Ongoing star formation in the protocluster IRAS 22134+5834

¹ Department of Astronomy, University of Geneva, Chemin d’Écogia 16, 1290 Versoix, Switzerland
e-mail: yuan.wang@unige.ch
² Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, 210008 Nanjing, PR China
³ INAF–Osservatorio Astrofisico di Arcetri, L.go E. Fermi 5, 50125 Firenze, Italy
⁴ I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Cologne, Germany
⁵ Insitut de Ciències de l’Espai (CSIC-IEEC), Campus UAB, carrer de Can Magran S/N 08193, Cerdanyola del Vallès, 08193 Catalunya, Spain
⁶ Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía, s/n 18008 Granada, Spain
⁷ Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, PO Box 3-72, 58090 Morelia, Michoacán, Mexico
⁸ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁹ Departments of Astronomy and Physics, University of Florida, Gainesville, FL 32611, USA
¹⁰ Dept. d’Astronomia i Meteorologia, Institut de Ciencies del Cosmos, Univ. de Barcelona, IEEC-UB, Marti Franques 1, 08028 Barcelona, Spain
¹¹ Department of Physics & Astronomy – MS 108, Rice University, 6100 Main Street, Houston, TX 77005, USA
¹² Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint-Martin d’ Hères, France
¹³ University College London, Department of Physics and Astronomy, 132 Hampstead Road, London NW1 2PS, UK

Received: 29 May 2015
Accepted: 6 October 2015

Abstract

Aims. Massive stars form in clusters, and their influence on nearby starless cores is still poorly understood. The protocluster associated with IRAS 22134+5834 represents an excellent laboratory for studying the influence of massive YSOs on nearby starless cores and the possible implications in the clustered star formation process.

Methods. IRAS 22134+5834 was observed in the cm range with (E)VLA, 3 mm with CARMA, 2 mm with PdBI, and 1.3 mm with SMA, to study both the continuum emission and the molecular lines that trace different physical conditions of the gas.

Results. The multiwavelength centimeter continuum observations revealed two radio sources within the cluster, VLA1 and VLA2. VLA1 is considered to be an optically thin UCHii region with a size of 0.01 pc that sits at the edge of the near-infrared (NIR) cluster. The flux of ionizing photons of the VLA1 corresponds to a B1 ZAMS star. VLA2 is associated with an infrared point source and has a negative spectral index. We resolved six millimeter continuum cores at 2 mm, MM2 is associated with the UCHii region VLA1, and other dense cores are distributed around the UCHii region. Two high-mass starless clumps (HMSC), HMSC-E (east) and HMSC-W (west), are detected around the NIR cluster with N₂H⁺(1–0) and NH₃ emission, and they show different physical and chemical properties. Two N₂D⁺ cores are detected on an NH₃ filament close to the UCHii region with a projected separation of ~8000 AU at the assumed distance of 2.6 kpc. The kinematic properties of the molecular line emission confirm that the UCHii region is expanding and that the molecular cloud around the NIR cluster is also expanding.

Conclusions. Our multiwavelength study has revealed different generations of star formation in IRAS 22134+5834. The formed intermediate-to-massive stars show a strong impact on nearby starless clumps. We propose that the starless clumps and HMPOs formed at the edge of the cluster while the stellar wind from the UCHii region and the NIR cluster drives the large scale bubble.