The complexity of Orion: an ALMA view

Pagani, L.; Favre, Cécile; Goldsmith, Paul F.; Bergin, Edwin A.; Snell, R. L.; Melnick, Gary J.

doi:10.1051/0004-6361/201730466

Cited by 65 publications

(77 citation statements)

References 111 publications

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“…The detection of CH 3 NH 2 towards NGC 6334I reported here and recent (tentative) detections towards the high-mass star-forming regions in Orion KL and G10.47+0.03 by Pagani et al (2017) and Ohishi et al (2017) respectively, also indicate that the species is not as uncommon in the ISM as was previously thought. This implies that future high-sensitivity, high-resolution searches for the species are likely to yield additional detections of the formerly so elusive molecule.…”

Section: Discussionsupporting

confidence: 83%

“…The detection of CH 3 NH 2 in the hot cores of NGC 6334I presented here, combined with recent (tentative) detections by Pagani et al (2017) towards Orion KL and Ohishi et al (2017) towards a few high-mass objects, indicate that this molecule is more common and abundant than previously thought (see for example the upper limits on the species presented by Ligterink et al 2015). In this case, the 'lacking' CH 3 NH 2 -detections are more likely explained by observational biases, for example the large partition function of CH 3 NH 2 resulting in relatively weaker transitions of this species as compared with, for example, NH 2 CHO, rather than actual chemical variations between objects.…”

Section: Methylamine Towards Ngc 6334isupporting

confidence: 79%

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Methylamine and other simple N-bearing species in the hot cores NGC 6334I MM1–3

Bøgelund

McGuire

Hogerheijde

et al. 2019

A&A

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Context. In the search for the building blocks of life, nitrogen-bearing molecules are of particular interest since nitrogen-containing bonds are essential for the linking of amino acids and ultimately the formation of larger biological structures. The elusive molecule methylamine (CH 3 NH 2 ) is thought to be a key pre-biotic species but has so far only been securely detected in the giant molecular cloud Sagittarius B2. Aims. We identify CH 3 NH 2 and other simple nitrogen-bearing species involved in the synthesis of biologically relevant molecules towards three hot cores associated with the high-mass star-forming region NGC 6334I, located at a distance of 1.3 kpc. Column density ratios are derived in order to investigate the relevance of the individual species as precursors of biotic molecules. Methods. High sensitivity, high angular and spectral resolution observations obtained with the Atacama Large Millimeter/submillimeter Array were used to study transitions of CH 3 NH 2 , CH 2 NH, NH 2 CHO, and the 13 C-and 15 N-methyl cyanide (CH 3 CN) isotopologues, detected towards NGC 6334I. Column densities are derived for each species assuming local thermodynamic equilibrium and excitation temperatures in the range 220-340 K for CH 3 NH 2 , 70-110 K for the CH 3 CN isotopologues and 120-215 K for NH 2 CHO and CH 2 NH. Results. We report the first detections of CH 3 NH 2 towards NGC 6334I with column density ratios with respect to CH 3 OH of 5.9ˆ10´3, 1.5ˆ10´3 and 5.4ˆ10´4 for the three hot cores MM1, MM2, and MM3, respectively. These values are slightly lower than the values derived for Sagittarius B2 but higher by more than order of magnitude as compared with the values derived for the low-mass protostar IRAS 16293-2422B. The column density ratios of NH 2 CHO, 13 CH 3 CN, and CH 3 C 15 N with respect to CH 3 OH are (1.5-1.9)ˆ10´4, (1.0-4.6)ˆ10´3 and (1.7-3.0)ˆ10´3 respectively. Lower limits of 5.2, 1.2, and 3.0 are reported for the CH 3 NH 2 to CH 2 NH column density ratio for MM1, MM2, and MM3 respectively. These limits are largely consistent with the values derived for Sagittarius B2 and higher than those for IRAS 16293-2422B. Conclusions. The detections of CH 3 NH 2 in the hot cores of NGC 6334I hint that CH 3 NH 2 is generally common in the interstellar medium, albeit that high-sensitivity observations are essential for the detection of the species. The good agreement between model predictions of CH 3 NH 2 ratios and the observations towards NGC 6334I indicate a main formation pathway via radical recombination on grain surfaces. This process may be stimulated further by high grain temperatures allowing a lager degree of radical mobility. Further observations with ALMA will help evaluate the degree to which CH 3 NH 2 chemistry depends on the temperature of the grains in high-and low-mass regions respectively.

