Molecular line contamination in the SCUBA-2 450 and 850 μm continuum data

Observations of the dust emission using millimetre/submillimetre bolometer arrays can be contaminated by molecular line flux, such as flux from 12CO. As the brightest molecular line in the submillimetre, it is important to quantify the contribution of CO flux to the dust continuum bands. Conversion factors were used to convert molecular line integrated intensities to flux detected by bolometer arrays in mJy beam−1. These factors were calculated for 12CO line integrated intensities to the SCUBA-2 850 and 450 μm bands. The conversion factors were then applied to HARP 12CO 3–2 maps of NGC 1333 in the Perseus complex and NGC 2071 and NGC 2024 in the Orion B molecular cloud complex to quantify the respective 12CO flux contribution to the 850 μm dust continuum emission. Sources with high molecular line contamination were analysed in further detail for molecular outflows and heating by nearby stars to determine the cause of the 12CO contribution. The majority of sources had a 12CO 3–2 flux contribution under 20 per cent. However, in regions of molecular outflows, the 12CO can dominate the source dust continuum (up to 79 per cent contamination) with 12CO fluxes reaching ∼68 mJy beam−1.

[1]  S. Bontemps,et al.  Herschel/HIFI observations of high-J CO lines in the NGC 1333 low-mass star-forming region , 2010, 1008.0867.

[2]  Jonathan P. Williams,et al.  A submillimetre survey of the kinematics of the Perseus molecular cloud – II. Molecular outflows , 2010, 1006.3218.

[3]  D. Ward-Thompson,et al.  The JCMT Legacy Survey of the Gould Belt: a first look at Orion B with HARP , 2009, 0908.4162.

[4]  L. E. Kristensen,et al.  APEX-CHAMP$^+$ high-J CO observations of low-mass young stellar objects - II. Distribution and origin of warm molecular gas , 2009, 0908.3446.

[5]  T. Jenness,et al.  HARP/ACSIS: a submillimetre spectral imaging system on the James Clerk Maxwell Telescope , 2009, 0907.3610.

[6]  M. Dunham,et al.  Star formation in Perseus - V. Outflows detected by HARP , 2009, 0904.1163.

[7]  Elizabeth Ledwosinska,et al.  The SCUBA Legacy Catalogues: Submillimeter-Continuum Objects Detected by SCUBA , 2008, 0801.2595.

[8]  A. Whitworth,et al.  The James Clerk Maxwell Telescope Legacy Survey of Nearby Star‐forming Regions in the Gould Belt , 2007, 0707.0169.

[9]  G. Fuller,et al.  Star formation in Perseus III. Outflows , 2007, 0706.1724.

[10]  D. Ward-Thompson,et al.  A SCUBA survey of Orion -the low-mass end of the core mass function , 2006, astro-ph/0611164.

[11]  G. Fuller,et al.  Star formation in Perseus: II. SEDs, classification and lifetimes , 2006, astro-ph/0612601.

[12]  P. Mauskopf,et al.  Bolocam Survey for 1.1 mm Dust Continuum Emission in the c2d Legacy Clouds. I. Perseus , 2005, astro-ph/0602259.

[13]  D. Johnstone,et al.  The Large- and Small-Scale Structures of Dust in the Star-forming Perseus Molecular Cloud , 2006, astro-ph/0602089.

[14]  E. F. Ladd,et al.  Star formation in Perseus - Clusters, filaments and the conditions for star formation , 2005 .

[15]  C. Wilson,et al.  High-Mass Star Formation. I. The Mass Distribution of Submillimeter Clumps in NGC 7538 , 2005, astro-ph/0503190.

[16]  L. Dunne,et al.  Revised masses of dust and gas of SCUBA Local Universe Survey far-infrared bright galaxies based on a recent CO survey , 2004, astro-ph/0401602.

[17]  M. Meyer,et al.  Low-Mass Stars and Substellar Objects in the NGC 1333 Molecular Cloud , 2003, astro-ph/0312357.

[18]  D. Johnstone,et al.  Astrochemistry of sub-millimeter sources in Orion. Studying the variations of molecular tracers with changing physical conditions , 2003, astro-ph/0310166.

[19]  F. Gueth,et al.  Dust emission from young outflows: The case of L 1157 , 2003, astro-ph/0302477.

[20]  E. Seaquist,et al.  A Multitransition CO Study of the Antennae Galaxies NGC 4038/9 , 2003, astro-ph/0301126.

[21]  P. Hennebelle,et al.  Submillimeter Studies of Prestellar Cores and Protostars: Probing the Initial Conditions for Protostellar Collapse , 2002, astro-ph/0212492.

[22]  C. Curry,et al.  SFChem 2002: Chemistry as a Diagnostic of Star Formation , 2003 .

[23]  C. Salter,et al.  Single-Dish Radio Astronomy: Techniques and Applications , 2002 .

[24]  M. Kenworthy,et al.  The Structure and Evolution of the Lagoon Nebula. I. Submillimeter Continuum and CO Line Mapping , 2002 .

[25]  D. Johnstone,et al.  A Submillimeter Dust and Gas Study of the Orion B Molecular Cloud , 2001 .

[26]  P. Andre',et al.  A SCUBA survey of the NGC 2068/2071 protoclusters , 2001 .

[27]  L. Mundy,et al.  Modelling the Submillimeter Emission from Pre-Protostellar Cores , 2001, astro-ph/0104238.

[28]  Christine D. Wilson,et al.  Large-Area Mapping at 850 Microns. II. Analysis of the Clump Distribution in the ρ Ophiuchi Molecular Cloud , 2000 .

[29]  M. Mccaughrean,et al.  Observations of a curving molecular outflow from V380 Ori-NE: further support for prompt entrainment in protostellar outflows , 2000 .

[30]  L. Mundy,et al.  Tracing the Mass during Low-Mass Star Formation. II. Modeling the Submillimeter Emission from Preprotostellar Cores , 2000, astro-ph/0006183.

[31]  P. Papadopoulos,et al.  Gas and Dust in NGC 7469: Submillimeter Imaging and CO J = 3-2 , 2000, astro-ph/0002277.

[32]  F. Motte,et al.  The initial conditions of isolated star formation — III. Millimetre continuum mapping of pre-stellar cores , 1999 .

[33]  J. Bally,et al.  JCMT/SCUBA Submillimeter Wavelength Imaging of the Integral-shaped Filament in Orion , 1998 .

[34]  J. Alves,et al.  Near-Infrared Imaging of Embedded Clusters: NGC 1333 , 1996 .

[35]  E. Serabyn,et al.  Fourier Transform Spectroscopy of the Orion Molecular Cloud Core , 1995 .

[36]  G. Blake,et al.  The molecular emission-line spectrum of IRC +10216 between 330 and 358 GHz. , 1994, The Astrophysical journal. Supplement series.

[37]  R. Hills,et al.  High-resolution molecular line observations of the core and outflow in Orion B , 1989 .