A5043109896- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Geomagnetism and Paleomagnetism Studies
- Adaptive optics and wavefront sensing
- Atmospheric Ozone and Climate
- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Calibration and Measurement Techniques
- Solar Radiation and Photovoltaics
- Geophysics and Gravity Measurements
- Photoacoustic and Ultrasonic Imaging
- Ionosphere and magnetosphere dynamics
- Arctic and Antarctic ice dynamics
- Spectroscopy and Quantum Chemical Studies
- Advanced MRI Techniques and Applications
- Atomic and Subatomic Physics Research
- Spectroscopy and Laser Applications
- Magnetic and Electromagnetic Effects
- Reservoir Engineering and Simulation Methods
- Characterization and Applications of Magnetic Nanoparticles
- Atmospheric aerosols and clouds
Leibniz Institute for Astrophysics Potsdam
2015-2024
Leibniz Institute for Neurobiology
2014
The Second Workshop on Extreme Precision Radial Velocities defined circa 2015 the state of art Doppler precision and identified critical path challenges for reaching 10 cm s−1 measurement precision. presentations discussion key issues instrumentation data analysis workshop recommendations achieving this bold are summarized here. Beginning with High Accuracy Velocity Planet Searcher spectrograph, technological advances radial velocity (RV) measurements have focused building extremely stable...
PEPSI is the bench-mounted, two-arm, fibre-fed and stabilized Potsdam Echelle Polarimetric Spectroscopic Instrument for 2x8.4 m Large Binocular Telescope (LBT). Three spectral resolutions of either 43 000, 120 000 or 270 can cover entire optical/red wavelength range from 383 to 907 nm in three exposures. Two 10.3kx10.3k CCDs with 9-{\mu}m pixels peak quantum efficiencies 96 % record a total 92 echelle orders. We introduce new variant wave-guide image slicer 3, 5, 7 slices between %. A six...
The "B fields in OB stars" (BOB) collaboration is based on an ESO Large Programme, to study the occurrence rate, properties, and ultimately origin of magnetic massive stars. In framework this programme, we carried out low-resolution spectropolarimetric observations a large sample stars using FORS2 installed at VLT 8-m telescope. We determined field values with two completely independent reduction analysis pipelines. Our in-depth measurements shows that differences between our pipelines are...
We present the discovery of KELT-21b, a hot Jupiter transiting $V=10.5$ A8V star HD 332124. The planet has an orbital period $P=3.6127647\pm0.0000033$ days and radius $1.586_{-0.040}^{+0.039}$ $R_J$. set upper limit on planetary mass $M_P<3.91$ $M_J$ at $3\sigma$ confidence. confirmed nature companion using this Doppler tomographic observations to verify that transits These data also demonstrate orbit is well-aligned with stellar spin, sky-projected spin-orbit misalignment...
Aims. In a follow-up investigation we present Zeeman-Doppler maps of the weak-lined T Tauri star (WTTS) V410 Tau. As rapid rotating and typical WTTS stellar surface Tau is accessible to imaging techniques allows us detect reconstruct major magnetic features on this pre-main sequence star.
Within the context of "B fields in OB stars (BOB)" collaboration, we used HARPSpol spectropolarimeter to observe early B-type beta CMa (HD44743; B1 II/III) and epsilon (HD52089; B1.5 II). For both stars, consistently detected signature a weak (<30 G absolute value) longitudinal magnetic field. We determined physical parameters characterise their X-ray spectrum. CMa, our mode identification analysis led determining rotation period 13.6+/-1.2 days an inclination angle axis 57.6+/-1.7 degrees,...
We present a detailed temperature and magnetic investigation of the T Tauri star V410 Tau by means simultaneous Doppler- Zeeman-Doppler Imaging. Moreover we introduce new line profile reconstruction method based on singular value decomposition (SVD) to extract weak polarized profiles. One key features is that SVD profiles are amenable radiative transfer modeling within our Imaging code iMap. The also utilizes iterative regularization scheme which independent any additional surface...
ABSTRACT The study of exoplanets and especially their atmospheres can reveal key insights on evolution by identifying specific atmospheric species. For such investigations, high-resolution transmission spectroscopy has shown great success, for Jupiter-type planets. Towards the characterization smaller planets, super-Earth exoplanet 55 Cnc e is one most promising terrestrial studied to date. Here, we present a spectroscopic transit observation this planet, acquired with PEPSI instrument at...
Our main objective is to develop a denoising strategy increase the signal noise ratio of individual spectral lines stellar spectropolarimetric observations. We use multivariate statistics technique called Principal Component Analysis. The cross-product matrix observations diagonalized obtain eigenvectors in which original can be developed. This basis such that first contain greatest variance. Assuming uncorrelated possible by reconstructing data with truncated basis. propose method identify...
