Search Publications
The nature of the ASCA/INTEGRAL source AX J183039-1002: a new Compton-thick AGN?
de Rosa, A.; Bird, A. J.; Ubertini, P. +6 more
We report on the identification of the X/soft γ-ray source AX J183039-1002 detected with ASCA and INTEGRAL/IBIS. The source, which has an observed 20-100 keV flux of ~8.6 × 10-11 erg cm-2 s-1, is inside a diffuse radio supernova remnant (SNR) and is spatially coincident with a compact radio source. We analysed arch…
Chandra and XMM-Newton observations of the low-luminosity X-ray pulsators SAX J1324.4-6200 and SAX J1452.8-5949
Paul, Biswajit; Wijnands, Rudy; Degenaar, Nathalie +5 more
We present results from our Chandra and XMM-Newton observations of two low-luminosity X-ray pulsators SAX J1324.4-6200 and SAX J1452.8-5949 which have spin periods of 172 and 437 s, respectively. The XMM-Newton spectra for both sources can be fitted well with a simple power-law model of photon index, Γ ~ 1.0. A blackbody model can equally well fit…
The X-ray properties of the energetic pulsar PSR J1838-0655
Lin, Lupin Chun-Che; Takata, Jumpei; Hwang, Chorng-Yuan +1 more
We present and interpret several new X-ray features of the X-ray pulsar PSR J1838-0655. The X-ray data are obtained from the archival data of Chandra, RXTE and Suzaku. We combine all these X-ray data and fit the spectra with different models. We find that the joint spectra are difficult to fit with a single power law; a broken power-law model with…
Dynamical evolution of Saturn's F ring dust particles
Sfair, R.; Winter, O. C.; Mourão, D. C. +1 more
Saturn's F ring has been the subject of study due to its peculiar structure and the proximity to two satellites, named Prometheus (interior) and Pandora (exterior to the ring), which cause perturbations to the ring particles. Early results from Voyager data have proposed that the ring is populated with centimetre- and micrometre-sized particles. T…
Near-infrared observations of the HE0450-2958 system: discovery of a second active galactic nucleus?
Magain, P.; Chantry, V.; Letawe, G. +1 more
The quasi-stellar object (QSO) HE0450-2958 was brought to the front scene by the non-detection of its host galaxy and strong upper limits on the latter's luminosity. The QSO is also a powerful infrared emitter, in gravitational interaction with a strongly distorted ultraluminous infrared companion galaxy. We investigate the properties of the compa…
A study of B6-9 and A giants
Branham, Richard L., Jr.
To study the kinematics of the B6-9 and A giant stars (luminosity class III), proper motions taken from van Leeuwen's new reduction of the Hipparcos catalogue are used. 36 per cent of the B6-9 stars appear to pertain to the Gould belt, and were excluded from the study. No A star, however, seems to be associated with the Gould belt. 597 B6-9 giants…
On the nature of the near-UV extended light in Seyfert galaxies
Storchi-Bergmann, T.; Schmitt, H. R.; González Delgado, R. M. +4 more
We study the nature of the extended near-UV emission in the inner kiloparsec of a sample of 15 Seyfert (Sy) galaxies which have both near-UV (F330W) and narrow-band [OIII] high-resolution Hubble images. For the majority of the objects, we find a very similar morphology in both bands. From the [OIII] images, we construct synthetic images of the neb…
Near-infrared polarimetry of the Red Rectangle
Witt, A. N.; Gledhill, T. M.; Davis, C. J. +1 more
Imaging polarimetry through J and H broad-band filters and a 3.4 µm narrow-band filter is used to highlight the regions of scattered light in the Red Rectangle. We find that the scattered light identifies the circumbinary dust component of the molecular disc seen in CO emission. This region also appears to be the origin of the recently disco…
Multiwavelength study of M33's giant HII regions NGC 588 and NGC 592
Drissen, Laurent; Úbeda, Leonardo
We present a detailed multiwavelength photometric study of giant HII regions NGC 592 and NGC 588 in the nearby small spiral galaxy M33. We use data taken with the Wide Field and Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope (HST). We detect several massive stars in both ionizing clusters. Six Wolf-Rayet (WR) stars are known to exi…
The VOISE algorithm: a versatile tool for automatic segmentation of astronomical images
Achilleos, N.; Guio, P.
The auroras on Jupiter and Saturn can be studied with a high sensitivity and resolution by the Hubble Space Telescope (HST) ultraviolet (UV) and far-ultraviolet Space Telescope Imaging Spectrograph (STIS) and Advanced Camera for Surveys (ACS) instruments. We present results of automatic detection and segmentation of Jupiter's auroral emissions as …