scholarly journals The O-type spectroscopic binary system HD 93206

1979 ◽  
Vol 83 ◽  
pp. 277-280 ◽  
Author(s):  
Nancy D. Morrison ◽  
Peter S. Conti
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Mass Loss ◽  
Massive Stars ◽  
Radial Velocities ◽  
Mass Determination ◽  
Spectroscopic Binary ◽  
The Masses

The star HD 93206 (=QZ Carinae) is a double-lined (Conti et al. 1977), eclipsing (Moffat and Seggewiss 1972) binary with a period of 6 d. Walborn (1973) classified it 09.7Ib:(n). Since the star is probably a member of the cluster Collander 228 (which is near η Carinae), its distance can be assumed to be 2600 pc. In principle, one can determine the masses of the components of HD 93206 from observations of the radial velocities and the light curve, and a spectroscopic orbit is the object of this investigation. A mass determination for an evolved star such as this one is especially important for checking recently computed evolutionary tracks with mass loss for massive stars (de Loore et al. 1977, Chiosi et al. 1978, Dearborn et al. 1978).

scholarly journals Progenitors and Hydrodynamics of Type II and lb Supernovae

1996 ◽  
Vol 145 ◽  
pp. 137-147
Author(s):  
S. E. Woosley ◽  
T. A. Weaver ◽  
R. G. Eastman
Keyword(s):  
Black Holes ◽  
Light Curve ◽  
Mass Loss ◽  
Massive Stars ◽  
The Other ◽  
Shock Interaction ◽  
Type Ii ◽  
Residual Hydrogen ◽  
Ordinary Type ◽  
The One

We review critical physics affecting the observational characteristics of those supernovae that occur in massive stars. Particular emphasis is given to 1) how mass loss, either to a binary companion or by a radiatively driven wind, affects the type and light curve of the supernova, and 2) the interaction of the outgoing supernova shock with regions of increasing pr3 in the stellar mantle. One conclusion is that Type II-L supernovae may occur in mass exchanging binaries very similar to the one that produced SN 1993J, but with slightly larger initial separations and residual hydrogen envelopes (∼1 Mʘ and radius ∼ several AU). The shock interaction, on the other hand, has important implications for the formation of black holes in explosions that are, near peak light, observationally indistinguishable from ordinary Type II-p and lb supernovae.

scholarly journals The influence of mass loss on the evolution of binaries

1981 ◽  
Vol 59 ◽  
pp. 405-430 ◽  
Author(s):  
C. de Loore
Keyword(s):  
Neutron Star ◽  
Mass Loss ◽  
Massive Stars ◽  
Compact Object ◽  
Supernova Explosion ◽  
Sequence Evolution ◽  
Chemical Abundances ◽  
Low Mass Stars ◽  
Object A ◽  
The Masses

Mass loss can affect the evolution of binaries in various ways, during different stages of the evolution.1. For massive stars stellar wind mass loss will change the masses of the components during their main sequence evolution.2. During the Roche lobe overflow phase (or tidal interaction phase) matter can leave the system.3. For low mass stars matter can leave the system during the mass exchange phase and can be stored in envelopes, disks or rings.4. Sufficiently massive stars(>8-15M0) undergo at the end of their life a supernova explosion, where most of the matter is blown away and a compact object, a neutron star or a black hole can be left.5. For intermediate stars one of the components can evolve into a degenerate He or CO dwarf; a reverse mass transfer can dump matter on this degenerate dwarf. If the conditions are favorable the white dwarf can explode with loss of matter, and a neutron star can be the result.6. The chemical abundances in the outer layers change.

scholarly journals Progenitor for Type Ic Supernova 2007bi

2011 ◽  
Vol 7 (S279) ◽  
pp. 427-428
Author(s):  
Takashi Yoshida ◽  
Hideyuki Umeda
Keyword(s):  
Light Curve ◽  
Mass Loss ◽  
Loss Rate ◽  
Main Sequence ◽  
Massive Stars ◽  
Mass Loss Rate ◽  
Mass Range ◽  
Stellar Mass ◽  
Core Collapse ◽  
Core Collapse Supernova

