1 research outputs found
Homogeneous search for helium in the atmosphere of 11 gas giant exoplanets with SPIRou
The metastable helium triplet in the near-infrared (10833{\AA}) is among the
most important probes of exoplanet atmospheres. It can trace their extended
outer layers and constrain mass-loss. We use the near-infrared high-resolution
spectropolarimeter SPIRou on the CFHT to search for the spectrally resolved
helium triplet in the atmospheres of eleven exoplanets, ranging from warm
mini-Neptunes to hot Jupiters and orbiting G, K, and M dwarfs. Observations
were obtained as part of the SPIRou Legacy Survey and complementary open-time
programs. We apply a homogeneous data reduction to all datasets and set
constraints on the presence of metastable helium, despite the presence of
systematics in the data. We confirm published detections for HAT-P-11b,
HD189733b, and WASP-69b and set upper limits for the other planets. We apply
the p-winds open source code to set upper limits on the mass-loss rate for the
non-detections and to constrain the thermosphere temperature, mass-loss rate,
line-of-sight velocity, and the altitude of the thermosphere for the
detections. We confirm that the presence of metastable helium correlates with
the stellar mass and the XUV flux received by the planets. We investigated the
correlation between the mass-loss rate and the presence of metastable helium,
but it remains difficult to draw definitive conclusions. Finally, some of our
results are in contradiction with previous results in the literature, therefore
we stress the importance of repeatable, homogeneous, and larger-scale analyses
of the helium triplet to obtain robust statistics, study temporal variability,
and better understand how the helium triplet can be used to explore the
evolution of exoplanets.Comment: 28 pages, 13 figures, Accepted in A&A for publicatio