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 the discovery and validation of two temperate super-Earths transiting LP 890-9 (TOI-4306, SPECULOOS-2), a relatively low-activity nearby (32 pc) M6V star. The inner planet, LP 890-9 b, was first detected by TESS (and identified as TOI-4306.01) based on four sectors of data. Intensive photometric monitoring of the system with the SPECULOOS Southern Observatory then led to the discovery of a second outer transiting planet, LP 890-9 c (also identified as SPECULOOS-2 c), previously undetected by TESS. The orbital period of this second planet was later confirmed by MuSCAT3 follow-up observations.
Methods.
We first inferred the properties of the host star by analyzing its Lick/Kast optical and IRTF/SpeX near-infrared spectra, as well as its broadband spectral energy distribution, and
Gaia
parallax. We then derived the properties of the two planets by modelling multi-colour transit photometry from TESS, SPECULOOS-South, MuSCAT3, ExTrA, TRAPPIST-South, and SAINT-EX. Archival imaging, Gemini-South/Zorro high-resolution imaging, and Subaru/IRD radial velocities also support our planetary interpretation.
Results.
With a mass of 0.118 ± 0.002
M
⊙
, a radius of 0.1556 ± 0.0086
R
⊙
, and an effective temperature of 2850 ± 75 K, LP 890-9 is the second-coolest star found to host planets, after TRAPPIST-1. The inner planet has an orbital period of 2.73 d, a radius of 1.320
−0.027
+0.053
R
⊕
, and receives an incident stellar flux of 4.09 ± 0.12
S
⊕
. The outer planet has a similar size of 1.367
−0.039
+0.055
R
⊕
and an orbital period of 8.46 d. With an incident stellar flux of 0.906 ± 0.026
S
⊕
, it is located within the conservative habitable zone, very close to its inner limit (runaway greenhouse). Although the masses of the two planets remain to be measured, we estimated their potential for atmospheric characterisation via transmission spectroscopy using a mass-radius relationship and found that, after the TRAPPIST-1 planets, LP 890-9 c is the second-most favourable habitable-zone terrestrial planet known so far (assuming for this comparison a similar atmosphere for all planets).
Conclusions.
The discovery of this remarkable system offers another rare opportunity to study temperate terrestrial planets around our smallest and coolest neighbours.
We report the discovery of GJ 3929 b, a hot Earth-sized planet orbiting the nearby M3.5 V dwarf star, GJ 3929 (G 180-18, TOI-2013). Joint modelling of photometric observations from TESS sectors 24 ...and 25 together with 73 spectroscopic observations from CARMENES and follow-up transit observations from SAINT-EX, LCOGT, and OSN yields a planet radius of
R
b
= 1.150 ± 0.040
R
⊕
, a mass of
M
b
= 1.21 ± 0.42
M
⊕
, and an orbital period of
P
b
= 2.6162745 ± 0.0000030
d
. The resulting density of
ρ
b
= 4.4 ± 1.6 g cm
−3
is compatible with the Earth’s mean density of about 5.5 g cm
−3
. Due to the apparent brightness of the host star (
J
= 8.7 mag) and its small size, GJ 3929 b is a promising target for atmospheric characterisation with the JWST. Additionally, the radial velocity data show evidence for another planet candidate with
P
c
= 14.303 ± 0.035 d, which is likely unrelated to the stellar rotation period,
P
rot
= 122 ± 13 d, which we determined from archival HATNet and ASAS-SN photometry combined with newly obtained TJO data.
