Dynamical Evidence of a Spiral Arm-driving Planet in the MWC 758 Protoplanetary Disk
Abstract
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, 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 ${172}_{-14}^{+18}$ 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 originating from an inner disk.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2020
- DOI:
- arXiv:
- arXiv:2007.04980
- Bibcode:
- 2020ApJ...898L..38R
- Keywords:
-
- Protoplanetary disks;
- Coronagraphic imaging;
- Planetary system formation;
- Orbital motion;
- 1300;
- 313;
- 1257;
- 1179;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 9 pages, 3 figures, published in ApJ Letters. Data files and gif movie of Figure 1ab in ancillary folder