The brightness of type Ia supernovae, and their homogeneity as a class, makes them powerful tools in cosmology, yet little is known about the progenitor systems of these explosions. They are thought ...to arise when a white dwarf accretes matter from a companion star, is compressed and undergoes a thermonuclear explosion. Unless the companion star is another white dwarf (in which case it should be destroyed by the mass-transfer process itself), it should survive and show distinguishing properties. Tycho's supernova is one of only two type Ia supernovae observed in our Galaxy, and so provides an opportunity to address observationally the identification of the surviving companion. Here we report a survey of the central region of its remnant, around the position of the explosion, which excludes red giants as the mass donor of the exploding white dwarf. We found a type G0-G2 star, similar to our Sun in surface temperature and luminosity (but lower surface gravity), moving at more than three times the mean velocity of the stars at that distance, which appears to be the surviving companion of the supernova.
Prior radiation therapy to the chest, in theory, has a detrimental impact on the recipient vessels in breast reconstruction and may impact microvascular success. The purpose of this study was to ...determine whether prereconstruction radiation therapy affects the rate of vascular complications in free flap breast reconstruction.
This was a retrospective review of free flap breast reconstruction performed between 2005 and 2009 by the senior authors. In addition to medical and surgical history, vascular complications were recorded, including intraoperative and postoperative thromboses and technical difficulties resulting in a variation of the standard approach.
In total, 226 flaps were placed into an irradiated field, whereas 799 were transposed into a radiation-naive defect. Vascular complications as a whole were more prevalent in the irradiated group (9.6 percent versus 17.3 percent; p = 0.001). In regression modeling, radiation therapy was identified as an independent risk factor (odds ratio, 1.68; 95 percent confidence interval, 1.04 to 2.70). In subanalysis, there is a significantly higher rate of intraoperative vascular complications (7.6 percent versus 14.2 percent; p = 0.003), although individual outcomes did not reach formal significance. Previous irradiation had no effect on delayed vascular complications, flap loss, fat necrosis, infection, skin flap necrosis, hematoma, seroma, or delayed wound healing.
Prereconstruction radiation therapy increases the rate of vascular complications in free flap breast reconstruction, the majority of which appear intraoperatively. Although radiation does not hinder the overall success of reconstruction or contribute to postoperative complications, surgeons should be aware that working in a previously irradiated field carries additional technical risk.
We present observations of the Type Ic supernova (SN Ic) 2011bm spanning a period of about one year. The data establish that SN 2011bm is a spectroscopically normal SN Ic with moderately low ejecta ...velocities and with a very slow spectroscopic and photometric evolution (more than twice as slow as SN 1998bw). The Pan-STARRS1 retrospective detection shows that the rise time from explosion to peak was ~40 days in the R band. Through an analysis of the light curve and the spectral sequence, we estimate a kinetic energy of ~7-17 foe and a total ejected mass of ~7-17 M sub(middot in circle), 5-10 M sub(middot in circle) of which is oxygen and 0.6-0.7 M sub(middot in circle) is super(56)Ni. The physical parameters obtained for SN 2011bm suggest that its progenitor was a massive star of initial mass 30-50 M sub(middot in circle). The profile of the forbidden oxygen lines in the nebular spectra shows no evidence of a bi-polar geometry in the ejected material.
When a cardiac arrest occurs, cardiopulmonary resuscitation should be started immediately. However, there is limited evidence about the best approach to airway management during cardiac arrest.
The ...objective was to determine whether or not the i-gel
(Intersurgical Ltd, Wokingham, UK) supraglottic airway is superior to tracheal intubation as the initial advanced airway management strategy in adults with non-traumatic out-of-hospital cardiac arrest.
This was a pragmatic, open, parallel, two-group, multicentre, cluster randomised controlled trial. A cost-effectiveness analysis accompanied the trial.
The setting was four ambulance services in England.
Patients aged ≥ 18 years who had a non-traumatic out-of-hospital cardiac arrest and were attended by a participating paramedic were enrolled automatically under a waiver of consent between June 2015 and August 2017. Follow-up ended in February 2018.
Paramedics were randomised 1 : 1 to use tracheal intubation (764 paramedics) or i-gel (759 paramedics) for their initial advanced airway management and were unblinded.
The primary outcome was modified Rankin Scale score at hospital discharge or 30 days after out-of-hospital cardiac arrest, whichever occurred earlier, collected by assessors blinded to allocation. The modified Rankin Scale, a measure of neurological disability, was dichotomised: a score of 0-3 (good outcome) or 4-6 (poor outcome/death). The primary outcome for the economic evaluation was quality-adjusted life-years, estimated using the EuroQol-5 Dimensions, five-level version.
