Friday, September 23, 2016

2MASS J16042165-2130284 Probably has a Brown Dwarf & Several Gas Giants


Wilson Canovas et al


2MASS J16042165-2130284 (hereafter J1604) is a pre-transitional disk with different gap sizes in the mm-sized (~79 au) and μm-sized (~63 au) dust particles. The 12CO emission shows a ~30 au cavity. This radial structure suggests that giant planets are interacting with the disk.
We aim to observationally constrain the masses and location of plausible giant planets inside the cavity of J1604, and compare our results with previous predictions from hydrodynamical models describing planet-disk interactions.

We observed J1604 with VLT/SPHERE in pupil-stabilized mode, obtaining YJHK- band images. The dataset was processed exploiting the ADI technique with dedicated algorithms to maximize the sensitivity of our observations.

Our observations reach an exquisite contrast of ΔK,H 12 mag from 0.15" to 0.80" ( 22 to 115 au), but no planet candidate is detected. The disk is directly imaged in scattered light in all the near infrared bands (from Y to K). The disk has a red color, which indicates that the dust particles in the disk surface are mainly ≳0.3μm-sized grains. We confirm the sharp dip/decrement in scattered light in agreement with previous observations. Comparing our images with a simple radiative transfer model we argue that the nearest side of the disk is most likely the southern side.

Our observations represent a gain of roughly ΔK=6 in contrast when compared to previous observations of this object. The work detailed here represents the deepest search yet for companions of J1604 which are potentially carving its disk structure. We reach a mass sensitivity of 2−3MJup across the disk cavity according to a hot start scenario. We propose that a brown dwarf orbiting inside the inner ~15 au and additional Jovian planets at larger radii could account for the observed properties of J1604 while explaining our non-detection.

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