Photometric and spectroscopic evolution of the peculiar Type IIn SN 2012ab

ABSTRACT We present an extensive (∼1200 d) photometric and spectroscopic monitoring of the Type IIn supernova (SN) 2012ab. After a rapid initial rise leading to a bright maximum (MR = −19.39 mag), the light curves show a plateau lasting about 2 months followed by a steep decline up to about 100 d. Only in the U band, the decline is constant in the same interval. At later phases, the light curves remain flatter than the 56Co decline, suggesting the increasing contribution of the interaction between SN ejecta with circumstellar material (CSM). Although heavily contaminated by emission lines of the host galaxy, the early spectral sequence (until 32 d) shows persistent narrow emissions, indicative of slow unshocked CSM, and the emergence of broad Balmer lines of hydrogen with P-Cygni profiles over a blue continuum, arising from a fast expanding SN ejecta. From about 2 months to ∼1200 d, the P-Cygni profiles are overcome by intermediate width emissions [full width at half-maximum (FWHM) ∼6000 km s−1], produced in the shocked region due to interaction. On the red wing, a red bump appears after 76 d, likely a signature of the onset of interaction of the receding ejecta with the CSM. The presence of fast material both approaching and then receding is suggestive that we are observing the SN along the axis of a jet-like ejection in a cavity devoid of or uninterrupted by CSM in the innermost regions.

Download Full-text

Extensions of the Wilson-Bappu Effect Among Very Luminous Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900145267 ◽

1978 ◽

Vol 80 ◽

pp. 59-62

Author(s):

Robert E. Stencel

Keyword(s):

Emission Lines ◽

Full Width ◽

Half Maximum ◽

Late Type ◽

New Class ◽

Line Core ◽

M Stars ◽

Type Giant

Twenty years ago, Wilson and Bappu (1957) published their observational correlation of MVand the logarithm of the full width at half maximum of the CaII K-line central emission for G, K and M stars. The technique was stated to have ± 0m.5 accuracy, while a tabulation of MV(K) by Wilson (1976) suggests the error may only be ± 0m.3. This accuracy makes the approach valuable for late-type supergiants since other methods suffer from comparable errors. However, for F through M supergiants (Ia, 0), circumstellar absorption obscures the chromospheric K-line core emission and excludes such objects from the Wilson-Bappu correlation. I report here on a new class of emission lines in late-type giant and supergiant spectra that exhibit MVcorrelated widths, yet are detectable among the brightest stars.

Download Full-text

Spectroscopic Studies of Laser-Based Far-Ultraviolet Plasma Light Source

Applied Sciences ◽

10.3390/app11156919 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6919

Author(s):

Majid Masnavi ◽

Martin Richardson

Keyword(s):

Dense Plasma ◽

Wavelength Region ◽

Spectroscopic Studies ◽

Radiation Hydrodynamics ◽

Full Width ◽

Half Maximum ◽

Laser Plasmas ◽

Series Of Experiments ◽

Far Ultraviolet ◽

Radiation Conversion

A series of experiments is described which were conducted to measure the absolute spectral irradiances of laser plasmas created from metal targets over the wavelength region of 123–164 nm by two separate 1.0 μm lasers, i.e., using 100 Hz, 10 ns, 2–20 kHz, 60–100 ns full-width-at-half-maximum pulses. A maximum radiation conversion efficiency of ≈ 3%/2πsr is measured over a wavelength region from ≈ 125 to 160 nm. A developed collisional-radiative solver and radiation-hydrodynamics simulations in comparison to the spectra detected by the Seya–Namioka-type monochromator reveal the strong broadband experimental radiations which mainly originate from bound–bound transitions of low-ionized charges superimposed on a strong continuum from a dense plasma with an electron temperature of less than 10 eV.

