Binary Orbital Motion Research Articles

Toward an Orbit for the High‐Luminosity Cepheid T Monocerotis

We have obtained new velocities of the long-period Cepheid T Mon from the ground and velocities of its hot companion with the Hubble Space Telescope (HST) and the International Ultraviolet Explorer (IUE). Although observations do not cover a full orbit, both the maximum and minimum orbital velocities have now been obtained. We present a preliminary orbit and discuss the uncertainties in the orbital parameters. The velocities for the companion appear to be inconsistent with binary orbital motion, and it is likely that the companion is itself a binary in a short-period orbit. The HST spectrum of the companion shows that it is a chemically peculiar star, probably magnetic. Because it is coupled with the more massive Cepheid, it must be very close to the zero-age main sequence. The well-determined mass function from the preliminary orbit implies that the inclination of the long-period system is close to 90°.

Interferometric measurements of binaries

This paper is a brief overview of the past performance and future promise of interferometry as applied to the study of binary stars. For the sake of brevity, the important results from infrared techniques in recent years are regretfully omitted here. It is probably unnecessary to remind the reader that the analysis of binary star orbital motions is the only direct means for the determination of stellar masses. Historically, stellar masses have resulted primarily from orbits that are sufficiently wide in angular separation to permit the astrometric determination of the motions of the individual components about the center of mass as well as the parallax of the system or from short-period spectroscopic/eclipsing binaries. The advent of long baseline optical interferometers holds the promise of a wealth of new stellar mass data through the direct resolution of spectroscopic binaries.

Evidence for Binary Orbital Motion of a Quasar Broad-Line Region

Analysis of spectra of the quasar 3C 390.3 covering a period of over 20 yr shows that the blueshifted peak of Hβ has been changing its radial velocity at an almost constant rate during this time. The radial velocity has increased by over 1500 km s-1. The lower limit to the period of radial velocity changes is 210 yr. Although very long periods cannot be excluded by the radial velocity curve alone, other considerations suggest that the period is ~300 yr. If the radial velocity changes are due to orbital motion, the radius of the orbit is ~0.3 pc and the total mass of the system is ~7 × 109 M☉. In the binary black hole model, the masses of the two holes are ~2.2 × 109 M☉ and ~4.4 × 109 M☉. A possible third peak claimed to be present in some 1974-1975 spectra is shown to be an instrumental artifact. The narrowness of the displaced peaks in 3C 390.3 objects requires that the broad-line region cloud motions are not governed solely by gravity. The black hole masses derived by Koratkar & Gaskell need to be increased significantly. This probably lowers accretion efficiencies to less than 1% of the Eddington limit.

VLBI astrometric identification of the radio emitting region in Algol and determination of the orientation of the close binary

A minute displacement of the radio source in Algol was measured by VLBI during two consecutive orbital revolutions of the close binary. The magnitude of the displacement unambiguously indicates that the less massive star of the close binary, a K subgiant, is the star responsible for the nonthermal radio emission of the system. This is consistent with the idea that the radio emission in Algol is related to the strong magnetic activity of the subgiant. The orientation and sense of the displacement on the sky that are directly deduced from our astrometric VLBI observations imply: (1) that the orbital plane of the close binary is at P.A. = +52 deg +/- 5 deg; and (2) that the sense of circulation of the close binary is clockwise, as seen on the sky. Thus, the long-period and close binary orbital motions are almost orthogonal and counterrevolving and this is relevant for evolution and dynamical studies.

The theoretical polarisation from the obliquely rotating envelopes of single stars

The polarimetric variability of stars possessing an obliquely rotating envelope is investigated in the optically thin, single electron scattering approximation. It is shown that in the point light source treatment, one is unable to distinguish between polarimetric variability occurring due to rotation about a body axis and (binary) orbital motion. Nor is it possible, from the polarimetric variability, to infer the physical geometry of the obliquely rotating envelope.

Interacting binary galaxies. III - Observations of NGC 1587/1588 and NGC 7236/7237

