We previously identified matrix metalloproteinase 2 (MMP2) and MMP9 plasma levels as candidate biomarkers of bevacizumab activity in patients with recurrent glioblastoma. The aim of this study was to ...assess the predictive value of MMP2 and MMP9 in a randomized phase III trial in patients with newly diagnosed glioblastoma and to explore their tumor source. In this post hoc analysis of the AVAglio trial (AVAGlio/NCT00943826), plasma samples from 577 patients (bevacizumab, n = 283; placebo, n = 294) were analyzed for plasma MMP9 and MMP2 levels by enzyme-linked immunosorbent assay. A prospective local cohort of 38 patients with newly diagnosed glioblastoma was developed for analysis of tumor characteristics by magnetic resonance imaging and measurement of plasma and tumor levels of MMP9 and MMP2. In this AVAglio study, MMP9, but not MMP2, was correlated with bevacizumab efficacy. Patients with low MMP9 derived a significant 5.2-month overall survival (OS) benefit with bevacizumab (HR 0.51, 95% CI 0.34-0.76, p = 0.0009; median 13.6 vs. 18.8 months). In multivariate analysis, a significant interaction was seen between treatment and MMP9 (p = 0.03) for OS. In the local cohort, we showed that preoperative MMP9 plasma levels decreased after tumor resection and were correlated with tumor levels of MMP9 mRNA (p = 0.03). However, plasma MMP9 was not correlated with tumor size, invasive pattern, or angiogenesis. Using immunohistochemistry, we showed that MMP9 was expressed by inflammatory cells but not by tumor cells. After cell sorting, we showed that MMP9 was expressed by CD45+ immune cells. Finally, using flow cytometry, we showed that MMP9 was expressed by tumor-infiltrating neutrophils. In conclusion, circulating MMP9 is predictive of bevacizumab efficacy and is released by tumor-infiltrating neutrophils.
Context. The system of fourplanets discovered around the intermediate-mass star HR8799 offers a unique opportunity to test planet formation theories at large orbital radii and to probe the physics ...and chemistry at play in the atmospheres of self-luminous young (~30 Myr) planets. We recently obtained new photometry of the four planets and low-resolution (R ~ 30) spectra of HR8799 d and e with the SPHERE instrument (Paper III). Aims. In this paper (Paper IV), we aim to use these spectra and available photometry to determine how they compare to known objects, what the planet physical properties are, and how their atmospheres work. Methods. We compare the available spectra, photometry, and spectral energy distribution (SED) of the planets to field dwarfs and young companions. In addition, we use the extinction from corundum, silicate (enstatite and forsterite), or iron grains likely to form in the atmosphere of the planets to try to better understand empirically the peculiarity of their spectrophotometric properties. To conclude, we use three sets of atmospheric models (BT-SETTL14, Cloud-AE60, Exo-REM) to determine which ingredients are critically needed in the models to represent the SED of the objects, and to constrain their atmospheric parameters (Teff, log g, M/H). Results. We find that HR8799d and e properties are well reproduced by those of L6-L8 dusty dwarfs discovered in the field, among which some are candidate members of young nearby associations. No known object reproduces well the properties of planets b and c. Nevertheless, we find that the spectra and WISE photometry of peculiar and/or young early-T dwarfs reddened by submicron grains made of corundum, iron, enstatite, or forsterite successfully reproduce the SED of these planets. Our analysis confirms that only the Exo-REM models with thick clouds fit (within 2σ) the whole set of spectrophotometric datapoints available for HR8799 d and e for Teff = 1200 K, log g in the range 3.0−4.5, and M/H = +0.5. The models still fail to reproduce the SED of HR8799c and b. The determination of the metallicity, log g, and cloud thickness are degenerate. Conclusions. Our empirical analysis and atmospheric modelling show that an enhanced content in dust and decreased CIA of H2 is certainly responsible for the deviation of the properties of the planet with respect to field dwarfs. The analysis suggests in addition that HR8799c and b have later spectral types than the two other planets, and therefore could both have lower masses.
Five new very low mass binaries Montagnier, G.; Ségransan, D.; Beuzit, J.-L. ...
