scholarly journals Astrophysical parameters and orbital solution of the peculiar X-ray transient IGR J00370+6122

2014 ◽  
Vol 566 ◽  
pp. A131 ◽  
Author(s):  
A. González-Galán ◽  
I. Negueruela ◽  
N. Castro ◽  
S. Simón-Díaz ◽  
J. Lorenzo ◽  
...  
Keyword(s):  
X Ray ◽  
Orbital Solution

scholarly journals Timing of the accreting millisecond pulsar IGR J17591–2342: evidence of spin-down during accretion

2020 ◽  
Vol 495 (2) ◽  
pp. 1641-1649
Author(s):  
A Sanna ◽  
L Burderi ◽  
K C Gendreau ◽  
T Di Salvo ◽  
P S Ray ◽  
...  
Keyword(s):  
Neutron Star ◽  
Timing Analysis ◽  
Millisecond Pulsar ◽  
Pulse Profile ◽  
X Ray ◽  
Observed Behaviour ◽  
October 17 ◽  
Refined Estimate ◽  
Star Surface ◽  
Orbital Solution

ABSTRACT We report on the phase-coherent timing analysis of the accreting millisecond X-ray pulsar IGR J17591–2342, using Neutron Star Interior Composition Explorer (NICER) data taken during the outburst of the source between 2018 August 15 and 2018 October 17. We obtain an updated orbital solution of the binary system. We investigate the evolution of the neutron star spin frequency during the outburst, reporting a refined estimate of the spin frequency and the first estimate of the spin frequency derivative ($\dot{\nu }\sim -7\times 10^{-14}$ Hz s−1), confirmed independently from the modelling of the fundamental frequency and its first harmonic. We further investigate the evolution of the X-ray pulse phases adopting a physical model that accounts for the accretion material torque as well as the magnetic threading of the accretion disc in regions where the Keplerian velocity is slower than the magnetosphere velocity. From this analysis we estimate the neutron star magnetic field Beq = 2.8(3) × 108 G. Finally, we investigate the pulse profile dependence on energy finding that the observed behaviour of the pulse fractional amplitude and lags as a function of energy is compatible with the down-scattering of hard X-ray photons in the disc or the neutron star surface.

scholarly journals The Spectral Distribution of Be/X-ray Transients Implies Supernova Kicks

2000 ◽  
Vol 175 ◽  
pp. 709-712
Author(s):  
Ignacio Negueruela
Keyword(s):  
Mass Transfer ◽  
Binary System ◽  
Spectral Distribution ◽  
Alternative Model ◽  
Large Fraction ◽  
Supernova Explosion ◽  
X Ray ◽  
Massive Component ◽  
X Ray Binaries ◽  
Orbital Solution

AbstractBe/X-ray binaries are generally assumed to have formed as the result of the evolution of moderately massive binaries in which mass is transferred semi-conservatively from the originally more massive component on to its companion. An alternative model proposes a binary system with a very massive component which loses a large fraction of its mass via very unconservative mass transfer. This scenario allows the formation of Be/X-ray binaries without requiring an asymmetric supernova explosion. We show that the observed properties of most Be/X-ray binaries for which an orbital solution has been found are incompatible with this model.

scholarly journals Orbital Period Variation in the Chromospherically Active Binary FF UMa (2RE J0933+624)

2006 ◽  
Vol 2 (S240) ◽  
pp. 706-713
Author(s):  
M.C. Gálvez ◽  
D. Montes ◽  
M.J. Fernández-Figueroa ◽  
E. De Castro ◽  
M. Cornide
Keyword(s):  
Angular Momentum ◽  
High Resolution ◽  
Orbital Period ◽  
Period Variation ◽  
Convective Envelope ◽  
X Ray ◽  
Secondary Star ◽  
Julian Date ◽  
Hα Emission ◽  
Orbital Solution

AbstractWe present here a detailed study of FF UMa (2RE J0933+624), a recently discovered, X-ray/EUV selected, active binary system with strong Hα emission. By using high-resolution echelle spectroscopic observations taken during five observing runs from 1998 to 2004, we derived precise radial velocities that allowed us to determine the orbital solution of the system at different epochs. Analyzing these orbital solutions, together with a previous one determined in 1993 by other authors, we have found a change in the heliocentric Julian date on conjunction (Tconj) that can be explained by a change with time in the orbital period of the system. The relative amplitude of the orbital period variation derived from these data was dP/P ≈ 5 x 10−4, which is larger than the variations found in other similar chromospherically active binaries like AR Lac and HR 1099. This orbital period variation can be related (Applegate 1992; Lanza 1998, 2006) with the modulation of the gravitational quadrupole-moment of its magnetically active secondary star produced by angular momentum exchanges within its convective envelope. In addition, using these observations, we have determined the stellar parameters of the components and we have carried out a study of the chromospheric activity using all the optical indicators from Ca ii H&K to Ca ii IRT lines.

scholarly journals Orbit and intrinsic spin-up of the newly discovered transient X-ray pulsar Swift J0243.6+6124

2018 ◽  
Vol 613 ◽  
pp. A19 ◽  
Author(s):  
V. Doroshenko ◽  
S. Tsygankov ◽  
A. Santangelo
Keyword(s):  
Neutron Star ◽  
Gamma Ray ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Orbital Solution

We present the orbital solution for the newly discovered transient Be X-ray binary Swift J0243.6+6124 based on the data from the gamma-ray burst monitor on board Fermi obtained during the October 2017 outburst. We model the Doppler induced and intrinsic spin variations of the neutron star assuming that the latter is driven by accretion torque, and we discuss the implications of the observed spin variations for the parameters of the neutron star and the binary. In particular, we conclude that the neutron star must be strongly magnetized, and estimate the distance to the source at ~5 kpc.

scholarly journals THE TRANSIENT ACCRETING X-RAY PULSAR XTE J1946+274: STABILITY OF X-RAY PROPERTIES AT LOW FLUX AND UPDATED ORBITAL SOLUTION

2015 ◽  
Vol 815 (1) ◽  
pp. 44 ◽  
Author(s):  
Diana M. Marcu-Cheatham ◽  
Katja Pottschmidt ◽  
Matthias Kühnel ◽  
Sebastian Müller ◽  
Sebastian Falkner ◽  
...  
Keyword(s):  
X Ray ◽  
Orbital Solution

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

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