Search Publications

Constraining the Fundamental Parameters of the O-Type Binary CPD -41 7733

Gosset, E.; Rauw, G.; Sana, H.

Using a set of high-resolution spectra, we studied the physical and orbital properties of the O-type binary CPD -41 7733, located in the core of NGC 6231. We report the unambiguous detection of a secondary spectral signature and we derive the first SB2 orbital solution of the system. The period is 5.6815+/-0.0015 days, and the orbit has no signifi…

Solar Cycle Variation of Real CME Latitudes

Feng, Xueshang; Song, Wenbin; Hu, Yanqi

With the assumption of radial motion and uniform longitudinal distribution of coronal mass ejections (CMEs), we propose a method to eliminate projection effects from the apparent observed CME latitude distribution. This method has been applied to SOHO LASCO data from 1996 January to 2006 December. As a result, we find that the real CME latitude di…

Photometric study of the W UMa eclipsing binaries VW LMi and BX Dra

García-Melendo, E.; Gómez-Forrellad, J. M.; Sánchez-Bajo, F.

New ephemeris and the absolute parameters—masses, radii and luminosities—of the contact systems VW LMi and BX Dra have been obtained, by means of the analysis of the minima data available in the literature (for the determination of the ephemeris) and combining the previously published spectroscopic information and the results of the Wilson-Devinne…

New Ultraviolet Observations of AM CVn

Eracleous, Michael; Wade, Richard A.; Flohic, Hélène M. L. G.

We have obtained observations of the ultraviolet spectrum of AM CVn, an ultrashort-period helium cataclysmic variable, using the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope (HST). We obtained data in time-tag mode during two consecutive orbits of HST, covering 1600-3150 and 1140-1710 Å, respectively. The mean spectrum is…

A catalogue of candidate Red Clump stars in the Tycho-2.

Rybka, S. P.

Strands and braids in narrow planetary rings: a scattering system approach

Merlo, Olivier; Benet, Luis

We address the occurrence of narrow planetary rings and some of their structural properties, in particular when the rings are shepherded. We consider the problem as Hamiltonian scattering of a large number of non-interacting massless point particles in an effective potential. Using the existence of stable motion in scattering regions in this set u…

Super Star Cluster NGC 1705-1: A Local Analog to the Birth Site of Long-Duration γ-Ray Bursts

Chen, Hsiao-Wen; Bloom, Joshua S.; Prochaska, Jason X.

Recent observations suggest that global properties of the host galaxies for long-duration γ-ray bursts (GRBs) are particularly well suited for creating the massive star progenitors of these GRBs. Motivated by the hypothesis that massive young star clusters located in metal-poor, low-metallicity galaxies are a natural birth site for GRB progenitors…

Cygnus X-3 transition from the ultrasoft to the hard state

Gehrels, N.; von Kienlin, A.; De Cesare, G. +8 more

Aims:The nature of Cygnus X-3 is still not understood well. This binary system might host a black hole or a neutron star. Recent observations by INTEGRAL have shown that Cygnus X-3 was again in an extremely ultrasoft state. Here we present our analysis of the transition from the ultrasoft state, dominated by blackbody radiation at soft X-rays plus…

Multimode Pulsations of the λ Bootis Star 29 Cygni: The 1995 and 1996 Multisite Campaigns

Handler, G.; Krisciunas, K.; Paunzen, E. +19 more

In this paper we present the results of multisite photometric and spectroscopic campaigns, carried out during the years 1995 and 1996, to study the pulsations of a typical λ Bootis star, 29 Cyg. During the 1995 campaign we found well-defined multiperiodicity in 29 Cyg, which was studied in detail during a multilongitude campaign covering a 65 day …

INTEGRAL observations of TeV plerions

Santangelo, A.; Horns, D.; Hoffmann, A. I. D.

Amongst the sources seen in very high gamma-rays several are associated with Pulsar Wind Nebulae ("TeV plerions"). The study of hard X-ray/soft gamma-ray emission is providing an important insight into the energetic particle population present in these objects. The unpulsed emission from pulsar/pulsar wind nebula systems in the energy range access…