74 research outputs found
ASASSN-16ae: A Powerful White-Light Flare on an Early-L Dwarf
We report the discovery and classification of SDSS~J053341.43+001434.1
(SDSS0533), an early-L dwarf first discovered during a powerful magnitude flare observed as part of the ASAS-SN survey. Optical and
infrared spectroscopy indicate a spectral type of L0 with strong H
emission and a blue NIR spectral slope. Combining the photometric distance,
proper motion, and radial velocity of SDSS0533 yields three-dimensional
velocities of ~km~s, 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 -band flare energy of at least ~ergs (corresponding
to a total thermal energy of at least ~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
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
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
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<0.001) and localized (T1/T2; 3.6% versus 3.1%;p<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
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
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
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
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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