Heavy element abundances in a new sample of low-metallicity blue compact galaxies

1995 ◽  
Vol 445 ◽  
pp. 108 ◽  
Author(s):  
Trinh X. Thuan ◽  
Yuri I. Izotov ◽  
Valentin A. Lipovetsky
Keyword(s):  
Heavy Element ◽  
Element Abundances ◽  
Low Metallicity ◽  
Compact Galaxies

Heavy‐Element Abundances in Blue Compact Galaxies

1999 ◽  
Vol 511 (2) ◽  
pp. 639-659 ◽  
Author(s):  
Yuri I. Izotov ◽  
Trinh X. Thuan
Keyword(s):  
Heavy Element ◽  
Element Abundances ◽  
Compact Galaxies

scholarly journals Heavy Element Abundances in Planetary Nebulae: A Theorist's Perspective

2010 ◽  
Vol 27 (2) ◽  
pp. 227-231 ◽  
Author(s):  
Amanda I. Karakas ◽  
Maria Lugaro
Keyword(s):  
Heavy Element ◽  
Asymptotic Giant Branch ◽  
Type I ◽  
Intermediate Mass ◽  
Element Abundances ◽  
Exciting Opportunity ◽  
Solar Metallicity ◽  
Low Metallicity ◽  
Low Mass

AbstractThe 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 calculations on AGB models of a large range of mass and metallicity to obtain predictions for the production of neutron-capture elements up to the first s-process peak at strontium. We find that solar metallicity intermediate-mass AGB models provide a reasonable match to the heavy element composition of Type I PNe. Likewise, many of the Se and Kr enriched PNe are well fitted by lower mass models with solar or close-to-solar metallicities. However, those objects most enriched in Krand those PN with sub-solar Se/O ratios are difficult to explain with AGB-nucleosynthesis models. Furthermore, we compute s-process abundance predictions for low-mass AGB models of very low metallicity ([Fe/H]≈−2.3) using both scaled solar and an α-enhanced initial composition. For these models, O is dredged to the surface, which means that abundance ratios measured relative to this element (e.g. X/O) do not provide a reliable measure of initial abundance ratios, or of production within the star owing to internal nucleosynthesis.

Distribution of R- and S-Process Elements in the Galactic Halo

1988 ◽  
Vol 132 ◽  
pp. 501-506
Author(s):  
C. Sneden ◽  
C. A. Pilachowski ◽  
K. K. Gilroy ◽  
J. J. Cowan
Keyword(s):  
Heavy Element ◽  
Galactic Halo ◽  
Low Noise ◽  
Heavy Elements ◽  
Process Synthesis ◽  
Element Abundances ◽  
Halo Stars ◽  
Abundance Patterns ◽  
R Process ◽  
Process Elements

Current observational results for the abundances of the very heavy elements (Z>30) in Population II halo stars are reviewed. New high resolution, low noise spectra of many of these extremely metal-poor stars reveal general consistency in their overall abundance patterns. Below Galactic metallicities of [Fe/H] Ã −2, all of the very heavy elements were manufactured almost exclusively in r-process synthesis events. However, there is considerable star-to-star scatter in the overall level of very heavy element abundances, indicating the influence of local supernovas on element production in the very early, unmixed Galactic halo. The s-process appears to contribute substantially to stellar abundances only in stars more metal-rich than [Fe/H] Ã −2.

Tracing the Origins of the Ice Giants through Noble Gas Isotopic Composition

2021 ◽  
Author(s):  
Kathleen Mandt ◽  
Olivier Mousis ◽  
Jonathan Lunine ◽  
Bernard Marty ◽  
Thomas Smith ◽  
...  
Keyword(s):  
Solar System ◽  
Isotopic Composition ◽  
Heavy Element ◽  
Noble Gas ◽  
Giant Planet ◽  
Isotope Ratios ◽  
Building Blocks ◽  
Giant Planets ◽  
Element Abundances ◽  
Current State

