Anatomy of the Class I protostar L1489 IRS with NOEMA

I. Disk, streamers, outflow(s) and bubbles at 3 mm^★

¹ Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
e-mail: maxime.tanious@univ-grenoble-alpes.fr; romane.le-gal@univ-grenoble-alpes.fr
² IRAM, 300 rue de la piscine, 38406 Saint-Martin-d’Hères, France
³ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
⁴ Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA
⁵ Department of Astronomy, Columbia University, 538 W. 120th Street, Pupin Hall, New York, NY, USA
⁶ Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA

Received: 29 November 2023
Accepted: 23 March 2024

Abstract

Context. Over the past few years, chemical studies have revealed multiple structures in the vicinity of young stellar objects (YSOs). It has become evident that specific physical conditions are associated with the emission of particular molecular lines, allowing us to use molecular probes of the YSO physics. Consequently, chemical surveys are now necessary to fully constrain the origin of the observed structures. Several surveys have been conducted to explore the chemistry of YSOs, focusing on Class 0 and Class II objects. However, our knowledge of intermediate objects, that are Class I objects, remains limited.

Aims. To bridge the gap and establish the relationship between observed structures and molecular line emission at the Class I evolutionary stage, we investigate the spatial distribution of key molecular gas species in the low-mass Class I protostar L1489 IRS (IRAS 04016+2610), a source part of the ChemYSO survey.

Methods. We performed a 3 mm line survey at high spatial and high spectral resolution using the NOEMA interferometer and the IRAM-30 m telescope. For the data analysis, we applied and compared two methods: a streamline model and the new python package TIPSY.

Results. We present here the ten brightest lines of our survey, in which we identified a new ~3000 au long streamer in HC₃N, C₂H, and c–C₃H₂ emission, likely associated with more localized accretion shocks probed in SO. In addition, two ~10 000 au bubbles are seen with the dense molecular tracers HCO⁺, CS, and HCN around the YSO. We retrieve previously identified structures, like an outflow in HCO⁺ and another streamer in C₂H. Additionally, potential indicators of a second outflow appear in CS and HCN emission, but its nature remains to be confirmed.

Conclusions. The late infall identified at large scales may originate from the nearby prestellar core L1489 and is likely responsible for the formation of an external warped disk in this system. The detection of a potential second outflow could be the direct evidence of a binary system. Finally, we hypothesize that the bubbles may result from the magnetic pressure as observed in numerical simulations.