JWST Imaging of Edge-on Protoplanetary Disks. II. Appearance of Edge-on Disks with a Tilted Inner Region: Case Study of IRAS04302+2247

Abstract

We present James Webb Space Telescope imaging from 2 to 21 μm of the edge-on protoplanetary disk around the embedded young star IRAS04302+2247. The structure of the source shows two reflection nebulae separated by a dark lane. The source extent is dominated by the extended filamentary envelope at ∼4.4 μm and shorter wavelengths, transitioning at 7.7 μm and longer wavelengths to more compact lobes of scattered light from the disk itself. The dark lane thickness does not vary significantly with wavelength, which we interpret as an indication for intermediate-sized (∼10 μm) grains in the upper layers of the disk. Intriguingly, we find that the brightest nebula of IRAS40302 switches side between 12.8 and 21 μm. We explore the effect of a tilted inner region on the general appearance of edge-on disks. We find that radiative transfer models of a disk including a tilted inner region can reproduce an inversion in the brightest nebula. In addition, for specific orientations, the model predicts strong lateral asymmetries, which can occur for more than half possible viewing azimuths. A large number of edge-on protoplanetary disks observed in scattered light show such lateral asymmetries (15/20), which suggests that a large fraction of protoplanetary disks might host a tilted inner region. Stellar spots may also induce lateral asymmetries, which are expected to vary over a significantly shorter timescale. Variability studies of edge-on disks would allow us to test the dominant scenario for the origin of these asymmetries.

Dracula’s Chivito: Discovery of a Large Edge-on Protoplanetary Disk with Pan-STARRS

“…The left lobe is darker in the northern part, and filament-like features can be seen extending perpendicularly from this part of the disk and also seen as an extended emission in the contours of panel (c), suggesting winds and higher extinction. These features can also possibly be part of a filamentary envelope such as the one seen in IRAS 04302 +2247 (Villenave et al 2024). Finally, the lower edge of the bright lobe shows pronounced flaring, similar to the "wings" seen in PDS 144N (Perrin et al 2006).…”

“…We investigate a possible lateral asymmetry following the method described by Villenave et al (2020) and Duchêne et al (2024) to define a spine for each lobe of the disk, setting the outer edge of each lobe as the limit where the flux drops to 5% of the peak. Villenave et al (2024) found such asymmetries in the majority of the edge-on disks investigated and interpret this effect by a tilted inner region of the disk. The result of our analysis is presented in panel (d) of Figure 1, which shows a clear lateral offset between the lobes.…”

High-resolution Pan-STARRS and SMA Observations of IRAS 23077+6707: A Giant Edge-on Protoplanetary Disk

“…With strong resemblance to the factor 3 brightness asymmetry along IRAS 23077+6707ʼs eastern lobe, Villenave et al (2024) have very recently identified a lateral brightness symmetry (with a switch in brightness at 12.8 and 21 μm) in the edge-on Class I system IRAS 04302+2247, which they attribute to a tilted inner disk. In addition, they uncover similar lateral asymmetries in optical and infrared scattered-light emission in 15 out of 20 EODs, suggesting that a significant fraction of protoplanetary disks may be hosts to tilted inner regions.…”

“…Regardless, whichever precise mechanism is driving the asymmetry in IRAS 23077+6707ʼs disk, only higher-angularresolution scattered-light observations in optical and especially near-to mid-infrared wavelengths (e.g., in order to identify the switch in brightness due to an inner tilted disk-see Villenave et al 2024; or the identification of an eccentric circumbinary disk producing similar brightness asymmetries, as, e.g., for IRAS 04158+2805-see Andrews et al 2008 andRagusa et al 2021) will be able to provide constraints on the possible origins of the asymmetries observed in IRAS 23077+6707.…”

“…On the other hand, optical and near-infrared observations trace smaller, micron-sized dust grains in the hotter, outer envelope and the disk surface layers that scatter the light of the central star and thus create two bright, highly flared lobes. Thanks to the Karl G. Jansky Very Large Array, the Atacama Large Millimeter Array, the Hubble Space Telescope, and most recently the James Webb Space Telescope, scattered-light and (sub)millimeter observations of EODs at high spatial resolution have now become routine (e.g., Melis et al 2011;Stapelfeldt et al 2014;Villenave et al 2020;Flores et al 2021;Duchene et al 2024;Villenave et al 2024). However, the angular extents of these EODs are generally only a few arcseconds at most, with IRAS 18059-3211 ("Gomez's Hamburger") presenting the largest yet, with dust and gas extents of 9″ and 12″ respectively (Ruiz et al 1987;Bujarrabal et al 2008Bujarrabal et al , 2009Teague et al 2020).…”