We observed the Saturn-mass and Jupiter-sized exoplanet HAT-P-19b to refine its transit parameters ephemeris as well shed first light on transmission spectrum. monitored host star over one year quantify flux variability correct spectrum for a slope caused by starspots. A of was spectroscopically with OSIRIS at Gran Telescopio Canarias in January 2012. The spectra target comparison covered wavelength range from 5600 7600 AA. One high-precision differential curve created integrating entire...
Context. Surface differential rotation and other global surface flows on magnetically active stars are among the observable manifestations of stellar dynamo working underneath. Therefore, such observations important for theory useful constraints solar studies as well. Aims. The K1-giant component long-period RS CVn-type binary system sigma Gem its flow pattern is revisited. Methods. We refine law from recovering spot migration pattern. apply a detailed cross-correlation technique to unique...
Solar spots appear to decay linearly proportional their size. The rate of solar is directly related magnetic diffusivity, which itself a key quantity for the length magnetic-activity cycle. Is linear spot also seen on other stars, and this in agreement with large range stellar activity cycle lengths? We investigate evolution starspots rapidly-rotating ($P_{\rm rot}$ $\approx$ 24 d) K0 giant XX Tri, using consecutive time-series Doppler images. Our aim obtain well-sampled movie surface over...
ABSTRACT In this work, we investigate the potassium excess absorption around 7699 Å of exoplanets HD189733b and HD209458b. For purpose, used high-spectral resolution transit observations acquired with 2 × 8.4 m Large Binocular Telescope (LBT) Potsdam Echelle Polarimetric Spectroscopic Instrument (PEPSI). a bandwidth 0.8 Å, present detection &gt;7σ an level 0.18 per cent for HD189733b. Applying same analysis to HD209458b, can set 3σ upper limit 0.09 cent, even though do not detect...
We present a magnetic-field surface map for both stellar components of the young visual binary ksi Boo AB (A: G8V, B: K5V). Employed are high resolution Stokes-V spectra obtained with Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at Large Binocular Telescope (LBT). Stokes V line profiles inverted our iMAP software compared to previous inversions. employed an iterative regularization scheme without need penalty function incorporated three-component description vector. The...
We investigate the application of artificial neural networks (ANNs) for interpretation Stokes profiles. have employed ANNs to approximate nonlinear inverse mapping between profiles and some underlying atmospheric parameters. This model is used in following carry out a fast non-iterative inversion synthetic photospheric infrared line Fe I λ15648 demonstrate that are capable yield accurate single valued estimates complete magnetic field vector, line-of-sight (LOS) velocity, microturbulence,...
We present the status of PEPSI, bench-mounted fibre-fed and stabilized "Potsdam Echelle Polarimetric Spectroscopic Instrument" for 2×8.4m Large Binocular Telescope in southern Arizona. PEPSI is under construction at AIP scheduled first light 2009/10. Its ultra-high-resolution mode will deliver an unprecedented spectral resolution approximately R=310,000 high efficiency throughout entire optical/red wavelength range 390-1050nm without need adaptive optics. Besides its polarimetric Stokes IQUV...
Magnetic fields are essential ingredients of many physical processes in the interiors and envelopes cool stars. Yet their direct detection characterisation is notoriously difficult, requiring high-quality observations advanced analysis techniques. Significant progress has been recently achieved by several types magnetic field studies on surfaces active In particular, complementary techniques topology mapping with polarisation data total flux measurements from intensity spectra have...
Models of magnetically driven accretion and outflows reproduce many observational properties T Tauri stars, but the picture is much less clear for Herbig Ae/Be due to poor knowledge their magnetic field strength topology. The Ae star PDS2 was previously included in two studies based on low-resolution spectropolarimetric observations. Only one these presence a weak mean longitudinal reported. In present study, first time, high-resolution HARPS observations are used investigate field. A firm...
The origin and evolution of magnetism in OB stars is far from being well understood. With approximately 70 magnetic known, any new object with unusual characteristics may turn out to be a key piece the puzzle. We report detection an exceptionally strong field He-strong B2IV star CPD-62 2124. Spectropolarimetric FORS2 HARPSpol observations were analysed by two independent teams procedures, concluding on longitudinal 5.2 kG. quantitative characterisation stellar atmosphere yields effective...
Context. Measuring surface differential rotation (DR) on different types of stars is important when characterizing the underlying stellar dynamo. It has been suggested that anti-solar DR laws can occur strong meridional flows exist.
Context. The major challenges for a fully polarized radiative transfer driven approach to Zeeman-Doppler imaging are still the enormous computational requirements. In every cycle of iterative interplay between forward process (spectral synthesis) and inverse (derivative based optimization) Stokes profile synthesis requires several thousand evaluations equation given stellar surface model.
Abstract Recently, we performed a complete study of the SB2 system HD 161701 with an orbital period 12.5 d, consisting HgMn primary and classical Ap secondary. Since this is first identified particular combination peculiar stars, presence magnetic field in both components considerable interest to astronomers studying stellar magnetism impact binary systems. Apart from 161701, only one other close systems component, 98088, currently known. Using high accuracy radial velocity planet searcher...