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The vicinity of the galactic supergiant B[e] star CPD -57 2874 from near- and mid-IR long baseline spectro-interferometry with the VLTI (AMBER and MIDI)

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Anatoly S. Miroshnichenko, Associate Professor (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: We present the first spectro-interferometric observations of the circumstellar envelope (CSE) of a B[e] supergiant (CPD -57' 2874), performed with the Very Large Telescope Interferometer (VLTI) using the beam-combiner instruments AMBER (near-IR interferometry with three 8.3 m Unit Telescopes or UTs) and MIDI (mid-IR interferometry with two UTs). Our observations of the CSE are well fitted by an elliptical Gaussian model with FWHM diameters varying linearly with wavelength. Typical diameters measured are ^ 1 .8 x 3 .4 mas or ^ 4. 5 x 8 . 5 AU (adopting a distance of 2 . 5 kpc) at 2. 2 µm, and ^ 12 x 15 mas or ^ 30 x 38 AU at 12 µm. We show that a spherical dust model reproduces the SED but it underestimates the MIDI visibilities, suggesting that a dense equatorial disk is required to account for the compact dust-emitting region observed. Moreover, the derived major-axis position angle in the mid-IR ( ^ 144° ) agrees well with previous polarimetric data, hinting that the hot-dust emission originates in a disk-like structure. Our results support the non-spherical CSE paradigm for B [e] supergiants.

Additional Information

Publication
http://arxiv.org/abs/astro-ph/0510736v1 26 Oct 2005
Language: English
Date: 2005
Keywords
Galactic supergiant B[e] star CPD -57 2874, Very Large Telescope Interferometer (VLTI), AMBER, MIDI