In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars (the most common stars in our Galaxy), this model favours the formation of Earth-mass (M % ) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (AU), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars 1-4 . More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 AU from normal stars. Here we report the discovery of a 5.5 15.5 22.7 M % planetary companion at a separation of 2.6 11.5 20.6 AU from a 0.22 10.21 20.11 M ( M-dwarf star, where M ( refers to a solar mass. (We propose to name it OGLE-2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.Gravitational microlensing events can reveal extrasolar planets orbiting the foreground lens stars if the light curves are measured frequently enough to characterize planetary light curve deviations with features lasting a few hours 6-9 . Microlensing is most sensitive to planets in Earth-to-Jupiter-like orbits with semi-major axes in the range 1-5 AU. The sensitivity of the microlensing method to lowmass planets is restricted by the finite angular size of the source stars 10,11 , limiting detections to planets of a few M % for giant source stars, but allowing the detection of planets as small as 0.1M % for main-sequence source stars in the Galactic Bulge. The PLANET collaboration 12 maintains the high sampling rate required to detect low-mass planets while monitoring the most promising of the .500 microlensing events discovered annually by the OGLE collaboration, as well as events discovered by MOA. A decade of pioneering microlensing searches has resulted in the recent detections of two Jupiter-mass extrasolar planets 13,14 with orbital separations of a few AU by the combined observations of the OGLE, MOA, MicroFUN and PLANET collaborations. The absence of perturbations to stellar microlensing events can be used to constrain the presence of planetary lens companions. With large samples of events, upper LETTERS 1 PLANET/RoboNet Collaboration
We combine all available information to constrain the nature of OGLE-2005-BLG-071Lb, the second planet discovered by microlensing and the first in a high-magnification event. These include photometric and astrometric measurements from the Hubble Space Telescope, as well as constraints from higher order effects extracted from the ground-based light curve, such as microlens parallax, planetary orbital motion, and finite-source effects. Our primary analysis leads to the conclusion that the host of Jovian planet OGLE-2005-BLG-071Lb is an M dwarf in the foreground disk with mass M = 0.46 ± 0.04 M , distance D l = 3.2 ± 0.4 kpc, and thick-disk kinematics v LSR ∼ 103 km s −1 . From the best-fit model, the planet has mass M p = 3.8 ± 0.4 M Jupiter , lies at a projected separation r ⊥ = 3.6 ± 0.2AU from its host, and so has an equilibrium temperature of T ∼ 55 K, that is, similar to Neptune. A degenerate model gives similar planetary mass M p = 3.4 ± 0.4 M Jupiter with a smaller projected separation, r ⊥ = 2.1 ± 0.1AU, and higher equilibrium temperature, T ∼ 71 K. These results from the primary analysis suggest that OGLE-2005-BLG-071Lb is likely to be the most massive planet yet discovered that is hosted by an M dwarf. However, the formation of such high-mass planetary companions in the outer regions of M dwarf planetary systems is predicted to be unlikely within the core-accretion scenario. There are a number of caveats to this primary analysis, which assumes (based on real but limited evidence) that the unlensed light coincident with the source is actually due to the lens, that is, the planetary host. However, these caveats could mostly be resolved by a single astrometric measurement a few years after the event.
During the early luteal phase, low progesterone concentrations delay downregulation of endometrial progesterone receptors. This contributes to impaired histotroph production at Day 14 of pregnancy (Beyer et al. 2019 Theriogenology 125, 236-241). Until the beginning of placentation (i.e. Day 37 of pregnancy), nutritional supply of the equine conceptus depends on histotrophy alone. The aim of the present study was to analyse development of the equine conceptus under reduced plasma progesterone concentrations until shortly before placentation. Fertile Haflinger mares (n=11; 4-11 years old) were examined daily by transrectal ultrasonography, and when in oestrus, they were inseminated every 48h until spontaneous ovulation. Mares were randomly assigned to either the treatment group and received the prostaglandin F2α agonist cloprostenol (PGF2α; 125μg) once daily for 3 days after ovulation (Beyer et al. 2019) or the control group and left untreated. After conceptus collection on Day 34, mares were allowed one oestrous cycle for recovery and subsequently assigned to the opposite treatment, thus serving as their own controls. From Day 10 after ovulation, conceptus development including size, uterine fixation, and heartbeat detection was evaluated daily by transrectal ultrasonography. On Day 34, conceptus and fetal membranes were recovered transcervically. The recovered material was weighed, measured, and stored for further analysis. Conceptuses underwent microcomputed tomography that was evaluated by Amira (Thermo Fisher Scientific). Statistical comparison for differences between control and treatment pregnancies was performed by nonparametric Wilcoxon test or chi-square analysis. The day of first visualisation of the conceptus and of the embryo proper and heartbeat did not differ between treatments. Uterine fixation occurred on Day 19.3±0.5 in conceptuses from PGF2α-treated pregnancies but on Day 16.7±0.4 in controls (P<0.05). At 34 days of gestation, the conceptuses from PGF2α-treated mares were smaller (P<0.05) than control conceptuses when measured with ultrasound callipers in utero (maximal length: PGF2α 17.4±0.3mm, control 19.0±0.4mm). Conceptus weight determined after recovery was less in treated pregnancies (PGF2α 2.5±0.2 g; control 3.5±0.3 g; P<0.05). Microcomputed tomography analysis of selected inner organs showed some differences in development. Seven complete pairs of undestroyed conceptuses were available. Mean numbers of 33.4±3.2 and 18.8±7.5 bronchi were detected in control and PGF2α conceptuses, respectively (P<0.05). Heart volume did not differ, but communication between ventricles was detected in only 1/7 control but 5/7 PGF2α conceptuses (P<0.05). The footpad was present in 6/7 control and 0/7 PGF2α conceptuses (P<0.001). In conclusion, subphysiological progesterone concentration during the early luteal phase delays development of the equine conceptus before placentation. The condition may contribute to early conceptus loss in horses, which occurs in up to 20% of pregnancies.
We report a case of a mycotic aneurysm of the internal carotid artery and cerebral hemorrhagic infarction resulting from Aspergillus middle ear infection in a patient with severe aplastic anemia who received unrelated bone marrow transplantation. Although a mycotic aneurysm is a rare complication, and most often fatal, the patient was successfully treated with catheter coil embolization of the internal carotid artery and long‐term systemic antifungal therapy. This case emphasizes the need for the rapid diagnosis of potential fungal involvement of the vascular system and suggests the necessity for aggressive treatment, such as with the modality illustrated in this case.
The mass function and statistics of binaries provide important diagnostics of the star formation process. Despite this importance, the mass function at low masses remains poorly known due to observational difficulties caused by the faintness of the objects. Here we report the microlensing discovery and characterization of a binary lens composed of very low-mass stars just above the hydrogen-burning limit. From the combined measurements of the Einstein radius and microlens parallax, we measure the masses of the binary components of 0.10 ± 0.01 M ⊙ and 0.09 ± 0.01 M ⊙ . This discovery demonstrates that microlensing will provide a method to measure the mass function of all Galactic populations of very low mass binaries that is independent of the biases caused by the luminosity of the population.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.