Carbon abundance in mass-exchanging binaries

1988 ◽  
pp. 221-222
Author(s):  
H. Cugier ◽  
J. P. De Greve
Keyword(s):  
Carbon Abundance

scholarly journals The role of faint population III supernovae in forming CEMP stars in ultra-faint dwarf galaxies

2021 ◽  
Author(s):  
Myoungwon Jeon ◽  
Volker Bromm ◽  
Gurtina Besla ◽  
Jinmi Yoon ◽  
Yumi Choi
Keyword(s):  
Milky Way ◽  
Dwarf Galaxies ◽  
Mass Resolution ◽  
Explosion Energy ◽  
High Carbon ◽  
Cosmological Simulations ◽  
Carbon Abundance ◽  
The Absolute ◽  
Zoom In

Abstract CEMP-no stars, a subset of carbon enhanced metal poor (CEMP) stars ($\rm [C/Fe]\ge 0.7$ and $\rm [Fe/H]\lesssim -1$) have been discovered in ultra-faint dwarf (UFD) galaxies, with Mvir ≈ 108 M⊙ and M* ≈ 103 − 104 M⊙ at z = 0, as well as in the halo of the Milky Way (MW). These CEMP-no stars are local fossils that may reflect the properties of the first (Pop III) and second (Pop II) generation of stars. However, cosmological simulations have struggled to reproduce the observed level of carbon enhancement of the known CEMP-no stars. Here we present new cosmological hydrodynamic zoom-in simulations of isolated UFDs that achieve a gas mass resolution of mgas ≈ 60 M⊙. We include enrichment from Pop III faint supernovae (SNe), with ESN = 0.6 × 1051 erg, to understand the origin of CEMP-no stars. We confirm that Pop III and Pop II stars are mainly responsible for the formation of CEMP and C-normal stars respectively. New to this study, we find that a majority of CEMP-no stars in the observed UFDs and the MW halo can be explained by Pop III SNe with normal explosion energy (ESN = 1.2 × 1051 erg) and Pop II enrichment, but faint SNe might also be needed to produce CEMP-no stars with $\rm [C/Fe]\gtrsim 2$, corresponding to the absolute carbon abundance of $\rm A(C)\gtrsim 6.0$. Furthermore, we find that while we create CEMP-no stars with high carbon ratio $\rm [C/Fe]\approx 3-4$, by adopting faint SNe, it is still challenging to reproduce CEMP-no stars with extreme level of carbon abundance of $\rm A(C)\approx 7.0-7.5$, observed both in the MW halo and UFDs.

scholarly journals The Galactic Ecosystem

2004 ◽  
Vol 213 ◽  
pp. 123-126
Author(s):  
Michael Burton
Keyword(s):  
Star Formation ◽  
Crucial Role ◽  
Self Regulation ◽  
Spiral Arms ◽  
Carbon Abundance

We discuss how the process of star formation across the spiral arms of galaxies functions as an ecosystem. The carbon abundance plays a crucial role in both its self-regulation and evolution.

scholarly journals Peculiar J-type Carbon Stars and Li

2000 ◽  
Vol 198 ◽  
pp. 506-507
Author(s):  
S. Lorenz-Martins ◽  
N. A. Drake
Keyword(s):  
High Resolution ◽  
Spectral Region ◽  
Resonance Line ◽  
Spectral Synthesis ◽  
Synthesis Method ◽  
Isotopic Ratios ◽  
Carbon Stars ◽  
Carbon Isotopic ◽  
Carbon Abundance ◽  
Extended Range

We determined the carbon and lithium abundances and carbon isotopic ratios for 4 peculiar carbon stars by means of spectral synthesis method. Li abundances were derived using Li resonance line at λ6707.8 Â. For carbon abundance determinations we used the lines of the red system of CN molecule. Spectral region of λλ7994 — 8030 Â containing the lines of molecules 12CN and 13CN was used also for 12C/13C ratio measuring. The high-resolution spectra were obtained on the 1.52m telescope of ESO with the Fiber-fed Extended Range Optical Spectrograph (FEROS). These observations were obtained under the agreement between the CNPq-Observatório Nacional, Brazil, and ESO.

