IR Geminorum: Complex Disk Behavior During Quiescence

International Astronomical Union Colloquium ◽

10.1017/s0252921100008861 ◽

2004 ◽

Vol 191 ◽

pp. 259-262

Author(s):

Zongyun Li ◽

Kam-Ching Leung ◽

C. Martin Gaskell

Keyword(s):

Orbital Period ◽

V Band ◽

Eccentric Disk ◽

Nearly Continuous ◽

Periodic Cycles

AbstractWe have carried out nearly continuous V-band photometry from Yunnan Observatory (China) and Behlen Observatory (Nebraska, USA) of IR Gem for over six days starting three days after a normal outburst in January 2002. Our observations show that the behavior of this SU UMa star is unexpectedly complicated, and that for IR Gem, quiescence is potentially more interesting than outbursts. We find a photometric modulation with a period of 98.5 min, exactly equal to the spectroscopically determined orbital period. We tentatively attribute this to heating of the secondary. During the first three days a modulation appeared with a period 5% longer than the orbital period. We suggest that this might be a signature of apsidal precession of an eccentric disk. During the middle of our period of observations a modulation with a period 3% shorter than the orbital period appeared. We invoke nodal precession to explain this. A slower modulation we found with a period of about 1.7 d is roughly consistent with the expected period of nodal precession. There is a puzzling 4.3 d period modulation that we suspect may be the result of beating between apsidal and nodal precession frequencies. We also find inexplicable quasi-periodic cycles on timescales drifting from ~ 0.2 to ~ 0.4 days.

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MOST Spacebased Photometry of HD 189733: Precise Timing Measurements for Transits Across an Active Star

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308026938 ◽

2008 ◽

Vol 4 (S253) ◽

pp. 459-461

Author(s):

E. Miller-Ricci ◽

J. F. Rowe ◽

D. Sasselov ◽

J. M. Matthews ◽

R. Kuschnig ◽

...

Keyword(s):

Orbital Period ◽

Mass Range ◽

Active Star ◽

Precise Timing ◽

Resonant Orbits ◽

The Earth ◽

Test Spot ◽

Transit Times ◽

Nearly Continuous ◽

Parent Star

AbstractWe have measured transit times for HD 189733 passing in front of its bright (V = 7.67) chromospherically active and spotted parent star. Nearly continuous broadband photometry of this system was obtained with the MOST (Microvariability & Oscillations of STars) space telesope during 21 days in August 2006, monitoring 10 consecutive transits. We have used these data to search for deviations from a constant orbital period which can indicate the presence of additional planets in the system that are as yet undetected by Doppler searches. We find no variations above the level of ±45 s, ruling out planets in the Earth-to-Neptune mass range in a number of resonant orbits. We find that a number of complications can arise in measuring transit times for a planet transiting an active star with large star spots. However, such transiting systems are also useful in that they can help to constrain and test spot models. This has implications for the large number of transiting systems expected to be discovered by the CoRoT and Kepler missions.

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New MOST Photometry of the 55 Cancri System

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313012520 ◽

2012 ◽

Vol 8 (S293) ◽

pp. 52-57 ◽

Cited By ~ 2

Author(s):

Diana Dragomir ◽

Jaymie M. Matthews ◽

Joshua N. Winn ◽

Jason F. Rowe ◽

Keyword(s):

Orbital Period ◽

Phase Variation ◽

Cnc System ◽

Data Set ◽

Upper Limit ◽

Nearly Continuous ◽

Geometric Albedo

AbstractSince the discovery of its transiting nature, the super-Earth 55 Cnc e has become one of the most enthusiastically studied exoplanets, having been observed spectroscopically and photometrically, in the ultraviolet, optical and infrared regimes. To this rapidly growing data set, we contribute 42 days of new, nearly continuous MOST photometry of the 55 Cnc system. Our analysis of these observations together with the discovery photometry obtained in 2011 allows us to determine the planetary radius (1.990+0.084−0.080) and orbital period (0.7365417+0.0000025−0.0000028) of 55 Cnc e with unprecedented precision. We also followed up on the out-of-transit phase variation first observed in the 2011 photometry, and set an upper limit on the depth of the planet's secondary eclipse, leading to an upper limit on its geometric albedo of 0.6.

