We present a new self-consistent and versatile method that derives photo-spheric radius and temperature variations of Type II-Plateau supernovae based on their expansion velocities and photo-metric ...measurements. We apply the method to a sample of 26 well-observed, nearby supernovae with published light curves and velocities. We simultaneously fit ~230 velocity and ~6800 mag measurements distributed over 21 photometric pass-bands spanning wavelengths from 0.19 to 2.2 mu m. We compare our model to the theoretical dilution factors and find good agreement for the B and V filters. Our results differ from the theory when the I, J, H, or K bands are included. We investigate the reddening law toward our supernovae and find reasonable agreement with standard RV ~ 3.1 reddening law in UBVRI bands. Results for other bands are inconclusive. We make our fitting code publicly available.
ABSTRACT Hydrogen-rich Type II-Plateau supernovae (SNe) exhibit correlations between the plateau luminosity , the nickel mass , the explosion energy , and the ejecta mass . Using our global, ...self-consistent, multi-band model of nearby well-observed SNe, we find that the covariances of these quantities are strong and that the confidence ellipsoids are oriented in the direction of the correlations, which reduces their significance. By proper treatment of the covariance matrix of the model, we discover a significant intrinsic width to the correlations between , and , where the uncertainties due to the distance and the extinction dominate. For fixed , the spread in is about 0.25 dex, which we attribute to the differences in the progenitor internal structure. We argue that the effects of incomplete γ-ray trapping are not important in our sample. Similarly, the physics of the Type II-Plateau SN light curves leads to inherently degenerate estimates of and , which makes their observed correlation weak. Ignoring the covariances of SN parameters or the intrinsic width of the correlations causes significant biases in the slopes of the fitted relations. Our results imply that Type II-Plateau SN explosions are not described by a single physical parameter or a simple one-dimensional trajectory through the parameter space, but instead reflect the diversity of the core and surface properties of their progenitors. We discuss the implications for the physics of the explosion mechanism and possible future observational constraints.
The recent supernova (SN) known as SN 2009ip had dramatic precursor eruptions followed by an even brighter explosion in 2012. Its pre-2012 observations make it the best documented SN progenitor in ...history, but have fuelled debate about the nature of its 2012 explosion – whether it was a true SN or some type of violent non-terminal event. Both could power shock interaction with circumstellar material (CSM), but only a core-collapse SN provides a self-consistent explanation. The persistent broad emission lines in the spectrum require a relatively large ejecta mass, and a corresponding kinetic energy of at least 1051 erg, while the faint 2012a event is consistent with published models of core-collapse SNe from compact (∼60 R⊙) blue supergiants. The light curves of SN 2009ip and another Type IIn, SN 2010mc, were nearly identical; we demonstrate that their spectra match as well, and that both are standard SNe IIn. Our observations contradict the recent claim that the late-time spectrum of SN 2009ip is returning to its progenitor's luminous blue variable-like state, and we show the that late-time spectra of SN 2009ip closely resemble the spectra of SN 1987A. Moreover, SN 2009ip's changing Hα equivalent width after explosion matches behaviour typically seen in core-collapse SNe IIn. Several key facts about SN 2009ip and SN 2010mc argue strongly in favour of a core-collapse interpretation, and make a non-terminal 1050 erg event implausible. The most straightforward and self-consistent interpretation is that SN 2009ip was an initially faint core-collapse explosion of a blue supergiant that produced about half as much 56Ni as SN 1987A, with most of the peak luminosity from CSM interaction.
The single-degenerate scenario for Type Ia supernovae should yield metal-rich ejecta that enclose some stripped material from the non-degenerate H-rich companion star. We present a large grid of ...non-local thermodynamic equilibrium steady-state radiative transfer calculations for such hybrid ejecta and provide analytical fits for the H
α
luminosity and equivalent width. Our set of models covers a range of masses for
56
Ni and the ejecta, for the stripped material (
M
st
), and post-explosion epochs from 100 to 300 d. The brightness contrast between stripped material and metal-rich ejecta challenges the detection of H
I
and He
I
lines prior to ~100 d. Intrinsic and extrinsic optical depth effects also influence the radiation emanating from the stripped material. This inner denser region is marginally thick in the continuum and optically thick in all Balmer lines. The overlying metal-rich ejecta blanket the inner regions, completely below about 5000 Å, and more sparsely at longer wavelengths. As a consequence, H
β
should not be observed for all values of
M
st
up to at least 300 days, while H
α
should be observed after ~100 d for all
M
st
≥ 0.01
M
⊙
. Observational non-detections capable of limiting the H
α
equivalent width to <1 Å set a formal upper limit of
M
st
< 0.001
M
⊙
. This contrasts with the case of circumstellar-material (CSM) interaction, not subject to external blanketing, which should produce H
α
and H
β
lines with a strength dependent primarily on CSM density. We confirm previous analyses that suggest low values of order 0.001
M
⊙
for
M
st
to explain the observations of the two Type Ia supernovae with nebular-phase H
α
detection, in conflict with the much greater stripped mass predicted by hydrodynamical simulations for the single-degenerate scenario. A more likely solution is the double-degenerate scenario, together with CSM interaction, or enclosed material from a tertiary star in a triple system or from a giant planet.
