Massive Variability Searches: The Past, Present and Future Massive Variability Searches

Many decades ago a search for variable stars was one of the main areas of astrophysical research. Such searches, conducted with CCD detectors rather than with photographic plates, became a by-product of several projects seeking gravitational microlensing events towards the Magellanic Clouds and/or the Galactic Bulge: EROS, MACHO, and OGLE. These searches demonstrated that is is possible and practical to process in near real time photometry of tens of millions of stars every night, and to discover hundreds of thousands of variable stars. A limited subset of new variable star catalogs was published, but no comprehensive database of all photometric results became public domain so far. In the last few years a much broader, but shallower searches have been undertaken, and many other are at various stages of implementation or planning. There is a need to develop a system that would allow all these data to be processed and to be posted on the Internet in real time. Full information related to variability of point sources is made of a relatively few data types, hence it may be relatively easy to handle. Yet, it may be diverse enough to be interesting to a large number of users, professional as well as amateur, making it possible to do real time virtual observing, as well as data mining.Comment: Published in the Proceedings of the MPA/ESO/MPE Workshop: `Mining the Sky' held at Garching, Germany July 31 - August 4, 2000; Springer, Eds: A.J. Banday, S. Zaroubi, and M. Bartelmann, p. 481; latex, 6 page

The Distance to Pleiades

The distance to Pleiades remains controversial. There is a simple way to resolve the dispute definitely by measuring the distance to one of its brightest members, Atlas, which is astrometric and spectroscopic binary.Comment: 3 pages, latex, 1 figure, submitted to Acta Astronomic

Metallicity of Red Clump Giants in Baade's Window

The red clump giants are potentially very useful as standard candles. There is some controversy about the stability of their I-band absolute magnitude, but it does not seem to be serious. No controversy was anticipated about their colors, with metal rich giants expected to be redder and cooler than the metal poor giants. The purpose of this paper is to point out that no such correlation is apparent between [Fe/H] and effective temperature as determined with Washington CCD photometry for the giants in Baade's Window. No explanation is offered for this surprising result. It is also unknown why the galactic bulge red clump giants are redder than the clump giants near the Sun by 0.2 mag in the (V-I) color.Comment: 8 pages, self-contained latex, 5 postscript figures, submitted to Acta Astronomic

Current Status of the Microlensing Surveys

The ongoing microlensing searches have generated more photometric measurements of pulsating stars than all previous observing projects combined. In particular, OGLE has made ~ 340,000 B, V, and I-band measurements of ~ 1,300 Cepheids in the Large Magellanic Clouds accessible over Internet. Microlensing searches contributed to the development of very efficient image subtraction software which works best in crowded fields. This suggests the use of a period - flux amplitude rather than period - luminosity relation for the Cepheids for distance determination, as the flux amplitude is directly measurable with the image subtraction, and it is not biased by crowding. Future projects will dramatically increase the data rate, will provide all-sky coverage and a complete census of variables, including pulsating stars, to the ever fainter limits. Time will show which approach, a small number of large teams or a large number of small teams, will be more productive.Comment: 9 pages with 3 figures, latex, revised and extended on November 29, 1999, to be published in the ASP Conference Series Vol. XXX, 1999: ``The Impact of Large Scale Surveys on Pulsating Star Research'', L. Szabados and D. Kurtz, ed

To the concept of the elastic interaction

A general description of elastic matter and the long-range elastic interaction is propose. The type of the far-field interaction is determined by the way of breaking in the continuum distribution of the elastic field produced by topological defects, which can present isolated inclusions. To provide an adequate description of the inter-inclusion interaction. Thus we can determine the size of inclusion as core topological defect in elastic field. In this description the charge in electrodynamic and mass in gravity present peculiarity of elastic filed and determined in term this field. The interaction is a direct and immediate result of the field deformation. Exist two type interaction. Interaction through change the ground state of elastic matter and interaction with the help of the carrier of interaction, which can present as small changing of deformations.Comment: 5 page

Gravitational Microlensing by the Globular Cluster Stars

The microlensing of background stars by compact objects in globular clusters is analyzed. The main strength of the proposed search is the direct relationship between the lens mass and the time scale of the microlensing event. The main problem is the low overall rate of expected events which implies that a ground based search should last for about a decade to generate a non trivial number of events, like a few dozen. A space borne experiment could increase the rate by a large factor by increasing the number of stars which could be monitored thanks to the much better seeing. The clusters M22 with the galactic bulge background, and 47 Tuc with the SMC background, are the two examples of possible targets.Comment: 6 pages; plain TeX. Accepted for publication in Acta Astronomica 44/

Four-Fermi Effective Operators at e^+ e^- ---> \bar{t} t

The process of top quark pair production at Next Linear Collider (NLC) has been considered adopting an effective Lagrangian approach and including all operators of dim~6 which can be tree-level-generated within unknown underlying theory. All contributing helicity amplitudes are presented. It has been found that four-fermion operators can provide the leading non-standard contribution to the total cross section. Expected statistical significance of the non-standard signal for the total cross section and forward-backward asymmetry have been calculated taking into account existing experimental constraints. It has been shown that adopting realistic luminosity of NLC and conservative efficiency for the top-quark pair detection, the total cross section may be sensitive to non-standard physics of an energy scale around \Lambda=5\tev.Comment: LaTex, 10 pages, 4 PostScript figures (uuencoded

Cellular structure in system of interacting particles

The general description of formation the cellular structure in the system of interacting particles is proposed. Interactions between particles are presumably well-understood and the phase transition in which can be studied in the scale of particle resolution. We presented analytical results of possible cellular structures for suspension of colloidal particles, in system particles immersed in liquid crystal and gravitational system. We have shown that cellular structure formation can occur in system of interacting particles for realistic values of temperature and particles concentration.Comment: 5 page

Genetic Optimization of Keywords Subset in the Classification Analysis of Texts Authorship

The genetic selection of keywords set, the text frequencies of which are considered as attributes in text classification analysis, has been analyzed. The genetic optimization was performed on a set of words, which is the fraction of the frequency dictionary with given frequency limits. The frequency dictionary was formed on the basis of analyzed text array of texts of English fiction. As the fitness function which is minimized by the genetic algorithm, the error of nearest k neighbors classifier was used. The obtained results show high precision and recall of texts classification by authorship categories on the basis of attributes of keywords set which were selected by the genetic algorithm from the frequency dictionary

On the Detectability of Very Massive Compact Objects with Gravitational Microlensing

If the dark halo of our galaxy is made of compact objects as massive as M = 10^6 solar masses, their detection by means of ordinary microlensing searches would take a very long time as the characteristic time scale of such a lensing event, t_0, is approximately 200 years. Fortunately, the very high magnification events of the numerous faint stars, which are normally well below the detection threshold, have short duration peaks with a characteristic time scale of only t_0 / A_{max}, where A_{max} >> 1 is the peak magnification factor. The two almost equally bright images are separated by approximately 2'' (M/10^6 solar masses )^{1/2}, and they rotate very rapidly around the lens with the relative proper motion enhanced by a factor 2 A_{max}. The same events will offer an opportunity to study spectroscopically stars which are normally far too faint to be reached.Comment: 6 pages, plain TEX, no figure