321 research outputs found

    Discovery of new globular clusters in the Sagittarius dwarf galaxy

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    © ESO 2021. Published by EDP Sciences. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1051/0004-6361/202140395Context. Globular clusters (GCs) are witnesses of the past accretion events onto the Milky Way. In particular, the GCs of the Sagittarius (Sgr) dwarf galaxy are important probes of an on-going merger. Aims. Our main goal is to search for new GC members of this dwarf galaxy using the VISTA Variables in the Via Lactea Extended Survey (VVVX) near-infrared database combined with the Gaia Early Data Release 3 (EDR3) optical database. Methods. We investigated all VVVX-enabled discoveries of GC candidates in a region covering about 180 sq. deg. toward the bulge and the Sgr dwarf galaxy. We used multiband point-spread function photometry to obtain deep color-magnitude diagrams (CMDs) and luminosity functions (LFs) for all GC candidates, complemented by accurate Gaia-EDR3 proper motions (PMs) to select Sgr members and variability information to select RR Lyrae which are potential GC members. Results. After applying a strict PM cut to discard foreground bulge and disk stars, the CMDs and LFs for some of the GC candidates exhibit well defined red giant branches and red clump giant star peaks. We selected the best Sgr GCs, estimating their distances, reddenings, and associated RR Lyrae. Conclusions. We discover 12 new Sgr GC members, more than doubling the number of GCs known in this dwarf galaxy. In addition, there are 11 other GC candidates identified that are uncertain, awaiting better data for confirmation.Peer reviewedFinal Accepted Versio

    Physics demos for all UVEG degrees: a unique project in Spain

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    The Physics Demo Project at the University of Valencia (www.uv.es/fisicademos) has developed a collection of physics demonstrations to be used during lectures. It consists of more than 130 experimental demos about different physics topics. More than 30 professors borrow them whenever they lecture on physics in any of our 40 courses in 17 different science or technical degrees, involving 246 ECTS and more than 3500 students. Each demo kit with a simple experimental set displays a particular physics phenomenon. An on-line user guide highlights the main physics principles involved, instructions on how to use it and advices of how to link it to the theoretical concepts or to technical applications. Demo lectures (and collections) are a usual and widespread practice in many countries but not in Spain. This unique initiative aims at the recovery of this practice by involving a growing collaborative team of users and with the aid of educational innovation projects. Here we explain the project content, organization and recent developments. Our experience, together with the positive students comments, allows us to draw the following conclusions: demos introduce the real sensible world in the lecture hall, providing the necessary link between concepts and everyday life, and becoming, again, something more than "chalk and talk"

    Resonant Rayleigh scattering of exciton-polaritons in multiple quantum wells

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    A theoretical concept of resonant Rayleigh scattering (RRS) of exciton-polaritons in multiple quantum wells (QWs) is presented. The optical coupling between excitons in different QWs can strongly affect the RRS dynamics, giving rise to characteristic temporal oscillations on a picosecond scale. Bragg and anti-Bragg arranged QW structures with the same excitonic parameters are predicted to have drastically different RRS spectra. Experimental data on the RRS from multiple QWs show the predicted strong temporal oscillations at small scattering angles, which are well explained by the presented theory

    VVVX-Gaia Discovery of a Low Luminosity Globular Cluster in the Milky Way Disk

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    © 2020 ESOMilky Way globular clusters (MW GCs) are difficult to identify at low Galactic latitudes because of high differential extinction and heavy star crowding. The new deep near-IR images and photometry from the VISTA Variables in the Via L\'actea Extended Survey (VVVX) allow us to chart previously unexplored regions. Our long term aim is to complete the census of MW GCs. The immediate goals are to estimate the astrophysical parameters, measuring their reddenings, extinctions, distances, total luminosities, proper motions, sizes, metallicities and ages. We use the near-IR VVVX survey database, in combination with Gaia DR2 optical photometry, and with the Two Micron All Sky Survey (2MASS) photometry. We report the detection of a heretofore unknown Galactic Globular Cluster at RA = 14:09:00.0; DEC=-65:37:12 (J2000). We calculate a reddening of E(J-K_s)=(0.3 +/- 0.03) mag and an extinction of A_Ks=(0.15 +/- 0.01) mag for this new GC. Its distance modulus and corresponding distance were measured as (m-M)=(15.93 +/- 0.03) mag and D=(15.5 +/- 1.0) kpc, respectively. We estimate the metallicity and age by comparison with known GCs and by fitting PARSEC and Dartmouth isochrones, finding [Fe/H]=(0.70±0.2)[Fe/H]=(-0.70\pm0.2) dex and t=(11.0 +/- 1.0) Gyr. The mean GC PMs from Gaia are mu_alpha^(star)=(-4.68 +/- 0.47) mas yr^(-1) and mu_delta=(-1.34 \pm 0.45) mas yr^(-1). The total luminosity of our cluster is estimated to be M_Ks=(-7.76 +/- 0.5) mag. We have found a new low-luminosity, old and metal-rich globular cluster, situated in the far side of the Galactic disk, at R_G=11.2 kpc from the Galactic centre, and at z=1.0 kpc below the plane. Interestingly, the location, metallicity and age of this globular cluster are coincident with the Monoceros Ring (MRi) structure.Peer reviewe

    An ethical exploration of the narratives surrounding substance use and pain management at the end of life: a discussion paper.

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    This discussion article examines narrative positioning related to pain management for people who use substances at the end of life. We explore how dominant narrative genres associated with biomedicine, such as 'restitution' and narratives common within the context of drug services such as 'recovery' can hinder effective pain management within this population. We argue that these discourses can marginalise the ethical self-identity of patients who use substances at the end of life. It can also trouble health and social care professionals in supporting patients and generating counter-narratives that challenge those often associated with substance use. Stigma is a common experience for this population with stereotyping as 'junkies' and associated with criminality. They are positioned as drug-seeking, and this requires more surveillance at the end of life when opioid therapy is potentially more available and authorised. This can make it challenging to generate 'companion' stories that are positive and maintain moral adequacy. Dominant biomedical narrative genres often prevent the recognition of the fractured stories that people using substances can often present with. This can lead to narrative silencing and to the under treatment of pain. The person's self-identity is invested in narratives of recovery, and opioid use symbolises their addicted past because for practitioners, this population is at clinical risk with the potential for drug seeking behaviours. Whilst not requiring formal ethical review this discussion paper was constructed in accordance with good scientific practice with the work of other researchers respected and cited appropriately
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