Free Access
Issue
A&A
Volume 554, June 2013
Article Number A78
Number of page(s) 27
Section Interstellar and circumstellar matter
DOI https://doi.org/10.1051/0004-6361/201220891
Published online 11 June 2013

Online material

Appendix A: Complementary figures and tables

thumbnail Fig. A.1

Comparison of the acetone partition functions taken from the JPL database (black squares) and the approximation (blue curve) used by Friedel et al. (2005). The red curve is a fit to the JPL acetone partition functions.

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thumbnail Fig. A.2

(CH3)2CO spectra near 101 GHz toward four positions (three acetone emission peaks and HC) in the Orion BN/KL region. b)c) Spectra correspond to the channel maps shown in Fig. 1 at 101 427 MHz and 101 451 MHz, respectively. Dashed lines indicate the VLSR of 8 km s-1 and correspond to the (CH3)2CO line shown at the top of each panel.

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thumbnail Fig. A.3

(CH3)2CO spectra near 223 GHz toward four positions (three acetone emission peaks and HC) in the Orion BN/KL region. Dashed lines indicate the VLSR of 8 km s-1 and correspond to the (CH3)2CO line shown at the top of each panel. c) The dotted line indicates the (CH3)2CO 176,11 − 167,10 EA/AE lines at 223 684.6 MHz. d) The dotted line indicates the (CH3)2CO 176,11 − 167,10 EE line at 223 767.6 MHz. e) The dotted line indicates the (CH3)2CO 176,11 − 167,10 AA line at 223 850.4 MHz.

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thumbnail Fig. A.4

(CH3)2CO spectra near 225 and 229 GHz toward four positions (three acetone emission peaks and HC) in the Orion BN/KL region. Dashed lines indicate the VLSR of 8 km s-1 and correspond to the (CH3)2CO line shown at the top of each panel. c) The dotted line indicates the (CH3)2CO 221,21 − 212,20 AE/EA and 222,21 − 211,20 AE/EA lines at 229 033.8 MHz. d) The dotted line indicates the (CH3)2CO 149,6 − 138,5 EE line at 229 058.0 MHz.

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Table A.1

(CH3)2CO measurements toward Ace-1.

Table A.2

(CH3)2CO measurements toward Ace-2.

Table A.3

(CH3)2CO measurements toward Ace-3.

Table A.4

(CH3)2CO measurements toward HC.

Appendix B: Comparison with the ALMA science verification data

Basic observational parameters

The calibrated ALMA-SV data were retrieved from the ESO archive. The observations were carried out in 2012 January with 16 12-m antennas (see e.g., Zapata et al. 2012; Niederhofer et al. 2012, for more observational details). The primary beam at 223 GHz is about 28′′. Some observational parameters of the ALMA-SV and our PdBI data are listed in Table B.1. The ALMA-SV data were analyzed with the GILDAS package, and the acetone emission images were cleaned with the same Clark algorithm as for the PdBI data to minimize the effects contributed by different cleaning algorithms. The ALMA and PdBI channel maps of the acetone 177,11 − 166,10 EE line are shown in Fig. B.2, and the spectrum comparison around 223 GHz toward different positions is shown in Figs. B.3B.5. The missing flux of the ALMA-SV data is estimated to be 10−20% compared with the IRAM 30 m single-dish data (J. Cernicharo, priv. comm.) around 223 GHz, less than our PdBI data (20−50% missing flux).

Spatial comparison

Figure B.1 shows the uv coverages of the PdBI and ALMA-SV data. They are comparable, but the ALMA-SV data show a denser coverage for shorter spacings. The PdBI data have longer baselines, which result in a higher angular resolution. However, due to the few uv tracks in the −50 to 50 m domain, the PdBI observations are likely to filter out larger structures in BN/KL. This is clearly seen in Fig. B.2 in which most of the emission toward Ace-3 and in the southern part of BN/KL close to MF-1 and MF-3 is filtered out in the PdBI data. Likewise, it is important to note that the acetone emission associated with the arc-like structure in the north of HC is not resolved out by the PdBI.

Spectral comparison

Figure B.3 shows the ALMA-SV and PdBI spectra toward Ace-1 and 2. The differences between the two data sets are small for the HCOOCH3 and (CH3)2CO weak lines, but greater for the C2H5CN and SO2 strong or broad lines. It is because these lines tend to be spatially extended and are easily resolved out by the PdBI. Filtering effects are more obvious toward Ace-3 and MF-3 (Figs. B.4 and B.5) where most of the line emission, including SO2, C2H5CN, and (CH3)2CO, is filtered out.

Summary

Our PdBI spatial distribution and individual spectra are very consistent with the new ALMA-SV data toward Orion BN/KL. However, due to different uv coverages and the smaller PdBI primary beam, some extended emission is filtered out in our data, especially toward Ace-3 and in the southern part (close to MF-3) of BN/KL. It is not clear why the arc-like acetone emission close to HC has not been resolved out. One possible reason is that the acetone emission in the southern part is weaker and suffers more easily from filtering effects, as observed toward the Ace-3 region. The fully functional ALMA in the near future with a denser uv coverage and the short spacings of the Atacama Compact Array will surely help solve these issues and greatly improve the molecular line images.

