Search results for "eclipsi"

Viaje fantastico del gran piscator de Salamanca : jornadas por vno, y otro mundo, descubrimiento de sus substancias, generaciones, y producciones : C…

Sig. [calderó]8, A-G8 Frontispici amb grav. xil. - Port. orlada. - Reclams

Viaje fantastico del gran piscator de Salamanca : jornadas por vno, y otro mundo, descubrimiento de sus substancias, generaciones, y producciones : C…

1724

Sig. [calderó]8, A-G8 Frontispici amb grav. xil. - Port. orlada. - Reclams

A study of the B and Be star population in the field of the LMC open cluster NGC 2004 with VLT-FLAMES

2005

Observations of hot stars belonging to the young cluster LMC-NGC2004 and its surrounding region have been obtained with the VLT-GIRAFFE facilities in MEDUSA mode. 25 Be stars were discovered; the proportion of Be stars compared to B-type stars is found to be of the same order in the LMC and in the Galaxy fields. 23 hot stars were discovered as spectroscopic binaries (SB1 and SB2), 5 of these are found to be eclipsing systems from the MACHO database, with periods of a few days. About 75% of the spectra in our sample are polluted by hydrogen (Halpha and Hgamma), [SII] and [NII] nebular lines. These lines are typical of HII regions. They could be associated with patchy nebulosities with a bi-m…

Multi-epoch VLTI-PIONIER imaging of the supergiant V766 Cen

2017

Context. The star V766 Cen (=HR 5171A) was originally classified as a yellow hypergiant but lately found to more likely be a 27-36 M red supergiant (RSG). Recent observations indicated a close eclipsing companion in the contact or common-envelope phase. Aims. Here, we aim at imaging observations of V766 Cen to confirm the presence of the close companion. Methods. We used near-infrared H-band aperture synthesis imaging at three epochs in 2014, 2016, and 2017, employing the PIONIER instrument at the Very Large Telescope Interferometer (VLTI). Results. The visibility data indicate a mean Rosseland angular diameter of 4.1 ± 0.8 mas, corresponding to a radius of 1575 ± 400 R. The data show an ex…

Geographicae crucis fabrica et usus

Marca tipogràfica a la portada Signatures: a4, A-G4 Text a dues columnes Escut calcogràfic de l'Abad Carlo Modronio en p. [3]. Caplletres ornades. Mapa gran del món, signat: "Io. Baptista Cauazza excudebat anno 1642," legenda: "Domini est terra et plenitudo eius, Psalmi. Nova totius terrarum orbis Geographica ac hydrographica tabula"

Els viatges de la física: perseguint ombres, mesurant meridians

2013

A partir del segle XVII l’estudi acurat i resolució de diversos problemes de la física, principalment relacionats amb l’astronomia i la forma de la Terra, però no sols, ha passat per realitzar mesures a diferents llocs i, per tant, per l’organització de viatges científics amb aquests objectius específics. Presentarem alguns d’aquests problemes i les solucions adoptades a l’època.

Chandra study of the eclipsing M dwarf binary, YY Gem

2012

The eclipsing M dwarf binary system, YY Gem, was observed using Chandra covering 140 ks (2Prot) in total, split into two even exposures separated by 0.76 d (0.94 Prot). The system was extremely active: three energetic flares were observed over the course of these observations. The flaring and non-flaring states of the system are analysed in this paper. The activity level increased between the first and second observations even during the quiescent (non-flaring) phases. An analysis of the dynamics of the X-ray-emitting plasma suggests that both components are significantly active. Contemporaneous Hα spectra also suggest that both components show similar levels of activity. The primary star i…

A possible solution of the puzzling variation of the orbital period of MXB 1659-298

2017

MXB 1659-298 is a transient neutron star Low-Mass X-ray binary system that shows eclipses with a periodicity of 7.1 hr. The source went to outburst in August 2015 after 14 years of quiescence. We investigate the orbital properties of this source with a baseline of 40 years obtained combining the eight eclipse arrival times present in literature with 51 eclipse arrival times collected during the last two outbursts. A quadratic ephemeris does not fit the delays associated with the eclipse arrival times and the addition of a sinusoidal term with a period of $2.31 \pm 0.02$ yr is required. We infer a binary orbital period of $P=7.1161099(3)$ hr and an orbital period derivative of $\dot{P}=-8.5(…

Reconstruction of an Accretion Disk Image in AU Mon from CoRoT Photometry

2011

AbstractThe long-period binary system AU Mon was photometrically observed on-board the CoRoT satellite in a continuous run of almost 60 days long which has covered almost 5 complete cycles. Unprecedented sub milimag precision of CoRoT photometry reveals all complexity of its light variations in this, still active mass-transfer binary system. We present images of an accretion disk reconstructed by eclipse mapping, and an optimization of intensity distribution along disk surface. Time resolution and accurate CoRoT photometric measurements allow precise location of spatial distribution of ‘hot’ spots on the disk, and tracing temporal changes in their activity. Clumpy disk structure is similar …

X-Ray Eclipse Time Delays in 4U2129+47

2007

4U 2129+47 was discovered in the early 80's and classified as an accretion disk corona source due to its broad and partial X-ray eclipses. The 5.24 hr binary orbital period was inferred from the X-ray and optical light curve modulation, implying a late K or M spectral type companion star. The source entered a low state in 1983, during which the optical modulation disappeared and an F8 IV star was revealed, suggesting that 4U 2129+47 might be part of a triple system. The nature of 4U 2129+47 has since been investigated, but no definitive conclusion has been reached. Here, we present timing and spectral analyses of two XMM-Newton observations of this source, carried out in May and June, 2005.…