A 1.3 cm line survey toward IRC +10216

Gong, Y.; Henkel, C.; Spezzano, S.; Thorwirth, Sven; Menten, K. M.; Wyrowski, F.; Mao, Rihua; Klein, Bernd

doi:10.1051/0004-6361/201424819

Cited by 33 publications

(98 citation statements)

References 77 publications

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“…The peak intensity is estimated to be about 0.012 Jy, so its non-detection can be expected. On the other hand, we do not detect HC 7 N and HC 9 N transitions in this band which are detected in large numbers toward TMC-1 and IRC +10216 (Kaifu et al 2004;Gong et al 2015). HCN υ 2 = 1 direct l-type transitions detected originally in the protoplanetary nebula CRL 618 (Thorwirth et al 2003) and selected high-mass star-forming regions (Thorwirth 2001), as well as the prototypical starburst galaxy Arp 220 (Salter et al 2008), are also not detected in this survey.…”

Section: Sulfur-bearing Molecules So 2 and Ocscontrasting

confidence: 77%

“…However, despite the long history of powerful large radio telescopes, only very few unbiased frequency surveys have been conducted in the centimeter wave regime. Spectroscopic features that are A&A 581, A48 (2015) TMC-1 from 9 to 50 GHz with the Nobeyama 45 m telescope; Gong et al (2015) measured IRC +10216 from 17.8 to 26.3 GHz with the Effelsberg 100 m telescope finding 23 new transitions from species detected previously; and Remijan et al (2008a) surveyed Sgr B2 near the Galactic center with the Green Bank Telescope (GBT) in the course of their GBT PRIMOS project 1 which led to detections of complex organic molecules, such as CH 2 CHCHO (propenal), CH 3 CH 2 CHO (propanal), and CNCHO (cyanoformaldehyde; Hollis et al 2004;Remijan et al 2008a). They have shown that the centimeter wave range of the electromagnetic spectrum has an enormous potential for detecting new molecules and new transitions.…”

Section: Introductionmentioning

confidence: 99%

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A 1.3 cm line survey toward Orion KL

Gong

Henkel

Thorwirth

et al. 2015

A&A

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Context. The nearby Orion Kleinmann-Low nebula is one of the most prolific sources of molecular line emission. It has served as a benchmark for spectral line searches throughout the (sub)millimeter regime. Aims. The main goal is to systematically study the spectral characteristics of Orion KL in the λ ∼ 1.3 cm band. Methods. We carried out a spectral line survey with the Effelsberg-100 m telescope toward Orion KL. It covers the frequency range between 17.9 GHz and 26.2 GHz, i.e., the radio "K band". We also examined ALMA maps to address the spatial origin of molecules detected by our 1.3 cm line survey. Results. In Orion KL, we find 261 spectral lines, yielding an average line density of about 32 spectral features per GHz above 3σ (a typical value of 3σ is 15 mJy). The identified lines include 164 radio recombination lines (RRLs) and 97 molecular lines. The RRLs, from hydrogen, helium, and carbon, stem from the ionized material of the Orion Nebula, part of which is covered by our beam. The molecular lines are assigned to 13 different molecular species including rare isotopologues. A total of 23 molecular transitions from species known to exist in Orion KL are detected for the first time in the interstellar medium. Non-metastable (J > K) 15 NH 3 transitions are detected in Orion KL for the first time. Based on the velocity information of detected lines and the ALMA images, the spatial origins of molecular emission are constrained and discussed. A narrow feature is found in SO 2 (8 1,7 −7 2,6 ), but not in other SO 2 transitions, possibly suggesting the presence of a maser line. Column densities and fractional abundances relative to H 2 are estimated for 12 molecules with local thermodynamic equilibrium (LTE) methods. Rotational diagrams of non-metastable 14 NH 3 transitions with J = K + 1 to J = K + 4 yield different results; metastable (J = K) 15 NH 3 is found to have a higher excitation temperature than non-metastable 15 NH 3 , also indicating that they may trace different regions. Elemental and isotopic abundance ratios are also estimated: He/H = (8.7 ± 0.7)% derived from the ratios between helium RRLs and hydrogen RRLs; 12 C/ 13 C = 63 ± 17 from 12 CH 3 OH/ 13 CH 3 OH; 14 N/ 15 N =100 ± 51 from 14 NH 3 / 15 NH 3 ; and D/H = (8.3 ± 4.5) × 10 −3 from NH 2 D/NH 3 . The dispersion of the He/H ratios derived from Hα/Heα pairs to Hδ/Heδ pairs is very small, which is consistent with theoretical predictions that the departure coefficients b n factors for hydrogen and helium are nearly identical. Based on a non-LTE code that neglects excitation by the infrared radiation field and a likelihood analysis, we find that the denser regions have lower kinetic temperature, which favors an external heating of the hot core.

