Single-lens mass measurement in the high-magnification microlensing event Gaia 19bld located in the Galactic disc

CONTEXT: Microlensing provides a unique opportunity to detect non-luminous objects. In the rare cases that the Einstein radius θ_{E} and microlensing parallax π_{E} can be measured, it is possible to determine the mass of the lens. With technological advances in both ground- and space-based observatories, astrometric and interferometric measurements are becoming viable, which can lead to the more routine determination of θ_{E} and, if the microlensing parallax is also measured, the mass of the lens. AIMS: We present the photometric analysis of Gaia19bld, a high-magnification (A ≈ 60) microlensing event located in the southern Galactic plane, which exhibited finite source and microlensing parallax effects. Due to a prompt detection by the Gaia satellite and the very high brightness of I = 9.05 mag at the peak, it was possible to collect a complete and unique set of multi-channel follow-up observations, which allowed us to determine all parameters vital for the characterisation of the lens and the source in the microlensing event. METHODS: Gaia19bld was discovered by the Gaia satellite and was subsequently intensively followed up with a network of ground-based observatories and the Spitzer Space Telescope. We collected multiple high-resolution spectra with Very Large Telescope (VLT)/X-shooter to characterise the source star. The event was also observed with VLT Interferometer (VLTI)/PIONIER during the peak. Here we focus on the photometric observations and model the light curve composed of data from Gaia, Spitzer, and multiple optical, ground-based observatories. We find the best-fitting solution with parallax and finite source effects. We derived the limit on the luminosity of the lens based on the blended light model and spectroscopic distance. RESULTS: We compute the mass of the lens to be 1.13 ± 0.03 M_{⊙} and derive its distance to be 5.52_{−0.64}^{+0.35} kpc. The lens is likely a main sequence star, however its true nature has yet to be verified by future high-resolution observations. Our results are consistent with interferometric measurements of the angular Einstein radius, emphasising that interferometry can be a new channel for determining the masses of objects that would otherwise remain undetectable, including stellar-mass black holes

Single-lens mass measurement in the high-magnification microlensing event Gaia19bld located in the Galactic disc

This work was supported from the Polish NCN grants: Preludium No. 2017/25/N/ST9/01253, Harmonia No. 2018/30/M/ST9/00311, MNiSW grant DIR/WK/2018/12, Daina No. 2017/27/L/ST9/03221, and by the Research Council of Lithuania, grant No. S-LL-19-2. The OGLE project has received funding from the NCN grant MAESTRO 2014/14/A/ST9/00121 to AU. We acknowledge the European Commission’s H2020 OPTICON grant No. 730890. YT acknowledges the support of DFG priority program SPP 1992 “Exploring the Diversity of Extrasolar Planets” (WA 1047/11-1). EB and RS gratefully acknowledge support from NASA grant 80NSSC19K0291. Work by AG was supported by JPL grant 1500811. Work by JCY was supported by JPL grant 1571564. SJF thanks Telescope Live for access to their telescope network. NN acknowledges the support of Data Science Research Center, Chiang Mai University. FOE acknowledges the support from the FONDECYT grant nr. 1201223. MK acknowledges the support from the NCN grant No. 2017/27/B/ST9/02727.Context. Microlensing provides a unique opportunity to detect non-luminous objects. In the rare cases that the Einstein radius θE and microlensing parallax πE can be measured, it is possible to determine the mass of the lens. With technological advances in both ground- and space-based observatories, astrometric and interferometric measurements are becoming viable, which can lead to the more routine determination of θE and, if the microlensing parallax is also measured, the mass of the lens.  Aims. We present the photometric analysis of Gaia19bld, a high-magnification (A approximate to 60) microlensing event located in the southern Galactic plane, which exhibited finite source and microlensing parallax effects. Due to a prompt detection by the Gaia satellite and the very high brightness of I = 9.05 mag at the peak, it was possible to collect a complete and unique set of multi-channel follow-up observations, which allowed us to determine all parameters vital for the characterisation of the lens and the source in the microlensing event.  Methods. Gaia19bld was discovered by the Gaia satellite and was subsequently intensively followed up with a network of ground-based observatories and the Spitzer Space Telescope. We collected multiple high-resolution spectra with Very Large Telescope (VLT)/X-shooter to characterise the source star. The event was also observed with VLT Interferometer (VLTI)/PIONIER during the peak. Here we focus on the photometric observations and model the light curve composed of data from Gaia, Spitzer, and multiple optical, ground-based observatories. We find the best-fitting solution with parallax and finite source effects. We derived the limit on the luminosity of the lens based on the blended light model and spectroscopic distance.  Results. We compute the mass of the lens to be 1.13 ± 0.03 M⊙ and derive its distance to be 5.52-0.64+0.35 kpc. The lens is likely a main sequence star, however its true nature has yet to be verified by future high-resolution observations. Our results are consistent with interferometric measurements of the angular Einstein radius, emphasising that interferometry can be a new channel for determining the masses of objects that would otherwise remain undetectable, including stellar-mass black holes.Publisher PDFPeer reviewe

Relativistic Binaries in Globular Clusters

Galactic globular clusters are old, dense star systems typically containing 10\super{4}--10\super{7} stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution that leads to relativistic binaries, and current and possible future observational evidence for this population. Our discussion of globular cluster evolution will focus on the processes that boost the production of hard binary systems and the subsequent interaction of these binaries that can alter the properties of both bodies and can lead to exotic objects. Direct {\it N}-body integrations and Fokker--Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.Comment: 88 pages, 13 figures. Submitted update of Living Reviews articl

Retratos da informalidade: a fragilidade dos sistemas de proteção social em momentos de infortúnio Informality portraits: the fragility of social protectionist systems in misfortune situations

