ALMAGAL
Astronomy and Astrophysics, vol. 709, pp. A173
Abstract
Context . Several theoretical and observational studies have shown that new waves of triggered star formation can be induced by the feedback from newly formed massive protostars, due to the expansion of H II regions. Aims . We used the millimeter dust continuum data of the ALMAGAL survey and the Anderson et al. (2014) catalog of H II regions to search for signatures of possible triggered star formation at its onset, and selected one ALMAGAL source for ALMA follow-up observations. Methods . For this study we selected the source AG286.0716–1.8229, in which six cores were detected at a resolution of ~7600 au, but only two at a higher resolution. The four cores not detected at higher resolution are prestellar core candidates. We used archival data from the SARAO Meerkat Galactic Plane Survey and Rapid Askap Continuum Survey to confirm whether a H II region is present in the field. We observed the source with ALMA in Band 4, covering the emission of DCO + (2–1), N 2 D + (2–1), DCN (2–1), and CH 3 CCH (9–8), to infer from the chemical composition and temperature estimates whether these cores are in an early phase of the star-formation process, which allows us to classify them as prestellar cores. The new Band 4 continuum image revealed additional three cores outside of the ALMAGAL field of view (FoV), making a total of nine cores in the region, eight of which are located along an arch that has a radius of ~0.75 pc. We also used the continuum and molecular emission to estimate the mass of these cores, to determine whether they are gravitationally bound or transient objects. Results . We have derived a spectral index between −0.14 and −0.4, in the frequency range of 0.8–1.6 GHz for the candidateH II region, which is consistent with optically thin free-free emission. The H II region spatially coincides (as projected on the plane of the sky) with the position of one of the cores, which in the new ALMA Band 4 observations does not have a compact morphology. The N 2 D + and DCO + emission peaks at the position of three out of four prestellar core candidates, and the overall emission in both the line and the continuum, which extends outside of the FoV of the ALMAGAL observations, reveals a clear arched shape centered on the H II region. We were able to estimate the gas temperature of only the most evolved core, using the CH 3 CCH emission. The resulting value of 39 ± 5 K is also an upper limit for the other cores. Using plausible temperature ranges for each core, based on the information from chemical tracers and the dust continuum, we derived mass ranges for the cores (~2–16 M ⊙ ) as well as ranges for the virial parameter (~0.3–5). All the cores along the arch have virial parameters consistent with bound objects, with only one exception. Conclusions . Comparing the typical separation and mass of the cores with those expected in the case of the collect and collapse scenario and with the thermal Jean length and mass, the best agreement is found with the characteristic scales in the case of triggered star formation. The same methodology can be applied to further ALMAGAL sources to identify optimal targets to study a larger sample of prestellar cores in an environment affected by the presence of a H II region.
Authors 52
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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University of Cologne · Max Planck Institute for Radio Astronomy
Affiliation as printed
I. Physikalisches Institut, Universität zu Köln
Max-Planck-Institut für Radioastronomie
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Max Planck Society · Arcetri Astrophysical Observatory · Observatoire de Paris · Max Planck Institute for Extraterrestrial Physics · Laboratoire d'Étude de l'Univers et des Phénomènes Extrêmes · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio Astrofisico di Arcetri
Laboratory for the study of the Universe and eXtreme phenomena (LUX), Observatoire de Paris
Max-Planck-Institute for Extraterrestrial Physics (MPE)
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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University of Rome Tor Vergata · Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
Dipartimento di Fisica, Università di Roma Tor Vergata
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Affiliation as printed
I. Physikalisches Institut, Universität zu Köln
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Institute of Space Sciences · Institut d'Estudis Espacials de Catalunya
Affiliation as printed
Institut de Ciències de l’Espai (ICE), CSIC, Campus UAB, Carrer de Can Magrans s/n
Institut d’Estudis Espacials de Catalunya (IEEC)
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Affiliation as printed
I. Physikalisches Institut, Universität zu Köln
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Affiliation as printed
University of Connecticut, Department of Physics
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Institute of Astronomy and Astrophysics, Academia Sinica · East Asian Observatory · Academia Sinica
Affiliation as printed
East Asian Observatory
Institute of Astronomy and Astrophysics, Academia Sinica
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Arcetri Astrophysical Observatory · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio Astrofisico di Arcetri
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Max Planck Institute for Astronomy
Affiliation as printed
Max Planck Institute for Astronomy
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Affiliation as printed
I. Physikalisches Institut, Universität zu Köln
