scholarly journals Optical Modulation in the X-Ray Binary 4U 1543–624 Revisited

2015 ◽  
Vol 32 ◽  
Author(s):  
Z. Wang ◽  
A. Tziamtzis ◽  
D. L. Kaplan ◽  
D. Chakrabarty
Keyword(s):  
Optical Imaging ◽  
Inclination Angle ◽  
Orbital Period ◽  
Optical Modulation ◽  
Time Resolved ◽  
Sinusoidal Modulation ◽  
X Ray ◽  
The Stability ◽  
High Cadence ◽  
Linear Decay

AbstractThe X-ray binary 4U 1543–624 has been provisionally identified as an ultra-compact system with an orbital period of ≃ 18 min. We have carried out time-resolved optical imaging of the binary to verify the ultra-short orbital period. Using 140 min of high-cadence r′-band photometry, we recover the previously-seen sinusoidal modulation and determine a period P = 18.20 ± 0.09 min. In addition, we also see a 7.0 × 10−4 mag min−1 linear decay, likely related to variations in the source's accretion activity. Assuming that the sinusoidal modulation arises from X-ray heating of the inner face of the companion star, we estimate a distance of 6.0–6.7 kpc and an inclination angle of 34°–61° (90% confidence) for the binary. Given the stability of the modulation, we can confirm that the modulation is orbital in origin and 4U 1543–624 is an ultra-compact X-ray binary.

Time-Resolved Imaging of Correlation-Driven Charge Migration in Light-Induced Molecular Magnets by X-ray Scattering

2020 ◽  
Author(s):  
Jean-Christophe Tremblay ◽  
Gunter Hermann ◽  
Vincent Pohl ◽  
Gopal Dixit
Keyword(s):  
Molecular Magnets ◽  
Time Dependent ◽  
Electron Dynamics ◽  
Charge Migration ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Induced Charge ◽  
Time Resolved Imaging ◽  
The Stability

In this contribution, we investigate the effect of correlation-induced charge migration on the stability of light-induced molecular magnets. Laser-driven electron dynamics is simulated using density-matrix based time-dependent configuration interaction. The...

scholarly journals FemtoSpeX: a versatile optical pump–soft X-ray probe facility with 100 fs X-ray pulses of variable polarization

2014 ◽  
Vol 21 (5) ◽  
pp. 1090-1104 ◽  
Author(s):  
Karsten Holldack ◽  
Johannes Bahrdt ◽  
Andreas Balzer ◽  
Uwe Bovensiepen ◽  
Maria Brzhezinskaya ◽  
...  
Keyword(s):  
Laser System ◽  
X Ray Diffraction ◽  
Optical Pump ◽  
Time Resolved ◽  
Transient Phenomena ◽  
X Ray ◽  
User Facility ◽  
Average Flux ◽  
The Stability ◽  
Electron Storage Rings

Here the major upgrades of the femtoslicing facility at BESSY II (Khanet al., 2006) are reviewed, giving a tutorial on how elliptical-polarized ultrashort soft X-ray pulses from electron storage rings are generated at high repetition rates. Employing a 6 kHz femtosecond-laser system consisting of two amplifiers that are seeded by one Ti:Sa oscillator, the total average flux of photons of 100 fs duration (FWHM) has been increased by a factor of 120 to up to 106 photons s−1(0.1% bandwidth)−1on the sample in the range from 250 to 1400 eV. Thanks to a new beamline design, a factor of 20 enhanced flux and improvements of the stability together with the top-up mode of the accelerator have been achieved. The previously unavoidable problem of increased picosecond-background at higher repetition rates, caused by `halo' photons, has also been solved by hopping between different `camshaft' bunches in a dedicated fill pattern (`3+1 camshaft fill') of the storage ring. In addition to an increased X-ray performance at variable (linear and elliptical) polarization, the sample excitation in pump–probe experiments has been considerably extended using an optical parametric amplifier that supports the range from the near-UV to the far-IR regime. Dedicated endstations covering ultrafast magnetism experiments based on time-resolved X-ray circular dichroism have been either upgraded or, in the case of time-resolved resonant soft X-ray diffraction and reflection, newly constructed and adapted to femtoslicing requirements. Experiments at low temperatures down to 6 K and magnetic fields up to 0.5 T are supported. The FemtoSpeX facility is now operated as a 24 h user facility enabling a new class of experiments in ultrafast magnetism and in the field of transient phenomena and phase transitions in solids.

