40 research outputs found
Direct constraint on the distance of y2 Velorum from AMBER/VLTI observations
In this work, we present the first AMBER observations, of the Wolf-Rayet and
O (WR+O) star binary system y2 Velorum. The AMBER instrument was used with the
telescopes UT2, UT3, and UT4 on baselines ranging from 46m to 85m. It delivered
spectrally dispersed visibilities, as well as differential and closure phases,
with a resolution R = 1500 in the spectral band 1.95-2.17 micron. We interpret
these data in the context of a binary system with unresolved components,
neglecting in a first approximation the wind-wind collision zone flux
contribution. We show that the AMBER observables result primarily from the
contribution of the individual components of the WR+O binary system. We discuss
several interpretations of the residuals, and speculate on the detection of an
additional continuum component, originating from the free-free emission
associated with the wind-wind collision zone (WWCZ), and contributing at most
to the observed K-band flux at the 5% level. The expected absolute separation
and position angle at the time of observations were 5.1±0.9mas and
66±15° respectively. However, we infer a separation of
3.62+0.11-0.30 mas and a position angle of 73+9-11°. Our analysis thus
implies that the binary system lies at a distance of 368+38-13 pc, in agreement
with recent spectrophotometric estimates, but significantly larger than the
Hipparcos value of 258+41-31 pc
Near-Infrared interferometry of Eta Carinae with high spatial and spectral resolution using the VLTI and the AMBER instrument
We present the first NIR spectro-interferometry of the LBV Eta Carinae. The K
band observations were performed with the AMBER instrument of the ESO Very
Large Telescope Interferometer using three 8.2m Unit Telescopes with baselines
from 42 to 89m. The aim of this work is to study the wavelength dependence of
Eta Car's optically thick wind region with a high spatial resolution of 5 mas
(11 AU) and high spectral resolution. The medium spectral resolution
observations (R=1,500) were performed in the wavelength range around both the
HeI 2.059 micron and the Br gamma 2.166 micron emission lines, the high
spectral resolution observations (R=12,000) only in the Br gamma line region.
In the K-band continuum, a diameter of 4.0 +/-0.2 mas (Gaussian FWHM, fit range
28-89m) was measured for Eta Car's optically thick wind region. If we fit
Hillier et al. (2001) model visibilities to the observed AMBER visibilities, we
obtain 50 % encircled-energy diameters of 4.2, 6.5 and 9.6mas in the 2.17
micron continuum, the HeI, and the Br gamma emission lines, respectively. In
the continuum near the Br gamma line, an elongation along a position angle of
120+/-15 degrees was found, consistent with previous VLTI/VINCI measurements by
van Boekel et al. (2003). We compare the measured visibilities with predictions
of the radiative transfer model of Hillier et al. (2001), finding good
agreement. Furthermore, we discuss the detectability of the hypothetical hot
binary companion. For the interpretation of the non-zero differential and
closure phases measured within the Br gamma line, we present a simple geometric
model of an inclined, latitude-dependent wind zone. Our observations support
theoretical models of anisotropic winds from fast-rotating, luminous hot stars
with enhanced high-velocity mass loss near the polar regions.Comment: 22 pages, 14 figures, 2 tables; A&A in pres
Factors of interrupting chemotherapy in patients with Advanced Non-Small-Cell Lung Cancer
<p>Abstract</p> <p>Background</p> <p>Little is known about prognosis of metastatic patients after receiving a first-line treatment and failure. Our group already showed in pre-treated patients enrolled in phase I clinical trials that a performance status (PS) > 2 and an LDH > 600 UI/L were independent prognostic factors. In this prospective study, which included 45 patients, we identified clinical and biological variables as outcome predictors in metastatic Non-Small Cell lung cancer after first line chemotherapy were identified.</p> <p>Findings</p> <p>Forty-five patients that were previously treated for metastatic disease from 12/2000 to 11/2005 in the comprehensive cancer centre (Centre LĂ©on BĂ©rard). Clinical assessment and blood parameters were recorded and considered. Patient prognostic factors for overall survival (OS) with a 0.05-significance level in univariate analysis were entered in a multivariate Cox model for further analysis.