Context. Low and intermediate mass stars lose a significant fraction of their mass through a dust-driven wind during the Asymptotic Giant Branch (AGB) phase. Recent studies show that winds from late-type stars are far from being smooth. Mass-loss variations occur on different time scales, from years to tens of thousands of years. The variations appear to be particularly prominent towards the end of the AGB evolution. The occurrence, amplitude and time scale of these variations are still not well understood. Aims. The goal of our study is to gain insight into the structure of the circumstellar envelope (CSE) of WX Psc and map the possible variability of the late-AGB mass-loss phenomenon. Methods. We have performed an in-depth analysis of the extreme infrared AGB star WX Psc by modeling (1) the CO J = 1-0 through 7-6 rotational line profiles and the full spectral energy distribution (SED) ranging from 0.7 to 1300 m. We hence are able to trace a geometrically extended region of the CSE. Results. Both mass-loss diagnostics bear evidence of the occurrence of mass-loss modulations during the last similar to 2000 yr. In particular, WX Psc went through a high mass-loss phase (M similar to 5 x 10(-5) M-circle dot/yr) some 800 yr ago. This phase lasted about 600 yr and was followed by a long period of low mass loss (M similar to 5 x 10(-5) M-circle dot/yr). The present day mass-loss rate is estimated to be similar to 6 x 10-(6) M-circle dot/yr. Conclusions. The AGB star WX Psc has undergone strong mass-loss rate variability on a time scale of several hundred years during the last few thousand years. These variations are traced in the strength and profile of the CO rotational lines and in the SED. We have consistently simulated the behaviour of both tracers using radiative transfer codes that allow for non-constant mass-loss rates.

We report the discovery of a high CO (J = 3-2)/CO (J = 1-0 ) ratio gas with an arclike distribution ("high ratio gas arc") surrounding the central star cluster of the supergiant H ii region NGC 604 in the nearby spiral galaxy M33, based on multi- J CO observations of a 5' x 5' region of NGC 604 conducted using the ASTE 10 m and NRO 45 m telescopes. The discovered " high- ratio gas arc" extends to the southeast- northwest direction with a size of similar to 200 pc. The western part of the high- ratio gas arc closely coincides with the shells of the H (II) regions traced by Ha and radio continuum peaks. The CO (J = 3-2)/CO (J = 1-0 ) ratio, R3-2/1-0, ranges between 0.3 and 1.2 in the observed region, and the R3-2/1-0 values of the high- ratio gas arc are around or higher than unity, indicating very warm (T-kin >= 60 K) and dense (n(H2) >= 10(3) -10(4) cm(-3)) conditions of the high- ratio gas arc. We suggest that the dense gas formation and second-generation star formation occur in the surrounding gas compressed by the stellar wind and/or supernova of the first-generation stars of NGC 604, i. e., the central star cluster of NGC 604.

We present results of the (CO)-C-12 (1-0) mosaic observations of the nearby barred-spiral galaxy M 83 obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). The total flux is recovered by combining the ALMA data with single-dish data obtained using the Nobeyama 45 m telescope. The combined map covers a similar to 13 kpc(2) field that includes the galactic center, eastern bar, and spiral arm with a resolution of 2.'' 03 x 1.'' 15 (similar to 45 pc x similar to 25 pc). With a resolution comparable to typical sizes of giant molecular clouds (GMCs), the CO distribution in the bar and arm is resolved into many clumpy peaks that form ridge-like structures. Remarkably, in the eastern arm, the CO peaks form two arc-shaped ridges that run along the arm and exhibit a distinct difference in the activity of star formation: the one on the leading side has numerous H-II regions associated with it, whereas the other one on the trailing side has only a few. To see whether GMCs form stars with uniform star formation efficiency (SFE) per free-fall time (SFEff), GMCs are identified from the data cube and then cross-matched with the catalog of H-II regions to estimate the star formation rate for each of them. 179 GMCs with a median mass of 1.6 x 106 M-circle dot are identified. The mass-weighted average SFEff of the GMCs is similar to 9.4 x 10(-3), which is in agreement with models of turbulence regulated star formation. Meanwhile, we find that SFEff is not universal within the mapped region. In particular, one of the arm ridges shows a high SFEff with a mass-weighted value of similar to 2.7 x 10(-2), which is higher by more than a factor of 5 compared to the inter-arm regions. This large regional variation in SFEff favors the recent interpretation that GMCs do not form stars at a constant rate within their lifetime.

