bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Politics of Gender Symposium Introduction: Comparative Politics and the Logics of a Comparative Politics of Gender
Authors: Beckwith Karen
Published: March 2010

This symposium is the culmination of work that began in October 2007, when fourteen scholars from Australia, the United Kingdom, and the United States convened at Case Western Reserve University to participate in the research conferenceToward a Comparative Politics of Gender: Advancing the Discipline along Interdisciplinary Boundaries.The conference was funded by a Presidential Initiative Grant from the University and further supported by an ACES grant. Dr. Gregory Eastwood made available the Library of the Inamori Center for Ethnics and Excellence for our conference meetings. Many thanks to Linda Gilmore, Tonae Bolton-Dove, Gail Papay, Shelley White, and Sharon Skowronski for their expert administrative support. Professors Dorothy Miller (Women's Studies), Rosalind Simson (Philosophy, Law and Women's Studies), and Kelly McMann (Political Science and International Studies) served as discussants of the conference papers. To Theda Skocpol, who presented remarks at the opening dinner of the conference, and to the scholars who participated in the CPG conference and whose contributions are included in this symposium, I offer my deepest appreciation and gratitude.

What do we mean by a comparative politics of gender? How would a comparative politics of gender advance our understanding of politics generally? What would it take to develop a gendered comparative political analysis? In the essays that follow, Teri Caraway, Louise Chappell, Leslie Schwindt-Bayer, and Aili Mari Tripp elaborate their understandings of a comparative politics of gender. Five additional essays focus specifically on issues of democratization (Lisa Baldez, Georgina Waylen), political institutions and representation (Mili Caul Kittilson, Mona Lena Krook), and comparative sex equality policies (Mala Htun and Laurel Weldon). In this introductory essay, I discuss what I mean by “gender” in the context of comparative politics. Briefly enumerating the advantages of comparative politics as a subfield for a gendered analysis of political phenomena, I discuss how a comparative politics of gender can serve to advance our understanding of politics generally, and I provide an example of subfield research—the study of political violence—where gender as a metaconcept may be particularly useful. I conclude by considering what it would mean to our study of gender and of comparative politics to place gender as a central concept in comparative political research and to move to a comparative politics of gender.
Comparative Gender and Institutions: Directions for Research
Authors: Chappell Louise
Published: March 2010

A comparative politics of gender offers an opportunity to consider in detail the operation of gender within political institutions. As such, it contributes to a deeper understanding of the roles and experiences of men and women within political institutions, of the policies, laws and norms that are the outcomes of these institutions, and of the relationship between these institutions and social actors. This essay proposes a multi-directional strategy for undertaking comparative gender and institutional research that includes taking account of similarities and differences within and across states, between states and international institutions, across space as well as across time. It argues that through this research strategy it is possible to gain a more nuanced understanding of gender processes and outcomes, which is valuable to those working both inside and outside political institutions to advance a women's equality agenda.
Toward a Comparative Politics of Gender Research in which Women Matter
Authors: Tripp Aili Mari
Published: March 2010

I ask whether comparative politics of gender (CPG) can maintain its normative roots in concerns related to social justice as it moves increasingly away from its interdisciplinary moorings in gender/women's studies and gravitates toward disciplinary concerns. I call for a broad framework for CPG, examining 1) the range and relevance of the questions we ask, the utility of interdisciplinarity, and the range of methods employed; 2) the research collaborations we develop, especially outside of the US–Europe nexus; 3) the way our work is disseminated; and 4) how it engages the policy and practitioner community.
Studying Political Representation: A Comparative-Gendered Approach
Authors: Krook Mona Lena
Published: March 2010

How does a comparative politics of gender improve our understanding of political representation? I map the existing feminist literature on this topic, which asks questions like why there are so few women elected to political office, whether women in politics represent women as a group, and how the presence or absence of women in politics affects voter perceptions and opinions. I then consider how scholars—both feminist and non-feminist—might generate new insights on political representation by expanding what is thought of as a “case” and what is meant by the term “gender.” I recommend increasing the scope of comparison by (1) opening up the definition of a case to include a broader range of units and events and (2) connecting the study of a single unit to patterns generated by the study of other similar units. I suggest moving away from equating women with gender by exploring (1) relations between women and men and (2) the impact of masculinities and femininities on the conduct of political life. While developed in relation to research on representation, this approach offers broader advice for capturing the diverse and gendered nature of political dynamics observed around the world.
Third-Wave Feminism and the Defense of “Choice”
Authors: Snyder-Hall R. Claire
Published: March 2010

How should feminist theorists respond when women who claim to be feminists make “choices” that seemingly prop up patriarchy, like posing for Playboy, eroticizing male dominance, or advocating wifely submission? This article argues that the conflict between the quest for gender equality and the desire for sexual pleasure has long been a challenge for feminism. In fact, the second-wave of the American feminist movement split over issues related to sexuality. Feminists found themselves on opposite sides of a series of contentious debates about issues such as pornography, sex work, and heterosexuality, with one side seeing evidence of gender oppression and the other opportunities for sexual pleasure and empowerment. Since the mid-1990s, however, a third wave of feminism has developed that seeks to reunite the ideals of gender equality and sexual freedom. Inclusive, pluralistic, and non-judgmental, third-wave feminism respects the right of women to decide for themselves how to negotiate the often contradictory desires for both gender equality and sexual pleasure. While this approach is sometimes caricatured as uncritically endorsing whatever a woman chooses to do as feminist, this essay argues that third-wave feminism actually exhibits not a thoughtless endorsement of “choice,” but rather a deep respect for pluralism and self-determination.
Choosing Betrayal
Authors: Hirschmann Nancy J.
Published: March 2010