Download Full-text

Predicting the broad-lines polarization emitted by supermassive binary black holes

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834443 ◽

2019 ◽

Vol 623 ◽

pp. A56 ◽

Cited By ~ 3

Author(s):

D. Savić ◽

F. Marin ◽

L. Č. Popović

Keyword(s):

Black Holes ◽

Emission Lines ◽

Polarization Angle ◽

Broad Line ◽

Line Profiles ◽

Binary Black Holes ◽

True Nature ◽

Line Shapes ◽

Highly Sensitive ◽

Balmer Lines

Context. Some Type-1 active galactic nuclei (AGN) show extremely asymmetric Balmer lines with the broad peak redshifted or blueshifted by thousands of km s−1. These AGN may be good candidates for supermassive binary black holes (SMBBHs). The complex line shapes can be due to the complex kinematics of the two broad line regions (BLRs). Therefore other methods should be applied to confirm the SMBBHs. One of them is spectropolarimetry. Aims. We rely on numerical modeling of the polarimetry of binary black holes systems, since polarimetry is highly sensitive to geometry, in order to find the specific influence of supermassive binary black hole (SMBBH) geometry and dynamics on polarized parameters across the broad line profiles. We apply our method to SMBBHs in which both components are assumed to be AGN with distances at the subparsec scale. Methods. We used a Monte Carlo radiative transfer code that simulates the geometry, dynamics, and emission pattern of a binary system where two black holes are getting increasingly close. Each gravitational well is accompanied by its own BLR and the whole system is surrounded by an accretion flow from the distant torus. We examined the emission line deformation and predicted the associated polarization that could be observed. Results. We modeled scattering-induced broad line polarization for various BLR geometries with complex kinematics. We find that the presence of SMBBHs can produce complex polarization angle profiles φ and strongly affect the polarized and unpolarized line profiles. Depending on the phase of the SMBBH, the resulting double-peaked emission lines either show red or blue peak dominance, or both the peaks can have the same intensity. In some cases, the whole line profile appears as a single Gaussian line, hiding the true nature of the source. Conclusions. Our results suggest that future observation with the high resolution spectropolarimetry of optical broad emission lines could play an important role in detecting subparsec SMBBHs.

Download Full-text

Time to peak and full width at half maximum in MR perfusion: valuable indicators for monitoring moyamoya patients after revascularization

Scientific Reports ◽

10.1038/s41598-020-80036-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Adam Huang ◽

Chung-Wei Lee ◽

Hon-Man Liu

Keyword(s):

Study Data ◽

Unknown Etiology ◽

Dynamic Susceptibility ◽

Full Width ◽

Half Maximum ◽

Mr Perfusion ◽

Dynamic Susceptibility Contrast ◽

Time To Peak ◽

Mr Perfusion Imaging ◽

Outcome Monitoring

AbstractMoyamoya disease (MMD) is a chronic, steno-occlusive cerebrovascular disorder of unknown etiology. Surgical treatment is the only known effective method to restore blood flow to affected areas of the brain. However, there are lack of generally accepted noninvasive tools for therapeutic outcome monitoring. As dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) is the standard MR perfusion imaging technique in the clinical setting, we investigated a dataset of nineteen pediatric MMD patients with one preoperational and multiple periodic DSC MRI examinations for four to thirty-eight months after indirect revascularization. A rigid gamma variate model was used to derive two nondeconvolution-based perfusion parameters: time to peak (TTP) and full width at half maximum (FWHM) for monitoring transitional bolus delay and dispersion changes respectively. TTP and FWHM values were normalized to the cerebellum. Here, we report that 74% (14/19) of patients improve in both TTP and FWHM measurements, and whereof 57% (8/14) improve more noticeably on FWHM. TTP is in good agreement with Tmax in estimating bolus delay. Our study data also suggest bolus dispersion estimated by FWHM is an additional, informative indicator in pediatric MMD monitoring.

Download Full-text

Preparation of highly c-axis oriented AlN thin films on Hastelloy tapes with Y2O3 buffer layer for flexible SAW sensor applications

Functional Materials Letters ◽

10.1142/s1793604716500235 ◽

2016 ◽

Vol 09 (02) ◽

pp. 1650023 ◽

Cited By ~ 2

Author(s):

Bin Peng ◽

Jianying Jiang ◽

Guo Chen ◽

Lin Shu ◽

Jie Feng ◽

...

