Double-lined Binaries Research Articles

Study of physical properties of spectroscopic binary stars

The main results of a study of a catalogue of physical parameters of 1041 spectroscopic binaries are presented. The distribution of spectroscopic binaries over all main parametersM1, a, e, M1/M2, P, and certain dependencies between some of them have been found. (1) It appears that among bright (mv≲3m–5m) stars withM≳1M⊙, about 40% are apparently spectroscopic binaries with comparable masses of components. (2) The majority of spectroscopic binaries with the ratio of the large semiaxis of the orbit to the radius of the primarya/R1≲20, have eccentricities close to zero. This is probably a consequence of the tidal circularization of orbits of close binaries by viscous friction. (3) The discovery of duplicity of double-line spectroscopic binaries is possible only if the semiamplitude of radial velocityK1 is almost 10 times higher than the semiamplitude of the radial velocity of a single-line spectroscopic binary of the same mass. (4) Double-line spectroscopic binaries witha/R⊙≲6(M1/M⊙)1/3,M1≈M2≳1.5M⊙ are almost almost absent, and the number of stars witha/R⊙≲6(M1/M⊙)1/3,M1≈1.5M⊙ is relatively low. (5) The distribution of unevolved SB stars over the large semiaxis may be described by the expression d(Nd/Nt)≈0.2 d loga for 6(M1/M⊙)1/3≲a/R⊙≲100. (6) The intial mass-function for primaries of spectroscopic binaries is the same Salpeter function dNd≈M1−2.35dM1 for 1≲M1/M⊙≲30. (7) It is possible to explain the observed ratio of the number of single-line spectroscopic binaries to the number of double-line binaries if one assumes that the average initial mass ratio is close to 1 and that the mass of the postmass-exchange remnant of the primary exceeds the theoretical one and/or that half of the angular momentum of the system is lost during mass-exchange. (8) The above-mentioned distributions ofM1 anda and assumptions on the mass of remnant and/or momentum loss also allow us to explain the observed shapes of dN/dM, dN/dq, and dN/da distributions after some selection effects are taken into account.

Revised photometric elements of the eclipsing binaries XY Cet and V380 Cyg

Photoelectric light curves of the double-lined binaries XY Cet and V380 Cyg, known to be detached systems, have been reanalyzed by means of Wood's program in order to obtain homogeneous photometric elements. Masses, radii and luminosities are given.

Wolf-Rayet Binaries

An updated list of known spectroscopic double-line and single-line Galactic Wolf-Rayet binaries is presented. From this we discuss e.g. mass ratios, the binary frequency and the evidence for low-mass unseen (compact?) companions. Spectroscopic binary orbits of several WR stars in the Magellanic Clouds are noted for the first time.

SPECTRAL MORPHOLOGY IN THE OPEN CLUSTER NGC 2287.

ABSTRACT Spectral classifications in NGC 2287 have revealed the presence of an He-weak star, three Hg-Mn stars, one star with a weak K line, one cool Ap star and one star with a composite spectrum. Spectroscopic evidence determined eight double-line binaries as well as five suspected double-line binaries.

Spectroscopic studies of O-type binaries. IV - HD 165052 and HD 167771

HD 165052, O6.5 V, and HD 167771, O7.5 III((f)), are double-lined binaries with periods of six and four days, respectively, and velocity semiamplitudes near 100 km/s. In the reported spectroscopic orbital analysis, the effect of correcting the measured radial velocities for pair blending is investigated. The derived velocity amplitudes are increased by roughly 7%, and hence the minimum masses increase by 20%-25%. The raw data lead to minimum masses, m times (sin i)-cubed, between 2 and 3 solar masses. Since normal O stars are thought to have masses greater than 20 solar masses, the orbits must be highly inclined to the line of sight. Stellar radii are derived from the luminosities and effective temperatures. For HD 167771, the requirement that neither component overfill its Roche lobe implies that each has a mass in the neighborhood of 30 solar masses or larger.

Further Evidence for Collapsed Objects in Binary Star Systems

IT would be of great interest to discover a collapsed object (neutron star or black hole) as one component of a binary star system. Trimble and Thorne1 have compiled a list of fifty candidate systems from Batten's2 catalogue. These are non-eclipsing single-line spectroscopic binaries in which the unseen companion has a mass estimated to be greater than 1.4 M⊙. These unseen companions are thus too massive to be non-rotating white dwarfs (although the possibility that they are rapidly, differentially rotating white dwarfs cannot be completely excluded as Ostriker and Bodenheimer3 have shown). In principle, some of these unseen companions could be neutron stars or black holes. In most cases, including all those to be considered here, the unseen companion is less massive than the observed primary star and can be a normal main-sequence star, which is not observed simply because it is considerably less luminous than the primary. Recently, however, Gibbons and Hawking4 have presented evidence that suggests that one or more of the systems on the Trimble and Thorne list contain collapsed objects. Their argument is as follows. Let the initial binary system consist of two stars with masses M1 and M2. Let the more evolved star (M1) eject some of its mass and collapse to form a neutron star or black hole with gravitational mass MN1. The ejected mass-energy can be in the form of a shell of matter or gravitational radiation, for example. If the initial orbit is circular and the mass loss can be treated as instantaneous and spherically symmetric, then the resultant binary system (M2, MN1) will have an orbital eccentricity given by (Note: the notation for the star masses above is not the usual notation for spectroscopic binaries.) Three of the seven systems from the Trimble and Thorne list with P 0.08. By a comparison with short-period double-line binaries Gibbons and Hawking concluded that the probability of this occurring by chance is only 8%. This suggests that in one or more of the three systems, the eccentricity arises from a sudden mass loss and that the unseen companion is a collapsed object rather than a main-sequence star.

Orbits of Two Double-lined Binaries HD 140008 and 178322

Radial velocities of the spectroscopic binaries HD 140008 and 178322 are presented and orbits derived. Both stars show two very similar spectra and periods near 12 days. The double-lined character of HD 178322 was not previously known. Membership of the Sco–Cen association is strengthened for HD 140008 by the derived value of the γ velocity; HD 178322, regarded as a “probable member” by Blaauw, has a γ velocity deviating by +12.5 km/s from the predicted velocity.

Photoelectric Studies of Five Eclipsing Binaries.

view Abstract Citations (53) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric Studies of Five Eclipsing Binaries. Huffer, C. M. ; Kopal, Zdenek Abstract Light-curves of the five eclipsing binaries vV Orionis, Rz Cassiopeiae, U Ophiuchi, WW Aurigae, and TV Cassiopeiae have been completed at the Washburn Observatory. These photoelectric measures were made mostly during 1948 and 1949, with the 1P21 photomultiplier, which has an effective wave length of 4600 A. The computations were made at the Massachusetts Institute of Technology. Kopal's method was used, the numerical computations being performed with electric desk calculators. The stars U Ophiuchi and WW Aurigae are double-line binaries in which Petrie's line-intensity ratios aid in giving definite solutions from partial eclipses. The brighter star is the larger in each case. TV Cassiopeiae is less certain because of poor secondary lines but its fainter component appears also to be the smaller of the two. Rz Cassiopeiae loses over 80 per cent of its light at primary minimum, when the fainter, larger star is in front; but a search by Struve failed to detect the secondary spectrum. vV Orionis is a case of total and annular eclipses of a single-line binary. Because of the shallow eclipses and the uncertainty of the measures, it was not possible to determine the darkening coefficients from the investigations. Publication: The Astrophysical Journal Pub Date: September 1951 DOI: 10.1086/145468 Bibcode: 1951ApJ...114..297H full text sources ADS | data products SIMBAD (12)