Outflow interaction in Cep-E

Numerical simulation and observational manifestation

¹ Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ap. 70-543, 04510, Ciudad de México, Mexico
² Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, 58090 Morelia, Michoacán, Mexico
³ LUX Observatoire de Paris, CNRS, PSL, Université de Paris, 5 Place Jules Janssen, 92190 Meudon, France

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 26 June 2024
Accepted: 16 January 2026

Abstract

Context. There is clear observational evidence that the main Class 0/I stages of the star formation process are associated with powerful collimated outflows (jets), which sometimes propagate up to distances as large as 10⁴⁻⁵ au in molecular clouds. Additionally, intermediate high-mass and low-mass protostars have often been observed to form in crowded clusters, where the typical separation distance between any two cluster members is on the same order or smaller than the scale of the outflow length. Therefore, there must be an interaction between the molecular outflows of different protostars within the protostellar association. A good example of this is the case of Cepheus E-mm, which is a protostellar outflow extending over a few dozen astronomical units. At its core is a binary system consisting of two protostars, Cep E-A and Cep E-B, separated by about 1000 au. Both protostars eject molecular jets at velocities of 100 km/s. The interaction between these molecular outflows provides an opportunity to study the effects of jet collisions in a clustered star-forming environment, as they may leave detectable imprints on the morphology of the main envelope of the system.

Aims. Our work aims to study the effects of the collision of molecular jets associated with the components of the binary system Cep-A and Cep-E, analyzing the disruption or reduction of molecular emission in the main envelope of the system, which the molecular outflow launched by Cep-A presumably pushes. If we characterize the collision in this system, we can provide insights into the expected morphology and molecular emissions in collisions of molecular outflows associated with the star formation process.

Methods. We used the 3D hydrodynamical code to model a system of two protostellar jets powered by two sources interacting in a configuration similar to the prototypical intermediate-mass protobinary system Cep E. Maps of density, emissivity, and velocity distribution were produced, which allowed direct comparison with these observations.

Results. We found signatures of outflow interaction that can be used to find more interaction cases.