Synthesis Imaging of Dense Molecular Gas in the N113 H<scp>ii</scp>Region of the Large Magellanic Cloud

Wong, Tony; Whiteoak, J. B.; Ott, J.; Chin, Y.-N.; Cunningham, M. R.

doi:10.1086/504968

Cited by 23 publications

(48 citation statements)

References 39 publications

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“…This result agrees with the presence of the compact radio continuum sources detected by Brooks & Whiteoak (1997) in N113. Furthermore, the position at which the molecular lines were observed in this study lies between the two most intense continuum sources in the study of Wong et al (2006) (sources 2 and 3; IR2 and IR3 in Fig. 1-right).…”

Section: Molecular Linesmentioning

confidence: 52%

“…1 (right) that appear over the molecular concentration, marked as IR1, IR2, and IR3, are coincident with the compact radio continuum sources detected by Brooks & Whiteoak (1997) and with three YSOs (from southeast to north-west: 051325.09-692245.1, 051321.43-692241.5, and 051317.69-692225.0) catalogued by Seale et al (2012) and Carlson et al (2012). As discussed in Wong et al (2006), these sources might be young ionizing stars that affect the molecular gas and probably contribute to the birth of new stars.…”

Section: Observations and Data Reductionmentioning

confidence: 55%

“…Johansson et al 1994) is to study a low-metallicity interstellar medium (ISM), whose physical conditions may resemble those that existed in the early Milky Way and that therefore can shed light on the primeval processes of star formation. The molecular cloud associated with N113 is one of the richest in the LMC and has been studied often, presenting observations with different resolutions and sensitivities of many molecular lines (Wong et al 2006;Wang et al 2009, and references therein). However, most of the molecular lines observed towards N113 cover the frequency range 85−270 GHz (see Chin et al 1997;Wang et al 2009).…”

Section: Introductionmentioning

confidence: 99%

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ASTE observations in the 345 GHz window towards the HII region N113 of the Large Magellanic Cloud

Paron

Ortega

Cunningham

et al. 2014

A&A

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Aims. The HII region N113 is located in the central part of the Large Magellanic Cloud (LMC) with an associated molecular cloud that is very rich in molecular species. Most of the previously observed molecular lines cover the frequency range 85-270 GHz. Thus, a survey and study of lines at the 345 GHz window is required for a more complete understanding of the chemistry and excitation conditions of this region. Methods. We mapped a region of 2. 5 × 2. 5 centred at N113 using the Atacama Submillimeter Telescope Experiment in the 13 CO J = 3−2 line with an angular and spectral resolution of 22 and 0.11 km s −1 . In addition, we observed 16 molecular lines as single pointings towards its centre. Results. From the 13 CO J = 3−2 map we estimate the local thermodynamic equilibrium (LTE) and virial masses in about 1 × 10 4 and 4.5 × 10 4 M for the molecular cloud associated with N113. From the dust continuum emission at 500 μm we additionally obtain a mass of gas of 7 × 10 3 M . Towards the cloud centre we detected emission from 12 CO, 13 CO, C 18 O (3-2), HCN, HNC, HCO + , C 2 H (4-3), and CS (7-6); these are the first reported detections of the HCN, HNC, and C 2 H (4-3) lines from this region. We confirm the detection of CS (7-6), which was previously tentatively detected. From analysing the HCN, HNC, and C 2 H lines we suggest that they might be emitted from a photodissociation region (PDR). Moreover, we suggest that the chemistry involving the C 2 H lines in N113 is probably similar to that in Galactic PDRs. We analysed the HCN J = 4−3, J = 3−2, and J = 1−0 lines with the code RADEX and we conclude that we observe very high density gas, between some 10 5 and 10 7 cm −3 .

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Section: Molecular Linesmentioning

confidence: 52%

Section: Observations and Data Reductionmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

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ASTE observations in the 345 GHz window towards the HII region N113 of the Large Magellanic Cloud

Paron

Ortega

Cunningham

et al. 2014

A&A

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show abstract

“…High spatial resolution interferometry observations toward star-forming regions in the LMC have been reported from the Australia Telescope Compact Array (e.g., Wong et al 2006;Ott et al 2008;Seale et al 2012;Anderson et al 2014) and recently from the Atacama Large Millimeter/submillimeter Array (ALMA) (e.g., Indebetouw et al 2013;Fukui et al 2015). These observations resolve star-forming regions in the LMC down to the parsec-or sub-parsec-scale and investigate the physical properties of dense molecular gas.…”

