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Evolutionary models of massive stars are affected by uncertainties related to three-dimensional processes like convection. However, it is not computationally possible to simulate at the same time both the entire lifetime of a star and its fluid motions. 3D hydrodynamics simulations can be employed to study the fluid behaviour in very high detail for a short time-scale, which can be used to improve 1D models. The code PROMPI is a multi-dimensional hydrodynamics software developed specifically for simulations of the late phases in massive star interiors. In these proceedings, we present results from a new PROMPI simulation of the neon-burning shell in a 15 M© star, focusing on the interplay between convective turbulence and nuclear reactions. In particular, we show how it is possible to use the chemical composition to study the time evolution of the convective zone, which is subjected to turbulent entrainment.

A simple theoretical description is proposed aiming at a qualitative explanation of the observed in 11 dependences of the fluorescence from the resonant Rb levels excited by a single frequency diode laser on the magnetic field, when Hanle effect configuration of the experiment is used. The components of the statistical tensor for population and longitudinal alignment are calculated by iteration method up to fourth order terms. The spontaneous emission transfer influence is taken into account. A good qualitative agrement between calculated and experimentally observed resonances is obtained.

Laser induced Galvanic Signals (LIGS) were observed in a Se- buffer gas hollow cathode (HC) discharge irradiated by He- Se + or cw dye lasers. Radial and current dependences were studied. A similarity of the radial dependences for the two buffer gases He and Ne and maximum in the current dependences are registered. The possible mechanisms which form GS responses in Se HC discharge are discussed.

If a massive star has lost significant mass during its red supergiant stage it would return to blue region in the HR diagram and spend a part of the core He burning stage as a blue supergiant having a luminosity to mass ratio (L/M) considerably larger than about 10^4 (in solar units); the duration depends on the degree of internal mixing and on the metallicity. Then various stellar pulsations are excited by enhanced \kappa mechanism and strange mode instability. Assuming these pulsations to be responsible for (at least some of) the quasi periodic light and radial velocity variations in \alpha Cygni variables including luminous blue variables (LBVs; or S Dor variables) we can predict masses and surface compositions for these variables and compare them with observed ones to constrain the evolutionary models. We discuss radial pulsations excited in evolutionary models of an initial mass of 40 M_\odot with solar metallicity of Z=0.014 and compare them to micro variations in the two Galactic LBVs HR Car and HD 160529. We have found that these stars should has lost more than half of the initial mass and their surface CNO abundances should be significantly modified from the original ones showing partial H burning products.

Resonances with complex shape have been obtained experimentally in the magnetic field dependence of the optogalvanic signal induced in a Cu/Ne hollow cathode discharge by 632.8 nm laser radiation. Either population trapping or transfer of coherence are considered as possible mechanisms of formation of these resonances. Both of them, however, appear insufficient to obtain full qualitative explanation of the observed dependencies.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Magnetic confinement of the winds of hot, massive stars has far-reaching consequences on timescales ranging from hours to Myr. Understanding the long-term effects of this interplay has already led to the identification of two new evolutionary pathways to form `heavy' stellar mass black holes and pair-instability supernova even at galactic metallicity. We are performing 1D stellar evolution model calculations that, for the first time, account for the surface effects and the time evolution of fossil magnetic fields. These models will be thoroughly confronted with observations and will potentially lead to a significant revision of the derived parameters of observed magnetic massive stars., Comment: to appear in proceedings of 'Stars with a stable magnetic field: from pre-main sequence to compact remnants' conference, held in Brno, Czech Republic, 28 Aug - 1 Sep, 2017, Contributions of the Astronomical Observatory Skalnate Pleso, 2017

