Browsing by Author "Vogt, Nikolaus"
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- ItemA Novel Growth Mode of Alkane Films on a Sio2 Surface(2003) Mo, H.; Vogt, Nikolaus
- ItemA Search for Rapid Photometric Variations in Southern Be and Bn Stars(1991) Barrera S., Luis.; Vogt, Nikolaus
- ItemAn astrometric catalogue of southern and equatorial dwarf novae(1992) Vogt, Nikolaus
- ItemAtomic Force Microscopy Measurements of Topography and Friction on Dotriacontane Films Adsorbed on a Sio2 Surface(2005) Trogisch, S.; Vogt, Nikolaus
- ItemCorrelation and variability of the HeI 4471 and MgII 4481 absorption lines in Be stars: A possible diagnostic tool for nonradial pulsations(1990) Vogt, Nikolaus; Barrera, Luis H.; Navarro, MarioIn a total of 181 photographic spectrograms, obtained at the Manuel Foster Observatory of the Catholic University in Santiago (Chile), the equivalent widths of the absorption lines HeI 4471 and MgII 4481 have been determined for 10 selected southern Be stars and 4 normal B-type stars. The mean equivalent widths of each star are compared to published mean values from largers samples of B stars. On the average, Be stars coincide with normal B-type stars in their equivalent width. However, a striking difference between rapidly and slowly rotating stars in their line ratios (HeI/MgII) was found, which is probably an artifact due to a systematic misclassification of spectral types of rapidly rotating B stars (v sini>200 km s?1). Six of the ten Be stars show evidence for variability in HeI and/or MgII with time-scales shorter than a few days and amplitudes up to a factor 2 in equivalent width. Line variability occurs in the entire range of projected rotation velocity (70 km s?1
- ItemEvidence for Hibernation From a Statistical Analysis of Nova Eruption Amplitudes(1990) Vogt, Nikolaus
- ItemHidden Spectra Treasures in the Foster Archive: A Pilot Study of the Be Stars a Eri, a Col, ? Car and ? Cen(2022) Arcos, Catalina; Vanzi, Leonardo; Vogt, Nikolaus; Garcia, Stefano; Ortiz, Virginia; Acuna, EsterWe present the archive of spectroscopic photographic plates of the Universidad Catolica historic observatory Manuel Foster. The archive includes more than 4800 plates covering the period of time from 1928 to 1991. The spectra present in the archive are mostly those of bright variable or binary stars observed at different epochs. We developed a method of digitalization and data processing for the plates and verified it through the analysis of a selected sample of spectra. As an example of the potential relevance of this Foster archive we studied the variation of helium, H beta and H gamma spectral lines over time (1980-1991), complementing with high resolution spectroscopic data from the "Be Star Observation Survey " (2012-2015), of four Be stars mainly, alpha Eri, alpha Col, omega Car and eta Cen. The spectra of these stars show evidence of a circumstellar gas disk present in both periods of time. From the spectroscopic analysis, we found these stars are variable in helium and this variability presents an opposite behavior with the variability observed in the EW of the H beta line profile. This archive represents a unique source of data from past that is available for the use of the community.
- ItemNanoscale observation of delayering in alkane films(2007) Bai, M.; Vogt, Nikolaus
- ItemThe Photometric Period of the Recurrent Nova T Pyxidis(1992) Vogt, Nikolaus
- ItemThe photometric variations of the Ap star HD34631(1991) Vogt, Nikolaus
- ItemV/R Variations in H B Emision Profiles of Be Stars(1991) Vogt, Nikolaus