Search Publications
Prolonged sub-luminous state of the new transitional pulsar candidate CXOU J110926.4‑650224
Rea, Nanda; Coti Zelati, Francesco; Torres, Diego F. +12 more
We report on a multi-wavelength study of the unclassified X-ray source CXOU J110926.4‑650224 (J1109). We identified the optical counterpart as a blue star with a magnitude of ∼20.1 (3300–10500 Å). The optical emission was variable on timescales from hundreds to thousands of seconds. The spectrum showed prominent emission lines with variable profil…
Revealing the cosmic evolution of boxy/peanut-shaped bulges from HST COSMOS and SDSS
Debattista, Victor P.; Erwin, Peter; Lintott, Chris +1 more
Vertically thickened bars, observed in the form of boxy/peanut (B/P) bulges, are found in the majority of massive barred disc galaxies in the local Universe, including our own. B/P bulges indicate that their host bars have suffered violent bending instabilities driven by anisotropic velocity distributions. We investigate for the first time how the…
Measuring the local matter density using Gaia DR2
Widmark, A.
Aims: We determine the total dynamical matter density in the solar neighbourhood using the second Gaia data release (DR2).
Methods: The dynamical matter density distribution is inferred in a framework of a Bayesian hierarchical model, which accounts for position and velocity of all individual stars, as well as the full error covariance m…
K2-264: a transiting multiplanet system in the Praesepe open cluster
Cochran, William D.; Endl, Michael; Tamura, Motohide +31 more
Planet host stars with well-constrained ages provide a rare window to the time domain of planet formation and evolution. The NASA K2 mission has enabled the discovery of the vast majority of known planets transiting stars in clusters, providing a valuable sample of planets with known ages and radii. We present the discovery of two planets transiti…
On the usefulness of existing solar wind models for pulsar timing corrections
Dettmar, R. -J.; Kramer, M.; Zucca, P. +15 more
Dispersive delays due to the solar wind introduce excess noise in high-precision pulsar timing experiments, and must be removed in order to achieve the accuracy needed to detect, e.g., low-frequency gravitational waves. In current pulsar timing experiments, this delay is usually removed by approximating the electron density distribution in the sol…
Advances in Understanding High-Mass X-ray Binaries with INTEGRALand Future Directions
Torres, Diego F.; Li, Jian; Rothschild, Richard E. +48 more
High mass X-ray binaries are among the brightest X-ray sources in the Milky Way, as well as in nearby Galaxies. Thanks to their highly variable emissions and complex phenomenology, they have attracted the interest of the high energy astrophysical community since the dawn of X-ray Astronomy. In more recent years, they have challenged our comprehens…
A new weak-field magnetic DA white dwarf in the local 20 pc volume. The frequency of magnetic fields in DA stars
Bagnulo, S.; Landstreet, J. D.
We report the discovery of a new magnetic DA white dwarf (WD), WD 0011 - 721, which is located within the very important 20 pc volume-limited sample of the closest WDs to the Sun. This star has a mean field modulus ⟨|B|⟩ of 343 kG, and from the polarisation signal we deduce a line-of-sight field component of 75 kG. The magnetic field is sufficient…
Deep Chandra Survey of the Small Magellanic Cloud. III. Formation Efficiency of High-mass X-Ray Binaries
Williams, Benjamin F.; Zezas, Andreas; Drake, Jeremy J. +12 more
We have compiled the most complete census of high-mass X-ray binaries (HMXBs) in the Small Magellanic Cloud with the aim to investigate the formation efficiency of young accreting binaries in its low-metallicity environment. In total, we use 123 X-ray sources with detections in our Chandra X-ray Visionary Program (XVP), supplemented by 14 addition…
Characterising the surface magnetic fields of T Tauri stars with high-resolution near-infrared spectroscopy
Hussain, G. A. J.; Kochukhov, O.; Lavail, A.
Aims: In this paper, we aim to characterise the surface magnetic fields of a sample of eight T Tauri stars from high-resolution near-infrared spectroscopy. Some stars in our sample are known to be magnetic from previous spectroscopic or spectropolarimetric studies. Our goals are firstly to apply Zeeman broadening modelling to T Tauri stars wi…
Globular cluster candidates in the Galactic bulge: Gaia and VVV view of the latest discoveries
Minniti, D.; Rejkuba, M.; Zoccali, M. +7 more
Context. Thanks to the recent wide-area photometric surveys, the number of star cluster candidates have risen exponentially in the last few years. Most detections, however, are based only on the presence of an overdensity of stars in a given region or an overdensity of variable stars, regardless of their distance. As candidates, their detection ha…