A new L-dwarf member of the moderately metal-poor triple system HD 221356

We report on the discovery of a fourth component in the HD 221356 star system, previously known to be formed by an F8V, slightly metal-poor primary ([Fe/H]=-0.26), and a distant M8V+L3V pair. In our ongoing common proper motion search based on VISTA Hemisphere Survey (VHS) and 2MASS catalogues, we have detected a faint (J=13.76+/-0.04 mag) co-moving companion of the F8 star located at angular separation of 12.13+/-0.18 arcsec (position angle of 221.8+/-1.7), corresponding to a projected distance of ~312 AU at 26 pc. Near-infrared spectroscopy of the new companion, covering the 1.5-2.4 micron wavelength range with a resolving power of R~600, indicates an L1+/-1 spectral type. Using evolutionary models the mass of the new companion is estimated at ~0.08 solar masses, which places the object close to the stellar-substellar borderline. This multiple system provides an interesting example of objects with masses slightly above and below the hydrogen burning mass limit. The low mass companions of HD 221356 have slightly bluer colours than field dwarfs with similar spectral type, which is likely a consequence of the sub-solar metallicity of the system.Comment: 7 pages, 4 figures, accepted for publication in MNRA

Candidate free-floating super-Jupiters in the young sigma Orionis open cluster

Free-floating substellar candidates with estimated theoretical masses of as low as ~5 Jupiter masses have been found in the ~3 Myr old sigma Orionis open cluster. As the overlap with the planetary mass domain increases, the question of how these objects form becomes important. The determination of their number density and whether a mass cut-off limit exists is crucial to understanding their formation. We propose to search for objects of yet lower masses in the cluster and determine the shape of the mass function at low mass. Using new- and (re-analysed) published IZJHKs[3.6]-[8.0]-band data of an area of 840 arcmin2, we performed a search for LT-type cluster member candidates in the magnitude range J=19.5-21.5 mag, based on their expected magnitudes and colours. Besides recovering the T type object S Ori 70 and two other known objects, we find three new cluster member candidates, S Ori 72-74, with J=21 mag and within 12 arcmin of the cluster centre. They have theoretical masses of 4 (-2,+3) M_Jup and are among the least massive free-floating objects detected by direct imaging outside the Solar System. The photometry in archival Spitzer [3.6]-[5.8]-band images infers that S Ori 72 is an L/T transition candidate and S Ori 73 a T-type candidate, following the expected cluster sequence in the mid-infrared. Finally, the L-type candidate S Ori 74 with lower quality photometry is located at 11.8 arcsec (~4250 AU) of a stellar member of sigma Orionis and could be a companion. After contaminant correction in the area complete to J=21.1 mag, we estimate that there remain between zero and two cluster members in the mass interval 6-4 M_Jup. Our result suggests a possible turnover in the substellar mass spectrum below ~6 Jupiter masses, which could be investigated further by wider and deeper photometric surveys.Comment: 15 pages, 13 figures, 5 tables, and appendix containing 5 figures; accepted for publication in AA; v2: 2 minor corrections, in abstract and sect. 2.

The PLATO 2.0 mission

PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence) providing a wide field-of-view (2232 deg 2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete our knowledge of planet diversity for low-mass objects, - correlate the planet mean density-orbital distance distribution with predictions from planet formation theories,- constrain the influence of planet migration and scattering on the architecture of multiple systems, and - specify how planet and system parameters change with host star characteristics, such as type, metallicity and age. The catalogue will allow us to study planets and planetary systems at different evolutionary phases. It will further provide a census for small, low-mass planets. This will serve to identify objects which retained their primordial hydrogen atmosphere and in general the typical characteristics of planets in such low-mass, low-density range. Planets detected by PLATO 2.0 will orbit bright stars and many of them will be targets for future atmosphere spectroscopy exploring their atmosphere. Furthermore, the mission has the potential to detect exomoons, planetary rings, binary and Trojan planets. The planetary science possible with PLATO 2.0 is complemented by its impact on stellar and galactic science via asteroseismology as well as light curves of all kinds of variable stars, together with observations of stellar clusters of different ages. This will allow us to improve stellar models and study stellar activity. A large number of well-known ages from red giant stars will probe the structure and evolution of our Galaxy. Asteroseismic ages of bright stars for different phases of stellar evolution allow calibrating stellar age-rotation relationships. Together with the results of ESA's Gaia mission, the results of PLATO 2.0 will provide a huge legacy to planetary, stellar and galactic science