Table B.1

Comparison of the ALMA-SV and PdBI observational parameters at 223.7 GHz.

thumbnail Fig. B.1

Comparison of the PdBI and ALMA-SV uv coverages.

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thumbnail Fig. B.2

Comparison of the PdBI (black) and ALMA-SV (green) channel maps of the acetone 177,11 − 166,10 EE line (Eup/k = 110.7 K) at 223 775.3 MHz. Contours run from 0.6 to 8.1 K in steps of 0.9 K, and the dashed contours represent –0.6 K. The bottom-right panel shows the integrated intensity (from 5 to 11 km s-1) in contours running from 15% to 95% in steps of 10% of their peak temperatures, and the dashed contours represent –10% of their peak temperatures. The primary beams of the ALMA-SV and PdBI data are indicated. The black square marks the center of explosion according to Zapata et al. (2009). The positions of source BN, HC, IRc6/7, and source I are marked as triangles. The positions of acetone emission peaks (Ace-1 to Ace-3) are marked as stars.

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thumbnail Fig. B.3

Comparison of the PdBI and ALMA-SV spectra near 223 GHz toward Ace-1 and Ace-2.

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thumbnail Fig. B.4

Comparison of the PdBI and ALMA-SV spectra near 223 GHz toward Ace-3 and HC.

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thumbnail Fig. B.5

Comparison of the PdBI and ALMA-SV spectra near 223 GHz toward MF-1 and MF-3. MF-3, a more extended region, suffers strong filtering effects on strong broader lines, such as SO2 and C2H5CN in the PdBI data similar to Ace-3. Some strong lines from other molecules appear at the similar frequencies to acetone in MF-1 and MF-3.

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Appendix C: Three-dimensional view of molecular structures in BN/KL

The three-dimensional visualization enables us to investigate the distributions and possible structures of different molecules in great detail. Therefore, we have prepared the three-dimensional (RA, Dec, and VLSR) images of different molecules in Orion BN/KL using the 3D Slicer program7 and the complemented procedures provided by the Astronomical Medicine Project8. Figures C.1C.4 show the different viewing angles of the C2H5CN, (CH3)2CO, and HCOOCH3 structures in BN/KL. The superposed images of these molecules were also plotted. In addition, a complementary 3D movie will be available on the A&A website.

C 2 H 5 CN

The C2H5CN line has a larger line width compared with those of (CH3)2CO and HCOOCH3 and is clearly seen in Figs. C.3 and C.4. The arc-like structure close to HC is clearer in the 3D images (e.g., Figs. C.1 and C.2). In addition, the slow outflow associated with IRc7 in the NH3 emission proposed by Goddi et al. (2011b) may actually be the two different clumps in the

SE and NW of IRc7 (see Figs. C.3 and C.4) because of the multi-component structure in the blueshifted clump revealed in the image. This complicated blueshifted clump was detected in the methyl cyanide emission (Wang et al. 2010) toward southeast of IRc7. These components may be due to the explosive outflow. However, we cannot rule out the possibility of a multi-outflow that comes from IRc7.

(CH 3 ) 2 CO

The arc-like structure is clearly seen in the acetone 3D images. It is interesting to note that the filtered-out emission toward Ace-3 is mostly centered at 8 km s-1, which creates an artificial shell-like structure in the 3D images.

HCOOCH 3

Part of the arc-like structure seen in C2H5CN and (CH3)2CO is also seen in HCOOCH3 where the HCOOCH3 emission extends from MF-3 to Ace-1 and even to the northwest of HC (Figs. C.1 and C.2). In addition, some structures close to MF-1 are seen and may be related to outflows/shocks.

 

Movie of Figures C.1−C.4 (MOV 15.8 MB) (Access here)

 

thumbnail Fig. C.1

Three-dimensional view (RA, Dec, and VLSR) of C2H5CN (red), (CH3)2CO (green), and HCOOCH3 (blue) distributions in Orion BN/KL. The C2H5CN 253,23 − 243,22 line at 223 553.6 MHz is shown in red surfaces, the (CH3)2CO 177,11 − 166,10 EE line at 223 775.3 MHz in green, and the HCOOCH3 114,8 − 103,7 A lines at 223 550.5 MHz in blue. The isothermal surfaces are plotted from 15% to 95% in steps of 20% of their peak intensities.

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thumbnail Fig. C.2

Three-dimensional view (RA, Dec, and VLSR) of C2H5CN (red), (CH3)2CO (green), and HCOOCH3 (blue) distributions in Orion BN/KL with a different viewing angle from Fig. C.1.

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thumbnail Fig. C.3

Three-dimensional view (RA, Dec, and VLSR) of C2H5CN (red), (CH3)2CO (green), and HCOOCH3 (blue) distributions in Orion BN/KL with a different viewing angle from Fig. C.1.

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thumbnail Fig. C.4

Three-dimensional view (RA, Dec, and VLSR) of C2H5CN (red), (CH3)2CO (green), and HCOOCH3 (blue) distributions in Orion BN/KL with a different viewing angle from Fig. C.1.

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© ESO, 2013

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