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We present a multiwavelength analysis to reveal the nature of the enigmatic T Tauri triple star system. New optical and infrared measurements are coupled with archival X-ray, UV, and millimeter data sets to show the morphologies of disk material and outflow kinematics. A dark lane of obscuring material is seen in silhouette in several emission lines and in model-subtracted ALMA millimeter continuum dust residuals near the position of T Tau Sa+Sb, revealing the attenuating circumbinary ring around T Tau S. The flux variability of T Tau S is linked in part to the binary orbit; T Tau Sb brightens near orbital apastron as it emerges from behind circumbinary material. Outflow diagnostics confirm that T Tau N powers the blueshifted western outflow, and the T Tau S binary drives the northwest-southeastern flow. Analysis of the southern outflow shows periodic arcs ejected from the T Tau system. Correlation of these arc locations and tangential kinematics with the orbit timing suggests that launch of the last four southern outflow ejections is contemporaneous with, and perhaps triggered by, the T Tau Sa+Sb binary periastron passage. We present a geometry of the T Tau triple that has the southern components foreground to T Tau N, obscured by a circumbinary ring, with misaligned disks and interacting outflows. Particularly, a wind from T Tauri Sa that is perpendicular to its circumstellar disk might interact with the circumbinary material, which may explain conflicting high-contrast measurements of the system outflows in the literature. T Tauri is an important laboratory for understanding early dynamical processes in young multiple systems. We discuss the historical and future characteristics of the system in this context. [ABSTRACT FROM AUTHOR]

Extreme outbursts in young stars may be a common stage of pre-main-sequence stellar evolution. These outbursts, caused by enhanced accretion and accompanied by increased luminosity, can also strongly impact the evolution of the circumstellar environment. We present Atacama Large Millimeter Array (ALMA) and Very Large Array observations of EX Lupi, a prototypical outburst system, at 100, 45, and 15 GHz. We use these data, along with archival ALMA 232 GHz data, to fit radiative transfer models to EX Lupi's circumstellar disk in its quiescent state following the extreme outburst in 2008. The best-fit models show a compact disk with a characteristic dust radius of 45 au and a total mass of 0.01 M⊙. Our modeling suggests grain growth to sizes of at least 3 mm in the disk, possibly spurred by the recent outburst, and an ice line that has migrated inward to 0.2–0.3 au post-outburst. At 15 GHz, we detected significant emission over the expected thermal disk emission which we attribute primarily to stellar (gyro)synchrotron and free–free disk emission. Altogether, these results highlight what may be a common impact of outbursts on the circumstellar dust. [ABSTRACT FROM AUTHOR]

Context. ALMA high angular resolution observations of the dust and CO emission have already revealed signatures of protoplanets embedded in protoplanetary disks. These detections are around single T Tauri stars, while exoplanet surveys reveal that planets can also form in binary (or multiple) systems, either in circumstellar or circumbinary orbits. Aims. We searched for indirect evidence for planet formation in the multiple system GG Tau A, which harbors the most massive circumbinary disk among T Tauri stars. Methods. We performed CO(2-1) ALMA Cycle 6 observations of GG Tau A at 0.300 resolution. The images confirm the "hot spot" detected at higher frequencies, but also reveal prominent spiral-like features. We modeled these features using the analytic prescription for the linear perturbation regime induced by low-mass planets. Results. The brightest spiral is well reproduced by a density wave excited by a protoplanet (GG Tau Ac) at the hot-spot location (290 au), just outside the dust ring. The absence of a clear gap (in gas or dust) at the planet location implies that its mass is significantly lower than that of Jupiter, i.e., of about the mass of Neptune or lower. Furthermore, other prominent (trailing) spiral patterns can be represented by adding one (or more) planet(s) at larger orbital radii, with the most obvious candidate located near the 2:1 mean-motion resonance with GG Tau Ac. Conclusions. The (proto-)planet GG Tau Ac appears to externally confine the ring in a stable configuration, explaining its high mass. Our results also suggest that planets similar in mass to Neptune may form in dense circumbinary disks orbiting (wide) binary stars. In the GG Tau case, orbital resonances appear to play an important role in shaping this multiple circumbinary planet system. [ABSTRACT FROM AUTHOR]

Context. The study of gas-rich debris discs is fundamental to characterising the transition between protoplanetary discs and debris discs. Aims. We determine the physical parameters of the brightest gas-rich debris disc orbiting HD 141569A. Methods. We analyse images from the NOrthern Extended Millimeter Array (NOEMA)1 and the Atacama Large Millimeter/submillimeter Array (ALMA) in 12CO, 13CO J = 2→1, and 13CO J = 1→0 transitions. We incorporate ALMA archival data of the 12CO J = 3→2 transition and present continuum maps at 0.87, 1.3, and 2.8 mm. We use simple parametric laws with the Diskfit code and MCMC exploration to characterise the gas disc parameters and report a first attempt to characterise its chemical content with IRAM-30 m. Results. The continuum emission is equally shared between a compact (≤50 au) and a smooth, extended dust component (~350 au). Large millimetre grains seem to dominate the inner regions, while the dust spectral index is marginally larger in the outer region. The 12CO is optically thick, while 13CO is optically thin with 13CO ~ 0.15 (C18O is not detected). The 13CO surface density is constrained to be one order of magnitude smaller than around younger Herbig Ae stars, and we derive a gas mass M12CO = 10-1M®. We confirm the presence of a small CO cavity (RCO = 17 × 3 au), and find a possibly larger radius for the optically thin 13CO J = 2→1 transition (35 × 5 au). We show that the observed CO brightness asymmetry is coincident with the complex ring structures discovered with VLT/SPHERE in the inner 90 au. The 12CO temperature T0(100 au) ~ 30K is lower than expected for a Herbig A0 star, and could be indicative of subthermal excitation. Conclusions. With the largest amount of dust and gas among hybrid discs, HD 141569A shows coincident characteristics of both protoplanetary discs (central regions), and debris discs at large distance. Together with its morphological characteristics and young age, it appears to be a good candidate to witness the transient phase of gas dissipation, with an apparently large gas-to-dust ratio (G=D > 100) favouring a faster evolution of dust grains. [ABSTRACT FROM AUTHOR]

