English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We report long-baseline interferometric measurements of circumstellar dustaround massive evolved stars with the MIDI instrument on the Very LargeTelescope Interferometer and provide spectrally dispersed visibilities in the8-13 micron wavelength band. We also present diffraction-limited observationsat 10.7 micron on the Keck Telescope with baselines up to 8.7 m which explorelarger scale structure. We have resolved the dust shells around the late typeWC stars WR 106 and WR 95, and the enigmatic NaSt1 (formerly WR 122), suspectedto have recently evolved from a Luminous Blue Variable (LBV) stage. For AG Car,the protoypical LBV in our sample, we marginally resolve structure close to thestar, distinct from the well-studied detached nebula. The dust shells aroundthe two WC stars show fairly constant size in the 8-13 micron MIDI band, withgaussian half-widths of ~ 25 to 40 mas. The compact dust we detect around NaSt1and AG Car favors recent or ongoing dust formation.  Using the measured visibilities, we build spherically symmetric radiativetransfer models of the WC dust shells which enable detailed comparison withexisting SED-based models. Our results indicate that the inner radii of theshells are within a few tens of AU from the stars. In addition, our modelsfavor grain size distributions with large (~ 1 micron) dust grains. Thisproximity of the inner dust to the hot central star emphasizes the difficultyfaced by current theories in forming dust in the hostile environment around WRstars. Although we detect no direct evidence for binarity for these objects,dust production in a colliding-wind interface in a binary system is a feasiblemechanism in WR systems under these conditions.

Mid-Infrared interferometry of dust around massive evolved stars