Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userNon-synchronous rotations in massive binary systems. HD93343 revisited
67
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Context. Most massive stars are in binary or multiple systems. Several massive stars have been detected as doublelined spectroscopic binaries and among these, the OWN Survey has detected a non-negligible number whose components show very different spectral line broadening (i.e., projected rotational velocities). This fact raises a discussion about the contributing processes, such as angular-momentum transfer and tidal forces. Aims. We seek to constrain the physical and evolutionary status of one of such systems, the O+O binary HD 93343. Methods. We analyzed a series of high-resolution multiepoch optical spectra to determine the orbital parameters, projected rotational velocities, and evolutionary status of the system. Results. HD 93343 is a binary system comprised of two O7.5 Vz stars that each have minimum masses of approximately 22 Mo in a wide and eccentric orbit (e = 0.398$pm$0.004; P=50.432$pm$0.001 d). Both stars have very similar stellar parameters, and hence ages. As expected from the qualitative appearance of the combined spectrum of the system, however, these stars have very different projected rotational velocities (~65 and ~325 km/s, respectively). Conclusions. The orbits and stellar parameters obtained for both components seem to indicate that their youth and relative separation is enough to discard the effects of mass transfer and tidal friction. Thus, non-synchronization should be intrinsic to their formation.
rate research
Read More
Aims: We simulate the spectra of massive binaries at different phases of the orbital cycle, accounting for the gravitational influence of the companion star on the shape and physical properties of the stellar surface. Methods: We used the Roche potential modified to account for radiation pressure to compute the stellar surface of close circular systems and we used the TIDES code for surface computation of eccentric systems. In both cases, we accounted for gravity darkening and mutual heating generated by irradiation to compute the surface temperature. We then interpolated NLTE plane-parallel atmosphere model spectra in a grid to obtain the local spectrum at each surface point. We finally summed all contributions, accounting for the Doppler shift, limb-darkening, and visibility to obtain the total synthetic spectrum. We computed different orbital phases and sets of physical and orbital parameters. Results: Our models predict line strength variations through the orbital cycle, but fail to completely reproduce the Struve-Sahade effect. Including radiation pressure allows us to reproduce a surface temperature distribution that is consistent with observations of semi-detached binary systems. Conclusions: Radiation pressure effects on the stellar surface are weak in (over)contact binaries and well-detached systems but can become very significant in semi-detached systems. The classical von Zeipel theorem is sufficient for the spectral computation. Broad-band light curves derived from the spectral computation are different from those computed with a model in which the stellar surfaces are equipotentials of the Roche potential scaled by the instantaneous orbital separation. In many cases, the fit of two Gaussian/Lorentzian profiles fails to properly measure the equivalent width of the lines and leads to apparent variations that could explain some of the effects reported in the literature.
Recently, W. Slofstra proved that the set of quantum correlations is not closed. We prove that the set of synchronous quantum correlations is not closed, which implies his result, by giving an example of a synchronous game that has a perfect quantum approximate strategy but no perfect quantum strategy. We also exhibit a graph for which the quantum independence number and the quantum approximate independence number are different. We prove new characterisations of synchronous quantum approximate correlations and synchronous quantum spatial correlations. We solve the synchronous approximation problem of Dykema and the second author, which yields a new equivalence of Connes embedding problem in terms of synchronous correlations.
We have carried out a spectroscopic variability survey of some of the most massive stars in the Arches cluster, using K-band observations obtained with SINFONI on the VLT. One target, F2, exhibits substantial changes in radial velocity; in combination with new KMOS and archival SINFONI spectra, its primary component is found to undergo radial velocity variation with a period of 10.483+/-0.002 d and an amplitude of ~350 km/s. A secondary radial velocity curve is also marginally detectable. We reanalyse archival NAOS-CONICA photometric survey data in combination with our radial velocity results to confirm this object as an eclipsing SB2 system, and the first binary identified in the Arches. We model it as consisting of an 82+/-12 M_sun WN8-9h primary and a 60+/-8 M_sun O5-6 Ia+ secondary, and as having a slightly eccentric orbit, implying an evolutionary stage prior to strong binary interaction. As one of four X-ray bright Arches sources previously proposed as colliding-wind massive binaries, it may be only the first of several binaries to be discovered in this cluster, presenting potential challenges to recent models for the Arches age and composition. It also appears to be one of the most massive binaries detected to date; the primarys calculated initial mass of >~120 M_sun would arguably make this the most massive binary known in the Galaxy.
Aluminium-26 is a short-lived radionuclide with a half-life of 0.72Myr, which is observed today in the Galaxy via gamma-ray spectroscopy and is inferred to have been present in the early Solar System via analysis of meteorites. Massive stars are considered the main contributors of Al26. Although most massive stars are found in binary systems, the effect, however, of binary interactions on the Al26 yields have not been investigated since Braun & Langer (1995). Here we aim to fill this gap. We have used the MESA stellar evolution code to compute massive (10Msun<=M<=80Msun), non-rotating, single and binary stars of solar metallicity (Z=0.014). We computed the wind yields for the single stars and for the binary systems where mass transfer plays a major role. Depending on the initial mass of the primary star and orbital period, the Al26 yield can either increase or decrease in a binary system. For binary systems with primary masses up to ~35-40Msun, the yield can increase significantly, especially at the lower mass-end, while above ~45Msun the yield becomes similar to the single star yield or even decreases. Our preliminary results show that compared to supernova explosions, the contribution of mass-loss in binary systems to the total Al26 abundance produced by a stellar population is minor. On the other hand, if massive star mass-loss is the origin of Al26 in the early Solar System, our results will have significant implications for the identification of the potential stellar, or stellar population, source.
We present a new set of radial-velocity measurements of the spectroscopic binary HD 165052 obtained by disentangling of high-resolution optical spectra. The longitude of the periastron (60 +- 2 degrees) shows a variation with respect to previous studies. We have determined the apsidal motion rate of the system (12.1 +- 0.3 degree/yr), which was used to calculate the absolute masses of the binary components: M_1 = 22.5 +- 1.0 and M_2 = 20.5 +- 0.9 solar masses. Analysing the separated spectra we have re-classified the components as O7Vz and O7.5Vz stars.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
