A5017927399- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Nuclear physics research studies
- Geophysics and Gravity Measurements
- Relativity and Gravitational Theory
- Molecular Spectroscopy and Structure
- Astronomical and nuclear sciences
- Mechanics and Biomechanics Studies
- Dark Matter and Cosmic Phenomena
- Ionosphere and magnetosphere dynamics
- Paleontology and Evolutionary Biology
- Crystal Structures and Properties
University of Bonn
2015-2024
Max Planck Institute for Radio Astronomy
2011-2024
Lander Institute
2022
Max Planck Society
1993-2015
Trinity House
2014
Utrecht University
2003-2012
Max Planck Institute for Extraterrestrial Physics
2008-2011
Institut de Planétologie et d'Astrophysique de Grenoble
2010
European Southern Observatory
2010
Osservatorio Astronomico di Padova
2010
Many physically motivated extensions to general relativity (GR) predict substantial deviations in the properties of spacetime surrounding massive neutron stars. We report measurement a 2.01 ± 0.04 solar mass (M⊙) pulsar 2.46-hour orbit with 0.172 0.003 M⊙ white dwarf. The high and compact make this system sensitive laboratory previously untested strong-field gravity regime. Thus far, observed orbital decay agrees GR, supporting its validity even for extreme conditions present system....
How massive stars die—what sort of explosion and remnant each produces—depends chiefly on the masses their helium cores hydrogen envelopes at death. For single stars, stellar winds are only means mass loss, these a function metallicity star. We discuss how metallicity, simplified prescription for its effect affects evolution final fate stars. map, as where black holes neutron likely to form different types supernovae produced. Integrating over an initial function, we derive relative...
The presence of a nearby companion alters the evolution massive stars in binary systems, leading to phenomena such as stellar mergers, x-ray binaries, and gamma-ray bursts. Unambiguous constraints on fraction affected by interaction were lacking. We simultaneously measured all relevant characteristics sample Galactic O quantified frequency nature interactions. More than 70% will exchange mass with companion, merger one-third cases. These numbers greatly exceed previous estimates imply that...
We substantially update the capabilities of open-source software instrument Modules for Experiments in Stellar Astrophysics (MESA). MESA can now simultaneously evolve an interacting pair differentially rotating stars undergoing transfer and loss mass angular momentum, greatly enhancing prior ability to model binary evolution. New fully coupled calculation nuclear networks with hundreds isotopes allow accurately simulate advanced burning stages needed construct supernova progenitor models....
The evolution of rotating stars with zero-age main-sequence (ZAMS) masses in the range 8-25 M☉ is followed through all stages stable evolution. initial angular momentum chosen such that star's equatorial rotational velocity on ZAMS ranges from zero to ~ 70% breakup. rotate rigidly as a consequence redistribution during pre-main-sequence Redistribution and chemical species are then Eddington-Sweet circulation, Solberg-Høiland instability, Goldreich-Schubert-Fricke secular dynamic shear...
Massive stars are essential to understand a variety of branches astronomy including galaxy and star cluster evolution, nucleosynthesis supernovae, pulsars black holes. It has become evident that massive evolution is very diverse, being sensitive metallicity, binarity, rotation, possibly magnetic fields. While the problem obtain good statistical observational database alleviated by current large spectroscopic surveys, it remains challenge model these diverse paths towards their violent end...
We present a dense grid of evolutionary tracks and isochrones rotating massive main-sequence stars. provide three grids with different initial compositions tailored to compare early OB stars in the Small Large Magellanic Clouds Galaxy. Each covers masses ranging from 5 60 Msun rotation rates between 0 about 600 km/s. To calibrate our models we used results VLT-FLAMES Survey Massive Stars. determine amount convective overshooting by using observed drop for surface gravities log g < 3.2 width...
Abstract Double neutron star (DNS) systems represent extreme physical objects and the endpoint of an exotic journey stellar evolution binary interactions. Large numbers DNS their mergers are anticipated to be discovered using Square Kilometre Array searching for radio pulsars, high-frequency gravitational wave detectors (LIGO/VIRGO), respectively. Here we discuss all key properties systems, as well selection effects, combine latest observational data with new theoretical progress on various...
Recent models of rotating massive stars including magnetic fields prove it difficult for the cores single to retain enough angular momentum produce a collapsar and gamma-ray burst. At low metallicity, even very may hydrogen envelope due weakness stellar winds, posing an additional obstacle model. Here, we consider evolution massive, where rapid rotation induces almost chemically homogeneous evolution. We find that in this case, requirements model are rather easily fulfilled if metallicity is...
