ABSTRACT We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only ...12.162 ± 0.005 pc away from the Solar system with one of the lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors 42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory, as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of 12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
ABSTRACT
We present the confirmation of a hot super-Neptune with an exterior Neptune companion orbiting a bright (V = 10.1 mag) F-dwarf identified by the Transiting Exoplanet Survey Satellite ...(TESS). The two planets, observed in sectors 45, 46, and 48 of the TESS extended mission, are $4.74_{-0.14}^{+0.16}$ and $3.86_{-0.16}^{+0.17}$ R⊕ with $5.4588385_{-0.0000072}^{+0.0000070}$ and $17.8999_{-0.0013}^{+0.0018}$ d orbital periods, respectively. We also obtained precise space-based photometric follow-up of the system with ESA’s CHaracterising ExOplanets Satellite to constrain the radius and ephemeris of TOI-5126 b. TOI-5126 b is located in the ‘hot Neptune Desert’ and is an ideal candidate for follow-up transmission spectroscopy due to its high-predicted equilibrium temperature (Teq = ${1442}_{-40}^{+46}$ K) implying a cloud-free atmosphere. TOI-5126 c is a warm Neptune (Teq = $971_{-27}^{+31}$ K) also suitable for follow-up. Tentative transit timing variations have also been identified in analysis, suggesting the presence of at least one additional planet, however this signal may be caused by spot-crossing events, necessitating further precise photometric follow-up to confirm these signals.
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a bright (\(V=12.6\) mag, \(K=7.8\) mag) metal-poor M4V star only ...\(12.162\pm0.005\) pc away from the Solar System with one of the lowest stellar activity levels known for an M-dwarf. A planet candidate was detected by TESS based on only 3 transits in sectors 42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory, as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of \(12.76144\pm0.00006\) days and a radius of \(1.0\pm{0.1}\) R\(_\oplus\), resulting in an equilibrium temperature of \(\sim\)315K. Gliese 12 b has excellent future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the Galaxy.
We report the discovery of two mini-Neptunes in near 2:1 resonance orbits (\(P=7.610303\) d for HIP 113103 b and \(P=14.245651\) d for HIP 113103 c) around the adolescent K-star HIP 113103 (TIC ...121490076). The planet system was first identified from the TESS mission, and was confirmed via additional photometric and spectroscopic observations, including a \(\sim\)17.5 hour observation for the transits of both planets using ESA CHEOPS. We place \(\leq4.5\) min and \(\leq2.5\) min limits on the absence of transit timing variations over the three year photometric baseline, allowing further constraints on the orbital eccentricities of the system beyond that available from the photometric transit duration alone. With a planetary radius of \(R_{p}=1.829^{+0.096}_{-0.067}\,R_{\oplus}\), HIP 113103 b resides within the radius gap, and this might provide invaluable information on the formation disparities between super-Earths and mini-Neptunes. Given the larger radius \(R_{p}=2.40^{+0.10}_{-0.08}\,R_{\oplus}\) for HIP 113103 c, and close proximity of both planets to HIP 113103, it is likely that HIP 113103 b might have lost (or is still losing) its primordial atmosphere. We therefore present simulated atmospheric transmission spectra of both planets using JWST, HST, and Twinkle. It demonstrates a potential metallicity difference (due to differences in their evolution) would be a challenge to detect if the atmospheres are in chemical equilibrium. As one of the brightest multi sub-Neptune planet systems suitable for atmosphere follow up, HIP 113103 b and HIP 113103 c could provide insight on planetary evolution for the sub-Neptune K-star population.
