Symbiotic Stars at Optical, Infrared and Radio Wavelengths

1979 ◽  
Vol 46 ◽  
pp. 125-149 ◽  
Author(s):  
David A. Allen
Keyword(s):  
Temperature Regime ◽  
Type Star ◽  
Stellar Systems ◽  
Symbiotic Stars ◽  
Lower Excitation ◽  
Definition Of ◽  
Original Type

No paper of this nature should begin without a definition of symbiotic stars. It was Paul Merrill who, borrowing on his botanical background, coined the termsymbioticto describe apparently single stellar systems which combine the TiO absorption of M giants (temperature regime ≲ 3500 K) with He II emission (temperature regime ≳ 100,000 K). He and Milton Humason had in 1932 first drawn attention to three such stars: AX Per, CI Cyg and RW Hya. At the conclusion of the Mount Wilson Ha emission survey nearly a dozen had been identified, and Z And had become their type star. The numbers slowly grew, as much because the definition widened to include lower-excitation specimens as because new examples of the original type were found. In 1970 Wackerling listed 30; this was the last compendium of symbiotic stars published.

The Symbiotic Star H1-36

1983 ◽  
Vol 5 (2) ◽  
pp. 211-213 ◽  
Author(s):  
David A. Allen
Keyword(s):  
Emission Line ◽  
Planetary Nebula ◽  
Line Spectrum ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
High Excitation ◽  
Infrared Excess ◽  
Emission Line Spectrum ◽  
Definition Of ◽  
Meaningful Definition

Since its discovery by Haro (1952) the star H1-36 has been catalogued as a planetary nebula despite its extremely high-excitation emission-line spectrum (e.g. [Fe VII], [Ne V]) and its imposing, variable infrared excess. Because its optical spectrum resembled those of many symbiotic stars, I have persistently classified H1-36 as such. A meaningful definition of a symbiotic star would necessarily include both the high-excitation emission-line spectrum and the presence of a cool (usually M-type or Mira) giant.

scholarly journals Ultraviolet Classification from the S2/68 Experiment on Board the Tdia Satellite

1979 ◽  
Vol 47 ◽  
pp. 435-437
Author(s):  
A. Cucchiaro
Keyword(s):  
Statistical Study ◽  
Classification Scheme ◽  
Type Star ◽  
Two Dimensional ◽  
Morphology Analysis ◽  
Dimensional Classification ◽  
Intensity Ratios ◽  
Line Features ◽  
Definition Of ◽  
Made In

A morphology analysis as well as a statistical study of the spectra provided by the S2/68 experiment is made in order to establish ultraviolet criteria of classification. These criteria, either line features or intensity ratios, permit the establishment of a two-dimensional classification to be made from the so-called B0 to G0 type star in the classic range. This classification scheme permits also “abnormal” spectra to be singled out, thanks to the definition of the “normal” spectra.

Properties of symbiotic stars from studies in the optical region

1982 ◽  
Vol 70 ◽  
pp. 61-70
Author(s):  
Franco Ciatti
Keyword(s):  
Emission Lines ◽  
Symbiotic Stars ◽  
Coronal Emission ◽  
Optical Region ◽  
Type Giant ◽  
Definition Of ◽  
High Degree ◽  
Absorption Features ◽  
Excitation Conditions ◽  
The Continuum

The traditional definition of Symbiotic Stars (SS) is that of objects which display a combination spectrum (e.g. Merrill, 1950) that is emission lines requiring high-excitation conditions, superposed to the continuum and absorption features of a low-temperature star, most commonly an M-type giant. About one hundred of SS are known and listed today. It is anyway apparent that the classification criteria are rather rough, and since the excitation varies from the simple Me to SS with coronal emission, it is not well defined where a clear division should be made. As a result, the available lists include a very heterogeneous set of objects, probably different phases in stellar evolution. Moreover it has been remarked that SS show a rather confusing variety in their spectroscopic and photometric behaviour. Different intensities of both absorption and emission lines are reported from star to star. These facts indicate a high degree of individuality among SS, which is partly cause and/or effect of the adopted definitions.

scholarly journals Optical and Near-IR Monitoring of Symbiotic Binary Systems

2001 ◽  
Vol 183 ◽  
pp. 167-176
Author(s):  
Joanna Mikołajewska
Keyword(s):  
Binary Systems ◽  
Variable Stars ◽  
Type Star ◽  
Symbiotic Stars ◽  
Future Prospects ◽  
Dust Shell ◽  
Giant Star ◽  
Long Period ◽  
Near Ir ◽  
Red Giant

AbstractSymbiotic stars are long-period interacting binary systems in which an evolved red giant star transfers material to its much hotter compact companion. Such a composition places them among the most variable stars. In addition to periodic variations due to the binary motion, they often show irregular changes due to nova-like eruptions of the hot component. In some systems the cool giant is a pulsating Mira-type star usually surrounded by a variable dust shell. Here, I present results of optical and IR monitoring of symbiotic systems as well as future prospects for such studies.

scholarly journals Exotic populations in globular clusters: blue stragglers as tracers of the internal dynamical evolution of stellar systems