J/psi suppression has long been considered a sensitive signature of the formation of the Quark-Gluon Plasma (QGP) in relativistic heavy-ion collisions. In this letter, we present the first measurement of inclusive J/psi production at mid-rapidity through the dimuon decay channel in Au+Au collisions at root s(NN) =3D 200 GeV with the STAR experiment. These measurements became possible after the installation of the Muon Telescope Detector was completed in 2014. The J/psi yields are measured in a wide transverse momentum (p(T)) range of 0.15 GeV/c to 12 GeV/c from central to peripheral collisions. They extend the kinematic reach of previous measurements at RHIC with improved precision. In the 0-10% most central collisions, the J/psi yield is suppressed by a factor of approximately 3 for p(T) > 5 GeV/c relative to that in p + p collisions scaled by the number of binary nucleon-nucleon collisions. The J/psi nuclear modification factor displays little dependence on p(T) in all centrality bins. Model calculations can qualitatively describe the data, providing further evidence for the color-screening effect experienced by J/psi mesons in the QGP.(C) 2019 The Author(s). Published by Elsevier B.V.

High angular resolution and sensitive aperture synthesis observations of CS (J = 2-1) and CS (J = 3-2) emissions toward L1551 NE, the second brightest protostar in the Taurus molecular cloud, made with the Nobeyama Millimeter Array are presented. L1551 NE is categorized as a Class 0 object deeply embedded in the redshifted outflow lobe of L1551 IRS 5. Previous studies of the L1551 NE region in CS emission revealed the presence of shell-like components open toward L1551 IRS 5, which seem to trace low-velocity shocks in the swept-up shell driven by the outflow from L1551 IRS 5. In this study, significant CS emission around L1551 NE was detected at the eastern tip of the swept-up shell from V-lsr = 5.3 to 10.1 km s(-1), and the total mass of the dense gas is estimated to be 0.14 +/- 0.02 M-.. In addition, the following new structures were successfully revealed: a compact disklike component with a size of approximate to 1000 AU just at L1551 NE, an arc-shaped structure around L1551 NE, open toward L1551 NE, with a size of similar to 5000 AU, i. e., a bow shock, and a distinct velocity gradient of the dense gas, i. e., deceleration along the outflow axis of L1551 IRS 5. These features suggest that the CS emission traces the postshocked region where the dense gas associated with L1551 NE and the swept-up shell of the outflow from L1551 IRS 5 interact. Since the age of L1551 NE is comparable to the timescale of the interaction, it is plausible that the formation of L1551 NE was induced by the outflow impact. The compact structure of L1551 NE with a tiny envelope was also revealed, suggesting that the outer envelope of L1551 NE has been blown off by the outflow from L1551 IRS 5.

The circumstellar environment of the AGB star L-2 Puppis was observed with ALMA in cycle 3, with a resolution of 15 x 18 mas. The molecular emission shows a differentially rotating disk, inclined to a nearly edge-on position. In the first paper in this series ( Paper I) the molecular emission was analysed to accurately deduce the motion of the gas in the equatorial regions of the disk. In this work we model the optically thick (CO)-C-12 J =3D 3-2 and the optically thin (CO)-C-13 J =3D 3-2 rotational transition to constrain the physical conditions in the disk. To realise this effort we make use of the 3D NLTE radiative transfer code LIME. The temperature structure and velocity structure show a high degree of complexity, both radially and vertically. The radial H-2 density profile in the disk plane is characterised by a power law with a slope of -3:1. We find a (CO)-C-12 over (CO)-C-13 abundance ratio of 10 inside the disk. Finally, estimations of the angular momentum in the disk surpass the expected available angular momentum of the star, strongly supporting the indirect detection of a compact binary companion reported in Paper I. We estimate the mass of the companion to be around 1 Jupiter mass.