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We investigate numerically the time evolution of velocity and magnetic field fluctuations in a coronal loop, focusing on the dynamics due to both phase mixing and turbulent cascade. The intensity, doppler velocity and non-thermal broadening…

Very long baseline interferometry (VLBI) provides the resolution needed to make precision measurements of a pulsar's parallax and proper motion. In making these measurements, the astronomer is faced with difficult calibration problems and a…

Astrophysics · Physics 2007-05-23 Walter Brisken

We present high-precision timing of five millisecond pulsars (MSPs) carried out for more than seven years; four pulsars are in binary systems and one is isolated. We are able to measure the pulsars' proper motions and derive an estimate for…

We studied the turbulence spectrum of the local interstellar plasma in the direction of PSR J0437-4715, on the basis of our observations and those reported earlier by others. We combine these data to form a structure function for the…

Astrophysics · Physics 2009-11-11 T. V. Smirnova , C. R. Gwinn , V. I. Shishov

The unparalleled photometric data obtained by NASA's Kepler Space Telescope has led to an improved understanding of stellar structure and evolution - in particular for solar-like oscillators in this context. Binary stars are fascinating…

Accurate distances to pulsars can be used for a variety of studies of the Galaxy and its electron content. However, most distance measures to pulsars have been derived from the absorption (or lack thereof) of pulsar emission by Galactic HI…

Astrophysics of Galaxies · Physics 2012-10-02 J. P. W. Verbiest , J. M. Weisberg , A. A. Chael , K. J. Lee , D. R. Lorimer

Direction-dependent instrumental polarisation introduces wide-field polarimetric aberrations and limits the dynamic range of low-frequency interferometric images. We therefore provide a detailed two-dimensional analysis of the Giant…

Instrumentation and Methods for Astrophysics · Physics 2014-07-03 J. S. Farnes

Signals from radio pulsars show a wavelength-dependent delay due to dispersion in the interstellar plasma. At a typical observing wavelength, this delay can vary by tens of microseconds on five-year time scales, far in excess of signals of…

Sensitive measurements of the linearly polarized spectra of stars can be used to deduce geometric properties of their otherwise unresolved circumstellar environments. This paper describes some of the evidence for optical pumping and…

Solar and Stellar Astrophysics · Physics 2015-03-17 J. R. Kuhn , B Geiss , D. M. Harrington

Statistical characterization of secondary subsystems in binaries helps to distinguish between various scenarios of multiple-star formation. The DSSI speckle instrument was used at the Gemini-N telescope for several hours in 2015 July to…

Solar and Stellar Astrophysics · Physics 2016-10-26 Andrei Tokovinin , Elliott P. Horch

We combine single- and two-photon interference procedures for characterizing any multi-port linear optical interferometer accurately and precisely. Accuracy is achieved by estimating and correcting systematic errors that arise due to…

Quantum Physics · Physics 2016-03-03 Ish Dhand , Abdullah Khalid , He Lu , Barry C. Sanders

This paper considers scattering screens that have arbitrary spatial variations of scattering strength transverse to the line of sight, including screens that are spatially well confined, such as disks and filaments. We calculate the…

Astrophysics · Physics 2009-10-31 J. M. Cordes , T. Joseph W. Lazio

The obliquity of a terrestrial planet is an important clue about its formation and critical to its climate. Previous studies using simulated photometry of Earth show that continuous observations over most of a planet's orbit can be inverted…

Earth and Planetary Astrophysics · Physics 2018-03-02 Joel C. Schwartz , Clara Sekowski , Hal M. Haggard , Eric Pallé , Nicolas B. Cowan

We have monitored a large sample of millisecond pulsars using the 100-m Effelsberg radio telescope in order to compare their radio emission properties to the slowly rotating population. With some notable exceptions, our findings suggest…

Timing pulses of pulsars has proved to be a most powerful technique useful to a host of research areas in astronomy and physics. Importantly, the precision of this timing is not only affected by radiometer noise, but also by intrinsic pulse…

High Energy Astrophysical Phenomena · Physics 2015-05-28 K. Liu , J. P. W. Verbiest , M. Kramer , B. W. Stappers , W. van Straten , J. M. Cordes

At present, the principal limitation on the resolution and contrast of astronomical imaging instruments comes from aberrations in the optical path, which may be imposed by the Earth's turbulent atmosphere or by variations in the alignment…

Instrumentation and Methods for Astrophysics · Physics 2015-10-23 Benjamin Pope , Peter Tuthill , Sasha Hinkley , Michael J. Ireland , Alexandra Greenbaum , Alexey Latyshev , John D. Monnier , Frantz Martinache

A standard binary microlensing event lightcurve allows just two parameters of the lensing system to be measured: the mass ratio of the companion to its host, and the projected separation of the components in units of the Einstein radius.…

Astrophysics of Galaxies · Physics 2011-03-17 Matthew T. Penny , Shude Mao , Eamonn Kerins

Spatio-spectral properties of twin beams at their transition from low to high intensities are analyzed in parametric and paraxial approximations using the decomposition into paired spatial and spectral modes. Intensity auto- and…

Quantum Physics · Physics 2016-01-05 Jan Perina

The growing ``Hubble tension'' has prompted the need for precise measurements of cosmological distances. This paper demonstrates a purely geometric approach for determining the distance to extragalactic binaries through a joint analysis of…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-13 Yu-Yang Songsheng , Jian-Min Wang , Yuan Cao , XueFei Chen , JianPing Xiong , Zhi-Xiang Zhang , Rong-Gen Cai

We present results of more than three decades of timing measurements of the first known binary pulsar, PSR B1913+16. Like most other pulsars, its rotational behavior over such long time scales is significantly affected by small-scale…

Astrophysics of Galaxies · Physics 2011-06-08 Joel M. Weisberg , David J. Nice , Joseph H. Taylor
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