Keyword(s):

Buffer Layer ◽

Smooth Surface ◽

Piezoelectric Coefficient ◽

Piezoelectric Properties ◽

Mean Square ◽

Full Width ◽

Half Maximum ◽

Sensor Applications ◽

Saw Sensor ◽

Y2o3 Buffer Layer

Highly c-axis oriented aluminum nitrade (AlN) films were successfully deposited on flexible Hastelloy tapes by middle-frequency magnetron sputtering. The microstructure and piezoelectric properties of the AlN films were investigated. The results show that the AlN films deposited directly on the bare Hastelloy substrate have rough surface with root mean square (RMS) roughness of 32.43[Formula: see text]nm and its full width at half maximum (FWHM) of the AlN (0002) peak is [Formula: see text]. However, the AlN films deposited on the Hastelloy substrate with Y2O3 buffer layer show smooth surface with RMS roughness of 5.46[Formula: see text]nm and its FWHM of the AlN (0002) peak is only [Formula: see text]. The piezoelectric coefficient d[Formula: see text] of the AlN films deposited on the Y2O3/Hastelloy substrate is larger than three times that of the AlN films deposited on the bare Hastelloy substrate. The prepared highly c-axis oriented AlN films can be used to develop high-temperature flexible SAW sensors.

Download Full-text

Research of the anti-resonance pulse forming network and its application in the Marx generator

Laser and Particle Beams ◽

10.1017/s0263034616000641 ◽

2016 ◽

Vol 34 (4) ◽

pp. 675-686 ◽

Cited By ~ 12

Author(s):

Z.-L. Pan ◽

J.-H. Yang ◽

X.-B. Cheng

Keyword(s):

Equivalent Circuit ◽

Rise Time ◽

Pulse Width ◽

Marx Generator ◽

Full Width ◽

Half Maximum ◽

Compact Structure ◽

Fall Time ◽

Pulse Forming Network ◽

Load Pulse

AbstractAn anti-resonance pulse forming network (PFN) has been designed, analyzed, and tested for its application in generating quasi-square pulses. According to the circuit simulations, a compact generator based on two/three-section network was constructed. Two-section network is applied in the generator due to its compact structure, while three-section network is employed for generating pulses with higher quality. When two-section network is applied in the generator, the full-width at half-maximum of the load pulse is 400 ns, at the same time, its rise time, flat top and fall time are 90, 180 and 217 ns, respectively. When the three-section network is applied with the same pulse width of the load pulse, the rise time of the output decreases to 60 ns, while the flat top increases to 240 ns and the fall time reduces to 109 ns. Meanwhile, this kind of network could be used to shape the output pulses of generators whose equivalent circuit is LC series discharge network, such as MARX generator, into quasi-square pulses. And the preliminary experiment demonstrates that anti-resonance network could work well on four-stage Marx generators. A sine pulse generated by the four-stage Marx generator is shaped into a quasi-square pulse with voltage of 11.8 kV and pulse width about 110 ns based on two-section anti-resonance network.

Download Full-text

Photoluminescence of Erbium-Diffused Silicon

MRS Proceedings ◽

10.1557/proc-422-81 ◽

1996 ◽

Vol 422 ◽

Author(s):

H. Horiguchi ◽

T. Kinone ◽

R. Saito ◽

T. Kimura ◽

T. Ikoma

Keyword(s):

Room Temperature ◽

Crystalline Silicon ◽

Luminescence Spectra ◽

Main Peak ◽

Silicon Substrates ◽

Annealing Atmosphere ◽

Full Width ◽

Half Maximum ◽

Strong Luminescence ◽

Fine Structures

AbstractErbium films are evaporated on crystalline silicon substrates and are thermally diffused into silicon in an Ar+02 or H2 flow. Very sharp Er3+-related luminescence peaks are observed around 1.54 μ m.The main peak as well as the fine structures of the luminescence spectra depend on the annealing atmosphere, suggesting different luminescence centers. The full width at half maximum (FWHM) of the main peaks is ≤ 0.5nm at 20K. Thermal diffusion with Al films on top of the Er films is found to increase the intensity of the Er3+-related peaks greatly. The temperature dependence between 20 K and room temperature is relatively small, and a strong luminescence is obtained at room temperature.

