A Search for Mid‐Infrared Emission from Hot Molecular Core Candidates

Buizer, James M. De; Radomski, J. T.; Telesco, C. M.; Piña, R. K.

doi:10.1086/378949

Cited by 31 publications

(47 citation statements)

References 24 publications

(139 reference statements)

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“…The separation between a hot core region and an infrared source is reported to be smaller than ∼0.03 pc for typical Galactic sources (De Buizer et al 2003). With the present spatial resolution, the distribution of molecular lines and the dust continuum should coincide if they arise from a hot core region.…”

Section: Hot Molecular Core Associated With St11mentioning

confidence: 64%

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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Section: Hot Molecular Core Associated With St11mentioning

confidence: 64%

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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“…Many complex species, characteristic of hot cores, have been detected. From molecular line observations, the emission peak does not coincide with the HII components (Watt & Mundy 1999;De Buizer et al 2003), but is shifted to the East of the component C by ∼1 (Mookerjea et al 2007: Figure 3). This difference may arise due to the external influence of the nearby HII regions, or may reveal separate regions of chemical enrichment.…”

Section: Source Descriptionmentioning

confidence: 99%

Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data

Coutens

Vastel

Hincelin

et al. 2014

Monthly Notices of the Royal Astronomical Society

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Understanding water deuterium fractionation is important for constraining the mechanisms of water formation in interstellar clouds. Observations of HDO and H 18 2 O transitions were carried out towards the high-mass star-forming region G34.26+0.15 with the HIFI instrument onboard the Herschel Space Observatory, as well as with ground-based single-dish telescopes. Ten HDO lines and three H 18 2 O lines covering a broad range of upper energy levels (22-204 K) were detected. We used a non-LTE 1D analysis to determine the HDO/H 2 O ratio as a function of radius in the envelope. Models with different water abundance distributions were considered in order to reproduce the observed line profiles. The HDO/H 2 O ratio is found to be lower in the hot core (∼3.5 × 10 −4 -7.5 × 10 −4 ) than in the colder envelope (∼1.0 × 10 −3 -2.2 × 10 −3 ). This is the first time that a radial variation of the HDO/H 2 O ratio has been found to occur in a high-mass source. The chemical evolution of this source was modeled as a function of its radius and the observations are relatively well reproduced. The comparison between the chemical model and the observations leads to an age of ∼10 5 years after the infrared dark cloud stage.

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“…Keto et al (1992) observed a 70 mJy source at 12.5 m at the hot molecular core, below the detection limit of Campbell et al (2000). De Buizer et al (2003) set an upper limit of 21 mJy at 18 m for this source. Components A, B, C, and E appear to be a group of very young high-mass stars and a protostar.…”

Section: Introductionmentioning

confidence: 73%

“…E is only $2 00 south of C; Campbell et al (2000) modeled it as an embedded high-mass protostar. More recent observations indicate two additional weak sources near C and E (De Buizer 2001;De Buizer et al 2003). Keto et al (1992) observed a 70 mJy source at 12.5 m at the hot molecular core, below the detection limit of Campbell et al (2000).…”

Section: Introductionmentioning

confidence: 95%

High‐Resolution Far‐Infrared Observations and Models of the Star Formation Core of G34.3+0.2C

Campbell

Harvey

Lester

et al. 2004

ApJ

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High spatial resolution far-infrared (FIR) maps made on the Kuiper Airborne Observatory are presented of the extremely bright source associated with the ''cometary'' ultracompact H ii region G34.3+0.2C. The maps show sharply peaked emission at G34.3+0.2C, surrounded by extended emission of uniform temperature. Maximum entropy method deconvolutions indicate FIR core source sizes of 12 00 and 20 00 at 47 and 95 m, respectively. Radiative transfer models of centrally heated dust cloud cores are presented that match estimates of the FIR core emission at G34.3+0.2C. The FIR data and models imply that this emission is due to a compact, centrally peaked, massive core separate from the hot molecular core 2 00 east of G34.3+0.2C. In comparison to the hot molecular core, the FIR core represents a separate, more evolved core that contains a group of high-mass stars and protostars.

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A Search for Mid‐Infrared Emission from Hot Molecular Core Candidates

Cited by 31 publications

References 24 publications

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

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

Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data

High‐Resolution Far‐Infrared Observations and Models of the Star Formation Core of G34.3+0.2C

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