scholarly journals Evolution of the abundance of biomolecules in the interstellar medium at the gas phase

2009 ◽  
Vol 5 (S265) ◽  
pp. 438-439
Author(s):  
Eduardo M. Penteado ◽  
Helio J. Rocha-Pinto
Keyword(s):  
Gas Phase ◽  
Chemical Evolution ◽  
Chemical Compositions ◽  
Small Bodies ◽  
Interstellar Clouds ◽  
Elemental Abundances ◽  
Habitable Zones ◽  
Consistent Model ◽  
The Galaxy ◽  
Rocky Planets

AbstractInterstellar clouds are the sites where many molecules believed important for the early life are produced. The collapse of such clouds may give birth to stars hosting planetary systems. During the formation of such systems, molecules formed in the molecular cloud, aggregated into grains, can be incorporated in protoplanets, influencing the chemical evolution of the environment, probably affecting the chances for appearance of life on rocky planets located at the stellar habitable zones. Moreover, small bodies, like comets, can carry some of these molecules to inner planets of their systems. Using astrochemical equations, we describe the evolution of the abundance of such molecules at the gas phase from several initial interstellar compositions. These varying initial chemical compositions consider the change of the elemental abundances predicted by a self-consistent model of the chemical evolution of the Galaxy. A system of first order differential equations that describes the abundances of each molecule is solved numerically. This poster describes an innovative attempt to link the astrochemistry equations with the Galactic chemical evolution.

scholarly journals Carbon Isotopic Chemistry

1992 ◽  
Vol 150 ◽  
pp. 193-197
Author(s):  
W. D. Langer
Keyword(s):  
Chemical Evolution ◽  
Galactic Chemical Evolution ◽  
Interstellar Clouds ◽  
Carbon Isotopic ◽  
The Galaxy ◽  
Molecular Abundances

Isotopic molecular abundances are used to interpret Galactic chemical evolution and the properties of interstellar clouds. The isotopic chemistry of carbon plays an important role in the interpretation of these measurements. This paper reviews the recent measurements of the carbon twelve to thirteen ratio across the Galaxy and the isotopic chemistry.

scholarly journals Impact of Hypernova νp-process Nucleosynthesis on the Galactic Chemical Evolution of Mo and Ru

2022 ◽  
Vol 924 (1) ◽  
pp. 29
Author(s):  
Hirokazu Sasaki ◽  
Yuta Yamazaki ◽  
Toshitaka Kajino ◽  
Motohiko Kusakabe ◽  
Takehito Hayakawa ◽  
...  
Keyword(s):  
Theoretical Prediction ◽  
Observational Data ◽  
Chemical Evolution ◽  
Elemental Abundance ◽  
Core Collapse ◽  
Galactic Chemical Evolution ◽  
Main Contributor ◽  
Elemental Abundances ◽  
The Galaxy ◽  
Low Metallicity

Abstract We calculate the Galactic Chemical Evolution of Mo and Ru by taking into account the contribution from ν p-process nucleosynthesis. We estimate yields of p-nuclei such as 92,94Mo and 96,98Ru through the ν p-process in various supernova progenitors based upon recent models. In particular, the ν p-process in energetic hypernovae produces a large amount of p-nuclei compared to the yield in ordinary core-collapse SNe. Because of this, the abundances of 92,94Mo and 96,98Ru in the Galaxy are significantly enhanced at [Fe/H] = 0 by the ν p-process. We find that the ν p-process in hypernovae is the main contributor to the elemental abundance of 92Mo at low metallicity [Fe/H] < −2. Our theoretical prediction of the elemental abundances in metal-poor stars becomes more consistent with observational data when the ν p-process in hypernovae is taken into account.

scholarly journals Non-LTE Abundances in OB stars: Preliminary Results for 5 Stars in the Outer Galactic Disk

2014 ◽  
Vol 9 (S307) ◽  
pp. 90-91
Author(s):  
G. A. Bragançca ◽  
T. Lanz ◽  
S. Daflon ◽  
K. Cunha ◽  
C. D. Garmany ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Galactic Disk ◽  
B Stars ◽  
Large Sample ◽  
Ob Stars ◽  
Preliminary Results ◽  
Elemental Abundances ◽  
The Galaxy ◽  
Ionization Equilibria ◽  
Chemical Distribution

AbstractThe aim of this study is to analyse and determine elemental abundances for a large sample of distant B stars in the outer Galactic disk in order to constrain the chemical distribution of the Galactic disk and models of chemical evolution of the Galaxy. Here, we present preliminary results on a few stars along with the adopted methodology based on securing simultaneous O and Si ionization equilibria with consistent NLTE model atmospheres.

