We present a catalog of 93 very-well-observed nova light curves. The light curves were constructed from 229,796 individual measured magnitudes, with the median coverage extending to 8.0 mag below ...peak and 26% of the light curves following the eruption all the way to quiescence. Our time-binned light curves are presented in figures and as complete tabulations. We also calculate and tabulate many properties about the light curves, including peak magnitudes and dates, times to decline by 2, 3, 6, and 9 mag from maximum, the time until the brightness returns to quiescence, the quiescent magnitude, power-law indices of the decline rates throughout the eruption, the break times in this decline, plus many more properties specific to each nova class. We present a classification system for nova light curves based on the shape and the time to decline by 3 mag from the peak (t 3). The designations are 'S' for smooth light curves (38% of the novae), 'P' for plateaus (21%), 'D' for dust dips (18%), 'C' for cusp-shaped secondary maxima (1%), 'O' for quasi-sinusoidal oscillations superposed on an otherwise smooth decline (4%), 'F' for flat-topped light curves (2%), and 'J' for jitters or flares superposed on the decline (16%). Our classification consists of this single letter followed by the t 3 value in parentheses; so, for example, V1500 Cyg is S(4), GK Per is O(13), DQ Her is D(100), and U Sco is P(3).
Abstract The evolution of cataclysmic variables (CVs) is driven by period changes ( P ̇ ), for which the long-venerable consensus is the magnetic braking model (MBM). The MBM has its only distinctive ...assumption being a power-law “recipe” describing the angular momentum loss (AML) in the binary, producing a single unique evolutionary track with P ̇ as a function of the orbital period. This required prediction can be used to test the most-fundamental assumption of MBM, but it has never been tested previously. In this paper, I collect P ̇ measures for 52 CVs of all types. First, 44% of the CVs have positive P ̇ , with such being impossible in MBM. Second, even among the CVs with negative P ̇ , their P ̇ measures are always more negative than required by MBM, with an average deviation of 110×. Third, three CVs have large chaotic variations in P ̇ that are impossible for MBM, proving that some unknown mechanism exists and is operating that dominates for these systems. Fourth, the MBM does not account for the long-term effects on evolution arising from the large sudden period decreases seen across many nova events, with this unaccounted effect dominating for the majority of nova systems and changing the sign of the overall evolutionary P ̇ . Fifth, three recurrent novae are observed to suddenly change P ̇ by an order of magnitude across a nova event, with this being impossible in the MBM. In all, the required MBM P ̇ predictions all fail for my 52 CVs, usually by orders of magnitude, so the MBM AML-recipe is wrong by orders of magnitude.
V2487 Ophiuchi (V2487 Oph) is a recurrent nova with classical nova eruptions in 1900 and 1998, and it is also the most extreme known superflare star. These superflares are roughly hour-long flares ...with amplitudes and optical energies reaching up to 1.10 mag and 1039.21 erg, respectively, with the superflares recurring once a day. The V2487 Oph superflares are certainly operating with the same mechanism as all the other types of superflare stars, where magnetic loops are twisted and stretched until reconnection occurs, whereupon ambient electrons are accelerated to relativistic energies and then emit bremsstrahlung radiation from X-ray to radio. V2487 Oph is unique among known superflare stars in that one of the loop footprints is in an accretion disk. This exact mechanism was theoretically predicted by M. R. Hayashi and colleagues in 1996. Now, I have found two superflares recorded on Harvard archival photographs from 1941 and 1942. These two superflares have B-magnitude amplitudes of >1.83 and >2.00 mag and total radiated energies of 1042.4 and 1042.5 erg, respectively, with bolometric corrections. Each has emitted energies of ∼30 billion Carringtons, in units of the most energetic solar flare. Further, I find superflares in Zwicky Transient Factory light curves, so V2487 Oph has been superflaring from 1941 to 2023. For the observed number distribution of dN/dE = 4E−2 superflares per year, for E in units of 1041 erg, the emitted energy in superflare light is 1042.1 erg in each year, or 1044.1 erg from 1941 to 2023.
A type Ia supernova is thought to begin with the explosion of a white dwarf star. The explosion could be triggered by the merger of two white dwarfs (a 'double-degenerate' origin), or by mass ...transfer from a companion star (the 'single-degenerate' path). The identity of the progenitor is still controversial; for example, a recent argument against the single-degenerate origin has been widely rejected. One way to distinguish between the double- and single-degenerate progenitors is to look at the centre of a known type Ia supernova remnant to see whether any former companion star is present. A likely ex-companion star for the progenitor of the supernova observed by Tycho Brahe has been identified, but that claim is still controversial. Here we report that the central region of the supernova remnant SNR 0509-67.5 (the site of a type Ia supernova 400 ± 50 years ago, based on its light echo) in the Large Magellanic Cloud contains no ex-companion star to a visual magnitude limit of 26.9 (an absolute magnitude of M(V) = +8.4) within a region of radius 1.43 arcseconds. (This corresponds to the 3σ maximum distance to which a companion could have been 'kicked' by the explosion.) This lack of any ex-companion star to deep limits rules out all published single-degenerate models for this supernova. The only remaining possibility is that the progenitor of this particular type Ia supernova was a double-degenerate system.
