EDP Sciences
Free Access
Issue
A&A
Volume 553, May 2013
Article Number A125
Number of page(s) 29
Section Interstellar and circumstellar matter
DOI https://doi.org/10.1051/0004-6361/201220472
Published online 23 May 2013

Online material

Appendix A: Characterisation of the HIFI data

thumbnail Fig. A.1

12CO J = 10–9 spectra for low- and intermediate-mass YSOs. The green line represents the baseline level and the pink Gaussian profile the broad velocity component for those sources for which a two Gaussian decomposition has been performed. All the spectra have been shifted to zero velocity. The numbers indicate where the spectra have been scaled for greater visibility.

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Table A.1

Observed and fitted properties of the 12CO J = 10–9 line profiles.

The main characteristics of the HIFI data are presented in this appendix, together with the spectra. The description of the observed lines focuses first on 12CO J = 10–9 (Sect. A.1), where the main characteristics for the low-, intermediate- and high-mass sources are listed in that order. Next we discuss the 13CO J = 10–9 spectra (Sect. A.2), following the same structure, and finally all observed C18O lines (Sect. A.3) are presented.

Appendix A.1: 12CO J = 10–9 line profiles

The 12CO J = 10–9 line was observed for the entire sample of low- and intermediate-mass YSOs and for one high-mass object (W3-IRS5). All the observed sources were detected, and the emission profiles are the strongest and broadest among the targeted HIFI CO lines (see Fig. A.1 and Table A.1 for further information). Within the low-mass Class 0 sample, the main-beam peak temperature, , ranges from 0.8 to 8.1 K. As indicated in Sect. 2.4, the emission in some sources (around 73% of the detected lines of this sub-group) can be decomposed into two velocity components. The FWHM of the narrower component varies from 2.3 km s-1 to 9.3 km s-1, while the width of the broad component shows a larger variation, from 8.3 km s-1 to 41.0 km s-1. For the low-mass Class I YSOs, similar intensity ranges are found, with varying from ~0.6 to 10.2 K. The Class I protostars present narrower emission lines than the Class 0 sources, and only the 27% of the emission line profiles can be decomposed into two velocity components. The narrow component ranges from 1.8 to 5.1 km s-1 and the broad component varies from 10.0 to 16.1 km s-1.

For the intermediate-mass protostars, the intensity increases and varies from .4 to ~28.0 K. The profiles are broader and the distinction between the two different components is clearer than for the low-mass sources, so all profiles can be fitted with two Gaussian functions. The FWHM of the two identified velocity components varies from 2.7 to 7.6 km s-1 for the narrow component and from 15.6 to 24.3 km s-1 for the broad component.

Only W3-IRS5 was observed in 12CO J = 10–9 from the high-mass sample. The spectrum is presented in Appendix B, Fig. B.3, together with other lines of this source. The profile is more intense than any of the low- and intermediate-mass sources (8.5 K) and has the largest FWHM: 8.4 km s-1 for the narrower component and 28.6 km s-1 for the broad component.

Self-absorption features have been detected in 5 out of 33 observed 12CO J = 10–9 emission lines (the sources are indicated in Table A.1). However, these features are weak and of the order of the rms of the spectrum, so no Gaussian profile has been fitted. No specific symmetry can be determined; that is, there is no systematic shift in the emission of the broad component relative to the source velocity (see Fig. A.1 for comparison). Overall, the data do not show any infall signature.

Appendix A.2: 13CO J = 10–9 line profiles

The observed 13CO J = 10–9 emission lines for the low- and intermediate-mass sources are less intense, narrower and have a lower S/N than the 12CO J = 10–9 spectra (Fig. A.2). Table A.2 contains the parameters obtained from the one or two Gaussian fits to the detected line profiles. In the case of the low-mass Class 0 spectra, three sources are not detected down to 17 mK rms in 0.27 km s-1 bins and the profile of only two sources (Ser SMM1 and NGC 1333 IRAS4A) can be decomposed into two different velocity components. The ranges from 0.05 to 0.8 K, and the FWHM of the narrow profiles varies from 0.7 to 6.8 km s-1, with the highest values corresponding to the broad velocity component being 13.2 km s-1 for NGC 1333 IRAS4A. In the case of the Class I sample, four sources are not detected and none of the emission line profiles can be decomposed into two velocity components. The averaged intensity is lower than for the Class 0 objects, ranging from .05 to 0.52 K. The value of the line width also drops, and the interval varies from 1.5 to 7.3 km s-1.

For the intermediate-mass YSOs, a better characterisation of the line profile is possible since the lines are stronger and have higher S/N than the low-mass objects with ranging from 0.1 to 2.7 K. Compared to the 12CO J = 10–9 profiles, the 13CO J = 10–9 lines are more symmetric and only the emission profile of one source can be decomposed into two different Gaussian components. For the FWHM of the lines fitted by the narrow Gaussian, the interval goes from 4.3 to 6.1 km s-1.

