Intrinsic luminosity

Fig. 3.3. Theoretical Hertzsprung-Russell diagram. The right-hand scale shows in absolute bolometric magnitude what the left-hand scale expresses as the logarithm of the intrinsic luminosity in units of the solar intrinsic luminosity (Lq = 4 x 10 erg s ). On the horizontal axis, the logarithm of the effective temperature, i.e. the temperature of the equivalent blackbody, is put into correspondence with the spectral type of the star, as determined by the observer. This temperature-luminosity diagram shows the lifelines of the stars as strands combed out like hair across the graph. With a suitable interpretation, i.e. viewed through the explanatory machinery of nuclear physics, it opens the way to an understanding of stellar evolution and its twin science of nucleosynthesis. (Courtesy of Andre Maeder and co-workers.)...

At first glance, the spectral properties, absolute magnitudes (intrinsic luminosities) and shapes of the light curves of the majority of type la supernovas (SNIa) are remarkably similar. Only a few rather subtle photometric and spectrometric differences can be discerned from one object to another. 

The surface distribution of M stars is studied by differentiating them according to whether they show a circumstellar dust shell (CS) or not. Analysis shows that galactic latitudinal and longitudinal distributions are not determined by spectral subclasses alone. The study also indicates that the M type stars with CS have higher intrinsic luminosities in the K band than those without CS. The M stars used in the study are obtained from the Two Micron Sky Survey catalogue (IRC) which is an unbiased sample with respect to the interstellar extinction. The CS feature is identified by the ratio of flux densities at 12 and 25 m in the IRAS point source catalog. 

The distrbution of SNe according to type (table 2).Only 34% (219/633) of thediscovered SNe have been classified. SNI (type I SN) outnumber the remaining objects in ratio 3 2.SNI/SNII in ratio 2 l.The observational result is biased by lower intrinsic luminosity and higher absorption present in SNII,besides the fact that these latter objects avoid elliptical and early spiral galaxies.Al 1 these effects must be taken into account in order to derive meaningful frequencies. 

The problem with Hubble s law was complicated out of all proportion by attempts to specify the observed redshifts of an increasing number of quasars by the same linear formula used for galactic redshifts. Some theoretical ideas to explain quasar redshifts within standard cosmology were reviewed by Segal et al. (1991), and shown to culminate in the theory of luminosity evolution of quasars, designed to force the definition of intrinsic luminosity as a function of distance. 

Because of the distance of the Clouds, and the intrinsic luminosity and spectrum of the objects, only few of the Catalogue sources can reasonably be expected to be the infrared counterpart of stellar, or semi-stellar objects. We have nevertheless performed a cross-correlation of the Catalogue with the following published catalogues of such objects ... 

Hubbard, W. B. (1980). Intrinsic luminosity of the Jovian planets. Review of Geophysics and Space Physics, 18(1), 1-9. 

The chemical analysis has revealed that rather low C/O ratios are found in metal-poor extragalactic carbon stars, as found for galactic carbon stars of the solar vicinity. Furthermore, the three analyzed stars show similar s-elements enhancements [ls/Fe]=0.8-1.3 and [hs/Fe]=l.l-1.7. This leads to new constraints for evolutionary models. For instance, the derived C/O and 13C/12C ratios are lower than model predictions at low metallicity. On the contrary, theoretical predictions of neutrons exposures for the production of the s-elements are compatible with observations (see Fig. 1). Finally, from their known distances, we have estimated the luminosities and masses of the three stars. It results that SMC-B30 and Sgr-C3 are most probably intrinsic carbon stars while Sgr-Cl could be extrinsic. 

Variable stars are so called because the luminosity of the star varies intrinsically and is not due to the passage of an eclipsing star. One such class of stars is the... 

The measured spectral resolution of the new grating micro-spectrofluorometer is about 1 nm and preliminary trials show that the luminosity is improved by at least ten-fold as compared to the older Ultropak-prism-microspectrofluorometer. The acquired increased sensitivity is best exploited using objectives and immersion oils of low intrinsic fluorescence. 

The basic data for stochastic simulations of galaxies and their constituent populations and metallicity evolution is the initial mass function (IMF), which represents the mass distribution with which stars are presumed to form. Its derivation from the observed distribution of luminosity among field stars (refs. 57 and 58 and references therein) and from star clusters involves many detailed corrections for both stellar evolution and abundance variations among the observed population. The methods for achieving the IMF from the observed distribution are most thoroughly outlined by Miller and Scalo but can be stated briefly, since they also relate to an accurate testing of various proposed stochastic methods. It should first be noted that the problems encountered for stellar distributions are quite similar to those with which studies of galaxies and thdr intrinsic properties have to deal. 

We present preliminary results on the intrinsic shapes of s[nral galaxy disks, based on a K -band imaging surrey. The sample galaxies were selected to be face-on on the basis of their HI linewidths and their luminosities. We fit two-dimensional bulge-disk modds that minimize the impact of spiral structure on the apparent shape. We find that for the majority of galaxies the intrinsic disk ellipticity at a few scale lengths is 0.35 and briefly discuss implications for the diape of the dark matter halos and for the intrinsic scatter in the TuUy-Fisher relation. 

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