Astronomy and astrophysics (Berlin),
12/2006, Letnik:
460, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We report the discovery of companions to 5 nearby late M dwarfs (>M5), LHS1901, LHS4009, LHS6167, LP869-26 and WT460, and we confirm that the recently discovered mid-T brown dwarf companion to ...SCR1845-6357 is physically bound to that star. These discoveries result from our adaptive optics survey of all M dwarfs within 12 pc. The new companions have spectral types M5 to L1, and orbital separations between 1 and 10 AU. They add significantly to the number of late M dwarfs binaries in the immediate solar neighbourhood, and will improve the multiplicity statistics of late M dwarfs. The expected periods range from 3 to 130 years. Several pairs thus have good potential for accurate mass determination in this poorly sampled mass range.
The SpHere INfrared Exoplanet (SHINE) project is a 500-star survey performed with SPHERE on the Very Large Telescope for the purpose of directly detecting new substellar companions and understanding ...their formation and early evolution. Here we present an initial statistical analysis for a subsample of 150 stars spanning spectral types from B to M that are representative of the full SHINE sample. Our goal is to constrain the frequency of substellar companions with masses between 1 and 75
M
Jup
and semimajor axes between 5 and 300 au. For this purpose, we adopt detection limits as a function of angular separation from the survey data for all stars converted into mass and projected orbital separation using the BEX-COND-hot evolutionary tracks and known distance to each system. Based on the results obtained for each star and on the 13 detections in the sample, we use a Markov chain Monte Carlo tool to compare our observations to two different types of models. The first is a parametric model based on observational constraints, and the second type are numerical models that combine advanced core accretion and gravitational instability planet population synthesis. Using the parametric model, we show that the frequencies of systems with at least one substellar companion are 23.0
−9.7
+13.5
, 5.8
−2.8
+4.7
, and 12.6
−7.1
+12.9
% for BA, FGK, and M stars, respectively. We also demonstrate that a planet-like formation pathway probably dominates the mass range from 1–75
M
Jup
for companions around BA stars, while for M dwarfs, brown dwarf binaries dominate detections. In contrast, a combination of binary star-like and planet-like formation is required to best fit the observations for FGK stars. Using our population model and restricting our sample to FGK stars, we derive a frequency of 5.7
−2.8
+3.8
%, consistent with predictions from the parametric model. More generally, the frequency values that we derive are in excellent agreement with values obtained in previous studies.
Context.
In recent decades, direct imaging has confirmed the existence of substellar companions (exoplanets or brown dwarfs) on wide orbits (>10 au) around their host stars. In striving to understand ...their formation and evolution mechanisms, in 2015 we initiated the SPHERE infrared survey for exoplanets (SHINE), a systematic direct imaging survey of young, nearby stars that is targeted at exploring their demographics.
Aims.
We aim to detect and characterize the population of giant planets and brown dwarfs beyond the snow line around young, nearby stars. Combined with the survey completeness, our observations offer the opportunity to constrain the statistical properties (occurrence, mass and orbital distributions, dependency on the stellar mass) of these young giant planets.
Methods.
In this study, we present the observing and data analysis strategy, the ranking process of the detected candidates, and the survey performances for a subsample of 150 stars that are representative of the full SHINE sample. Observations were conducted in a homogeneous way between February 2015 and February 2017 with the dedicated ground-based VLT/SPHERE instrument equipped with the IFS integral field spectrograph and the IRDIS dual-band imager, covering a spectral range between 0.9 and 2.3 μm. We used coronographic, angular, and spectral differential imaging techniques to achieve the best detection performances for this study, down to the planetary mass regime.
Results.
We processed, in a uniform manner, more than 300 SHINE observations and datasets to assess the survey typical sensitivity as a function of the host star and of the observing conditions. The median detection performance reached 5
σ
-contrasts of 13 mag at 200 mas and 14.2 mag at 800 mas with the IFS (
YJ
and
YJH
bands), and of 11.8 mag at 200 mas, 13.1 mag at 800 mas, and 15.8 mag at 3 as with IRDIS in
H
band, delivering one of the deepest sensitivity surveys thus far for young, nearby stars. A total of sixteen substellar companions were imaged in this first part of SHINE: seven brown dwarf companions and ten planetary-mass companions.These include two new discoveries, HIP 65426 b and HIP 64892 B, but not the planets around PDS70 that had not been originally selected for the SHINE core sample. A total of 1483 candidates were detected, mainly in the large field of view that characterizes IRDIS. The color-magnitude diagrams, low-resolution spectrum (when available with IFS), and follow-up observations enabled us to identify the nature (background contaminant or comoving companion) of about 86% of our subsample. The remaining cases are often connected to crowded-field follow-up observations that were missing. Finally, even though SHINE was not initially designed for disk searches, we imaged twelve circumstellar disks, including three new detections around the HIP 73145, HIP 86598, and HD 106906 systems.
