi di Bologna, Italy dance turns out to be in the range particles. On the other hand, if the initial 2 Astrophysics Research Institute, A(Li) = 2.1–2.4 dex, depending on the lithium content in Population II stars is Liverpool John Moores University, adopted temperature scale. The existence depleted by transport processes, the Liverpool, United Kingdom of a narrow lithium plateau has been measurement of the lithium abundance 3 GEPI, Observatoire de Paris, CNRS, confirmed by three decades of observa- in these stars could provide robust con- Univ. Paris Diderot, Meudon, France tions, both in halo field stars and in glob- straints on the efficiency of turbulent 4 ESO ular cluster stars. mechanisms occurring at the bottom of 5 Universidad de Concepcion, Casilla, the stellar convective envelope (which Concepcion, Chile The results obtained with the Wilkinson is a free parameter in the stellar models). Microwave Anisotropy Probe (WMAP; Spergel et al., 2007) and Planck (Planck The discrepancy between the primor- collaboration, 2013) satellites have pro- An alternative route: The lower RGB stars dial lithium abundance derived from vided an alternative route to inferring Population II dwarf stars and from the ΩB. In fact, these high precision measure- Mucciarelli, Salaris & Bonifacio (2012) predictions of standard Big Bang ments of the cosmic microwave back- proposed an alternative/complementary nucleosynthesis is one of the most ground (CMB) have allowed ΩB to be esti- route to investigate the initial lithium intriguing and challenging open ques- mated with unprecedented accuracy. abundance in Population II stars (with tions in modern astrophysics. The The derived value of ΩB, coupled with the respect to the observations of dwarf use of lower red giant branch stars, standard Big Bang nucleosynthesis stars), by measuring the surface lithium instead of the usual method of observ- (SBBN) model, provided a lithium abun- abundance in lower red giant branch ing dwarf stars, represents a new dance of 2.72 ± 0.06 dex (Coc et al., (RGB) stars. These stars are defined as approach to attacking the problem. 2013). This value is significantly higher, by the giants evolving between the first Lithium in distant, extragalactic stellar at least a factor of three, than the lithium dredge-up and the luminosity level of the systems, for which observations of abundance derived from dwarf stars. RGB Bump. When a star evolves off the dwarf stars are precluded because of Such a discrepancy is referred to as the main sequence, the convection propa- their faintness, becomes open for cosmological lithium problem. gates inward (first dredge-up) reaching investigation. From observations with hot regions where lithium has been FLAMES at the VLT, we have been At present, the discrepancy between the burned. Lithium-free material is dredged able to derive for the first time the initial Spite Plateau and the CMB + SBBN up to the surface, with the main effect of lithium abundance in an extragalactic results is still unexplained. Three possible reducing the surface lithium abundance. globular cluster, namely M54 in the explanations appear to be especially When the convective envelope attains Sagittarius galaxy. promising: its maximum penetration, depletion of the 1) the effect of atomic diffusion and surface lithium abundance ends. After- some competing additional mixing, the wards the lithium abundance remains Lithium, together with hydrogen and combined effect of which decreases constant until the star reaches the lumi- helium, is synthesised during the early the lithium abundances in the atmos- nosity level of the RGB Bump; then, an phase of the Universe, in the first few pheres of dwarf stars (see e.g., Korn et additional mixing episode occurs, further minutes after the Big Bang. All the ele- al., 2006); reducing the surface lithium abundance ments heavier than lithium are produced 2) inadequacies in the SBBN models used down to virtually zero, or to effectively later, mainly during the nucleosynthesis to calculate the lithium abundance non-measurable values (see Figure 1). occurring in the stellar interiors. In par- (Iocco et al., 2009); ticular, the primordial lithium abundance 3) lithium depletion driven by Population II The lower RGB stars (both in the Galactic is strictly linked to the baryonic density stars during early Galaxy evolution field and globular clusters) display a (ΩB), a cosmological parameter that (Piau et al., 2006). constant lithium