I respond to the foregoing essays and take up an ambivalent defense of Hirshman's argument. While agreeing with various points the contributors make, I highlight the fact that women's choices are still made under conditions of oppression that shape not only the options women have, but the desires themselves that shape their choices. Recognizing oppression as a social phenomenon allows feminists to accept a wider range of individual choices than we might think acceptable under the feminist umbrella, but it also requires a distinction between making a feminist choice and offering feminist support for choice.
Response to Lisa Wedeen's review of Capitalism and Christianity, American Style
Authors: Connolly William E.
Published: March 2010

My (outlandish) hope in Capitalism and Christianity, American Style is to help push capitalism closer to the center of political theory and political science. On my reading, a capitalist “axiomatic” binds together labor, capital, growth imperatives, and commodities. But these defining elements are also insufficient. A specific capitalist assemblage simultaneously depends upon, affects, and folds to varying degrees into its institutions other relatively autonomous force fields, including climate change, religious intensities, mutating diseases, scientific research, new political movements, novel financial instruments, compensatory hopes poured into investment and consumption, wars, and security anxieties. Such intersections combine with the intrinsic instability of markets to produce the volatility of capitalism. It, too, is an open system in a world of open systems that invade, energize, and threaten it.
Global Gender Inequality and the Empowerment of Women
Authors: Narayan Uma
Published: March 2010

Half the Sky: Turning Oppression into Opportunity for Women Worldwide is a powerful journalistic account of the oppression of women worldwide, and of the ways that some women and men have struggle against this oppression and discovered new forms of economic empowerment. The book—in its eleventh printing in less than a year, and with testimonials from the likes of Angelina Jolie and George Clooney—is also a publishing sensation. Half the Sky brings much attention to an important and timely topic, and it creatively combines narrative, analysis, and policy prescriptions, and so we invited three prominent scholars of gender inequality and development to reflect on the book's strengths and weaknesses: Ayelet Shachar, Uma Narayan, and Valentine M. Moghadam.
Global Gender Inequality and the Empowerment of Women
Authors: Shachar Ayelet
Published: March 2010

Half the Sky: Turning Oppression into Opportunity for Women Worldwide is a powerful journalistic account of the oppression of women worldwide, and of the ways that some women and men have struggle against this oppression and discovered new forms of economic empowerment. The book—in its eleventh printing in less than a year, and with testimonials from the likes of Angelina Jolie and George Clooney—is also a publishing sensation. Half the Sky brings much attention to an important and timely topic, and it creatively combines narrative, analysis, and policy prescriptions, and so we invited three prominent scholars of gender inequality and development to reflect on the book's strengths and weaknesses: Ayelet Shachar, Uma Narayan, and Valentine M. Moghadam.
Nucleosynthesis Now and Then
Authors: Woosley S. E. , Heger A. , Roberts L. , Hoffman R. D.
Published: March 2010

Today we understand, to reasonable accuracy, the origin of most of the abundant elements in the sun and similar Population I stars. Given our relatively primitive ability to model supernova explosion mechanisms, stellar mass loss, and stellar mixing, this is a remarkable achievement. This understanding is possible, in part, because supernovae are highly constrained by their spectra, light curves and the sorts of remnants they leave. This same understanding extends to the major abundances seen in primitive metal-poor stars down to [Fe/H] > −4. In particular, one finds no compelling evidence for exotic energies or unusual stellar properties. There are exceptions, however. About half of the isotopes above iron, ther-process and thep-process withA< 130, still have an uncertain origin, both in the sun and in metal-poor stars. The abundances in the hyper-iron-poor stars ([Fe/H] < −4) also require a special explanation. We suggest that they represent the operation of a first generation of massive stars that produced almost exclusively C, N, and O and black holes, a generation in which 100 M⊙were abundant, but stars over about 150 M⊙and under 30 M⊙were almost absent.
The Very First Stars: Formation and Reionization of the Universe
Authors: Bromm Volker
Published: March 2010

One of the key challenges for the next 10 years is to understand the first sources of light, the first stars and possibly accreting black holes. Their formation ended the cosmic dark ages at redshifts z ≃ 20 − 30, and signaled the transition from the simple initial state of the universe to one of ever increasing complexity. We here review recent progress in understanding the formation process of the first stars with numerical simulations, starting with cosmological initial conditions and modelling the detailed physics of accretion. Once formed, the first stars exerted crucial feedback on the primordial intergalactic medium, due to their input of radiation and of heavy chemical elements in the wake of supernova explosions. The current theoretical model posits that the first stars were predominantly very massive, typically ~100 M⊙. Our predictions will be tested with upcoming near-infrared observatories, such as the James Webb Space Telecope, in the decade ahead.
The Nucleosynthetic Imprint of 15 - 40 M⊙ Primordial Supernovae on Metal-Poor Stars
Authors: Whalen Daniel J. , Joggerst Candace C.
Published: March 2010