Jodrell Bank Centre for Astrophysics
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Affiliation as printed
I. Physikalisches Institut, Universität zu Köln
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Harvard University · Heidelberg University · Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics | Harvard & Smithsonian
Elizabeth S. and Richard M. Cashin Fellow at the Radcliffe Institute for Advanced Studies at Harvard University
Universität Heidelberg, Interdisziplinäres Zentrum für Wissenschaftliches Rechnen
Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics | Harvard & Smithsonian
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Affiliation as printed
Center for Data and Simulation Science, University of Cologne
I. Physikalisches Institut, Universität zu Köln
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Institute of Astronomy and Astrophysics, Academia Sinica · Academia Sinica
Affiliation as printed
Institute of Astronomy and Astrophysics, Academia Sinica
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Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, Netherlands Institute for Radio Astronomy
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Arcetri Astrophysical Observatory · University of Florence · National Institute for Astrophysics
Affiliation as printed
Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze
INAF-Osservatorio Astrofisico di Arcetri
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Affiliation as printed
Jodrell Bank Centre for Astrophysics
SKA Observatory, Jodrell Bank, Lower Withington
UK ALMA Regional Centre Node
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Universidad Nacional Autónoma de México
Affiliation as printed
Universidad Nacional Autònoma de Mèxico, Instituto de Radioastronomìa y Astrofísica
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Affiliation as printed
Departamento de Astronomía, Universidad de Chile
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National Radio Astronomy Observatory
Affiliation as printed
National Radio Astronomy Observatory
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Affiliation as printed
I. Physikalisches Institut, Universität zu Köln
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Centre National de la Recherche Scientifique · Université Paris Cité · Commissariat à l'Énergie Atomique et aux Énergies Alternatives · Université Paris-Saclay
Affiliation as printed
Université Paris-Saclay, Université Paris-Cité, CEA, CNRS, AIM
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National Radio Astronomy Observatory
Affiliation as printed
National Radio Astronomy Observatory
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Affiliation as printed
School of Engineering and Physical Sciences, Isaac Newton Building, University of Lincoln, Brayford Pool
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Korea Astronomy and Space Science Institute · Korea University of Science and Technology
Affiliation as printed
Korea Astronomy and Space Science Institute
University of Science and Technology, Korea (UST)
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Royal Observatory · UK Astronomy Technology Centre
Affiliation as printed
UK Astronomy Technology Centre, Royal Observatory Edinburgh
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Affiliation as printed
Faculty of Physics, University of Duisburg-Essen
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Arcetri Astrophysical Observatory · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio Astrofisico di Arcetri
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Affiliation as printed
Jet Propulsion Laboratory, California Institute of Technology
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Arcetri Astrophysical Observatory · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio Astrofisico di Arcetri
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Affiliation as printed
I. Physikalisches Institut, Universität zu Köln
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National Institute for Astrophysics
Affiliation as printed
INAF-Istituto di Radioastronomia & Italian ALMA Regional Centre
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Affiliation as printed
Department of Astronomy, School of Science, The University of Tokyo
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University of Vienna · Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
Affiliation as printed
Department of Astrophysics, University of Vienna
INAF-Istituto di Astrofisica e Planetologia Spaziale
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Institute of Astronomy and Astrophysics, Academia Sinica · Academia Sinica
Affiliation as printed
Institute of Astronomy and Astrophysics, Academia Sinica
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Affiliation as printed
Dipartimento di Fisica e Astronomia, Alma Mater Studiorum – Università di Bologna
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University of Groningen · Space Research Organisation Netherlands
Affiliation as printed
Kapteyn Astronomical Institute, University of Groningen
SRON Netherlands Institute for Space Research
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University of Cologne · Zhejiang Lab
Affiliation as printed
I. Physikalisches Institut, Universität zu Köln
Zhejiang Laboratory
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Affiliation as printed
Universidad Autonoma de Chile
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Affiliation as printed
University of Connecticut, Department of Physics
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