abundance, defining a quantifies the amount of ordinary matter. plateau that mirrors the Spite Plateau, but Hence, the study of the lithium abun- Whatever the solution of the lithium at a lower abundance (A(Li) ~ 0.9–1.0 dance in the oldest stars is crucial for problem is, the investigation of this dis- dex). Since the amount of lithium deple- several different astrophysical topics, crepancy (and its solution) is a formidable tion after the first dredge-up can be pre- i.e., cosmology, stellar evolution and chance to understand SBBN in greater dicted easily from stellar models, the globular cluster formation. depth and refine our description of the lithium abundance measured among the processes occurring in the first few min- lower RGB stars can be used to infer or The Messenger 158 – December 2014 45 Astronomical Science Mucciarelli A. et al., Lithium Measured for the First Time Beyond Our Galaxy ",! 2!!- 2OHSD/K@SD@T TW +NVDQ1&! Ck 3$ -+ +H -NQL@KHRD %HQRS #QDCFDlTO 1&!!TLO KNF++ी 6@UDKDMFSGÄ Figure 1. Behaviour of the surface lithium abundance Figure 2. The observed lithium doublet of the aver- as a function of luminosity for the stars in the globular age spectrum obtained by combining 51 member cluster M4 (from Mucciarelli et al., 2011). The value stars of M54 observed with FLAMES GIRAFFE. of the initial lithium abundance as derived by the CMB Superimposed are the best-fit synthetic spectrum + SBBN is marked as a blue dashed line. The value and two synthetic spectra calculated with lithium of the lithium abundance as derived from dwarf stars abundance variations of ± 0.2 dex. (the Spite Plateau) is marked by the blue solid line. constrain the initial lithium abundance of where the observation of dwarf stars is Figure 2 shows the lithium doublet at those stars. precluded because of their distance. 6707 Å observed in an average spectrum, obtained by combining together the spec- This new diagnostic has extraordinary tra of the 51 stars, in order to enhance potential and advantages. In particular: Lithium abundance in M54 the spectral quality. Superimposed are 1) The derived abundance of lithium is the best-fit synthetic spectrum and two totally independent of the abundances We have recently approached the lithium synthetic spectra calculated with lithium obtained from dwarf stars and there- problem by adopting this new diagnostic. abundance variations of ± 0.2 dex. fore does not suffer from the large We used the lower RGB stars to investi- uncertainties on the turbulent mixing gate for the first time the lithium abun- We measured A(Li) = 0.93 ± 0.11 dex, affecting that evolutionary stage. Note dance outside the Milky Way (Mucciarelli in agreement with measurements in that the uncertainties related to the effi- et al., 2014). We obtained high-resolution lower RGB stars of the Galactic Halo. By ciency of diffusion processes amount spectra of 51 member stars of the globu- considering the dilution due to the first to 0.4 dex or more for the lithium abun- lar cluster M54, with the FLAMES facility dredge-up, we established that the initial dance in dwarf stars, while they are mounted at the Kueyen Unit Telescope of lithium abundance of this stellar system smaller than 0.07 dex for lower RGB the Very Large Telescope (VLT) and the (in the range A(Li) = 2.29–2.35 dex) was stars; GIRAFFE spectrometer. M54 is a massive compatible with those derived in dwarf 2) The use of lower RGB stars will allow globular cluster located at ~ 25 kpc from stars. This is the most distant measure- estimates of the lithium content in the Sun and immersed in the nucleus ment of the initial lithium abundance in stellar populations more distant than of the Sagittarius dwarf galaxy. The dwarf old, metal-poor stars obtained so far. In those usually observed to investigate stars in M54 and the Sagittarius galaxy fact, all the previous studies of the lithium the Spite Plateau. The obvious benefits are too faint (at V ~ 22 mag) to measure abundance in dwarf stars are restricted are not only to enlarge the sample of their lithium abundance, even with the to distances within ~ 8 kpc from the Sun. Galactic field and cluster stars to study VLT, hence the study of lower RGB stars the primordial lithium abundance, but currently represents the only possible Figure 3 summarises the state of the also to offer the formidable opportuni- route to infer the lithium abundance in art of our current knowledge of the ties to investigate the initial lithium this galaxy.
