Related papers: Discovery of slow X-ray pulsations in the high-mas…
Rossi X-ray Timing Explorer All-Sky Monitor observations of the X-ray source 4U2206+54, previously proposed to be a Be star system, show the X-ray flux to be modulated with a period of approximately 9.6 days. If the modulation is due to…
Spin properties and spectral variations of high mass X-ray binary 4U 2206+54 are studied with long-term hard X-ray monitoring observations by INTEGRAL. A long-period X-ray pulsar of P_spin\sim 5558 s has been identified in 4U 2206+54. The…
The discovery of very slow pulsations (Pspin=5560s) has solved the long-standing question of the nature of the compact object in the high-mass X-ray binary 4U 2206+54 but has posed new ones. According to spin evolutionary models in close…
We report the timing and spectral studies of the accreting X-ray pulsar 4U 2206+54 using astrosat and hxmt observations taken in 2016 and 2020 respectively. X-ray pulsations from the system are detected by both missions. The astrosat…
U 2206+54 is a wind-fed high mass X-ray binary with a main-sequence donor star. The nature of its compact object was recently identified as a slow-pulsation magnetized neutron star. INTEGRAL/IBIS observations have a long-term hard X-ray…
4U 2206+54 is a high mass X-ray binary which has been suspected to contain a neutron star accreting from the wind of its companion BD +53 2790. Reig et al. have recently detected 5560 s period pulsations in both RXTE and INTEGRAL…
The hard X-ray source 4U 2206+54 is a peculiar high mass X-ray binary with a main-sequence donor star. Recent X-ray observations suggested that the compact object in 4U 2206+54 may be a neutron star. The X-ray emission comes from the…
A pointed observation of the low-luminosity galactic source 4U 2206+54 was carried out in November 1998 with BeppoSAX. The light curve of 4U 2206+54 shows erratic variability on a timescale of about 1 hour; neither hardness variations nor…
Massive X-ray binaries are usually classified depending on the properties of the donor star in classical, supergiant and Be X-ray binaries. The massive X-ray binary 4U 2206+54 does not fit in any of these groups, and deserves a detailed…
The recent discovery of a ~9.5-d period in the X-ray lightcurve of the massive X-ray binary 4U2206+54 has opened the possibility that it is a Be/X-ray binary with an unusually close orbit, which, together with its low intrinsic luminosity,…
The symbiotic X-ray binary 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its ~5.4h NS spin period is the longest among all known accretion-powered pulsars and exhibited large (~7%)…
Observations of the X-ray pulsar 4U 2206+54, performed over a 15-year span, show its period, which is now 5555 \pm 9 s, to increase drastically. Such behavior of the pulsar can be hardly explained in the frame of traditional scenarios of…
We describe observations of the 2003 outburst of the hard-spectrum X-ray transient 4U 1901+03 with the Rossi X-ray Timing Explorer. The outburst was first detected in 2003 February by the All-Sky Monitor, and reached a peak 2.5-25 keV flux…
4U 1954+319 was discovered 25 years ago, but only recently has a clear picture of its nature begun to emerge. We present for the first time a broad-band spectrum of the source and a detailed timing study using more than one year of…
Based on our new NuSTAR X-ray telescope data, we rule out any cyclotron line up to 60 keV in the spectra of the high mass X-ray binary 4U2206+54. In particular, we do not find any evidence of the previously claimed line around 30 keV,…
We discovered a periodicity at about 8.7s from the X--ray sources 4U0142+61, previously considered a possible black hole candidate on the basis of its ultrasoft spectrum. The pulsations are visible only in the 1--4 keV energy range, during…
We present new radial velocities of the high-mass X-ray binary star 4U 2206+54 based on optical spectra obtained with the Coude spectrograph at the 2m RCC telescope at the Rozhen National Astronomical Observatory, Bulgaria in the period…
The Burst Alert Telescope (BAT) on board Swift has accumulated extensive light curves for 265 sources (not including GRBs) in the energy range 14 to 200 keV. We present here a summary of searches for periodic modulation in the flux from…
We present results from several years of fast optical photometry of 4U0614+091 (V1055 Orionis), a candidate ultracompact X-ray binary most likely consisting of a neutron star and a degenerate secondary. We find evidence for strong…
An overview of the results of observations for the transient X-ray pulsar 4U 0115+63, a member of a binary system with a Be star, since its discovery to the present day (~40 years) based on data from more than dozen observatories and…