scholarly journals A systematic study of NLTE abundances of nearby stars

2013 ◽  
Vol 9 (S298) ◽  
pp. 400-400
Author(s):  
Y. Q. Chen ◽  
G. Zhao ◽  
L. Mashonkina ◽  
J. R. Shi ◽  
H. W. Zhang ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Systematic Study ◽  
Stellar Populations ◽  
Thin Disk ◽  
Thick Disk ◽  
Spectral Lines ◽  
Surface Gravity ◽  
Elemental Abundances ◽  
The Galaxy ◽  
Nearby Stars

AbstractApproximately 80 stars from the thin disk, the thick disk and the halo of the Galaxy, in the range of −3.0 < [Fe/H] < +0.5, surface gravity of 3.0 < logg < 4.7 and temperature of 4500 K < Teff < 6500 K, have been observed with the Shane/Hamilton and CFHT/Espadons spectrographs in order to carry out a systematic NLTE study of nearby stars in a consistent way. We will determine reliably stellar parameters and determine precise elemental abundances via a comprehensive NLTE analysis of the spectral lines of Li, Na, Mg, Al, Si, K, Ca, Sc, Mn, Fe, Sr, Zr, Ba, Nd, and Eu elements. Finally, we aim to investigate the chemical evolution of the Galaxy through different stellar populations based on the NLTE abundances for total 15 elements.

scholarly journals Insights on Dust Grain Formation and Destruction Provided by Gas-Phase Element Abundances

1989 ◽  
Vol 135 ◽  
pp. 23-36
Author(s):  
Edward B. Jenkins
Keyword(s):  
Gas Phase ◽  
Normal Density ◽  
Interstellar Clouds ◽  
Element Abundances ◽  
Interstellar Shocks ◽  
Grain Formation ◽  
The Galaxy ◽  
Supernova Explosions ◽  
Solid Form ◽  
Dust Grain

The abundances of free atoms and ions relative to hydrogen in the interstellar medium indicate how thoroughly different elements have condensed into solid form. Large contrasts in these depletions disclose differences in how tightly various elements are bound to the grains. While most grain nuclei probably form within astrophysical sites where densities are large, a substantial amount of the accretion of heavy elements must occur within interstellar clouds. Interstellar shocks created by supernova explosions or perhaps collisions of clouds destroy or significantly erode the grains. This viewpoint on the formation and destruction of grains is supported by the decrease in the severity of depletions in regions of lower than normal density or parcels of gas moving at high velocity. While depletions in gas away from the plane of the galaxy generally imitate the behavior of low density regions in the plane, mild anomalies for some elements may exist.

Mars: was There an Ancient Eden?

1997 ◽  
Vol 161 ◽  
pp. 203-218 ◽  
Author(s):  
Tobias C. Owen
Keyword(s):  
Positive Answer ◽  
Biogenic Elements ◽  
Habitable Zones ◽  
The Face ◽  
The Origin Of Life ◽  
Early Mars ◽  
Favorable Conditions ◽  
Open Question ◽  
Rocky Planets ◽  
Impact Erosion

AbstractThe clear evidence of water erosion on the surface of Mars suggests an early climate much more clement than the present one. Using a model for the origin of inner planet atmospheres by icy planetesimal impact, it is possible to reconstruct the original volatile inventory on Mars, starting from the thin atmosphere we observe today. Evidence for cometary impact can be found in the present abundances and isotope ratios of gases in the atmosphere and in SNC meteorites. If we invoke impact erosion to account for the present excess of129Xe, we predict an early inventory equivalent to at least 7.5 bars of CO2. This reservoir of volatiles is adequate to produce a substantial greenhouse effect, provided there is some small addition of SO2(volcanoes) or reduced gases (cometary impact). Thus it seems likely that conditions on early Mars were suitable for the origin of life – biogenic elements and liquid water were present at favorable conditions of pressure and temperature. Whether life began on Mars remains an open question, receiving hints of a positive answer from recent work on one of the Martian meteorites. The implications for habitable zones around other stars include the need to have rocky planets with sufficient mass to preserve atmospheres in the face of intensive early bombardment.

scholarly journals Abundances in the Gaseous Galactic Halo

1998 ◽  
Vol 11 (1) ◽  
pp. 86-89
Author(s):  
Ulysses J. Sofia
Keyword(s):  
Interstellar Medium ◽  
Gas Phase ◽  
High Velocity ◽  
Galactic Halo ◽  
Solar Neighborhood ◽  
Local Interstellar Medium ◽  
The Galaxy ◽  
Metal Abundances ◽  
High Velocity Clouds

Abstract The well measured gas-phase abundances in the low halo suggest that this region of the Galaxy has total (gas plus dust) metal abundances which are close to those in the solar neighborhood. The gas-phase abundances in the halo are generally higher than those seen in the disk, however, this affect is likely due to the destruction of dust in the halo clouds. Observations of high velocity clouds (HVCs) in the halo suggest that these clouds have metal abundances which are substantially lower than those measured for the local interstellar medium. These determinations, however, are often of lower quality than those for the low halo because of uncertainties in the hydrogen abundances along the sightlines, in the incorporation of elements into dust, and in the partial ionization of the clouds.

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