Around 63% of the detected 13CO J = 10–9 emission lines (12 out of 19) for the high-mass YSOs can be decomposed into two distinct velocity components, whereas the decomposition of the profiles is only possible for 10% of the detected low-mass objects (2 out of 20) and for ~17% of the detected intermediate-mass YSOs (1 out of 6). The reason for the lower percentage recorded for the low- and intermediate-mass sources could be the lower S/N than for the bright high-mass sources. The weakest line from the high-mass sample has a of 0.7 K and the most intense a of 20.8 K. The FWHM of the narrower component varies from 3.3 km s-1 to 7.2 km s-1. The width of the broad component presents a larger variation since the minimum value is 8.7 km s-1 and the maximum 21.9 km s-1. This component appears either red- or blue-shifted. There is no significant trend with evolution stage as probed by the presence of IR-brightness or ionising radiation (Fig. A.2).

Appendix A.3: C18O line profiles

Three transitions of C18O were obtained within WISH, together with water observations: C18O J = 5–4, J = 9–8 and J = 10–9. Only Class 0 and intermediate-mass YSOs were observed in C18O J = 5–4, tracing regions with an upper energy level of ~79 K (see Fig. A.3). This line is obtained in parallel with a deep integration on the 548 GHz HO 110 − 101 transition for 19 sources. Thus, the spectra have very high S/N with an rms of 9 mK for low-mass Class 0 sources and less than 20 mK for intermediate-mass YSOs in 0.27 km s-1 bins. The main characteristic of this transition is the narrow profile seen in all the emission lines for the narrower component, with a FWHM of less than 2.0 km s-1 for the low-mass sources, and 3.7 km s-1 for the intermediate-mass objects. In addition, other features are detected thanks to the high S/N, e.g. a weak broad velocity component for the low-mass objects NGC 1333 IRAS 4A (Yıldız et al. 2010), L483, Ser SMM1 and Ser SMM4. This component is also identified in the C18O J = 5–4 line for the intermediate-mass sources NGC 2071 (see Fig. 3) and Vela IRS19. The values of the single or two Gaussian fit of these lines are presented in Table A.3.

For the J = 9–8 transition, ~55% of the observed lines are detected, probably due to the lower S/N caused by shorter exposure times than for the J = 5–4 line. The lines are detected in 5 out of 26 low-mass sources; 4 out of 6 intermediate-mass YSOs; and in all 19 high-mass protostars (see Fig. A.4). The C18O J = 9–8 emission lines appear weak with median values of 0.10, 0.14 and 0.83 K for the low-, intermediate- and high-mass objects, respectively. Most of the emission line profiles of C18O J = 9–8 can be fitted by a single Gaussian with a FWHM from 2.0 km s-1 to 3.9 km s-1 for the low-mass objects; from 2.8 km s-1 to 5.4 km s-1 for the intermediate-mass sources; and from 3.1 to 6.4 km s-1 for the high-mass YSOs (values summarised in Table A.4). Only a two Gaussian decomposition has been performed for three ultra-compact HII regions (G10.47+0.03, W51N-e1 and G5.89-0.39). For these objects, the broad velocity components are more than 16 km s-1, as is shown in Fig. A.4.

Finally, the C18O J = 10–9 transition was observed in 30-min exposures for all low-mass Class 0 protostars, one intermediate-mass source and all high-mass YSOs. Additional deeper integrations of 300 min were obtained for NGC 1333 IRAS 2A (as part of WISH) and for NGC 1333 IRAS 4A, NGC 1333 IRAS 4B, Elias 29 and GSS 30 IRS1 (as part of open-time programme OT2_rvisser_2) in parallel with deep HO searches. The line was detected in five low-mass sources and in all 19 high-mass objects (Fig. A.5). This line appears close to the 1097 GHz H2O 312 − 303 transition. For most of the high-mass objects, the line profile of this water transition shows broad wings that extend a few km s-1, so the C18O J = 10 − 9 emission line is found on top of the broad water red wing. To properly analyse the emission of this CO isotopologue, the line wings of the 1097 GHz water transition were fitted with a Gaussian profile, subtracted and the residuals plotted. With this method, the C18O J = 10–9 emission line for the high-mass sample has been isolated. The temperature of the gas that J = 10–9 traces is likely similar to what is traced by the J = 9–8 transition, so the lines are also weak with median values of of 0.04 K for the low-mass protostars and 0.52 K for the high-mass objects. The FWHM of the one single Gaussian profile which fits these lines are slightly larger, ranging from 3.4 to 7.5 km s-1 for the high-mass sources (Table A.5 for more details).

thumbnail Fig. A.2

Same as Fig. A.1 but for the 13CO J = 10–9 spectra from the observed low-, intermediate- and high-mass YSOs. In the figure with the high-mass sample, the sources are presented according to their evolutionary stage. In the first row we find the mid-IR-quiet high-mass protostellar objects (HMPOs), in the second row the mid-IR-bright HMPOs, in the third line hot molecular cores and in the last row the ultra-compact Hii regions.