Conclusions.
Nowadays, direct imaging provides a unique opportunity to probe the outer part of exoplanetary systems beyond 10 au to explore planetary architectures, as highlighted by the discoveries of: one new exoplanet, one new brown dwarf companion, and three new debris disks during this early phase of SHINE. It also offers the opportunity to explore and revisit the physical and orbital properties of these young, giant planets and brown dwarf companions (relative position, photometry, and low-resolution spectrum in near-infrared, predicted masses, and contrast in order to search for additional companions). Finally, these results highlight the importance of finalizing the SHINE systematic observation of about 500 young, nearby stars for a full exploration of their outer part to explore the demographics of young giant planets beyond 10 au and to identify the most interesting systems for the next generation of high-contrast imagers on very large and extremely large telescopes.
First light of the VLT planet finder SPHERE Zurlo, A.; Vigan, A.; Galicher, R. ...
Astronomy and astrophysics (Berlin),
03/2016, Letnik:
587, Številka:
A57
Journal Article, Web Resource
Recenzirano
Odprti dostop
Context. The planetary system discovered around the young A-type HR 8799 provides a unique laboratory to: a) test planet formation theories; b) probe the diversity of system architectures at these ...separations, and c) perform comparative (exo)planetology.Aims. We present and exploit new near-infrared images and integral-field spectra of the four gas giants surrounding HR 8799 obtained with SPHERE, the new planet finder instrument at the Very Large Telescope, during the commissioning and science verification phase of the instrument (July–December 2014). With these new data, we contribute to completing the spectral energy distribution (SED) of these bodies in the 1.0–2.5 μm range. We also provide new astrometric data, in particular for planet e, to further constrain the orbits.Methods. We used the infrared dual-band imager and spectrograph (IRDIS) subsystem to obtain pupil-stabilized, dual-band H2H3 (1.593 μm, 1.667 μm), K1K2 (2.110 μm, 2.251 μm), and broadband J (1.245 μm) images of the four planets. IRDIS was operated in parallel with the integral field spectrograph (IFS) of SPHERE to collect low-resolution (R ~ 30), near-infrared (0.94–1.64 μm) spectra of the two innermost planets HR 8799 d and e. The data were reduced with dedicated algorithms, such as the Karhunen-Loève image projection (KLIP), to reveal the planets. We used the so-called negative planets injection technique to extract their photometry, spectra, and measure their positions. We illustrate the astrometric performance of SPHERE through sample orbital fits compatible with SPHERE and literature data.Results. We demonstrated the ability of SPHERE to detect and characterize planets in this kind of systems, providing spectra and photometry of its components. The spectra improve upon the signal-to-noise ratio of previously obtained data and increase the spectral coverage down to the Y band. In addition, we provide the first detection of planet e in the J band. Astrometric positions for planets HR 8799 bcde are reported for the epochs of July, August, and December 2014. We measured the photometric values in J, H2H3, K1K2 bands for the four planets with a mean accuracy of 0.13 mag. We found upper limit constraints on the mass of a possible planet f of 3–7 MJup . Our new measurements are more consistent with the two inner planets d and e being in a 2d:1e or 3d:2e resonance. The spectra of HR 8799 d and e are well matched by those of L6-8 field dwarfs. However, the SEDs of these objects are redder than field L dwarfs longward of 1.6 μm.
Context.
Large surveys with new-generation high-contrast imaging instruments are needed to derive the frequency and properties of exoplanet populations with separations from ~5 to 300 au. A careful ...assessment of the stellar properties is crucial for a proper understanding of when, where, and how frequently planets form, and how they evolve. The sensitivity of detection limits to stellar age makes this a key parameter for direct imaging surveys.
Aims.
