J. H. M. M. Schmitt
A5050718741- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Astrophysics and Cosmic Phenomena
- History and Developments in Astronomy
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Atmospheric Ozone and Climate
- High-pressure geophysics and materials
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- Spectroscopy and Laser Applications
- Atomic and Molecular Physics
- Ionosphere and magnetosphere dynamics
- Particle Detector Development and Performance
- Space Exploration and Technology
- Nuclear Physics and Applications
- Geomagnetism and Paleomagnetism Studies
- Particle Accelerators and Free-Electron Lasers
Universität Hamburg
2016-2025
Hamburger Fern-Hochschule
2014-2024
Siemens (Germany)
2020-2022
Auburn University
2021
Max Planck Society
1991-2019
Max Planck Institute for Astronomy
2012-2019
Darmstadt University of Applied Sciences
2019
Instituto de Astrofísica de Andalucía
2014-2019
Institute of Space Sciences
2018
Château Gombert
2018
During its close approach to Earth, comet C/Hyakutake 1996 B2 was observed at extreme ultraviolet and x-ray wavelengths with the Röntgen X-ray Satellite Rossi Timing Explorer. The emission morphology symmetric respect a vector from comet's nucleus toward sun, but not around direction of motion interplanetary dust. A slowly varying large impulsive event that varied on time scales 1 2 hours were observed. An interaction between solar wind/solar magnetic field seems be most likely mechanism for...
We determine the radii and masses of 293 nearby, bright M dwarfs CARMENES survey. This is first time that such a large homogeneous high-resolution (R>80 000) spectroscopic survey has been used to derive these fundamental stellar parameters. derived using Stefan-Boltzmann's law. obtained required effective temperatures $T_{\rm eff}$ from spectral analysis we luminosities L integrated broadband photometry together with Gaia DR2 parallaxes. The mass was then determined mass-radius relation...
We present X-ray data for all entries of the Third Catalogue Nearby Stars (Gliese & Jahreiß 1991) that have been detected as sources in ROSAT all-sky survey. The catalogue contains 1252 yielding an average detection rate 32.9 percent. In addition to count rates, source parameters, hardness ratios, and fluxes we also list luminosities derived from Hipparcos parallaxes.
We present a final summary of all ROSAT X-ray observations nearby stars. All available with the PSPC, HRI and WFC have been matched CNS4 catalog stars results gathered in Nearby XUV-emitting Stars data base, via www from Home Page Hamburger Sternwarte at URL http://www.hs.uni-hamburg.de/DE/For/Gal/Xgroup/nexxus. New volume-limited samples F/G-stars ( pc), K-stars M-stars pc) are constructed within which detection rates more than 90% obtained; only one star (GJ 1002) remains undetected...
For the detailed statistical analysis of X-ray emission hot stars we selected all spectral type O and B listed in Yale Bright Star Catalogue searched for them ROSAT All-Sky Survey. In this paper describe selection preparation data present a compilation derived complete sample bright OB stars.
We present three transit observations of HD 189733 b obtained with the high-resolution spectrograph CARMENES at Calar Alto. A strong absorption signal is detected in near-infrared He I triplet 10830 Å all transits. During mid-transit, mean level $0.88\pm0.04$ % measured a $\pm$10 km s$^{-1}$ range net blueshift $-3.5\pm0.4$ (10829.84--10830.57 Å). The exhibits radial velocities $+6.5\pm3.1$ and $-12.6\pm1.0$ during ingress egress, respectively; planetary rest frame. show that stellar...
SOPHIE is a new fiber-fed echelle spectrograph in operation since October 2006 at the 1.93-m telescope of Observatoire de Haute-Provence. Benefiting from experience acquired on HARPS (3.6-m ESO), was designed to obtain accurate radial velocities (~3 m/s over several months) with much higher optical throughput than ELODIE (by factor 10). These enhanced capabilities have actually been achieved and proved invaluable asteroseismology exoplanetology. We present here concept, double-pass Schmidt...
Do extrasolar planets affect the activity of their host stars? Indications for chromospheric enhancement have been found a handful targets, but in X-ray regime, conclusive observational evidence is still missing. We want to establish sound basis confirm or reject major effects Star-Planet Interactions (SPI) stellar emissions. therefore conduct statistical analysis all known planet-bearing stars within 30pc distance dependencies on planetary parameters such as mass and semimajor axis. find...
Ultra hot Jupiters orbit very close to their host star and consequently receive strong irradiation that makes atmospheric chemistry different from the common gas giants. Here, we study atmosphere of one these particular planets, MASCARA-2b/KELT-20b, using four transit observations with high resolution spectroscopy facilities. Three were performed HARPS-N CARMENES. We simultaneously observed transits MuSCAT2 monitor possible spots in stellar surface. At resolution, transmission residuals show...