The first stars are key to the formation of primeval galaxies, early cosmological reionization, and the assembly of supermassive black holes. Although Population III stars lie beyond the reach of direct observation, their chemical imprint on long-lived second generation stars may yield indirect measures of their masses. While numerical models of primordial SN nucleosynthetic yields have steadily improved in recent years, they have not accounted for the chemical abundances of ancient metal-poor stars in the Galactic halo. We present new two-dimensional models of 15 - 40 M⊙ primordial SNe that capture the effect of progenitor rotation, mass, metallicity, and explosion energy on elemental yields. Rotation dramatically alter the structure of zero-metallicity stars, expanding them to much larger radii. This promotes mixing between elemental shells by the SN shock and fallback onto the central remnant, both of which govern which elements escape the star. We find that a Salpeter IMF average of our yields for Z=0 models with explosion energies of 2.4 × 1051 ergs or less is in good agreement with the abundances measured in extremely metal-poor stars. Because these stars were likely enriched by early SNe from a well-defined IMF, our models indicate that the bulk of the metals in the early universe were synthesized by low-mass primordial stars.
Constraints on the Nature of the s- and r-processes
Authors: Sneden Christopher , Cowan John J. , Gallino Roberto
Published: March 2010

Neutron-capture (Z > 30) elements are detected in many very metal-poor halo stars, and so they must have been manufactured by some of the earliest element donors in our Galaxy's history. The bulk amounts of neutron-capture elements with respect to the iron group vary by several orders of magnitude from star to star at low metallicities. Additionally, abundance distributions among these elements are often strikingly different from that of the solar system. Some stars exhibit abundances that must have been made purely in “rapid” neutron-capture events (the r-process), some in “slow” events (the s-process), and some have hybrid mixes. Here we summarize the major observed categories of the neutron-capture abundances in metal-poor stars, and discuss their implications for early Galactic nucleosynthesis.
The slow-neutron capture process in low-metallicity asymptotic giant branch stars
Authors: Karakas Amanda I. , Lugaro Maria , Campbell Simon W.
Published: March 2010

Elements heavier than iron are produced in asymptotic giant branch (AGB) stars via the slow neutron capture process (s process). Recent observations of s-process-enriched Carbon Enhanced Metal-Poor (CEMP) stars have provided an unprecedented wealth of observational constraints on the operation of the s-process in low-metallicity AGB stars. We present new preliminary full network calculations of low-metallicity AGB stars, including a comparison to the composition of a few s-process rich CEMP stars. We also discuss the possibility of using halo planetary nebulae as further probes of low-metallicity AGB nucleosynthesis.
Enrichment of Thorium (Th) and Lead (Pb) in the early Galaxy
Authors: Aoki Wako , Honda Satoshi
Published: March 2010

We have been determining abundances of Th, Pb and other neutron-capture elements in metal-deficient cool giant stars to constrain the enrichment of heavy elements by the r- and s-processes. Our current sample covers the metallicity range between [Fe/H] = −2.5 and −1.0. (1) The abundance ratios of Pb/Fe and Pb/Eu of most of our stars are approximately constant, and no increase of these ratios with increasing metallicity is found. This result suggests that the Pb abundances of our sample are determined by the r-process with no or little contribution of the s-process. (2) The Th/Eu abundance ratios of our sample show no significant scatter, and the average is lower by 0.2 dex in the logarithmic scale than the solar-system value. This result indicates that the actinides production by the r-process does not show large dispersion, even though r-process models suggest high sensitivity of the actinides production to the nucleosynthesis environment.
The impact of metallicity on the formation of pre-collapsing minihalos
Authors: Aykutalp Aycin , Spaans Marco
Published: March 2010

In this study we consider the pre-enrichment of minihalos, and study the impact of metallicity on pre-collapsing minihalos by using the cosmological, N-body simulation code Enzo. The metallicities that we consider are assumed to be the result of pre-enrichment by earlier star formation. In the simulations of 10−3 and 10−1 Z⊙ we see a big difference for the collapse of the minihalo. In the high metallicity case the minihalo is more compact compared to the low metallicity case and we reach higher densities due to the efficient cooling. Also in the high metallicity case the gas cools down to lower temperatures and we see cold, dense gas which indicates a multi-phase ISM. This leads us to think that there is a transition region between metallicities of 10−3 and 10−1 Z⊙ which lowers the mass scale of the next generation of stars. Furthermore, because the gas cools more efficiently in the high metallicity case there is less pressure support against gravity and therefore we see higher velocities.
The importance of initial conditions and metallicity for the fragmentation of protogalactic gas
Authors: Jappsen Anne-Katharina , Glover Simon C. O. , Mac Low Mordecai-Mark , Klessen Ralf S.
Published: March 2010

The formation of the first stars out of metal-free gas appears to result in stars at least an order of magnitude more massive than in the present-day case. We here consider what controls the transition from a primordial to a modern initial mass function. We study the influence of low levels of metal enrichment and different initial conditions on the cooling and collapse of initially ionized gas in small protogalactic halos using three-dimensional, smoothed particle hydrodynamics simulations. We argue that fragmentation at moderate density depends on the initial conditions for star formation more than on the metal abundances present.
Silver Stars
Authors: Hansen Camilla Juul , Primas Francesca
Published: March 2010

