ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O B-Wavelength I-Wavelength O O B-Wavelength I-Wavelength O O O O O O B-Survey O B-Survey O O O O B-Wavelength O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
tokens: showing the distribution of distance values are shown in Fig. 12 . Figure 12. Distance distribution based on methods 1 and 2 described in Section 4.4 . We further analysed the differences in physical parameters computed using distances from methods 1 and 2. The left-hand panel of Fig. 13 shows a comparison of the mass distributions from method 1 (green hatched histogram) and method 2 (solid red histogram). As expected from the differences in the distance distribution, the mass distributions from the two methods are slightly different. However, the overall statistics are similar – while method 1 gives a mean and median mass of 1570 and 930 M ⊙ , the respective values obtained by distances from method 2 are 1785 and 925 M ⊙ . A t -test between the two mass distributions gives a t -value of 0.71 with a significance value of 0.48. Thus, there is no significant difference in the distribution of masses computed using distances from the two methods. Figure 13. Mass distribution using two methods (left-hand panel) and (b) MR plot obtained using the distances obtained with the approach presented by Reid et al. ( 2016 ) (right-hand panel).The dashed green line represents the power-law fit to the data. The upper and lower solid red line shows the surface densities of 1 and 0.05 g cm −2 , respectively. The right-hand panel of Fig. 13 shows the mass-radius relation computed using distances from method 2. With method 2, 287 out of 320 sources satisfy the Kauffmann criterion for potential to form massive stars. This is comparable to method 1 wherein 295 out of 320 sources satisfy the Kauffmann criterion. Thus, although the distances from method 1 are different from that of method 2, the overall statistical properties of sources associated with 6.7 GHz methanol masers are similar between the two methods. We are thus unable to make any distinction regarding accuracy of distances when considering the entire sample statistically. 5 CONCLUSION We have constructed SEDs from 870 to 70 μm for 320 6.7 GHz methanol masers using data from the ATLASGAL and Hi-GAL surveys. The SEDs from 870 to 160 μm were fitted with single-component grey body models. We observe a mean dust temperature of 22 K confirming the later evolutionary stage of the maser sources in comparison to infrared dark clouds, with some sources showing temperatures as high as 48 K. Almost 92 per cent of the methanol maser sources satisfy the Kauffmann criterion for potential to form massive stars. A comparison of the mass–luminosity diagram of the sample with simple evolutionary tracks from the turbulent core model suggest that most methanol masers are associated with massive young stellar objects with over 90 per cent in early evolutionary stages of accelerating accretion. However, there also appears to be a small population of sources that are likely to be associated with intermediate- or low-mass stars suggesting that the association between high-mass star formation and methanol maser emission is not