Supernovae, Superbubbles, Nonthermal Emission & Light Element Nucleosynthesis in the Galaxy

2001 ◽  
pp. 43-64
Author(s):  
Andrei M. Bykov
Keyword(s):  
Light Element ◽  
Nonthermal Emission ◽  
The Galaxy ◽  
Emission Light

scholarly journals Light element discontinuities suggest an early termination of star formation in the globular cluster NGC 6402 (M14)

2019 ◽  
Vol 485 (3) ◽  
pp. 4311-4329 ◽  
Author(s):  
Christian I Johnson ◽  
Nelson Caldwell ◽  
R Michael Rich ◽  
Mario Mateo ◽  
John I Bailey
Keyword(s):  
Globular Clusters ◽  
First Generation ◽  
Light Element ◽  
Chemical Abundances ◽  
Intermediate Composition ◽  
Chemical Enrichment ◽  
The Galaxy ◽  
Red Giant ◽  
Composition Properties ◽  
Delayed Phase

ABSTRACT NGC 6402 is among the most massive globular clusters in the Galaxy, but little is known about its detailed chemical composition. Therefore, we obtained radial velocities and/or chemical abundances of 11 elements for 41 red giant branch stars using high resolution spectra obtained with the Magellan-M2FS instrument. We find NGC 6402 to be only moderately metal-poor with 〈[Fe/H]〉 = −1.13 dex (σ = 0.05 dex) and to have a mean heliocentric radial velocity of −61.1 km s−1 (σ = 8.5 km s−1). In general, NGC 6402 exhibits mean composition properties that are similar to other inner Galaxy clusters, such as [α/Fe] ∼+0.3 dex, [Cr,Ni/Fe] ∼ 0.0 dex, and 〈[La/Eu]〉 = −0.08 dex. Similarly, we find large star-to-star abundance variations for O, Na, Mg, Al, and Si that are indicative of gas that experienced high temperature proton-capture burning. Interestingly, we not only detect three distinct populations but also find large gaps in the [O/Fe], [Na/Fe], and [Al/Fe] distributions that may provide the first direct evidence of delayed formation for intermediate composition stars. A qualitative enrichment model is discussed where clusters form stars through an early ($\lesssim$5–10 Myr) phase, which results in first generation and ‘extreme’ composition stars, and a delayed phase ($\gtrsim$40 Myr), which results in the dilution of processed and pristine gas and the formation of intermediate composition stars. For NGC 6402, the missing intermediate composition stars suggest the delayed phase terminated prematurely, and as a result the cluster may uniquely preserve details of the chemical enrichment process.

scholarly journals Nonthermal emission from the radio relic of the galaxy cluster A2256

2011 ◽  
Vol 332 (6) ◽  
pp. 649-654 ◽  
Author(s):  
G. Siemieniec-Ozieblo ◽  
B.M. Pasternak
Keyword(s):  
Galaxy Cluster ◽  
Nonthermal Emission ◽  
The Galaxy

scholarly journals Lithium Abundances of Solar-Type Stars in Open Clusters

1995 ◽  
Vol 10 ◽  
pp. 447-448
Author(s):  
D.R. Soderblom
Keyword(s):  
Light Element ◽  
Big Bang ◽  
Open Clusters ◽  
Spectroscopic Feature ◽  
The Galaxy ◽  
Solar Type ◽  
Good Signal ◽  
Large Telescopes ◽  
The Big Bang ◽  
Over Time

This paper discusses the lithium abundances of late-F through mid-F dwarfs in the nearby open clusters. That means that I am considering young disk stars, of course, with metallicities similar to the Sun’s. I will not discuss the chasm seen among mid-F dwarfs. Li is not easily studied because only one spectroscopic feature is available and that feature is often weak. Thus high spectroscopic resolution and good signal to noise are needed. But Li is still the most easily studied of the light-element pentateuch (D, He, Li, Be, B).The few clusters now accessible to large telescopes at high spectroscopic resolution include the Hyades, Pleiades, a Persei, as well as smaller samples in a few others (such as Coma, M67, NGC 752, the Ursa Major Group). The samples within clusters are often substantial, and allow one to examine differences in Li between stars of the same mass, age, and composition. However the total number of clusters observed is still small, so one must assume that each cluster is fully representative for its age and composition.Much recent work on Li in stars has been for Population II objects because of the importance of Li for cosmology. We study Li in Pop I stars for three reasons: First, to understand how the Galaxy has come to be enriched in Li since the Pop II stars formed. Second, to understand the stellar physics behind Li depletion in Pop I stars as a means to understanding what happens in the outer layers of such a star over time. Third, to apply that understanding of the stellar physics to Pop II stars so we can correctly infer the Big Bang Li abundance.

scholarly journals Rediscovering the origins of the stellar halo with chemical tagging

