A5062893293- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Mechanics and Biomechanics Studies
- High-pressure geophysics and materials
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Relativity and Gravitational Theory
- History and Developments in Astronomy
- Crystal Structures and Properties
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Geomagnetism and Paleomagnetism Studies
- Molecular Spectroscopy and Structure
- Geological and Geophysical Studies
- Veterinary Equine Medical Research
- Quasicrystal Structures and Properties
- Spectroscopy and Laser Applications
- Streptococcal Infections and Treatments
Centro de Astrobiología
2023-2024
University of Amsterdam
2020-2024
KU Leuven
2018-2024
Institute of Astronomy
2020-2024
Tel Aviv University
2024
Astronomical Institute of the Slovak Academy of Sciences
2022
University of Potsdam
2013-2020
Université de Montréal
2015
Eclipsing systems of massive stars allow one to explore the properties their components in great detail. We perform a multi-wavelength, non-LTE analysis three multiple system $\delta$ Ori A, focusing on fundamental stellar properties, winds, and X-ray characteristics system. The primary's distance-independent parameters turn out be characteristic for its spectral type (O9.5 II), but usage ${\rm \it Hipparcos}$ parallax yields surprisingly low values mass, radius, luminosity. Consistent...
Context. Spectroscopic analysis remains the most common method to derive masses of massive stars, fundamental stellar parameter. While binary orbits and pulsations can provide much sharper constraints on mass, these methods are only rarely applicable stars. Unfortunately, spectroscopic stars heavily depend detailed physics model atmospheres.
Massive binaries (MBs) play a crucial role in the Universe. Knowing distributions of their orbital parameters (OPs) is important for wide range topics, from stellar feedback to binary evolution channels, distribution supernova types gravitational wave progenitors, yet, no direct measurements exist outside Milky Way. The Tarantula Binary Monitoring was designed help fill this gap by obtaining multi-epoch radial velocity monitoring 102 MBs 30 Dor. In paper, we analyse 32 VLT/FLAMES...
The intriguing binary LS V +22 25 (LB-1) has drawn much attention following claims of it being a single-lined spectroscopic with 79-day orbit comprising B-type star and ~70 Msun black hole. Recent analyses have implied that the visible primary is stripped He-rich star. However, nature secondary, which was proposed to be hole, neutron star, or main sequence remains unknown. Based on 26 newly acquired observations, we perform an orbital analysis spectral disentangling LB-1 elucidate system....
We present new grids of Potsdam Wolf-Rayet (PoWR) model atmospheres for stars the nitrogen sequence (WN stars). The models have been calculated with latest version PoWR stellar atmosphere code spherical winds. WN include non-LTE solutions statistical equations complex atoms, as well radiative transfer equation in co-moving frame. Iron-line blanketing is treated help superlevel approach, while wind inhomogeneities are taken into account via optically thin clumps. Three our appropriate...
Wolf-Rayet stars of the carbon sequence (WC stars) are an important cornerstone in late evolution massive before their core collapse. As core-helium burning, hydrogen-free objects with huge mass-loss, they likely last observable stage collapse and thus promising progenitor candidates for type Ib/c supernovae. Their strong mass-loss furthermore provides challenges constraints to theory radiatively driven winds. Thus, determination WC star parameters is major importance several astrophysical...
The recent gravitational wave measurements have demonstrated the existence of stellar mass black hole binaries. It is essential for our understanding massive star evolution to identify contribution binary formation double holes. A promising way progress investigating progenitors systems and comparing predictions with local samples such as population in 30 Doradus Large Magellanic Cloud (LMC). Methods. To this purpose, we analyse a large grid detailed models at LMC metallicity initial primary...
Comprehensive spectral analyses of the Galactic Wolf-Rayet stars nitrogen sequence (i.e.\ WN subclass) have been performed in a previous paper. However, distances these objects were poorly known. Distances direct impact on "absolute" parameters, such as luminosities and mass-loss rates. The recent Gaia Data Release (DR2) trigonometric parallaxes includes nearly all our sample. In present paper, we apply new to previously analyzed rescale results accordingly. On this basis, revised catalog 55...
Stars which start their lives with spectral types O and early-B are the progenitors of core-collapse supernovae, long gamma-ray bursts, neutron stars, black holes. These massive stars primary sources stellar feedback in star-forming galaxies. At low metallicities, properties evolution not yet fully explored. Here we report a spectroscopic study 320 OB Small Magellanic Cloud. The data, obtained ESO Very Large Telescope, were analyzed using state-of-the-art atmosphere models. We find that...
HR 6819 was recently proposed to be a triple system consisting of an inner B-type giant + black hole binary with orbital period 40d and outer Be tertiary. This interpretation is mainly based on two inferences: that the emission attributed star stationary, star, which used as mass calibrator for hole, giant. We re-investigate properties by spectral disentangling atmosphere analysis disentangled spectra search possibly simpler alternative explanation 6819. Disentangling implies component not...
