scholarly journals Secular changes in the orbits of the quadruple system VW LMi

2020 ◽  
Vol 494 (1) ◽  
pp. 178-189 ◽  
Author(s):  
T Pribulla ◽  
E Puha ◽  
T Borkovits ◽  
J Budaj ◽  
Z Garai ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Apsidal Motion ◽  
Centre Of Mass ◽  
Orbital Elements ◽  
Eclipsing Binary ◽  
Secular Changes ◽  
Quadruple System ◽  
Timing Data ◽  
Mutual Inclination

ABSTRACT VW LMi is the tightest known quadruple system with 2 + 2 hierarchy. It consists of a W UMa-type eclipsing binary (P12 = 0.477 55 d) and another detached non-eclipsing binary (P34 = 7.93 d) orbiting around a common centre of mass in about P1234 = 355 d. We present new observations of the system extending the time baseline to study long-term perturbations in the system and to improve orbital elements. The multidataset modelling of the system (four radial-velocity curves for the components and the timing data) clearly showed an apsidal motion in the non-eclipsing binary at a rate of 4.6 deg yr−1, but no other perturbations. This is consistent with the nearly co-planarity of the outer, 355-d orbit, and the 7.93-d orbit of the non-eclipsing binary. Extensive N-body simulations enabled us to constrain the mutual inclination of the non-eclipsing binary and the outer orbits to j34–1234 < 10 deg.

scholarly journals An estimate of the k2 Love number of WASP-18Ab from its radial velocity measurements

2019 ◽  
Vol 623 ◽  
pp. A45 ◽  
Author(s):  
Sz. Csizmadia ◽  
H. Hellard ◽  
A. M. S. Smith
Keyword(s):  
Radial Velocity ◽  
Spherical Shape ◽  
Model Fit ◽  
Interior Structure ◽  
Love Number ◽  
Central Mass ◽  
Tidal Interactions ◽  
Basic Model ◽  
Timing Data

Context. Increasing our knowledge of the interior structure, composition, and density distribution of exoplanets is crucial to make progress in the understanding of exoplanetary formation, migration and habitability. However, the directly measurable mass and radius values offer little constraint on interior structure, because the inverse problem is highly degenerate. Therefore, there is a clear need for a third observable of exoplanet interiors. This third observable can be the k2 fluid Love number which measures the central mass concentration of an exoplanet. Aims. The aims of this paper are (i) to develop a basic model to fit the long-term radial velocity and TTV variations caused by tidal interactions, (ii) to apply the model to the WASP-18Ab system, and (iii) to estimate the Love number of the planet. Methods. Archival radial velocity, transit and occultation timing data were collected and fitted using the model introduced here. Results. The best model fit to the archival radial velocity and timing data of WASP-18Ab was obtained with a Love number of the massive (~10 MJup) hot Jupiter WASP-18Ab: k2,Love = 0.62−0.19+0.55. This causes apsidal motion in the system, at a rate of ~0.0087 ± 0.0033°∕days ≊ 31.3 ± 11.8 arcsec day−1. When checking possible causes of periastron precession, other than the relativistic term or the non-spherical shape of the components, we found a companion star to the WASP-18 system, named WASP-18B which is a probable M6.5V dwarf with ~0.1 M⊙ at 3519 AU distance from the transit host star. We also find that small orbital eccentricities may be real, rather than an apparent effect caused by the non-spherical stellar shape.

scholarly journals The Eclipsing Triple System U Ophiuchi Revisited

2006 ◽  
Vol 2 (S240) ◽  
pp. 109-110
Author(s):  
Luiz Paulo R. Vaz ◽  
Johannes Andersen ◽  
Antônio Claret
Keyword(s):  
Radial Velocity ◽  
Triple System ◽  
Heavy Element ◽  
Main Sequence ◽  
Element Abundance ◽  
Apsidal Motion ◽  
Eclipsing Binary ◽  
The Third ◽  
Sequence Band ◽  
Nearby Stars

AbstractWe have redetermined the absolute dimensions of the mid B-type eclipsing binary U Oph from new light and radial-velocity curves, accounting for both the apsidal motion and the light-time orbit around the third star. The stars in U Oph have masses of 5.27 and 4.74 M⊙(±1.5%) and are located in the middle of the main-sequence band for an an age of ∼50 Myr. U Oph and three other systems (V760 Sco, MU, Cas and DI Her) all have components within 10% of 5M⊙ and ages below 100 Myr; we find significant heavy-element abundance differences between these young nearby stars.