Abstract: The IRAM Plateau de Bure Interferometer has been used to map the CO(1–0) rotational line in Mars'' middle atmosphere. Absolute winds and thermal profiles were retrieved during the 1999, 2001, 2003 and 2005 planet''s oppositions. The observations sampled various seasons (, 196, 262, 317 and 322), and different dust situations (clear, global storm, regional storm). The absolute winds were derived by measuring directly the Doppler lineshifts. The main zonal circulation near 50 km is dominated by strong retrograde winds, with typical velocities of 70–170 m/s, strongly varying seasonally, latitudinally, and longitudinally (in particular between morning and evening). Comparison of the retrieved temperature with a general circulation model indicates that the model often underestimates the temperatures in the middle (20–50 km) atmosphere, and overestimates them above 50 km. [Copyright &y& Elsevier]

Background: Patients on peritoneal dialysis (PD) can be assisted by a nurse or a family member and treated either by automated PD (APD) or continuous ambulatory PD (CAPD). The aim of this study was to evaluate the effect of PD modality and type of assistance on the risk of transfer to haemodialysis (HD) and on the peritonitis risk in assisted PD patients., Method: This was a retrospective study based on data from the French Language PD Registry. All adults starting assisted PD in France between 2006 and 2015 were included. Events of interest were transfer to HD, peritonitis and death. Cox regression models were used for statistical analysis., Results: Among the 12,144 incident patients who started PD in France during the study period, 6,167 were assisted. There were 5,060 nurse-assisted and 1,095 family-assisted PD patients. Overall, 5,171 were treated by CAPD and 996 by APD. In multivariate analysis, CAPD, compared to APD, was not associated with the risk of transfer to HD (cause specific hazard ratios [cs-HR] 0.96 [95% CI 0.84-1.09]). Patients on nurse-assisted PD had a lower risk of transfer to HD than family assisted PD patients (cs-HR 0.85 [95% CI 0.75-0.97]). Neither PD modality nor type of assistance were associated with peritonitis risk., Conclusions: In assisted PD, technique survival was not associated with PD modality. Nurse-assisted patients had a lower risk of transfer to HD than family assisted patients. Peritonitis risk was not influenced either by PD modality, or by type of assistance. Both APD and CAPD should be offered to assisted-PD patients., (© 2018 S. Karger AG, Basel.)

The formation of planets around binary stars may be more difficult than around single stars. In a close binary star (with a separation of less than a hundred astronomical units), theory predicts the presence of circumstellar disks around each star, and an outer circumbinary disk surrounding a gravitationally cleared inner cavity around the stars. Given that the inner disks are depleted by accretion onto the stars on timescales of a few thousand years, any replenishing material must be transferred from the outer reservoir to fuel planet formation (which occurs on timescales of about one million years). Gas flowing through disk cavities has been detected in single star systems. A circumbinary disk was discovered around the young low-mass binary system GG Tau A (ref. 7), which has recently been shown to be a hierarchical triple system. It has one large inner disk around the single star, GG Tau Aa, and shows small amounts of shocked hydrogen gas residing within the central cavity, but other than a single weak detection, the distribution of cold gas in this cavity or in any other binary or multiple star system has not hitherto been determined. Here we report imaging of gas fragments emitting radiation characteristic of carbon monoxide within the GG Tau A cavity. From the kinematics we conclude that the flow appears capable of sustaining the inner disk (around GG Tau Aa) beyond the accretion lifetime, leaving time for planet formation to occur there. These results show the complexity of planet formation around multiple stars and confirm the general picture predicted by numerical simulations.

The z=2.39 radio galaxy 53W002 lies in a cluster of Lyalpha emission-line objects and may itself be undergoing a major burst of star formation. CO (3-2) emission, at 102 GHz, was detected from 53W002 in 1997 by Scoville et al., who also reported a possible 30 kpc extension and velocity gradient suggesting a rotating gaseous disk. In this Letter, we present new interferometric CO (3-2) observations that confirm the previous line detection with improved signal-to-noise ratio, but show no evidence for source extension or velocity gradient. The compact nature of the CO source and the molecular mass found in this object are similar to luminous infrared galaxies and other active galactic nuclei previously studied.

Galaxies are believed to have formed a large proportion of their stars in giant bursts of star formation early in their lives, but when and how this took place are still very uncertain. The presence of large amounts of dust in quasars and radio galaxies at redshifts z > 4 shows that some synthesis of heavy elements had already occurred at this time. This implies that molecular gas--the building material of stars--should also be present, as it is in galaxies at lower redshifts (z approximately = 2.5, refs 7-10). Here we report the detection of emission from dust and carbon monoxide in the radio-quiet quasar BR1202 - 0725, at redshift z = 4.69. Maps of these emissions reveal two objects, separated by a few arc seconds, which could indicated either the presence of a companion to the quasar or gravitational lensing of the quasar itself. Regardless of the precise interpretation of the maps, the detection of carbon monoxide confirms the presence of a large mass of molecular gas in one of the most distant galaxies known, and shows that conditions conducive to huge bursts of star formation existed in the very early Universe.