Discriminant analyses of peanut allergy severity scores

Peanut allergy is one of the most prevalent food allergies. The possibility of a lethal accidental exposure and the persistence of the disease make it a public health problem. Evaluating the intensity of symptoms is accomplished with a double blind placebo-controlled food challenge (DBPCFC), which scores the severity of reactions and measures the dose of peanut that elicits the first reaction. Since DBPCFC can result in life-threatening responses, we propose an alternate procedure with the long-term goal of replacing invasive allergy tests. Discriminant analyses of DBPCFC score, the eliciting dose and the first accidental exposure score were performed in 76 allergic patients using 6 immunoassays and 28 skin prick tests. A multiple factorial analysis was performed to assign equal weights to both groups of variables, and predictive models were built by cross-validation with linear discriminant analysis, k -nearest neighbours, classification and regression trees, penalized support vector machine, stepwise logistic regression and AdaBoost methods. We developed an algorithm for simultaneously clustering eliciting dose values and selecting discriminant variables. Our main conclusion is that antibody measurements offer information on the allergy severity, especially those directed against rAra-h1 and rAra-h3 . Further independent validation of these results and the use of new predictors will help extend this study to clinical practices.

Spectroscopic follow-up of L- and T-type proper-motion member candidates in the Pleiades

International audienc

Alveolar echinococcosis is increasing in Southern Belgium: a report of the Belgian National Reference Laboratory for Echinococcosis (BNRLE) and clinical experience of ECHINO- Liege

peer reviewedIntroduction Alveolar echinococcosis (AE) is endemic in Southern Belgium where up to 50% of the red foxes might be infected and spread Echinococcus eggs in the environment. In humans, the primary target organ of AE is the liver, in which AE grows as a parasitic tumor and might later develop in other organs as a malignancy and be lethal. In response to the increasing number of AE cases, a multidisciplinary group (ECHINO-Liege) was created in CHU Liege to improve AE management and to discuss the AE cases. In addition, on the top of a retrospective AE registry, ECHINO-Liege is prospectively building a database (ECHINO-Base) and a biobank (ECHINO-Bank) of AE patients managed in CHU Liege, after EC approval and informed consent. Finally, since 2021, the Belgian National Reference Laboratory for Echinococcosis (BNRLE) is based in the department of Clinical Microbiology of CHU Liege. Aim The aim of this study was to report the actual epidemiological and clinical situation on AE in Belgium, using the BNRLE data and the clinical experience of ECHINO-Liege. Methods All Belgian clinical laboratories were asked to fill epidemiological forms on AE cases detected in 2021 and 2022. All cases confirmed by serology (immunoblot) and/or PCR and/or histology (proved cases) or without microbiological confirmation (probable and possible cases) were included. These cases were added to the retrospective series already published in 2018 and to the cases discussed during the regular meetings of ECHINO-Liege. Results AE was newly diagnosed and reported to BNRLE in 16 patients in the time-period of 2 years, added to the 36 patients previously registered (total: 52 patients, 29M/23F) (mean age: 60y, 19-89). Most patients were born and lived in Wallonia or the Brussels area. All cases but 2 are considered contracted in Belgium (1 in France and 1 in Luxembourg). 31 patients underwent liver resection and 1 liver transplantation. Conclusions AE appears to be spreading in Southern Belgium. The authorities should be aware of this public health issue. The radiologists and gastroenterologists should be informed of this diagnosis possibility in case of liver tumor. A national multicentric survey will be soon initiated as a collaboration between the different hospitals in the whole country