ABSTRACT
On 2023 December 12, the star α Orionis will be occulted by asteroid (319) Leona. This represents an extraordinary and unique opportunity to analyse the brightness distribution of ...Betelgeuse’s photosphere with extreme angular resolution by studying light curves from different points on Earth and at different wavelengths. Here we present observations of another occultation by asteroid Leona, on 2023 September 13, whose goal was to determine Leona’s projected shape and size in preparation for the December 12th event and its interpretation. The occultation campaign was highly successful with 25 positive detections from 17 different sites and a near miss. The effective diameter in projected area derived from the positive detections was 66 ± 2 km using an elliptical fit to the instantaneous limb. The body is highly elongated, with dimensions of 79.6 ± 2.2 km × 54.8 ± 1.3 km in its long and short axis, respectively, at occultation time. This result, in combination with dense time series photometry of Leona that we recently obtained, together with archival sparse photometry, allowed us to predict the angular size of the asteroid for the Betelgeuse event and to simulate the expected brightness change. Also, an accurate position coming from the occultation is provided, to improve the orbit of Leona.
We present time-resolved spectroscopy of the soft X-ray transient XTE J2123–058 in outburst. A useful spectral coverage of 3700–6700 Å was achieved spanning two orbits of the binary, with ...single-epoch coverage extending to ∼9000 Å. The optical spectrum approximates a steep blue power law, consistent with emission on the Rayleigh–Jeans tail of a hot blackbody spectrum. The strongest spectral lines are He ii 4686 Å and C iii/N iii 4640 Å (Bowen blend) in emission. Their relative strengths suggest that XTE J2123–058 was formed in the Galactic plane, not in the halo. Other weak emission lines of He ii and C iv are present, and Balmer lines show a complex structure, blended with He ii. He ii 4686-Å profiles show a complex multiple S-wave structure, with the strongest component appearing at low velocities in the lower-left quadrant of a Doppler tomogram. Hα shows transient absorption between phases 0.35 and 0.55. Both of these effects appear to be analogous to similar behaviour in SW Sex type cataclysmic variables. We therefore consider whether the spectral line behaviour of XTE J2123–058 can be explained by the same models invoked for those systems.
We present a preliminary analysis of visible
+
infrared spectra (0.5–2.4
μm) of 17 asteroids in cometary orbits (ACOs), asteroidal objects with Tisserand parameter
T
<
3. These objects are part of a ...larger database of ACOs observed with the Italian 3.56
m “Telescopio Nazionale Galileo” and the 2.5
m “Nordic Optical Telescope” at the “El Roque de los Muchachos” Observatory (La Palma, Spain). The sample includes 3 near-Earth objects (NEOs), objects with
q
⩽
1.3
AU, and 14 objects non-NEO ACOs (objects with
q
>
1.3
AU). The spectra of the 14 non-NEO ACOs are featureless and no low-level differences are found with respect to normal D-type main belt asteroids. The slope distribution of these objects is also indistinguishable from that of Hilda and Trojan asteroids. Two of the three NEOs in cometary orbits present silicate features typical of S and Q-type asteroids. Considering also that a large fraction (∼30%) of the 16 NEOs in cometary orbits observed by Binzel, R., Rivkin, A. Stuart, J., Harris, A., Bus, S., Burbine, T. Observed spectral properties of near-Earth objects: results for population distribution, source regions, and space weathering processes. Icarus, 170, 259–294, 2004 are S or Q-type, we conclude that this suggests a different origin of the two populations.
The Gravitational Lenses International Time Project (GLITP) collaboration observed the first gravitational lens system (QSO 0957+561) from 2000 February 3 to March 31. The daily VR observations were ...made with the 2.56-m Nordic Optical Telescope at Roque de los Muchachos Observatory, La Palma, Spain. We have derived detailed and robust VR light curves of the two components Q0957+561A and Q0957+561B. In spite of the excellent sampling rate, we have not found evidence in favour of true daily variability. With respect to variability on time-scales of several weeks, we measure VR gradients of about −0.8 mmag d−1 in Q0957+561A and +0.3 mmag d−1 in Q0957+561B. The gradients are very probably originated in the far source. Thus, adopting this reasonable hypothesis (intrinsic variability), we compare them to the expected gradients during the evolution of a compact supernova remnant at the redshift of the source quasar. The starburst scenario is roughly consistent with some former events, but the new gradients do not seem to be caused by supernova remnant activity.
During the last years the number of patients on waiting list for kidney transplantation has been stable. Living donor kidney transplantation is nowadays a chance to increase the pool of donors. ...However, there are a group of patients with ABO incompatibility, making impossible the transplant until now. The aim of the present study is to describe the experience of Hospital Clinic Barcelona on ABO incompatible living transplantation.
A retrospective- descriptive study was made based on 11 living donor kidney recipients with ABO incompatibility in Hospital Clinic of Barcelona from October'06 to January'09. Selective blood group, antibody removal with specific immunoadsortion, immunoglobulin and anti- CD 20 antibody were made until the immunoglobulin (IgG) and isoaglutinine (IgM) antibody titters were 1/8 or lower. Immunosuppressive protocol was adjusted to particular recipient characteristics. Isoaglutinine titters were set before, during and post desensitization treatment and two weeks after transplant. Immunological, medical and surgical evaluation was the standard in living donor kidney transplant program.