Load more

Recommended publications
  • Near-Field Cosmology with Extremely Metal-Poor Stars
    AA53CH16-Frebel ARI 29 July 2015 12:54 Near-Field Cosmology with Extremely Metal-Poor Stars Anna Frebel1 and John E. Norris2 1Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; email: [email protected] 2Research School of Astronomy & Astrophysics, The Australian National University, Mount Stromlo Observatory, Weston, Australian Capital Territory 2611, Australia; email: [email protected] Annu. Rev. Astron. Astrophys. 2015. 53:631–88 Keywords The Annual Review of Astronomy and Astrophysics is stellar abundances, stellar evolution, stellar populations, Population II, online at astro.annualreviews.org Galactic halo, metal-poor stars, carbon-enhanced metal-poor stars, dwarf This article’s doi: galaxies, Population III, first stars, galaxy formation, early Universe, 10.1146/annurev-astro-082214-122423 cosmology Copyright c 2015 by Annual Reviews. All rights reserved Abstract The oldest, most metal-poor stars in the Galactic halo and satellite dwarf galaxies present an opportunity to explore the chemical and physical condi- tions of the earliest star-forming environments in the Universe. We review Access provided by California Institute of Technology on 01/11/17. For personal use only. the fields of stellar archaeology and dwarf galaxy archaeology by examin- Annu. Rev. Astron. Astrophys. 2015.53:631-688. Downloaded from www.annualreviews.org ing the chemical abundance measurements of various elements in extremely metal-poor stars. Focus on the carbon-rich and carbon-normal halo star populations illustrates how these provide insight into the Population III star progenitors responsible for the first metal enrichment events. We extend the discussion to near-field cosmology, which is concerned with the forma- tion of the first stars and galaxies, and how metal-poor stars can be used to constrain these processes.
    [Show full text]
  • Initial Li Abundances in the Protogalaxy and Globular Clusters
    Draft version April 18, 2019 Typeset using LATEX preprint style in AASTeX62 Initial Li Abundances in the Protogalaxy and Globular Clusters Based upon the Chemical Separation and Hierarchical Structure Formation Motohiko Kusakabe1 and Masahiro Kawasaki2,3 1School of Physics, and International Research Center for Big-Bang Cosmology and Element Genesis, Beihang University, 37, Xueyuan Road, Haidian-qu, Beijing 100083, People’s Republic of China 2Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan 3Kavli IPMU (WPI), UTIAS, the University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8583, Japan (Received xxx, 2018; Revised xxx, 2018; Accepted xxx, 2018) ABSTRACT The chemical separation of Li+ ions induced by a magnetic field during the hierarchical structure formation can reduce initial Li abundances in cosmic structures. It is shown that cosmological reionization of neutral Li atoms quickly completes as soon as the first star is formed. Since almost all Li is singly ionized during the main course of structure formation, it can efficiently separate from gravitationally collapsing neutral gas. The separation is more efficient in smaller structures which formed earlier. In the framework of the hierarchical structure formation, extremely metal-poor stars can have smaller Li abundances because of their earlier formations. It is found that the chemical separation by a magnetic field thus provides a reason that Li abundances in extremely metal-poor stars are lower than the Spite plateau and have a large dispersion as well as an explanation of the Spite plateau itself. In addition, the chemical separation scenario can explain Li abundances in NGC 6397 which are higher than the Spite plateau.
    [Show full text]
  • The Metal-Poor End of the Spite Plateau I
    A&A 522, A26 (2010) Astronomy DOI: 10.1051/0004-6361/200913282 & c ESO 2010 Astrophysics The metal-poor end of the Spite plateau I. Stellar parameters, metallicities, and lithium abundances,, L. Sbordone1,2,3,P.Bonifacio1,2,4,E.Caffau2, H.-G. Ludwig1,2,5,N.T.Behara1,2,6, J. I. González Hernández1,2,7, M. Steffen8,R.Cayrel2,B.Freytag9, C. Van’t Veer2,P.Molaro4,B.Plez10, T. Sivarani11, M. Spite2, F. Spite2,T.C.Beers12, N. Christlieb5,P.François2, and V. Hill2,13 1 CIFIST Marie Curie Excellence Team, France 2 GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, Place Jules Janssen, 92190 Meudon, France 3 Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany e-mail: [email protected] 4 INAF – Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34143 Trieste, Italy 5 Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, Königstuhl 12, 69117 Heidelberg, Germany 6 Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles, CP 226, boulevard du Triomphe, 1050 Bruxelles, Belgium 7 Dpto. de Astrofísica y Ciencias de la Atmósfera, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain 8 Astrophysikalisches Institut Potsdam An der Sternwarte 16, 14482 Potsdam, Germany 9 Centre de Recherche Astrophysique de Lyon, UMR 5574: Université de Lyon, École Normale Supérieure de Lyon, 46 allée d’Italie, 69364 Lyon Cedex 07, France 10 Université Montpellier 2, CNRS, GRAAL, 34095 Montpellier, France 11 Indian Institute of Astrophysiscs, II Block, Koramangala, Bangalore 560 034, India 12 Dept. if Physics & Astronomy, and JINA: Joint Insrtitute for Nuclear Astrophysics, Michigan State University, E.