</p> <p>Patients' median age was 58.5 years (range: 37 - 76). Sixty two percent of the patients were PS = 0 or 1. After inclusion, nine patients received second-line (22.5%), and two received third-line chemotherapy (5%). Univariate analysis showed that the factors associated with reduced OS were: PS > 2, weight loss >10%, more than one line of chemotherapy treatment and abnormal blood parameters (hemoglobin (Hb), platelet and neutrophils counts). Multiple regression analysis confirmed that PS > 2 and abnormal hemoglobin were independent predictors for low overall survival. According to the presence of none (33%), 1 (37%) and 2 (30%) prognostic factors, median OS were 12, 5 and 2 months respectively.</p> <p>Conclusion</p> <p>From this prospective study, both PS and anemia were found as independent determinants of survival, we found that both PS and anemia were independent determinants of survival. The combination of poor PS and anemia is an effective strategy to predict survival in the case of patients with metastatic NSCLC receiving further treatment after the first line.</p
Tolerability of gefitinib in patients receiving treatment in everyday clinical practice
Gefitinib (âIressaâ, ZD1839), an epidermal growth factor receptor tyrosine kinase inhibitor, has recently been approved in several countries for use in advanced or metastatic non-small-cell lung cancer (NSCLC). In contrast to chemotherapies, which are generally used at or near their maximum-tolerated dose (MTD), gefitinib is used at an optimal biological dose (250âmgâdayâ1), which is substantially below its MTD, minimising the risk of adverse events without compromising efficacy. Tolerability data from the compassionate use of gefitinib in the âIressaâ Expanded Access Programme support the favourable safety profile of the agent reported in Phase I and II trials. In both settings, the majority of adverse drug reactions were mild/moderate and consisted mainly of grade 1/2 diarrhoea and skin rash. Although skin rash has been suggested to predict response to gefitinib, available data do not support this hypothesis. Overall, these tolerability data demonstrate that gefitinib has a relatively benign side-effect profile and is a well-tolerated treatment option for patients with previously treated NCSLC, who currently have few alternatives
A phase I/II study of 4 monthly courses of high-dose cyclophosphamide and thiotepa for metastatic breast cancer patients
This pilot phase I/II study intended to determine the maximum tolerated dose of cyclophosphamide and thiotepa administered on four consecutive courses with peripheral blood progenitor cell and granulocyte-colony stimulating factor support, as first-line therapy for hormone-refractory metastatic breast cancer patients. Twenty-eight patients were entered in the study. After two courses of epirubicin (120âmgâmâ2) and cyclophosphamide (2âg mâ2) followed by granulocyte-colony stimulating factor injection and leukaphereses, patients received four cycles of cyclophosphamide and thiotepa. Each cycle was followed by peripheral blood progenitor cell and granulocyte-colony stimulating factor supports, then repeated every 28 to 35 days. Six escalating dose levels of cyclophosphamide and thiotepa were planned, beginning at cyclophosphamide 1.5âg mâ2 and thiotepa 200âmgâmâ2. At least three patients were enrolled for each dose level. Eighteen patients completed the study. The maximum tolerated dose was 3000âmgâmâ2 cyclophosphamide and 400âmgâmâ2 thiotepa per course. Haematological toxicity was manageable on an outpatient basis and did not increase significantly with dose escalation. Dose-limiting toxicity was chemotherapy-induced immuno-suppression, which resulted in one toxic death and two life-threatening infections. Median times to treatment failure and survival were 11 and 26 months, respectively. Three patients were alive, free of disease 30 months after completion of the study. Such therapy allows for high-dose intensity and high cumulative doses on a short period of time with manageable toxicity
Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD 104237
This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record.Aims. We investigate the origin of the BrÎł emission of the Herbig Ae star HD 104237 on Astronomical Unit (AU) scales.