scholarly journals Interpretation of the Ultraviolet Spectrum of NGC 7662

1978 ◽  
Vol 76 ◽  
pp. 121-122
Author(s):  
R.C. Bohlin ◽  
J.P. Harrington ◽  
T.P. Stecher
Keyword(s):  
Neutral Hydrogen ◽  
Central Star ◽  
Dielectronic Recombination ◽  
Emission Lines ◽  
Ultraviolet Emission ◽  
Two Photon ◽  
Carbon Abundance ◽  
Photon Process ◽  
Ngc 7662

The ultraviolet emission lines that were me asured in the spectrum obtained from our rocket observation of NGC 7662 have been compared with those predicted by a set of models. The models allow a determination of the carbon abundance which is found to be solar and the C/0 ratio which is equal to unity. In order to obtain a good fit, dielectronic recombination and charge exchange between neutral hydrogen and C IV were included, both of which increase the concentration of C III. The observed continuum consists of light from the central star and from the nebula, which contributed primarily via the two photon process in the H° and the Balmer continuum.

scholarly journals Carbon Depletion in Case B Mass Transfer Algol-Type Binaries

1992 ◽  
Vol 151 ◽  
pp. 355-358
Author(s):  
Tae S. Yoon ◽  
Kent Honeycutt
Keyword(s):  
Mass Transfer ◽  
Mass Loss ◽  
Similar Type ◽  
Single Star ◽  
Star Models ◽  
Promising Tool ◽  
Carbon Abundance ◽  
Processed Material ◽  
C And N ◽  
Larger Sample

The surface carbon abundances of Algol secondaries are known to be low compared to field stars of similar type. The C and N anomalies of these G and K subgiants are undoubtedly due to the exposure of CN cycle processed material as mass transfer removes the outer layers of the star. Therefore the carbon abundance is a promising tool for helping fix the evolutionary state of Algols, particularly the amount of mass which has been lost from the secondary. We report here the carbon abundance of 12 Algol secondaries as deduced from the g-band in spectra obtained during photometric totality. We compare the abundances to those from models of single stars of appropriate age and mass. The values of log ∊(C) for this sample fall 0.25–0.75 dex below field G and K giants, and 1.25–1.75 dex above “stripped” single star models. This larger sample supports the conclusions of Parthasarthy et al. regarding mixing and mass loss, which they deduced from a smaller sample of carbon abundances.

The interstellar carbon abundance toward Delta Scorpii

1982 ◽  
Vol 252 ◽  
pp. L21 ◽  
Author(s):  
L. M. Hobbs ◽  
D. G. York ◽  
W. Oegerle
Keyword(s):  
Carbon Abundance

scholarly journals A method for mapping the aliphatic hydrocarbon content of interstellar dust towards the Galactic Centre

2020 ◽  
Vol 493 (1) ◽  
pp. 1109-1119
Author(s):  
B Günay ◽  
M G Burton ◽  
M Afşar ◽  
T W Schmidt
Keyword(s):  
Interstellar Dust ◽  
Elemental Carbon ◽  
Total Carbon ◽  
Galactic Centre ◽  
Absorption Feature ◽  
Ir Camera ◽  
Carbon Abundance ◽  
The Galaxy ◽  
Aliphatic Carbon

ABSTRACT In the interstellar medium, the cosmic elemental carbon abundance includes the total carbon in both gas and solid phases. The aim of the study was to trial a new method for measuring the amount and distribution of aliphatic carbon within interstellar dust over wide fields of view of our Galaxy. This method is based on the measurement of the 3.4-$\mu$m absorption feature from aliphatic carbonaceous matter. This can readily be achieved for single sources using infrared (IR) spectrometers. However, making such measurements over wide fields requires an imaging IR camera, equipped with narrow-band filters that are able to sample the spectrum. While this cannot produce as good a determination of the spectra, the technique can be applied to potentially tens to hundreds of sources simultaneously, over the field of view of the camera. We examined this method for a field in the centre of the Galaxy, and produced a map showing the variation of 3.4-$\mu$m optical depth across it.

scholarly journals THE BORON-TO-CARBON ABUNDANCE RATIO AND GALACTIC PROPAGATION OF COSMIC RADIATION

2012 ◽  
Vol 752 (1) ◽  
pp. 69 ◽  
Author(s):  
A. Obermeier ◽  
P. Boyle ◽  
J. Hörandel ◽  
D. Müller
Keyword(s):  
Cosmic Radiation ◽  
Abundance Ratio ◽  
Carbon Abundance
Sign in / Sign up

Export Citation Format

Share Document