New population synthesis models, with the effects of metallicity spread and the horizontal-branch (HB) morphology, provide a way to break the well-known age-metallicity degeneracy in the analysis of the integrated light of elliptical galaxies. Our models suggest that the far- UV radiation of these systems is dominated by a minority population of metal-poor, hot HB stars and their post-HB progeny, while the optical radiation is dominated by a metal-rich population. The systematic variation of UV upturn depends on the contribution from metal-poor, hot HB stars and their post-HB progeny, which in turn depends on the ages of old stellar populations in galaxies. Our result implies a prolonged epoch of galaxy formation, in the sense that more massive galaxies (in denser environments) formed first. Our models also suggest that the strenghth of Hβ index is strongly affected by HB stars, and hence previous age estimation without detailed modeling of the HB would underestimate the ages of ellipticals by ~7 Gyr.

We have examined the photometric evolution of elliptical galaxies, using stellar evolutionary models covering the wide ranges of metallicity and mass, and the different IMFs (simple IMP & time-dependent bimodal IMF). The model with a time-dependent bimodal IMF can reproduce the observed integrated magnitudes and colors at all wavelengths. The computed model shows that the star formation in elliptical galaxies is still going on, although the number of newly born stars is very small. The chemical evolutionary effect is clearly seen in the C-M diagram of computed elliptical galaxies.

We review recent systematic investigation of the X-ray spectra of early type galaxies by using the Einstein data base and present new results by the ROSAT observations. The Einstein data suggested that the galaxies with low X-ray to optical luminosity ratio may have another very soft component. ROSAT observations confirm its presence and call for further study to understand the nature of this very soft emission. The X-ray bright galaxies have emission temperature of ∼0.8keV ∼0.8keV and show radial gradients in the sense that X-ray emission is softer and more absorbed in the inner region.

Being a rare form of sentence formation, not many languages seem to have Tag question constructions as English does (Culicover 1992:193). Besides, Cuenca (1997:4) notes that the English Tag question construction has received less and less attention in the later period of generative syntax, due to the colloquial characteristics of the construction. Of the two major distinct approaches to English Tag question constructions including Mono-clausal approaches such as Klima (1964), Arbini (1969), and den Dikkien (1995), and bi-clausal approaches such as Huddleston (1969), Culicover (1992), McCawley (1998), and Sailor (2009), the current paper proposes a Minimalist approach to Tag Question Construction using a series of Head movement, Focalization of vP, a Polarity reversing functional projection, PolP, which contains an abstract morpheme [NEG], and adjunction mechanism. Through these thorough and meticulous steps, the English Tag question construction receives a Minimalist facelift.

In this study, the time-area curve for an elliptical shaped basin was analytically derived. The assumptions introduced to derive the time-area curve are as follows. First, an infinite number of raindrops reach the impervious surface of the elliptical shaped basin evenly in space. Second, the vertical axis of the ellipse is assumed to be the channel of the elliptical shaped basin. Third, the direction of the surface runoff is always perpendicular to the channel flow. Fourth, the flow velocity remains the same in any location within each channel and land surface, the ratio of their flow velocity is consistent everywhere within the basin. As a result, the time-area curve for the basin can be derived with the equivalent ellipse of the basin along with the proper characteristic velocity within each channel and land surface. Furthermore, by multiplying the flow velocity with this time-area curve, one can derive the inflow to the linear reservoir, of which the outflow becomes the Clark IUH.

This paper intends to highlight the effect of the third-body in an inclined orbit on a spacecraft orbiting the primary mass. To achieve this goal, a new origin of coordinate is introduced in the primary and the X-axis toward the node of the spacecraft. The disturbing function is expanded up to the second order using Legendre polynomials. A double-averaged analytical model is exploited to produce the evolutions of mean orbital elements as smooth curves.