astro-ph.EP

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# Title: A Decade of MWC 758 Disk Images: Where Are the Spiral-Arm-Driving Planets?

Abstract: Large-scale spiral arms have been revealed in scattered light images of a few protoplanetary disks. Theoretical models suggest that such arms may be driven by and co-rotate with giant planets, which has called for remarkable observational efforts to look for them. By examining the rotation of the spiral arms for the MWC 758 system over a 10-yr timescale, we are able to provide dynamical constraints on the locations of their perturbers. We present reprocessed {\it Hubble Space Telescope} ({\it HST})/NICMOS F110W observations of the target in 2005, and the new {\it Keck}/NIRC2 $L'$-band observations in 2017. MWC~758's two well-known spiral arms are revealed in the NICMOS archive at the earliest observational epoch. With additional {\it Very Large Telescope} ({\it VLT})/SPHERE data, our joint analysis leads to a pattern speed of ${0.6^\circ}^{+3.3^\circ}_{-0.6^\circ}\, \mathrm{yr}^{-1}$ at $3\sigma$ for the two major spiral arms. If the two arms are induced by a perturber on a near-circular orbit, its best fit orbit is at $89$ au ($0.59''$), with a $3\sigma$ lower limit of 30 au ($0.20''$). This finding is consistent with the simulation prediction of the location of an arm-driving planet for the two major arms in the system.
 Comments: 9 pages, 4 figures, Accepted by ApJ Letters Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR) Cite as: arXiv:1803.06776 [astro-ph.EP] (or arXiv:1803.06776v1 [astro-ph.EP] for this version)

## Submission history

From: Bin Ren Mr. [view email]
[v1] Mon, 19 Mar 2018 01:29:27 GMT (501kb,D)