Methods. Using AMBER/VLTI at a spectral resolution R = 1500 we spatially resolve the emission in both the BrÎł line and the adjacent continuum.
Results. The visibility does not vary between the continuum and the BrÎł line, even though the line is strongly detected in the spectrum, with a peak
intensity 35% above the continuum. This demonstrates that the line and continuum emission have similar size scales. We assume that the K-band
continuum excess originates in a âpuffed-upâ inner rim of the circumstellar disk, and discuss the likely origin of BrÎł.
Conclusions. We conclude that this emission most likely arises from a compact disk wind, launched from a region 0.2â0.5 AU from the star, with
a spatial extent similar to that of the near infrared continuum emission region, i.e., very close to the inner rim location.This work has been partly supported by the
MIUR COFIN grant 2003/027003-001 and 025227/2004 to the INAFOsservatorio
Astrofisico di Arcetri. This project has benefited from
funding from the French Centre National de la Recherche Scientifique
(CNRS) through the Institut National des Sciences de lâUnivers
(INSU) and its Programmes Nationaux (ASHRA, PNPS). The authors
from the French laboratories would like to thank the successive
directors of the INSU/CNRS directors. C. Gil work was supported
in part by the FundacžËao para a CiËencia e a Tecnologia through
project POCTI/CTE-AST/55691/2004 from POCTI,with funds from
the European program FEDER
Interferometric data reduction with AMBER/VLTI. Principle, estimators, and illustration
This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record.Aims. In this paper, we present an innovative data reduction method for single-mode interferometry. It has been specifically developed for the
AMBER instrument, the three-beam combiner of the Very Large Telescope Interferometer, but it can be derived for any single-mode interferometer.
Methods. The algorithm is based on a direct modelling of the fringes in the detector plane. As such, it requires a preliminary calibration of the
instrument in order to obtain the calibration matrix that builds the linear relationship between the interferogram and the interferometric observable,
which is the complex visibility. Once the calibration procedure has been performed, the signal processing appears to be a classical least-square
determination of a linear inverse problem. From the estimated complex visibility, we derive the squared visibility, the closure phase, and the
spectral differential phase.
Results. The data reduction procedures have been gathered into the so-called amdlib software, now available for the community, and are presented
in this paper. Furthermore, each step in this original algorithm is illustrated and discussed from various on-sky observations conducted with the
VLTI, with a focus on the control of the data quality and the effective execution of the data reduction procedures. We point out the present limited
performances of the instrument due to VLTI instrumental vibrations which are difficult to calibrate.The AMBER project4 was founded by the French Centre
National de la Recherche Scientifique (CNRS), the Max Planck Institute fĂŒr
Radioastronomie (MPIfR) in Bonn, the Osservatorio Astrofisico di Arcetri
(OAA) in Firenze, the French Region âProvence Alpes CĂŽte DâAzurâ and
the European Southern Observatory (ESO). The CNRS funding has been
made through the Institut National des Sciences de lâUnivers (INSU) and its
Programmes Nationaux (ASHRA, PNPS, PNP).
