scholarly journals The Slow Merger of Massive Stars: Merger Types and Post-Merger Evolution

2002 ◽  
Vol 187 ◽  
pp. 245-251
Author(s):  
N. Ivanova ◽  
Ph. Podsiadlowski
Keyword(s):  
Main Sequence ◽  
Massive Stars ◽  
Close Binary System ◽  
Composition Profile ◽  
Close Binary ◽  
Interior Structure ◽  
Subsequent Evolution ◽  
Core Mass ◽  
Common Envelope ◽  
Different Response

AbstractWe study the slow merger of two massive stars inside a common envelope. The initial close binary system consists of a massive red supergiant and a main-sequence companion of a few solar masses. The merger product is a massive supergiant with an interior structure (core mass and composition profile) which is significantly different from that of a single supergiant that has evolved in isolation. Using a parameterized approach for the stream–core interaction, we modelled the merger phase and have identified three qualitatively different merger types: quiet, moderate and explosive mergers, where the differences are caused by the different response of the He burning shell. In the last two scenarios, the post-merger He abundance in the envelope is found to be substantially increased, but significant s-processing is mainly expected in the case of an explosive merger scenario. The subsequent evolution of the merger product up to the supernova stage is also discussed.

scholarly journals V479 And: CV, LMXB, or Symbiotic?

2011 ◽  
Vol 7 (S281) ◽  
pp. 113-116
Author(s):  
Diego González Buitrago ◽  
Gagik Tovmassian ◽  
Juan Echevarría ◽  
Sergey Zharikov ◽  
Takamitsu Miyaji ◽  
...  
Keyword(s):  
Orbital Period ◽  
Main Sequence ◽  
Compact Object ◽  
Close Binary System ◽  
Close Binary ◽  
Stellar Winds ◽  
Primary Star ◽  
Giant Star ◽  
X Ray ◽  
Low Mass

AbstractV479 And is a 14.26 hour, close binary system, comprised of a G8-K0 star departing from the main sequence and a compact primary star accreting matter from the donor. The object is an X-ray source, modulated with the orbital period. This, and the presence of an intense He II line, leads us to speculate that the compact object is a magnetic white dwarf. However, we do not find strong constraints on the upper mass limit of the compact object, and we may have a neutron star in a low mass X-ray binary instead of a cataclysmic variable. The orbital period is certainly too short for the donor star to be an evolved giant star, so classifying this object as a symbiotic binary may be a big stretch; however there is an evidence that the mass transfer occurs via stellar winds, rather than through the L1 point of Roche filling secondary, a phenomenon more common for symbiotic stars.

scholarly journals Empirical Determination of the Gravity-Darkening Exponent for the Secondary Components Filling the Roche Lobe in Semi-Detached Close Binary Systems

1988 ◽  
Vol 108 ◽  
pp. 217-218
Author(s):  
Masatoshi Kitamura ◽  
Yasuhisa Nakamura
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Close Binary System ◽  
Roche Lobe ◽  
Close Binary ◽  
Close Binaries ◽  
Main Sequence Stars ◽  
Local Gravity ◽  
Subsurface Layers

The ordinary semi-detached close binary system consists of a main-sequence primary and subgiant (or giant) secondary component where the latter fills the Roche lobe. From a quantitative analysis of the observed ellipticity effect, Kitamura and Nakamura (1986) have deduced empirical values of the exponent of gravity-darkening for distorted main-sequence stars in detached systems and found that the empirical values of the exponent for these stars with early-type spectra are close to the unity, indicating that the subsurface layers of early-main sequence stars in close binaries are actually in radiative equilibrium. The exponent of gravity-darkening can be defined by H ∝ gα with H as the bolonetric surface brightness and g as the local gravity on the stellar surface.

scholarly journals Luminous red novae: Stellar mergers or giant eruptions?

2019 ◽  
Vol 630 ◽  
pp. A75 ◽  
Author(s):  
A. Pastorello ◽  
E. Mason ◽  
S. Taubenberger ◽  
M. Fraser ◽  
G. Cortini ◽  
...  
Keyword(s):  
Close Binary System ◽  
Light Curves ◽  
Close Binary ◽  
Late Time ◽  
Absorption Bands ◽  
Common Envelope ◽  
Balmer Lines ◽  
Alternative Scenarios ◽  
Stellar Mergers ◽  
Second Peak

