The space density distribution of late-type giants in the solar neighbourhood

1982 ◽  
Vol 87 (1-2) ◽  
pp. 247-254
Author(s):  
S. K. Ghosh ◽  
S. N. Tandon
Keyword(s):  
Density Distribution ◽  
Solar Neighbourhood ◽  
Late Type ◽  
Space Density

scholarly journals Constraints for Cataclysmic Binary Evolution as Derived from Space Distributions

1984 ◽  
Vol 80 ◽  
pp. 363-385
Author(s):  
H. W. Duerbeck
Keyword(s):  
Stellar Populations ◽  
Recurrence Time ◽  
Type I ◽  
Symbiotic Stars ◽  
Late Type ◽  
Dwarf Novae ◽  
Space Density ◽  
Long Period ◽  
Mira Variables ◽  
Cataclysmic Binaries

AbstractSpace densities and galactic z-distributions of novae, recurrent novae, dwarf novae and symbiotic stars are newly determined and discussed in the context of earlier determinations. The data are then compared with the distributions of single and binary stars of possibly related types (late type giants, Mira variables, Algol systems, W UMa systems).Novae and dwarf novae have similar distributions, those of fairly young stellar populations. The observed space density of potential novae (novalike objects) indicates that the mean recurrence time of novae might be as small as a few hundred years, which leads, with given nova shell masses and mass transfer rates in the minimum stage, to a secular decrease of the masses of the components undergoing nova outbursts.Recurrent novae and symbiotic stars have distributions of older stellar populations, similar to those of late type giants and Mira variables.On the basis of galactic distribution, novae and dwarf novae are closely related and may be final stages of W UMa systems, as well as progenitors of supernovae of type I. A small fraction of W UMa systems seems to belong to an older population. If evolutionary transitions between these types of stars can be substantiated, the presence of a minority of novae and dwarf novae in globular clusters and of supernovae I in elliptical galaxies can be explained.Due to the lack of sufficiently well determined space distributions of Algol binaries, the suggestion that long-period Algol systems might be the progenitors of cataclysmic binaries can as yet neither be substantiated nor refuted. A very high space density of long-period Algol systems in the solar neighbourhood is derived. The observed space density of cataclysmic binaries could be explained by the transformation of a small percentage of the long-period Algol systems by common envelope evolution.

Preliminary study on space density distribution of intense electron beam in foilless diode

2014 ◽  
Vol 26 (4) ◽  
pp. 43006
Author(s):  
霍少飞 Huo Shaofei ◽  
孙钧 Sun Jun ◽  
陈昌华 Chen Changhua ◽  
梁玉钦 Liang Yuqin ◽  
吴平 Wu Ping ◽  
...  
Keyword(s):  
Electron Beam ◽  
Density Distribution ◽  
Space Density ◽  
Intense Electron Beam ◽  
Preliminary Study ◽  
Intense Electron

scholarly journals The Stellar Content of the Nuclei of Spiral Galaxies

1983 ◽  
Vol 6 ◽  
pp. 157-163
Author(s):  
D. Crampton ◽  
R.D. McClure ◽  
A.P. Cowley
Keyword(s):  
Spectral Type ◽  
Stellar Population ◽  
Main Sequence ◽  
Spiral Galaxies ◽  
Elliptical Galaxies ◽  
Solar Neighbourhood ◽  
Stellar Content ◽  
Late Type ◽  
Metal Abundances ◽  
Hydrogen Lines

Numerous studies have been attempted to determine the stellar content of the nuclei of galaxies. In the case of elliptical galaxies observations show that there is a change in spectral type from later to earlier types correlated with a variation from high to low luminosity (e.g. Faber 1977). This has been interpreted for the most part as being due to differences in metal abundances in an old stellar population, although some recent studies suggest a variation in stellar age may be important as well (e.g. O’Connell 1980, Heckman 1980). The nuclear bulges of spiral galaxies also display a change from late to early spectral type along a sequence from high to low luminosity bulges. In this case, however, the assumption has almost universally been made that these differences are due to differences in age of the stellar population. In particular, most stellar models for the nuclear bulges of spiral galaxies have used solar neighbourhood metal- rich stars, and assumed that the strong hydrogen lines and weak metal lines in late-type spiral nuclei are due to the predominance of a very young main-sequence population rather than old metal-poor stars.

scholarly journals The Stellar Space Distributions of dA and gK Stars

1995 ◽  
Vol 148 ◽  
pp. 271-275
Author(s):  
D. N. Dawanas ◽  
B. Hidayat
Keyword(s):  
Density Distribution ◽  
Relative Density ◽  
Galactic Plane ◽  
Space Distribution ◽  
Space Density ◽  
Density Distributions ◽  
The Galaxy ◽  
The Matrix ◽  
Space Volume

AbstractWe present a case study on the stellar space distribution of stars with MK spectral types B8 to A2 (dA) and gG8 to gK2 (gK) in a sky region of 25 square degrees, centred at the galactic coordinate l = 4° and b = +12°. Two hundred and forty-eight (248) stars with MK type of B8–A2 and gG8–gK2 were identified in this field. The space density distributions of these stars were obtained by employing the Matrix and Malmquist methods. The relative density of B8–A2 stars tends to be similar to that of gG8–gK2 stars, which implies that the two groups of stars occupy the same space volume in the galaxy. The comparison with those of Field-3 (l = 0.8°, b = –10°) show that the space density distribution of the two groups of stars above and below the galactic plane is not the same. Above the galactic plane, the space density of the gK stars is higher than those of dA stars, whereas below the galactic plane the density of dA stars is higher than for the gK stars. For both groups, the maximum space density occurs at around 30–40 pc from the galactic plane.

scholarly journals The Shape of the Luminosity Profiles of Bulges

1996 ◽  
Vol 157 ◽  
pp. 86-87 ◽  
Author(s):  
Y. Andredakis ◽  
R. Peletier ◽  
M. Balcells
Keyword(s):  
Density Distribution ◽  
Decomposition Method ◽  
Surface Brightness ◽  
A Priori ◽  
Morphological Type ◽  
Early Type ◽  
Late Type ◽  
Dimensional Decomposition ◽  
The Galaxy ◽  
Light Profiles

AbstractWe extract the bulge light profiles of a sample of early type spirals, using K-band photometry and a new 2-dimensional decomposition method that does not assume a priori any surface brightness laws. We find that the shape of the light profile shows a good correlation with the morphological type of the galaxy, in the sense that the profiles tend to fall off more steeply at large radii for the later types. This trend shows that the formation of or interaction with the disk has probably affected the density distribution of the bulge. The fact that the transition in shape is continuous might also imply that most of the bulges of late type spirals were not formed by different mechanisms than the ones of early types.

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