W. Brandner
A5082869565- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Molecular Spectroscopy and Structure
- Calibration and Measurement Techniques
- Pulsars and Gravitational Waves Research
- Advanced optical system design
- Advanced Measurement and Metrology Techniques
- Optical Systems and Laser Technology
- Space Exploration and Technology
- Spectroscopy and Laser Applications
- History and Developments in Astronomy
- Geophysics and Gravity Measurements
- Optical measurement and interference techniques
- Astrophysics and Cosmic Phenomena
- Optical Coherence Tomography Applications
- Atmospheric Ozone and Climate
- Solar and Space Plasma Dynamics
- Optical Wireless Communication Technologies
Max Planck Institute for Astronomy
2015-2024
Max Planck Institute for Extraterrestrial Physics
2005-2024
Université Paris Cité
2024
Laboratoire d’études spatiales et d’instrumentation en astrophysique
2024
Centre National de la Recherche Scientifique
2024
Sorbonne Université
2024
Université Paris Sciences et Lettres
2024
Université Grenoble Alpes
2024
University of Michigan
2023
Max Planck Society
2011-2021
The highly elliptical, 16-year-period orbit of the star S2 around massive black hole candidate Sgr A ✻ is a sensitive probe gravitational field in Galactic centre. Near pericentre at 120 AU ≈ 1400 Schwarzschild radii, has an orbital speed ≈7650 km s −1 , such that first-order effects Special and General Relativity have now become detectable with current capabilities. Over past 26 years, we monitored radial velocity motion on sky S2, mainly SINFONI NACO adaptive optics instruments ESO Very...
GRAVITY is a new instrument to coherently combine the light of European Southern Observatory Very Large Telescope Interferometer form telescope with an equivalent 130 m diameter angular resolution and collecting area 200 m$^2$. The comprises fiber fed integrated optics beam combination, high spectroscopy, built-in analysis control, near-infrared wavefront sensing, phase-tracking, dual operation laser metrology [...]. This article gives overview reports on performance first astronomical...
The star S2 orbiting the compact radio source Sgr A* is a precision probe of gravitational field around closest massive black hole (candidate). Over last 2.7 decades we have monitored star’s radial velocity and motion on sky, mainly with SINFONI NACO adaptive optics (AO) instruments ESO VLT, since 2017, four-telescope interferometric beam combiner instrument GRAVITY. In this Letter report first detection General Relativity (GR) Schwarzschild Precession (SP) in S2’s orbit. Owing to its highly...
We report the detection of continuous positional and polarization changes compact source SgrA* in high states ('flares') its variable near- infrared emission with near-infrared GRAVITY-Very Large Telescope Interferometer (VLTI) beam-combining instrument. In three prominent bright flares, position centroids exhibit clockwise looped motion on sky, scales typically 150 micro-arcseconds over a few tens minutes, corresponding to about 30% speed light. At same time, flares rotation angle,...
We present high-resolution, H-band, imaging observations, collected with Subaru/HiCIAO, of the scattered light from transitional disk around SAO 206462 (HD 135344B). Although previous sub-mm imagery suggested existence dust-depleted cavity at r~46AU, our observations reveal presence components as close 0.2" (~28AU) star. Moreover, we have discovered two small-scale spiral structures lying within 0.5" (~70AU). models for using density wave theory, and derive a aspect ratio h~0.1, which is...
Young circumstellar disks are of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections candidates within these exist, most them currently suspected be disk features. In this context, transition around young star PDS 70 is particular interest, due its large gap identified in previous observations, indicative ongoing formation. We aim search for presence planets structures disk-planet interactions other evolutionary...
We present a 0.16% precise and 0.27% accurate determination of R0, the distance to Galactic Center. Our measurement uses star S2 on its 16-year orbit around massive black hole Sgr A* that we followed astrometrically spectroscopically for 27 years. Since 2017, added near-infrared interferometry with VLTI beam combiner GRAVITY, yielding direct separation vector between an accuracy as good 20 micro-arcsec in best cases. passed pericenter highly eccentric May 2018, passage dense sampling...
Several exoplanets have recently been imaged at wide separations of >10 AU from their parent stars. These span a limited range ages (<50 Myr) and atmospheric properties, with temperatures 800--1800 K very red colors (J - H > 0.5 mag), implying thick cloud covers. Furthermore, substantial model uncertainties exist these young due to the unknown initial conditions formation, which can lead an order magnitude uncertainty in modeled planet mass. Here, we report direct imaging discovery Jovian...
We present the first near-IR scattered light detection of transitional disk associated with Herbig Ae star MWC 758 using data obtained as part Strategic Exploration Exoplanets and Disks Subaru, 1.1 micron HST/NICMOS data. While sub-millimeter studies suggested there is a dust-depleted cavity r=0.35, we find close 0.1 (20-28 AU) from star, no visible at H, K', or Ks. two small-scaled spiral structures which asymmetrically shadow outer disk. model one spirals density wave theory, derive aspect...
We report high-resolution 1.6 $\micron$ polarized intensity ($PI$) images of the circumstellar disk around Herbig Ae star AB Aur at a radial distance 22 AU ($0."15$) up to 554 (3.$"$85), which have been obtained by high-contrast instrument HiCIAO with dual-beam polarimetry. revealed complicated and asymmetrical structures in inner part ($\lesssim$140 AU) disk, while confirming previously reported outer ($r$ $\gtrsim$200 spiral structure. imaged double ring structure $\sim$40 $\sim$100...