<p>The current composition of giant planet atmospheres provides information on how such planets formed, and on the origin of the solid building blocks that contributed to their formation. Noble gas abundances and their isotope ratios are among the most valuable pieces of evidence for tracing the origin of the materials from which the giant planets formed. In this review we first outline the current state of knowledge for heavy element abundances in the giant planets and explain what is currently understood about the reservoirs of icy building blocks that could have contributed to the formation of the Ice Giants. We then outline how noble gas isotope ratios have provided details on the original sources of noble gases in various materials throughout the solar system. We follow this with a discussion on how noble gases are trapped in ice and rock that later became the building blocks for the giant planets and how the heavy element abundances could have been locally enriched in the protosolar nebula. We then provide a review of the current state of knowledge of noble gas abundances and isotope ratios in various solar system reservoirs, and discuss measurements needed to understand the origin of the ice giants. Finally, we outline how formation and interior evolution will influence the noble gas abundances and isotope ratios observed in the ice giants today. Measurements that a future atmospheric probe will need to make include (1) the <sup>3</sup>He/<sup>4</sup>He isotope ratio to help constrain the protosolar D/H and <sup>3</sup>He/<sup>4</sup>He; (2) the <sup>20</sup>Ne/<sup>22</sup>Ne and <sup>21</sup>Ne/<sup>22</sup>Ne to separate primordial noble gas reservoirs similar to the approach used in studying meteorites; (3) the Kr/Ar and Xe/Ar to determine if the building blocks were Jupiter-like or similar to 67P/C-G and Chondrites; (4) the krypton isotope ratios for the first giant planet observations of these isotopes; and (5) the xenon isotopes for comparison with the wide range of values represented by solar system reservoirs.</p><p>Mandt, K. E., Mousis, O., Lunine, J., Marty, B., Smith, T., Luspay-Kuti, A., & Aguichine, A. (2020). Tracing the origins of the ice giants through noble gas isotopic composition. Space Science Reviews, 216(5), 1-37.</p>

scholarly journals CONSTRAINTS ON THE FORMATION OF THE GALACTIC BULGE FROM Na, Al, AND HEAVY-ELEMENT ABUNDANCES IN PLAUT's FIELD

2012 ◽  
Vol 749 (2) ◽  
pp. 175 ◽  
Author(s):  
Christian I. Johnson ◽  
R. Michael Rich ◽  
Chiaki Kobayashi ◽  
Jon P. Fulbright
Keyword(s):  
Heavy Element ◽  
Galactic Bulge ◽  
Element Abundances

scholarly journals A Spectroscopic Survey in the EUV of the “Coolest” Hot DA Stars

1996 ◽  
Vol 152 ◽  
pp. 217-222
Author(s):  
Jean Dupuis ◽  
Stéphane Vennes
Keyword(s):  
Effective Temperature ◽  
White Dwarfs ◽  
Heavy Element ◽  
Extreme Ultraviolet ◽  
Diffusion Theory ◽  
Hydrogen Atmosphere ◽  
Element Abundance ◽  
Pure Hydrogen ◽  
Element Abundances ◽  
The One

We present an analysis of the extreme ultraviolet (EUV) spectroscopy of a sample of 10 DA white dwarfs observed by the Extreme Ultraviolet Explorer (EUVE). We have selected white dwarfs cooler than about 50,000 K and with presumably low heavy element abundances. The goal of this study is to determine the fundamental atmospheric parameters, namely the effective temperature and chemical composition, of these stars by fitting their continua with synthetic spectra computed from pure hydrogen LTE/line-blanketed model atmospheres. The question of the presence (or absence) of trace elements is explored by comparing EUV-determined effective temperatures to the one obtained from a fit of hydrogen balmer lines. It is found that the majority of the DA in the sample are consistent with having a pure hydrogen atmosphere. One of the star, MCT0027-634, is another possible example of a HZ 43-type white dwarf, having an effective temperature above 50000 K and a low heavy element abundance, i.e., much lower than predicted by diffusion theory.

