HD 100453 has an M Dwarf Hiding in its Protoplanetary Disk, Causing Spiral Arms

An M Dwarf Companion and Its Induced Spiral Arms in the HD 100453 Protoplanetary Disk

Authors:

Dong et al

Abstract:

Recent VLT/SPHERE near-infrared imaging observations revealed two spiral arms with a near m=2 rotational symmetry in the protoplanetary disk around the ~1.7 solar mass Herbig star HD 100453. A ~0.3 solar mass M dwarf companion, HD 100453 B, was also identified at a projected separation of 120 AU from the primary. In this Letter, we carry out hydrodynamic and radiative transfer simulations to examine the scattered light morphology of the HD 100453 disk as perturbed by the companion on a circular and coplanar orbit. We find that the companion truncates the disk at ~45 AU in scattered light images, and excites two spiral arms in the remaining (circumprimary) disk with a near m=2 rotational symmetry. Both the truncated disk size and the morphology of the spirals are in excellent agreement with the SPHERE observations at Y , J, H, and K1-bands, suggesting that the M dwarf companion is indeed responsible for the observed double-spiral-arm pattern. Our model suggests that the disk is close to face on (inclination angle ~5 degree), and that the entire disk-companion system rotates counterclockwise on the sky. The HD 100453 observations, along with our modeling work, demonstrate that double spiral arm patterns in near-infrared scattered light images can be generically produced by companions, and support future observations to identify the companions responsible for the arms observed in the MWC 758 and SAO 206462 systems.

Discovery of a Two-Armed Spiral Structure in the Gapped Disk in HD 100453

Discovery of a Two-Armed Spiral Structure in the Gapped Disk in HD 100453

Authors:

Wagner et al

Abstract:

We present VLT/SPHERE adaptive optics imaging in Y−, J−, H−, and K-bands of the HD 100453 system and the discovery of a two-armed spiral structure in a disk extending to 0.37" (∼42 AU) from the star, with highly symmetric arms to the Northeast and Southwest. Inside of the spiral arms, we resolve a ring of emission from 0.18"-0.25" (∼21-29 AU). By assuming that the ring is intrinsically circular we estimate an inclination of ∼34o from face-on. We detect dark crescents on opposite sides (NW and SE) which begin at 0.18" and continue to radii smaller than our inner working angle of 0.15", which we interpret as the signature of a gap at ≲21 AU that has likely been cleared by forming planets. We also detect the ∼120 AU companion HD 100453 B, and by comparing our data to 2003 HST/ACS and VLT/NACO images we estimate an orbital period of ∼850 yr. We discuss what implications the discovery of the spiral arms and finer structures of the disk may have on our understanding of the possible planetary system in HD 100453, and how the morphology of this disk compares to other related objects.

Large Dust Gaps in the Transitional Disks of HD 100453 and HD 34282

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

Authors:

Khalafinejad et al

Abstract:

The formation of dust gaps in protoplanetary disks is one of the most important signposts of disk evolution and possibly the formation of planets. 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{\mu}m, but very weak (HD 100453) and no (HD 34282) signs of the 10 and 20 {\mu}m amorphous silicate features. We investigate whether this implies the presence of large dust gaps. In this work, spatially resolved mid-infrared Q-band images taken with Gemini North/MICHELLE are investigated. We perform radiative transfer modeling and examine the radial distribution of dust. We simultaneously fit the Q-band images and SEDs of HD 100453 and HD 34282. Our solutions require that the inner-halos and outer-disks are likely separated by large dust gaps that are depleted wih 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 about 160±10 K and 60±5 K respectively. Because of the high surface brightnesses of these walls, they dominate the emission in the Q-band. Their radii are constrained at 20+2 AU and 92+31 AU, respectively. We conclude that, HD 100453 and HD 34282 likely have disk dust gaps and the upper limit on the dust mass in each gap is estimated to be about 10−7M⊙. We find that the locations and sizes of disk dust gaps are connected to the SED, as traced by the mid-infrared flux ratio F30/F13.5. We propose a new classification scheme for the Meeus groups (Meeus et al. 2001) based on the F30/F13.5 ratio. The absence of amorphous silicate features in the observed SEDs is caused by the depletion of small (smaller than 1 {\mu}m) silicate dust at temperatures above 160 K, which could be related to the presence of a dust gap in that region of the disk.