We present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5d of science operations, reveal high signal-to-noise solar-like oscillation spectra in all stars: About 20 modes may be clearly distinguished each star. discuss appearance spectra, use frequencies and frequency separations to provide radii, masses ages stars, comment light these prospects for inference other solar-type stars that will observe.
We present new X-ray observations obtained with Chandra ACIS-S of the HD 189733 system, consisting a K-type star orbited by transiting Hot Jupiter and an M-type stellar companion. report detection planetary transit in soft X-rays significantly larger depth than observed optical. The data favor 6-8%, versus broadband optical 2.41%. While we are able to exclude several possible origins for this deep transit, additional will be necessary fully possibility that coronal inhomogeneities influence...
Context: The main goal of the CARMENES survey is to find Earth-mass planets around nearby M-dwarf stars. Seven M-dwarfs included in sample had been observed before with HIRES and HARPS either were reported have one short period planetary companion (GJ15A, GJ176, GJ436, GJ536 GJ1148) or are multiple systems (GJ581 GJ876). Aims: We aim report new precise optical radial velocity measurements for these planet hosts test overall capabilities CARMENES. Methods: combined our Doppler those available...
Gas planets in close proximity to their host stars experience photoevaporative mass loss. The energy-limited escape concept is generally used derive estimates for the planetary mass-loss rates. Our photoionization hydrodynamics simulations of thermospheres hot gas show that valid only with a gravitational potential lower than $\log_\mathrm{10}\left( -\Phi_{\mathrm{G}}\right) < 13.11~$erg$\,$g$^{-1}$ because these radiative energy input efficiently drive wind. Massive and compact \gtrsim...
Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, and these losses affect physical chemical evolution. Studies atmospheric escape from have mostly relied on space-based observations the hydrogen Lyman-α line in far ultraviolet region, which is strongly affected by interstellar absorption. Using ground-based high-resolution spectroscopy, we detected excess absorption helium triplet at 1083 nanometers during transit Saturn-mass exoplanet WASP-69b, a...
Context: Recently, the He I triplet at 10830 \r{A} has been rediscovered as an excellent probe of extended and possibly evaporating atmospheres close-in transiting planets. This already resulted in detections this a handful planets, both from space ground. However, while strong signal is expected for hot Jupiter HD 209458 b, only upper limits have obtained so far. Aims: Our goal to measure helium excess absorption b assess atmosphere planet possible evaporation. Methods: We new...
We present precise photospheric parameters of 282 M dwarfs determined from fitting the most recent version PHOENIX models to high-resolution CARMENES spectra in visible (0.52 - 0.96 $\mu$m) and near-infrared wavelength range (0.96 1.71 $\mu$m). With its aim search for habitable planets around dwarfs, several different masses have been detected. The characterization target sample is important ability derive constrain physical properties any planetary systems that are As a continuation...
For years, the standard procedure to measure radial velocities (RVs) of spectral observations consisted in cross-correlating spectra with a binary mask, that is, simple stellar template contains information on position and strength absorption lines. The cross-correlation function (CCF) profiles also provide several indicators activity. We present methodology first build weighted masks and, second, compute CCF these from which we derive activity indicators. These methods are implemented...
The CARMENES instrument was conceived to deliver high-accuracy radial velocity (RV) measurements with long-term stability search for temperate rocky planets around a sample of nearby cool stars. broad wavelength coverage designed provide range stellar activity indicators assess the nature potential RV signals and valuable spectral information help characterise targets. Data Release 1 (DR1) makes public all observations obtained during guaranteed time observations, which ran from 2016 2020...
Context . The first eROSITA all-sky survey (eRASS1) performed on board the Spectrum-Roentgen-Gamma mission (SRG) provides more than 900 000 X-ray sources in 0.2–2.3 keV band located western hemisphere. Aims We present identifications of eRASS1 obtained using our HamStar method, which was designed for identification coronal sources. Methods is a Bayesian framework that estimates probabilities each source based cross-match with optical counterparts from Gaia DR3. It considers geometric...
We present the first X-ray spectrum obtained by Low-Energy Transmission Grating Spectrometer (LETGS) aboard Chandra X-Ray Observatory. The is of Capella and covers a wavelength range 5-175 Å (2.5-0.07 keV). measured resolution, which in good agreement with ground calibration, Deltalambda approximately 0.06 (FWHM). Although in-flight calibration LETGS progress, high spectral resolution unique coverage are well demonstrated results from Capella, coronal source rich emission lines. While...
We present a detailed study of rotation and differential analyzing high resolution spectra 142 F-, G- early K-type field stars. Using Least Squares Deconvolution we obtain broadening profiles for our sample stars use the Fourier transform method to determine projected rotational velocities . Distributions periods are studied in HR-diagram. For subsample 32 spectral type F0–G0 derive amount terms find evidence ten Differential seems be more common slower rotators, but deviations from rigid...