The rapid neutron-capture process (r-process), which produces some of the heaviest elements, is not well understood. Obtaining accurate abundances of these heavy elements (Z > 38) is important, both in the context of the chemical evolution of the Galaxy and for understanding the site(s) and process(es) of formation of those elements. We have determined elemental abundances for several r-process elements, notably silver, from high resolution VLT/UVES spectra. Silver was chosen because it is predominantly a light r-process element (38 < Z < 50), and little is known about its formation and evolution in the Galaxy. Here, we present our preliminary results.
Gamma-ray bursts in the early Universe
Authors: Mészáros Attila , Řípa Jakub , Huja David
Published: March 2010

The long gamma-ray bursts are at high redshifts, and they trace the star-formation rate. Hence, they may well serve as milestones in the early Universe.
The first galactic stars and chemical enrichment in the halo
Authors: Bonifacio Piercarlo
Published: March 2010

The cosmic microwave background and the cosmic expansion can be interpreted as evidence that the Universe underwent an extremely hot and dense phase about 14 Gyr ago. The nucleosynthesis computations tell us that the Universe emerged from this state with a very simple chemical composition: H, 2H, 3He, 4He, and traces of 7Li. All other nuclei where synthesised at later times. Our stellar evolution models tell us that, if a low-mass star with this composition had been created (a “zero-metal” star) at that time, it would still be shining on the Main Sequence today. Over the last 40 years there have been many efforts to detect such primordial stars but none has so-far been found. The lowest metallicity stars known have a metal content, Z, which is of the order of 10−4Z⊙. These are also the lowest metallicity objects known in the Universe. This seems to support the theories of star formation which predict that only high mass stars could form with a primordial composition and require a minimum metallicity to allow the formation of low-mass stars. Yet, since absence of evidence is not evidence of absence, we cannot exclude the existence of such low-mass zero-metal stars, at present. If we have not found the first Galactic stars, as a by product of our searches we have found their direct descendants, stars of extremely low metallicity (Z ≤ 10−3Z⊙). The chemical composition of such stars contains indirect information on the nature of the stars responsible for the nucleosynthesis of the metals. Such a fossil record allows us a glimpse of the Galaxy at a look-back time equivalent to redshift z = 10, or larger. The last ten years have been full of exciting discoveries in this field, which I will try to review in this contribution.
An overall picture of EMP stars using the stellar abundances for galactic archaeology (SAGA) database
Authors: Suda Takuma , Yamada Shimako , Katsuta Yutaka , Ishizuka Chikako , Komiya Yutaka , Nishimura Takanori , Aoki Wako , Fujimoto Masayuki Y.
Published: March 2010

We explore the general characteristics of extremely metal-poor (EMP) stars in the Galaxy using the Stellar Abundances for Galactic Archaeology (SAGA) database (Suda et al. 2008, PASJ, 60, 1159). The overall trend of EMP stars suggests that there are at least two types of extra mixing to change the surface abundances of EMP stars. One is to deplete lithium abundance during the early phase of giant branch and another is to decrease C/N ratio by one order of magnitude during the red giant branch or AGB phase. On the other hand, these mixing processes are different from those suggested in the Galactic globular clusters because of the different relations between O, Na, Mg, and Al abundances.
HST-STIS abundances in the uranium-rich very metal-poor star CS 31082-001
Authors: Barbuy B. , Spite M. , Hill V. , Primas F. , Plez B. , Cayrel R. , Sneden C. , Spite F. , Beers T. C. , Andersen J. , Nordström B. , Bonifacio P. , François P. , Molaro P. , Siqueira-Mello C.
Published: March 2010

The abundance derivation of heavy r-elements may provide a better understanding of the r-process, and the determination of several reference r-elements should allow a better determination of the star's age. The spatial ultraviolet (UV) region presents a large number of lines of heavy elements, and in some cases such as Bi, Pt, Au, detectable lines are only available in the UV. The extreme “r-process star” CS 31082-001 ([Fe/H] = −2.9) was observed in the spatial UV in order to determine abundances of the heavy elements, using STIS on board HST.
Near-IR Spectroscopy of CEMP Stars with SOAR/OSIRIS
Authors: Kennedy Catherine R. , Sivarani Thirupathi , Beers Timothy C. , Rossi Silvia , Placco Vinicius M. , Johnson J. , Masseron T.
Published: March 2010

We report on medium-resolution near-IR spectroscopy of a sample of over 60 Carbon-Enhanced Metal-Poor (CEMP) stars observed with SOAR/OSIRIS, selected from the HK survey of Beers and colleagues and the Hamburg/ESO Survey of Christlieb and colleagues. Oxygen abundances from the molecular CO lines as well as rough estimates of 12C/13C ratios are estimated from the near-IR spectra of these stars. Near-IR model spectra with varying oxygen abundances, in combination with previously determined parameters from optical spectra are used for the estimation of abundances for this sample. As both oxygen abundances and 12C/13C ratios are tracers of nucleosynthesis, we hope to gain information about Galactic nucleosynthesis through the analysis of this sample.
A Search for Unrecognized Carbon-Enhanced Metal-Poor Stars
Authors: Placco Vinicius M. , Kennedy Catherine R. , Rossi Silvia , Beers Timothy C. , Christlieb Norbert , Sivarani Thirupathi
Published: March 2010

We have developed a new procedure to search for Carbon-Enhanced Metal-Poor (CEMP) stars from the Hamburg/ESO (HES) prism-survey plates. This method uses an extended line index for the CH G-band, which we demonstrate to have superior behavior when compared to the narrower G-band index formerly employed for these spectra.