AbstractWe investigate the evolution of very massive stars with Z = 0.2 Z⊙ to constrain the progenitor of the extremely luminous Type Ic SN 2007bi. In order to reproduce the 56Ni amount produced in SN 2007bi, the range of the stellar mass at the zero-age main-sequence is expected to be 515 - 575M⊙ for pair-instability supernova and 110 - 280M⊙ for core-collapse supernova. Uncertainty in the mass loss rate affects the mass range appropriate for the explosion of SN 2007bi. A core-collapse supernova of a WO star evolved from a 110 M⊙ star produces sufficient radioactive 56Ni to reproduce the light curve of SN 2007bi.

scholarly journals Cepheid Variables: Period and Mass Determination

1995 ◽  
Vol 10 ◽  
pp. 594-596
Author(s):  
Pawel Moskalik
Keyword(s):  
Light Curve ◽  
Vibrational Modes ◽  
Mass Determination ◽  
The Galaxy ◽  
Cepheid Variables ◽  
Mass Calibration ◽  
The Masses ◽  
Standing Problem ◽  
Good Agreement

Determination of masses has been a long standing problem in the Cepheid research. Since the early days of Cepheid modeling different methods of mass calibration have lead to conflicting results, implying serious discrepancies between the evolution and pulsation theories (see Cox 1980 for a review). In recent years this situtation has been mostly remedied, and the Baade-Wesselink masses, pulsation masses and evolutionary masses are now in good agreement with each other (e.g., Gieren 1989). However, both the bump masses inferred from the position of the secondary bump on the light curve and the beat masses obtained from the period ratios of the double mode Cepheids turned out to be very resilient to a reconciliation.There are 13 Cepheids in the Galaxy in which two vibrational modes are simultaneously excited (e.g., Szabados 1988). The period ratios measured in these variables can be used in conjunction with the linear pulsation theory to infer the masses of these stars. The method was first applied by Petersen (1973) who obtained masses ranging from 1Mʘ to 3Mʘ for Cepheids with fundamental mode periods between 2.1 d and 6.3 d. Such ‘beat” masses are 2—4 times smaller than the evolutionary or Baade-Wesselink masses for these objects.

scholarly journals Searching for Earth-mass planets around α Centauri: precise radial velocities from contaminated spectra

2014 ◽  
Vol 14 (2) ◽  
pp. 173-176 ◽  
Author(s):  
Christoph Bergmann ◽  
Michael Endl ◽  
John B. Hearnshaw ◽  
Robert A. Wittenmyer ◽  
Duncan J. Wright
Keyword(s):  
Binary System ◽  
Radial Velocity ◽  
Binary Systems ◽  
Angular Separation ◽  
Radial Velocities ◽  
The Other ◽  
Cross Contamination ◽  
Star System ◽  
Spectroscopic Binary ◽  
Ongoing Project

AbstractThis work is part of an ongoing project which aims to detect terrestrial planets in our neighbouring star system α Centauri using the Doppler method. Owing to the small angular separation between the two components of the α Cen AB binary system, the observations will to some extent be contaminated with light coming from the other star. We are accurately determining the amount of contamination for every observation by measuring the relative strengths of the H-α and NaD lines. Furthermore, we have developed a modified version of a well-established Doppler code that is modelling the observations using two stellar templates simultaneously. With this method we can significantly reduce the scatter of the radial velocity (RV) measurements due to spectral cross-contamination and hence increase our chances of detecting the tiny signature caused by potential Earth-mass planets. After correcting for the contamination we achieve RV precision of ~2.5 m s−1 for a given night of observations. We have also applied this new Doppler code to four southern double-lined spectroscopic binary systems (HR159, HR913, HR7578 and HD181958) and have successfully recovered radial velocities for both components simultaneously.

scholarly journals Observations of Wolf-Rayet Binaries

1980 ◽  
Vol 88 ◽  
pp. 177-180
Author(s):  
Virpi S. Niemela
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Evolutionary Status ◽  
Preliminary Results ◽  
New Information ◽  
The Masses

