ner_tags: O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O 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 B-CelestialObject O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength O O O O O O O B-Wavelength I-Wavelength I-Wavelength B-Telescope B-Instrument O O O O O O O B-Wavelength O B-Wavelength I-Wavelength I-Wavelength O O O O O O O O B-Wavelength I-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 B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O B-CelestialObject O O O O O O B-Software O O O O O O O O O O O O B-Formula I-Formula I-Formula 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-CelestialObject O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation O O O O O O B-Citation I-Citation I-Citation I-Citation O O O B-Citation I-Citation I-Citation I-Citation O O B-Citation I-Citation I-Citation I-Citation O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O B-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O B-CelestialObjectRegion I-CelestialObjectRegion I-CelestialObjectRegion O O O O O O O O O O O B-Software O O O O O O O O O O O O O O O O O O O O O O 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 I-Wavelength 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 B-CelestialObject O O O O O O O O O O B-CelestialObjectRegion O B-Citation I-Citation I-Citation I-Citation O B-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 B-CelestialObjectRegion I-CelestialObjectRegion I-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 O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O
tokens: to calculate both the planetary and stellar spectra from 10 to 10 6 Å. The planetary, stellar, and orbital parameters used for the computation irradiated model of WASP-19b are summarised in Table 1 . 3 Results and discussion A thermal spectrum of WASP-19b from Anderson et al. (2010) , Anderson et al. (2013) , Gibson et al. (2010) , Burton et al. (2012) , Bean et al. (2013) , and Lendl et al. (2013) , is shown in Fig 1 . The planet-to-star flux ratio at 4.5 μ m is higher than the one at the 3.6 μ m Spitzer /IRAC channel. Moreover, at higher wavelengths, namely at 5.8 and 8.0 μ m, the planet-to-star flux ratio is even higher than 4.5 μ m. This clearly indicates the presence of excess emission in some photometric bands over others. Table 1 Planetary, stellar, and orbital parameters used in the model are from Butler et al. (2006) , Southworth et al. (2007) , Hebb et al. (2010) , and Hellier et al. (2011) . Fig. 1 Comparison of observed thermal spectra of WASP-19b with the modelled spectra calculated using PHOENIX (solid line) at different metallicities with an average dayside heat redistribution ( f = 0.5). The corresponding temperature-pressure profile is shown in the inset image (the grey shaded region corresponds to the structure inversion). The observed thermal spectrum of WASP-19b presented in this paper is adopted from Anderson et al. (2010 , 2013 ) (filled square and filled circles), Gibson et al. (2010) (filled upward triangle), Bean et al. (2013) (open circles), Burton et al. (2012) (open diamond), and Lendl et al. (2013) (filled downward triangles). The emission features at 4.5 μ m are due to CO in the presence of thermal inversion. The atmosphere of WASP-19b has been modelled with the parameters given in Table 1 using PHOENIX . It shows the presence of thermal inversion (see inset diagram, Fig. 1 ) and the equilibrium temperature is found to be ~ 2700 K. The comparison between observational data and our theoretical modelling (see Fig. 1 ) indicates that the excess planet-to-star flux ratio at 4.5 μ m is due to the presence of CO, which in turn is caused by thermal inversion that exists in the atmosphere. The corresponding pressure range, as probed by the secondary eclipse, is 10 −2 to 10 −3 bar. Previous studies of WASP-19b did not show any evidence of thermal inversion in its atmosphere ( Anderson et al. 2013 ; Bean et al. 2013 ). However, these studies were mainly based on retrieval techniques where abundances and thermal structure were fitted to the data. We investigate the effect of metallicity on the atmosphere of WASP-19b by changing all the heavy-elemental abundances by a factor of two. As shown by the inset image of Fig. 1 , the thermal inversion becomes stronger as the metallicity increases. This is mainly due to the temperature dependence of the thermal dissociation of various molecules, which changes the photospheric abundances ratio of TiO and H 2 O at different metallicities ( Parmentier et al. 2018 ). At higher