SMA and NOEMA Reveal Asymmetric Substructure in the Protoplanetary Disk of IRAS 23077+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 ≲0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 8, which constitute the first subarcsecond resolution maps of IRAS 23077+6707. The images show extended linear emission that spans 5 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 6–6 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 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 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 ≈ 0.26, that this can reproduce the bulk morphology of the emission.