Search Publications

CCD astrometric observations of Phoebe in 2003-2004

Qiao, R. C.; Yu, Y.; Shen, K. X. +5 more

In 2003-2004, we obtained 115 new observations of Phoebe, the 9th Saturnian faint satellite (visual magnitude of about 16.5). We used a large CCD detector (2048×2048 pixels) mounted on the 1.56 m astrometric reflector at the Sheshan Station, near Shanghai. In our reduction, an up-to-date catalogue of stars, UCAC2 (Zacharias et al. 2004), was chose…

The ultra-compact binary 4U 1850-087 observed with INTEGRAL: hard X-ray emission from an X-ray burster

Mereghetti, S.; Sidoli, L.; Bazzano, A. +1 more

Context: .The X-ray burster 4U 1850-087, located in the Galactic globular cluster NGC 6712, is an ultracompact binary (orbital period ~21 min), likely harbouring a degenerate companion.
Aims: .The source has been observed at soft γ-rays several times with the INTEGRAL satellite, during the monitoring of the Galactic plane, with an unprecedente…

Slow halo CMEs with shock signatures

Pohjolainen, S.; Lehtinen, N. J.

Context: .In the solar corona, shocks are formed when the speed of a disturbance exceeds the local magnetosonic speed. In the active region corona the Alfvén speed can drop to a few hundred km s^-1, but globally it is much higher. There has been a long debate on whether the shocks responsible for type II bursts are created by bow shocks …

GRB 030406 - an extremely hard burst outside of the INTEGRAL field of view

Goldoni, P.; Rau, A.; Bulik, T. +3 more

Using the IBIS Compton mode, the INTEGRAL satellite is able to detect and localize bright and hard GRBs, which happen outside of the nominal INTEGRAL field of view. We have developed a method of analyzing such INTEGRAL data to obtain the burst location and spectra. We present the results for the case of GRB 030406. The burst is …

Low mass pre-main sequence stars in the Large Magellanic Cloud

Panagia, N.; Romaniello, M.; Blanco, C. +2 more

As a part of an ongoing effort to characterise the young stellar populations in the Large Magellanic Cloud, we present HST-WFPC2 broad and narrow band imaging of two fields with recent star formation activity in the Tarantula region. A population of objects with Hα and/or Balmer continuum excess was identified. On account of the intense Hα emissio…

Macrospicules and blinkers as seen in Shutterless EIT 304 Å

Doyle, J. G.; Madjarska, M. S.; Hochedez, J. -F. +1 more

Aims.Small-scale transient phenomena in the solar atmosphere are believed to play a crucial role in the coronal heating and solar wind generation. This study aims at providing new observational evidence on blinkers and macrospicules appearance in imager data and in doing so, establish the long disputed relationship between these phenomena.
Met…

Effervescent heating: constraints from nearby cooling flow clusters observed with XMM-Newton

Kaastra, J. S.; Piffaretti, R.

Aims.We have used deprojected radial density and temperature profiles of a sample of 16 nearby CF clusters observed with XMM-Newton to test whether the effervescent heating model can satisfactorily explain the dynamics of CF clusters.
Methods.For each cluster we derived the required extra heating as a function of cluster-centric distance for va…

The weak INTEGRAL bursts GRB 040223 and GRB 040624: an emerging population of dark afterglows

Covino, S.; D'Avanzo, P.; Campana, S. +18 more

We report here γ-ray, X-ray and near-infrared observations of GRB 040223 along with γ-ray and optical observations of GRB 040624. GRB 040223 was detected by INTEGRAL close to the Galactic plane and GRB 040624 at high Galactic latitude. Analyses of the prompt emission detec…

Short-term changes in the belt/zone structure of Saturn's Southern Hemisphere (1996-2004)

Sánchez-Lavega, A.; Pérez-Hoyos, S.; French, R. G.

Aims.The main goal of this paper is to study the reflectivity changes that affect Saturn's global belt/zone pattern on time-scales from weeks to a few months, and to determine their frequency and intensity, as well as the variations of the vertical cloud structure that cause such changes.
Methods: .We have used 177 images from Hubble Space Tel…

The dark clump near Abell 1942: dark matter halo or statistical fluke?

Castander, F. J.; von der Linden, A.; Schneider, P. +1 more

Using HST WFPC2 mosaic imaging, deep Chandra observations, and the

original CFHT imaging, we investigate the case for the dark clump candidate originally presented by (Erben et al. 2000, A&A, 355, 23). We show that the original detection is well reproducible in the CFHT data, and can confirm the presence of an alignment signal at the dark…