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Section: Sulfur-bearing Molecules So 2 and Ocscontrasting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

A 1.3 cm line survey toward Orion KL

Gong

Henkel

Thorwirth

et al. 2015

A&A

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“…The NH 3 (2,2)/(1,1) ratio is sensitive to gas temperatures T kin < 50 K (Mangum et al 2013a;Gong et al 2015a), which is similar to the kinetic temperature range that the para-H 2 CO (3-2) ratio is most sensitive to . The NH 3 lines have lower effective excitation densities than the para-H 2 CO (3-2) transitions by a few orders of magnitude, n eff (NH 3 (1,1)) ∼ 10…”

Section: Comparison Of Temperatures Derived From H 2 Co and Other Gasmentioning

confidence: 72%

Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde

Tang

Henkel

Menten

et al. 2017

A&A

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We mapped the kinetic temperature structure of the Orion molecular cloud 1 (OMC-1) with para-H 2 CO (J KaKc = 3 03 -2 02 , 3 22 -2 21 , and 3 21 -2 20 ) using the APEX 12 m telescope. This is compared with the temperatures derived from the ratio of the NH 3 (2,2)/(1,1) inversion lines and the dust emission. Using the RADEX non-LTE model, we derive the gas kinetic temperature modeling the measured averaged line ratios of para-H 2 CO 3 22 -2 21 /3 03 -2 02 and 3 21 -2 20 /3 03 -2 02 . The gas kinetic temperatures derived from the para-H 2 CO line ratios are warm, ranging from 30 to >200 K with an average of 62 ± 2 K at a spatial density of 10 5 cm −3 . These temperatures are higher than those obtained from NH 3 (2,2)/(1,1) and CH 3 CCH (6-5) in the OMC-1 region. The gas kinetic temperatures derived from para-H 2 CO agree with those obtained from warm dust components measured in the mid infrared (MIR), which indicates that the para-H 2 CO (3-2) ratios trace dense and warm gas. The cold dust components measured in the far infrared (FIR) are consistent with those measured with NH 3 (2,2)/(1,1) and the CH 3 CCH (6-5) line series. With dust at MIR wavelengths and para-H 2 CO (3-2) on one side and dust at FIR wavelengths, NH 3 (2,2)/(1,1), and CH 3 CCH (6-5) on the other, dust and gas temperatures appear to be equivalent in the dense gas (n(H 2 ) 10 4 cm −3 ) of the OMC-1 region, but provide a bimodal distribution, one more directly related to star formation than the other. The non-thermal velocity dispersions of para-H 2 CO are positively correlated with the gas kinetic temperatures in regions of strong non-thermal motion (Mach number 2.5) of the OMC-1, implying that the higher temperature traced by para-H 2 CO is related to turbulence on a ∼0.06 pc scale. Combining the temperature measurements with para-H 2 CO and NH 3 (2,2)/(1,1) line ratios, we find direct evidence for the dense gas along the northern part of the OMC-1 10 km s −1 filament heated by radiation from the central Orion nebula.

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“…IRC +10216 (or CW Leo) is an archetypal carbon star that is very rich in molecular line emission (see the most recent examples in He et al 2008;Tenenbaum et al 2010a;Cernicharo et al 2010;Neufeld et al 2011;Patel et al 2011;Decin et al 2015;Gong et al 2015, among others) and serves as a benchmark for molecular line studies in circumstellar envelopes. Most of the weak maser lines in carbon stars were also discovered in this object.…”

Section: Introductionmentioning

confidence: 99%

Monitor Variability of Millimeter Lines in IRC+10216

Dinh-V-Trung

Hasegawa

2017

ApJ

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A single dish monitoring of millimeter maser lines SiS J=14-13 and HCN ν 2 = 1 f J=3-2 and several other rotational lines is reported for the archetypal carbon star IRC +10216. Relative line strength variations of 5%∼30% are found for eight molecular line features with respect to selected reference lines. Definite line-shape variation is found in limited velocity intervals of the SiS and HCN line profiles. The asymmetrical line profiles of the two lines are mainly due to the varying components. Their dominant varying components of the line profiles have similar periods and phases as the IR light variation, although both quantities show some degree of velocity dependence; there is also variability asymmetry between the blue and red line wings of both lines. Combining the velocities and amplitudes with a wind velocity model, we suggest that the line profile variations are due to SiS and HCN masing lines emanating from the wind acceleration zone. The possible link of the variabilities to thermal, dynamical and/or chemical processes within or under this region is also discussed.

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A 1.3 cm line survey toward IRC +10216

Cited by 33 publications

References 77 publications

A 1.3 cm line survey toward Orion KL

A 1.3 cm line survey toward Orion KL

Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde

Monitor Variability of Millimeter Lines in IRC+10216

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