54 research outputs found

    Discovery of a White Dwarf Companion to HD 159062

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    We report on the discovery of a white dwarf companion to the nearby late G dwarf star, HD 159062. The companion is detected in 14 years of precise radial velocity (RV) data, and in high-resolution imaging observations. RVs of HD 159062 from 2003-2018 reveal an acceleration of −13.3±0.12 ms−1-13.3\pm0.12\ \rm{m s}^{-1}, indicating that it hosts a companion with a long-period orbit. Subsequent imaging observations with the ShaneAO system on the Lick Observatory 3-meter Shane telescope, the PHARO AO system on the Palomar Observatory 5-meter telescope, and the NIRC2 AO system at the Keck II 10-meter telescope reveal a faint companion 2.7'' from the primary star. We performed relative photometry, finding ΔJ=10.09±0.38\Delta J = 10.09 \pm 0.38 magnitudes, ΔKS=10.06±0.22\Delta K_{S} = 10.06 \pm 0.22 magnitudes, and ΔLâ€Č=9.67±0.08\Delta L' = 9.67\pm0.08 magnitudes for the companion from these observations. Analysis of the radial velocities, astrometry, and photometry reveals that the combined data set can only be reconciled for the scenario where HD 159062 B is a white dwarf. A full Bayesian analysis of the RV and imaging data to obtain the cooling age, mass, and orbital parameters of the white dwarf indicates that the companion is an old MB=0.65−0.04+0.12M⊙M_{B} = 0.65^{+0.12}_{-0.04} M_{\odot} white dwarf with an orbital period of P=250−76+130P = 250^{+130}_{-76} years, and a cooling age of τ=8.2−0.5+0.3\tau = 8.2^{+0.3}_{-0.5} Gyr.Comment: 10 pages, 9 figure

    Discovery of a White Dwarf Companion to HD 159062

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    We report on the discovery of a white dwarf companion to the nearby late G dwarf star, HD 159062. The companion is detected in 14 years of precise radial velocity (RV) data, and in high-resolution imaging observations. RVs of HD 159062 from 2003 to 2018 reveal an acceleration of −13.3 ± 0.12 m s^(-1) yr^(-1), indicating that it hosts a companion with a long-period orbit. Subsequent imaging observations with the ShaneAO system on the Lick Observatory 3 m Shane telescope, the PHARO AO system on the Palomar Observatory 5 m telescope, and the NIRC2 AO system at the Keck II 10 m telescope reveal a faint companion 2.”7 from the primary star. We performed relative photometry, finding ΔJ = 10.09 ± 0.38 mag, ΔK_S = 10.06±0.22 mag, and ΔLâ€Č = 9.67±0.08 mag for the companion from these observations. Analysis of the radial velocities, astrometry, and photometry reveals that the combined data set can only be reconciled for the scenario where HD 159062 B is a white dwarf. A full Bayesian analysis of the RV and imaging data to obtain the cooling age, mass, and orbital parameters of the white dwarf indicates that the companion is an old M_B = 0.65^(+0.12)_(−0.04) M_⊙ white dwarf with an orbital period of P = 250^(+130)_(−76) yr, and a cooling age of τ = 8.2^(+0.3)_(−0.5) Gyr

    Citizen science and online data: Opportunities and challenges for snake ecology and action against snakebite

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    The secretive behavior and life history of snakes makes studying their biology, distribution, and the epidemiology of venomous snakebite challenging. One of the most useful, most versatile, and easiest to collect types of biological data are photographs, particularly those that are connected with geographic location and date-time metadata. Photos verify occurrence records, provide data on phenotypes and ecology, and are often used to illustrate new species descriptions, field guides and identification keys, as well as in training humans and computer vision algorithms to identify snakes. We scoured eleven online and two offline sources of snake photos in an attempt to collect as many photos of as many snake species as possible, and attempt to explain some of the inter-species variation in photograph quantity among global regions and taxonomic groups, and with regard to medical importance, human population density, and range size. We collected a total of 725,565 photos—between 1 and 48,696 photos of 3098 of the world's 3879 snake species (79.9%), leaving 781 “most wanted” species with no photos (20.1% of all currently-described species as of the December 2020 release of The Reptile Database). We provide a list of most wanted species sortable by family, continent, authority, and medical importance, and encourage snake photographers worldwide to submit photos and associated metadata, particularly of “missing” species, to the most permanent and useful online archives: The Reptile Database, iNaturalist, and HerpMapper.ISSN:2590-171

    Agricultural Investments and Hunger in Africa Modelling Potential Contributions to SDG 2 - Zero Hunger

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    We use IFPRI’s IMPACT framework of linked biophysical and structural economic models to examine developments in global agricultural production systems, climate change, and food security. Building on related work on how increased investment in agricultural research, resource management, and infrastructure can address the challenges of meeting future food demand, we explore the costs and implications of these investments for reducing hunger in Africa by 2030. This analysis is coupled with a new investment estimation model, based on the perpetual inventory methodology (PIM), which allows for a better assessment of the costs of achieving projected agricultural improvements. We find that climate change will continue to slow projected reductions in hunger in the coming decades—increasing the number of people at risk of hunger in 2030 by 16 million in Africa compared to a scenario without climate change. Investments to increase agricultural productivity can offset the adverse impacts of climate change and help reduce the share of people at risk of hunger in 2030 to five percent or less in Northern, Western, and Southern Africa, but the share is projected to remain at ten percent or more in Eastern and Central Africa. Investments in Africa to achieve these results are estimated to cost about 15 billion USD per year between 2015 and 2030, as part of a larger package of investments costing around 52 billion USD in developing countries