The goal of the book is to cover the interdisciplinary field of nanoscience beginning with the physical principles and extending to synthesis (chemistry), materials sicnece, nanoelectronics, ...nanobiology, and nanomedicine -- in a concise manner but also taking into account the recent significant developments. Based on lecture courses given by the author at his university and other universities abroad, this volume features many figures reproduced from the original papers, which are selected in order to give a convenient and rapid insight into the various fields. The bibliography encompasses the most recent papers so the reader can find there reference to earlier work, and a subject index is included.
•Electrochemical treatment of AFFF-impacted groundwater was demonstrated.•A divided electrochemical cell was used.•PFOS and PFOA removal was greater than that observed in previous studies using MMO ...anodes.•Defluorination was observed for both PFOS and PFOA.•Other long-chain perfluorinated compounds also were treated.
Laboratory experiments were performed to evaluate the use of electrochemical treatment for the decomposition of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), as well as other perfluoroalkyl acids (PFAAs), in aqueous film forming foam (AFFF)-impacted groundwater collected from a former firefighter training area and PFAA-spiked synthetic groundwater. Using a commercially-produced Ti/RuO2 anode in a divided electrochemical cell, PFOA and PFOS decomposition was evaluated as a function of current density (0–20mA/cm2). Decomposition of both PFOA and PFOS increased with increasing current density, although the decomposition of PFOS did not increase as the current density was increased above 2.5mA/cm2. At a current density of 10mA/cm2, the first-order rate constants, normalized for current density and treatment volume, for electrochemical treatment of both PFOA and PFOS were 46×10−5 and 70×10−5 (min−1) (mA/cm2)−1 (L), respectively. Defluorination was confirmed for both PFOA and PFOS, with 58% and 98% recovery as fluoride, respectively (based upon the mass of PFOA and PFOS degraded). Treatment of other PFAAs present in the groundwater also was observed, with shorter chain PFAAs generally being more recalcitrant. Results highlight the potential for electrochemical treatment of PFAAs, particularly PFOA and PFOS, in AFFF-impacted groundwater.
The distances to Novae as seen by Gaia Schaefer, Bradley E
Monthly Notices of the Royal Astronomical Society,
12/2018, Letnik:
481, Številka:
3
Journal Article
Abstract
A newly recognized young Galactic supernova (SN) remnant, Pa 30 (G123.1+4.6), centered on a hot central star with a ∼16,000 km s
−1
wind velocity, has recently been proposed to be the result ...of a double-degenerate merger leading to an SN Iax event associated with the guest star of 1181 CE. Here we present deep optical S
ii
λλ
6716,6731 images of Pa 30 that reveal an extraordinary and highly structured nebula 170″ in diameter with dozens of long (5″–20″), radially aligned filaments with a convergence point near the hot central star. Optical spectra of filaments indicate a peak expansion velocity ≃1100 km s
−1
with electron densities of ≤100–700 cm
−3
and a thick shell-like structure resembling its appearance in 22
μ
m WISE images. No H
α
emission was seen (S
ii
λ
6716/H
α
>5), with the only other line emission detected being faint Ar
iii
λ
7136, suggesting a S- and Ar-rich but H-poor remnant. The nebula’s angular size, estimated 2.3 kpc distance, and 1100 km s
−1
expansion velocity are consistent with an explosion date around 1181 CE. The remnant’s unusual appearance may be due to the photoionization of wind-driven ejecta due to clump–wind interactions caused by the central star’s high-luminosity wind.
Objective: We evaluate and quantify the effects of human, robot, and environmental factors on perceived trust in human-robot interaction (HRI).
Background: To date, reviews of trust in HRI have been ...qualitative or descriptive. Our quantitative review provides a fundamental empirical foundation to advance both theory and practice.
Method: Meta-analytic methods were applied to the available literature on trust and HRI. A total of 29 empirical studies were collected, of which 10 met the selection criteria for correlational analysis and 11 for experimental analysis. These studies provided 69 correlational and 47 experimental effect sizes.
Results: The overall correlational effect size for trust was r̄ = +0.26, with an experimental effect size of d̄ = +0.71. The effects of human, robot, and environmental characteristics were examined with an especial evaluation of the robot dimensions of performance and attribute-based factors. The robot performance and attributes were the largest contributors to the development of trust in HRI. Environmental factors played only a moderate role.
Conclusion: Factors related to the robot itself, specifically, its performance, had the greatest current association with trust, and environmental factors were moderately associated. There was little evidence for effects of human-related factors.
Application: The findings provide quantitative estimates of human, robot, and environmental factors influencing HRI trust. Specifically, the current summary provides effect size estimates that are useful in establishing design and training guidelines with reference to robot-related factors of HRI trust. Furthermore, results indicate that improper trust calibration may be mitigated by the manipulation of robot design. However, many future research needs are identified.
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