The sharpest view on the high-mass star-forming region S255IR: Near infrared adaptive optics imaging of the outbursting source NIRS3
Journal article, 2023

Context. Massive stars have an impact on their surroundings from early in their formation until the end of their lives. However, very little is known about their formation. Episodic accretion may play a crucial role in the process, but only a handful of observations have reported such events occurring in massive protostars. Aims. We aim to investigate the outburst event from the high-mass star-forming region S255IR where the protostar NIRS3 recently underwent an accretion outburst. We follow the evolution of this source both in photometry and morphology of its surroundings. Methods. We performed near infrared adaptive optics observations on the S255IR central region using the Large Binocular Telescope in the Ks broadband as well as the H2 and Brγ narrow-band filters with an angular resolution of 07.06, close to the diffraction limit. Results. We discovered a new near infrared knot north-east of NIRS3 that we interpret as a jet knot that was ejected during the last accretion outburst and observed in the radio regime as part of a follow-up after the outburst. We measured a mean tangential velocity for this knot of 450 ± 50 km s1. We analysed the continuum-subtracted images from H2, which traces jet-shocked emission, and Brγ, which traces scattered light from a combination of accretion activity and UV radiation from the central massive protostar. We observed a significant decrease in flux at the location of NIRS3, with K = 13.48 mag being the absolute minimum in the historic series. Conclusions. Our observations strongly suggest a scenario where the episodic accretion is followed by an episodic ejection response in the near infrared, as was seen in the earlier radio follow-up. The ~2 μm photometry from the past 30 yr suggests that NIRS3 might have undergone another outburst in the late 1980s, making it the first massive protostar with such evidence observed in the near infrared.

Stars: massive

Stars: individual: S255IR NIRS3

ISM: jets and outflows

Techniques: high angular resolution

Stars: pre-main sequence

ISM: kinematics and dynamics


Rubén Fedriani

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

Institute of Astrophysics of Andalusia (IAA)

A. Caratti o. Garatti

Osservatorio Astronomico di Capodimonte

R. Cesaroni

Arcetri Astrophysical Observatory

Jonathan Tan

University of Virginia

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

B. Stecklum

Thüringer Landessternwarte Tautenburg

L. Moscadelli

Arcetri Astrophysical Observatory

M. Koutoulaki

University of Leeds

Giuliana Cosentino

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

M. Whittle

University of Virginia

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 676 A107

Eld ur is - den massiva stjärnbildningens utvecklingsstadier

Swedish Research Council (VR) (2017-04522), 2018-01-01 -- 2021-12-31.

Shock Compressions in the Interstellar Medium as triggers of Star Formation

Swedish Research Council (VR) (2021-05589), 2022-01-01 -- 2023-12-31.

Star formation history of MAssive pRoTostars (SMART)

European Commission (EC) (EC/H2020/101032092), 2021-04-01 -- 2023-03-31.

Subject Categories

Subatomic Physics

Meteorology and Atmospheric Sciences

Astronomy, Astrophysics and Cosmology



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9/5/2023 1