Search Publications
Timing studies of X Persei and the discovery of its transient quasi-periodic oscillation feature
Serim, M. M.; Şahiner, Ş.; Baykal, A. +3 more
We present a timing analysis of X Persei (X Per) using observations made between 1998 and 2010 with the Proportional Counter Array (PCA) onboard the Rossi X-ray Timing Explorer (RXTE) and with the INTEGRAL Soft Gamma-Ray Imager (ISGRI). All pulse arrival times obtained from the RXTE-PCA observations are phase-connected and a timing solution is obt…
Rummaging inside the Eskimo's parka: variable asymmetric planetary nebula fast wind and a binary nucleus?
Prinja, R. K.; Urbaneja, M. A.
We report on high-resolution optical time series spectroscopy of the central star of the `Eskimo' planetary nebula NGC 2392. Data sets were secured with the European Southern Observatory (ESO) 2.3 m in 2006 March and Canada-France-Hawaii Telescope (CFHT) 3.6 m in 2010 March to diagnose the fast wind and photospheric properties of the central star.…
Ionizing stellar population in the disc of NGC 3310 - II. The Wolf-Rayet population
Pérez-Montero, E.; Sánchez, S. F.; Díaz, A. I. +3 more
We use integral field spectroscopy to study in detail the Wolf-Rayet (WR) population in NGC 3310, spatially resolving 18 star-forming knots with typical sizes of 200-300 pc in the disc of the galaxy hosting a substantial population of WRs. The detected emission in the so-called blue bump is attributed mainly to late-type nitrogen WRs (WNL), rangin…
Validation of optimized population synthesis through mock spectra and Galactic globular clusters
Schiavon, Ricardo P.; Courteau, Stéphane; Roediger, Joel C. +1 more
Optimized population synthesis provides an empirical method to extract the relative mix of stellar evolutionary stages and the distribution of atmospheric parameters within unresolved stellar systems, yet a robust validation of this method is still lacking. We here provide a calibration of population synthesis via non-linear bound-constrained opti…
Molecular line mapping of the giant molecular cloud associated with RCW 106 - IV. Ammonia towards dust emission
Hill, T.; Marshall, J. P.; Urquhart, J. S. +7 more
Here we report observations of the two lowest inversion transitions of ammonia (NH3) with the 70-m Tidbinbilla radio telescope. The aim of the observations is to determine the kinetic temperatures in the dense clumps of the G333 giant molecular cloud associated with RCW 106 and to examine the effect that accurate measures of temperature…
Star-forming galactic contrails as a source of metal enrichment and ionizing radiation at high redshift
Rauch, Michael; Haehnelt, Martin G.; Becker, George D. +1 more
A spectroscopically detected Lyman α emitting halo at redshift 3.216 in the GOODS-N field is found to reside at the convergence of several line-emitting filaments. Spatially extended emission apparently by He II 1640 Å and several metal transitions is seen within several arcseconds from the position of the central galaxy. The V = 24.9 galaxy mainl…
Hubble Space Telescope imaging and spectroscopy of the sirius-like triple star system HD 217411
Bond, Howard E.; Barstow, M. A.; Holberg, J. B. +2 more
We present Hubble Space Telescope imaging and spectroscopy of HD 217411, a G3 V star associated with the extreme ultraviolet (UV) excess source (EUV 2RE J2300-07.0). This star is revealed to be a triple system with a G 3V primary (HD 217411 A) separated by ∼1.1 arcsec from a secondary that is in turn composed of an unresolved K0 V star (HD 21741…
Weighted statistical parameters for irregularly sampled time series
Rimoldini, Lorenzo
Unevenly spaced time series are common in astronomy because of the day-night cycle, weather conditions, dependence on the source position in the sky, allocated telescope time and corrupt measurements, for example, or inherent to the scanning law of satellites like Hipparcos and the forthcoming Gaia. Irregular sampling often causes clumps of measur…
A close examination of cosmic microwave background mirror-parity after Planck
Kovetz, Ely D.; Ben-David, Assaf
Previous claims of significant evidence for mirror-parity in the large-scale cosmic microwave background (CMB) data from the Wilkinson Microwave Anisotropy Probe (WMAP) experiment have been recently echoed in the first study of isotropy and statistics of CMB data from Planck. We revisit these claims with a careful analysis of the latest data avail…
Lyman edges in supermassive black hole binaries.
Generozov, A.; Haiman, Z.
We propose a new spectral signature for supermassive black hole binaries (SMBHBs) with circumbinary gas discs: a sharp drop in flux bluewards of the Lyman limit. A prominent edge is produced if the gas dominating the emission in the Lyman continuum region of the spectrum is sufficiently cold (T ≲ 20 000 K) to contain significant neutral hydrogen. …