A first subsample, biased towards brighter stars (B<15.5), has been extracted from the scanned HES plates. After visual inspection (to eliminate spectra compromised by plate defects, overlapping spectra, etc., and to carry out rough spectral classifications), a list of 669 previously unidentified candidate CEMP stars was compiled. Follow-up spectroscopy for a pilot sample of 132 candidates was obtained on the SOAR 4.1m telescope. Our results show that most of the stars observed lie in the targetted metallicity range, and possess prominent carbon absorption features at 4300Å. The success rate for the identification of new CEMP stars is ~50% for [Fe/H]< −2.0. For stars with [Fe/H]< −2.5, the ratio increases to 100%.
A view of the Galactic halo using beryllium as a time scale
Authors: Smiljanic Rodolfo , Pasquini L. , Bonifacio P. , Galli D. , Barbuy B. , Gratton R. , Randich S.
Published: March 2010

Beryllium stellar abundances were suggested to be a good tracer of time in the early Galaxy. In an investigation of its use as a cosmochronometer, using a large sample of local halo and thick-disk dwarfs, evidence was found that in a log(Be/H) vs. [α/Fe] diagram the halo stars separate into two components. One is consistent with predictions of evolutionary models while the other is chemically indistinguishable from the thick-disk stars. This is interpreted as a difference in the star formation history of the two components and suggests that the local halo is not a single uniform population where a clear age-metallicity relation can be defined.
The Cosmic Chemical Evolution as seen by the Brightest Events in the Universe
Authors: Savaglio Sandra
Published: March 2010

Gamma-ray bursts (GRBs) are the brightest events in the universe. They have been used in the last five years to study the cosmic chemical evolution, from the local universe to the first stars. The sample size is still relatively small when compared to field galaxy surveys. However, GRBs show a universe that is surprising. At z > 2, the cold interstellar medium in galaxies is chemically evolved, with a mean metallicity of about 1/10 solar. At lower redshift (z < 1), metallicities of the ionized gas are relatively low, on average 1/6 solar. Not only is there no evidence of redshift evolution in the interval 0 < z < 6.3, but also the dispersion in the ~30 objects is large. This suggests that the metallicity of host galaxies is not the physical quantity triggering GRB events. From the investigation of other galaxy parameters, it emerges that active star-formation might be a stronger requirement to produce a GRB. Several recent striking results strongly support the idea that GRB studies open a new view on our understanding of galaxy formation and evolution, back to the very primordial universe at z ~ 8.
Possibility of measuring the amount of intergalactic metals with 14N VII HFS line
Authors: Docenko Dmitrijs , Sunyaev Rashid A.
Published: March 2010

We discuss possibility of observations of the warm-hot intergalactic medium using the hyperfine structure line of highly charged nitrogen ion 14N VII (rest wavelength λ = 5.652 mm). Observations of this line will allow to separate bulk and turbulent motions in the observed target and will broaden the information about the gas ionization state, chemical and isotopic composition.

Wavelength of this line is well-suited for ground-based observation of objects at z ≈ 0.15 − 0.6 when it is redshifted to the widely-used 6.5 − 9 mm spectral band, and, for example, for z ≥ 1.3, when the line can be observed in 1.3 cm band and at lower frequencies.
Quasar Metal Abundances & Host Galaxy Evolution
Authors: Hamann Fred , Simon Leah E.
Published: March 2010

High-redshift quasars provide a unique glimpse into the early evolution of massive galaxies. The physical processes that trigger major bursts of star formation in quasar host galaxies (mergers and interactions) probably also funnel gas into the central regions to grow the super-massive black holes (SMBHs) and ignite the luminous quasar phenomenon. The globally dense environments where this occurs were probably also among the first to collapse and manufacture stars in significant numbers after the big bang. Measurements of the elemental abundances near quasars place important constraints on the nature, timing and extent of this star formation. A variety of studies using independent emission and absorption line diagnostics have shown that quasar environments have gas-phase metallicities that are typically a few times solar at all observed redshifts. These results are consistent with galaxy evolution scenarios in which large amounts of star formation (e.g., in the central regions) precede the visibly bright quasar phase. An observed trend for higher metallicities in more luminmous quasars (powered by more massive SMBHs) is probably tied to the well-known mass–metallicity relation among ordinary galaxies. This correlation and the absence of a trend with redshift indicate that mass is a more important parameter in the evolution than the time elapsed since the big bang.
Lookback time evolution of metals: discarding the closed box model
Authors: Rodrigues M. , Hammer F. , Flores H. , Puech M.
Published: March 2010