Background & Aims Tremelimumab is a monoclonal antibody that blocks cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), an inhibitory co-receptor that interferes with T cell activation and ...proliferation. The purpose of this pilot clinical trial was to test the antitumor and antiviral effect of tremelimumab in patients with hepatocellular carcinoma (HCC) and chronic hepatitis C virus (HCV) infection; and to study the safety of its administration to cirrhotic patients. Methods Tremelimumab at a dose of 15 mg/kg IV every 90 days was administered until tumor progression or severe toxicity. Twenty patients were assessable for toxicity and viral response and 17 were assessable for tumor response. Most patients were in the advanced stage and 43% had an altered liver function (Child-Pugh class B). Results A good safety profile was recorded and no patient needed steroids because of severe immune-mediated adverse events. Some patients had a transient albeit intense elevation of transaminases after the first dose, but not following subsequent cycles. Partial response rate was 17.6% and disease control rate was 76.4%. Time to progression was 6.48 months (95% CI 3.95–9.14). A significant drop in viral load was observed while new emerging variants of the hypervariable region 1 of HCV replaced the predominant variants present before therapy, particularly in those patients with a more prominent drop in viral load. This antiviral effect was associated with an enhanced specific anti-HCV immune response. Conclusions Tremelimumab safety profile and antitumor and antiviral activity, in patients with advanced HCC developed on HCV-induced liver cirrhosis, support further investigation.
Context.
The peculiar supernova (SN) 2009ip was an ambiguous event that placed many questions on its true origin. Here, we present very late-time spectroscopic and photometric observations of SN ...2009ip, obtained 9 years (3274 days) after the 2012B outburst.
Aims.
We analyze the H
α
emission still present in the very late-time spectrum of SN 2009ip. We also obtain photometric measurements in
r
,
g
and
i
bands.
Methods.
We obtain observations of SN 2009ip on 2021 September 10 with the IMACS instrument at the 6.5 m
Magellan Baade
Telescope, located at the Las Campanas Observatory.
Results.
SN 2009ip was detected in
r
,
g
and
i
bands, with an absolute magnitude in
r
band of ∼ − 8.66 mag. We show that the source faded significantly since the last observations in these bands. We further show that the very late-time spectrum contains a persistent H
α
emission, although no other emission lines were detected. We measure a full width at half maximum of 930 ± 40 km s
−1
and luminosity of ∼ 8.0 × 10
37
erg s
−1
for the H
α
emission. The luminosity decreased relatively slowly in comparison to the last observations and its fading rate is very similar to other long-living interacting transients, such as SN 2005ip. Finally, we conclude that although these properties could be consistent with a non-regular core-collapse SN, they could also be explained by non-terminal explosion scenarios.
We discover clear doubly peaked line profiles in 3 out of ∼20 Type Ia supernovae (SNe Ia) with high-quality nebular-phase spectra. The profiles are consistently present in three separated Co/Fe ...emission features. The two peaks are respectively blueshifted and redshifted relative to the host galaxies and are separated by ∼5000 km s−1. The doubly peaked profiles directly reflect a bimodal velocity distribution of the radioactive 56Ni in the ejecta that powers the emission of these SNe. Due to their random orientations, only a fraction of SNe with intrinsically bimodal velocity distributions will appear as doubly peaked spectra. Therefore, SNe with intrinsic bimodality are likely common, especially among the SNe in the low-luminosity part on the Phillips relation (Δm
15(B) ≳ 1.3; ∼ 40 per cent of all SNe Ia). Such bimodality is naturally expected from direct collisions of white dwarfs (WDs) due to the detonation of both WDs and is demonstrated in a 3D 0.64–0.64M⊙ WD collision simulation. In the future, with a large sample of nebular spectra and a comprehensive set of numerical simulations, the collision model can be unambiguously tested as the primary channel for SNe Ia, and the distribution of nebular line profiles will either be a smoking gun or rule it out.
