A Three‐Position Spectral Line Survey of Sagittarius B2 between 218 and 263 GHz. I. The Observational Data

Nummelin, A.; Bergman, P.; Hjalmarson, Å.; Friberg, Per; Irvine, William M.; Millar, T. J.; Ohishi, Masatoshi; Saito, Shuji

doi:10.1086/313126

Cited by 149 publications

(175 citation statements)

References 27 publications

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“…have value comparable to the present survey. SgrB2 appears as a noticeable exception, displaying significantly higher line densities, as high as 100 lines per GHz in the 3 mm range observed with IRAM (Belloche et al 2007) or 40 lines per GHz in the 1 mm range observed with SEST (Nummelin et al 1998(Nummelin et al , 2000. Interestingly, the slope of -0.9 that we observe for the cumulative number of lines versus flux threshold is identical to the slopes observed by Schilke et al (2001), White et al (2003), and Comito et al (2005) in their submillimeter surveys of Orion-KL.…”

Section: Comparison With Previous Surveysmentioning

confidence: 87%

“…They have covered the whole range of frequencies reachable from the ground, from the 3 mm range observed with IRAM, SEST, NRAO, or JCMT to the submillimeter windows observable with the CSO and JCMT (MacDonald et al 1996;Schilke et al 1997;Helmich & van Dishoeck 1997;Nummelin et al 1998;Thompson & MacDonald 1999;Kim et al 2000;Nummelin et al 2000;Lee et al 2001;Schilke et al 2001;White et al 2003;Comito et al 2005;Kim et al 2006;Belloche et al 2007;Olofsson et al 2007;Tercero et al 2010). The line densities usually range from 10 to 20 lines per GHz, i.e.…”

Section: Comparison With Previous Surveysmentioning

confidence: 99%

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TIMASSS: the IRAS 16293-2422 millimeter and submillimeter spectral survey

Caux

Kahane

Castets

et al. 2011

A&A

164

220

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Context. Unbiased spectral surveys are powerful tools to study the chemistry and the physics of star forming regions, because they can provide a complete census of the molecular content and the observed lines probe the physical structure of the source. Aims. While unbiased surveys at the millimeter and sub-millimeter wavelengths observable from ground-based telescopes have previously been performed towards several high mass protostars, very little exists on low mass protostars, which are believed to resemble our own Sun's progenitor. To help fill up this gap in our understanding, we carried out a complete spectral survey of the bands at 3, 2, 1, and 0.9 mm towards the solar type protostar IRAS 16293-2422. Methods. The observations covered a range of about 200 GHz and were obtained with the IRAM-30 m and JCMT-15 m telescopes during about 300 h of observations. Particular attention was devoted to the inter-calibration of the acquired spectra with previous observations. All the lines detected with more than 3σ confidence-interval certainty and free from obvious blending effects were fitted with Gaussians to estimate their basic kinematic properties. Results. More than 4000 lines were detected (with σ ≥ 3) and identified, yielding a line density of approximatively 20 lines per GHz, comparable to previous surveys in massive hot cores. The vast majority (about two-thirds) of the lines are weak and produced by complex organic molecules. The analysis of the profiles of more than 1000 lines belonging to 70 species firmly establishes the presence of two distinct velocity components associated with the two objects, A and B, forming the IRAS 16293-2422 binary system. In the source A, the line widths of several species increase with the upper level energy of the transition, a behavior compatible with gas infalling towards a ∼1 M object. The source B, which does not show this effect, might have a much lower central mass of ∼0.1 M . The difference in the rest velocities of both objects is consistent with the hypothesis that the source B rotates around the source A. Conclusions. This spectral survey, although obtained with single-dish telescopes at a low spatial resolution, allows us to separate the emission from two different components, thanks to the large number of lines detected. The data of the survey are public and can be retrieved on the TIMASSS web site .

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Section: Comparison With Previous Surveysmentioning

confidence: 87%

Section: Comparison With Previous Surveysmentioning

confidence: 99%

TIMASSS: the IRAS 16293-2422 millimeter and submillimeter spectral survey

Caux

Kahane

Castets

et al. 2011

A&A

164

220

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“…Sutton et al (1985) detected lines of both isotopomers with one 13 C in a line survey of Orion. More recently, CH 2 DCN has been detected in two hot core sources (Gerin et al 1992), and some lines of CH 3 C 15 N were detected in a line survey of Sagittarius B2 (Nummelin et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies

Müller¹,

Drouin

Pearson

2009

A&A

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Context. Methyl cyanide is an important trace molecule in star-forming regions. It is one of the more common molecules used to derive kinetic temperatures in such sources. Aims. As preparatory work for Herschel, SOFIA, and in particular ALMA we want to improve the rest frequencies of the main as well as minor isotopologs of methyl cyanide. Methods. The laboratory rotational spectrum of methyl cyanide in natural isotopic composition has been recorded up to 1.63 THz. Results. Transitions with good signal-to-noise ratio could be identified for CH 3 CN, 13 CH 3 CN, CH 13 3 CN, CH 3 C 15 N, CH 2 DCN, and 13 CH 13 3 CN in their ground vibrational states up to about 1.2 THz. The main isotopic species could be identified even in the highest frequency spectral recordings around 1.6 THz. The highest J quantum numbers included in the fit are 64 for 13 CH 13 3 CN and 89 for the main isotopic species. Greatly improved spectroscopic parameters have been obtained by fitting the present data together with previously reported transition frequencies.Conclusions. The present data will be helpful to identify isotopologs of methyl cyanide in the higher frequency bands of instruments such as the recently launched Herschel satellite, the upcoming airplane mission SOFIA or the radio telescope array ALMA.

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“…Hydrogen cyanide ( HCN ), methyl cyanide (CH 3 CN ), vinyl cyanide (CH 2 CHCN ), and ethyl cyanide (CH 3 CH 2 CN ) all have large abundances, are easily detectable in a number of interstellar environments, and are readily seen in the spectra of several molecular line surveys (e.g., Friedel et al 2004;Nummelin et al 1998). However, while there have been detections of HNC in interstellar and cometary environments, there has been no confirmed detection of the isocyanides CH 3 NC, CH 2 CHNC, and CH 3 CH 2 NC.…”

Section: Introductionmentioning

confidence: 99%

Interstellar Isomers: The Importance of Bonding Energy Differences

Remijan

Hollis

Lovas

et al. 2005

ApJ

101

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We present strong detections of methyl cyanide (CH 3 CN), vinyl cyanide (CH 2 CHCN), ethyl cyanide (CH 3 CH 2 CN), and cyanodiacetylene (HC 4 CN) molecules with the Green Bank Telescope (GBT) toward the Sgr B2(N) molecular cloud. Attempts to detect the corresponding isocyanide isomers were only successful in the case of methyl isocyanide (CH 3 NC ) for its J K ¼ 1 0 0 0 transition, which is the first interstellar report of this line. To determine the spatial distribution of CH 3 NC, we used archival Berkeley-Illinois-Maryland Association ( BIMA) array data for the J K ¼ 4 K 3 K (K ¼ 0 3) transitions, but no emission was detected. From ab initio calculations, the bonding energy difference between the cyanide and isocyanide molecules is >8500 cm À1 (>12,000 K ). Thus, cyanides are the more stable isomers and would likely be formed more preferentially over their isocyanide counterparts. That we detect CH 3 NC emission with a single antenna (Gaussian beam size B ¼ 1723 arcsec 2 ) but not with an interferometer ( B ¼ 192 arcsec 2 ) strongly suggests that CH 3 NC has a widespread spatial distribution toward the Sgr B2( N ) region. Other investigators have shown that CH 3 CN is present both in the LMH hot core of Sgr B2( N ) and in the surrounding medium, while we have shown that CH 3 NC appears to be deficient in the LMH hot core. Thus, largescale, nonthermal processes in the surrounding medium may account for the conversion of CH 3 CN to CH 3 NC, while the LMH hot core, which is dominated by thermal processes, does not produce a significant amount of CH 3 NC. Ice analog experiments by other investigators have shown that radiation bombardment of CH 3 CN can produce CH 3 NC, thus supporting our observations. We conclude that isomers separated by such large bonding energy differences are distributed in different interstellar environments, making the evaluation of column density ratios between such isomers irrelevant unless it can be independently shown that these species are cospatial.

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A Three‐Position Spectral Line Survey of Sagittarius B2 between 218 and 263 GHz. I. The Observational Data

Cited by 149 publications

References 27 publications

TIMASSS: the IRAS 16293-2422 millimeter and submillimeter spectral survey

TIMASSS: the IRAS 16293-2422 millimeter and submillimeter spectral survey

Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies

Interstellar Isomers: The Importance of Bonding Energy Differences

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A Three‐Position Spectral Line Survey of Sagittarius B2 between 218 and 263 GHz. I. The Observational Data

Cited by 149 publications

References 27 publications

TIMASSS: the IRAS 16293-2422 millimeter and submillimeter spectral survey

TIMASSS: the IRAS 16293-2422 millimeter and submillimeter spectral survey

Rotational spectra of isotopic species of methyl cyanide, CH3CN, in their ground vibrational states up to terahertz frequencies

Interstellar Isomers: The Importance of Bonding Energy Differences

Contact Info

Product

Resources

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Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies