Isolated Pulmonary Valve Endocarditis.

Infective endocarditis involving the right side of the heart is typically associated with IV drug abuse and chronic indwelling catheters which commonly involve the tricuspid valve. Isolated pulmonary valve endocarditis (PVE) is a rare clinical entity. We report a rare case of a young woman with a history of end-stage renal disease (ESRD) on hemodialysis through tunneled catheter presenting with persistent coagulase-negative staphylococcus (CoNS) epidermidis bacteremia despite being on appropriate treatment with IV vancomycin for two weeks. Because of the persistent bacteremia, a transesophageal echocardiogram was performed and it revealed a thickened pulmonary valve with 1.8 cm vegetation in the left posterior cusp. She was successfully treated with IV daptomycin course for a total of six weeks. The recommended management for PVE is usually medical treatment with IV antibiotics gauged according to sensitivities of the cultures. Our article highlights the fact that the decision to manage it medically versus surgically can propose a challenge as the guidelines are not very robust

Modeling the e-APD SAPHIRA/C-RED ONE camera at low flux level: An attempt to count photons in the near-infrared with the MIRC-X interferometric combiner

This is the final version. Available on open access from EDP Sciences via the DOI in this recordContext. We implement an electron avalanche photodiode (e-APD) in the MIRC-X instrument, upgrade of the 6-telescope nearinfrared imager MIRC, at the CHARA array. This technology should improve the sensitivity of near-infrared interferometry. Aims. We characterize a near-infrared C-RED ONE camera from First Light Imaging (FLI) using an e-APD from Leonardo (previously SELEX). Methods. We first used the classical Mean-Variance analysis to measure the system gain and the amplification gain. We then developed a physical model of the statistical distribution of the camera output signal. This model is based on multiple convolutions of the Poisson statistic, the intrinsic avalanche gain distribution, and the observed distribution of the background signal. At low flux level, this model constraints independently the incident illumination level, the total gain, and the excess noise factor of the amplification. Results. We measure a total transmission of 48 ± 3% including the cold filter and the Quantum Efficiency. We measure a system gain of 0.49 ADU/e, a readout noise of 10 ADU, and amplification gains as high as 200. These results are consistent between the two methods and therefore validate our modeling approach. The measured excess noise factor based on the modeling is 1.47 ± 0.03, with no obvious dependency with flux level or amplification gain. Conclusions. The presented model allows measuring the characteristics of the e-APD array at low flux level independently of preexisting calibration. With < 0.3 electron equivalent readout noise at kilohertz frame rates, we confirm the revolutionary performances of the camera with respect to the PICNIC or HAWAII technologies. However, the measured excess noise factor is significantly higher than the one claimed in the literature (<1.25), and explains why counting multiple photons remains challenging with this camera.European Union Horizon 2020Labex OSUG@2020CNRS/INS

MYSTIC: Michigan Young STar Imager at CHARA

This is the final version of the article. Available from SPIE via the DOI in this record.We present the design for MYSTIC, the Michigan Young STar Imager at CHARA. MYSTIC will be a K-band, cryogenic, 6-beam combiner for the Georgia State University CHARA telescope array. The design follows the image-plane combination scheme of the MIRC instrument where single-mode fibers bring starlight into a non-redundant fringe pattern to feed a spectrograph. Beams will be injected in polarization-maintaining fibers outside the cryogenic dewar and then be transported through a vacuum feedthrough into the ~220K cold volume where combination is achieved and the light is dispersed. We will use a C-RED One camera (First Light Imaging) based on the eAPD SAPHIRA detector to allow for near-photon-counting performance. We also intend to support a 4-telescope mode using a leftover integrated optics component designed for the VLTI-GRAVITY experiment, allowing better sensitivity for the faintest targets. Our primary science driver motivation is to image disks around young stars in order to better understand planet formation and how forming planets might influence disk structures.MYSTIC is funded by the USA National Science Foundation (PI: Monnier, NSF-ATI 1506540) while the MIRC-X project is funded by the European Research Council (PI: Kraus, ERC, Grant # 639889)

The MIRC-X 6-telescope imager: Key science drivers, instrument design and operation

This is the final version of the article. Available from SPIE via the DOI in this recordMIRC-X is a new beam combination instrument at the CHARA array that enables 6-telescope interferometric imaging on object classes that until now have been out of reach for milliarcsecond-resolution imaging. As part of an instrumentation effort lead by the University of Exeter and University of Michigan, we equipped the MIRC instrument with an ultra-low read-noise detector system and extended the wavelength range to the J and H-band. The first phase of the MIRC-X commissioning was successfully completed in June 2017. In 2018 we will commission polarisation control to improve the visibility calibration and implement a 'cross-talk resiliant' mode that will minimise visibility cross-talk and enable exoplanet searches using precision closure phases. Here we outline our key science drivers and give an overview about our commissioning timeline. We comment on operational aspects, such as remote observing, and the prospects of co-phased parallel operations with the upcoming MYSTIC combiner.MIRC-X is funded by a Starting Grant from the European Research Council (ERC; grant agreement No. 639889, PI: Kraus) and funds from the University of Exeter. The project builds on earlier investments from the University of Michigan and the National Science Foundation (NSF, PI: Monnier)

MIRC-X/CHARA: sensitivity improvements with an ultra-low noise SAPHIRA detector

This is the final version of the article. Available from Society of Photo Optical Instrumentation Engineers (SPIE) via the DOI in this record.MIRC-X is an upgrade of the six-telescope infrared beam combiner at the CHARA telescope array, the world's largest baseline interferometer in the optical/infrared, located at the Mount Wilson Observatory in Los Angeles. The upgraded instrument features an ultra-low noise and fast frame rate infrared camera (SAPHIRA detector) based on e-APD technology. We report the MIRC-X sensitivity upgrade work and first light results in detail focusing on the detector characteristics and software architecture.MIRC-X is funded, in parts, by a Starting Grant from the European Research Council (ERC; grant agreement No. 639889, PI: Kraus) and builds on earlier investments from the University of Michigan and the National Science Foundation (NSF, PI: Monnier). This research has made use of the Jean-Marie Mariotti Center OIFits Explorer service (http://www.jmmc.fr/oifitsexplorer)

A high-mass protobinary system with spatially resolved circumstellar accretion disks and circumbinary disk

This is the author accepted manuscript. The final version is available from American Astronomical Society via the DOI in this record.High-mass multiples might form via fragmentation of self-gravitational disks or alternative scenarios such as disk-assisted capture. However, only few observational constraints exist on the architecture and disk structure of high-mass protobinaries and their accretion properties. Here we report the discovery of a close (57.9 ± 0.2mas=170au) high-mass protobinary, IRAS17216-3801, where our VLTI/GRAVITY+AMBER near-infrared interferometry allows us to image the circumstellar disks around the individual components with 3milliarcsecond resolution. We estimate the component masses to 20 and 18M⊙ and find that the radial intensity profiles can be reproduced with an irradiated disk model, where the inner regions are excavated of dust, likely tracing the dust sublimation region in these disks. The circumstellar disks are strongly misaligned with respect to the binary separation vector, which indicates that the tidal forces did not have time to realign the disks, pointing towards a young dynamical age of the system. We constrain the distribution of the Br and CO-emitting gas using VLTI/GRAVITY spectro-interferometry and VLT/CRIRES spectro-astrometry and find that the secondary is accreting at a higher rate than the primary. VLT/NACO imaging shows L′-band emission on 3 − 4× larger scales than the binary separation, matching the expected dynamical truncation radius for the circumbinary disk. The IRAS17216-3801 system is 3× more massive and 5× more compact than other high-mass multiplies imaged at infrared wavelengths and the first high-mass protobinary system where circumstellar and circumbinary dust disks could be spatially resolved. This opens exciting new opportunities for studying star-disk interactions and the role of multiplicity in high-mass star formation.We thank the GRAVITY consortium and the Science Verification team, which is composed of ESO employees and GRAVITY consortium members (https://www.eso.org/sci/activities/vltsv/gravitysv.html). We acknowledge support from an STFC Rutherford fellowship/grant (ST/J004030/1, ST/K003445/1), Marie Sklodowska-Curie CIG grant (#618910), Philip Leverhulme prize (PLP-2013-110), and ERC Starting grant (Grant Agreement #639889)

The GRAVITY instrument software / High-level software

GRAVITY is the four-beam, near- infrared, AO-assisted, fringe tracking, astrometric and imaging instrument for the Very Large Telescope Interferometer (VLTI). It is requiring the development of one of the most complex instrument software systems ever built for an ESO instrument. Apart from its many interfaces and interdependencies, one of the most challenging aspects is the overall performance and stability of this complex system. The three infrared detectors and the fast reflective memory network (RMN) recorder contribute a total data rate of up to 20 MiB/s accumulating to a maximum of 250 GiB of data per night. The detectors, the two instrument Local Control Units (LCUs) as well as the five LCUs running applications under TAC (Tools for Advanced Control) architecture, are interconnected with fast Ethernet, RMN fibers and dedicated fiber connections as well as signals for the time synchronization. Here we give a simplified overview of all subsystems of GRAVITY and their interfaces and discuss two examples of high-level applications during observations: the acquisition procedure and the gathering and merging of data to the final FITS file.Comment: 8 pages, 7 figures, published in Proc. SPIE 9146, Optical and Infrared Interferometry IV, 91462

