scholarly journals Observational study of the evolution of massive binary stars

1984 ◽  
Vol 105 ◽  
pp. 403-406
Author(s):  
G. Burki ◽  
M. Mayor
Keyword(s):  
Observational Study ◽  
Spectral Type ◽  
Binary Stars ◽  
Binary Systems ◽  
Radial Velocities ◽  
Total Rate ◽  
Luminosity Class ◽  
Observational Program

Six years ago an observational program on supergiant stars using CORAVEL was initiated at Geneva Observatory. About 1500 radial velocities were obtained out of a sample of 181 northern supergiants of F, G, K, M type. Nineteen new SB have been discovered and 16 others are suspected to be SB. The total rate of binary systems among northern supergiants is in the range of 31–38 % (Burki and Mayor, 1983). This value neither depends on spectral type nor luminosity class.

scholarly journals ASAS census of twins

2020 ◽  
Vol 496 (3) ◽  
pp. 2605-2612
Author(s):  
Volkan Bakış ◽  
Zeki Eker ◽  
Oğuzhan Sarı ◽  
Gökhan Yücel ◽  
Eda Sonbaş
Keyword(s):  
Spectral Type ◽  
Binary Stars ◽  
Binary Systems ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
Eclipsing Binary ◽  
Type Distribution ◽  
Eclipsing Binary Stars ◽  
Detached Binaries

ABSTRACT Twin binaries were identified among the eclipsing binaries with δ > –30° listed in the All Sky Automated Survey (ASAS) catalogue. In addition to the known twin binaries in the literature, 68 new systems have been identified and photometric and spectroscopic observations were done. Colour, spectral type, temperature, ratio of radii and masses of the components have been derived and are presented. Including 12 twin binary systems that exist in both ASAS and the catalogue of absolute parameters of detached eclipsing binary stars, a total of 80 twin detached binary systems have been statistically studied. A comparison of the spectral type distribution of the twins with those of detached eclipsing binary stars in the ASAS database shows that the spectral type distribution of twins is similar to that of detached systems. This result has been interpreted as indicating that there is no special formation mechanism for twins compared to normal detached binaries. As a result of our case study for HD 154010, a twin binary, we present the precise physical parameters of the system.

scholarly journals Uncovering the orbital dynamics of stars hidden inside their powerful winds: application to η Carinae and RMC 140

2020 ◽  
Vol 494 (1) ◽  
pp. 17-35 ◽  
Author(s):  
David Grant ◽  
Katherine Blundell ◽  
James Matthews
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Orbital Motion ◽  
Extreme Case ◽  
Flow Speed ◽  
Radial Velocities ◽  
Spectral Lines ◽  
Emission Region ◽  
Orbital Parameters ◽  
Balmer Lines

ABSTRACT Determining accurate orbits of binary stars with powerful winds is challenging. The dense outflows increase the effective photospheric radius, precluding direct observation of the Keplerian motion; instead, the observables are broad lines emitted over large radii in the stellar wind. Our analysis reveals strong, systematic discrepancies between the radial velocities extracted from different spectral lines: the more extended a line’s emission region, the greater the departure from the true orbital motion. To overcome these challenges, we formulate a novel semi-analytical model that encapsulates both the star’s orbital motion and the propagation of the wind. The model encodes the integrated velocity field of the out-flowing gas in terms of a convolution of past motion due to the finite flow speed of the wind. We test this model on two binary systems. (1) For the extreme case η Carinae, in which the effects are most prominent, we are able to fit the model to 10 Balmer lines from H α to H κ concurrently with a single set of orbital parameters: time of periastron T0 = 2454848 (JD), eccentricity e = 0.91, semi-amplitude $k=69 \, \rm {\, km \, s^{-1}}$, and longitude of periastron ω = 241°. (2) For a more typical case, the Wolf–Rayet star in RMC 140, we demonstrate that for commonly used lines, such as He ii and N iii/iv/v, we expect deviations between the Keplerian orbit and the predicted radial velocities. Our study indicates that corrective modelling, such as presented here, is necessary in order to identify a consistent set of orbital parameters, independent of the emission line used, especially for future high accuracy work.

