Tracing the Bipolar Outflow From Orion Source I

et al. 2013

A&A

Context. We present a study of the sulfur-bearing species detected in a line confusion-limited survey towards Orion KL performed with the IRAM 30-m telescope in the frequency range 80−281 GHz. Aims. This study is part of an analysis of the line survey divided into families of molecules. Our aim is to derive accurate physical conditions, as well as molecular abundances, in the different components of Orion KL from observed SO and SO 2 lines. Methods. As a starting point, we assumed local thermodynamic equilibrium (LTE) conditions obtain rotational temperatures. We then used a radiative transfer model, assuming either LVG or LTE excitation to derive column densities of these molecules in the different components of Orion KL. = 1 and for several undetected sulfur-bearing species. In addition, we present 2 × 2 maps around Orion IRc2 of SO 2 transitions with energies from 19 to 131 K and also maps with four transitions of SO, 34 SO, and 34 SO 2 . We observe an elongation of the gas along the NE-SW direction. An unexpected emission peak appears at 20.5 km s −1 in most lines of SO and SO 2 . A study of the spatial distribution of this emission feature shows that it is a new component of a few arcseconds (∼5 ) in diameter, which lies ∼4 west of IRc2. We suggest the emission from this feature is related to shocks associated to the BN object. Conclusions. The highest column densities for SO and SO 2 are found in the high-velocity plateau (a region dominated by shocks) and in the hot core. These values are up to three orders of magnitude higher than the results for the ridge components. We also find high column densities for their isotopologues in both components. Therefore, we conclude that SO and SO 2 are good tracers, not only of regions affected by shocks, but also of regions with warm dense gas (hot cores).

Section: × 2 Maps Around Irc2supporting

confidence: 92%

A line confusion-limited millimeter survey of Orion KL

Esplugues

Tercero

et al. 2013

A&A

“…In fact, source I coincides with the centroid of the SiO maser distribution (Plambeck et al 2009). These high densities and the high dust extinction (A V ∼ 1000) obscure the innermost regions in the near-and mid-IR.…”

Section: Introductionmentioning

confidence: 80%

Combined IRAM andHerschel/HIFI study of cyano(di)acetylene in Orion KL: tentative detection of DC₃N

Esplugues

Viti

et al. 2013

A&A

Context. We present a study of cyanoacetylene (HC 3 N) and cyanodiacetylene (HC 5 N) in Orion KL using observations from two line surveys performed with the IRAM 30-m telescope and the HIFI instrument onboard the Herschel telescope. The frequency ranges covered are 80−280 GHz and 480−1906 GHz. Aims. This study (divided by families of molecules) is part of a global analysis of the physical conditions of Orion KL and the molecular abundances in the different components of this cloud. Methods. We modeled the observed lines of HC 3 N, HC 5 N, their isotopologues (including DC 3 N), and vibrational modes using a non-local thermodynamic equilibrium (non-LTE) radiative transfer code. In addition, to investigate the chemical origin of HC 3 N and DC 3 N in Orion KL, we used a time-dependent chemical model. Results. We detect 40 lines of the ground vibrational state of HC 3 N and 68 lines of its 13 C isotopologues. We also detect 297 lines of six vibrational modes of this molecule (ν 7 , 2ν 7 , 3ν 7 , ν 6 , ν 5 , and ν 6 +ν 7 ) and 35 rotational lines of the ground vibrational state of HC 5 N. We report the first tentative detection of DC 3 N in a giant molecular cloud. We have obtained a DC 3 N/HC 3 N abundance ratio of 0.015 ± 0.009, similar to typical D/H ratios of cold dark clouds. We provide column densities for all species and derived isotopic and molecular abundances. We also made a 2 × 2 map around Orion IRc2 and present maps of the HC 3 N lines with energies from 34 to 154 K and of the HC 3 N vibrational modes ν 6 and ν 7 with energies between 354 and 872 K. In addition, a comparison of our results for HC 3 N with those in other clouds has allowed us to derive correlations between the column density, the FWHM, the mass, and the luminosity of the clouds. Conclusions. The high column densities of HC 3 N obtained in the hot core, in particular of the ground vibrational state and the vibrational mode ν 7 , make this molecule an excellent tracer of hot and dense gas. In addition, the wide frequency range covered reveals the need to consider a temperature and density gradient in the hot core to obtain better line fits. The high D/H ratio (similar to that obtained in cold clouds) that we derive suggests a deuterium enrichment. Our chemical models indicate that the possible deuterated HC 3 N in Orion KL is formed during the gas-phase. This fact provides new hints concerning the processes leading to deuteration.

“…5 south of IRc2) as the source coinciding with the centroid of the SiO maser distribution (Plambeck et al 2009;Zapata et al 2009a;Goddi et al 2009b). They also detected the radio continuum emission of IR source n, suggesting this source as another precursor of the largescale phenomena.…”

Section: Introductionmentioning

confidence: 91%

“…Thus, the core of Orion KL contains the compact HII regions I and n (in addition to BN, which was resolved with high resolution at 7 mm by Rodríguez et al 2009), which appear to be receding from a common point, an originally massive stellar system that disintegrated 500 years ago (Gómez et al 2005;Zapata et al 2009b). Finally, submm aperture synthesis line surveys provided the spatial location and extent of many molecular species (Blake et al 1996;Wright et al 1996;Liu et al 2002;Beuther et al 2005;Goddi et al 2009b;Plambeck et al 2009;Zapata et al 2009a).…”

Section: Introductionmentioning

confidence: 99%

A line confusion limited millimeter survey of Orion KL I. Sulfur carbon chains

Tercero

Pardo

et al. 2010

A&A

154

250

We perform a sensitive (line confusion limited), single-side band spectral survey towards Orion KL with the IRAM 30 m telescope, covering the following frequency ranges: 80−115.5 GHz, 130−178 GHz, and 197−281 GHz. We detect more than 14 400 spectral features of which 10 040 have been identified up to date and attributed to 43 different molecules, including 148 isotopologues and lines from vibrationally excited states. In this paper, we focus on the study of OCS, HCS + , H 2 CS, CS, CCS, C 3 S, and their isotopologues. In addition, we map the OCS J = 18−17 line and complete complementary observations of several OCS lines at selected positions around Orion IRc2 (the position selected for the survey). We report the first detection of OCS ν 2 = 1 and ν 3 = 1 vibrationally excited states in space and the first detection of C 3 S in warm clouds. Most of CCS, and almost all C 3 S, line emission arises from the hot core indicating an enhancement of their abundances in warm and dense gas. Column densities and isotopic ratios have been calculated using a large velocity gradient (LVG) excitation and radiative transfer code (for the low density gas components) and a local thermal equilibrium (LTE) code (appropriate for the warm and dense hot core component), which takes into account the different cloud components known to exist towards Orion KL, the extended ridge, compact ridge, plateau, and hot core. The vibrational temperature derived from OCS ν 2 = 1 and ν 3 = 1 levels is 210 K, similar to the gas kinetic temperature in the hot core. These OCS high energy levels are probably pumped by absorption of IR dust photons. We derive an upper limit to the OC 3 S, H 2 CCS, HNCS, HOCS + , and NCS column densities. Finally, we discuss the D/H abundance ratio and infer the following isotopic abundances: 12 C/ 13 C = 45 ± 20, 32 S/ 34 S = 20 ± 6, 32 S/ 33 S = 75 ± 29, and 16 O/ 18 O = 250 ± 135.