We have gathered a representative sample of 88 intermediate mass galaxies at z~0.6 and have provided robust estimates of their gas phase metallicity based on the strong line method R23. We have found that these galaxies have undergone a strong evolution of their metal content during the last 8 Gyrs. We confirmed the shift about ~0.3dex to lower abundance of the M-Z relation at z~0.6 found by Liang et al. 2006. This result shows that the evolution of the gas phase is still active down to z=0.4 and that the close box model is not a valid scenario for local spiral progenitors.
Tracing Metallicity in High Redshift Quasars
Authors: Simon Leah E. , Hamann Fred
Published: March 2010

We present two ongoing studies of gas phase abundances around high redshift quasars. First, we examine broad emission line (BEL) metallicities for 29 quasars with 2.3 < z < 4.6 and far-infrared (far-IR) luminosities (LFIR) from 1013.4 to ≤ 1012.2 L⊙, corresponding to star formation rates (SFRs) of 6740 to ≤ 1360 M⊙ yr−1. Quasar samples sorted by LFIR might represent an evolutionary sequence if SFRs in quasar hosts generally diminish across quasar lifetimes. We create three composite spectra from rest-frame ultra-violet Sloan Digital Sky Survey spectra with increasing far-IR luminosity. We measure the N V(λ1240)/C IV(λ1550) and Si IV(λ1397)+O IV](λ1402)/C IV(λ1550) emission line flux ratios for each composite and find uniformly high (~5-10 times solar) metallicities for the three composites, and no evidence for changes in metal enrichment with changes in ongoing SFR. Second, we present preliminary results from the largest ever survey of high resolution associated absorption line (AAL) region metallicities and physical properties in a sample of high redshift (z > 3) quasars. This includes five quasars with previously known AALs at z > 4 and two well measured z ~3 quasars with unusually rich absorption spectra. We determine well-constrained metallicities of about twice solar for five AAL systems. We find a range of lower limits for AAL metallicities in the z > 4 quasars from 1/100ths solar to 3 times solar. Overall, these results for typically super-solar gas-phase metallicities near quasars are consistent with evolutionary schemes where the major episodes of star formation in the host galaxies occur before the visibly luminous quasar phase. High SFRs (comparable to ULIRGs) in the host galaxies are not clearly linked to younger or chemically less mature quasar environments.
Fe I/Fe II ionization equilibrium in cool stars: NLTE versus LTE
Authors: Mashonkina Lyudmila , Gehren Thomas , Shi Jianrong , Korn Andreas , Grupp Frank
Published: March 2010

Non-local thermodynamic equilibrium (NLTE) line formation for neutral and singly-ionized iron is considered through a range of stellar parameters characteristic of cool stars. A comprehensive model atom for Fe I and Fe II is presented. Our NLTE calculations support the earlier conclusions that the statistical equilibrium (SE) of Fe I shows an underpopulation of Fe I terms. However, the inclusion of the predicted high-excitation levels of Fe I in our model atom leads to a substantial decrease in the departures from LTE. As a test and first application of the Fe I/II model atom, iron abundances are determined for the Sun and four selected stars with well determined stellar parameters and high-quality observed spectra. Within the error bars, lines of Fe I and Fe II give consistent abundances for the Sun and two metal-poor stars when inelastic collisions with hydrogen atoms are taken into account in the SE calculations. For the close-to-solar metallicity stars Procyon and β Vir, the difference (Fe II - Fe I) is about 0.1 dex independent of the line formation model, either NLTE or LTE. We evaluate the influence of departures from LTE on Fe abundance and surface gravity determination for cool stars.
Problems in abundance determination from UV spectra of hot supergiants
Authors: Deković M. Sarta , Kotnik-Karuza D. , Jurkić T. , Prester D. Dominis
Published: March 2010

We present measurements of equivalent widths of the UV, presumably photospheric lines: C III 1247 Å, N III 1748 Å, N III 1752 Å, N IV 1718 Å and He II 1640 Å in high-resolution IUE spectra of 24 galactic OB supergiants. Equivalent widths measured from the observed spectra have been compared with their counterparts in the Tlusty NLTE synthetic spectra. We discuss possibilities of static plan-parallel model to reproduce observed UV spectra of hot massive stars and possible reasons why observations differ from the model so much.
The Determination of the Abundances of the Fe Group Elements in Early B Stars from High Resolution FUV Spectra
Authors: Peters Geraldine J. , Adelman Saul J. , Hubeny Ivan , Lanz Thierry
Published: March 2010

We present selected results from an investigation that is currently underway to determine the abundances of the Fe group elements in early B stars and assess the extent to which contemporary NLTE and LTE models represent their atmospheres. High resolution UV and optical spectra of B stars that display ultrasharp lines are compared with computations from TLUSTY/SYNSPEC and SYNTHE. Some results from our analysis of the abundance standard ι Her (B3V) are presented here.
Accurate Fundamental Stellar Parameters
Authors: Bruntt Hans
Published: March 2010

We combine results from interferometry, asteroseismology and spectroscopic analyses to determine accurate fundamental parameters (mass, radius and effective temperature) of 10 bright solar-type stars covering the H-R diagram from spectral type F5 to K1. Using “direct” techniques that are only weakly model-dependent we determine the mass, radius and effective temperature. We demonstrate that model-dependent or “indirect” methods can be reliably used even for relatively faint single stars for which direct methods are not applicable. This is important for the characterization of the targets of the CoRoT and Kepler space missions.
Abundance patterns and the chemical enrichment of nearby dwarf galaxies
Authors: Hill Vanessa
Published: March 2010