We present extensive datasets for a class of intermediate-luminosity optical transients known as luminous red novae. They show double-peaked light curves, with an initial rapid luminosity rise to a blue peak (at −13 to −15 mag), which is followed by a longer-duration red peak that sometimes is attenuated, resembling a plateau. The progenitors of three of them (NGC 4490−2011OT1, M 101−2015OT1, and SNhunt248), likely relatively massive blue to yellow stars, were also observed in a pre-eruptive stage when their luminosity was slowly increasing. Early spectra obtained during the first peak show a blue continuum with superposed prominent narrow Balmer lines, with P Cygni profiles. Lines of Fe II are also clearly observed, mostly in emission. During the second peak, the spectral continuum becomes much redder, Hα is barely detected, and a forest of narrow metal lines is observed in absorption. Very late-time spectra (∼6 months after blue peak) show an extremely red spectral continuum, peaking in the infrared (IR) domain. Hα is detected in pure emission at such late phases, along with broad absorption bands due to molecular overtones (such as TiO, VO). We discuss a few alternative scenarios for luminous red novae. Although major instabilities of single massive stars cannot be definitely ruled out, we favour a common envelope ejection in a close binary system, with possibly a final coalescence of the two stars. The similarity between luminous red novae and the outburst observed a few months before the explosion of the Type IIn SN 2011ht is also discussed.

scholarly journals The Kinematics of Pulsars

1987 ◽  
Vol 125 ◽  
pp. 23-33
Author(s):  
A.G. Lyne
Keyword(s):  
Binary System ◽  
Supernova Remnants ◽  
Massive Stars ◽  
Normal Population ◽  
Hii Regions ◽  
Close Binary System ◽  
Close Binary ◽  
The Galaxy ◽  
Motion Measurements ◽  
Halo Population

Pulsars have a galactic radial distribution similar to that of many galactic populations such as HII regions, massive stars and supernova remnants. However they are generally much further from the plane of the Galaxy than these objects. Proper motion measurements sho that this is because they are typically moving with high velocities. The measurements also indicate that most pulsars were formed a few million years ago close to the plane, within the normal Population I regions. Some pulsars will escape from the Galaxy, although the majority will end up in a halo population. The origin of the high velocities is not clear at present but may be due either to some asymme try in the formation event or to the disruption of a close binary system.

scholarly journals Massive Binaries

2007 ◽  
Vol 3 (S250) ◽  
pp. 119-132
Author(s):  
Anthony F. J. Moffat
Keyword(s):  
Massive Stars ◽  
Formation Processes ◽  
Subsequent Evolution ◽  
X Ray ◽  
Common Envelope ◽  
Blue Stragglers ◽  
The Past ◽  
Thermal Radio Emission ◽  
The Universe

AbstractAs with all binaries, those that contain massive stars reveal various degrees of interaction, depending mainly on orbital separation and age, although things happen much faster in massive binaries. Those massive binaries with initial periods exceeding ~10 years generally only interact via wind-wind collisions, with little or no effect on their subsequent evolution (unless located in dense clusters). Shorter-period systems show even stronger wind-wind collisions as a rule, but also interact more directly via Roche Lobe Overflow or Common Envelope, with dramatic effects on their evolution. If we didn't have binaries among massive stars, we would be missing a whole host of interesting phenomena in the Universe, such as sources of enhanced stellar X-ray or non-thermal radio emission, WR dust-spirals, inverse mass-ratios, very rapid spin, rejuvenation and massive blue-stragglers, enhanced cluster dynamics, many runaways and possibly even SMBHs and GRBs! On the other hand, non(or little)-interacting massive binaries are also useful to provide information on Star-Formation processes and determination of stellar parameters (such as the mass) that would otherwise be difficult or impossible to obtain from single stars. In this review, I highlight some of the developments that have occurred during the past few years since the last IAU Symposium on Massive Stars in 2002.

scholarly journals The Occurrence of Different Wolf-Rayet Phases in Massive Close Binaries

1982 ◽  
Vol 99 ◽  
pp. 403-403
Author(s):  
C. Doom ◽  
J.P. De Grève
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Close Binary System ◽  
Close Binary ◽  
Close Binaries ◽  
Mass Ratio ◽  
The Third ◽  
Third Stage ◽  
Definition Of ◽  
Massive Close Binary

In a recent paper (Doom and De Grève, 1981) the remaining main sequence lifetime of the mass gaining component in massive close binary systems was computed. Using results of that paper and the definition of the four important events in the evolution of a massive close binary system (RLOF(M1), RLOF(M2), SN(M1), SN(M2)), four evolutionary stages in the life of the system can be defined: OB+OB, WR+OB, c+OB (or WR+WR) and c+WR. The two possibilities for the third stage depend on the initial mass ratio of the system. The final stage c+c, is not considered here.

scholarly journals Common envelope evolution

2011 ◽  
Vol 7 (S283) ◽  
pp. 95-102 ◽  
Author(s):  
Robert G. Izzard ◽  
Philip D. Hall ◽  
Thomas M. Tauris ◽  
Christopher A. Tout
Keyword(s):  
Binary System ◽  
Binary Systems ◽  
Binary Star ◽  
Short Review ◽  
Close Binary System ◽  
Asymptotic Giant Branch ◽  
Close Binary ◽  
Asymptotic Giant Branch Star ◽  
Common Envelope ◽  
The Core