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Table A.2

Observed and fitted properties of the 13CO J = 10–9 line profiles for the detected sources.

thumbnail Fig. A.3

Same as Fig. A.1 but for the C18O J = 5–4 spectra of the low-mass (Class 0) and intermediate-mass protostars. For the low-mass sample the HRS spectra are presented, while the WBS data is used for the intermediate-mass objects.

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Table A.3

Observed and fitted properties of the C18O J = 5–4 line profiles for the observed sources.

thumbnail Fig. A.4

Same as Fig. A.1 but for the C18O J = 9–8 spectra from the low-, intermediate- and high-mass YSOs. The high-mass objects are organised according to their evolutionary stage, as is explained in Fig. A.2.

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Table A.4

Observed and fitted properties of the C18O J = 9–8 narrow line profiles for the detected sources.

thumbnail Fig. A.5

Same as Fig. A.1 but for the C18O J = 10–9 spectra of the observed low- and high-mass YSOs. In the case of the high-mass sources, the YSOs are organised as in Fig. A.2. The line wings of the 312 − 303 water transition for the high-mass sources have been fitted with a Gaussian profile, subtracted, and the residuals plotted to isolate the C18O J = 10–9 emission line.

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Table A.5

Observed and fitted properties of the C18O J = 10–9 line profiles for the detected sources.

Appendix B: JCMT data

The central spectrum of the 12CO and C18O J = 3–2 spectral maps observed with the HARP instrument of the JCMT are presented in this section (see Figs. B.4 and B.5). These central spectra were convolved to a 20″ beam in order to compare them with the HIFI data. The 12CO and C18O J = 3–2 spectra for the low-mass sources BHR 71, Ced110 IRS4, IRAS 12496 and HH 46 were observed with APEX because of their low declination. As for the JCMT data, the central spectrum was convolved to a 20″ beam. See Yıldız et al. (2013) for more information about the low-mass protostar observations.

The spectral maps are not presented in this paper because only the values of FWHM from the broad component for the 12CO J = 3–2 central spectrum were used in the analysis and discussion, together with the width and integrated intensity of the C18O J = 3–2 data. These values are presented in Table B.1. Some spectra from these species are also plotted with the HIFI data in the figures shown in this appendix in order to make a direct comparison of the lines for different types of protostars.

The 12CO J = 3–2 data show more complex line profiles than the J = 10–9, as indicated in Sect. 3.1, with intense self-absorption features and broad velocity components (see spectra from Fig. B.4). More than 82% of the observed and detected lines (39 out of 47) present a broad velocity component, and the FWHM ranges from 7.4 to 53.3 km s-1, values corresponding to low- and high-mass YSOs respectively.

On the other hand, the narrow C18O J = 3–2 spectra show single Gaussian emission profiles, similar to those from higher-J transitions observed with HIFI. The FWHM of these data varies from 0.6 to 7.3 km s-1. The spectra is presented in Fig. B.5 and the constrained values of FWHM and integrated intensity in Table B.1.

thumbnail Fig. B.1

Comparison between high-J HIFI and low-J JCMT spectra for the low-mass source Ser SMM1. 12CO J = 10–9 spectra (left-top) and C18O J = 9–8 line (right-top) observed with HIFI and for the 12CO J = 3–2 and C18O J = 3–2 lines (left-bottom and right-bottom respectively) observed with JCMT. The spectra have been resampled to 0.27 km s-1 and shifted to zero velocity. The green line indicates the baseline subtraction.

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thumbnail Fig. B.2

Same as Fig. B.1 but for the intermediate-mass source NGC 2071.

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thumbnail Fig. B.3

Same as Fig. B.1 but for the high-mass source W3-IRS5. The pink Gaussian profile represents the broad velocity component identified in the 12CO J = 10–9 line.

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Table B.1

Values of the FWHM for the 12CO J = 3–2 broad velocity component and the FWHM and integrated intensity for the C18O J = 3–2 spectra.

thumbnail Fig. B.4

12CO J = 3–2 spectra for low-, intermediate and high-mass YSOs. observed with the JCMT. The green line represents the baseline level and the pink Gaussian profile the broad velocity component for those sources for which a two Gaussian decomposition has been performed. All the spectra have been shifted to zero velocity. The numbers indicate where the spectra have been scaled for greater visibility.

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thumbnail Fig. B.5

Same as Fig. B.4 but for the C18O J = 3–2 spectra from the low-, intermediate- and high-mass YSOs.

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© ESO, 2013

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