As the least massive galaxies we know, dwarf spheroidal galaxies (dSph) allow to probe chemical enrichement on the smallest scales, and perhaps in its simplest expression. Particularly interesting are the issues concerning the efficency with which metals are retained or lost in these shallow potential wells (supernovae feedback), and the effect of this on star formation itself. Another fundamental issue concerns the earliest epochs of star formation: are first stars formed in similar ways and proportions in all halos ? Finally, as the smallest galaxies know, dSph have been suggested to be the surviving cousins of galaxy building blocs that (in λ-CDM) assemble to make larger galaxies. This parenthood would not necessarily hold at all late times, when survivors have lived their own differentiated life, but is expected at least at the earliest epochs.

I review here the chemical abundances of individual stars in the nearest dwarf spheroidal galaxies, that have become available in increasing numbers (sample size and galaxies probed) in the last decade. Special emphasis is given to: a) recent results obtain with FLAMES on VLT, highlighting the power of detailed chemical abundance patterns of large samples of stars to unravel the various evolutionnary paths followed by dSph; b) the oldest and most metal-poor populations in dSph.
Complexity in small-scale dwarf spheroidal galaxies
Authors: Koch Andreas , Adén Daniel , Grebel Eva K. , Feltzing Sofia
Published: March 2010

Our knowledge about the chemical evolution of the more luminous dwarf spheroidal (dSph) galaxies is constantly growing. However, little is known about the enrichment of the ultrafaint systems recently discovered in large numbers in large Sky Surveys. Low-resolution spectroscopy and photometric data indicate that these galaxies are predominantly metal-poor. On the other hand, the most recent high-resolution abundance analyses indicate that some of these galaxies experienced highly inhomogenous chemical enrichment, where star formation proceeds locally on the smallest scales. Furthermore, these galaxy-contenders appear to contain very metal-poor stars with [Fe/H]< −3 dex and could be the sites of the first stars. Here, we consider the presently available chemical abundance information of the (ultra-) faint Milky Way satellite dSphs. In this context, some of the most peculiar element and inhomogeneous enrichment patterns will be discussed and related to the question of to what extent the faintest dSph candidates and outer halo globular clusters could have contributed to the metal-poor Galactic halo.
Extremely metal-poor stars in dwarf galaxies
Authors: Frebel Anna , Simon Joshua D. , Kirby Evan , Geha Marla , Willman Beth
Published: March 2010

We present Keck/HIRES spectra of six metal-poor stars in two of the ultra-faint dwarf galaxies orbiting the Milky Way, Ursa Major II and Coma Berenices, and a Magellan/MIKE spectrum of a star in the classical dwarf spheroidal galaxy (dSph) Sculptor. Our data include the first high-resolution spectroscopic observations of extremely metal-poor stars ([Fe/H] < −3.0) not belonging to the Milky Way (MW) stellar halo field population. We obtain abundance measurements and upper limits for up to 26 elements between carbon and europium. The stars span a range of −3.8 < [Fe/H] < −2.3, with the ultra-faints having large spreads in Fe. A comparison with MW halo stars of similar metallicity reveals substantial agreement between the abundance patterns of the ultra-faint dwarf galaxies and Sculptor and the MW halo for the light, α and iron-peak elements (C to Zn). This agreement contrasts with the results of earlier studies of more metal-rich stars (−2.5 ≲[Fe/H]≲ −1.0) in more luminous dwarfs, which found significant abundance discrepancies with respect to the MW halo data. The abundances of neutron-capture elements (Sr to Eu) in all three galaxies are extremely low, consistent with the most metal-poor halo stars, but not with the typical halo abundance pattern at [Fe/H]≳ −3.0. Our results are broadly consistent with a galaxy formation model which predicts that massive dwarf galaxies are the source of the metal-rich component ([Fe/H]≳ −2.5) of the MW inner halo, but we propose that dwarf galaxies similar to the dSphs are the primary contributors to the metal-poor end of the metallicity distribution of the MW outer halo.
Feh-Duf: very high-velocity low-metallicity star with peculiar chemical abundance
Authors: Drake Natalia A. , Pereira Claudio B.
Published: March 2010

We present the results of a study of the very high velocity (υrad = +448.0 ± 1.0 kms−1) low-metallicity ([Fe/H] = −1.93) star Feh-Duf ((Fehrenbach & Duflot 1981) showing peculiar chemical abundance. Using high-resolution spectrum, we showed that this star has enhanced carbon and heavy s-process element abundance ([C/Fe] = +0.58, [hs/Fe] = +0.88 dex) while the [Y/Fe] = −0.07 dex). The carbon isotopic ratio is low (12C/13C=8). We found that oxygen abundance is reduced ([O/Fe] = +0.10 dex) as compared with Galactic field stars of a similar metallicity. The evolution state of this star and its possible extragalactic origin are discussed.
Chemical evolution models for local group dwarf spheroidal galaxies: the evolution of Fe-peak elements
Authors: Lanfranchi Gustavo A. , Matteucci Francesca , Cescutti Gabriele
Published: March 2010

