74 research outputs found

    ASASSN-16ae: A Powerful White-Light Flare on an Early-L Dwarf

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    We report the discovery and classification of SDSS~J053341.43+001434.1 (SDSS0533), an early-L dwarf first discovered during a powerful ΔV<−11\Delta V < -11 magnitude flare observed as part of the ASAS-SN survey. Optical and infrared spectroscopy indicate a spectral type of L0 with strong Hα\alpha emission and a blue NIR spectral slope. Combining the photometric distance, proper motion, and radial velocity of SDSS0533 yields three-dimensional velocities of (U,V,W)=(14±13,−35±14,−94±22)(U,V,W)=(14\pm13,-35\pm14,-94\pm22)~km~s−1^{-1}, indicating that it is most likely part of the thick disk population and probably old. The three detections of SDSS0533 obtained during the flare are consistent with a total VV-band flare energy of at least 4.9×10334.9\times10^{33}~ergs (corresponding to a total thermal energy of at least Etot>3.7×1034E_{\rm tot}>3.7\times10^{34}~erg), placing it among the strongest detected M dwarf flares. The presence of this powerful flare on an old L0 dwarf may indicate that stellar-type magnetic activity persists down to the end of the main sequence and on older ML transition dwarfs.Comment: 7 pages, 3 tables, 2 figures; accepted to ApJ Letters; updated to reflect referee response and proof correction

    Largest M Dwarf Flares from ASAS-SN

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    The All-sky Automated Survey for Supernovae (ASAS-SN) is the only project in existence to scan the entire sky in optical light approximately every day, reaching a depth of g ~ 18 mag. Over the course of its first 4 yr of transient alerts (2013–2016), ASAS-SN observed 53 events classified as likely M dwarf flares. We present follow-up photometry and spectroscopy of all 53 candidates, confirming flare events on 47 M dwarfs, one K dwarf, and one L dwarf. The remaining four objects include a previously identified T Tauri star, a young star with outbursts, and two objects too faint to confirm. A detailed examination of the 49 flare star light curves revealed an additional six flares on five stars, resulting in a total of 55 flares on 49 objects ranging in V-band contrast from ΔV = −1 to −10.2 mag. Using an empirical flare model to estimate the unobserved portions of the flare light curve, we obtain lower limits on the V-band energy emitted during each flare, spanning log(E_V/erg) = 32–35, which are among the most energetic flares detected on M dwarfs. The ASAS-SN M dwarf flare stars show a higher fraction of Hα emission, as well as stronger Hα emission, compared to M dwarfs selected without reference to activity, consistent with belonging to a population of more magnetically active stars. We also examined the distribution of tangential velocities, finding that the ASAS-SN flaring M dwarfs are likely to be members of the thin disk and are neither particularly young nor old

    The detection of M-dwarf UV flare events in the GALEX data archives

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    We present the preliminary results from implementing a new software tool that enables inspection of time-tagged photon data for the astronomical sources contained within individual GALEX ultraviolet images of the sky. We have inspected the photon data contained within 1802 GALEX images to reveal rapid, short-term (<500 sec) UV source variability in the form of stellar flares. The mean associated change in NUV magnitude due to this flaring activity is 2.7+/-0.3 mag. A list of 49 new UV variable-star candidates is presented, together with their associated Sloan Digital Sky Survey (SDSS) photometric magnitudes. From these data we can associate the main source of these UV flare events with magnetic activity on M-dwarf stars. Photometric parallaxes have been determined for 32 of these sources, placing them at distances ranging from approximately 25 to 1000pc. The average UV flare energy for these flare events is 2.5E30 ergs, which is of a similar energy to that of U-band, X-ray and EUV flares observed on many local M-dwarf stars. We have found that stars of classes M0 to M5 flare with energies spanning a far larger range and with an energy approximately 5 times greater than those of later (M6 to M8) spectral type.Comment: Accepted for the Astrophysical Journal Supplement, GALEX Special Issu

    Prostate-Specific Antigen Screening and 15-year Prostate Cancer Mortality:A Secondary Analysis of the CAP Randomized Clinical Trial

