scholarly journals The s-process nucleosynthesis in massive stars: current status and uncertainties due to convective overshooting

Astrophysics ◽  
10.5772/34308 ◽  
2012 ◽  
Author(s):  
Maria Letizia
Keyword(s):  
Massive Stars ◽  
Current Status

scholarly journals The MiMeS project: overview and current status

2010 ◽  
Vol 6 (S272) ◽  
pp. 118-123 ◽  
Author(s):  
Gregg A. Wade ◽  
Evelyne Alecian ◽  
David A. Bohlender ◽  
Jean-Claude Bouret ◽  
David H. Cohen ◽  
...  
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Massive Stars ◽  
Data Modeling ◽  
Current Status ◽  
Individual Stars ◽  
Related Theory ◽  
The Status ◽  
Very High

AbstractThe Magnetism in Massive Stars (MiMeS) Project is a consensus collaboration among many of the foremost international researchers of the physics of hot, massive stars, with the basic aim of understanding the origin, evolution and impact of magnetic fields in these objects. At the time of writing, MiMeS Large Programs have acquired over 950 high-resolution polarised spectra of about 150 individual stars with spectral types from B5-O4, discovering new magnetic fields in a dozen hot, massive stars. The quality of this spectral and magnetic matériel is very high, and the Collaboration is keen to connect with colleagues capable of exploiting the data in new or unforeseen ways. In this paper we review the structure of the MiMeS observing programs and report the status of observations, data modeling and development of related theory.

scholarly journals Core Overshoot and Nonrigid Internal Rotation of Massive Stars: Current Status from Asteroseismology

2007 ◽  
Vol 3 (S250) ◽  
pp. 237-244 ◽  
Author(s):  
Conny Aerts
Keyword(s):  
Main Sequence ◽  
Massive Stars ◽  
Rotation Frequency ◽  
Current Status ◽  
Structure Parameters ◽  
B Stars ◽  
Surface Rotation ◽  
Oscillation Modes ◽  
Drastic Increase ◽  
Core Rotation

AbstractSeismic estimates of core overshoot have been derived from extensive high-precision photometric and spectroscopic ground-based (multisite) campaigns for five main-sequence B-type stars. For three of these, the ratio of the near-core rotation frequency to the surface rotation frequency could be estimated as well, from the identified oscillation modes. We summarise these seismic results obtained for B stars. Now that the technique of asteroseismology was proven to work for probing the interior of massive stars, we expect a drastic increase in the precision of the structure parameters from the space missions CoRoT and Kepler, as well as from currently ongoing ground-based campaigns, in the coming years.

scholarly journals Derivation of the Rotational Frequency of Massive Stars from Seismic Studies

2004 ◽  
Vol 215 ◽  
pp. 199-204 ◽  
Author(s):  
C. Aerts ◽  
R. Scuflaire ◽  
A. Thoul
Keyword(s):  
Main Sequence ◽  
High Spatial Resolution ◽  
Massive Stars ◽  
Accurate Determination ◽  
Rotation Frequency ◽  
Rotational Frequency ◽  
Current Status ◽  
B Stars ◽  
Made In

In this contribution we review the current status of the determination of the rotational frequency in non-radially pulsating B stars, i.e. β Cep stars and slowly pulsating B stars. Considerable progress is currently being made in the understanding of the non-radial oscillations of main-sequence B stars by means of high-temporal, high-spatial resolution spectroscopic time series. This has led to the detection of frequency multiplets, which are interpreted as rotationally splitted non-radial modes and which allow an accurate determination of the surface rotational frequency in some stars. We outline how our future goal, i.e. the derivation of the internal rotation frequency, can be achieved.

scholarly journals Masers as Kinematic Signposts in Star Formation Regions

2000 ◽  
Vol 197 ◽  
pp. 223-231
Author(s):  
Ray P. Norris
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
High Precision ◽  
Massive Stars ◽  
Circumstellar Disks ◽  
Current Status ◽  
High Brightness ◽  
Infrared Wavelengths ◽  
Star Formation Regions ◽  
New Evidence

Masers have been well studied as indicators of star formation regions for over three decades. Their small size, high brightness, and narrow velocity width mean that we can measure their position and velocity with enormous accuracy, and so they stand out as high-precision signposts amidst the swirling gas that they sample. Nevertheless, in most cases the complexity of their kinematics has defied attempts to use them to unravel the processes of star formation. However, the last two or three years have seen a resurgence of interest in these masers because of exciting new evidence that, in some cases, they are tracing with high precision the kinematics of material in circumstellar disks around massive stars. The very existence of circumstellar disks around these massive stars is puzzling, and yet the maser results have now been confirmed by other data at radio and infrared wavelengths. In this paper I will review the current status of high-resolution maser observations, discuss some of the puzzles that are now confronting us, and speculate on where our current tentative steps may lead us.

scholarly journals Basic observational constraints on the evolution of massive stars

1984 ◽  
Vol 105 ◽  
pp. 233-254 ◽  
Author(s):  
Peter S. Conti
Keyword(s):  
Local Group ◽  
Massive Stars ◽  
Current Status ◽  
Mass Composition ◽  
Observational Constraints ◽  
Sources Of Information ◽  
Extensive Discussion ◽  
Short Summary ◽  
The Galaxy ◽  
Kinematic Properties

The sources of information and uncertainties in the intrinsic stellar parameters of luminosity, effective temperature, mass, composition and mass loss rates are discussed. These are used to compare the observed positions of massive stars in the Hertzsprung-Russell Diagram (HRD) with evolutionary tracks. The current status of this effort is briefly reviewed. A short summary of the kinematic properties of massive stars is made. A preliminary but fairly extensive discussion of the distributions and numbers of O-type and Wolf-Rayet stars in the galaxy and other members of the local group is then given.