Companion(s) of the Eclipsing Binary KIC 3832716

2017 ◽  
Vol 14 (S339) ◽  
pp. 331-334
Author(s):  
Š. Parimucha ◽  
M. Fedurco ◽  
P. Gajdoš
Keyword(s):  
Eclipsing Binaries ◽  
Secondary Component ◽  
Centre Of Mass ◽  
Mass Ratio ◽  
Time Effects ◽  
Eclipsing Binary ◽  
Long Term Changes ◽  
Different Types ◽  
Orbital Periods

AbstractDetailed analyses of observations by the Kepler satellite may reveal unknown facts about objects that were previously regarded as eclipsing binaries. We present results of our analysis of such an object, KIC 3832716. We show that the system actually contains two eclipsing binaries (EB1 and EB2), with orbital periods of 1.14 and 2.17 days, orbiting around their common centre of mass with period of at least 1400 days and with an estimated mass ratio of 0.7 ± 0.3. Analyses of the (O–C) diagrams of both eclipsing pairs show three different types of variation: (i) long-term changes probably due to light-time effects, (ii) spikes caused by the superposition of the eclipses of both binaries, and (iii) semi-regular variations in EB1 with a period of 57 days, presumably caused by the presence of spots on its secondary component.

scholarly journals V379 Cep: a System of Two Binaries

2006 ◽  
Vol 2 (S240) ◽  
pp. 499-502
Author(s):  
P. Mayer ◽  
P. Harmanec ◽  
H. Božić ◽  
P. Eenens ◽  
E.F. Guinan ◽  
...  
Keyword(s):  
Orbital Period ◽  
Electronic Spectra ◽  
Spectral Lines ◽  
Orbital Elements ◽  
Eclipsing Binary ◽  
Centre Of Gravity ◽  
Quadruple System ◽  
The Common

AbstractWe obtained new series of electronic spectra and UBV photometry of V379 Cep and analyzed them in an effort to check whether the conclusion about its anomalous masses is not premature. We found that the second system of spectral lines seen in the spectra of V379 Cep does not belong to the secondary but to the primary of another binary Ba+Bb (orbital period of 159d0) which constitutes a quadruple system with the narrow-lined 99d76 eclipsing binary Aa+Ab (for which we report probable detection of the secondary and derive improved period and orbital elements). The mutual motion of the two binaries A+B around the common centre of gravity is also observable and the probable orbital period is some 7878 days. Our result shows that the components Aa and Ba are somewhat evolved but removes the reported discrepancy of anomalously small masses. We find that V379 Cep is an astrophysically interesting quadruple system for which a future combination of interferometry, spectroscopy and photometry can provide individual masses of all four bodies.

scholarly journals The Solar-Type Eclipsing Binary System AI Phoenicis

1983 ◽  
Vol 71 ◽  
pp. 407-408
Author(s):  
E.F. Milone ◽  
B.J. Hrivnak
Keyword(s):  
Binary System ◽  
Radial Velocity ◽  
Orbital Elements ◽  
Primary Minimum ◽  
Eclipsing Binary ◽  
Solar Type ◽  
Solar Uv ◽  
Limb Darkening ◽  
Solar Type Star

AI Phe was discovered to be variable and identified as an EA binary by Strohmeier (1972). Reipurth (1978) subsequently carried out uvby photometry, determined the period (24.5923 d), and noted the lengthy totality of primary minimum and the displacement of the secondary minimum. Imbert (1978) obtained radial velocity curves and determined spectroscopic orbital elements. Imbert also gives a spectroscopic classification of G2V for the primary (hotter) component and approximately G5 for the secondary. AI Phe thus appeared to offer a unique opportunity to study the limb darkening of a non-interacting solar-type star. As an extension of a solar UV limb darkening study (Kjeldseth Moe and Milone 1978), ten IUE spectra were obtained on Aug. 12 in 2 successive shifts (cf Milone et al 1981). In conjunction with this, ground-based 5-colour photometry and spectroscopy were carried out at CTIO and at UTLCO.

scholarly journals Extended analytical formulae for the perturbed Keplerian motion under low-thrust acceleration and orbital perturbations

2021 ◽  
Vol 133 (3) ◽  
Author(s):  
Marilena Di Carlo ◽  
Simão da Graça Marto ◽  
Massimiliano Vasile
Keyword(s):  
Gravitational Perturbation ◽  
Low Thrust ◽  
Orbital Elements ◽  
Third Body ◽  
The Third ◽  
Orbital Perturbations ◽  
Analytical Formulae ◽  
Numerical Orbit ◽  
Body Potential

