The possibilities of the classification of simulated observations in the GAIA photometric system are investigated. The data simulated by Barselona group [gaia.am.ub.es] from the BaSeL-2.2 and NextGen2 libraries of synthetic spectra are used. At first, the flux distribution curves of synthetic spectra for NextGen model atmospheres [ftp.hs.uni-hamburg.de] are compared with the observed flux distribution curves of stars of few spectral classes [Straižys V., Sviderskienė Z., 1972]. It was shown, that just the atmospheric models of hotter stars (Teff > 5000 °K) predict the observed energy distribution quite well. The observations in the GAIA photometric system simulated by Barcelona group are classified using the method of comparison of the color indices of standard and investigated stars. The observations of stars of two magnitudes (G=15 mag and G=18 mag) in the C1M photometric system are investigated in more detail. The analysis of the results shows that the classification is more definite when the bank of more solid standards is used. The errors of classification are smaller for the hotter (Teff > 10000 °K) and more luminous (G=15 mag) stars. The interstellar extinction AV is defined more precisely for hotter stars and the stars with larger AV value (3 ≤ AV ≤ 5). The computing time necessary to classify one star using the method of comparison of the color indices of standard and investigated stars is measured . The classification algorithm is written in PERL. The time... [to full text]

This paper presents the photometric luminosity classification of M dwarfs in Kaptyn’s Selected Area 124 (SA124). This project is part of an ongoing program at Ball State University to use R, I, and CaH photometry in an attempt to probe low luminosity star contributions to the luminosity function. Data is taken at the Southeastern Association for Research in Astronomy (SARA) telescope located at Kitt Peak, Arizona. With a limiting magnitude of R=15.0, we have observed ~75% of a full square degree in SA124 and have detected 19 M dwarf candidates, which are then confirmed using matched 2MASS J, H, and K magnitudes. We present the detections of 19 ±4.4 M dwarfs observed in SA124. The current estimates of our luminosity function are consistent with those previously determined for the galactic plane. / Department of Physics and Astronomy

Red dwarf stars are one proposed solution to the dark matter problem in the Milky Way Galaxy These cool, low luminosity stars are difficult to detect and segregate in surveys. This study utilizes photometric data obtained on the Kron-Cousins photometric system to develop criteria that classifies stars as red. Two of the color indices are then used to create a two-color diagram to allow separation of giant and dwarf stars. An algorithm based on calculated equations is provided to separate the giant and dwarf stars after detection. A third class of stars, subdwarfs, is addressed as a potential problem in future surveys. Some suggestions for detecting and removing these contaminating stars from the data are offered. Finally, a colormagnitude diagram is developed for red dwarf stars with KronCousins photometry. This curve allows for fairly accurate determination of photometric parallaxes for the red dwarf stars.An attempt was made to segregate the red dwarfs into velocity classes prior to calibrating the color-magnitude diagram. It was found that this approach offered no additional useful information. / Department of Physics and Astronomy

Starspots are not well understood for contact binary star systems. The following properties of spots were systematically investigated: temperature, radius, colatitude, and longitude. Spots were modeled on an AE Phe like contact binary system. The spots were changed in a systematic manner. The light curve phases of primary minimum and primary maximum were affected by these parameter changes in a systematic manner, as well as the secondary minimum and maximum. It will be shown that it is possible to use the shift in these phases to study starspots over time. This information can also be used to identify the presence of spots in binary star systems.Starspots on contact binary systems are not commonly found at a longitude near 180°. The results of this study show that starspots near 180° should be the easiest to detect using photometric techniques. This is the most significant result from this study. Either there is an unknown physical reason why contact binary stars do not have starspots near a longitude of 180°, or the starspots are there and the photometric data has been misinterpreted. / Department of Physics and Astronomy

Volume-limited samples indicate that red dwarfs are the most abundant stars in the Milky Way and account for most of its mass, despite their low individual masses. However, because of their low luminosity, they are extremely underdetected in magnitude-limited surveys. Complicating the task of identification is the fact that they have the same temperature as red giants and thus are in the same spectral class. We must therefore look for certain spectral features to differentiate between dwarfs and giants. Intermediate-to-broad-band photometry is one method that allows us to perform this task quantitatively. The 2MASS point source catalog contains data for -0.5 billion objects, including photometry in three broadband infrared filters. This paper discusses the manner in which these data can be analyzed to find red dwarfs and the success rate of such analysis. / Department of Physics and Astronomy

Mode of access: World Wide Web. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 180-192). / Electronic reproduction. / Also available by subscription via World Wide Web / xviii, 192 leaves, bound col. ill. 29 cm

Thesis (Ph.D.)--McMaster University (Canada), 1995. / Source: Dissertation Abstracts International, Volume: 57-03, Section: B, page: 1862. Adviser: W. E. Harris.

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (p. 157-165). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: D.E. Winget. Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph. D.)--University of Canterbury, 2001. / Typescript (photocopy). Includes bibliographical references (p. [215]-225). Also available via the World Wide Web.