The evolution of Fe-peak elements of several Local Group Dwarf Spheroidal Galaxies are discussed based on the comparison between a chemical evolution model and obsevations. In our scenario, the evolution of these galaxies are mainly controlled by a low star formation efficiency coupled with very intense galactic winds. The low star formation rate gives rise to the observed low metallicities and to [alpha/Fe] and [s/Fe] ratios below solar, whereas the intense galactic winds are responsible for the sharp decrease observed in several abundance ratios. The shape of the stellar metallicity distributions are defined by both parameters and the observed data cannot be reproduced without evoking galactic winds. The same scenario applied to a standard model fits very well several Fe-peak elements, with different nucleosynthesis prescriptions for each set of elements.
The Effect of the Corotation on the Radial Gradient of Metallicity of Spiral Galaxies
Authors: Scarano Sergio , Lépine Jacques R. D.
Published: March 2010

The corotation radius in a spiral galaxy is the place where the spiral pattern speed has the same velocity of the rotation curve. By compiling results coming from the literature for 20 spiral galaxies we verified a strong correlation between the radius of the minima or inflections of the metallicity distribution and the corotation radius.
Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
Authors: Carollo D. , Beers T. C. , Chiba M. , Norris J. E. , Freeman K. C. , Lee Y. S.
Published: March 2010

The structure and kinematics of the recognized stellar components of the Milky Way are explored, based on well-determined atmospheric parameters and kinematic quantities for 32360 “calibration stars” from the Sloan Digital Sky Survey (SDSS) and its first extension, (SDSS-II), which included the sub-survey SEGUE: Sloan Extension for Galactic Understanding and Exploration. Full space motions for a sub-sample of 16920 stars, exploring a local volume within 4 kpc of the Sun, are used to derive velocity ellipsoids for the inner- and outer-halo components of the Galaxy, as well as for the canonical thick-disk and proposed metal-weak thick-disk populations. This new sample of calibration stars represents an increase of 60% relative to the numbers used in a previous analysis. A Maximum Likelihood analysis of a local sub-sample of 16920 calibration stars has been developed in order to extract kinematic information for the major Galactic components (thick disk, inner halo, and outer halo), as well as for the elusive metal-weak thick disk (MWTD). We measure velocity ellipsoids for the thick disk, the MWTD, the inner halo, and the outer halo, demonstrate that the MWTD may be a component that is kinematically and chemically independent of the canonical thick disk (and put limits on the metallicity range of the MWTD), and derive the inferred spatial density profiles of the inner/outer halo components. We also present evidence for tilts in the velocity ellipsoids for stars in our sample as a function of height above the plane, for several ranges in metallicity, and confirm the shift of the observed metallicity distribution function (MDF) from the inner-halo to the outer-halo dominated sample.
CNO abundances in the Galactic bulge
Authors: Ryde Nils A. E.
Published: March 2010

The carbon, nitrogen, and oxygen abundances and trends in the bulge are discussed in the context of our recent analysis of these elements in an on-going project based on near-IR spectra (Rydeet al. 2009). We obtained these using the CRIRES spectrometer on the VLT. The formation and evolution of the Milky Way bulge can be constrained by studying elemental abundances of bulge stars. Due to the large and variable visual extinction in the line-of-sight towards the bulge, an analysis in the near-IR is preferred.
Planetary nebulae and star formation history in the Galactic disk and bulge
Authors: Milanova Yulia , Kholtygin Alexander
Published: March 2010

The modern observations of the planetary nebulae (PNe) were used to create a new catalogue of He, C, N, O, Ne, S and some other element abundances for more than 300 Galactic and extragalactic PNe. This catalogue was a start point for studying the star formation history in the Galactic disk. We have found that He, C, N and O abundances in the thin disk PNe are very close to those in bulge PNe. We also established that the abundances of the same elements in the PNe belonging the halo of the Milky Way and the Magellanic Clouds are similar. We have estimated the mean ages of the progenitors of PNe in the thin and thick disks and in the bulge. The evidences in the favor of the suggestion that the formation of the intermediate-mass star began in bulge and only then continued in the thin disk were found.
Chemo-dynamical simulations of galaxies
Authors: Kobayashi Chiaki
Published: March 2010

We simulate the formation and evolution of galaxies with a self-consistent 3D hydrodynamical model including star formation, supernova feedback, and chemical enrichment. Hypernova feedback plays an essential role not only in solving the [Zn/Fe] problem, but also reproducing the cosmic star formation rate history and the mass-metallicity relations. In the Milky-Way type galaxy, the star formation history, and thus the kinematics and chemical abundances are different in bulge, disk, and thick disk.
Metal-poor globular clusters of the galactic bulge
Authors: Barbuy B. , Ortolani S. , Zoccali M. , Hill V. , Minniti D. , Bica E. , Renzini A. , Gómez A.
Published: March 2010

Very few abundance analyses of individual stars in metal-poor globular clusters in the galactic bulge are available. The main purpose of this study is to derive abundances in individual stars of such clusters, in order to establish their abundance pattern, trying to characterize the oldest bulge stellar populations.