Download Full-text

Supershort avalanche electron beam generation in gases

Laser and Particle Beams ◽

10.1017/s0263034608000670 ◽

2008 ◽

Vol 26 (4) ◽

pp. 605-617 ◽

Cited By ~ 40

Author(s):

V.F. Tarasenko ◽

E.H. Baksht ◽

A.G. Burachenko ◽

I.D. Kostyrya ◽

M.I. Lomaev ◽

...

Keyword(s):

High Pressure ◽

Electron Beam ◽

Atmospheric Pressure ◽

Electron Beams ◽

Solid Angle ◽

Generation Mechanism ◽

Full Width ◽

Half Maximum ◽

Electron Beam Pulse ◽

Supershort Avalanche Electron Beam

AbstractThis paper reports on the properties of a supershort avalanche electron beam generated in the air or other gases under atmospheric pressure and gives the analysis of a generation mechanism of supershort avalanche electron beam, as well as methods of such electron beams registration. It is reported that in the air under the pressure of 1 atm, a supershort (<100 ps) avalanche electron beam is formed in the solid angle more than 2π steradian. The electron beam has been obtained behind a 45 µm thick Al-Be foil in SF6 and Xe under the pressure of 2 atm, and in He, under the pressure of about 15 atm. It is shown that in SF6 under the high pressure (>1 atm) duration (full width at half maximum) of supershort avalanche electron beam pulse is about 150 ps.

Download Full-text

Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals

Nature Communications ◽

10.1038/s41467-021-22412-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Shoufeng Lan ◽

Xiaoze Liu ◽

Siqi Wang ◽

Hanyu Zhu ◽

Yawen Liu ◽

...

Keyword(s):

Time Reversal ◽

Room Temperature ◽

Photochemical Reactions ◽

Full Width ◽

Half Maximum ◽

A Value ◽

Device Applications ◽

Spectral Splitting ◽

Iron Garnet ◽

Spontaneous Magnetic Moment

AbstractThe interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.

Download Full-text

Retrieval of sodium number density profiles in the mesosphere and lower thermosphere from SCIAMACHY limb emission measurements

Atmospheric Measurement Techniques ◽

10.5194/amt-9-295-2016 ◽

2016 ◽

Vol 9 (1) ◽

pp. 295-311 ◽

Cited By ~ 3

Author(s):

M. P. Langowski ◽

C. von Savigny ◽

J. P. Burrows ◽

V. V. Rozanov ◽

T. Dunker ◽

...

Keyword(s):

Seasonal Variations ◽

Lower Thermosphere ◽

High Latitudes ◽

Full Width ◽

Half Maximum ◽

Number Density ◽

Data Set ◽

Density Profiles ◽

Atom Concentration ◽

Mesosphere And Lower Thermosphere

Abstract. An algorithm has been developed for the retrieval of sodium atom (Na) number density on a latitude and altitude grid from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) limb measurements of the Na resonance fluorescence. The results are obtained between 50 and 150 km altitude and the resulting global seasonal variations of Na are analyzed. The retrieval approach is adapted from that used for the retrieval of magnesium atom (Mg) and magnesium ion (Mg+) number density profiles recently reported by Langowski et al. (2014). Monthly mean values of Na are presented as a function of altitude and latitude. This data set was retrieved from the 4 years of spectroscopic limb data of the SCIAMACHY mesosphere and lower thermosphere (MLT) measurement mode (mid-2008 to early 2012). The Na layer has a nearly constant peak altitude of 90–93 km for all latitudes and seasons, and has a full width at half maximum of 5–15 km. Small but significant seasonal variations in Na are identified for latitudes less than 40°, where the maximum Na number densities are 3000–4000 atoms cm−3. At middle to high latitudes a clear seasonal variation with a winter maximum of up to 6000 atoms cm−3 is observed. The high latitudes, which are only measured in the summer hemisphere, have lower number densities, with peak densities being approximately 1000 Na atoms cm−3. The full width at half maximum of the peak varies strongly at high latitudes and is 5 km near the polar summer mesopause, while it exceeds 10 km at lower latitudes. In summer the Na atom concentration at high latitudes and at altitudes below 88 km is significantly smaller than that at middle latitudes. The results are compared with other observations and models and there is overall a good agreement with these.

Download Full-text