We present the results of an extensive high-resolution imaging survey M-dwarf multiplicity using Lucky Imaging technique. The made use AstraLux Norte camera at Calar Alto 2.2m telescope and Sur ESO New Technology Telescope in order to cover nearly full sky. In total, 761 stars were observed (701 M-type 60 late K-type), among which 182 new 37 previously known companions detected 205 systems. Most targets have been during two or more epochs, could be confirmed as physical through common proper...
The stars orbiting the compact radio source Sgr A* in Galactic Centre are precision probes of gravitational field around closest massive black hole. In addition to adaptive optics assisted astrometry (with NACO / VLT) and spectroscopy SINFONI VLT, NIRC2 Keck GNIRS Gemini) over three decades, since 2016/2017 we have obtained 30-100 mu-as with four-telescope interferometric beam combiner GRAVITY VLTI reaching a sensitivity mK = 20 when combining data from one night. We present simultaneous...
The GRAVITY instrument on the ESO VLTI pioneers field of high-precision near-infrared interferometry by providing astrometry at $10 - 100\,\mu$as level. Measurements such high precision crucially depend control systematic effects. Here, we investigate how aberrations introduced small optical imperfections along path from telescope to detector affect astrometry. We develop an analytical model that describes impact measurement complex visibilities. Our formalism accounts for pupil-plane and...
We present new astrometric and polarimetric observations of flares from Sgr A* obtained with GRAVITY, the near-infrared interferometer at ESO's Very Large Telescope Interferometer (VLTI), bringing total sample well-covered to four ones six, where we have for two good coverage in both domains. All show clockwise motion plane sky a period around an hour, polarization vector rotates by one full loop same time. Given apparent similarities flares, common fit, taking into account absence strong...
Tight relationships exist in the local universe between central stellar properties of galaxies and mass their supermassive black hole. These suggest holes co-evolve, with main regulation mechanism being energetic feedback from accretion onto hole during its quasar phase. A crucial question is how relationship evolves time; a key epoch to probe this at peaks star formation growth 8-12 billion years ago (redshifts 1-3). Here we report dynamical measurement luminous redshift 2, look back time...
By using the GRAVITY instrument with near-infrared (NIR) Very Large Telescope Interferometer (VLTI), structure of broad (emission-)line region (BLR) in active galactic nuclei (AGNs) can be spatially resolved, allowing central black hole (BH) mass to determined. This work reports new NIR VLTI/GRAVITY interferometric spectra for four type 1 AGNs (Mrk 509, PDS 456, Mrk 1239, and IC 4329A) resolved broad-line emission. Dynamical modelling data constrains BLR radius BH measurements our targets...
We present HST/WFPC2 observations of a sample 134 ultra-cool objects (spectral types later than M7) coming from the DENIS, 2MASS and SDSS surveys, with distances estimated to range 7 pc 105 pc. Fifteen new binary candidates are reported here. Eleven known binaries confirmed orbital motion is detected in some them. estimate that closest systems this have periods between 5 20 years, thus dynamical masses will be derived near future. For calculation frequency we restrict ourselves less After...
The Adaptive Optics NIR Instrument NAOS-CONICA has been commissioned at the VLT (UT4) between November 2001 and March 2002. After summarizing observational capabilities of this multimode instrument in combination with powerful AO-system, we will present first on sky results instrumental performance for several non-direct imaging modes: High spatial resolution slit-spectroscopy optical thermal region tested. For compact sources below 2 arcsec extension, Wollaston prism polarimetry is used....
We present HST/NICMOS observations with 0.1" (15 AU) resolution of six young stellar objects in the Taurus star-formation region. The targets our survey are three Class I IRAS sources (IRAS 04016+2610, 04248+2612, and 04302+2247) low-luminosity stars (DG Tau B, Haro 6-5B, CoKu Tau/1) associated Herbig jets. broad-band images show that near-infrared radiation from these is dominated by light scattered dusty circumstellar material distributed a region 10 - 15 times size solar system. Although...
We present a systematic and homogeneous analysis of population gradients for the Local Group dwarf spheroidal galaxies (dSph's) Carina, Sculptor, Sextans, Tucana, Andromeda I–III, V, VI. For all Milky Way companions studied here, we find significant gradients. The same is true remote dSph Tucana located at outskirts Group. Among M31 companions, only I VI show obvious In cases where horizontal-branch (HB) morphology gradient visible, red HB stars are more centrally concentrated. occurrence...
We present the direct imaging discovery of an extrasolar planet, or possible low-mass brown dwarf, at a projected separation 55 +/- 2 AU (1.058 0.007 arcsec) from B9-type star Kappa And. The planet was detected with Subaru/HiCIAO during SEEDS survey, and confirmed as bound companion via common proper motion measurements. Observed near-infrared magnitudes J = 16.3 0.3, H 15.2 0.2, Ks 14.6 0.4, L' 13.12 0.09 indicate temperature ~1700 K. galactic kinematics host are consistent membership in...
We present the results of a survey 45 young (≲250 Myr), close (≲50 pc) stars with Simultaneous Differential Imager (SDI) implemented at VLT and MMT for direct detection extrasolar planets. As part survey, we observed 54 objects, consisting close, stars; two more distant (<150 pc), extremely (≤10 Myr) three known radial velocity planets; four older, very nearby (≤20 solar analogs. Our SDI devices use double Wollaston prism quad filter to take images simultaneously wavelengths surrounding 1.62...