scholarly journals Metal abundances in the MACER simulations of the hot interstellar medium

2020 ◽  
Vol 341 (2) ◽  
pp. 184-190 ◽  
Author(s):  
Silvia Pellegrini ◽  
Zhaoming Gan ◽  
Jeremiah P. Ostriker ◽  
Luca Ciotti
Keyword(s):  
Interstellar Medium ◽  
Metal Abundances

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.

XMM‐NewtonObservations of NGC 507: Supersolar Metal Abundances in the Hot Interstellar Medium

2004 ◽  
Vol 613 (2) ◽  
pp. 933-947 ◽  
Author(s):  
Dong‐Woo Kim ◽  
Giuseppina Fabbiano
Keyword(s):  
Interstellar Medium ◽  
Metal Abundances

scholarly journals Suzaku observation of the metallicity in the interstellar medium of NGC 1316

2009 ◽  
Vol 5 (H15) ◽  
pp. 286-286
Author(s):  
S. Konami ◽  
K. Matsushita ◽  
K. Sato ◽  
R. Nagino ◽  
N. Isobe ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Mass Loss ◽  
Elliptical Galaxies ◽  
Stellar Mass ◽  
Metal Enrichment ◽  
Abundance Pattern ◽  
Type Ia ◽  
History Of ◽  
Metal Abundances ◽  
Formation And Evolution

Metal abundances of the hot X-ray emitting interstellar medium (ISM) include important information to understand the history of star formation and evolution of galaxies. The metals are mainly synthesized by Type Ia (SNe Ia) and stellar mass loss in elliptical galaxies. The productions of stellar mass loss reflect stellar metallicity. SNe Ia mainly product Fe. Therefore, the abundance pattern of ISM can play key role to investigate the metal enrichment history.

Interstellar Gas Dynamics

1968 ◽  
Vol 1 (3) ◽  
pp. 96-96
Author(s):  
M.E. Dixon
Keyword(s):  
Chemical Composition ◽  
Interstellar Medium ◽  
Gas Dynamics ◽  
Young Stars ◽  
Observational Result ◽  
Interstellar Gas ◽  
Present Epoch ◽  
Metal Abundances

It is a well established observational result that young stars exhibit differences in chemical composition. The differences are comparatively large. For example, some stars have metal abundances as high as 3/2 solar-value while others have abundances as low as 1/2 solar-value. The result was obtained through spectroscopic and photoelectric studies of stars with ages of a few times 108 yr and indicates that the interstellar medium is chemically heterogeneous at the present epoch.

scholarly journals The Contribution of Hipparcos to the Study of the Stellar Metal-Rich Population in the Solar Neighbourhood

1998 ◽  
Vol 11 (1) ◽  
pp. 566-566
Author(s):  
G. Cayrel de Strobel ◽  
C. Soubiran ◽  
Y. Lebreton
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Evolved Stars ◽  
Spectroscopic Analyses ◽  
The Galaxy ◽  
Solar Metallicity ◽  
Metal Abundances ◽  
The Mean ◽  
Effective Temperatures ◽  
Absolute Magnitudes

The ‘1996 Edition’ of the Catalogue of [Fe/H] determinations by Cayrel de Strobel et al. (1997, A&A S 124,1) and two recent papers by Castro et al. (1997, AJ Vol.114, N.1) and by Feltzing and Gustafsson (A&A in press) have made possible to increase in the theoretical HR diagram (log Teff, Mbol the number of SMR stars. The SMR Stars of this new enlarged sample had to have reliable absolute magnitudes, coming all from Hipparcos parallaxes, precise bolometric corrections, effective temperatures and metal abundances from high resolution detailed spectroscopic analyses. With the help of an appropriate grid of isochrones computed by Lebreton (1997, Perryman et al. A&A, in press), ‘turn-off ages’could then be attributed to the slightly evolved stars (subgiants) of the sample. The (log Teff, Mbol) diagram constituted by the new sample of SMR stars, shows that the conclusions in a former paper by Cayrel de Strobel (1987, A&AJ 8,141) remain valid: the SMR stars areold stars in spite of their higher than solar metallicity. The result, that metal-rich stars were in the mean old stars, was interpreted in the 1987 paper as due to a more chemical uniformity of the nowadays interstellar medium of the Galaxy with respect of the older much more active interstellar medium.

scholarly journals Lyman Alpha Emitting Galaxies in the Nearby Universe

2015 ◽  
Vol 32 ◽  
Author(s):  
Matthew Hayes
Keyword(s):  
Interstellar Medium ◽  
Large Scale ◽  
Neutral Hydrogen ◽  
Emission Feature ◽  
Ultraviolet Continuum ◽  
Lyman Alpha ◽  
Alpha Emission ◽  
Multi Wavelength ◽  
Metal Abundances ◽  
Galaxy Population

