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 B-CelestialObjectRegion O O O O O O O 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-CelestialObjectRegion O O O B-CelestialObject O B-CelestialRegion I-CelestialRegion I-CelestialRegion O O O O O O B-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 B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O B-CelestialRegion I-CelestialRegion I-CelestialRegion O O O O O O O O O O O B-CelestialObject O O O O O O O O O O B-CelestialObject 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-CelestialObjectRegion O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O B-CelestialObjectRegion O O O O O O O O O B-CelestialObject O O O O O O O O O O O O O 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-CelestialObjectRegion O O O O O O O O O B-CelestialObject O O O O O O O O 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-CelestialObjectRegion O O O O O O O O O O O O B-CelestialObjectRegion O B-CelestialObject O O O O B-Wavelength B-Wavelength O O O O B-CelestialObjectRegion O B-CelestialObject O O O O O 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 B-CelestialObjectRegion O O O O O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O 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 B-CelestialObjectRegion O O O O O O O O B-CelestialObject O O O O O O O O O O O B-Model O O O O O O O O O O O O O O O B-CelestialObject O B-CelestialObjectRegion O O O O O O O O O O O O O O O O O O O O O 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-CelestialObjectRegion O B-Tag O O O O O O O O O O O O O O B-Formula I-Formula I-Formula O O
tokens: velocity distribution of the gas within the velocity range from 495 to 495kms 1 (1kms 1 steps). The emission for one square degree centred on the SMCNOD exhibits two main peaks: 94 and 186kms 1 (which are shown in Figs 8 and 9 , respectively). These velocities agree with the velocity field related to the MS at the SMCNOD position, at an MS longitude L MS 25. See for example fig. 8 in Nidever etal. ( 2010 ). We discuss details about H i gas distribution in Section 4 . Figure 7. H i gas column density map from Kalberla Haud ( 2015 ), in zenith equal area projection, close to the south celestial pole. A grid of equatorial coordinates ( and ) is indicated. The SMC is close to the centre of the figure and the LMC is located near the bright spot in the lower-left corner. No significant excess of H i gas is observed at the position of the SMCNOD (dotted ellipse). Figure 8. H i gas emission map from Kalberla Haud ( 2015 ), in equatorial coordinates for the velocity channel 94kms 1 v LSR 95kms 1 . The SMCNOD position is highlighted by an empty ellipse and the SMC centre by a plus symbol. Figure 9. Same as Fig. 8 but for velocity channel equal to 186kms 1 (186kms 1 v LSR 187kms 1 ). 4 DISCUSSION In this section, we discuss the characteristics of the SMCNOD: we compare its stellar populations to those of the SMC (Section 4.1 ), its gas content (Section 4.2 ), possible scenarios for its origin (Section 4.3 ) and in the last subsection we provide a brief summary of the discovery, discussing the SMCNOD fate and some prospects for future analyses (Section 4.4 ). 4.1 The SMCNOD and SMC stellar populations The ( g r ) colour distributions of SMCNOD and SMC stars for 3 mag ranges in the Hess diagram from Fig. 2 are shown in the left-hand panel of Fig. 10 , whereas their number counts in bins of g magnitude filtered by the CMD mask and normalized (to the areas) are presented in the right-hand panel of the same figure. The colour distributions look very similar. For RC stars (solid lines), there may be a slight preference for the SMCNOD being a little bluer than the SMC. However, a KolmogorovSmirnov (KS) test indicates that the two RC populations come from the same parent distribution ( p 0.42). As for the LF comparison, the two distributions look similar as well. Figure 10. Histograms in bins of colour (left) and in bins of g magnitude (right) filtered by the CMD mask for the SMCNOD (third panel in Fig. 2 ) and the SMC (fifth panel in Fig. 2 ). In the right-hand panel, the Poissonian uncertainties are shown as shaded areas. The stellar colour distribution is very similar between the SMC and SMCNOD in the left-hand panel (comparing dotted red and blue lines and dashed red and blue lines), as well as the histogram in bins of magnitude for the stars filtered with the CMD mask in the last two panels in Fig. 2 (right-hand panel). 4.2 The SMCNOD and H<sc>i</sc> gas The results of considering the H i gas velocity channels are inconclusive. The v LSR =186kms 1 channel