scholarly journals An observational asteroseismic study of the pulsating B-type stars in the open cluster NGC 884

2013 ◽  
Vol 9 (S301) ◽  
pp. 479-480
Author(s):  
S. Saesen ◽  
M. Briquet ◽  
C. Aerts ◽  
A. Miglio ◽  
F. Carrier
Keyword(s):  
Chemical Composition ◽  
Recent Progress ◽  
Massive Stars ◽  
Open Cluster ◽  
Seismic Interpretation ◽  
Evolution Model ◽  
Stellar Structure ◽  
Current Status ◽  
Physical Description ◽  
Young Open Cluster

AbstractRecent progress in the seismic interpretation of field β Cep stars has resulted in improvements of the physical description in the stellar structure and evolution model computations of massive stars. Further asteroseismic constraints can be obtained from studying ensembles of stars in a young open cluster, which all have similar age, distance and chemical composition. We present an observational asteroseismic study based on the discovery of numerous multi-periodic and mono-periodic B-type stars in the open cluster NGC 884 (χ Persei). Our study illustrates the current status of ensemble asteroseismology of this young open cluster.

scholarly journals The Evolution of Massive Stars: The Production of “Single” WR Stars

1982 ◽  
Vol 99 ◽  
pp. 323-341 ◽  
Author(s):  
C. Chiosi
Keyword(s):  
Mass Loss ◽  
Turbulent Diffusion ◽  
Massive Stars ◽  
Current Status ◽  
Physical Mechanisms ◽  
Formation And Evolution ◽  
Theoretical Results

In this paper we summarize the basic observational properties of WR stars, and the current status of the evolution of massive stars, giving particular emphasis to those physical mechanisms (mass loss, overshooting, turbulent diffusion…) that may lead O type stars to the WR stage. We consider only those scenarios for WR formation and evolution that have been developed during the last few years and that appear to be sufficiently substanciated by observational and theoretical arguments. Finally, the theoretical results are compared with the observations, pointing out several still unsettled aspects of the problem.

scholarly journals Interpreting galaxy properties with improved modelling

2019 ◽  
Vol 15 (S352) ◽  
pp. 84-97
Author(s):  
E. R. Stanway ◽  
J. J. Eldridge
Keyword(s):  
Stellar Population ◽  
Massive Stars ◽  
High Redshift ◽  
Stellar Populations ◽  
Big Bang ◽  
Current Status ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Star Models ◽  
High Redshift Universe

AbstractObservations of star-forming galaxies in the distant Universe have confirmed the importance of massive stars in shaping galaxy emission and evolution. Distant stellar populations are unresolved, and the limited data available must be interpreted in the context of stellar population models. Understanding these populations, and their evolution with age and heavy element content is key to interpreting processes such as supernovae, cosmic reionization and the chemical enrichment of the Universe. With the upcoming launch of JWST and observations of galaxies within a billion years of the Big Bang, the uncertainties in modelling massive stars - particularly their interactions with binary companions - are becoming increasingly important to our interpretation of the high redshift Universe. In turn, observations of distant stellar populations provide ever stronger tests against which to gauge the success of, and flaws in, current massive star models. Here we briefly review the current status binary stellar population synthesis.

scholarly journals Formation of massive stars

2010 ◽  
Vol 6 (S270) ◽  
pp. 33-40
Author(s):  
Maria T. Beltrán
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Stars ◽  
Point Of View ◽  
High Mass ◽  
Observational Research ◽  
Current Status ◽  
Dark Clouds ◽  
Star Formation Activity ◽  
Infrared Dark Clouds

AbstractThe formation of high-mass stars represents a challenge from both a theoretical and an observational point of view. Here, we present an overview of the current status of the observational research on this field, outlining the progress achieved in recent years on our knowledge of the initial phases of massive star formation. The fragmentation of cold, infrared-dark clouds, and the evidence for star formation activity on some of them will be discussed, together with the kinematics of the gas in hot molecular cores, which can give us insights on the mechanism leading to the birth of an OB star.

scholarly journals A Korea-Japan planet search program: Current status and discovery of a brown dwarf candidate

2007 ◽  
Vol 3 (S249) ◽  
pp. 53-56
Author(s):  
Masashi Omiya ◽  
Hideyuki Izumiura ◽  
Bun'ei Sato ◽  
Michitoshi Yoshida ◽  
Eiji Kambe ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Massive Stars ◽  
Semimajor Axis ◽  
Current Status ◽  
Current View ◽  
Brown Dwarf ◽  
Intermediate Mass ◽  
Primary Star ◽  
Intermediate Mass Stars ◽  
Substellar Companions

AbstractSince 2005, we have been carrying out a precise radial velocity survey of about 190 intermediate-mass (1.5-5 M⊙) G and K giants at Bohyunsan Optical Astronomy Observatory (BOAO) in Korea and Okayama Astrophysical Observatory (OAO) in Japan, which aims to reveal statistical properties of planetary systems around intermediate-mass stars. We have finished the first screening of 120 stars so far and have identified 5 candidates with large periodic radial velocity variations. One of the candidates turned out to be orbited by a brown dwarf mass companion with minimum mass of 37.6 MJup and semimajor axis of 1.71 AU. The primary star has a mass of 3.9 M⊙, which ranks among the most massive stars with substellar companions. Our discovery may support the current view obtained from results of planet searches around intermediate-mass stars that massive substellar companions tend to form around massive stars.

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