We test the hypothesis that metal-poor globular clusters form within disk galaxies at redshifts image. We calculate the orbits of model clusters in the time-variable gravitational potential of a ...Milky Way-sized galaxy, using the outputs of a cosmological N-body simulation. We find that at present the orbits are isotropic in the inner 50 kpc of the Galaxy and preferentially radial at larger distances. All clusters located outside 10 kpc from the center formed in satellite galaxies, some of which are now tidally disrupted and some of which survive as dwarf galaxies. Mergers of the progenitors lead to a spheroidal spatial distribution of model clusters, although it is more extended than that of Galactic metal-poor clusters and has a somewhat shallower power-law slope of the number density profile, image. The combination of two-body relaxation, tidal shocks, and stellar evolution drives the evolution of the cluster mass function from an initial power law to a peaked distribution, in agreement with observations. However, not all initial conditions and not all evolution scenarios are consistent with the observed mass function of the Galactic globular clusters. We find that our best-fitting models require the average cluster density, image, to be constant initially for clusters of all mass and to remain constant with time. However, these models do not explain the observed decrease of the mean density with galactocentric distance. Both synchronous formation of all clusters at a single epoch and continuous formation over a span of 1.6 Gyr (between image and 3) are consistent with the data. For both formation scenarios, we provide online catalogs of the main physical properties of model clusters.
We present the discovery and early evolution of ASASSN-19bt, a tidal disruption event (TDE) discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN) at a distance of d 115 Mpc and the ...first TDE to be detected by TESS. As the TDE is located in the TESS Continuous Viewing Zone, our data set includes 30 minute cadence observations starting on 2018 July 25, and we precisely measure that the TDE begins to brighten ∼8.3 days before its discovery. Our data set also includes 18 epochs of Swift UVOT and XRT observations, 2 epochs of XMM-Newton observations, 13 spectroscopic observations, and ground data from the Las Cumbres Observatory telescope network, spanning from 32 days before peak through 37 days after peak. ASASSN-19bt thus has the most detailed pre-peak data set for any TDE. The TESS light curve indicates that the transient began to brighten on 2019 January 21.6 and that for the first 15 days, its rise was consistent with a flux ∝t2 power-law model. The optical/UV emission is well fit by a blackbody spectral energy distribution, and ASASSN-19bt exhibits an early spike in its luminosity and temperature roughly 32 rest-frame days before peak and spanning up to 14 days, which has not been seen in other TDEs, possibly because UV observations were not triggered early enough to detect it. It peaked on 2019 March 4.9 at a luminosity of L 1.3 × 1044 erg s−1 and radiated E 3.2 × 1050 erg during the 41 day rise to peak. X-ray observations after peak indicate a softening of the hard X-ray emission prior to peak, reminiscent of the hard/soft states in X-ray binaries.
Research efforts in neurorehabilitation technologies have been directed towards creating robotic exoskeletons to restore motor function in impaired individuals. However, despite advances in ...mechatronics and bioelectrical signal processing, current robotic exoskeletons have had only modest clinical impact. A major limitation is the inability to enable exoskeleton voluntary control in neurologically impaired individuals. This hinders the possibility of optimally inducing the activity-driven neuroplastic changes that are required for recovery.
We have developed a patient-specific computational model of the human musculoskeletal system controlled via neural surrogates, i.e., electromyography-derived neural activations to muscles. The electromyography-driven musculoskeletal model was synthesized into a human-machine interface (HMI) that enabled poststroke and incomplete spinal cord injury patients to voluntarily control multiple joints in a multifunctional robotic exoskeleton in real time.
We demonstrated patients' control accuracy across a wide range of lower-extremity motor tasks. Remarkably, an increased level of exoskeleton assistance always resulted in a reduction in both amplitude and variability in muscle activations as well as in the mechanical moments required to perform a motor task. Since small discrepancies in onset time between human limb movement and that of the parallel exoskeleton would potentially increase human neuromuscular effort, these results demonstrate that the developed HMI precisely synchronizes the device actuation with residual voluntary muscle contraction capacity in neurologically impaired patients.
Continuous voluntary control of robotic exoskeletons (i.e. event-free and task-independent) has never been demonstrated before in populations with paretic and spastic-like muscle activity, such as those investigated in this study. Our proposed methodology may open new avenues for harnessing residual neuromuscular function in neurologically impaired individuals via symbiotic wearable robots.
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