Parameters and models of the jets from Sanduleak’s star in the LMC

¹ Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ap. 70-543, 04510 Cd. Mx., Mexico
e-mail: artemi.camps@correo.nucleares.unam.mx; raga@nucleares.unam.mx
² Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

Received: 2 March 2018
Accepted: 7 August 2018

Abstract

Context. Angeloni and collaborators have discovered a bipolar jet extending out to ~6 pc from “Sanduleak’s star” in the Large Magellanic Cloud (LMC). This is the first angularly resolved stellar jet system that has been observed outside our Galaxy.

Aims. In this paper we use archival Hubble Space Telescope (HST) images of this jet in order to estimate the flow parameters, and use them to explore two possible theoretical scenarios for modelling this bipolar outflow.

Methods. We have computed axisymmetric gasdynamic simulations of a conical outflow with an opening angle that increases with time and of a cylindrical jet interacting with a stratified circumstellar structure. The results of these models are then compared with the observed morphology of the jets from Sanduleak’s star.

Results. From the observations, we obtain Ṁ_j ≈ 1.2 × 10⁻⁵M_⊙ yr⁻¹ and L_m ≈ 1000 L_⊙ for the mass loss rate and the mechanical luminosity (respectively) of each of the outflow lobes. We also obtain a (deprojected) flow velocity v_j ≈ 1000 km s⁻¹ and a dynamical time t_dyn ≈ 7300 yr. From the simulations that we have computed (with these flow parameters), we find that both the “opening out conical wind” and the “jet+stratified environment” scenarios have characteristics that resemble the observed morphologies. A more complete model for the jets from Sanduleak’s star might incorporate some of the features of these two scenarios.