    [Show full text]
  • Cosmological Lithium Problems
    EPJ Web of Conferences 184, 01002 (2018) https://doi.org/10.1051/epjconf/201818401002 9th European Summer School on Experimental Nuclear Astrophysics Cosmological Lithium Problems C.A. Bertulani1,�, Shubhchintak1,��, and A.M. Mukhamedzhanov2,��� 1Department of Physics and Astronomy, Texas A&M University-Commerce, Commerce, TX 75429, USA 2Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA Abstract. We briefly describe the cosmological lithium problems followed by a summary of our recent theoretical work on the magnitude of the effects of electron screening, the possible existence of dark matter parallel universes and the use of non-extensive (Tsal- lis) statistics during big bang nucleosynthesis. Solutions within nuclear physics are also discussed and recent measurements of cross-sections based on indirect experimental tech- niques are summarized. 1 Introduction The cosmological lithium problem has become one of the most intriguing open questions in cos- mology due to inconsistencies between observation and calculations based on the standard Big Bang nucleosynthesis (BBN) for the primordial elemental abundances. The BBN model contains a few parameters such as the baryon-to-photon ratio η = nb/nγ, the neutron decay time τn, and the number of neutrino families Nν (see, for instance, Ref. [1]). The parameter η relates to the baryon density of the universe by means of Ω h2 (η/10 10)/273, with the Hubble dimensionless parameter h defined 0 � − through the relation H0 = 100h km/s/Mpc, the index ‘0’ meaning present time. The anisotropies of the cosmic microwave radiation (CMB) independently determine the value of η [2, 3] when the uni- verse was about 0.3 Myr after the Big Bang.
    [Show full text]
  • Evolution of Low Mass Stars: Lithium Problem and -Enhanced Tracks and Isochrones
    SISSA - International School for Advanced Studies Evolution of low mass stars: lithium problem and α-enhanced tracks and isochrones Dissertation Submitted for the Degree of “Doctor Philosophiæ” Supervisors Candidate arXiv:1702.02932v1 [astro-ph.SR] 9 Feb 2017 Prof. Alessandro Bressan Xiaoting FU Dr. Paolo Molaro Dr. Leo´ Girardi October 2016 ii We are the dust of stars. Contents Abstract iii Acronyms v 1 Introduction 1 1.1 Historic progress in understanding stars .............. 1 1.2 Modern stellar evolution models .................. 4 1.2.1 Equations of stellar structure and evolution ........ 5 1.2.2 Boundary conditions .................... 7 1.2.3 Opacity ........................... 8 1.2.4 PARSEC (PAdova and TRieste Stellar Evolution Code) .. 11 1.2.5 Other stellar models .................... 12 1.3 Solar-scaled mixture and α enhancement .............. 15 1.4 Lithium in stars, origin and problems ................ 16 1.4.1 Cosmological lithium problem ............... 17 I PARSEC tracks and isochrones with α enhancement 23 2 Input physics 27 2.1 Nuclear reaction rates ........................ 27 2.2 Equations of state .......................... 29 2.3 Solar model ............................. 30 2.4 α enhancement ........................... 34 2.5 Helium content ........................... 35 3 Calibration with 47Tuc 37 3.1 Metal mixtures ........................... 38 3.2 Isochrones fitting and Luminosity function ............. 47 3.2.1 Low main sequence to turn-off ............... 47 3.2.2 RGB bump and envelope overshooting calibration .... 49 i ii CONTENTS 3.2.3 Red Giant Branch ...................... 57 3.2.4 Horizontal Branch morphology .............. 66 4 RGB bump comparison with other GC data and models 79 4.1 Comparison with other models ................... 79 4.2 Comparison with other GC data .................