view Abstract Citations (39) References (57) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Interacting Binary Galaxies. III. Observations of NGC 1587/1588 and NGC 7236/7237 Borne, Kirk D. ; Hoessel, John G. Abstract The catalog of isolated galaxy pairs prepared by Karachentsev has been culled for its E-E constituents. Major disturbances have been identified in ~10% of all such pairs of ellipticals. CCD pictures and long-slit spectroscopic observations have been obtained at KPNO for the most photometrically distorted of these systems. Such pairs very likely represent strongly interacting, physically associated, binary elliptical galaxies. Radial variations of rotation velocity and velocity dispersion are extracted from the spectroscopic data for each of the two galaxies in a given pair. We describe here such observations for two Karachentsev pairs, Nos. 99 and 564. The observed disturbances in rotation velocity and luminosity distribution are discussed in terms of the gravitational interaction hypothesis. In light of this discussion, we believe that we have uncovered and identified observational evidence of tidal friction in action. The evidence includes U-shaped rotation velocity curves and the morphology of the observed luminosity asymmetries. Imaging and dynamical data such as presented here are essential to the numerical simulation of interacting binaries. A preceding companion paper (Paper II) describes a particular physical model and simulation technique, while the following companion paper (Paper IV) presents specific interaction models that successfully match all of the available data for K99 and K564. In NGC 1587, the brighter component of K99, we find one of the highest rotation rates known for an E2 galaxy of average luminosity. Its rotation rate (in units of the central velocity dispersion) is v_rot_/σ = 0.6. Because this rotation is in the same sense as the binary orbital motion, the net angular momentum in this isolated binary system is large, challenging simple tidal torque theories to identify the source of this momentum. It is possible that NGC 1587 is itself a merger remnant, with its spin being a relic of the orbital angular momentum in that previous binary interaction. Publication: The Astrophysical Journal Pub Date: July 1988 DOI: 10.1086/166454 Bibcode: 1988ApJ...330...51B Keywords: Astronomical Catalogs; Astronomical Photometry; Charge Coupled Devices; Elliptical Galaxies; Galactic Clusters; Galactic Evolution; Interacting Galaxies; Angular Momentum; Angular Velocity; Morphology; Velocity Distribution; Astrophysics; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 1587; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 1588; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 7236; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 7237; GALAXIES: INTERNAL MOTIONS; GALAXIES: STRUCTURE full text sources ADS | data products SIMBAD (16) NED (13) Related Materials (6) Part 1: 1984ApJ...287..503B Part 2: 1988ApJ...330...38B Part 4: 1988ApJ...330...61B Part 5: 1988ApJ...333..567B Part 6: 1989ApJ...336..655B Part 7: 1994ApJ...435...79B

Discovery of 9.3 S X-ray pulsations from 2S 1553-542 and a determination of the orbit

X-ray pulsations with a period of 9.3 s from the transient galactic X-ray source 2S 1553-542 were detected. The data were obtained with SAS 3 during the only known outburst of the source in 1975 June. Pulse-timing analyses of the data, which span an interval of 20 days, show that there were large changes in the pulse period that are readily attributable to binary orbital motion. The inferred orbital period is 30.6 + or - 2.2 days and the X-ray mass function is 5.0 + or - 2.1 solar masses. These orbital parameters, the transient nature of the source, and the probable lack of an early-type giant companion star, lead to the tentative conclusion that 2S 1553-542 is a Be/X-ray binary system.

A search for light-time effects in binary cepheids - AW Persei

view Abstract Citations (11) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A search for light-time effects in binary cepheids : AW Persei. Evans, N. R. Abstract Phase residuals in O-C diagrams for the classical Cepheid AW Persei have been examined to see whether they produce periodic variations associated with binary orbital motion (the light-time effect). Variations of several standard deviations in the O-C diagram are consistent with a light-time interpretation. The available radial velocity information is in agreement with the size and timing of the light curve shifts. An orbital period of 20 years is derived from recent radial velocities. Mass estimates from the orbit are discussed. Publication: The Astrophysical Journal Pub Date: September 1983 DOI: 10.1086/161281 Bibcode: 1983ApJ...272..214E Keywords: Astronomical Photometry; Binary Stars; Cepheid Variables; Light Curve; Phase Shift; Radial Velocity; Time Response; Astronomy full text sources ADS | data products SIMBAD (1)

Discovery of X-ray pulsations from 2S 1417-624

X-ray pulsations having a period of 17.64 sec are detected from the hard, variable galactic X-ray source 2S 1417-624. It is noted that the pulsations were found through a Fourier analysis of 40 satellite orbits of data taken with the rotation modulation collimators aboard SAS 3 in July 1978. The pulse profile shows detailed interpulse structure that is similar in character to the pulse profiles of 4U 0900-40 and A0535+26. Significant changes in pulse period are detected over the eight-day observing interval. It is suggested that these changes may be the result of a large intrinsic spin-up rate for the neutron star or from binary orbital motion, with orbital periods longer than approximately 15 days.

The slaved disc model for SS 433

We investigate a slaved disc model for SS 433 in which the beams originate normal to the surface of an accretion disc around a compact object in a binary system. The 13-day period in the ‘stationary’ system of lines is assumed to be associated with binary orbital motion and the 164-day periodicity in the moving line system is identified with disc precession. As in the slaved disc model for Her X-1, we assume that material is processed through the disc rapidly (relative to 164 days) so that the disc precesses at the same rate as the spin axis of the secondary which is driven by the gravitational torque applied by the compact object. If the secondary star does not underfill its critical lobe then the apparent absence of X-ray or optical eclipsing and beam interruption by the secondary places severe constraints on the model. We show that the viability of the basic model requires that the mass of the compact object be ≳ 10 times the mass of the secondary. Thus if the slaved disc model is applicable to SS 433 and if the mass of the secondary is ≳ 1 M⊙ it follows that the compact object is a massive black hole.