AbstractThis paper presents a collection of analytical formulae that can be used in the long-term propagation of the motion of a spacecraft subject to low-thrust acceleration and orbital perturbations. The paper considers accelerations due to: a low-thrust profile following an inverse square law, gravity perturbations due to the central body gravity field and the third-body gravitational perturbation. The analytical formulae are expressed in terms of non-singular equinoctial elements. The formulae for the third-body gravitational perturbation have been obtained starting from equations for the third-body potential already available in the literature. However, the final analytical formulae for the variation of the equinoctial orbital elements are a novel derivation. The results are validated, for different orbital regimes, using high-precision numerical orbit propagators.

scholarly journals R Coronae Borealis Stars: Long-Term Photometric & Spectroscopic Studies

1998 ◽  
Vol 11 (1) ◽  
pp. 379-379
Author(s):  
P.L. Cottrell ◽  
L. Skuljan ◽  
P.M. Kilmartin ◽  
C. Gilmore ◽  
W.A. Lawson
Keyword(s):  
Radial Velocity ◽  
Spectroscopic Studies ◽  
Photometric Data ◽  
Decline Phase ◽  
Dust Clouds ◽  
Medium Resolution ◽  
Formation And Evolution ◽  
R Coronae Borealis Stars ◽  
Insight Into

For more than a decade we have been able to acquire and analyse a significant amount of photometric data of the highly variable R Coronae Borealis (RCB) stars. This has made been possible by a photometric service observing programme instigated at the Observatory. These photometric data have been combined with less extensive spectroscopic coverage, particularly of the decline phase of these stars. These have been supplemented by observations obtained at Mount Stromlo and Siding Spring Observatories for a radial velocity study. Significantly more spectroscopic observations are now being acquired with the development of a new medium resolution spectrograph at Mount John University Observatory. In this poster we will present recent photometric and spectroscopic results for a number of the RCB stars in our sample. This observational and analysis work can be used to provide further insight into the nature of these stars, their likely progeny and progenitors and the processes that are involved in the formation and evolution of the obscuring dust clouds which cause the decline phase.

scholarly journals Ensemble Pulsar Time Study by Pulsar Timing Observations

2004 ◽  
Vol 218 ◽  
pp. 439-440
Author(s):  
Tinggao Yang ◽  
Guangren Ni
Keyword(s):  
Time Scale ◽  
Wavelet Decomposition ◽  
Time Study ◽  
Millisecond Pulsar ◽  
Millisecond Pulsars ◽  
Pulsar Time ◽  
Pulsar Timing ◽  
Timing Data ◽  
Gravitational Wave Background

Long term timing of multiple millisecond pulsars can contribute to the study of an ensemble pulsar time scale PTens. A wavelet decomposition algorithm (WDA) was applied to define a PTens using the available millisecond pulsar timing datA. The PTens obtained from WDA is more stable than those resulting from other algorithms. The Chinese 50 m radio telescope is specially designed for PTens study and detection of gravitational wave background via millisecond pulsars timing observations. A scheme for multiple millisecond pulsar timing and ensemble pulsar time study is discussed in some detail.

scholarly journals Long-Term Coudé Radial-Velocity Studies With a 1.2-m Telescope

2001 ◽  
Vol 183 ◽  
pp. 283-288
Author(s):  
C.D. Scarfe
Keyword(s):  
Radial Velocity ◽  
Binary Stars ◽  
Star System ◽  
Standard Star ◽  
Stellar Spectra ◽  
Multiple Stars ◽  
Binary And Multiple Stars ◽  
Selection Of

AbstractI have used the 1.2-m telescope and coudé spectrograph of the Dominion Astrophysical Observatory for more than 30 years in a program of radial-velocity observations of binary stars. The program was begun with photographic plates as detectors, but for 20 years the primary detector has been the radial-velocity scanner, which cross-correlates stellar spectra with an artificial mask.Since some of the binaries under observation have periods of several years, the instrument’s stability is an important consideration. I have therefore been obliged to observe standard stars and asteroids to check its performance. These observations are of relevance to efforts to improve the IAU standard star system.I will describe the telescope, spectrograph and scanner, and will briefly discuss some of the results obtained for a selection of binary and multiple stars.

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