scholarly journals Hunt for Binaries with Pulsating Components

2006 ◽  
Vol 2 (S240) ◽  
pp. 697-699
Author(s):  
Olivera Latković
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Astronomical Observatory ◽  
Curve Analysis ◽  
Radial Velocities ◽  
Eclipsing Binary ◽  
Spectroscopic Observations

AbstractIn the frame of the collaboration of several Southern European observatories, we are examining a number of eclipsing binary systems in search for evidence of pulsating phenomena. We hope our candidate systems will be suitable for subsequent astroseismological studies. As a first step towards this end, we are analyzing spectroscopic observations of several such binary stars; these observations have been made at the National Astronomical Observatory Rozhen, Bulgaria, in the period from 2002 to 2005, and the reduction was done at the Astronomical Observatory of Belgrade, Serbia. The measurements of radial velocities and RV curve analysis are in preparation.

Some Results of the Spectroscopic Study of Four Close Binary Systems of Early Spectral Types

1965 ◽  
Vol 5 ◽  
pp. 120-130
Author(s):  
T. S. Galkina
Keyword(s):  
Spectroscopic Study ◽  
Spectral Type ◽  
Spectroscopic Investigation ◽  
Binary Systems ◽  
Quantitative Information ◽  
Close Binary ◽  
Physical Parameters ◽  
Absorption And Emission ◽  
Close Binary Systems ◽  
Quantitative Estimates

It is necessary to have quantitative estimates of the intensity of lines (both absorption and emission) to obtain the physical parameters of the atmosphere of components.Some years ago at the Crimean observatory we began the spectroscopic investigation of close binary systems of the early spectral type with components WR, Of, O, B to try and obtain more quantitative information from the study of the spectra of the components.

scholarly journals Observed Relations Between Physical Properties and MK Classification as Functions of Metal Abundance for F5-K4 Stars

1976 ◽  
Vol 72 ◽  
pp. 75-78
Author(s):  
M. Grenon
Keyword(s):  
Physical Properties ◽  
Spectral Range ◽  
Spectral Type ◽  
Photometric System ◽  
Luminosity Class ◽  
Empirical Relations ◽  
Metal Abundance ◽  
Systematic Effects ◽  
The Absolute ◽  
Absolute Magnitudes

The Geneva photometric system has been calibrated in terms of [M/H], θeff, Mv in the spectral range F5 to K4. As the spectral type is a datum generally available, we derive empirical relations showing the coupling of θeff and [M/H] at given spectral type and luminosity class. Similar relations are offered for the absolute magnitudes and provide a more accurate means for deriving spectroscopic parallaxes. Systematic effects on the estimation of the luminosity class are also shown.

scholarly journals Interferometric Investigations of Eclipsing Binaries as a Key to an Improved Distance Scale

2006 ◽  
Vol 2 (S240) ◽  
pp. 496-498
Author(s):  
K. Shabun ◽  
A. Richichi ◽  
U. Munari ◽  
A. Siviero ◽  
B. Pacsysnki
Keyword(s):  
Spectral Type ◽  
Effective Temperature ◽  
Binary Systems ◽  
Angular Separation ◽  
Eclipsing Binaries ◽  
Multiple Systems ◽  
Long Baseline ◽  
Global Calibration ◽  
Empirical Calibration ◽  
Full Solution

AbstractBinary and multiple systems constitute one of the main tools for obtaining fundamental stellar parameters, such as masses, radii, effective temperatures and distances. One especially fortunate, and at the same time rare, occurrence is that of double-lined eclipsing binaries with well-detached components. In this special case, it is possible to obtain a full solution of all orbital and stellar parameters, with the exception of the effective temperature of one star, which is normally estimated from spectral type or derived from atmospheric analysis of the spectrum. Long-baseline interferometry at facilities such as the ESO VLTI is beginning to have the capability to measure directly the angular separation and the angular diameter of some selected eclipsing binary systems, and we have proposed such observations with the AMBER instrument. In particular, we aim at deriving directly the effective temperature of at least one of the components in the proposed system, thereby avoiding any assumptions in the global solution through the Wilson–Devinney method. We will also obtain an independent check of the results of this latter method for the distance to the system. This represents the first step towards a global calibration of eclipsing binaries as distance indicators. Our results will also contribute to the effective temperature scale for hot stars. The extension of this approach to a wider sample of eclipsing binaries could provide an independent method to assess the distance to the LMC. The observations will extend accurate empirical calibration to spectral type O9 – B0.