2017 ◽  
Vol 13 (S334) ◽  
pp. 38-42 ◽  
Author(s):  
Sarah L Martell
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Galactic Halo ◽  
Light Element ◽  
Element Abundance ◽  
Tidal Interactions ◽  
Halo Stars ◽  
The Galaxy ◽  
Stellar Halo ◽  
Light Element Abundance

AbstractThe Galactic halo has a complex assembly history, which can be seen in its wealth of kinematic and chemical substructure. Globular clusters lose stars through tidal interactions with the Galaxy and cluster evaporation processes, meaning that they are inevitably a source of halo stars. These “migrants” from globular clusters can be recognized in the halo field by the characteristic light element abundance anticorrelations that are commonly observed only in globular cluster stars, and the number of halo stars that can be chemically tagged to globular clusters can be used to place limits on the formation pathways of those clusters.

scholarly journals NGC 5128 - a nearby laboratory for planetary nebulae in a giant early-type galaxy

2011 ◽  
Vol 7 (S283) ◽  
pp. 279-282
Author(s):  
Jeremy R. Walsh ◽  
George H. Jacoby ◽  
Harald Kuntschner ◽  
Reynier F. Peletier ◽  
Marina Rejkuba ◽  
...  
Keyword(s):  
Stellar Population ◽  
Elliptical Galaxy ◽  
Light Element ◽  
Forthcoming Paper ◽  
Radial Gradient ◽  
Element Abundances ◽  
The Galaxy ◽  
Galaxy Kinematics ◽  
History Of ◽  
Early Type Galaxy

AbstractNGC 5128 at 3.8 Mpc is the nearest large elliptical galaxy and is ideally suited to a detailed study of its planetary nebula population. Two spectroscopic programmes are summarised. More than 1200 PNe candidates are known from imaging campaigns in NGC 5128 and accurate radial velocities of 1070 have been measured with the VLT FLAMES/Giraffe spectrometer. From these data a variety of studies of the galaxy kinematics are enabled, such as search for PN sub-groups, representing the relics of accretion of small galaxies. Emission line spectra were observed with VLT FORS and the light element abundances determined for 40 PNe through photoionization modelling. A spread in O abundance of about 0.9 dex is found but no obvious radial gradient out to 19 kpc. Comparison of the O abundance from these PN with the metallicity for the stellar population in the neighbourhood of the PN will probe the star formation and enrichment history of the galaxy. Full results from this analysis will be presented in a forthcoming paper.

Galactic nonthermal radiation. Distribution of SNRs and pulsars

1979 ◽  
Vol 84 ◽  
pp. 113-118
Author(s):  
R. Wielebinski
Keyword(s):  
Supernova Remnants ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Hii Regions ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Nonthermal Radiation ◽  
Radiation Distribution ◽  
Nonthermal Emission ◽  
The Galaxy

All sky surveys of the radio continuum emission give us the basic information on the distribution of the nonthermal emission in the Galaxy. At metre wavelengths, where nonthermal emission is dominant, good angular resolution is difficult to attain. For many years the best surveys near 2 m wavelength gave us a picture of the galaxy with ∼ 2° resolution. At centimetre wavelengths, where arc min resolution is available, the intense HII regions dominate the radio sky. Supernova remnants have a distribution somewhat similar to that of the discrete HII regions and must be delineated by various methods in high resolution galactic plane surveys in the decimetre wavelength range.

Light element discontinuities in the globular cluster NGC 6402 (M14)

2019 ◽  
Vol 14 (S351) ◽  
pp. 305-308
Author(s):  
Christian I. Johnson
Keyword(s):  
Star Formation ◽  
Chemical Composition ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Light Element ◽  
Early Termination ◽  
Intermediate Composition ◽  
The Galaxy ◽  
Detailed Chemical

AbstractNGC 6402 is one of the most massive globular clusters in the Galaxy but until recently little was known about its detailed chemical composition. Interestingly, recent results have shown that NGC 6402 exhibits a paucity of intermediate composition stars that may be indicative of an early termination of star formation. As a result, NGC 6402 may be important for understanding cluster formation and the order in which various stellar populations are born.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

Density waves in disk galaxies

1967 ◽  
Vol 31 ◽  
pp. 313-317 ◽  
Author(s):  
C. C. Lin ◽  
F. H. Shu
Keyword(s):  
Mathematical Analysis ◽  
Spiral Structure ◽  
Stellar System ◽  
Collective Modes ◽  
Disk Galaxies ◽  
Spiral Pattern ◽  
Density Waves ◽  
The Galaxy ◽  
Detailed Mathematical Analysis

Density waves in the nature of those proposed by B. Lindblad are described by detailed mathematical analysis of collective modes in a disk-like stellar system. The treatment is centered around a hypothesis of quasi-stationary spiral structure. We examine (a) the mechanism for the maintenance of this spiral pattern, and (b) its consequences on the observable features of the galaxy.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

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