We systematically examine how the presence in a binary affects final core structure of massive star and its consequences for subsequent supernova explosion. Interactions with companion may change rate rotation, size helium core, strength carbon burning, iron mass. Stars initial masses larger than ~11 M☉ that experience collapse will generally have smaller cores at point explosion if they lost their envelopes through interaction during or soon after hydrogen burning. below M☉, on other hand,...
We investigate the evolution of surface properties models for rotating massive stars, i.e., their luminosities, effective temperatures, rotational velocities, and abundances all isotopes, from zero-age main sequence to supernova stage. Our results are based on grid stellar by Heger, Langer, & Woosley, which covers solar metallicity stars in initial-mass range 8-25 M☉. Results parameterized initial mass, velocity major uncertainties treatment mixing inside stars. Rotationally induced...
Aims. We analyze the multiplicity properties of massive O-type star population. With 360 stars, this is largest homogeneous sample stars analyzed to date. Methods. use multi-epoch spectroscopy and variability analysis identify spectroscopic binaries. also a Monte-Carlo method correct for observational biases. Results. observe binary fraction 0.35\pm0.03, which corresponds objects displaying statistically significant radial velocity variations with an amplitude at least 20km/s. compute...
We present grids of massive star evolution models at four different metallicities (Z=0.004, 0.002, 0.001, 0.00001). The effects rotation on the stellar structure and transport angular momentum chemical elements through Spruit-Tayler dynamo rotationally induced instabilities are considered. After discussing uncertainties involved with adopted physics, we elaborate final fate stars as a function initial mass spin rate, each considered metallicity. In particular, investigate for which...
The explosion of ultra-stripped stars in close binaries can lead to ejecta masses <0.1 M⊙ and may explain some the recent discoveries weak fast optical transients. In Tauris et al., it was demonstrated that helium star companions neutron (NSs) experience mass transfer evolve into naked ∼1.5 metal cores, barely above Chandrasekhar limit. Here, we elaborate on this work present a systematic investigation progenitor evolution leading supernovae (SNe). particular, examine binary parameter space...
With recent advances in gravitational-wave astronomy, the direct detection of gravitational waves from merger two stellar-mass compact objects has become a realistic prospect. Evolutionary scenarios towards mergers various double generally invoke so-called common-envelope evolution, which is poorly understood and leads to large uncertainties predicted rates. Here we explore, as an alternative, scenario massive overcontact binary (MOB) involves very stars tight that remain fully mixed result...
Rotation is thought to be a major factor in the evolution of massive stars—especially at low metallicity—with consequences for their chemical yields, ionizing flux, and final fate. Deriving birth spin distribution high priority given its importance as constraint on theories star formation input models stellar populations local universe redshift. Recently, it has become clear that majority stars interact with binary companion before they die. We investigate how this affects rotation rates,...
The first gravitational wave detections of mergers between black holes and neutron stars represent a remarkable new regime high-energy transient astrophysics. signals observed with LIGO-Virgo detectors come from extreme physical objects which are the end products stellar evolution in close binary systems. To better understand their origin merger rates, we have performed population syntheses at different metallicities using grid-based synthesis code ComBinE. Starting newborn pairs stars,...
Abundance anomalies observed in globular cluster stars indicate pollution with material processed by hydrogen burning. Two main sources have been suggested: asymptotic giant branch (AGB) and massive rotating near the break-up limit (spin stars). We propose binaries as an alternative source. compute evolution of a 20 Msun star close binary find that it sheds about 10 Msun. The ejecta are enriched He, N, Na, Al depleted C O, similar to abundance patterns gobular stars. In contrast fast,...
The VLT-FLAMES Tarantula Survey (VFTS) is an ESO Large Programme that has obtained multi-epoch optical spectroscopy of over 800 massive stars in the 30 Doradus region Magellanic Cloud (LMC). Here we introduce our scientific motivations and give overview survey targets, including near-infrared photometry comprehensive details data reduction. One principal objectives was to detect binary systems via variations their radial velocities, thus shaping observing strategy. Spectral classifications...
Because the majority of massive stars are born as members close binary systems, populations main-sequence contain stellar mergers and products mass transfer. We simulate accounting for all major evolution effects based on most recent parameter statistics extensively evaluate effect model uncertainties. Assuming constant star formation, we find that $8^{+9}_{-4}\,\%$ a sample early type to be product merger resulting from system. In total $30^{+10}_{-15}\,\%$ interaction. show commonly...
Observing more massive stars The number of that form at each mass is known as the initial function (IMF). For most masses, IMF follows a power-law distribution, first determined by Edwin Salpeter in 1955. Schneider et al. used observations nearby star-forming region 30 Doradus (also Tarantula Nebula) and combined these with stellar modeling to determine its IMF. They found above solar masses than predicted distribution. Because also have biggest influence on their surroundings—for instance,...