All ten LIGO/Virgo binary black hole (BH-BH) coalescences reported from the O1/O2 runs have near zero effective spins. There are only three potential explanations of this fact. If the BH spin magnitudes are large then (i) either both BH spin vectors must be nearly in the orbital plane or (ii) the spin angular momenta of the BHs must be oppositely directed and similar in magnitude. Or, (iii) the BH spin magnitudes are small. We test the third hypothesis within the framework of the classical isolated binary evolution scenario of the BH-BH merger formation. We test three models of angular momentum transport in massive stars: a mildly efficient transport by meridional currents (as employed in the Geneva code), an efficient transport by the Tayler-Spruit magnetic dynamo (as implemented in the MESA code), and a very-efficient transport (as proposed by Fuller et al.) to calculate natal BH spins. We allow for binary evolution to increase the BH spins through accretion and account for the potential spin-up of stars through tidal interactions. Additionally, we update the calculations of the stellar-origin BH masses, include revisions to the history of star formation and to the chemical evolution across cosmic time. We find that we can match simultaneously the observed BH-BH merger rate density, BH masses, and effective spins. Models with efficient angular momentum transport are favored. The updated stellar-mass weighted gas-phase metallicity evolution now used in our models appears to be a key in better reproducing the LIGO/Virgo merger rate estimate. Mass losses during the pair-instability pulsation supernova phase are likely overestimated if the merger GW170729 hosts a BH more massive than 50 Msun. We also estimate rate of BH-NS mergers from recent LIGO/Virgo observations. Our updated models of BH-BH, BH-NS and NS-NS mergers are now publicly available at www.syntheticuniverse.org., Comment: A&A accepted: revised comparison with LIGO/Virgo (41 pages)

We present a detailed study of stellar rotation in the massive 1.5 Gyr old cluster NGC 1846 in the Large Magellanic Cloud. Similar to other clusters at this age, NGC 1846 shows an extended main sequence turn-off (eMSTO), and previous photometric studies have suggested it could be bimodal. In this study, we use MUSE integral-field spectroscopy to measure the projected rotational velocities (vsini) of around 1400 stars across the eMSTO and along the upper main sequence of NGC 1846. We measure vsini values up to ~250 km/s and find a clear relation between the vsini of a star and its location across the eMSTO. Closer inspection of the distribution of rotation rates reveals evidence for a bimodal distribution, with the fast rotators centred around vsini = 140 km/s and the slow rotators centred around vsini = 60 km/s. We further observe a lack of fast rotating stars along the photometric binary sequence of NGC 1846, confirming results from the field that suggest that tidal interactions in binary systems can spin down stars. However, we do not detect a significant difference in the binary fractions of the fast and slowly rotating sub-populations. Finally, we report on the serendipitous discovery of a planetary nebula associated with NGC 1846., Comment: Accepted for publication in MNRAS, 15 pages, 10 figures

Mass discrepancy is one of the problems that is pending a solution in (massive) binary star research field. The problem is often solved by introducing an additional near core mixing into evolutionary models, which brings theoretical masses of individual stellar components into an agreement with the dynamical ones. In the present study, we perform a detailed analysis of two massive binary systems, V380 Cyg and Sigma Sco, to provide an independent, asteroseismic measurement of the overshoot parameter, and to test state-of-the-art stellar evolution models., 5 pages, 1 figure, 3 tables; proceedings of the IAU Symposium 307 held in Geneva in June 2014

After highlighting the principle and power of asteroseismology for stellar physics, we briefly emphasize some recent progress in this research for various types of stars. We give an overview of high-precision high duty-cycle space photometry of OB-type stars. Further, we update the overview of seismic estimates of stellar parameters of OB dwarfs, with specific emphasis on convective core overshoot. We discuss connections between pulsational, rotational, and magnetic variability of massive stars and end with future prospects for asteroseismology of evolved OB stars., Comment: Invited review paper to appear in Proc. IAU307: New windows on massive stars: asteroseismology, interferometry, and spectropolarimetry, Editors: G. Meynet, C. Georgy, J.H. Groh & Ph. Stee, 9 pages, 2 figures

We present Hubble Space Telescope photometry of NGC1850, a ~100 Myr, ~10^5 Msun cluster in the Large Magellanic Cloud. The colour magnitude diagram clearly shows the presence of an extended main sequence turnoff (eMSTO). The use of non-rotating stellar isochrones leads to an age spread of ~40 Myr. This is in good agreement with the age range expected when the effects of rotation in MSTO stars are wrongly interpreted in terms of age spread. We also do not find evidence for multiple, isolated episodes of star-formation bursts within the cluster, in contradiction to scenarios that invoke actual age spreads to explain the eMSTO phenomenon. NGC 1850 therefore continues the trend of eMSTO clusters where the inferred age spread is proportional to the age of the cluster. While our results confirm a key prediction of the scenario where stellar rotation causes the eMSTO feature, direct measurements of the rotational rate of MSTO stars is required to definitively confirm or refute whether stellar rotation is the origin of the eMSTO phenomenon or if it is due to an as yet undiscovered effect., MNRAS letters, in press