The OAA co-authors acknowledge partial support from MIUR grants to the
Arcetri Observatory: A LBT interferometric arm, and analysis of VLTI interferometric
data and From Stars to Planets: accretion, disk evolution and
planet formation and from INAF grants to the Arcetri Observatory Stellar and
Extragalactic Astrophysics with Optical Interferometry. C. Gil work was supported
in part by the Fundação para a CiĂȘncia e a Tecnologia through project
POCTI/CTE-AST/55691/2004 from POCTI, with funds from the European program
FEDER
Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD 104237
Astronomy and Astrophysics, 464, pp. 55-58, http://dx.doi.org./10.1051/0004-6361:20065719International audienc
An asymmetry detected in the disk of Kappa CMa with the AMBER/VLTI
International audienceAims. We study the geometry and kinematics of the circumstellar environment of the Be star Kappa CMa in the Br gamma emission line and its nearby continuum. Methods. We use the VLTI/AMBER instrument operating in the K band which provides a spatial resolution of about 6 mas with a spectral resolution of 1500 to study the kinematics within the disk and to infer its rotation law. In order to obtain more kinematical constraints we also use an high spectral resolution Pa beta line profile obtain in December 2005 at the Observatorio do Pico do Dios, Brazil and we compile V/R line profile variations and spectral energy distribution data points from the literature. Results. Using differential visibilities and differential phases across the Br gamma line we detect an asymmetry in the disk. Moreover, we found that kappa CMa seems difficult to fit within the classical scenario for Be stars, illustrated recently by alpha Arae observations, i.e. a fast rotating B star close to its breakup velocity surrounded by a Keplerian circumstellar disk with an enhanced polar wind. Finally we discuss the possibility for kappa CMa to be a critical rotator with a Keplerian rotating disk and try to see if the detected asymmetry can be interpreted within the "one-armed" viscous disk framework
Disk and wind interaction in the young stellar object MWC 297 spatially resolved with AMBER/VLTI
This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record.The young stellar object MWC 297 is an embedded B1.5Ve star exhibiting strong hydrogen emission lines and a strong near-infrared continuum
excess. This object has been observed with the VLT interferometer equipped with the AMBER instrument during its first commissioning run.
AMBER/VLTI is currently the only near infrared interferometer that can observe spectrally dispersed visibilities. MWC 297 has been spatially
resolved in the continuum with a visibility of 0.50+0.08
â0.10 as well as in the BrÎł emission line where the visibility decreases to 0.33±0.06. This change
in the visibility with wavelength can be interpreted by the presence of an optically thick disk responsible for the visibility in the continuum and
of a stellar wind traced by the BrÎł emission line and whose apparent size is 40% larger. We validate this interpretation by building a model of the
stellar environment that combines a geometrically thin, optically thick accretion disk model consisting of gas and dust, and a latitude-dependent
stellar wind outflowing above the disk surface. The continuum emission and visibilities obtained from this model are fully consistent with the
interferometric AMBER data. They agree also with existing optical, near-infrared spectra and other broad-band near-infrared interferometric
visibilities. We also reproduce the shape of the visibilities in the BrÎł line as well as the profile of this line obtained at an higher spectral resolution
with the VLT/ISAAC spectrograph, and those of the Hα and HÎČ lines. The disk and wind models yield a consistent inclination of the system of
approximately 20âŠ. A picture emerges in which MWC 297 is surrounded by an equatorial flat disk that is possibly still accreting and an outflowing
wind that has a much higher velocity in the polar region than at the equator. The AMBER/VLTI unique capability of measuring spectral visibilities
therefore allows us for the first time to compare the apparent geometry of a wind with the disk structure in a young stellar system.The AMBER project4 was founded by the French Centre National de la
Recherche Scientifique (CNRS), the Max Planck Institute fĂŒr Radioastronomie
(MPIfR) in Bonn, the Osservatorio Astrofisico di Arcetri (OAA) in Firenze,
the French Region "Provence Alpes CĂŽte DâAzur" and the European Southern
Observatory (ESO). The CNRS funding has been made through the Institut
National des Sciences de lâUnivers (INSU) and its Programmes Nationaux
(ASHRA, PNPS, PNP).
The OAA co-authors acknowledge partial support from MIUR grants to
the Arcetri Observatory: A LBT interferometric arm, and analysis of VLTI interferometric
data and From Stars to Planets: accretion, disk evolution and
planet formation and from INAF grants to the Arcetri Observatory Stellar and
Extragalactic Astrophysics with Optical Interferometry. C. Gil work was supported
in part by the Fundação para a CiĂȘncia e a Tecnologia through project
POCTI/CTE-AST/55691/2004 from POCTI, with funds from the European program
FEDER