M. Steffen
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View article: Surface image and activity-corrected orbit of the RS CVn binary HR 7275: Disentangling activity tracers
Surface image and activity-corrected orbit of the RS CVn binary HR 7275: Disentangling activity tracers Open
Quantifying stellar parameters and magnetic activity for cool stars in double-lined spectroscopic binaries (SB2) is not straightforward, as both stars contribute to the observed composite spectra and are likely variable. Disentangled compo…
View article: Multiregional accounting of corporate carbon emissions
Multiregional accounting of corporate carbon emissions Open
Corporations routinely use environmentally-extended input-output models to estimate and report greenhouse gas emissions upstream in their supply chain. However, the most widely used of such models assume that the structure of supply chains…
View article: SDSS J102915.14+172927.9: Revisiting the chemical pattern
SDSS J102915.14+172927.9: Revisiting the chemical pattern Open
Context . The small- to intermediate-mass (M < 0.8 M ⊙ ), most metal-poor stars that formed in the infancy of the Universe are still shining today in the sky. They are very rare, but their discovery and investigation brings new knowledge o…
View article: MINCE
MINCE Open
Context . Most of the studies on the determination of the chemical composition of metal-poor stars have been focused on the search of the most pristine stars, searching for the imprints of the ejecta of the first supernovae. Apart from the…
View article: The PEPSI Exoplanet Transit Survey (PETS). V: New Na D transmission spectra indicate a quieter atmosphere on HD 189733b
The PEPSI Exoplanet Transit Survey (PETS). V: New Na D transmission spectra indicate a quieter atmosphere on HD 189733b Open
Absorption lines from exoplanet atmospheres observed in transmission allow us to study atmospheric characteristics such as winds. We present a new high-resolution transit time-series of HD 189733b, acquired with the PEPSI instrument at the…
View article: MINCE II. Neutron capture elements
MINCE II. Neutron capture elements Open
The MINCE (Measuring at Intermediate metallicity Neutron-Capture Elements) project aims to gather the abundances of neutron-capture elements but also of light elements and iron peak elements in a large sample of giant stars in this metalli…
View article: Hot bubbles of planetary nebulae with hydrogen-deficient winds
Hot bubbles of planetary nebulae with hydrogen-deficient winds Open
Aims . We seek to understand the evolution of Wolf–Rayet central stars by comparing the diffuse X-ray emission from their windblown bubbles with that from their hydrogen-rich counterparts with predictions from hydrodynamical models. Method…
View article: Issue Information: Astron. Nachr. 1/2024
Issue Information: Astron. Nachr. 1/2024 Open
View article: Issue Information: Astron. Nachr. 10/2023
Issue Information: Astron. Nachr. 10/2023 Open
View article: Effects of magnetic fields on the center-to-limb variation in solar-type stars
Effects of magnetic fields on the center-to-limb variation in solar-type stars Open
Context. High-precision photometry of exoplanet transits obtained with the Kepler satellite allows one to derive information on the center-to-limb variation (CLV) of the host stars. Recent analyses indicate a small but systematic discrepan…
View article: VPNEP: Detailed characterization of TESS targets around the Northern Ecliptic Pole
VPNEP: Detailed characterization of TESS targets around the Northern Ecliptic Pole Open
Context. We embarked on a high-resolution optical spectroscopic survey of bright Transiting Exoplanet Survey Satellite (TESS) stars around the Northern Ecliptic Pole (NEP), dubbed the Vatican-Potsdam-NEP (VPNEP) survey. Aims. Our NEP cover…
View article: On the lithium abundance of the visual binary components $ξ$ Boo A (G8V) and $ξ$ Boo B (K5V)
On the lithium abundance of the visual binary components $ξ$ Boo A (G8V) and $ξ$ Boo B (K5V) Open
A spectroscopic investigation of the lithium resonance doublet in $ξ$ Boo A and $ξ$ Boo B in terms of both abundance and isotopic ratio is presented. We obtained new $R$=130\,000 spectra with a signal-to-noise ratio (S/N) per pixel of up t…
View article: On the lithium abundance of the visual binary components <i>ξ</i> Boo A (<scp>G8V</scp>) and <i>ξ</i> Boo B (<scp>K5V</scp>)
On the lithium abundance of the visual binary components <i>ξ</i> Boo A (<span>G8V</span>) and <i>ξ</i> Boo B (<span>K5V</span>) Open
A spectroscopic investigation of the lithium resonance doublet in ξ Boo A and ξ Boo B in terms of both abundance and isotopic ratio is presented. We obtained new R = 130,000 spectra with a signal‐to‐noise ratio (S/N) per pixel of up to 320…
View article: Issue Information: Astron. Nachr. 08/2022
Issue Information: Astron. Nachr. 08/2022 Open
View article: The solar photospheric silicon abundance according to CO<sup>5</sup>BOLD
The solar photospheric silicon abundance according to CO<sup>5</sup>BOLD Open
Context. In this work, we present a photospheric solar silicon abundance derived using CO 5 BOLD model atmospheres and the LINFOR3D spectral synthesis code. Previous works have differed in their choice of a spectral line sample and model a…
View article: Issue Information: Astron. Nachr. 05/2022
Issue Information: Astron. Nachr. 05/2022 Open
