Search results for "Orbital motion"

Erratum to: “A quark model analysis of orbital angular momentum” [Phys. Lett. B 460 (1999) 8–16]

2000

X-Ray Eclipse Time Delays in 4U2129+47

2007

4U 2129+47 was discovered in the early 80's and classified as an accretion disk corona source due to its broad and partial X-ray eclipses. The 5.24 hr binary orbital period was inferred from the X-ray and optical light curve modulation, implying a late K or M spectral type companion star. The source entered a low state in 1983, during which the optical modulation disappeared and an F8 IV star was revealed, suggesting that 4U 2129+47 might be part of a triple system. The nature of 4U 2129+47 has since been investigated, but no definitive conclusion has been reached. Here, we present timing and spectral analyses of two XMM-Newton observations of this source, carried out in May and June, 2005.…

Measuring the spin up of the Accreting Millisecond Pulsar XTE J1751-305

2007

We perform a timing analysis on RXTE data of the accreting millisecond pulsar XTE J1751-305 observed during the April 2002 outburst. After having corrected for Doppler effects on the pulse phases due to the orbital motion of the source, we performed a timing analysis on the phase delays, which gives, for the first time for this source, an estimate of the average spin frequency derivative = (3.7 +/- 1.0)E-13 Hz/s. We discuss the torque resulting from the spin-up of the neutron star deriving a dynamical estimate of the mass accretion rate and comparing it with the one obtained from X-ray flux. Constraints on the distance to the source are discussed, leading to a lower limit of \sim 6.7 kpc.

A VLBI study of the wind-wind collision region in the massive multiple HD 167971

2019

Context. Colliding winds in massive binaries are able to accelerate particles up to relativistic speeds as the result of the interaction between the winds of the different stellar components. HD 167971 exhibits this phenomenon which makes it a strong radio source. Aims. We aim at characterizing the morphology of the radio emission and its dependence on the orbital motion, traced independently by near-infrared (NIR) interferometry of both the spectroscopic binary and the tertiary component comprising HD 167971. Methods. We analyze 2006 and 2016 very long baseline interferometric data at C and X bands. We complement our analysis with a geometrical model of the wind-wind collision region and a…