Stars Classification

Early astronomers also knew that stars seemed to have different colors, hut a system for classifying stars on the basis of color was not proposed until about 1872. That system was proposed hy the American astronomer Henry Draper (1836-82). Draper s system of classification was very important because a star s color is an indication of its second major property, its temperature. The hotter a star, the more likely its color is to be in the blue to white range. The cooler the star, the more likely it is to emit an orangish or reddish color. Draper died before he could complete his system of star classification. The project was completed between 1918 and 1924 by the American astronomer Annie Jump Cannon (1863-1941). 

Classical astronomy is largely concerned with the classification of stars without regard to the details of their constituent plasmas (63). Only more recently have sateUite-bome observations begun to yield detailed data from the high temperature regions of other stellar plasmas. Cosmic plasmas of diverse size scales have been discussed (64). 

The evidence on which this theory of stellar evolution is based comes not only from known nuclear reactions and the relativistic equivalence of mass and energy, but also from the spectroscopic analysis of the light reaching us from the stars. This leads to the spectral classification of stars, which is the cornerstone of modem experimental astrophysics. The spectroscopic analysis of starlight reveals much information about the... 

An important distinction for conjugated hydrocarbons is the classification into alternant and non-alternant hydrocarbons. Alternant hydrocarbons are those like ethene, hexatriene, benzene and naphthalene where we can divide the carbon atoms into two sets called starred and unstarred , such that no member of one set is directly bonded to another member (Figure 7.4). 

Now that we have a simple model for the continuum spectrum of the stars based around the Planck curve, the temperature and the luminosity, we can make some observations and classifications of the stars. There are some constellations that dominate the night sky in both the northern and southern hemispheres and even a casual look should inspire wonder. Star hopping in the night sky should lead to the simplest observation not all stars have the same colour. A high-quality photograph of the constellation of Orion (see page 2 of the colour plate section) shows stars... 

The three broad classifications (elliptical, spiral and irregular) of star clusters that also cluster together to form the Local Group that contains the Milky Way and the Andromeda Galaxy, along with the Small and Large Magellanic Clouds... 

The spectral features observed by astronomers have led to the classification of stars into seven broad classes outlined in Table 4.1, together with their surface temperatures. The highest-temperature class, class O, contains may ionised atoms in the spectrum whereas the older stars in class M have a much lower temperature and many more elements present in the spectrum of the star. Observation of a large number of the stars has lead to extensive stellar catalogues, recently extended by the increased sensitivity of the Hubble Space Telescope. Making sense of this vast quantity of information is difficult but in the early 19th century two astronomers... 

The four general types of stars (main sequence, white dwarfs, giants and supergiants) provide a classification based on the fundamental observable properties but also suggest an evolution of stars. Astrochemically, the cooler giants and supergiants have many more atomic and molecular species that are the products of the nuclear fusion processes responsible for powering the stars. The nuclear fusion processes allow for the formation of more of the elements in the Periodic Table, especially the heavier elements that dominate life on Earth - principally carbon. 

The A-B type iniferters are more useful than the B-B type for the more efficient synthesis of polymers with controlled structure The functionality of the iniferters can be controlled by changing the number of the A-B bond introduced into an iniferter molecule, for example, B-A-B as the bifunctional iniferter. Detailed classification and application of the iniferters having DC groups are summarized in Table 1. In Eqs. (9)—(11), 6 and 7 serve as the monofunctional iniferters, 9 and 10 as the monofunctional polymeric iniferters, and 8 and 11 as the bifunctional iniferters. Tetrafunctional and polyfunctional iniferters and gel-iniferters are used for the synthesis of star polymers, graft copolymers, and multiblock copolymers, respectively (see Sect. 5). When a polymer implying DC moieties in the main chain is used, a multifunctional polymeric iniferter can be prepared (Eqs. 15 and 16), which is further applied to the synthesis of multiblock copolymers. 

Bowker, Geoffrey C., and Susan Leigh Star. 1999. Sorting Things Out Classification and Its Consequences. Cambridge, Mass. MIT Press. 

Photoelectric or CCD photometry through colour filters is widely used for quantitative classification , i.e. to measure major spectral features with low wavelength resolution but rapidly and precisely to obtain major properties of large numbers of stars, such as... 

FIGURE 6.2 Representation of multivariate data by icons, faces, and music for human cluster analysis and classification in a demo example with mass spectra. Mass spectra have first been transformed by modulo-14 summation (see Section 7.4.4) and from the resulting 14 variables, 8 variables with maximum variance have been selected and scaled to integer values between 1 and 5. A, typical pattern for aromatic hydrocarbons B, typical pattern for alkanes C, typical pattern for alkenes 1 and 2, unknowns (2-methyl-heptane and meta-xylene). The 5x8 data matrix has been used to draw faces (by function faces in the R-library Tea-chingDemos ), segment icons (by R-function stars ), and to create small melodies (Varmuza 1986). Both unknowns can be easily assigned to the correct class by all three representations. 

