Resolving the Circumstellar Environment of the Galactic B[e] Supergiant Star MWC 137 from Large to Small Scales

KRAUS, MICHAELA; CAPPA, CRISTINA E.; CIDALE, LYDIA S.; LIIMETS, TIINA; DURONEA, NICOLAS U.; ARIAS, MARIA L.; NICKELER, DIETER H.; FERNANDES, MARCELO BORGES; OKSALA, MARY E.; GUNAWAN, DIAH S.; SANTANDER-GARCÍA, MIGUEL; CURÉ, MICHEL; MARAVELIAS, GRIGORIS

The Astronomical Journal

The Astronomical Journal

Lugar: Londres; Año: 2017 vol. 154 p. 186 - 202

The Galactic object MWC 137 was suggested to belong to the group of B[e] supergiants. However, with its large-scaleoptical bipolar ring nebula and the high velocity jet and knots, it is a rather atypical representative of this class. Weperformed multi-wavelength observations spreading from the optical to the radio regime. Based on optical imagingand long-slit spectroscopic data we found that the northern parts of the large-scale nebula are predominantly blue-shifted, while the southern regions appear mostly red-shifted. We developed a geometrical model consisting of twodouble-cones. While various observational features can be approximated with such a scenario, the observed velocitypattern is more complex. We also resolved one of the knots in the jet, which appears to be split into at least twoprominent sub-components displaying a velocity dispersion with smaller velocities at larger distances. Using near-infrared integral-field unit spectroscopy we studied the hot molecular gas in the close vicinity of the star. The emissionfrom the hot CO gas arises in a small-scale disk revolving around the star on Keplerian orbits. While the disk itselfcannot be spatially resolved, its emission is reflected by dust arranged in arc-like structures and clumps surroundingMWC 137 on small scales. In the radio regime we mapped the cold molecular gas in the outskirts of the optical nebula.We found that large amounts of cool molecular gas and warm dust embrace the optical nebula in the east, south andwest. No cold gas or dust were detected in the north and north-western regions.