Section: Introductionmentioning

confidence: 99%

The Detection of a Hot Molecular Core in the Large Magellanic Cloud With Alma

Shimonishi

Onaka

Kawamura

et al. 2016

ApJ

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We report the first detection of a hot molecular core outside our Galaxy based on radio observations with ALMA toward a high-mass young stellar object (YSO) in a nearby low metallicity galaxy, the Large Magellanic Cloud (LMC). are detected from a compact region (∼0.1 pc) associated with a high-mass YSO, ST11. The temperature of molecular gas is estimated to be higher than 100 K based on rotation diagram analysis of SO 2 and 34 SO 2 lines. The compact source size, warm gas temperature, high density, and rich molecular lines around a high-mass protostar suggest that ST11 is associated with a hot molecular core. We find that the molecular abundances of the LMC hot core are significantly different from those of Galactic hot cores. The abundances of CH 3 OH, H 2 CO, and HNCO are remarkably lower compared to Galactic hot cores by at least 1-3 orders of magnitude. We suggest that these abundances are characterized by the deficiency of molecules whose formation requires the hydrogenation of CO on grain surfaces. In contrast, NO shows a high abundance in ST11 despite the notably low abundance of nitrogen in the LMC. A multitude of SO 2 and its isotopologue line detections in ST11 imply that SO 2 can be a key molecular tracer of hot core chemistry in metal-poor environments. Furthermore, we find molecular outflows around the hot core, which is the second detection of an extragalactic protostellar outflow. In this paper, we discuss the physical and chemical characteristics of a hot molecular core in the low metallicity environment.

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“…If this is the case, our upper limit to N(NH 3 ) may be significantly underestimated. If we assume that molecular clumps within our ATCA beam have a size of 1 pc (for example, a dense clump ∼2 pc in size was observed in the LMC by Wong et al 2006), then the upper limit to N(NH 3 ) increases to a few times 10 14 cm −2 . Our upper limits for other molecular transitions are shown in Table 2.…”

Section: Abundances Of Molecular Speciesmentioning

confidence: 99%

Infrared Dark Clouds in the Small Magellanic Cloud?

Lee

Stanimirović

Ott

et al. 2009

The Astronomical Journal

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We have applied the unsharp-masking technique to the 24 μm image of the Small Magellanic Cloud (SMC), obtained with the Spitzer Space Telescope, to search for high-extinction regions. This technique has been used to locate very dense and cold interstellar clouds in the Galaxy, particularly infrared dark clouds (IRDCs). Fifty-five candidate regions of high extinction, namely, high-contrast regions (HCRs), have been identified from the generated decremental contrast image of the SMC. Most HCRs are located in the southern bar region and mainly distributed in the outskirts of CO clouds, but most likely contain a significant amount of H 2 . HCRs have a peak contrast at 24 μm of 2%-2.5% and a size of 8-14 pc. This corresponds to the size of typical and large Galactic IRDCs, but Galactic IRDCs are 2-3 times darker at 24 μm than our HCRs. To constrain the physical properties of the HCRs, we have performed NH 3 , N 2 H + , HNC, HCO + , and HCN observations toward one of the HCRs, HCR LIRS36-east, using the Australia Telescope Compact Array and the Mopra single-dish radio telescope. We did not detect any molecular line emission, however, our upper limits to the column densities of molecular species suggest that HCRs are most likely moderately dense with n ∼ 10 3 cm −3 . This volume density is in agreement with predictions for the cool atomic phase in low-metallicity environments. We suggest that HCRs may be tracing clouds at the transition from atomic to molecule-dominated medium, and could be a powerful way to study early stages of gas condensation in low-metallicity galaxies. Alternatively, if made up of dense molecular clumps < 0.5 pc in size, HCRs could be counterparts of Galactic IRDCs, and/or regions with highly unusual abundance of very small dust grains.

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Synthesis Imaging of Dense Molecular Gas in the N113 HiiRegion of the Large Magellanic Cloud

Cited by 23 publications

References 39 publications

ASTE observations in the 345 GHz window towards the HII region N113 of the Large Magellanic Cloud

ASTE observations in the 345 GHz window towards the HII region N113 of the Large Magellanic Cloud

The Detection of a Hot Molecular Core in the Large Magellanic Cloud With Alma

Infrared Dark Clouds in the Small Magellanic Cloud?

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