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View article: Measuring Emissions from a Demonstrator Heavy-Duty Diesel Vehicle under Real-World Conditions—Moving Forward to Euro VII
Measuring Emissions from a Demonstrator Heavy-Duty Diesel Vehicle under Real-World Conditions—Moving Forward to Euro VII Open
The European Union (EU) has introduced since the early 1990s a series of progressively more stringent emission regulations to control air pollution from the transport sector, commonly known as Euro standards. Following this path, more rece…
View article: Barium lines in high-quality spectra of two metal-poor giants in the Galactic halo
Barium lines in high-quality spectra of two metal-poor giants in the Galactic halo Open
Context. Theoretical results showed the possibility that neutron capture elements were produced in the early Universe by two different sources: a frequent s -process source hosted by rotating massive stars, and a rare r -process source hos…
View article: The <i>Gaia</i> RVS benchmark stars
The <i>Gaia</i> RVS benchmark stars Open
Context. The Radial Velocity Spectrometer (RVS) on board the Gaia satellite is not provided with a wavelength calibration lamp. It uses its observations of stars with known radial velocity to derive the dispersion relation. To derive an ac…
View article: Barium lines in high-quality spectra of two metal-poor giants in the Galactic halo
Barium lines in high-quality spectra of two metal-poor giants in the Galactic halo Open
Context. Theoretical results showed the possibility that neutron capture elements were produced in the early Universe by two different sources: a frequent s-process source hosted by rotating massive stars, and a rare r-process source hoste…
View article: 3D spectroscopic analysis of helium-line white dwarfs
3D spectroscopic analysis of helium-line white dwarfs Open
In this paper, we present corrections to the spectroscopic parameters of DB and DBA white dwarfs with −10.0 ≤ log (H/He) ≤ −2.0, 7.5 ≤ log g ≤ 9.0, and $12\, 000$ ≲ Teff $\lesssim 34\, 000\,\mathrm{ K}$, based on 282 3D atmospheric models …
View article: The solar gravitational redshift from HARPS-LFC Moon spectra
The solar gravitational redshift from HARPS-LFC Moon spectra Open
Context. The general theory of relativity predicts the redshift of spectral lines in the solar photosphere as a consequence of the gravitational potential of the Sun. This effect can be measured from a solar disk-integrated flux spectrum o…
View article: The solar gravitational redshift from HARPS-LFC Moon spectra. A test of the General Theory of Relativity
The solar gravitational redshift from HARPS-LFC Moon spectra. A test of the General Theory of Relativity Open
The General Theory of Relativity predicts the redshift of spectral lines in the solar photosphere, as a consequence of the gravitational potential of the Sun. This effect can be measured from a solar disk-integrated flux spectrum of the Su…
View article: Probing the atmosphere of HD189733b with the Na i and K i lines
Probing the atmosphere of HD189733b with the Na i and K i lines Open
High spectral resolution transmission spectroscopy is a powerful tool to characterize exoplanet atmospheres. Especially for hot Jupiters, this technique is highly relevant, due to their high-altitude absorption, e.g. from resonant sodium (…
View article: 16th Potsdam Thinkshop: The rotation periods of cool stars: Measurements, uses, connections and prospects
16th Potsdam Thinkshop: The rotation periods of cool stars: Measurements, uses, connections and prospects Open
This topical issue of Astronomische Nachrichten/Astronomical Notes contains a cross section of the articles that were presented at the 16th Potsdam Thinkshop, which was organized by the Leibniz Institute for Astrophysics Potsdam (AIP) and …
View article: Improving spectroscopic lithium abundances. Fitting functions for 3D non-LTE corrections in FGK stars of different metallicity
Improving spectroscopic lithium abundances. Fitting functions for 3D non-LTE corrections in FGK stars of different metallicity Open
Accurate spectroscopic lithium abundances are essential in addressing a variety of open questions, such as the origin of a uniform lithium content in the atmospheres of metal-poor stars (Spite plateau) or the existence of a correlation bet…
View article: Improving spectroscopic lithium abundances
Improving spectroscopic lithium abundances Open
Context. Accurate spectroscopic lithium abundances are essential in addressing a variety of open questions, such as the origin of a uniform lithium content in the atmospheres of metal-poor stars (Spite plateau) or the existence of a correl…
View article: Synthese und Charakterisierung von biobasierten Polyalkylsuccinaten zur Anwendung in Schmelzklebstoffen
Synthese und Charakterisierung von biobasierten Polyalkylsuccinaten zur Anwendung in Schmelzklebstoffen Open
Es wurden biobasierte Polyester und Polyestermischungen entwickelt, mit dem Ziel, diese zur kommerziellen Verklebung von Papier- und Kartonverpackungen zu nutzen. Die Polyester basieren auf Bernsteinsäure, die zu Polybutylensuccinat (PBS),…
View article: Issue Information: Astron. Nachr. 1/2020
Issue Information: Astron. Nachr. 1/2020 Open
View article: Issue Information: Astron. Nachr. 4/2019
Issue Information: Astron. Nachr. 4/2019 Open