In many recent papers dealing with computations of evolutionary sequences for massive stars with mass loss, the evolutionary status of Wolf- Rayet stars has been discussed. When one whishes to compare these theoretical computations with observations, it is of great importance to know the masses of Wolf-Rayet stars, which unfortunately are well determined only in a few cases. Estimates of the masses are provided by binaries with WR type components. I will report here preliminary results of spectrographic observations for 4 WN+OB systems, with new information about the masses of their components.

scholarly journals The Most Massive Heartbeat: Finding the Pulse of ι Orionis

2016 ◽  
Vol 12 (S329) ◽  
pp. 181-185
Author(s):  
Herbert Pablo ◽  
Noel Richardson ◽  
Jim Fuller ◽  
Anthony F. J. Moffat ◽  
Keyword(s):  
Binary System ◽  
Massive Stars ◽  
Type Star ◽  
Fundamental Properties ◽  
The Masses ◽  
First Time

Abstractι Orionis is a massive binary system consisting of O9III + B1 III/IV stars. Though the system has been well studied, much about its fundamental properties have been difficult to determine. In this paper we report on the discovery of the heartbeat phenomenon in ι Orionis making it the most massive heartbeat system currently known. Using this phenomenon we have found empirical values for the masses and radii of both components. Moreover, we report the detection of tidally induced oscillations in an O-type star for the first time. These discoveries open a new avenue for exploring asteroseismology in massive stars.

scholarly journals Two-Spot Modeling of Synoptic Light Curves of II PEG

1983 ◽  
Vol 71 ◽  
pp. 185-188
Author(s):  
G. La Fauci ◽  
M. Rodonò
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Computer Code ◽  
Light Curves ◽  
Stellar Surface ◽  
Single Line ◽  
Relative Location ◽  
Single Spot ◽  
Spectroscopic Binary ◽  
Circular Spot

The light curve (LC) of the single-line spectroscopic binary system II Peg (K2-3, IV-III) generally shows an asymmetrical and highly variable shape (Fig.l, left). Therefore, single circular spot models can be successfully applied only to symmetric LCs, as the 1977 one by Vogt (1981). When asymmetrical or almost flat LCs develop, as appears to be the rule for II Peg, at leasts two-spot modeling is required (Bopp and Noah 1980, Dorren and Guinan 1982).From classical single-spot models (Torres and Ferraz Mello 1973, Friedman and Gurtler 1975, Bopp and Evans 1973) we have developed a computer code including two separate circular spots of different size which are allowed to assume any relative location on the stellar surface. The model is symmetric with respect to the equator. The spots are assumed to radiate as back bodies with temperature ranging from 100 to 2000 degree lower than the temperature of the unspotted photosphere (4500°K).

scholarly journals The spectroscopic binary γ 2 Velorum

1979 ◽  
Vol 83 ◽  
pp. 287-289
Author(s):  
Virpi S. Niemelä ◽  
Jorge Sahade
Keyword(s):  
Binary System ◽  
Radial Velocities ◽  
Orbital Elements ◽  
Spectroscopic Binary

γ2 Velorum is the brightest binary system with a Wolf-Rayet component; it has been classified as a 09I+WC8 pair (Conti and Smith 1972). The orbital elements of this system were determined earlier by Ganesh and Bappu (1967) from spectrograms of 125 Å/mm dispersion, on the basis of the radial velocities from CIII-IV λ4652 Å emission for the WC component, andon the radial velocities from H absorption only, for the O star.

scholarly journals How massive the Wolf-Rayet stars are?

1981 ◽  
Vol 59 ◽  
pp. 307-310
Author(s):  
Virpi S. Niemelä
Keyword(s):  
Mass Loss ◽  
Binary Systems ◽  
Massive Stars ◽  
The Masses

If the Wolf-Rayet stars are produced by the evolution of massive stars with mass loss (Paczynski 1967, Conti 1976) from 0 stars to WN stars and thereafter to WC stars, then we may expect to observe a correlation of decreasing mean masses in the same sense as the evolution.Information about the masses of TO stars are obtained from studies of binary systems with WR components. Table 1 presents the today available data for the WN type stars.

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