Medium age of donors and recipients were 47.8 +/- 12.4 and 44.4 +/- 14.1 years, respectively. 90% of donors were females and 73% of recipients males. Follow-up time was 10.2 +/- 10.2 months. Siblings and spouses were the most frequent relation (n=4, 36.4%, respectively). Chronic glomerulonephritis, adult polycystic kidney disease and Alport syndrome, the most frequent cause of end-stage renal disease. All the patients acquire appropriate isoaglutinine titters pre transplant (< 1/8), requiring 5.54 +/- 2.6 immunoadsorption sessions pretransplant and 2.82 posttransplant. One patient didn t need any immunoadsorption session (incompatibility blood group B) and another patient plasma exchange instead of immunoadsorption for being hypersensitized with positive flow cytometry crossmatch. Posttransplant isoaglutinine titters remained low. Two patients had cellular acute rejection episode (type IA and IB of Banff classification) with good response to corticosteroid treatment. Patient and graft survival were 91% at first year and remain stable during the follow-up. A graft lost by death of patient in relation to haemorrhagic shock developed within the first 72 hours after transplantation. Renal graft function at first year was excellent with serum creatinine of 1.3 +/- 0.8 mg/dl, creatinine clearance of 62.6 ml/min/1.73 m2 and proteinuria of 244.9 mg/U-24h.
ABO incompatible living donor kidney transplantation represent an effective and safe alternative in certain patients on waiting list for renal transplant, obtaining excellent results in patient and graft survival, with good renal graft function.
Faint meteors observed with Super-Schmidt cameras are re-examined in order to assess whether their dynamical and photometric behavior can be described by means of the single body theory. Velocities, ...decelerations and magnitudes are fitted simultaneously to synthetic curves resulting from integration of the appropriate set of differential equations. The parameters determined by this procedure are the ablation coefficient, the shape-density coefficient and the preatmospheric mass of each individual meteoroid. It turns out that 73% of the meteors analyzed here (with magnitudes in the range from +2.5 to -5) are reasonably well described by this theory, suggesting that they did not undergo significant fragmentation during their atmospheric flight. Nevertheless, we identify some systematic differences between observed and theoretical light curves of meteors for which the fit is good. Meteoroid bulk densities are estimated from the retrieved shape-density coefficients. The distributions of individual values are broad, indicating that objects of different densities coexist within the same meteoroid population. The average density is found to be 2400, 1400, and 400 kg m-3 for A-type, B-type and C-type meteoroids, respectively. These results do not confirm the large values determined from quasicontinuous fragmentation models.
From optical R-band data of the double quasar QSO 0957+561A,B, we made two new difference light curves (with an overlap of about 330 d between the time-shifted light curve for the A image and the ...magnitude-shifted light curve for the B image). We observed noisy behaviours around the zero line and no short time-scale events (with a duration of months), where the term ‘event’ refers to a prominent feature that may be a result of microlensing or another source of variability. Only one event lasting two weeks and rising −33 mmag was found. Measured constraints on the possible microlensing variability can be used to obtain information on the granularity of the dark matter in the main lensing galaxy and the size of the source. In addition, one can also test the ability of the observational noise to cause the rms averages and the local features of the difference signals. We focused on this last issue. The combined photometries were related to a process consisting of an intrinsic signal plus a Gaussian observational noise. The intrinsic signal has been assumed to be either a smooth function (polynomial), a smooth function plus a stationary noise process, or a correlated stationary process. Using these three pictures without microlensing, we derived some models totally consistent with the observations. We finally discussed the sensitivity of our telescope (at Teide Observatory) to several classes of microlensing variability.
Measurement of polarized light provides a direct probe of magnetic fields in collimated outflows (jets) of relativistic plasma from accreting stellar-mass black holes at cosmological distances. These ...outflows power brief and intense flashes of prompt gamma-rays known as Gamma Ray Bursts (GRBs), followed by longer-lived afterglow radiation detected across the electromagnetic spectrum. Rapid-response polarimetric observations of newly discovered GRBs have probed the initial afterglow phase. Linear polarization degrees as high as Π∼30% are detected minutes after the end of the prompt GRB emission, consistent with a stable, globally ordered magnetic field permeating the jet at large distances from the central source. In contrast, optical and gamma-ray observations during the prompt phase led to discordant and often controversial results, and no definitive conclusions on the origin of the prompt radiation or the configuration of the magnetic field could be derived. Here we report the detection of linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt gamma-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the GRB jet, closer to the central source, and show that the prompt GRB phase is produced via fast cooling synchrotron radiation in a large-scale magnetic field advected from the central black hole and distorted from dissipation processes within the jet.
•We present MASTER 2230 homogeneous WBVRI+polarization data of microquasar V404 Cyg.•We confirm MASTER polarization variability () and present new episodes.•We discuss the time delays of optical ...flares via X-ray one.
We present several thousands homogeneous photometric (WBVRI and polarization) observations of the microquasar black hole binary V404 Cyg, obtained by the MASTER Global Robotic Network (Lipunov et al. 2010). MASTER were the first telescopes to optically monitor the microquasar after its gamma-ray onset from 18 h 34 m 09 s UT on June 15, 2015 (), until December 31, 2015. We report the results of the analysis of these observations and compare them with the observed X-ray and gamma-ray activity. We confirm the optical emission is correlated with the hard X-ray radiation on timescales of less than 1 min to several hundreds of seconds sec and some anomalously long timescales of up to 25–30 min (). We find no correlation between the delays and the orbital phase. We confirm polarization variability, published earlier (), and present new polarization variability episode.
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