MIRC-X polarinterferometry at CHARA

This is the final version. Available from SPIE via the DOI in this recordSPIE Astronomical Telescopes + Instrumentation conference, 14 - 18 December 2020, Online OnlyWe present a new polarimetric mode for the MIRC-X 6-telescope beam combiner at CHARA. Utilizing the extensive u - v coverage afforded by CHARA this mode will be able to resolve and constrain scattered light in environs at milliarcsecond separations of target stars, a largely unexplored parameter space to-date in astronomy. Notably, this upgrade will allow for the investigation of the scattering properties of the inner dust wall at the sublimation radius of Herbig Ae/Be star disks, dust shells surrounding evolved stars, and gas-rich disks around Be stars. Our design adds a series of rotating half-wave plates, achromatic across J- and H-bands, and a polarizing beamsplitter into the MIRC-X beam path. In this work, we also preview on-sky observations, discussing ongoing work calibrating instrumental polarization effects in the CHARA beam path as well as upgrades to the MIRC-X data reduction pipeline.NASANational Science Foundation (NSF

First direct detection of an exoplanet by optical interferometry; Astrometry and K-band spectroscopy of HR8799 e

To date, infrared interferometry at best achieved contrast ratios of a few times $10^{-4}$ on bright targets. GRAVITY, with its dual-field mode, is now capable of high contrast observations, enabling the direct observation of exoplanets. We demonstrate the technique on HR8799, a young planetary system composed of four known giant exoplanets. We used the GRAVITY fringe tracker to lock the fringes on the central star, and integrated off-axis on the HR8799e planet situated at 390 mas from the star. Data reduction included post-processing to remove the flux leaking from the central star and to extract the coherent flux of the planet. The inferred K band spectrum of the planet has a spectral resolution of 500. We also derive the astrometric position of the planet relative to the star with a precision on the order of 100$\,\mu$as. The GRAVITY astrometric measurement disfavors perfectly coplanar stable orbital solutions. A small adjustment of a few degrees to the orbital inclination of HR 8799 e can resolve the tension, implying that the orbits are close to, but not strictly coplanar. The spectrum, with a signal-to-noise ratio of $\approx 5$ per spectral channel, is compatible with a late-type L brown dwarf. Using Exo-REM synthetic spectra, we derive a temperature of $1150\pm50$\,K and a surface gravity of $10^{4.3\pm0.3}\,$cm/s$^{2}$. This corresponds to a radius of $1.17^{+0.13}_{-0.11}\,R_{\rm Jup}$ and a mass of $10^{+7}_{-4}\,M_{\rm Jup}$, which is an independent confirmation of mass estimates from evolutionary models. Our results demonstrate the power of interferometry for the direct detection and spectroscopic study of exoplanets at close angular separations from their stars.Comment: published in A&

Dynamical masses of the primary Be star and the secondary sdB star in the single-lined binary kappa Dra (B6 IIIe)

Because many classical Be stars may owe their nature to mass and angular-momentum transfer in a close binary, the present masses, temperatures, and radii of their components are of high interest for comparison to stellar evolution models. Kappa Dra is a 61.5-day single-lined binary with a B6 IIIe primary. With the CHARA Array instruments MIRC/MIRC-X and MYSTIC, we detected the secondary at (approximately photospheric) flux ratios of 1.49 +- 0.10% and 1.63 +- 0.09% in the H and K band, respectively. From a large and diverse optical spectroscopic database only the radial velocity curve of the Be star could be extracted. However, employing the parallaxes from Hipparcos and Gaia, which agree within their nominal 1-sigma errors, we could derive the total mass and found component masses of 3.65 +- 0.48 Msun and 0.426 +- 0.043 Msun for the Be star and the companion, respectively. Previous cross-correlation of the observed far-UV spectrum with sdO spectral model templates had not detected a companion belonging to the hot O-type subdwarf (sdO) population known from ~20 earlier-type Be stars. Guided by our full 3D orbital solution, we found a strong cross-correlation signal for a stripped subdwarf B-type companion (far-UV flux ratio of 2.3 +- 0.5%), enabling the first firm characterization of such a star, and making kappa Dra the first mid- to late-type Be star with a directly-observed subdwarf companion.Comment: Accepted to ApJ. Figure sets available on reques