Carbon dioxide (CO2) is a key chemical species that is found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the metal enrichment (that is, elements heavier than helium, also called ‘metallicity’)1–3 , and thus the formation processes of the primary atmospheres of hot gas giants4–6 . It is also one of

Context. Ultra-short-period (USP) planets are defined as planets with orbital periods shorter than one day. This type of planets is rare, highly irradiated, and interesting because their formation history is unknown. Aims: We aim to obtain precise mass and radius measurements to confirm the planetary nature of a USP candidate found by the

Context. The HD 108236 system was first announced with the detection of four small planets based on TESS data. Shortly after, the transit of an additional planet with a period of 29.54 d was serendipitously detected by CHEOPS. In this way, HD 108236 (V = 9.2) became one of the brightest stars known to host five small transiting planets (Rp < 3 R⊕)

Recent studies based on photometry from the Transiting Exoplanet Survey Satellite (TESS) have suggested that the dayside of KELT-1b, a strongly irradiated brown dwarf, is significantly brighter in visible light than what would be expected based on Spitzer observations in the infrared. We observed eight eclipses of KELT-1b with CHaracterising

Aims: Stellar flares emit thermal and nonthermal radiation in the X-ray and ultraviolet (UV) regime. Although high energetic radiation from flares is a potential threat to exoplanet atmospheres and may lead to surface sterilization, it might also provide the extra energy for low-mass stars needed to trigger and sustain prebiotic chemistry. Despite

Ultra-hot Jupiters are highly irradiated gas giant exoplanets on close-in orbits around their host stars. The dayside atmospheres of these objects strongly emit thermal radiation due to their elevated temperatures, making them prime targets for characterization by emission spectroscopy. We analyzed high-resolution spectra from CARMENES, HARPS-N

Much remains to be understood about the nature of exoplanets smaller than Neptune, most of which have been discovered in compact multi-planet systems. With its inner ultra-short period planet b aligned with the star and two larger outer planets d-c on polar orbits, the multi-planet system HD 3167 features a peculiar architecture and offers the

Context. Observations of the phase curves and secondary eclipses of extrasolar planets provide a window onto the composition and thermal structure of the planetary atmospheres. For example, the photometric observations of secondary eclipses lead to the measurement of the planetary geometric albedo, Ag, which is an indicator of the presence of

Exoplanets smaller than Neptune are common around red dwarf stars (M dwarfs), with those that transit their host star constituting the bulk of known temperate worlds amenable for atmospheric characterization. We analyze the masses and radii of all known small transiting planets around M dwarfs, identifying three populations: rocky, water-rich, and

The Transiting Exoplanet Survey Satellite mission identified a deep and asymmetric transit-like signal with a periodicity of 4.5 days orbiting the M4 dwarf star TOI-3884. The signal has been confirmed by follow-up observations collected by the ExTrA facility and Las Cumbres Observatory Global Telescope, which reveal that the transit is chromatic

Aims: With the aim of finding microlensing binaries containing brown dwarf (BD) companions, we investigate the microlensing survey data collected during the 2016-2018 seasons. Methods: For this purpose, we first modeled lensing events with light curves exhibiting anomaly features that are likely to be produced by binary lenses. We then sorted out

Context. In the age of JWST, temperate terrestrial exoplanets transiting nearby late-type M dwarfs provide unique opportunities for characterising their atmospheres, as well as searching for biosignature gases. In this context, the benchmark TRAPPIST-1 planetary system has garnered the interest of a broad scientific community. Aims: We report here

Observations of helium in exoplanet atmospheres may reveal the presence of large gaseous envelopes and indicate ongoing atmospheric escape. Orell-Miquel et al. (2022) used CARMENES to measure a tentative detection of helium for the sub-Neptune GJ 1214b, with a peak excess absorption reaching over 2% in-transit depth at 10830 Å. However, several non

Context. Statistical analyses based on Kepler data show that most of the early-type M dwarfs host multi-planet systems consisting of Earth- to sub-Neptune-sized planets with orbital periods of up to ~250 days, and that at least one such planet is likely located within the habitable zone. M dwarfs are therefore primary targets to search for

The hot Neptune desert is a region hosting a small number of short-period Neptunes in the radius-instellation diagram. Highly irradiated planets are usually either small (R ≲ 2 R⊕) and rocky or they are gas giants with radii of ≳1 RJ. Here, we report on the intermediate-sized planet TOI-2196 b (TIC 372172128.01) on a 1.2 day orbit around a G-type

Context. Despite being a prominent subset of the exoplanet population discovered in the past three decades, the nature and provenance of sub-Neptune-sized planets is still one of the open questions in exoplanet science. Aims: For planets orbiting bright stars, precisely measuring the orbital and planet parameters of the system is the best approach

We report the discovery and characterization of two small transiting planets orbiting the bright M3.0V star TOI-1468 (LSPM J0106+1913), whose transit signals were detected in the photometric time series in three sectors of the TESS mission. We confirm the planetary nature of both of them using precise radial velocity measurements from the CARMENES

We report the confirmation and characterisation of TOI-1820 b, TOI-2025 b, and TOI-2158 b, three Jupiter-sized planets on short-period orbits around G-type stars detected by TESS. Through our ground-based efforts using the FIES and Tull spectrographs, we have confirmed these planets and characterised their orbits, and find periods of around 4.9 d

We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (M* = 1.109 ± 0.043M⊙, R* = 1.043 ± 0.009 R⊙) in a visual binary system. We combined TESS and CHEOPS space-borne photometry with MuSCAT 2 ground-based photometry, `Alopeke and PHARO high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and SOPHIE

We explore how finite integration time or temporal binning can affect the analysis of exoplanet phase curves. We provide analytical formulae to account for this effect or, if neglected, to estimate the potential biases in the retrieved parameters. As expected, due to their smoother variations over longer time-scales, phase curves can be binned more