Large dust gaps in the transitional disks of HD 100453 and HD 34282

Abstract

Context. The formation of dust gaps in protoplanetary disks is one of the most important signs of disk evolution and might indicate the formation of planets. Aims. We aim to characterize the flaring disk structure around the Herbig Ae/Be stars HD 100453 and HD 34282. Their spectral energy distributions (SEDs) show an emission excess between 15−40 µm, but very weak (HD 100453) and no (HD 34282) signs of the 10 and 20 µm amorphous silicate features. We investigate whether this implies the presence of large dust gaps. Methods. We investigated spatially resolved mid-infrared Q-band images taken with Gemini North/MICHELLE. We performed radiative transfer modeling and examined the radial distribution of dust. We simultaneously fit the Q-band images and SEDs of HD 100453 and HD 34282. Results. Our solutions require that the inner halos and outer disks be separated by large dust gaps that are depleted with respect to the outer disk by a factor of 1000 or more. The inner edges of the outer disks of HD 100453 and HD 34282 have temperatures of ∼160 ± 10 K and ∼60 ± 5 K, respectively. Because of the high surface brightness of these walls, they dominate the emission in the Q band. Their radii are constrained at 20 +2 −2 AU and 92 +31 −17 AU, respectively. Conclusions. HD 100453 and HD 34282 most likely have disk dust gaps. The upper limit of the dust mass in each gap is estimated to be about 10 −7 M . We find that the locations and sizes of disk dust gaps are connected to the SED, as traced by the mid-infrared flux ratio F 30 /F 13.5 . We propose a new classification scheme for the Meeus groups based on the F 30 /F 13.5 ratio. The absence of amorphous silicate features in the observed SEDs is caused by the depletion of small ( 1 µm) silicate dust at temperatures above 160 K, which could be related to the presence of a dust gap in that region of the disk.

Polycyclic Aromatic Hydrocarbons in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars

“…This, together with SED analysis, indicates the presence of a gap in the disk (e.g., Mariñas et al 2011;Maaskant et al 2013;Khalafinejad et al 2016). A spatially resolved MIR Q-band image obtained with Gemini north/MICHELLE indicates that the outer edge of the gap is at 20 +3 −3 AU and the disk is extended up to ∼ 200 AU (Khalafinejad et al 2016).…”

Observations and modelling of CO and [C i] in protoplanetary disks

“…Two early-type disks lie below even the late-type locus on the CO 6−5 axis. Two of these resemble debris disks: HD 141569 is a transitional disk with no substantial surface density at radii below ∼95 au (Dent et al 2005;Jonkheid et al 2006), and HD 100453 has a CO-based gas mass of only 10 −4 M and an inner cavity of 20 au (Khalafinejad et al 2016;Collins et al 2009). …”

The Shadow Knows: Using Shadows to Investigate the Structure of the Pretransitional Disk of HD 100453

“…Data reduction is described in Wagner et al (2015). Photometry used in constructing the SED of HD 100453 includes all sources mentioned in Khalafinejad et al (2016) as well as Herschel PACS data at 70, 100, and 160 μm (Pascual et al 2015), and 2MASS at J, H, and Ks bands (Cutri et al 2003).…”