Context. Planetary population analysis gives us insight into formation
and evolution processes. For short-period planets, the sub-Jovian desert
has been discussed in recent years with regard to the planet population
in the mass/period and radius/period parameter space without taking
stellar parameters into account. The Next Generation Transit Survey
(NGTS) is optimised for detecting planets in this regime, which allows
for further analysis of the sub-Jovian desert. Aims: With
high-precision photometric surveys (e.g. with NGTS and TESS), which aim
to detect short period planets especially around M/K-type host stars,
stellar parameters need to be accounted for when empirical data are
compared to model predictions. Presenting a newly discovered planet at
the boundary of the sub-Jovian desert, we analyse its bulk properties
and use it to show the properties of exoplanets that border the
sub-Jovian desert. Methods: Using NGTS light curve and
spectroscopic follow-up observations, we confirm the planetary nature of
planet NGTS-5b and determine its mass. Using exoplanet archives, we set
the planet in context with other discoveries. Results: NGTS-5b is
a short-period planet with an orbital period of 3.3569866 ±
0.0000026 days. With a mass of 0.229 ± 0.037 MJup and
a radius of 1.136 ± 0.023 RJup, it is highly inflated.
Its mass places it at the upper boundary of the sub-Jovian desert.
Because the host is a K2 dwarf, we need to account for the stellar
parameters when NGTS-5b is analysed with regard to planet populations.
Conclusions: With red-sensitive surveys (e.g. with NGTS and
TESS), we expect many more planets around late-type stars to be
detected. An empirical analysis of the sub-Jovian desert should
therefore take stellar parameters into account.
Based on observations made with CORALIE echelle spectrograph mounted on
the 1.2 m Swiss telescope and the HARPS spectrograph on the ESO 3.6 m
telescope, both at La Silla observatory (ESO, Chile). HARPS programme
IDs are 098.C-0820(A), 099.C-0303(A), 0100.C-0474(A), and
- planets and satellites: detection
- planets and satellites: gaseous planets