Several planetary formation models have been proposed to explain the observed abundance and variety of compositions of super-Earths and mini-Neptunes. In this context, multitransiting systems ...orbiting low-mass stars whose planets are close to the radius valley are benchmark systems, which help to elucidate which formation model dominates. We report the discovery, validation, and initial characterization of one such system, TOI-2096, composed of a super-Earth and a mini-Neptune hosted by a mid-type M dwarf located 48 pc away. We first characterized the host star by combining different methods. Then, we derived the planetary properties by modeling the photometric data from TESS and ground-based facilities. We used archival data, high-resolution imaging, and statistical validation to support our planetary interpretation. We found that TOI-2096 corresponds to a dwarf star of spectral type M4. It harbors a super-Earth (R\(\sim1.2 R_{\oplus}\)) and a mini-Neptune (R\(\sim1.90 R_{\oplus}\)) in likely slightly eccentric orbits with orbital periods of 3.12 d and 6.39 d, respectively. These orbital periods are close to the first-order 2:1 mean-motion resonance (MMR), which may lead to measurable transit timing variations (TTVs). We computed the expected TTVs amplitude for each planet and found that they might be measurable with high-precision photometry delivering mid-transit times with accuracies of \(\lesssim\)2 min. Moreover, measuring the planetary masses via radial velocities (RVs) is also possible. Lastly, we found that these planets are among the best in their class to conduct atmospheric studies using the James Webb Space Telescope (JWST). The properties of this system make it a suitable candidate for further studies, particularly for mass determination using RVs and/or TTVs, decreasing the scarcity of systems that can be used to test planetary formation models around low-mass stars.
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. We report here the discovery and validation of two temperate super-Earths transiting LP 890-9 (TOI-4306, SPECULOOS-2), a relatively low-activity nearby (32 pc) M6V star. The inner planet, LP 890-9b, was first detected by TESS (and identified as TOI-4306.01) based on four sectors of data. Intensive photometric monitoring of the system with the SPECULOOS Southern Observatory then led to the discovery of a second outer transiting planet, LP 890-9c (also identified as SPECULOOS-2c), previously undetected by TESS. The orbital period of this second planet was later confirmed by MuSCAT3 follow-up observations. With a mass of 0.118\(\pm\)0.002 \(M_\odot\), a radius of 0.1556\(\pm\)0.0086 \(R_\odot\), and an effective temperature of 2850\(\pm\)75 K, LP 890-9 is the second-coolest star found to host planets, after TRAPPIST-1. The inner planet has an orbital period of 2.73 d, a radius of \(1.320_{-0.027}^{+0.053}\) \(R_\oplus\), and receives an incident stellar flux of 4.09\(\pm\)0.12 \(S_\oplus\). The outer planet has a similar size of \(1.367_{-0.039}^{+0.055}\) \(R_\oplus\) and an orbital period of 8.46 d. With an incident stellar flux of 0.906 \(\pm\) 0.026 \(S_\oplus\), it is located within the conservative habitable zone, very close to its inner limit. Although the masses of the two planets remain to be measured, we estimated their potential for atmospheric characterisation via transmission spectroscopy using a mass-radius relationship and found that, after the TRAPPIST-1 planets, LP 890-9c is the second-most favourable habitable-zone terrestrial planet known so far. The discovery of this remarkable system offers another rare opportunity to study temperate terrestrial planets around our smallest and coolest neighbours.
We report the discovery of GJ 3929 b, a hot Earth-sized planet orbiting the nearby M3.5 V dwarf star, GJ 3929 (G 180--18, TOI-2013). Joint modelling of photometric observations from TESS sectors 24 ...and 25 together with 73 spectroscopic observations from CARMENES and follow-up transit observations from SAINT-EX, LCOGT, and OSN yields a planet radius of \(R_b = 1.150 +/- 0.040\) R\(_{earth}\), a mass of \(M_b = 1.21 +/- 0.42\) M\(_{earth}\), and an orbital period of \(P_b = 2.6162745 +/- 0.0000030\) d. The resulting density of \(\rho_b= 4.4 +/- 1.6\) g/cm\(^{-3}\) is compatible with the Earth's mean density of about 5.5 g/cm\(^{-3}\). Due to the apparent brightness of the host star (J=8.7 mag) and its small size, GJ 3929 b is a promising target for atmospheric characterisation with the JWST. Additionally, the radial velocity data show evidence for another planet candidate with \(P_{c} = 14.303 +/- 0.035\) d, which is likely unrelated to the stellar rotation period, \(P_{rot} = 122+/-13\) d, which we determined from archival HATNet and ASAS-SN photometry combined with newly obtained TJO data.
