VizieR Online Data Catalog: VLT/SPHERE Y-band images of MWC 758 at two epochs (Ren+, 2020)
Résumé
More than a dozen young stars host spiral arms in their surrounding protoplanetary disks. The excitation
mechanisms of such arms are under debate. The two leading hypotheses – companion-disk interaction and
gravitational instability (GI) – predict distinct motion for spirals. By imaging the MWC 758 spiral arm system
at two epochs spanning ∼5 yr using the SPHERE instrument on the Very Large Telescope (VLT), we test the
two hypotheses for the first time. We find that the pattern speeds of the spirals are not consistent with the GI
origin. Our measurements further evince the existence of a faint “missing planet” driving the disk arms. The
average spiral pattern speed is 0.◦22 ± 0.◦03 yr−1, pointing to a driver at 172+18
−14 au around a 1.9 M central
star if it is on a circular orbit. In addition, we witness time varying shadowing effects on a global scale that are
likely originated from an inner disk
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