    [Show full text]
  • Lithium in Very Metal-Poor Dwarf Stars - Problems for Standard Big Bang Nucleosynthesis?
    Lithium in Very Metal-poor Dwarf Stars - Problems for Standard Big Bang Nucleosynthesis? David L. Lambert The W.J. McDonald Observatory, University of Texas, Austin, Texas, USA Abstract. The standard model of primordial nucleosynthesis by the Big Bang as selected by the WMAP-based estimate of 2 7 the baryon density (Ωbh ) predicts an abundance of Li that is a factor of three greater than the generally reported abundance for stars on the Spite plateau, and an abundance of 6Li that is about a thousand times less than is found for some stars on the plateau. This review discusses and examines these two discrepancies. They can likely be resolved without major surgery on the standard model of the Big Bang. In particular, stars on the Spite plateau may have depleted their surface lithium abundance over their long lifetime from the WMAP-based predicted abundances down to presently observed abundances, and synthesis 6 7 of Li (and Li) via α · α fusion reactions may have occurred in the early Galaxy. Yet, there remain fascinating ways in which to remove the two discrepancies involving aspects of a new cosmology, particularly through the introduction of exotic particles. INTRODUCTION Observers and theoreticians have long regarded Big Bang nucleosynthesis as providing a simple testable set of reliable predictions with one free parameter to be determined by observations of the primordial relative abundances of the 1 2 3 4 7 2 light nuclides H, H, He, He, and Li. That free parameter is the baryonic density Ωbh or, equivalently, the number 2 7 1 ¢ density ratio of baryons to photons η: Ω bh 3 652 10 η where h is the Hubble constant in units of 100 km s Mpc 1.
    [Show full text]
  • Arxiv:2011.02659V2 [Astro-Ph.GA] 4 Jul 2021 Samples of Halo and Disk Stars
    MNRAS 000,1–12 (2021) Preprint 6th July 2021 Compiled using MNRAS LATEX style file v3.0 The GALAH Survey: Accreted stars also inhabit the Spite Plateau Jeffrey D. Simpson,1,2¢ Sarah L. Martell,1,2 Sven Buder,2,3 Joss Bland-Hawthorn,2,4 Andrew R. Casey,5,6 Gayandhi M. De Silva,7,8 Valentina D’Orazi,9 Ken C. Freeman,2,3 Michael Hayden,2,4 Janez Kos,10 Geraint F. Lewis,4 Karin Lind,11 Katharine J. Schlesinger,3 Sanjib Sharma,2,4 Dennis Stello,1,2,4 Daniel B. Zucker,2,8,12 Tomaž Zwitter,10 Martin Asplund,13 Gary Da Costa,2,3 Klemen Čotar,10 Thor Tepper-García,2,4,14 Jonathan Horner,15 Thomas Nordlander,2,3 Yuan-Sen Ting,3,16,17,18 Rosemary F. G. Wyse19 and The GALAH Collaboration 1School of Physics, UNSW, Sydney, NSW 2052, Australia 2Centre of Excellence for Astrophysics in Three Dimensions (ASTRO-3D), Australia 3Research School of Astronomy & Astrophysics, Australian National University, ACT 2611, Australia 4Sydney Institute for Astronomy, School of Physics, A28, The University of Sydney, NSW, 2006, Australia 5School of Physics and Astronomy, Monash University, Clayton, VIC 3800, Australia 6Monash Centre for Astrophysics, School of Physics and Astronomy, Monash University, Australia 7Australian Astronomical Optics, Faculty of Science and Engineering, Macquarie University, Macquarie Park, NSW 2113, Australia 8Macquarie University Research Centre for Astronomy, Astrophysics & Astrophotonics, Sydney, NSW 2109, Australia 9Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 5, 35122, Padova, Italy 10Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia 11Department of Astronomy, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm, Sweden 12Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109, Australia 13Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str.
    [Show full text]
  • The Cosmological Lithium Problem Outside the Galaxy: the Sagittarius Globular Cluster M54 !