A total of 9296 patients (supraglottic airway group, 4886; tracheal intubation group, 4410) were enrolled median age 73 years; 3373 (36.3%) women; modified Rankin Scale score was known for 9289 patients. Characteristics were similar between groups. A total of 6.4% (311/4882) of patients in the supraglottic airway group and 6.8% (300/4407) of patients in the tracheal intubation group had a good outcome (adjusted difference in proportions of patients experiencing a good outcome: -0.6%, 95% confidence interval -1.6% to 0.4%). The supraglottic airway group had a higher initial ventilation success rate than the tracheal intubation group 87.4% (4255/4868) vs. 79.0% (3473/4397), respectively; adjusted difference in proportions of patients: 8.3%, 95% confidence interval 6.3% to 10.2%; however, patients in the tracheal intubation group were less likely to receive advanced airway management than patients in the supraglottic airway group 77.6% (3419/4404) vs. 85.2% (4161/4883), respectively. Regurgitation rate was similar between the groups supraglottic airway group, 26.1% (1268/4865); tracheal intubation group, 24.5% (1072/4372); adjusted difference in proportions of patients: 1.4%, 95% confidence interval -0.6% to 3.4%, as was aspiration rate supraglottic airway group, 15.1% (729/4824); tracheal intubation group, 14.9% (647/4337); adjusted difference in proportions of patients: 0.1%, 95% confidence interval -1.5% to 1.8%. The longer-term outcomes were also similar between the groups (modified Rankin Scale: at 3 months, odds ratio 0.89, 95% confidence interval 0.69 to 1.14; at 6 months, odds ratio 0.91, 95% confidence interval 0.71 to 1.16). Sensitivity analyses did not alter the overall findings. There were no unexpected serious adverse events. Mean quality-adjusted life-years to 6 months were 0.03 in both groups (supraglottic airway group minus tracheal intubation group difference -0.0015, 95% confidence interval -0.0059 to 0.0028), and total costs were £157 (95% confidence interval -£270 to £583) lower in the tracheal intubation group. Although the point estimate of the incremental cost-effectiveness ratio suggested that tracheal intubation may be cost-effective, the huge uncertainty around this result indicates no evidence of a difference between groups.
Limitations included imbalance in the number of patients in each group, caused by unequal distribution of high-enrolling paramedics; crossover between groups; and the fact that participating paramedics, who were volunteers, might not be representative of all paramedics in the UK. Findings may not be applicable to other countries.
Among patients with out-of-hospital cardiac arrest, randomisation to the supraglottic airway group compared with the tracheal intubation group did not result in a difference in outcome at 30 days. There were no notable differences in costs, outcomes and overall cost-effectiveness between the groups.
Future work could compare alternative supraglottic airway types with tracheal intubation; include a randomised trial of bag mask ventilation versus supraglottic airways; and involve other patient populations, including children, people with trauma and people in hospital.
This trial is registered as ISRCTN08256118.
This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and supported by the NIHR Comprehensive Research Networks and will be published in full in
; Vol. 26, No. 21. See the NIHR Journals Library website for further project information.
Abstract
Large modern surveys require efficient review of data in order to find transient sources such as supernovae, and to distinguish such sources from artefacts and noise. Much effort has been ...put into the development of automatic algorithms, but surveys still rely on human review of targets. This paper presents an integrated system for the identification of supernovae in data from Pan-STARRS1, combining classifications from volunteers participating in a citizen science project with those from a convolutional neural network. The unique aspect of this work is the deployment, in combination, of both human and machine classifications for near real-time discovery in an astronomical project. We show that the combination of the two methods outperforms either one used individually. This result has important implications for the future development of transient searches, especially in the era of Large Synoptic Survey Telescope and other large-throughput surveys.
ABSTRACT
We present early-time (t < +50 d) observations of SN 2019muj (=ASASSN-19tr), one of the best-observed members of the peculiar SN Iax class. Ultraviolet and optical photometric and optical ...and near-infrared spectroscopic follow-up started from ∼5 d before maximum light tmax(B) on $58707.8$ MJD and covers the photospheric phase. The early observations allow us to estimate the physical properties of the ejecta and characterize the possible divergence from a uniform chemical abundance structure. The estimated bolometric light-curve peaks at 1.05 × 1042 erg s−1 and indicates that only 0.031 M⊙ of 56Ni was produced, making SN 2019muj a moderate luminosity object in the Iax class with peak absolute magnitude of $M_\rm {V} = -16.4$ mag. The estimated date of explosion is t0 = $58698.2$ MJD and implies a short rise time of trise = 9.6 d in B band. We fit of the spectroscopic data by synthetic spectra, calculated via the radiative transfer code tardis. Adopting the partially stratified abundance template based on brighter SNe Iax provides a good match with SN 2019muj. However, without earlier spectra, the need for stratification cannot be stated in most of the elements, except carbon, which is allowed to appear in the outer layers only. SN 2019muj provides a unique opportunity to link extremely low-luminosity SNe Iax to well-studied, brighter SNe Iax.