scholarly journals Dust in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 57-62
Author(s):  
Paul Hodge
Keyword(s):  
Heavy Element ◽  
Magellanic Clouds ◽  
Dust Content ◽  
Optical Observations ◽  
Optical Data ◽  
Star Forming ◽  
Element Abundances ◽  
Star Forming Regions ◽  
The Galaxy ◽  
Far Ultraviolet

The dust content of the Magellanic Clouds can be studied using optical, ultraviolet, infrared and, indirectly, radio wavelength data. All recent studies show that the dust content is lower than that of the Milky Way Galaxy for both Clouds and that the optical properties of the dust are different. At ultraviolet wavelengths, the 2165 Å “bump” in the extinction curve is significantly smaller than in the Galaxy (this now appears NOT to be a consequence of the lower heavy element abundances) and the far ultraviolet (shortward of ˜2000 Å) extinction is greater than in the Galaxy (this IS likely to be a consequence of the lower heavy element abundances). New optical data on background galaxies suggest that the total extinction in the central parts of both the LMC and the SMC is approximately 1.5 magnitudes. High local extinction values are derived from uv and optical observations of star-forming regions, where a spatial correlation with CO detections is sometimes, but not always, found.

scholarly journals Interstellar Phases in the Magellanic Clouds

1999 ◽  
Vol 190 ◽  
pp. 45-50 ◽  
Author(s):  
John M. Dickey ◽  
Monika Marx-Zimmer ◽  
Christian Düsterberg ◽  
Ulrich Mebold ◽  
Snezana Stanimirović ◽  
...  
Keyword(s):  
Heavy Element ◽  
Milky Way ◽  
Magellanic Clouds ◽  
Element Abundances ◽  
Lower Abundance ◽  
Cloud Temperature ◽  
Magellanic System

Surveys of λ21-cm absorption in the Magellanic System show that the cool phase of the HI is less abundant in the SMC than in the Milky Way, and may be so also in the LMC. The typical cool cloud temperature is colder than in the Milky Way, 30 to 40 K rather than 60 to 75 K. The lower abundance of cool phase HI can be traced to the lower heavy element abundances in the Magellanic environment. The cooler cloud temperatures are somewhat mysterious.

scholarly journals Element Abundances in Magellanic Cloud H II Regions from Carbon to Argon

1999 ◽  
Vol 190 ◽  
pp. 266-272 ◽  
Author(s):  
Donald R. Garnett
Keyword(s):  
Heavy Element ◽  
Hubble Space Telescope ◽  
Uv Spectroscopy ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
H Ii Regions ◽  
Ionized Gas ◽  
Mixing Processes ◽  
Element Abundances ◽  
C And N

I review measurements of heavy element abundances within H II regions in the Magellanic Clouds, highlighting in particular improved determinations of carbon abundances based on UV spectroscopy with Hubble Space Telescope. In general, the Magellanic Cloud H II regions show average underabundances in O, Ne, and S (relative to their Galactic counterparts) that are similar to those measured in Magellanic Cloud stars. However, comparison of stars and ionized gas shows discrepancies in C and N abundances that may be related to recently recognized mixing processes that may be operating in massive stars.

scholarly journals Element Abundance Analyses of Novae

1977 ◽  
Vol 42 ◽  
pp. 242-273 ◽  
Author(s):  
Robert E. Williams
Keyword(s):  
Temperature Distribution ◽  
Emission Line ◽  
Heavy Element ◽  
Element Abundance ◽  
Element Abundances ◽  
Maximum Light ◽  
Growth Studies ◽  
Nova Shells

AbstractThe different methods by which element abundances in novae have been determined are reviewed. Curve of growth studies of novae at maximum light have indicated CNO nuclei to be greatly enhanced with respect to hydrogen in certain objects. These results are questionable because they depend upon an assumed temperature distribution in the photosphere which is probably too steep to be realistic. Emission line analyses of novae, generally obtained in the period of early decline, also indicate possible heavy element enhancement, however these results are tentative because of uncertainties in the parameters of the emitting gas. It is suggested that useful abundance determinations of nova ejecta might be obtained from studies of old, extended nova shells.

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