    Mon. Not. R. Astron. Soc. 000,000–000(0000) Printed28July2014 (MNLaTEXstylefilev2.2) The cosmological Lithium problem outside the Galaxy: the Sagittarius globular cluster M54 ! A. Mucciarelli,1 M. Salaris,2,P.Bonifacio3,L.Monaco4 and S. Villanova5 1Dipartimento di Fisica & Astronomia, Universit`adegliStudidiBologna,VialeBertiPichat,6/2-40127,Bologna,Italy 2Astrophysics Research Institute, Liverpool John Moores University, IC2, 146 Brownlow Hill, Liverpool L3 5RF, United Kingdom 3GEPI, Observatoire de Paris, CNRS, Univ. Paris Diderot, 92125, Meudon Cedex, France 4European Southern Observatory, Casilla 19001, Santiago, Chile 5Universidad de Concepcion, Casilla 160-C, Concepcion, Chile 28 July 2014 ABSTRACT The cosmological Li problem is the observed discrepancy between Li abundance (A(Li)) measured in Galactic dwarf, old and metal-poor stars (traditionally assumed to be equal to the initial value A(Li)0), and that predicted by standard Big Bang Nucleosynthesis calculations (A(Li)BBN ). Here we attack the Li problem by consid- ering an alternative diagnostic, namely the surface Li abundance of red giant branch stars that in a colour magnitude diagram populate the region between the completion of the first dredge-up and the red giant branch bump. We obtained high-resolution spectra with the FLAMES facility at the Very Large Telescope for a sample of red giants in the globular cluster M54, belonging to the Sagittarius dwarf galaxy. We ob- tain A(Li)= 0.93 0.11 dex, translating – after taking into account the dilution due ± to the dredge up– to initial abundances (A(Li)0) in the range 2.35–2.29 dex, depend- ing on whether or not atomic diffusion is considered.
    [Show full text]
  • Cosmological Implications of Light Element Abundances: Theory DAVID N
    Proc. Natl. Acad. Sci. USA Vol. 90, pp. 4782-4788, June 1993 Colloquium Paper This paper was presented at a colloquium entitled "Physical Cosmology," organized by a committee chaired by David N. Schramm, held March 27 and 28, 1992, at the National Academy of Sciences, Irvine, CA. Cosmological implications of light element abundances: Theory DAVID N. SCHRAMM Astronomy and Astrophysics Centers 140, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; and National Aeronautic and Space Administration/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Box 500, Batavia, IL 60510-0500 ABSTRACT Primordial nucleosynthesis provides (with number of neutrino families and its subsequent verification the microwave background radiation) one of the two quanti- by the Large Electron Positron Collider (LEP) and the tative experimental tests of the hot Big Bang cosmological Stanford Linear Collider (SLC). model (versus alternative explanations for the observed Hubble Also discussed is the possibility that a first-order quark- expansion). The standard homogeneous-isotropic calculation hadron phase transition could have produced variations from fits the light element abundances ranging from 'H at 76% and the standard homogeneous model. It will be shown that 4He at 24% by mass through 2H and 3He at parts in 105 down contrary to initial indications, first-order quark-hadron- to 7Li at parts in 1010. It is also noted how the recent Large inspired results are consistent with the homogeneous model Electron Positron Collider (and Stanford Linear Collider) results. results on the number of neutrinos (N,,) are a positive labora- Finally, a discussion of the recent B and Be observations tory test of this standard Big Bang scenario.