Context. Classical Wolf-Rayet (WR) stars are massive, hydrogen-depleted, post main-sequence that exhibit emission-line dominated spectra. For a given metallicity Z , exceeding certain initial mass M single WR (Z) can reach the phase through intrinsic mass-loss or eruptions (single-star channel). In principle, of lower masses via stripping binary interactions (binary Because winds become weaker at low it is commonly assumed channel dominates formation in environments with such as Small and...
Context: The star cluster R136 inside the LMC hosts a rich population of massive stars, including most stars known. strong stellar winds these very luminous impact their evolution and surrounding environment. We currently lack detailed knowledge wind structure that is needed to quantify this impact. Aims: To observationally constrain properties in R136, particular parameters related clumping. Methods: simultaneously analyse optical UV spectroscopy 53 O-type 3 WNh-stars using FASTWIND model...
Aims. To search for these rare objects, we study 32 Galactic O-type stars that were reported as SB1s in the literature. In our sample include Cyg X-1, which is known to host an accreting stellar-mass BH, and HD 74194, a supergiant fast X-ray transient, order validate methodology. The final goal characterise nature of unseen companions determine if they are MS stars, stripped helium triples, or compact objects such neutron BHs. Methods. After measuring radial velocities deriving orbital...
Observations of individual massive stars, super-luminous supernovae, gamma-ray bursts, and gravitational-wave events involving spectacular black-hole mergers, indicate that the low-metallicity Universe is fundamentally different from our own Galaxy. Many transient phenomena will remain enigmatic until we achieve a firm understanding physics evolution stars at low metallicity (Z). The Hubble Space Telescope has devoted 500 orbits to observe 250 Z in ultraviolet (UV) with COS STIS...
The recently reported observation of VFTS 243 is the first example a massive black-hole binary system with negligible interaction following formation. mass (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mo>≈</a:mo><a:mn>10</a:mn><a:msub><a:mi>M</a:mi><a:mo stretchy="false">⊙</a:mo></a:msub></a:math>) and near-circular orbit (<d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mi>e</d:mi><d:mo>≈</d:mo><d:mn>0.02</d:mn></d:math>) suggest that...
Given the uncertain evolutionary status of blue supergiant stars, their multiplicity properties hold vital clues to better understand origin and evolution. As part The Binarity at LOw Metallicity (BLOeM) campaign in Small Magellanic Cloud we present a multi-epoch spectroscopic survey 128 stars spectral type B5--F5, which roughly correspond initial masses range 6 30 solar masses. observed binary fraction for B5-9 supergiants is 25+/-6 % (10+/-4 %) 5+/-2 (0 A-F using radial velocity (RV)...
The blue supergiant (BSG) domain contains a large variety of stars whose past and future evolutionary paths are still highly uncertain. Since binary interaction plays crucial role in the fate massive stars, investigating multiplicity among BSGs helps shed light on such objects. We aim to estimate fraction sample Small Magellanic Cloud within Binarity at LOw Metallicity (BLOeM) survey. In total, we selected 262 targets with spectral types B0-B3 luminosity classes I-II. This work is based...
Wolf-Rayet (WR) stars have a severe impact on their environments owing to strong ionizing radiation fields and powerful stellar winds. Since these winds are considered be driven by pressure, it is theoretically expected that the degree of wind mass-loss depends initial metallicity WR stars. Following our comprehensive studies in Milky Way, M31, LMC, we derive parameters rates for all seven putatively single WN known SMC. Based data, discuss low-metallicity environment mass loss evolution The...
Massive WR stars are evolved massive characterized by strong mass-loss. Hypothetically, they can form either as single or mass donors in close binaries. About 40% of the known confirmed binaries, raising question to impact binarity on population. By performing a spectral analysis all multiple systems SMC, we obtain full set stellar parameters for each individual component. Mass-luminosity relations tested, and importance binary evolution channel is assessed. The performed with PoWR model...
Context . Massive Wolf–Rayet (WR) stars dominate the radiative and mechanical energy budget of galaxies probe a critical phase in evolution massive prior to core collapse. It is not known whether He-burning WR (classical WR; cWR) form predominantly through wind stripping (w-WR) or binary (b-WR). Whereas spectroscopy binaries has so-far largely been avoided because its complexity, our study focuses on 44 candidates Large Magellanic Cloud (LMC; metallicity Z ≈ 0.5 ⊙ ), which were identified...
The study of massive stars in different metallicity environments is a central topic current stellar research. spectral analysis requires adequate model atmospheres. computation such models difficult and time-consuming. Therefore, analyses are greatly facilitated if they can refer to existing grids models. Here we provide atmospheres for OB-type at metallicities corresponding the Small Large Magellanic Clouds, as well solar metallicity. In total, comprise 785 individual were calculated using...