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Paper: Coordinated Science with the VLBA and the VLTI
Volume: 395, Frontiers of Astrophysics: A Celebration of NRAO's 50th Anniversary
Page: 361
Authors: Boboltz, D.A.; Wittkowski, M.
Abstract: We present an overview of a program currently underway to study Asymptotic Giant Branch (AGB) stars using polychromatic imaging with the VLBA and the Very Large Telescope Interferometer (VLTI). These two high-esolution instruments allow us to probe the star and its surrounding environment at unprecedented accuracy from centimeter to near-infrared wavelengths. The regions which we are able to study, working outward from the star itself, include: the photosphere (VLTI/AMBER, near-IR), the molecular layer (VLTI/MIDI, mid-IR), the SiO maser shell (VLBA/SiO, 7mm), the dust shell (VLTI/MIDI, mid-IR), and the circumstellar wind region (VLBA/H2O, 1.3cm). Thus far, we have coordinated observations of three Mira variables—S Ori, RR Aql, and GX Mon—and one supergiant star, AH Sco. Since these stars are inherently variable, it is important to get concurrent observations over multiple epochs in order to study both intra- and inter-cycle changes in the various regions of the circumstellar envelope.
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