scholarly journals Hipparcos Positions of B/Be Stars on the HR Diagram

2000 ◽  
Vol 175 ◽  
pp. 117-128 ◽  
Author(s):  
Danielle Briot ◽  
Noel Robichon
Keyword(s):  
Spectral Type ◽  
Rotational Velocity ◽  
Absolute Magnitude ◽  
Be Stars ◽  
Class V ◽  
B Stars ◽  
Luminosity Class ◽  
The Mean ◽  
Absolute Magnitudes ◽  
Hipparcos Parallax

AbstractAbsolute magnitudes of Be and B stars are computed for each spectral type and luminosity class V and IV, using the Hipparcos parallax measurements. Some simulations have been carried out in order to estimate the effects which could bias the mean absolute magnitude calculations. As a result, only stars with σπ/π < 15% have been used. A first result is that B stars are fainter than previous estimations by about 0.5 magnitude on average. We then observe that on average Be stars are brighter than B stars of the same spectral type and this over-luminosity increases with the spectral type. A possible interpretation is proposed based on the fact that the rotational velocity of the late Be stars is near the critical rotational velocity.

scholarly journals The J vs. M Relation for Binary Stars

1989 ◽  
Vol 8 ◽  
pp. 137-138
Author(s):  
J. E. Tohline
Keyword(s):  
Angular Momentum ◽  
Binary Stars ◽  
Binary Systems ◽  
Environmental Temperature ◽  
Physical Systems ◽  
Young Binary Systems

AbstractFor a given mass M and environmental temperature T, there is a well-defined angular momentum Jmax above which physical systems cannot exist as self-gravitating entities. The quantity Jmax α M2 T−½. Observations of J and M in young binary systems should put useful constraints on the temperature of the medium from which they formed.

scholarly journals Spectroscopic Observations of the Early-Type Contact Binary AW Lacertae

1989 ◽  
Vol 107 ◽  
pp. 354-354
Author(s):  
Y. Nakamura ◽  
A. Okazaki ◽  
J. Katahira
Keyword(s):  
Spectral Type ◽  
Variable Stars ◽  
Radial Velocities ◽  
Early Type ◽  
Mass Ratio ◽  
Photometric Analysis ◽  
Spectroscopic Observations ◽  
Type Contact ◽  
Contact Binary ◽  
Photometric Solution

Abstract.Spectroscopic observations were performed of the early-type contact binary AW Lac with an image-intensified coude spectrograph of 1.9−m telescope at the Okayama Astro-physical Observatory. A total of twenty-two spectra covering blue region with a dispersion of 16 Amm−1 have been secured on Kodak IIa-O baked plates. In every spectra sharp interstellar Call H,K lines are clearly seen. The spectral type of AW Lac has been estimated as early B, which substantially confirms the one adopted in the photometric analysis by Jiang et al. (1983) and is diffrent from A0 listed in General Catalogue of Variable Stars (Kholopov et al. 1985). Contrary to the suggestion by the photometric solution of Jiang et al., no definite secondary lines could be separated, though some indications of light contamination due to the secondary component are surely observed. This would imply that the light ratio of the components should be somewhat smaller than that derived by photometric analysis. No emission features appeared either. The measurement of radial velocities of the primary component for the orbital elements was made for twenty spectra by a conventional method. It was difficult to measure the radial velocities because the lines are quite broadened and deformed. Hence the measured values for the radial velocities should be regarded as rather preliminary. The derived spectroscopic elements, combined with the photometric data, give the absolute dimensions of the system for each assumed mass ratio q. For q = 1, being the adopted photometric solution by Jiang et al., we obtain too small value for the primary’s mass, comparing with its spectral type. For the mass ratio as small as q = 0.6, we can obtain a reasonable value for the mass of the primary. However, in order to get more definite conclusion the cross-correlation method would be more appropriate for the spectroscopic analysis of this system.

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