Because of multiple receptor actions, which occur at different concentrations, different neuroleptics have different action profiles. There are many classifications for neuroleptic drugs, the least useful of which is probably based on their chemical structure. Other classifications include linear classifications based on the propensity to cause EPS, or multidimensional ones such as the Liege star which combines information on three positive effects (anti-autistic, antiproductive, antipsychotic), and three negative (hypotensive, extrapyramidal, sedative). In a general way, the more sedative neuroleptics such as levomepromazine, used more to treat acute agitation states, cause more hypotension related to alpha blockade, whereas those that act best on delirium (productive states) such as haloperidol tend to cause more EPS. 

There are several bodies of information that feed into our understanding of stellar nucleosynthesis. We will start with a discussion of the classification of stars, their masses and mass distributions, and their lifetimes. From this information we can assess the relative importance of different types of stars to the nucleosynthesis of the elements in our solar system and in the galaxy. We will then discuss the life cycles of stars to give a framework for the discussion of nucleosynthesis processes. Next, we will review the nuclear pathways... 

In the MK system, most J-type stars are classified as C4-5 4-5 stars which show very strong C and CN bands. Yamashita(l972,l975) classified many C7-9 stars most of which are CS or SC stars. His classification of C7-9J stars is mainly based on Cl2Cl3(0,l)band at 6168 A, C13N(4,0)band at 6260 A, and Lil 6708 A line. In most of C7-9 stars, lines of s-process elements are greatly enhanced. It is a question if in all J-type stars abundances of s-process elements are nearly normal or not. 

We tested the classification of J-type stars using the spectra obtained at the Okayama Astrophysical Observatory, in the region between 4400 A and 6800 A with a... 

We have been making survey observations of faint cool carbon stars using the Kiso 105-cm Schmidt telescope. Kodak IN and 103aF plates are respectively taken behind the 4-degree objective prism (700 Amm-1 at Ha) for the detection and for the spectral classification. F-band plates are utilized to obtain the position and... 

Bright carbon stars in the Cassiopeia region are classified into the C classification system (Yamashita 1972, 1975) using 103aF plates (AA4500 - 6800 A). Six criteria are extracted from spectral tracings of standard stars. Fifty nine... 

The space distribution in the Cassiopeia region is estimated on the basis of the spectral classification and the absolute magnitudes determined by Mikami (1975). It is shown that the carbon stars are distributed over the galactic plane without strong concentration onto the (Perseus) arm. The number ratio of C4 - C5, C6 -C7, and C8 - C9 stars is nearly 1 0.4 < 0.1. 

The Wolf-Rayet classification is a one-dimensional system. However, as outlined in Sect. 4, their spectra depend on two parameters. Therefore, a two-dimensional classification clearly has to be introduced, e.g. as already suggested by Hiltner and Schild (1966) and refined by Walborn (1974). For later use in this paper, we divide the Wolf-Rayet stars into four classes ... 

The results are summarized in Figure 1. The different symbols denote the spectral classification of the individual stars, whereas four groups are distinguished WNE-A, WNE-B, WNL and WC stars. The size of the symbols indicates the mass-loss rates. The uncertainties of the results are estimated to be 0.1 dex in T, 0.4 dex in M and 0.5 dex in L. For the 11 stars in common with the sample of Abbott et al. (1986) we find our mass-loss rates to be compatible with their radio flux if the correct ionization equilibrium in the radio emitting region is applied (Schmutz and Hamann, 1986). The model calculations show that for all but the WN2 and WN3 stars helium recombines to He before the ions enter the radio-emitting region. 

Since the appearance of the 6-th WR Catalog (van der Hucht et ai. 1981) the galactic distribution of WR stars has been studied by many authors (Hidayat et al. 1981. 1984 Meylan and Maeder. 1983 Conti et al. 1983). Recently the membership of 42 WR stars in open clusters and associations has been reassessed (Lundstrom and Stenholm, 1984) and improved photometry (Massey. 1984) and new classifications have become available for a considerable fraction of the 157 known galactic WR stars. This allows a redetermination of the intrinsic parameters (b-v)Q and My of WR stars and their photometric distances. 

Fig. 1 allows only WC4-7->WO evolution. In view of the alternative WC4-5p classification of the WO stars, a WC4-5->WO trail is clearly more probable. 

Fig. 2 Classification of star-shaped three arm mesogens. Flexible (subgroup (i)), semi-flexible (subgroup (ii)) and shape-persistent (subgroup (Hi)) star-shaped molecules. Folding of star-shaped semi-flexible molecules to X- and -shaped mesogens [2], Copyright Wiley-VCH Verlag GmbH Co. KGaA. Reproduced with permission...

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