AbstractMany binary star systems are not wide enough to contain the progenitor stars from which they were made. One explanation for this is that when one star becomes a red giant a common envelope forms around both stars in the binary system. The core of the giant and its companion star continue to orbit one another inside the envelope. Frictional energy deposited into the common envelope may lead to its ejection and, if so, a close binary system is formed from the core of the former giant star and its relatively untouched companion. When the primary is an asymptotic giant branch star the core becomes a hot carbon-oxygen white dwarf which may ionise the ejected envelope and illuminate a planetary nebula. Many other types of binary systems form through common envelope evolution such as low-mass X-ray binaries and cataclysmic variables. In the case of a failed envelope ejection when the cores merge, rapidly-rotating solitary giants similar to FK Comae stars form. In this short review we focus on attempts to constrain parameters of common envelope evolution models and also describe the latest efforts to model this elusive phase of binary stellar evolution.

scholarly journals Fossil magnetic fields in intermediate-mass and massive stars

2019 ◽  
Vol 82 ◽  
pp. 345-355 ◽  
Author(s):  
E. Alecian ◽  
F. Villebrun ◽  
J. Grunhut ◽  
G. Hussain ◽  
C. Neiner ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Star Formation ◽  
Magnetic Fields ◽  
Main Sequence ◽  
Massive Stars ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
Subsequent Evolution

A small fraction of the population of intermediate-mass and massive stars host strong and stable magnetic fields organised on large scales. These fields are believed to be remnants of star formation. It is however not clear how such fossil fields have been shaped during their formation and subsequent evolution. We report recent and ongoing studies on the magnetic properties of pre-main sequence stars and main sequence binaries, allowing us to make progress in this field.

scholarly journals Rotation: a fundamental parameter of massive stars

1997 ◽  
Vol 189 ◽  
pp. 343-348 ◽  
Author(s):  
N. Langer ◽  
A. Heger ◽  
J. Fliegner
Keyword(s):  
Main Sequence ◽  
Massive Stars ◽  
Large Fraction ◽  
Reasonable Doubt ◽  
Close Binary ◽  
Fundamental Parameter ◽  
Mixing Processes ◽  
B Stars ◽  
Internal Mixing ◽  
Rule Out

Massive stars are rapid rotators. Equatorial rotation velocities span the range vrot = 100–400 km s−1, with B stars rotating closest to their break-up speed vcrit (Howarth et al. 1997). During the last decade, many observations have revealed unusual surface abundances that may require additional internal mixing (beyond that of simple convection and overshooting) for their explanation, most important helium and nitrogen enrichment in main sequence O and B stars (Gies & Lambert 1992), in the SN 1987A progenitor (Fransson et al. 1989), and boron depletions in main sequence B stars (Venn et al. 1996). In particular the latter observations clearly point towards internal mixing and rule out a close binary origin of the abundance peculiarities (Fliegner et al. 1996). Altogether, the occurrence of some form of additional mixing responsible for altering the surface abundances in a large fraction, if not all massive stars appears to be beyond reasonable doubt, and mixing processes due to rotation are the most natural explanation.

scholarly journals Close Binary (and Pulsating) Nuclei of Planetary Nebulae

1979 ◽  
Vol 53 ◽  
pp. 266-268
Author(s):  
Howard E. Bond
Keyword(s):  
Angular Momentum ◽  
White Dwarf ◽  
Main Sequence ◽  
Planetary Nebulae ◽  
Close Binary ◽  
Common Envelope ◽  
Secondary Star ◽  
Cataclysmic Binaries ◽  
Red Giant ◽  
Central Stars

Close-binary central stars of planetary nebulae are of interest to participants in this Colloquium because of recent suggestions that the cataclysmic binaries, containing a white dwarf and a lower-main-sequence star, may be descended from such objects (e.g. Paczynski 1976; Ritter 1976; Webbink 1978; Meyer and Meyer-Hofmeister 1978; Livio, Salzman, and Shaviv 1979). The proposed scenario is. that a binary system of initially large separation (P.= 1-10 yr) forms a “common-envelope” binary after the primary has evolved to the red-giant stage and developed a degenerate core. The secondary star spirals inward inside the red-giant envelope, eventually transferring enough angular momentum to the envelope to eject it. The result is a close binary containing the hot degenerate core of the red giant and a cool main-sequence companion, surrounded by the ejected envelope, which is ionized by the hotter star. Much later, when the cool companion begins to evolve, it will start to transfer matter to the hot star (by now a white dwarf), and cataclysmic activity ensues.

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