Very long baseline interferometric observations of the H20 sources inW49N, W3(OH), ORI A, and VY CMa.

Abstract

view Abstract Citations (94) References (79) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Very long baseline interferometric observations of the H2O sources in W49N, W3(OH), Orion A, and VY Canis Majoris. Moran, J. M. ; Papadopoulos, G. D. ; Burke, B. F. ; Lo, K. Y. ; Schwartz, P. R. ; Thacker, D. L. ; Johnston, K. J. ; Knowles, S. H. ; Reisz, A. C. ; Shapiro, I. I. Abstract Observations of four galactic H20 sources were made in 1970 June and 1971 February and March at 1.35-cm wavelength with interferometers having fringe spacings between 00008 and 001. The features in the spectrum of W49 N between -16 and + 12 km -1 were all unresolved and apparently smaller than 0.0005 (1.1 x 1014 cm) in diameter (uniform disk model). The feature at -1.8 km 1 was less than 0.0003 (0.7 x 1014 cm) in diameter. The features were distributed over an area of about 1" >c 1" (2 x 2 x 1017 cm) and clumped into three regions. Differences in the spatial distribution were observed among the three measurement periods. The H20 emission regions were coincident, within 5", with the OH emission source. The five features in the spectrum of W3(OH) between -52 and -47 km s - were all unresolved, with upper limits of 0'!002 (0.7 x 1014 cm) in diameter. The emission region had dimensions 2" >c 0"2 (0.8 x 0.08 >c 1017 cm). The features in the Ori A source had apparent sizes between 00008 (0.6 x 1014 cm) and 001 (8 x 1014 cm) and were spread over an area of 30" >c 30" (2 x 2 >c 1017 cm). Changes in the spatial distribution occurred between observations. The two strongest features in VY CMa were unresolved and smaller than 0'.'002 (3 x 1013 cm) and were separated by 015 (0.2 x 1016 cm). The emission region in VY CMa was an order of magnitude smaller in linear dimension than were those of the other three sources and probably has significantly different physical conditions. Some of the interferometric spectra of W49 N and Ori A seem consistent with the presence of hyperfine structure. Subject headings: molecules nebulae - radio sources Publication: The Astrophysical Journal Pub Date: October 1973 DOI: 10.1086/152437 Bibcode: 1973ApJ...185..535M full text sources ADS | data products SIMBAD (5)