The Circumstellar Disk HD 169142: Gas, Dust, and Planets Acting in Concert?*

Abstract

HD 169142 is an excellent target for investigating signs of planet-disk interaction due to previous evidence of gap structures. We perform J-band (∼1.2 μm) polarized intensity imaging of HD 169142 with VLT/SPHERE. We observe polarized scattered light down to 0 16 (∼19 au) and find an inner gap with a significantly reduced scattered-light flux. We confirm the previously detected double-ring structure peaking at 0 18 (∼21 au) and 0 56 (∼66 au) and marginally detect a faint third gap at 0 70-0 73 (∼82-85 au). We explore dust evolution models in a disk perturbed by two giant planets, as well as models with a parameterized dust size distribution. The dust evolution model is able to reproduce the ring locations and gap widths in polarized intensity but fails to reproduce their depths. However, it gives a good match with the ALMA dust continuum image at 1.3 mm. Models with a parameterized dust size distribution better reproduce the gap depth in scattered light, suggesting that dust filtration at the outer edges of the gaps is less effective. The pileup of millimeter grains in a dust trap and the continuous distribution of small grains throughout the gap likely require more efficient dust fragmentation and dust diffusion in the dust trap. Alternatively, turbulence or charging effects might lead to a reservoir of small grains at the surface layer that is not affected by the dust growth and fragmentation cycle dominating the dense disk midplane. The exploration of models shows that extracting planet properties such as mass from observed gap profiles is highly degenerate.

Long-lived Dust Rings around HD 169142

“…According to Panić et al (2008) observations in the 1.3 mm dust continuum and CO (J = 2 − 1) emission line the disc has an inclination of 13 degrees, a position angle of 5 degrees and a total gas mass of ∼ 0.6 − 3.0 × 10 −2 M , confirmed by subsequent observations (Fedele et al 2017;Perez et al 2019, hereafter FD17 and PS19). This source has been observed in the thermal mid-infrared emission (Honda et al 2012), near-infrared emission (Reggiani et al 2014;Pohl et al 2017;Ligi et al 2018;Bertrang et al 2018), near-infrared polarimetric and scattered light images (Pohl et al 2017). Gas and dust are physically decoupled in HD 169142.…”

“…Many authors (FD17, Pohl et al 2017;Ligi et al 2018;Bertrang et al 2018, ME18, PS19) pointed out the presence of giant planets in the disc (M > few Jupiter masses, hereafter M J ), an inner one located inside the inner dust cavity (R < 20 au) and an outer one in the gap between the two dust rings (35 < R < 55 au) to explain the signature double-ring morphology. The splitting of the outer ring in concentric rings have been modeled by PS19 with the presence of a single migrating low mass planet (∼ 10 −2 M J ).…”

ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT)

“…However, the millimeter observations by Guilloteau et al (2011) constrained the disk inclination to only ∼ 65 • , implying that the disk opening angle for small particles in the outer regions is larger than 90 • − 65 • = 25 • . In several Class II sources with more inclined disks, the star is not obscured by the disk (see, e.g., Pohl et al 2017;Langlois et al 2018;Avenhaus et al 2018). This implies that the earlytype SED of DG Tau B is due to its young evolutionary stage and not by a coincidental alignment of disk and line of sight.…”

Homogeneous Analysis of the Dust Morphology of Transition Disks Observed with ALMA: Investigating Dust Trapping and the Origin of the Cavities

“…ALMA has confirmed that TDs are a very diverse set of protoplanetary disks, for which several gas and dust morphologies have been observed. Complementary to ALMA data, extreme adaptive optics and coronagraphic observations at optical and near-infrared wavelengths have also enriched our knowledge of the TDs structures (e.g., Follette et al 2013;Avenhaus et al 2014;de Boer et al 2016;Pohl et al 2017a). The combination of high-resolution observations at different wavelengths has shown how the distribution of micron-sized particles traced at short wavelengths can significantly differ from the distribution of millimeter-sized particles (e.g., Garufi et al 2013;Pinilla et al 2015b;Hendler et al 2018).…”