The recent discoveries of Neptune-sized ultra-short period planets (USPs) challenge existing planet formation theories. It is unclear whether these residents of the Hot Neptune Desert have similar ...origins to smaller, rocky USPs, or if this discrete population is evidence of a different formation pathway altogether. We report the discovery of TOI-3261b, an ultra-hot Neptune with an orbital period \(P\) = 0.88 days. The host star is a \(V = 13.2\) magnitude, slightly super-solar metallicity (Fe/H \(\simeq\) 0.15), inactive K1.5 main sequence star at \(d = 300\) pc. Using data from the Transiting Exoplanet Survey Satellite and the Las Cumbres Observatory Global Telescope, we find that TOI-3261b has a radius of \(3.82_{-0.35}^{+0.42}\) \(R_{\oplus}\). Moreover, radial velocities from ESPRESSO and HARPS reveal a mass of \(30.3_{-2.4}^{+2.2}\) \(M_{\oplus}\), more than twice the median mass of Neptune-sized planets on longer orbits. We investigate multiple mechanisms of mass loss that can reproduce the current-day properties of TOI-3261b, simulating the evolution of the planet via tidal stripping and photoevaporation. Thermal evolution models suggest that TOI-3261b should retain an envelope potentially enriched with volatiles constituting \(\sim\)5% of its total mass. This is the second highest envelope mass fraction among ultra-hot Neptunes discovered to date, making TOI-3261b an ideal candidate for atmospheric follow-up observations.
We present the confirmation of a hot super-Neptune with an exterior Neptune
companion orbiting a bright (V = 10.1 mag) F-dwarf identified by the
$\textit{Transiting Exoplanet Survey Satellite}$ ...($\textit{TESS}$). The two
planets, observed in sectors 45, 46 and 48 of the $\textit{TESS}$ extended
mission, are $4.74^{+0.16}_{-0.14}$ $R_{\oplus}$ and $3.86^{+0.17}_{-0.16}$
$R_{\oplus}$ with $5.4588385^{+0.0000070}_{-0.0000072}$ d and
$17.8999^{+0.0018}_{-0.0013}$ d orbital periods, respectively. We also obtained
precise space based photometric follow-up of the system with ESAs
$\textit{CHaracterising ExOplanets Satellite}$ ($\textit{CHEOPS}$) to constrain
the radius and ephemeris of TOI-5126 b. TOI 5126 b is located in the "hot
Neptune Desert" and is an ideal candidate for follow-up transmission
spectroscopy due to its high predicted equilibrium temperature ($T_{eq} =
1442^{+46}_{-40}$ K) implying a cloud-free atmosphere. TOI-5126 c is a warm
Neptune ($T_{eq}= 971^{+31}_{-27}$ K) also suitable for follow-up. Tentative
transit timing variations (TTVs) have also been identified in analysis,
suggesting the presence of at least one additional planet, however this signal
may be caused by spot-crossing events, necessitating further precise
photometric follow-up to confirm these signals.
We present the confirmation of a hot super-Neptune with an exterior Neptune companion orbiting a bright (V = 10.1 mag) F-dwarf identified by the \(\textit{Transiting Exoplanet Survey Satellite}\) ...(\(\textit{TESS}\)). The two planets, observed in sectors 45, 46 and 48 of the \(\textit{TESS}\) extended mission, are \(4.74^{+0.16}_{-0.14}\) \(R_{\oplus}\) and \(3.86^{+0.17}_{-0.16}\) \(R_{\oplus}\) with \(5.4588385^{+0.0000070}_{-0.0000072}\) d and \(17.8999^{+0.0018}_{-0.0013}\) d orbital periods, respectively. We also obtained precise space based photometric follow-up of the system with ESAs \(\textit{CHaracterising ExOplanets Satellite}\) (\(\textit{CHEOPS}\)) to constrain the radius and ephemeris of TOI-5126 b. TOI 5126 b is located in the "hot Neptune Desert" and is an ideal candidate for follow-up transmission spectroscopy due to its high predicted equilibrium temperature (\(T_{eq} = 1442^{+46}_{-40}\) K) implying a cloud-free atmosphere. TOI-5126 c is a warm Neptune (\(T_{eq}= 971^{+31}_{-27}\) K) also suitable for follow-up. Tentative transit timing variations (TTVs) have also been identified in analysis, suggesting the presence of at least one additional planet, however this signal may be caused by spot-crossing events, necessitating further precise photometric follow-up to confirm these signals.
