As is sometimes the way when prime observations are open access, two independent papers (Daylan et al 2019; Bourrier et al 2019) have, on the same day, announced independent analyses of the TESS lightcurve of the ultra-hot Jupiter WASP-121b.

The phase curve shows the transit (time zero), a “phase curve” modulation caused by the varying visibility of the heated face of the planet (illustrated by schematics of the planet), and the eclipse (when the planet passes behind the star, at −15 hr).

Both analyses report similar findings, saying that the heated “hot spot” directly faces the star, rather than being offset in phase, which suggests that any re-circulation of heat by planetary winds is inefficient.

The planet’s atmosphere shows a temperature inversion (it is hotter at higher altitudes), which could result from absorption of heat by molecules of titanium and vanadium oxide, and H-minus ions.