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Section: Discussionsupporting

confidence: 83%

Section: Methylamine Towards Ngc 6334isupporting

confidence: 79%

Methylamine and other simple N-bearing species in the hot cores NGC 6334I MM1–3

Bøgelund

McGuire

Hogerheijde

et al. 2019

A&A

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“…These and other vibrationally excited lines with comparable energy levels have been observed in other astrophysical environments, such as carbon stars (Izumiura et al 1987;Bieging 2001), hot cores (Esplugues et al 2013;Pagani et al 2017), or ultraluminous infrared galaxies (Imanishi & Nakanishi 2013;Imanishi et al 2016). In all those cases, however, the intensity of the vibrationally excited lines remains as a small fraction of the ground level lines.…”

Section: Line Absorptionssupporting

confidence: 56%

The peculiar chemistry of the inner ejecta of Eta Carina

Bordiu

Rizzo

2019

Monthly Notices of the Royal Astronomical Society

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We investigated continuum and molecular line emission of four species (CO, HCN, H 13 CN, and HCO + ) at 0.8 mm in the inner region around η Car, using ALMA archival observations at a resolution better than 0.2 arcsec. We report the discovery of an asymmetric extended structure northwest of the star, independent from the continuum point source. The structure is only traced by continuum and HCO + , and not detected in the other lines. Kinematics of this structure reveal that the HCO + gas likely arises from ejecta expelled in the 1890s eruption. The ejecta is propagating outward within the cavity produced by the current wind-wind interaction of η Car A and its companion. Chemical analysis of the ejecta reveals an apparent lack of CO and nitrogen-bearing species. We explore possible explanations for this peculiar chemistry, that differentiates this structure from the ejecta of the Great Eruption, rich in HCN and H 13 CN. We also report an absorption component near the continuum point source, only traced by HCN and H 13 CN in their vibrational-ground and vibrationally-excited states. This absorbing gas is attributed to a hot bullet of N-enriched material expelled at a projected velocity of 40 km s −1 .

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“…The Orion Kleinmann-Low Nebula (Orion KL) is a good site for investigating the physical and chemical evolution of high-mass star-forming regions. It is the closest high-mass star-forming region (437 ± 19 pc; Hirota et al 2007), and it exhibits rich molecular line emission at the (sub)millimeter wavelengths (Blake et al 1987;Tercero et al 2010;Crockett et al 2014;Feng et al 2015;Frayer et al 2015;Pagani et al 2017;Peng et al 2017Peng et al , 2019. Observationally, this region is composed of four major components, the hot core, the compact ridge, the plateau, and the extended ridge, which are spatially and kinematically different (Blake et al 1987;Schilke et al 2001;Tercero et al 2010;Crockett et al 2014, e.g.,).…”

Section: Introductionmentioning

confidence: 96%

Sulfur-bearing Molecules in Orion KL

Luo

Feng

et al. 2019

ApJ

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We present an observational study of the sulfur (S)-bearing species towards Orion KL at 1.3 mm by combining ALMA and IRAM-30 m single-dish data. At a linear resolution of ∼800 au and a velocity resolution of 1 km s −1 , we have identified 79 molecular lines from 6 S-bearing species. In these S-bearing species, we found a clear dichotomy between carbon-sulfur compounds and carbonfree S-bearing species in various characteristics, e.g., line profiles, spatial morphology, and molecular abundances with respect to H 2 . Lines from the carbon-sulfur compounds (i.e., OCS, 13 CS, H 2 CS) exhibit spatial distributions concentrated around the continuum peaks and extended to the south ridge. The full width at half maximum (FWHM) linewidth of these molecular lines is in the range of 2 ∼ 11 km s −1 . The molecular abundances of OCS and H 2 CS decrease slightly from the cold (∼68 K) to the hot (∼176 K) regions. In contrast, lines from the carbon-free S-bearing species (i.e., SO 2 , 34 SO, H 2 S) are spatially more extended to the northeast of mm4, exhibiting broader FWHM linewidths (15 ∼ 26 km s −1 ). The molecular abundances of carbon-free S-bearing species increase by over an order of magnitude as the temperature increase from 50 K to 100 K. In particular, 34 SO/ 34 SO 2 and OCS/SO 2 are enhanced from the warmer regions (>100 K) to the colder regions (∼50 K). Such enhancements are consistent with the transformation of SO 2 at warmer regions and the influence of shocks.

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The complexity of Orion: an ALMA view

Cited by 65 publications

References 111 publications

Methylamine and other simple N-bearing species in the hot cores NGC 6334I MM1–3

Methylamine and other simple N-bearing species in the hot cores NGC 6334I MM1–3

The peculiar chemistry of the inner ejecta of Eta Carina

Sulfur-bearing Molecules in Orion KL

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