Thanks to the relative ease of finding and characterizing small planets around M dwarf stars, these objects have become cornerstones in the field of exoplanet studies. The current paucity of planets ...in long-period orbits around M dwarfs make such objects particularly compelling as they provide clues about the formation and evolution of these systems. In this study, we present the discovery of TOI-2257 b (TIC 198485881), a long-period (35 d) sub-Neptune orbiting an M3 star at 57.8pc. Its transit depth is about 0.4%, large enough to be detected with medium-size, ground-based telescopes. The long transit duration suggests the planet is in a highly eccentric orbit (\(e \sim 0.5\)), which would make it the most eccentric planet that is known to be transiting an M-dwarf star. We combined TESS and ground-based data obtained with the 1.0-m SAINT-EX, 0.60-m TRAPPIST-North and 1.2-m FLWO telescopes to find a planetary size of 2.2 \(R_{\oplus}\) and an orbital period of 35.19 days. In addition, we make use of archival data, high-resolution imaging, and vetting packages to support our planetary interpretation. With its long period and high eccentricity, TOI-2257 b falls in a novel slice of parameter space. Despite the planet's low equilibrium temperature (\(\sim\) 256 K), its host star's small size (\(R_* = 0.311 \pm{0.015}\)) and relative infrared brightness (K\(_{mag}\) = 10.7) make it a suitable candidate for atmospheric exploration via transmission spectroscopy.
Large sub-Neptunes are uncommon around the coolest stars in the Galaxy and are rarer still around those that are metal-poor. However, owing to the large planet-to-star radius ratio, these planets are ...highly suitable for atmospheric study via transmission spectroscopy in the infrared, such as with JWST. Here we report the discovery and validation of a sub-Neptune orbiting the thick-disk, mid-M dwarf star TOI-2406. We first infer properties of the host star by analysing the star's near-infrared spectrum, spectral energy distribution, and Gaia parallax. We use multi-band photometry to confirm that the transit event is on-target and achromatic, and we statistically validate the TESS signal as a transiting exoplanet. We then determine physical properties of the planet through global transit modelling of the TESS and ground-based time-series data. We determine the host to be a metal-poor M4V star, located at a distance of 56 pc, with a sub-solar metallicity \((\mathrm{Fe/H = -0.38 \pm 0.07})\), and a member of the thick disk. The planet is a relatively large sub-Neptune for the M-dwarf planet population, with \(\mathrm{R_p = 2.94 \pm 0.17} \mathrm{R_\oplus}\) and \(\mathrm{P = 3.077}\) d, producing transits of 2% depth. We note the orbit has a non-zero eccentricity to 3\(\mathrm{\sigma}\), prompting questions about the dynamical history of the system. This system is an interesting outcome of planet formation and presents a benchmark for large-planet formation around metal-poor, low-mass stars. The system warrants further study, in particular radial velocity follow-up to determine the planet mass and constrain possible bound companions. Furthermore, TOI-2406 b is a good target for future atmospheric study through transmission spectroscopy, particularly in the category of warm sub-Neptunes.
We report the discovery and characterisation of a super-Earth and a sub-Neptune transiting the bright (\(K=8.8\)), quiet, and nearby (37 pc) M3V dwarf TOI-1266. We validate the planetary nature of ...TOI-1266 b and c using four sectors of TESS photometry and data from the newly-commissioned 1-m SAINT-EX telescope located in San Pedro Mártir (Mexico). We also include additional ground-based follow-up photometry as well as high-resolution spectroscopy and high-angular imaging observations. The inner, larger planet has a radius of \(R=2.37_{-0.12}^{+0.16}\) R\(_{\oplus}\) and an orbital period of 10.9 days. The outer, smaller planet has a radius of \(R=1.56_{-0.13}^{+0.15}\) R\(_{\oplus}\) on an 18.8-day orbit. The data are found to be consistent with circular, co-planar and stable orbits that are weakly influenced by the 2:1 mean motion resonance. Our TTV analysis of the combined dataset enables model-independent constraints on the masses and eccentricities of the planets. We find planetary masses of \(M_\mathrm{p}\) = \(13.5_{-9.0}^{+11.0}\) \(\mathrm{M_{\oplus}}\) (\(<36.8\) \(\mathrm{M_{\oplus}}\) at 2-\(\sigma\)) for TOI-1266 b and \(2.2_{-1.5}^{+2.0}\) \(\mathrm{M_{\oplus}}\) (\(<5.7\) \(\mathrm{M_{\oplus}}\) at 2-\(\sigma\)) for TOI-1266 c. We find small but non-zero orbital eccentricities of \(0.09_{-0.05}^{+0.06}\) (\(<0.21\) at 2-\(\sigma\)) for TOI-1266 b and \(0.04\pm0.03\) (\(<0.10\) at 2-\(\sigma\)) for TOI-1266 c. The equilibrium temperatures of both planets are of \(413\pm20\) K and \(344\pm16\) K, respectively, assuming a null Bond albedo and uniform heat redistribution from the day-side to the night-side hemisphere. The host brightness and negligible activity combined with the planetary system architecture and favourable planet-to-star radii ratios makes TOI-1266 an exquisite system for a detailed characterisation.