scholarly journals Time Resolved Circular Polarimetry of White Dwarf Pulsars

1982 ◽  
Vol 69 ◽  
pp. 399-401
Author(s):  
W. Krzeminski ◽  
J.D. Landstreet ◽  
I. Thompson
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
White Dwarfs ◽  
Radiation Mechanisms ◽  
Time Resolved ◽  
X Ray ◽  
Rotation Periods ◽  
Accretion Process ◽  
Cataclysmic Binaries ◽  
Synchronous Rotation

There are two recognized subsets of cataclysmic binaries that contain white dwarfs: the AM Her stars, whose white dwarf components are sufficiently magnetized to ensure synchronous rotation with the orbital period, and the DQ Her stars, which do not maintain synchronism and probably have been spun up by mass accretion. Both groups of stars, recognized also as X-ray sources, are important as probes of the accretion process, and the radiation mechanisms in the vicinity of the white dwarf. So far, we know five objects belonging to the former group (AM Her, AN UMa, VV Pup, 2A 0311-227, and PG 1550+191), and seven falling into the latter: WZ Sge, AE Aqr, V533 Her, DQ Her, V1223 Sgr, H2252-035, and EX Hya, with the corresponding rotation periods of their white dwarf primaries of 28, 33, 64, 71, 794, 805, and 4020 s, respectively. While the main observational and theoretical efforts have been focussed on the AM Her class, the DQ Her binaries have been investigated to much lesser extent. This is probably because the DQ Her stars have been recognized only very recently as a homogeneous class.

scholarly journals ASASSN-14ho: Longest-period dwarf nova with multiple rebrightenings

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Taichi Kato
Keyword(s):  
Mass Transfer ◽  
Radial Velocity ◽  
Accretion Disks ◽  
Orbital Period ◽  
Formal Solution ◽  
Dwarf Novae ◽  
X Ray ◽  
Dwarf Nova ◽  
Orbital Periods ◽  
The Stability

Abstract The post-outburst rebrightening phenomenon in dwarf novae and X-ray novae is still one of the most challenging subjects for theories of accretion disks. It has been widely recognized that post-outburst rebrightenings are a key feature of WZ Sge-type dwarf novae, which predominantly have short (≲0.06 d) orbital periods. The author found four post-outburst rebrightenings in ASASSN-14ho during its 2014 outburst, whose orbital period was recently measured to be exceptionally long [0.24315(10) d]. Using the formal solution of the radial velocity study in the literature, this paper discusses the possibility that this object could be an SU UMa-type dwarf nova near the stability border of the 3 : 1 resonance, despite its exceptionally long orbital period. Such objects are considered to be produced if mass transfer occurs after the secondary has undergone significant nuclear evolution, and they may be hidden in a significant number of dwarf novae showing multiple post-outburst rebrightenings.

scholarly journals Optical Spectroscopy of HD102567 (4U1145-61)

1982 ◽  
Vol 98 ◽  
pp. 151-154 ◽  
Author(s):  
Eduardo Janot Pacheco ◽  
C. Chevalier ◽  
S. A. Ilovaisky
Keyword(s):  
Optical Spectroscopy ◽  
Inclination Angle ◽  
Orbital Period ◽  
Rotation Velocity ◽  
Optical Spectra ◽  
Optical Counterpart ◽  
X Ray

Analysis of optical spectra of HD102567 (HEN 715), the optical counterpart of the X-ray source 4U1145-61 is presented. Estimates of the star's rotation velocity, inclination angle, distance and envelope characteristics are given. Some consequences of the possible existence of a 190d orbital period for this Be/X-ray sources are discussed.

A short-pulse X-ray beamline for spectroscopy and scattering

2014 ◽  
Vol 21 (5) ◽  
pp. 1194-1199
Author(s):  
R. Reininger ◽  
E. M. Dufresne ◽  
M. Borland ◽  
M. A. Beno ◽  
L. Young ◽  
...  
Keyword(s):  
Photon Energy ◽  
Materials Science ◽  
Short Pulse ◽  
Optical Design ◽  
High Repetition Rate ◽  
Light Sources ◽  
Time Resolved ◽  
X Ray ◽  
Central Cone ◽  
The Stability