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    Key PointsQuestion  In men aged 50 to 69 years, does a single invitation for a prostate-specific antigen (PSA) screening test reduce prostate cancer mortality at 15-year follow-up compared with no invitation for testing?Findings  In this secondary analysis of a randomized clinical trial of 415 357 men aged 50 to 69 years randomized to a single invitation for PSA screening (n = 195 912) or a control group without PSA screening (n = 219 445) and followed up for a median of 15 years, risk of death from prostate cancer was lower in the group invited to screening (0.69% vs 0.78%; mean difference, 0.09%) compared with the control group.Meaning  Compared with no invitation for routine PSA testing, a single invitation for a PSA screening test reduced prostate cancer mortality at a median follow-up of 15 years, but the absolute mortality benefit was small.AbstractIMPORTANCE The Cluster randomized trial of PSA testing for Prostate cancer (CAP) reported no effect of prostate specific antigen (PSA) screening on prostate cancer mortality at median 10-year follow-up (primary outcome), but the long-term effects of PSA screening on prostate cancer mortality remain unclear.OBJECTIVE To evaluate the effect of a single invitation for PSA screening on the pre-specified secondary outcome of prostate cancer-specific mortality at a median of 15 years’ follow-up, compared to a control group not invited for screening. DESIGN, SETTING, PARTICIPANTS Cluster randomized trial of men aged 50-69 identified from 573 primary-care practices in England and Wales. Primary-care practices were randomized between 09/25/2001 and 08/24/2007 and men were enrolled between 01/08/2002 and 01/20/2009. Follow-up was completed on 03/31/2021. INTERVENTION A single invitation for a PSA screening test with subsequent diagnostic tests if PSA≥3.0ng/ml, compared to standard practice (control). MAIN OUTCOMES AND MEASURES The primary outcome was reported previously. Of eight prespecified secondary outcomes, results of four were reported previously. The four remaining pre-specified secondary outcomes at 15-year follow-up were prostate cancer-specific mortality, all-cause mortality, and prostate cancer stage and Gleason grade at diagnosis.RESULTS Of 415,357 randomized men (mean [SD] age: 59.0 [5.6] years), 98% were analyzed in these analyses. Overall, 12,013 and 12,958 men with prostate cancers were diagnosed in the intervention and control groups (15-year cumulative risks 7.1% and 6.9% respectively). At a median 15-year follow-up, 1,199 (0.69%) men in the intervention group and 1,451 (0.78%) men in the control group died of prostate cancer (rate ratio [RR] 0.92 [95% CI 0.85, 0.99]; p=0.03). Compared to the control group, the PSA screening intervention increased detection of low-grade (Gleason score [GS]≤6; 2.2% versus 1.6%;p&lt;0.001) and localized (T1/T2; 3.6% versus 3.1%;p&lt;0.001) disease, but not intermediate (GS=7), high-grade (GS≥8), locally-advanced (T3) or distally-advanced (T4/N1/M1) tumors. There were 45,084 all-cause deaths (23.2%) in the intervention group and 50,336 deaths (23.3%) in the control group respectively (RR 0.97 [95% CI 0.94, 1.01]; p=0.11). Eight deaths in the intervention and seven deaths in the control group were related to a diagnostic biopsy or prostate cancer treatment.CONCLUSIONS AND RELEVANCE A single invitation for PSA screening, compared to standard practice without routine screening, reduced the secondary outcome of prostate cancer deaths at a median follow-up of 15-years. However, the absolute reduction in deaths was small.<br/

    A turbulent wake as a tracer of 30,000 years of Mira’s mass loss history

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    Mira is one of the first variable stars ever discovered and it is the prototype (and also the nearest example) of a class of low-to-intermediate-mass stars in the late stages of stellar evolution. These stars are relatively common and they return a large fraction of their original mass to the interstellar medium (ISM) (ref. 2) through a processed, dusty, molecular wind. Thus stars in Mira's stage of evolution have a direct impact on subsequent star and planet formation in their host galaxy. Previously, the only direct observation of the interaction between Mira-type stellar winds and the ISM was in the infrared. Here we report the discovery of an ultraviolet-emitting bow shock and turbulent wake extending over 2 degrees on the sky, arising from Mira's large space velocity and the interaction between its wind and the ISM. The wake is visible only in the far ultraviolet and is consistent with an unusual emission mechanism whereby molecular hydrogen is excited by turbulent mixing of cool molecular gas and shock-heated gas. This wind wake is a tracer of the past 30,000 years of Mira's mass-loss history and provides an excellent laboratory for studying turbulent stellar wind–ISM interactions

    ARMAZENAGEM REFRIGERADA DE PIMENTAS SOB CONDIÇÃO DE ATMOSFERA NORMAL E MODIFICADA

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    O cultivo de pimentas pode ser mais uma opção para os produtores diversificarem a produção e aumentarem sua renda. com este objetivo desenvolve-se pesquisas sobre o comportamento e adaptação das cultivares ‘Malagueta’, ‘Chapéu de Bispo’, ‘Cheiro de Luna’, ‘Jalapeño’ e ‘Novo México’ hà região e sua conservação armazenadas em frio em atmosfera normal e atmosfera modificada. O resultado esperado para este trabalho é o de a armazenagem em atmosfera modificada conservar o fruto por mais tempo em relação a armazenagem em atmosfera normal preservando as pimentas

    The Galex Ultraviolet Variability (GUVV) Catalog

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    We present Version 1.0 of the NASA Galaxy Evolution Explorer (GALEX) ultraviolet variability catalog (GUVV) that contains information on 84 time-variable and transient sources gained with simultaneous near and far ultraviolet photometric observations. These time-variable sources were serendipitously revealed in the various 1.2 degree star fields currently being surveyed by the GALEX satellite in two ultraviolet bands (NUV 1750-2750A, FUV 1350-1750A) with limiting AB magnitudes of 23-25. The largest-amplitude variable objects presently detected by GALEX are M-dwarf flare stars, which can brighten by 5-10 mag in both the NUV and FUV bands during short duration (< 500s) outbursts. Other types of large-amplitude ultraviolet variable objects include ab-type RR Lyrae stars, which can vary periodically by 2-5mag in the GALEX FUV band. This first GUVV catalog lists galactic positions and possible source identifications in order to provide the astronomical community with a list of time-variable objects that can now be repeatedly observed at other wavelengths. We expect the total number of time-variable source detections to increase as the GALEX mission progresses, such that later version numbers of the GUVV catalog will contain substantially more variable sources

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure
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