ABSTRACT
Photometry at 3.4 and 4.6 ${\mu m}$ of 128 Population I WC type Wolf–Rayet stars in the Galaxy and 12 in the Large Magellanic Cloud (LMC) observed in the WISE NEOWISE-R survey was searched ...for evidence of circumstellar dust emission and its variation. Infrared spectral energy distributions (SEDs) were assembled, making use of archival r, i, Z, and Y photometry to determine reddening and stellar wind levels for the WC stars found in recent IR surveys and lacking optical photometry. From their SEDs, 10 apparently non-variable stars were newly identified as dust makers, including three, WR 102-22, WR 110-10, and WR 124-10, having subtype earlier than WC8–9, the first such stars to show this phenomenon. The 11 stars found to show variable dust emission include six new episodic dust makers, WR 47c, WR 75-11, WR 91-1, WR 122-14, and WR 125-1 in the Galaxy and HD 38030 in the LMC. Of previously known dust makers, NEOWISE-R photometry of WR 19 captured its rise to maximum in 2018 confirming the 10.1-yr period, that of WR 125 the beginning of a new episode of dust formation suggesting a period near 28.3 yr. while that of HD 36402 covered almost a whole period and forced revision of it to 5.1 yr.
The recurrent nova M31N 2008-12a experiences annual eruptions, contains a near-Chandrasekhar-mass white dwarf, and has the largest mass accretion rate in any nova system. In this paper, we present ...Hubble Space Telescope (HST) WFC3/UVIS photometry of the late decline of the 2015 eruption. We couple these new data with archival HST observations of the quiescent system and Keck spectroscopy of the 2014 eruption. The late-time photometry reveals a rapid decline to a minimum luminosity state, before a possible recovery/rebrightening in the run up to the next eruption. Comparison with accretion disk models supports the survival of the accretion disk during the eruptions, and uncovers a quiescent disk mass accretion rate of the order of 10 − 6 M yr − 1 , which may rise beyond 10 − 5 M yr − 1 during the super-soft source phase-both of which could be problematic for a number of well-established nova eruption models. Such large accretion rates, close to the Eddington limit, might be expected to be accompanied by additional mass loss from the disk through a wind and even through collimated outflows. The archival HST observations, combined with the disk modeling, provide the first constraints on the mass donor: L donor = 103 − 11 + 12 L , R donor = 14.14 − 0.47 + 0.46 R , and T eff , donor = 4890 110 K, which may be consistent with an irradiated M31 red-clump star. Such a donor would require a system orbital period 5 days. Our updated analysis predicts that the M31N 2008-12a WD could reach the Chandrasekhar mass in < 20 kyr.
Abstract
We report on multiwavelength observations of nova Small Magellanic Cloud Nova 2016-10a. The present observational set is one of the most comprehensive for any nova in the Small Magellanic ...Cloud, including low-, medium-, and high-resolution optical spectroscopy and spectropolarimetry from Southern African Large Telescope, Folded Low-Order Yte-Pupil Double-Dispersed Spectrograph, and Southern Astrophysical Research; long-term Optical Gravitational Lensing Experiment V- and I-bands photometry dating back to 6 yr before eruption; Small and Moderate Aperture Research Telescope System optical and near-IR photometry from ∼11 d until over 280 d post-eruption; Swift satellite X-ray and ultraviolet observations from ∼6 d until 319 d post-eruption. The progenitor system contains a bright disc and a main sequence or a sub-giant secondary. The nova is very fast with t2 ≃ 4.0 ± 1.0 d and t3 ≃ 7.8 ± 2.0 d in the V band. If the nova is in the SMC, at a distance of ∼61 ± 10 kpc, we derive MV, max ≃ −10.5 ± 0.5, making it the brightest nova ever discovered in the SMC and one of the brightest on record. At day 5 post-eruption the spectral lines show a He/N spectroscopic class and an Full Width at Half Maximum of ∼3500 km s−1, indicating moderately high ejection velocities. The nova entered the nebular phase ∼20 d post-eruption, predicting the imminent super-soft source turn-on in the X-rays, which started ∼28 d post-eruption. The super-soft source properties indicate a white dwarf mass between 1.2 and 1.3 M⊙ in good agreement with the optical conclusions.