    Understanding the experience of parents of pre-pubescent children with gender identity issues

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    Whilst in recent times there has been an increasing interest in the popular media in families with gender variant children, there is still a paucity of academic research into the experience of parenting a pre-pubescent child with gender identity issues. Gender dysphoria in young children engenders emotive reactions in adults meaning that social workers need to be aware of the various discourses surrounding gender identity in order to work sensitively with families affected. This research explores highly sensitive and intimate aspects of family life, requiring parents to talk and think about difficult issues and explores how it might feel for families to parent a child with gender identity issues. The psychosocial research method of Free Association Narrative Interviews was used in order to gather the data which was then coded and analysed drawing on a constructivist version of grounded theory. Five key themes relating to the process of mourning emerged from the data: loss, uncertainty, ambivalence, being unable to think and acceptance. Recommendations for both social work and clinical practice are also offere

    Constraining the Orbit and Mass of epsilon Eridani b with Radial Velocities, Hipparcos IAD-Gaia DR2 Astrometry, and Multiepoch Vortex Coronagraphy Upper Limits

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    Ï” Eridani is a young planetary system hosting a complex multibelt debris disk and a confirmed Jupiter-like planet orbiting at 3.48 au from its host star. Its age and architecture are thus reminiscent of the early Solar System. The most recent study of Mawet et al., which combined radial-velocity data and Ms-band direct imaging upper limits, started to constrain the planet's orbital parameters and mass, but are still affected by large error bars and degeneracies. Here we make use of the most recent data compilation from three different techniques to further refine Ï” Eridani b's properties: RVs, absolute astrometry measurements from the Hipparcos and Gaia missions, and new Keck/NIRC2 Ms-band vortex coronagraph images. We combine this data in a Bayesian framework. We find a new mass, Mb=0.66−0.09+0.12{M}_{b}={0.66}_{-0.09}^{+0.12} M[SUB]Jup[/SUB], and inclination, i=78.81−22.41∘+29.34i=78.{81}_{-22.41\mathop{}\limits^{^\circ }}^{+29.34} , with at least a factor 2 of improvement over previous uncertainties. We also report updated constraints on the longitude of the ascending node, the argument of the periastron, and the time of periastron passage. With these updated parameters, we can better predict the position of the planet at any past and future epoch, which can greatly help define the strategy and planning of future observations and with subsequent data analysis. In particular, these results can assist the search for a direct detection with JWST and the Nancy Grace Roman Space Telescope's coronagraph instrument.EPIC; NNEx

    Synthesis report of the IPCC Sixth Assessment Report (AR6), Longer report. IPCC.

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    This Synthesis Report (SYR) of the IPCC Sixth Assessment Report (AR6) summarises the state of knowledge of climate change, its widespread impacts and risks, and climate change mitigation and adaptation, based on the peer-reviewed scientific, technical and socio-economic literature since the publication of the IPCC’s Fifth Assessment Report (AR5) in 2014. The assessment is undertaken within the context of the evolving international landscape, in particular, developments in the UN Framework Convention on Climate Change (UNFCCC) process, including the outcomes of the Kyoto Protocol and the adoption of the Paris Agreement. It reflects the increasing diversity of those involved in climate action. This report integrates the main findings of the AR6 Working Group reports1 and the three AR6 Special Reports. It recognizes the interdependence of climate, ecosystems and biodiversity, and human societies; the value of diverse forms of knowledge; and the close linkages between climate change adaptation, mitigation, ecosystem health, human well-being and sustainable development. Building on multiple analytical frameworks, including those from the physical and social sciences, this report identifies opportunities for transformative action which are effective, feasible, just and equitable using concepts of systems transitions and resilient development pathways. Different regional classification schemes are used for physical, social and economic aspects, reflecting the underlying literature. After this introduction, Section 2, ‘Current Status and Trends’, opens with the assessment of observational evidence for our changing climate, historical and current drivers of human-induced climate change, and its impacts. It assesses the current implementation of adaptation and mitigation response options. Section 3, ‘Long-Term Climate and Development Futures’, provides a long-term assessment of climate change to 2100 and beyond in a broad range of socio-economic futures. It considers long-term characteristics, impacts, risks and costs in adaptation and mitigation pathways in the context of sustainable development. Section 4, ‘Near-Term Responses in a Changing Climate’, assesses opportunities for scaling up effective action in the period up to 2040, in the context of climate pledges, and commitments, and the pursuit of sustainable development. Based on scientific understanding, key findings can be formulated as statements of fact or associated with an assessed level of confidence using the IPCC calibrated language5 . The scientific findings are drawn from the underlying reports and arise from their Summary for Policymakers (hereafter SPM), Technical Summary (hereafter TS), and underlying chapters and are indicated by {} brackets. Figure 1.1 shows the Synthesis Report Figures Key, a guide to visual icons that are used across multiple figures within this report
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