    [Show full text]
  • Challenges to the Standard Model of Big Bang Nucleosynthesis GARY STEIGMAN Departments of Physics and Astronomy, the Ohio State University, Columbus, OH 43210
    Proc. Natl. Acad. Sci. USA Vol. 90, pp. 4779-4781, June 1993 Colloquium Paper This paper was presented at a colloquium entitled "Physical Cosmology," organized by a committee chaired by David N. Schramm, held March 27 and 28, 1992, at the National Academy of Sciences, Irvine, CA. Challenges to the standard model of Big Bang nucleosynthesis GARY STEIGMAN Departments of Physics and Astronomy, The Ohio State University, Columbus, OH 43210 ABSTRACT Big Bang nucleosynthesis provides a unique The gap at mass-5 ensured that 4He would be the second most probe of the early evolution of the Universe and a crucial test abundant element (after hydrogen) in the Universe and that of the consistency of the standard hot Big Bang cosmological any heavier elements would be produced only in trace model. Although the primordial abundances of 2H, 3He, 4He, amounts. Since 2H and 3He (as well as 3H) are being burned and 7Li inferred from current observational data are in agree- to 4He, the higher the nucleon abundance the more rapidly ment with those predicted by Big Bang nucleosynthesis, recent are 2H and 3He burned away and the smaller will be their relic analysis has severely restricted the consistent range for the abundance. The magnitude of the nucleon abundance [as nucleon-to-photon ratio: 3.7 s 110 ' 4.0. Increased accuracy measured by the universal ratio of nucleons to (cosmic in the estimate of primordial 4He and observations of Be and background radiation) photons: 1 N/ y; 710o 101°71] is B in Pop II stars are offering new challenges to the standard crucial also to bridging the gap at mass-5 and, therefore, the model and suggest that no new light particles may be allowed mass-7 abundance is sensitive to q1.
    [Show full text]
  • Exploring the Origin of Lithium, Carbon, Strontium, and Barium with Four New Ultra Metal-Poor Stars
    EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Hansen, T., C. J. Hansen, N. Christlieb, D. Yong, M. S. Bessell, A. E. Garcia Perez, T. C. Beers, et al. “EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS.” The Astrophysical Journal 787, no. 2 (June 1, 2014): 162. © 2014 The American Astronomical Society As Published http://dx.doi.org/10.1088/0004-637X/787/2/162 Publisher IOP Publishing Version Final published version Citable link http://hdl.handle.net/1721.1/94583 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The Astrophysical Journal, 787:162 (9pp), 2014 June 1 doi:10.1088/0004-637X/787/2/162 C 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A. EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS∗ T. Hansen1,C.J.Hansen1, N. Christlieb1,D.Yong2,M.S.Bessell2,A.E.Garc´ıa Perez´ 3, T. C. Beers4,5, V. M. Placco6, A. Frebel7, J. E. Norris2, and M. Asplund2 1 Landessternwarte, ZAH, Konigstuhl¨ 12, D-69117 Heidelberg, Germany; [email protected], [email protected], [email protected] 2 Research School of Astronomy and Astrophysics, The Australian National University, Weston,
    [Show full text]
  • Protostellar Accretion in Low Mass Metal Poor Stars and the Cosmological Lithium Problem
    Astronomy & Astrophysics manuscript no. Tognelli_AccAndLithium_CorrectedLang c ESO 2020 May 1, 2020 Protostellar accretion in low mass metal poor stars and the cosmological lithium problem Emanuele Tognelli1, Pier Giorgio Prada Moroni1; 2, Scilla Degl’Innocenti1; 2, Maurizio Salaris3, and Santi Cassisi2; 4 1 Dipartimento di Fisica, Università di Pisa, Largo Bruno Pontecorvo 3, I-56127, Pisa, Italy e-mail: [email protected] 2 INFN - Sezione di Pisa, Largo Bruno Pontecorvo 3, I-56127, Pisa, Italy e-mail: [email protected] e-mail: [email protected] 3 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK 4 INAF - Osservatorio Astronomico d’Abruzzo, Via M. Maggini, I-64100, Teramo, Italy Received 18 September, 2019; accepted 24 April, 2020 ABSTRACT Context. The cosmological lithium problem, that is, the discrepancy between the lithium abundance predicted by the Big Bang nucleosynthesis and the one observed for the stars of the ’Spite plateau’, is one of the long standing problems of modern astrophysics. Recent hints for a possible solution involve lithium burning induced by protostellar mass accretion on Spite plateau stars. However, to date, most of the protostellar and pre-main sequence stellar models that take mass accretion into account have been computed at solar metallicity, and a detailed analysis on the impact of protostellar accretion on the lithium evolution in the metal-poor regime, which is relevant for stars in the Spite plateau, is completely missing. Aims. The purpose of this paper is to fill this gap, analysing, in detail, for the first time the effect of protostellar accretion on low metallicity low-mass stars with a focus on pre-main sequence lithium evolution.
    [Show full text]