A new gravitational redshift for the white dwarf Omicron/2/ ERI B

view Abstract Citations (21) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A new gravitational redshift for the white dwarf omi2 ERI B. Wegner, G. Abstract Differential measurements of the radial velocities of the DA white dwarf Omicron(2) Eri B and its M4V3 companion, Omicron(2) Eri C, using the coude spectrograph of the 100-in. Mount Wilson telescope, yield a new gravitational redshift of V(RS) = +23.9 + or - 1.3 (s.d.) km/s. Corrections for the binary's orbital motion, the small gravitational redshift of the nondegenerate companion, and atmospheric refraction have been included in the reduction. At the present level of accuracy, the redshift, mass, and radius are inconsistent, but reconsideration of the errors and a slight lowering of the parallax to pi = +0.204 + or - 0.006 arcsec (s.d.) partially removes this problem. The radius is more insensitive to the parallax than the mass in the redshift-radius diagram. After a re-discussion of the radius, a value of 100R/solar radius = 1.30 + or - 0.03 is found. Using this, the position of Omicron(2) Eri B seems to agree with the Hamada and Salpeter mass-radius relations and stellar evolutionary theory, which predicts a carbon-oxygen core. The possibility of an iron core for Omicron(2) Eri B now seems doubtful. Publication: The Astronomical Journal Pub Date: September 1980 DOI: 10.1086/112792 Bibcode: 1980AJ.....85.1255W Keywords: Radial Velocity; Red Shift; Stellar Gravitation; Stellar Rotation; Stellar Spectra; White Dwarf Stars; Astrometry; Emission Spectra; H Alpha Line; Radii; Stellar Mass; Astrophysics full text sources ADS | data products SIMBAD (1)

The gravitational redshift of the white dwarf Omicron-2 ERI B

view Abstract Citations (12) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The gravitational redshift of the white dwarf omicron 2Eri B. Wegner, G. Abstract Measurements of ten spectrograms of the white dwarf O2 Eri B yield a new gravitational redshift RS = t 20+3 km s', after correction for the binary's orbital motion. This latter correction was determined from the dMe companion's radial velocity, which indicates that component B is presently receding from the Sun. Available data indicate that the best value for the radius is R /R0 =0.0137+0.0014, and Heintz's [Astron. J. 79, 819 (1974)] binary mass was adopted. Assuming that general relativity is correct, the observed values of V RS' R/R0 , and M/M0 agree with the predictions of the theoretical mass-radius relations of Hamada and Salpeter [Astrophys. J. 134, 683 (1961)] for white dwarfs composed of He, C, or Mg, but are not accurate enough to exclude Fe. Alternately, the observed redshift and that predicted by general relativity using R /R0 and M /M o. agree within the observa- tional errors of about + 10%. Publication: The Astronomical Journal Pub Date: May 1979 DOI: 10.1086/112463 Bibcode: 1979AJ.....84..650W Keywords: Gravitational Effects; Red Shift; White Dwarf Stars; Atmospheric Models; Relativity; Stellar Atmospheres; Stellar Models; Astrophysics; Gravitational Redshifts:White Dwarfs full text sources ADS | data products SIMBAD (1)

V1500 CYGNI: THE 3.35-HOUR 1978 LIGHT CURVE AND THE QUESTION OF A DOUBLE PERIOD.

ABSTRACT For this extraordinary postnova, based on 336 measures on 29 nights in August-October 1978, we find a peak-to-peak photometric variation in unfiltered light of 0.35 magnitude for the well-known 3.35-hour periodicity. Our period of 0.139617 ± 0.000005 day, obtained by a power-spectrum method, agrees with Patterson's determinations for both 1977 and 1978, which he found from the minima timings. In the variable light-curve shape and amplitude the period has clearly stabilized and undoubtedly reflects the binary orbital motion. A search for the long-surmised "double" period of 6.7 hours is described. Our mean light curve for the three-month interval shows no evidence, within quite small statistical fluctuations (Δm ≤ 0.03), for the double period. While a double-period process (conceivably the true orbital period) cannot be totally ruled out as yet, it seems more likely now that the apparent double light curves seen in limited time intervals can be attributed to random or quasi-random effects on a time scale of one to several days, e.g., changes in the shape of the envelope around the binary nucleus.

Discovery of a 7.68 second X-ray periodicity in 3U 1626-67

SAS-3 observations of the X-ray source 3U 1626-67 have revealed the presence of a stable 7.68-sec pulse period. This source was selected for study because of its hard X-ray spectrum. The compilation of source spectra used in the selection process is also presented. Pulse arrival times are analyzed for effects of possible binary orbital motion. Upper limits to the projected orbital radius are obtained which tend to exclude orbital periods in the range from about 0.5 to 35 days. Binary systems with either a very long orbit (at least 175 days) or a very short orbit (no more than about 0.3 day) are most probable