Some observations of T Tauri stars for polarization effects.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Some observations of T Tauri stars for polarization effects. Weston, Edwin B. Abstract The pairs of photographic plates used in the measurement of the polarization of NGC 6729 (Whitney and Weston 1948) and NGC 7023 (Weston 1952) have been surveyed for stars exhibiting abnormal polarization and/or variability in brightness. Both regions contain variable and emission-line stars which are involved in diffuse nebulosity, and probably a large percentage of these stars belong to the T Tauri class. All of the exposures were made at the prime focus of the 8~-inch reflector of the McDonald Observatory and were of 120 min. duration on panchromatic plates behind Polaroid and aesculine filters, which eliminated the violet and ultraviolet light. The plates are well suited for comparison, and it is estimated that polarizations as small as 2 per cent could have been detected for stars with optimum orientation of the electric vector. No stars showed a difference in brightness on the pair of plates, taken on a single night, centered on NGC 6729; eleven stars showed a difference on the pair centered on NGC 7023, taken 22 days apart. These eleven stars in the region of NGC 7023 are variable in light, and there is no reason to believe they exhibited abnormal polarizations. The knot in NGC 6729 for which a large polarization was measured is not starlike. Polarization observations of the regions of NGC 7023, 2264, and other areas made with the Curtis telescope of the University of Michigan, although not as suitable for stellar photometry, do support the conclusions already reached. We may conclude that the large polarizations suggested for T Tauri stars either do not occur or are rare, measurable only in ultra-violet light, and are not of a permanent nature. Weston, E. B. 1952, A. J. 57, 28. Whitney, W. T. and Weston, E. B. 1948, Ap. J. 107, 371. A mherst College Observatory, Amherst, Mass., and Smith College Observatory, Northampton, Mass. Publication: The Astronomical Journal Pub Date: September 1958 DOI: 10.1086/107764 Bibcode: 1958AJ.....63..311W full text sources ADS | data products SIMBAD (1)