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. We report here the discovery and validation of two temperate super-Earths transiting LP 890-9 (TOI-4306, SPECULOOS-2), a relatively low-activity nearby (32 pc) M6V star. The inner planet, LP 890-9b, was first detected by TESS (and identified as TOI-4306.01) based on four sectors of data. Intensive photometric monitoring of the system with the SPECULOOS Southern Observatory then led to the discovery of a second outer transiting planet, LP 890-9c (also identified as SPECULOOS-2c), previously undetected by TESS. The orbital period of this second planet was later confirmed by MuSCAT3 follow-up observations. With a mass of 0.118±0.002 M⊙, a radius of 0.1556±0.0086 R⊙, and an effective temperature of 2850±75 K, LP 890-9 is the second-coolest star found to host planets, after TRAPPIST-1. The inner planet has an orbital period of 2.73 d, a radius of 1.320+0.053−0.027 R⊕, and receives an incident stellar flux of 4.09±0.12 S⊕. The outer planet has a similar size of 1.367+0.055−0.039 R⊕ and an orbital period of 8.46 d. With an incident stellar flux of 0.906 ± 0.026 S⊕, it is located within the conservative habitable zone, very close to its inner limit. Although the masses of the two planets remain to be measured, we estimated their potential for atmospheric characterisation via transmission spectroscopy using a mass-radius relationship and found that, after the TRAPPIST-1 planets, LP 890-9c is the second-most favourable habitable-zone terrestrial planet known so far. The discovery of this remarkable system offers another rare opportunity to study temperate terrestrial planets around our smallest and coolest neighbours.
•Investigation of current obstetric anaesthetic practices in Austria.•Epidural labour analgesia availability is widespread but rates are relatively low.•Intrathecal opioid use is not ...widespread.•Austrian obstetric anaesthetic practice in part differs from US and UK guidelines.
The aim of this study was to describe the current obstetric anaesthetic practices in Austria by performing a comprehensive questionnaire survey.
A questionnaire was sent via email to key anaesthesiologists from obstetric anaesthesia departments of 81 hospitals registered at the Austrian Ministry of Health.
Of 81 departments contacted, 65 (80%), covering 84% of annual births in Austria, responded to the 82-question survey. Epidural analgesia was offered universally, at a rate under 30% in 56 (86%) of respondent hospitals. The caesarean section rate was under 30% in 44 (68%) respondent obstetric units. All respondents provided spinal anaesthesia as the primary anaesthetic technique for elective caesarean section. Three (5%) respondents administered long-acting intrathecal morphine and 18 (28%) respondents did not routinely administer any intrathecal opioid. Wound infiltration for acute postoperative pain control was practiced in two (3%) respondent units. A transversus abdominis plane block was offered as rescue analgesia in 14 (22%) departments. Spinal hypotension was treated using a prophylactic phenylephrine infusion in two (3%) respondent hospitals. Prophylactic antibiotics were administered prior to skin incision by 31 (48%) respondents.
This survey reveals that obstetric anaesthetic practices in Austria differ in part from current European and American guidelines. Findings will direct the national workforce on obstetric anaesthesia that aims to introduce into Austria practice guidelines, based on international collaborations and guideline recommendations.