We describe the SpHere INfrared survey for Exoplanets (SHINE), the largest direct imaging planet-search campaign initiated at the VLT in 2015 in the context of the SPHERE Guaranteed Time Observations of the SPHERE consortium. In this first paper we present the selection and the properties of the complete sample of stars surveyed with SHINE, focusing on the targets observed during the first phase of the survey (from February 2015 to February 2017). This early sample composed of 150 stars is used to perform a preliminary statistical analysis of the SHINE data, deferred to two companion papers presenting the survey performance, main discoveries, and the preliminary statistical constraints set by SHINE.
Methods.
Based on a large database collecting the stellar properties of all young nearby stars in the solar vicinity (including kinematics, membership to moving groups, isochrones, lithium abundance, rotation, and activity), we selected the original sample of 800 stars that were ranked in order of priority according to their sensitivity for planet detection in direct imaging with SPHERE. The properties of the stars that are part of the early statistical sample wererevisited, including for instance measurements from the
Gaia
Data Release 2. Rotation periods were derived for the vast majority of the late-type objects exploiting TESS light curves and dedicated photometric observations.
Results.
The properties of individual targets and of the sample as a whole are presented.
The system of fourplanets discovered around the intermediate-mass star HR8799 offers a unique opportunity to test planet formation theories at large orbital radii and to probe the physics and ...chemistry at play in the atmospheres of self-luminous young (~30 Myr) planets. In this paper (Paper IV), we aim to use these spectra and available photometry to determine how they compare to known objects, what the planet physical properties are, and how their atmospheres work. We compare the available spectra, photometry, and spectral energy distribution (SED) of the planets to field dwarfs and young companions. Our empirical analysis and atmospheric modelling show that an enhanced content in dust and decreased CIA of H2 is certainly responsible for the deviation of the properties of the planet with respect to field dwarfs. The analysis suggests in addition that HR8799c and b have later spectral types than the two other planets, and therefore could both have lower masses.
We present K, L and M diffraction-limited images of NGC 1068, obtained with NAOS+CONICA at VLT/YEPUN over a $3.5\arcsec \times 3.5\arcsec$ region around the central engine. Hot dust ($T_{\rm col} = ...550{-}650$ K) is found to be distributed in three main structurally different regions: (a) in the true nucleus, seen as a quasi-spherical, however slightly NS elongated, core of extremely hot dust, resolved in K and L with respective diameters of ≈5 pc and 8.5 pc; (b) along the North–South direction, according to a spiral arm like structure and a southern tongue; (c) as a set of parallel elongated nodules (wave-like) on each side, albeit mainly at north, of the jet, at a distance of 50 to 70 pc from the central engine. The IR images reveal several structures also clearly observed on either radio maps, mid-IR or HST UV-visible maps, so that a very precise registration of the respective emissions can be done for the first time from UV to 6 cm. These results do support the current interpretion that source (a) corresponds to emission from dust near sublimation temperature delimiting the walls of the cavity in the central obscuring torus. Structure (b) is thought to be a mixture of hot dust and active star forming regions along a micro spiral structure that could trace the tidal mechanism bringing matter to the central engine. Structure c) which was not known, exhibits too high a temperature for “classical” grains; it is most probably the signature of transiently heated very small dust grains (VSG): nano-diamonds, which are resistant and can form in strong UV field or in shocks, are very attractive candidates. The “waves” can be condensations triggered by jet induced shocks, as predicted by recent models. First estimates, based on a simple VSG model and on a detailed radiative transfer model, do agree with those interpretations, both qualitatively and quantitatively.
Extensive results from the commissioning phase of PUEO, the adaptive optics instrument adaptor for the Canada-France-Hawaii Telescope, are presented and discussed. Analyses of more than 750 images ...recorded with a CCD and a near-IR camera on 16 nights in wavelengths from B to H are used to derive the properties of the compensated wavefront and images in a variety of conditions. The performance characteristics of the system are analyzed and presented in several ways, in terms of delivered Strehl ratios, FWHM, and quantities describing the improvements of both. A qualitative description is given of how the properties of the corrected images result from the structure function of the compensated phase. Under median seeing conditions, PUEO delivers essentially diffraction-limited images at H and K and images with FWHM of about 0.1 arcsec at J and I, and provides significant gains down to B, with guide stars as faint as R = 14. During good conditions, substantial gains were realized with guide stars as faint as R = 17. A simple user interface and software that automatically and continuously optimizes the mode gains during observations makes the operational efficiency extremely high. (Author)
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