The progenitor of SN 2005cs in the Whirlpool Galaxy Maund, Justyn R.; Smartt, Stephen J.; Danziger, I. John
Monthly notices of the Royal Astronomical Society. Letters,
November 2005, Volume:
364, Issue:
1
Journal Article
Peer reviewed
Open access
The progenitor of SN 2005cs, in the galaxy M51, is identified in pre-explosion Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) imaging. Differential ...astrometry, with post-explosion ACS High Resolution Channel (HRC) F555W images, permitted the identification of the progenitor with an accuracy of 0.006 arcsec. The progenitor was detected in the F814W pre-explosion image with I= 23.3 ± 0.2, but was below the detection thresholds of the F435W and F555W images, with B < 24.8 and V < 25 at 5σ. Limits were also placed on the U- and R-band fluxes of the progenitor from pre-explosion HST Wide Field Planetary Camera 2 (WFPC2) F336W and F675W images. Deep images in the infrared from the Near Infra-red Imager (NIRI) on the Gemini North Telescope were taken 2 months prior to explosion, but the progenitor is not clearly detected on these. The upper limits for the JHK magnitudes of the progenitor were J < 21.9, H < 21.1 and K < 20.7. Despite having a detection in only one band, a restrictive spectral energy distribution of the progenitor star can be constructed and a robust case is made that the progenitor was a red supergiant with spectral type between mid-K and late-M. The spectral energy distribution allows a region in the theoretical Hertzsprung–Russell diagram to be determined that must contain the progenitor star. The initial mass of the star is constrained to be MZAMS= 9+3−2M⊙, which is very similar to the identified progenitor of the Type II-P SN 2003gd, and also consistent with upper mass limits placed on five other similar supernovae. The upper limit in the deep K-band image is significant in that it allows us to rule out the possibility that the progenitor was a significantly higher mass object enshrouded in a dust cocoon before core collapse. This is further evidence that the trend for Type II-P supernovae to arise in low- to moderate-mass red supergiants is real.
Abstract
We present the 30 minutes cadence Kepler/K2 light curve of the Type Ia supernova (SN Ia) SN 2018agk, covering approximately one week before explosion, the full rise phase, and the decline ...until 40 days after peak. We additionally present ground-based observations in multiple bands within the same time range, including the 1 day cadence DECam observations within the first ∼5 days after the first light. The Kepler early light curve is fully consistent with a single power-law rise, without evidence of any bump feature. We compare SN 2018agk with a sample of other SNe Ia without early excess flux from the literature. We find that SNe Ia without excess flux have slowly evolving early colors in a narrow range (
g
−
i
≈ −0.20 ± 0.20 mag) within the first ∼10 days. On the other hand, among SNe Ia detected with excess, SN 2017cbv and SN 2018oh tend to be bluer, while iPTF16abc’s evolution is similar to normal SNe Ia without excess in
g
−
i
. We further compare the Kepler light curve of SN 2018agk with companion-interaction models, and rule out the existence of a typical nondegenerate companion undergoing Roche lobe overflow at viewing angles smaller than 45°.
Abstract
Hydrogen-rich, core-collapse supernovae are typically divided into four classes: IIP, IIL, IIn, and IIb. Recent hydrodynamic modelling shows that circumstellar material is required to ...produce the early light curves of most IIP/IIL supernovae. In this scenario, IIL supernovae experience large amounts of mass-loss before exploding. We test this hypothesis on ASASSN-15oz, a Type IIL supernova. With extensive follow-up in the X-ray, UV, optical, IR, and radio, we present our search for signs of interaction and the mass-loss history indicated by their detection. We find evidence of short-lived intense mass-loss just prior to explosion from light-curve modelling, amounting in 1.5 M⊙ of material within 1800 R⊙ of the progenitor. We also detect the supernova in the radio, indicating mass-loss rates of 10−6 to 10−7 M⊙ yr−1 prior to the extreme mass-loss period. Our failure to detect the supernova in the X-ray and the lack of narrow emission lines in the UV, optical, and NIR do not contradict this picture and place an upper limit on the mass-loss rate outside the extreme period of <10−4 M⊙ yr−1. This paper highlights the importance gathering comprehensive data on more Type II supernovae to enable detailed modelling of the progenitor and supernova which can elucidate their mass-loss histories and envelope structures and thus inform stellar evolution models.
We present photometric and spectroscopic observations of the interacting transient SN 2009ip taken during the 2013 and 2014 observing seasons. We characterize the photometric evolution as a steady ...and smooth decline in all bands, with a decline rate that is slower than expected for a solely 56Co-powered supernova at late phases. No further outbursts or eruptions were seen over a two year period from 2012 December until 2014 December. SN 2009ip remains brighter than its historic minimum from pre-discovery images. Spectroscopically, SN 2009ip continues to be dominated by strong, narrow (≲2000 km s− 1) emission lines of H, He, Ca, and Fe. While we make tenuous detections of Fe ii λ7155 and O i λλ6300, 6364 lines at the end of 2013 June and the start of 2013 October, respectively, we see no strong broad nebular emission lines that could point to a core-collapse origin. In general, the lines appear relatively symmetric, with the exception of our final spectrum in 2014 May, when we observe the appearance of a redshifted shoulder of emission at +550 km s− 1. The lines are not blueshifted, and we see no significant near- or mid-infrared excess. From the spectroscopic and photometric evolution of SN 2009ip until 820 d after the start of the 2012a event, we still see no conclusive evidence for core-collapse, although whether any such signs could be masked by ongoing interaction is unclear.
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