A pesquisa teve como objetivo estudar as estratégias e redes sociais utilizadas por trabalhadores informais em situações de infortúnio. Foram entrevistados dezesseis trabalhadores da construção de edificações de São Carlos (SP). Procuramos entender como esses trabalhadores lidam com a perda da capacidade de trabalho diante do contexto de precariedade e como percebem tais situações. As análises qualitativas apontam que a maior parte dos entrevistados encontra dificuldades financeiras para adquirir formas privadas de proteção. Os resultados mostram que as redes sociais informais são fundamentais no enfrentamento dos períodos de incapacidade laboral, prevalecendo os apoios da família nuclear e extensa e das redes formadas na identificação religiosa.<br>The research has as the objective to study the strategies and social networks used by informal workers in misfortune situations. We interviewed sixteen workers of the buildings' construction sector of São Carlos (São Paulo, Brazil). We tried to understand how they deal with working capacity reduction inside a precariousness context and how they perceive these situations. The qualitative analysis shows that most of them have financial difficulties to acquire private forms of protection. We could infer that informal social networks are essential for them deal to periods of working incapacity. Moreover the nuclear and extended family supports and religious networks are predominating

MOA-2015-BLG-337: A Planetary System with a Low-mass Brown Dwarf/Planetary Boundary Host, or a Brown Dwarf Binary

We report the discovery and the analysis of the short timescale binary-lens microlensing event, MOA-2015-BLG-337. The lens system could be a planetary system with a very low mass host, around the brown dwarf/planetary mass boundary, or a brown dwarf binary. We found two competing models that explain the observed light curves with companion/host mass ratios of q~0.01 and ~0.17, respectively. From the measurement of finite source effects in the best-fit planetary model, we find a relatively small angular Einstein radius of θE ≃ 0.03 mas which favors a low mass lens. We conduct a Bayesian analysis to obtain the probability distribution of the lens properties. The results for the planetary models strongly depend on the minimum mass, M_min, in the assumed mass function. In summary, there are two solutions of the lens system: (1) a brown dwarf/planetary mass boundary object orbited by a super-Neptune (the planetary model with M_min=0.001 M_sun) and (2) a brown dwarf binary (the binary model). If the planetary models is correct, this system can be one of a new class of planetary system, having a low host mass and also a planetary mass ratio (q <0.03) between the host and its companion. The discovery of the event is important for the study of planetary formation in very low mass objects. In addition, it is important to consider all viable solutions in these kinds of ambiguous events in order for the future comprehensive statistical analyses of planetary/binary microlensing events

Apoio social e saúde: pontos de vista das ciências sociais e humanas Social support and health: standpoints from the social and human sciences

Analisam-se os temas e as abordagens teórico-conceituais do apoio social nos artigos de importantes periódicos internacionais de ciências sociais e de medicina e nacionais de Saúde Coletiva/Saúde Pública no período 1983-2005. Procedeu-se a leitura dos resumos dos 259 textos internacionais e 57 nacionais encontrados classificando e computando as relações do apoio social com a saúde/doença/cuidado. A seguir analisaram-se os conceitos e as abordagens do apoio social do ponto de vista das teorias e dos autores das ciências sociais e humanas, em uma amostra intencional de 56 textos internacionais e 18 nacionais. A literatura internacional respalda-se na psicologia social, nas várias correntes da sociologia e da ciência política e menos na antropologia. A literatura nacional dialoga menos com as teorias psicossociais e mais com as sociológicas e as antropológicas, realçando-se pela abordagem do apoio com a rede social, a solidariedade, as trocas e os valores culturais, deslocando-se da esfera individual e privada para a capacidade de organização da sociedade civil e de ações coletivas. Diferentes correntes norteiam as análises teórico-conceituais do apoio social, sendo a literatura internacional mais antiga, diversificada, empírica e escassa de produção antropológica.<br>This article analyses the themes and conceptual-theoretical approaches of the social support in the literature from important international journals about social sciences and medicine, and in from 1983 to 2005 are analyzed. 259 international and 57 national abstracts was reading for the identification and computing the relations of the social support with health/disease/care. A deeper conceptual analysis about social support and the theories of social science were reported in an intentional sample of 56 international and 18 national texts. The international literature is based on the social psychology, in the several trends of the sociology and of the political science and less in the anthropology. The national literature dialogues less with the psychosocial theories and more with the sociological and anthropological theories. In this latter literature the social support approaches are concerned with social network theories; reciprocity, exchanges and cultural values. It is concluded that different trends guide the conceptual-theoretical analyses of the social support, being the international literature older, wider, more diversified and empirical, but with scarce anthropological production. The national literature is more reflexive them empirical

VISTA Variables in the Vía Láctea (VVV): Current Status and First Results

VISTA Variables in the Vía Láctea (VVV) is a public ESO near-IR variability survey aimed at scanning the Milky Way Bulge and an adjacent section of the mid-plane. VVV observations started in October 2009 during ESO science verification. Regular observations for the first year of the survey have been conducted since February 2010 and will cover a total area of 520 square degrees in five passbands and five epochs. Here we address the first results obtained from the VVV Survey as well as the current status of the observations

The VVV Survey of the Milky Way: first year results

The VISTA Variables in the Via Lactea (VVV) is an ESO public near-IR variability survey that is scanning the Milky Way bulge and an adjacent section of the Galactic mid-plane. The survey will take 1929 hours of observations with the VISTA 4.1-m telescope during five years, covering a billion point sources across an area of 520 sqdeg, including 36 known globular clusters and more than 350 open clusters. The final product will be a deep IR atlas in five passbands (0.9 - 2.5 microns) and a catalogue of more than a million variable point sources