A revision of the 2008 British Association for Psychopharmacology evidence-based guidelines for treating depressive disorders with antidepressants was undertaken in order to incorporate new evidence ...and to update the recommendations where appropriate. A consensus meeting involving experts in depressive disorders and their management was held in September 2012. Key areas in treating depression were reviewed and the strength of evidence and clinical implications were considered. The guidelines were then revised after extensive feedback from participants and interested parties. A literature review is provided which identifies the quality of evidence upon which the recommendations are made. These guidelines cover the nature and detection of depressive disorders, acute treatment with antidepressant drugs, choice of drug versus alternative treatment, practical issues in prescribing and management, next-step treatment, relapse prevention, treatment of relapse and stopping treatment. Significant changes since the last guidelines were published in 2008 include the availability of new antidepressant treatment options, improved evidence supporting certain augmentation strategies (drug and non-drug), management of potential long-term side effects, updated guidance for prescribing in elderly and adolescent populations and updated guidance for optimal prescribing. Suggestions for future research priorities are also made.
The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global ...scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.
Abstract
The long-period, highly eccentric Wolf-Rayet star binary system WR 140 has exceptionally well-determined orbital and stellar parameters. Bright, variable X-ray emission is generated in ...shocks produced by the collision of the winds of the WC7pd+O5.5fc component stars. We discuss the variations in the context of the colliding-wind model using broadband spectrometry from the RXTE, Swift, and NICER observatories obtained over 20 yr and nearly 1000 observations through three consecutive 7.94 yr orbits, including three periastron passages. The X-ray luminosity varies as expected with the inverse of the stellar separation over most of the orbit; departures near periastron are produced when cooling shifts to excess optical emission in C
iii
λ
5696 in particular. We use X-ray absorption to estimate mass-loss rates for both stars and to constrain the system morphology. The absorption maximum coincides closely with the inferior conjunction of the WC star and provides evidence of the ion-reflection mechanism that underlies the formation of collisionless shocks governed by magnetic fields probably generated by the Weibel instability. Comparisons with
K
-band emission and He
i
λ
10830 absorption show that both are correlated after periastron with the asymmetric X-ray absorption. Dust appears within a few days of periastron, suggesting formation within shocked gas near the stagnation point. The X-ray flares seen in
η
Car have not occurred in WR 140, suggesting the absence of large-scale wind inhomogeneities. Relatively constant soft emission revealed during the X-ray minimum is probably not from recombining plasma entrained in outflowing shocked gas.
Empirically supported psychological treatments have been developed for a range of psychiatric disorders but there is evidence that patients are not receiving them in routine clinical care. ...Furthermore, even when patients do receive these treatments there is evidence that they are often not well delivered. The aim of this paper is to identify the barriers to the dissemination of evidence-based psychological treatments and then propose ways of overcoming them, hence potentially bridging the gap between research findings and clinical practice.
We present the result of a search of the Milagro sky map for spatial correlations with sources from a subset of the recent Fermi Bright Source List (BSL). The BSL consists of the 205 most significant ...sources detected above 100 MeV by the Fermi Large Area Telescope. We select sources based on their categorization in the BSL, taking all confirmed or possible Galactic sources in the field of view of Milagro. Of the 34 Fermi sources selected, 14 are observed by Milagro at a significance of 3 standard deviations or more. We conduct this search with a new analysis which employs newly optimized gamma-hadron separation and utilizes the full eight-year Milagro data set. Milagro is sensitive to gamma rays with energy from 1 to 100 TeV with a peak sensitivity from 10 to 50 TeV depending on the source spectrum and declination. These results extend the observation of these sources far above the Fermi energy band. With the new analysis and additional data, multi-TeV emission is definitively observed associated with the Fermi pulsar, J2229.0+6114, in the Boomerang pulsar wind nebula (PWN). Furthermore, an extended region of multi-TeV emission is associated with the Fermi pulsar, J0634.0+1745, the Geminga pulsar.
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