Thomas A. Pauls

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We report the successful fitting of a Roche model, with a surface temperature gradient following the von Zeipel gravity darkening law, to observations of Altair made with the Navy PrototypeOptical Interferometer.We confirm the claim by Ohishi et al. that Altair displays an asymmetric intensity distribution due to rotation, the first such detection in an(More)
Vega, the second brightest star in the northern hemisphere, serves as a primary spectral type standard. Although its spectrum is dominated by broad hydrogen lines, the narrower lines of the heavy elements suggested slow to moderate rotation, giving confidence that the ground-based calibration of its visible spectrum could be safely extrapolated into the(More)
Interferometric observations of two well-known Be stars, Cas and Per, were collected and analyzed to determine the spatial characteristics of their circumstellar regions. The observations were obtained using the Navy Prototype Optical Interferometer equipped with custom-made narrowband filters. The filters isolate the H emission line from the nearby(More)
We have developed a method for performing long coherent integrations with the Navy Prototype Optical Interferometer (NPOI), which is based on fitting a model fringe pattern to the NPOI data frames. The procedure is quite computationally intensive, but gives a better estimation of the phase than the conventional method of location the peak of the group delay(More)
Interferometric observations of two well-known Be stars, γ Cas and φ Per, were collected and analyzed to determine the spatial characteristics of their circumstellar regions. The observations were obtained using the Navy Prototype Optical Interferometer equipped with custom-made narrowband filters. The filters isolate the Hα emission line from the nearby(More)
In this paper we use coherently integrated visibilities (see separate paper in these proceedings) to measure the properties of binary stars. We use only the phase of the complex visibility and not the amplitude. The reason for this is that amplitudes suffer from the calibration effect (the same for coherent and incoherent averages) and thus effectively(More)
The discovery that Vega is a rapidly rotating pole-on star has raised a number of questions about this fundamental standard, including such issues as its composition, and in turn its mass and age. We report here a reanalysis of Vega’s composition. A full spectral synthesis based on the Roche model derived earlier from NPOI interferometry is used. We find(More)
We present optical interferometric observations of the Be star Tauri obtained using the Navy Prototype Optical Interferometer (NPOI). The multichannel capability of the NPOI allows a high-quality internal calibration of the squared visibilities corresponding to the H emission from the circumstellar environment. The observations suggest a strong departure(More)