SMA and NOEMA reveal asymmetric sub-structure in the protoplanetary disk of IRAS23077+6707

Abstract

We present high-resolution data of IRAS 23077+6707 (`Dracula's Chivito') with the Submillimeter Array (SMA at 1.33 mm/225.5 GHz) and the Northern Extended Millimeter Array (NOEMA at 2.7 mm/111.7 GHz and 3.1 mm/96.2 GHz). IRAS 23077+6707 is a highly-inclined and newly discovered protoplanetary disk, first reported in 2024. We combine SMA baselines from the Compact, Extended and Very Extended arrays, and NOEMA baselines from its A and C configurations, and present continuum images with resolution ${\lesssim}0.8''$, which constitute the first sub-arcsecond resolution maps of IRAS 23077+6707. The images show extended linear emission that spans $5.6{-}6.1''$ as expected for a radially extended, highly-inclined protoplanetary disk. Accompanied with lower resolution data, we show that the disk has a steep spectral index, ranging from $α=3.2{-}3.9$. We present evidence of multiple radial emission peaks and troughs in emission, which may originate in disk rings and a central cavity. We further present evidence that these radial structures are asymmetric; hosting a a significant brightness asymmetry, with emission enhanced by up to 50% in the north versus the south. We discuss hypotheses about the potential origins of these features, including the possibility that IRAS 23077+6707 hosts a rare example of an eccentric protoplanetary disk, which can induce these radially asymmetric structures. We present a simple eccentric continuum model of IRAS 23077+6707, and show for an eccentricity of $e \approx 0.26$, that this can reproduce the bulk morphology of the emission.