2014 ◽  
Vol 10 (S312) ◽  
pp. 171-180
Author(s):  
Francesco R. Ferraro
Keyword(s):  
Radial Distribution ◽  
Globular Clusters ◽  
Stellar Population ◽  
Dynamical Evolution ◽  
Stellar Systems ◽  
Internal Dynamics ◽  
Blue Stragglers ◽  
Blue Straggler ◽  
Specific Frequency ◽  
Definition Of

AbstractIn this paper I present an overview of the main observational properties of a special class of exotic objects (the so-called Blue Straggler Stars, BSSs) in Galactic Globular Clusters (GCs). The BSS specific frequency and their radial distribution are discussed in the framework of using this stellar population as probe of GC internal dynamics. In particular, the shape of the BSS radial distribution has been found to be a powerful tracer of the dynamical evolution of stellar systems, thus allowing the definition of an empirical “clock”able to measure the dynamical age of stellar aggregates from pure observational properties.

An empirical clock to measure the dynamical age of star clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 377-383
Author(s):  
Francesco R. Ferraro
Keyword(s):  
Radial Distribution ◽  
Special Class ◽  
Globular Clusters ◽  
Stellar Population ◽  
Star Clusters ◽  
Dynamical Evolution ◽  
Stellar Systems ◽  
Central Segregation ◽  
Blue Straggler ◽  
Definition Of

AbstractThe observational properties of a special class of stars (the so-called Blue Straggler stars - BSSs) in Globular Clusters are discussed in the framework of using this stellar population as probe of the dynamical processes occurring in high-density stellar systems. In particular, the shape of the BSS radial distribution and their level of central segregation have been found to be powerful tracers of the level of the dynamical evolution of the hosting cluster, thus allowing the definition of an empirical chronometer able to measure the dynamical age of star clusters.

Containers, monads and induction recursion

2014 ◽  
Vol 26 (1) ◽  
pp. 89-113 ◽  
Author(s):  
NEIL GHANI ◽  
PETER HANCOCK
Keyword(s):  
Programming Language ◽  
Algebraic Structure ◽  
Functional Programming ◽  
Type System ◽  
Pivotal Role ◽  
A Value ◽  
Structural Recursion ◽  
Definition Of ◽  
High Level ◽  
Original Type

Induction recursion offers the possibility of a clean, simple and yet powerful meta-language for the type system of a dependently typed programming language. At its crux, induction recursion allows us to define a universe, that is a setUofcodesand a decoding functionT : U → Dwhich assigns to every codeu : U, a valueT, uof some typeD, e.g.the large type Set of small types or sets. The name induction recursion refers to the build-up of codes inUusing inductive clauses, simultaneously with the definition of the functionT, by structural recursion on codes.Our contribution is to (i) bring out explicitly algebraic structure which is less visible in the original type-theoretic presentation – in particular showing how containers and monads play a pivotal role within induction recursion; and (ii) use these structures to present a clean and high level definition of induction recursion suitable for use in functional programming.

Introductory paper

1966 ◽  
Vol 24 ◽  
pp. 3-5
Author(s):  
W. W. Morgan
Keyword(s):  
Line Intensity ◽  
Classification Scheme ◽  
Two Dimensional ◽  
Spectral Classification ◽  
Dimensional Array ◽  
Rr Lyrae ◽  
Metallic Line ◽  
Introductory Paper ◽  
Parameter Varying ◽  
Definition Of

1. The definition of “normal” stars in spectral classification changes with time; at the time of the publication of theYerkes Spectral Atlasthe term “normal” was applied to stars whose spectra could be fitted smoothly into a two-dimensional array. Thus, at that time, weak-lined spectra (RR Lyrae and HD 140283) would have been considered peculiar. At the present time we would tend to classify such spectra as “normal”—in a more complicated classification scheme which would have a parameter varying with metallic-line intensity within a specific spectral subdivision.

Desiderata in connection by the calibration of the MK-system

1966 ◽  
Vol 24 ◽  
pp. 348-349
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Absolute Magnitude ◽  
Review Article ◽  
Stellar Systems ◽  
Astronomical Data ◽  
Intrinsic Colour

This is only an informal remark about some difficulties I am worrying about.I have tried to recalibrate the MK system in terms of intrinsic colour (B–V)0and absolute magnitudeMv. The procedures used have been described in a review article by Voigt (Mitt. Astr. Ges.1963, p. 25–35), and the results for stars of the luminosity classes Ia-O,I and II have been given also in Blaauw's article on the calibration of luminosity criteria in vol. III (Basic Astronomical Data, p. 401) ofStars and Stellar Systems.

2.2. Working Group 2: Conceptual Definitions of Reference Coordinate Systems for Earth Dynamics

1975 ◽  
Vol 26 ◽  
pp. 21-26
Keyword(s):  
Coordinate System ◽  
Working Group ◽  
General Character ◽  
Coordinate Systems ◽  
Reference Coordinate System ◽  
Group 2 ◽  
Definition Of ◽  
Earth Dynamics

An ideal definition of a reference coordinate system should meet the following general requirements:1. It should be as conceptually simple as possible, so its philosophy is well understood by the users.2. It should imply as few physical assumptions as possible. Wherever they are necessary, such assumptions should be of a very general character and, in particular, they should not be dependent upon astronomical and geophysical detailed theories.3. It should suggest a materialization that is dynamically stable and is accessible to observations with the required accuracy.

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