AbstractThe Lyman alpha emission line (Lyα) of neutral hydrogen (Hi) is intrinsically the brightest emission feature in the spectrum of astrophysical nebulae, making it a very attractive observational feature with which to survey galaxies. Moreover as an ultraviolet resonance line, Lyα possesses several unique characteristics that make it useful to study the properties of the interstellar medium and ionising stellar population at all cosmic epochs. In this review, I present a summary of Lyα observations of galaxies in the nearby universe. By ultraviolet continuum selection, at the magnitudes reachable with current facilities, only ≈ 5% of the local galaxy population shows a Lyα equivalent width (WLyα) that exceeds 20 Å. This fraction increases dramatically at higher redshifts, but only in the local universe can we study galaxies in detail and assemble unprecedented multi-wavelength datasets. I discuss many local Lyα observations, showing that when galaxies show net Lyα emission, they ubiquitously also produce large-scale halos of scattered Lyα, that dominate the integrated luminosity. Concerning global measurements, we discuss how WLyα and the Lyα escape fraction (fLyαesc) are higher (WLyα ≳ 20 Å and fLyαesc ≳ 10%) in galaxies that represent the less massive and younger end of the distribution for local objects. This is connected with various properties, such that Lyα-emitting galaxies have lower metal abundances (median value of 12 + log(O/H) ~ 8.1) and dust reddening. However, the presence of galactic outflows/winds is also vital to Doppler shift the Lyα line out of resonance with the atomic gas, and high WLyα is found only among galaxies with winds faster than ~ 50 km s−1. The empirical evidence is then assembled into a coherent picture, and the requirement for star-formation-driven feedback is discussed in the context of an evolutionary sequence where the interstellar medium is accelerated and/or subject to hydrodynamical instabilities, which reduce the scattering of Lyα. Concluding remarks take the form of perspectives upon future developments, and the most pressing questions that can be answered by observation.

scholarly journals A minimum dilution scenario for supernovae and consequences for extremely metal-poor stars

2020 ◽  
Vol 498 (3) ◽  
pp. 3703-3712 ◽  
Author(s):  
Mattis Magg ◽  
Thomas Nordlander ◽  
Simon C O Glover ◽  
Camilla J Hansen ◽  
Miho Ishigaki ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Spherical Symmetry ◽  
Chemical Elements ◽  
First Stars ◽  
Abundance Pattern ◽  
Metal Free ◽  
Chemical Enrichment ◽  
Direct Observations ◽  
Abundance Patterns ◽  
Metal Abundances

ABSTRACT To date no metal-free stars have been identified by direct observations. The most common method of constraining their properties is searching the spectra of the most metal-poor stars for the chemical elements created in the first stars and their supernova (SN). In this approach, modelled SN yields are compared to the observed abundance patterns in extremely metal-poor stars. The method typically only uses the abundance ratios, i.e. the yields are diluted to the observed level. Following the usual assumption of spherical symmetry we compute a simple lower limit of the mass an SN can mix with and find that it is consistent with all published simulations of early chemical enrichment in the interstellar medium. For three different cases, we demonstrate that this dilution limit can change the conclusions from the abundance fitting. There is a large discrepancy between the dilution found in simulations of SN explosions in minihaloes and the dilution assumed in many abundance fits. Limiting the dilution can significantly alter the likelihood of which supernovae are possible progenitors of observed CEMP-no stars. In particular, some of the faint, very low yield SNe, which have been suggested as models for the abundance pattern of SMSS0313−6708, cannot explain the measured metal abundances, as their predicted metal yields are too small by two orders of magnitude. Altogether, the new dilution model presented here emphasizes the need to better understand the mixing and dilution behaviour of aspherical SNe.

scholarly journals Galactic evolution and the two-colour diagram

1964 ◽  
Vol 20 ◽  
pp. 37-37
Author(s):  
R. H. Stoy
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Past History ◽  
Photometric Data ◽  
Galactic Evolution ◽  
The Past ◽  
The Galaxy ◽  
History Of ◽  
Present Distribution ◽  
Metal Abundances

Information about the past history of the Galaxy may be obtained from a two-colour diagram, since the present distribution of stars in such a diagram depends on the past rate of star formation and the past metal abundances in the interstellar medium. As an illustration of this, I would like to discuss three diagrams that were recently prepared by Dr. M. E. Dixon from Cape photometric data (Dixon 1963a,b).

scholarly journals Large Metallicity Variations in the Galactic Interstellar Medium

2020 ◽  
Author(s):  
Annalisa De Cia ◽  
Edward Jenkins ◽  
Cedric Ledoux ◽  
Andrew Fox ◽  
Tanita Ramburth-Hurt ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Hubble Space Telescope ◽  
Galactic Disk ◽  
Cosmic Dust ◽  
Evolution Of Galaxies ◽  
Very Large Telescope ◽  
Metal Abundances ◽  
Low Metallicity ◽  
Formation And Evolution ◽  
High Velocity Clouds

Abstract Metals in the neutral Interstellar Medium (ISM) of galaxies are crucial for the formation and evolution of galaxies, stars, cosmic dust, molecules, and planets. However, understanding the metal abundances in the neutral ISM is complicated by the presence of cosmic dust. Large quantities of metals are missing from the observable gas-phase because they are incorporated into dust grains. This phenomenon is called dust depletion. Until recently, the metallicity of the neutral ISM in the vicinity of the Sun was assumed to be Solar. In this paper we directly measure the metallicity of the neutral ISM, by quantifying dust depletion without making as- sumptions on the gas metallicity, using Hubble Space Telescope (HST) and Very Large Telescope (VLT) spectra of 25 hot bright stars. We find that the dust-corrected metal- licity in the neutral ISM in our Galaxy is not always Solar, but shows large variations spreading over a factor of 10 and including many regions of low metallicity, down to ∼ 17% Solar and possibly below. Pristine gas infalling towards the Galactic disk in the form of intermediate and high-velocity clouds could cause the observed chemical inhomogeneities on scales of tens of pc. This has a profound impact for the chemical evolution of galaxies.

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