Star formation in G11.497-1.485: Two-epoch VLA study of a 6.7 GHz methanol maser flare^⋆

¹ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
e-mail: olga.bayandina@inaf.it
² RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
³ INAF – Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy
⁴ Dublin Institute for Advanced Studies, School of Cosmic Physics, Astronomy & Astrophysics Section, 31 Fitzwilliam Place, Dublin 2, Ireland
⁵ Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Antig. Carr. a Patzcuaro 8701, Morelia 58089, Mexico
⁶ Astro Space Center, P.N. Lebedev Physical Institute of RAS, 84/32 Profsoyuznaya st., Moscow 117997, Russia
⁷ Ural Federal University, 19 Mira Str., 620002 Ekaterinburg, Russia
⁸ Center for Astronomy, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan

Received: 17 November 2023
Accepted: 23 January 2024

Abstract

Context. Maser flares are particularly significant in the study of massive star formation as they not only signal but also provide unique insights into transient phenomena such as accretion bursts.

Aims. With this project, we aim to investigate the context of the ongoing 6.7 GHz methanol maser flare in the little-known massive star-forming region G11.497-1.485.

Methods We carried out two epochs of the Karl G. Jansky Very Large Array (VLA) observation for 6.7 GHz and 12 GHz class II methanol, 22 GHz water masers, and continuum in the C, Ku, and K bands.

Results. The VLA overview revealed the presence of five distinct radio-continuum sources (CM1-4 and N) in G11.497-1.485. The central source, CM1, is found to show signs of accretion disc fragmentation, highlighted by the centimetre-continuum-traced fragments, and is found to drive a high-energy jet, the ends of which are marked by non-thermal knots CM2 and CM3. CM1 showed a gradual flaring of methanol masers and a fading of a 22 GHz water maser, which might be signalling an accretion burst. The two remaining sources of the region, CM4 and N, make up one of the most compact jet and disc–jet systems found to date.

Conclusions. The obtained data reveal, for the first time, the structure of the G11.497-1.485 region. The change in fluxes of the maser and the continuum emission confirm a transient event and reveal its impact on multiple sources in the region.