The APEX Large CO Heterodyne Orion Legacy Survey (ALCOHOLS)

I. Survey overview^★

¹ ESO, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany
e-mail: tstanke049@gmail.com
² Department of Astronomy, Yale University, PO Box 208101, New Haven, CT 06520-8101, USA
³ CASA, University of Colorado, Boulder, CO, USA
⁴ Dept of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
⁵ Joint ALMA Observatory, Avenida Alonso de Córdova 3107, Vitacura, Santiago, Chile
⁶ National Science Foundation, 2415 Eisenhower Avenue, Alexandria, VA 22314, USA
⁷ NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
⁸ Thüringer Landessternwarte, Sternwarte 5, 07778 Tautenburg, Germany
⁹ School of Physical Sciences, University of Kent, Canterbury CT2 7NH, UK
¹⁰ Department of Astronomy, University of Florida, PO Box 112055, USA
¹¹ Department of Astronomy, University of Massachusetts, Amherst, MA 01003, USA
¹² Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 5C2, Canada
¹³ Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
¹⁴ European Space Agency, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
¹⁵ Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA
¹⁶ National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹⁷ Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury CT2 7NH, UK
¹⁸ Departmento de Astronomía, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción, Chile
¹⁹ Nobeyama Radio Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 462-2 Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305, Japan
e-mail: k.tatematsu@nao.ac.jp
²⁰ Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721, USA
²¹ Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822, USA
e-mail: jw@hawaii.edu
²² Universidad Autonoma de Chile, Pedro de Valdivia 425, Santiago de Chile, Chile
²³ University of Southern Indiana, Evansville, IN, USA
²⁴ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA
²⁵ European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla, 19001, Santiago de Chile, Chile

Received: 1 November 2019
Accepted: 22 November 2021

Abstract

Context. The Orion molecular cloud complex harbours the nearest Giant Molecular Clouds (GMCs) and the nearest site of high-mass star formation. Its young star and protostar populations are thoroughly characterized. The region is therefore a prime target for the study of star formation.

Aims. Here, we verify the performance of the SuperCAM 64 pixel heterodyne array on the Atacama Pathfinder Experiment (APEX). We give a descriptive overview of a set of wide-field CO(3–2) spectral line cubes obtained towards the Orion GMC complex, aimed at characterizing the dynamics and structure of the extended molecular gas in diverse regions of the clouds, ranging from very active sites of clustered star formation in Orion B to comparatively quiet regions in southern Orion A. In a future publication, we will characterize the full population of protostellar outflows and their feedback over an entire GMC.

Methods. We present a 2.7 square degree (130 pc²) mapping survey in the ¹²CO(3–2) transition, obtained using SuperCAM on APEX at an angular resolution of 19′′ (7600 AU or 0.037 pc at a distance of 400 pc), covering the main sites of star formation in the Orion B cloud (L 1622, NGC 2071, NGC 2068, Ori B9, NGC 2024, and NGC 2023), and a large patch in the southern part of the L 1641 cloud in Orion A.

Results. We describe CO integrated line emission and line moment maps and position-velocity diagrams for all survey fields and discuss a few sub-regions in some detail. Evidence for expanding bubbles is seen with lines splitting into double components, often in areas of optical nebulosities, most prominently in the NGC 2024 H II region, where we argue that the bulk of the molecular gas is in the foreground of the H II region. High CO(3–2)/CO(1–0) line ratios reveal warm CO along the western edge of the Orion B cloud in the NGC 2023 & NGC 2024 region facing the IC 434 H II region. We see multiple, well separated radial velocity cloud components towards several fields and propose that L 1641-S consists of a sequence of clouds at increasingly larger distances. We find a small, seemingly spherical cloud, which we term “Cow Nebula” globule, north of NGC 2071. We confirm that we can trace high velocity line wings out to the “extremely high velocity” regime in protostellar molecular outflows for the NGC 2071-IR outflow and the NGC 2024 CO jet, and identify the protostellar dust core FIR4 (rather than FIR5) as the true driving source of the NGC 2024 monopolar outflow.