Experimental facilities for picosecond X-ray spectroscopy and scattering based on RF deflection of stored electron beams face a series of optical design challenges. Beamlines designed around such a source enable time-resolved diffraction, spectroscopy and imaging studies in chemical, condensed matter and nanoscale materials science using few-picosecond-duration pulses possessing the stability, high repetition rate and spectral range of synchrotron light sources. The RF-deflected chirped electron beam produces a vertical fan of undulator radiation with a correlation between angle and time. The duration of the X-ray pulses delivered to experiments is selected by a vertical aperture. In addition to the radiation at the fundamental photon energy in the central cone, the undulator also emits the same photon energy in concentric rings around the central cone, which can potentially compromise the time resolution of experiments. A detailed analysis of this issue is presented for the proposed SPXSS beamline for the Advanced Photon Source. An optical design that minimizes the effects of off-axis radiation in lengthening the duration of pulses and provides variable X-ray pulse duration between 2.4 and 16 ps is presented.

Studying the H-alpha line of the B[ e ] supergiant binary GG Carinae using high-cadence optical spectroscopy

2018 ◽  
Vol 14 (S346) ◽  
pp. 123-124
Author(s):  
Augustus Porter ◽  
Katherine Blundell ◽  
Steven Lee
Keyword(s):  
Optical Spectroscopy ◽  
Orbital Period ◽  
Equivalent Width ◽  
Spectroscopy Data ◽  
Absorption Component ◽  
X Ray ◽  
X Ray Binaries ◽  
Circumstellar Environment ◽  
High Cadence

AbstractWe present a case study of GG Carinae (GG Car), a Galactic B[ e ] supergiant binary having significant eccentricity (0.28), based on Global Jet Watch spectroscopy data which has been collecting high-time-sampled optical spectra since early 2015. GG Car has so far not been observed in the X-ray band, however it is of similar phenomenology to known X-ray binaries and may therefore be an obscured X-ray source. We have discovered that the absorption component of the H-alpha line displays a ∼62-478-day period in both equivalent width and wavelength centroid indicating cycles in the dynamics of the circumstellar environment, such as precession of the circumbinary or circumprimary disk. Circumbinary disk precession is an as-of-yet underexplored origin of super-orbital variations in the X-ray flux of X-ray binaries, since the rate of precession is generally much longer than the orbital period of the inner binary.

scholarly journals A 2 day orbital period for a redback millisecond pulsar candidate in the globular cluster NGC 6397

2021 ◽  
Author(s):  
Manuel Pichardo Marcano ◽  
L E Rivera Sandoval ◽  
Thomas J Maccarone ◽  
Yue Zhao ◽  
Craig O Heinke
Keyword(s):  
Globular Cluster ◽  
Orbital Period ◽  
Globular Clusters ◽  
Variable Star ◽  
Optical Modulation ◽  
Optical Variability ◽  
Millisecond Pulsar ◽  
X Ray ◽  
Strong Candidate ◽  
Pulsar Searches

Abstract We report optical modulation of the companion to the X-ray source U18 in the globular cluster NGC 6397. U18, with combined evidence from radio and X-ray measurements, is a strong candidate as the second redback in this cluster, initially missed in pulsar searches. This object is a bright variable star with an anomalous red colour and optical variability (∼0.2 mag in amplitude) with a periodicity ∼1.96 days that can be interpreted as the orbital period. This value corresponds to the longest orbital period for known redback candidates and confirmed systems in Galactic globular clusters and one of the few with a period longer than 1 day.

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Fractionation of polymethylene chains: An electron crystallographic investigation

1986 ◽  
Vol 44 ◽  
pp. 794-795
Author(s):  
Douglas L. Dorset
Keyword(s):  
Cross Section ◽  
Binary Systems ◽  
Linear Chain ◽  
Pure Component ◽  
Organic Substrates ◽  
Crystallographic Investigation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Sizes ◽  
The Stability

A variety of linear chain materials exist as polydisperse systems which are difficultly purified. The stability of continuous binary solid solutions assume that the Gibbs free energy of the solution is lower than that of either crystal component, a condition which includes such factors as relative molecular sizes and shapes and perhaps the symmetry of the pure component crystal structures.Although extensive studies of n-alkane miscibility have been carried out via powder X-ray diffraction of bulk samples we have begun to examine binary systems as single crystals, taking advantage of the well-known enhanced scattering cross section of matter for electrons and also the favorable projection of a paraffin crystal structure posited by epitaxial crystallization of such samples on organic substrates such as benzoic acid.

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