Hunting for the Exoplanets in HD 100546's Protoplanetary Disk

The SPHERE view of the planet-forming disk around HD100546

Authors:

Garufi et al

Abstract:

We image with unprecedented spatial resolution and sensitivity disk features that could be potential signs of planet-disk interaction. Two companion candidates have been claimed in the disk around the young Herbig Ae/Be star HD100546. Thus, this object serves as an excellent target for our investigation of the natal environment of giant planets. We exploit the power of extreme adaptive optics operating in conjunction with the new high-contrast imager SPHERE to image HD100546 in scattered light. We obtain the first polarized light observations of this source in the visible (with resolution as fine as 2 AU) and new H and K band total intensity images that we analyze with the Pynpoint package. The disk shows a complex azimuthal morphology, where multiple scattering of photons most likely plays an important role. High brightness contrasts and arm-like structures are ubiquitous in the disk. A double-wing structure (partly due to ADI processing) resembles a morphology newly observed in inclined disks. Given the cavity size in the visible (11 AU), the CO emission associated to the planet candidate 'c' might arise from within the circumstellar disk. We find an extended emission in the K band at the expected location of 'b'. The surrounding large-scale region is the brightest in scattered light. There is no sign of any disk gap associated to 'b'.

HD 100546b is a SuperJovian and HD 100546c is a SuperJovian at 13 AU

Resolving the HD 100546 Protoplanetary System with the Gemini Planet Imager: Evidence for Multiple Forming, Accreting Planets

Authors:

Currie et al

Abstract:

We report Gemini Planet Imager H band high-contrast imaging/integral field spectroscopy and polarimetry of the HD 100546, a 10 Myr-old early-type star recently confirmed to host a thermal infrared bright (super)jovian protoplanet at wide separation, HD 100546 b. We resolve the inner disk cavity in polarized light, recover the thermal-infrared (IR) bright arm, and identify one additional spiral arm. We easily recover HD 100546 b and show that much of its emission originates an unresolved, point source. HD 100546 b likely has extremely red infrared colors compared to field brown dwarfs, qualitatively similar to young cloudy superjovian planets, however, these colors may instead indicate that HD 100546 b is still accreting material from a circumplanetary disk. Additionally, we identify a second point source-like peak at rproj ∼ 13 AU, located just interior to or at inner disk wall consistent with being a 10--20 MJ candidate second protoplanet-- "HD 100546 c" -- and lying within a weakly polarized region of the disk but along an extension of the thermal IR bright spiral arm. Alternatively, it is equally plausible that this feature is a weakly polarized but locally bright region of the inner disk wall. Astrometric monitoring of this feature over the next 2 years and emission line measurements could confirm its status as a protoplanet, rotating disk hot spot that is possibly a signpost of a protoplanet, or a stationary emission source from within the disk.

Are the gas Giants in HD 100546's Protoplanetary Disk Forming Sequentially?

Sequential planet formation in the HD 100546 protoplanetary disk?

Authors:

Pinilla et al

Abstract:

Context.

The disk around the Herbig Ae star, HD 100546, shows structures that suggest the presence of two companions in the disk at ∼10 and ∼70 AU. The outer companion seems to be in the act of formation.

Aims.

Our aims are to provide constraints on the age of the planets in HD 100546 and to explore the potential evidence for sequential planet formation in transition disks such as HD 100546.

Methods.

We compare the recent resolved continuum observations of the disk around HD 100546 with the results of dust evolution simulations using an analytical prescription for the shapes of gaps carved by massive planets.

Results.

An inner pressure bump must have been present since early in the disk lifetime to have good agreement between the dust evolution models and the continuum observations of HD 100546. This pressure bump may have resulted from the presence of a very massive planet (∼20MJup), which formed early in the inner disk (r∼10 AU). If only this single planet exists, the disk is likely to be old, comparable to the stellar age (∼5-10 Myr). Another possible explanation is an additional massive planet in the outer disk (r∼70 AU): either a low-mass outer planet (≲5MJup) injected at early times, or a higher mass outer planet (≳15MJup) formed very recently, traps the right amount of dust in pressure bumps to reproduce the observations. In the latter case, the disk could be much younger (∼3.0 Myr).

Conclusions.

In the case in which two massive companions are embedded in the disk around HD 100546, as suggested in the literature, the outer companion could be at least ≳2.5 Myr younger than the inner companion.