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The active RS CVn-type system SZ Pictoris

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3025 ◽

2019 ◽

Vol 490 (4) ◽

pp. 5832-5838

Author(s):

C I Martínez ◽

J F González ◽

A Buccino ◽

R Ibañez Bustos ◽

P J D Mauas

Keyword(s):

Orbital Period ◽

Type System ◽

Short Term ◽

Cyclic Activity ◽

Similar Time ◽

Orbital Parameters ◽

Secondary Star ◽

V Band ◽

Composite Spectra

ABSTRACT We study the short-term variability and long-term variability of the spectroscopic binary SZ Pictoris, a southern RS CVn-type system. We used mid-resolution Echelle spectra obtained at Complejo Astronómico El Leoncito spanning 18 yr, and the photometric data from the All Sky Automated Survey data base (V band) and from the Optical Robotic Observatory (BVRI bands) for similar time lapses. We separated the composite spectra into those corresponding to both components, and we were able to determine accurate orbital parameters, in particular an orbital period of 4.95 d. We also observed a photometric modulation with half the orbital period, due to the ellipticity of the stars. We also found cyclic activity with a period of ∼2030 d, both in the photometry and in the Ca ii flux of the secondary star of the system.

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Comprehensive study of a neglected contact binary TYC 5532-1333-1

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa031 ◽

2020 ◽

Vol 493 (2) ◽

pp. 1565-1573

Author(s):

S P Devarapalli ◽

R Jagirdar ◽

R M Prasad ◽

V S Thomas ◽

S A Ahmed ◽

...

Keyword(s):

Orbital Period ◽

Period Variation ◽

Third Body ◽

Mutual Correlation ◽

V Band ◽

Angular Momentum Loss ◽

Contact Binary ◽

First Time ◽

Comprehensive Study

ABSTRACT A comprehensive photometric and spectroscopic analysis of the variable TYC 5532-1333-1 (TYC) along with an investigation of its orbital period variation is presented for the first time. The B- and V-band photometric study indicates that TYC is an intermediate contact binary with degree of contact and mass ratio of 34 per cent and ∼0.24, respectively. The derived equivalent widths from the spectroscopic study of Hα and Na-I lines reveal phase-dependent variation and mutual correlation. Using the available times of minimum light, an investigation of orbital period variation shows a long-term decrease at a rate of 3.98 × 10 −6 d yr−1. Expected causes for such decline in the orbital period could be angular momentum loss and a quasi-sinusoidal variation due to light-time effect probably caused by a third-body companion. The minimum mass of the third body (M3) was derived to be $0.65 \, \mathrm{M}_{\odot }$. Our presented study is an attempt to evaluate and understand the evolutionary state of above-mentioned neglected contact binary.

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SPH Simulations of Tidally Unstable Accretion Disks

International Astronomical Union Colloquium ◽

10.1017/s0252921100038380 ◽

1996 ◽

Vol 158 ◽

pp. 115-116

Author(s):

James Murray

Keyword(s):

Accretion Disks ◽

Orbital Period ◽

Smoothed Particle Hydrodynamics ◽

Inertial Frame ◽

Feedback Mechanism ◽

Mode Analysis ◽

Two Dimensional ◽

Particle Hydrodynamics ◽

Smoothed Particle ◽

Eccentric Disk

We use two dimensional Smoothed Particle Hydrodynamics simulations to investigate the the Tidal Resonance Instability (TRI) model for superhumps in SU UMa stars.In the TRI model, superhumps are the signature of an eccentric disk being periodically stressed by the binary system’s rotating tidal field. A slow prograde motion of the disk in the inertial frame is then responsible for the superhump period slightly exceeding the binary orbital period. The disk eccentricity is caused by a 3:1 resonance between orbits in the disk and the orbit of the binary itself. The development of the TRI model is due mainly to Whitehurst (1988), Hirose & Osaki (1990) and Lubow (1991a). Lubow in particular carried out a nonlinear mode analysis of a fluid disk’s response to a weak tidal field and identified the feedback mechanism responsible for disk eccentricity growth.

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Mid-Cycle Observations of CR Boo and Estimation of the System’s Parameters

Data ◽

10.3390/data5040113 ◽

2020 ◽

Vol 5 (4) ◽

pp. 113

Author(s):

Daniela Boneva ◽

Svetlana Boeva ◽

Yanko Nikolov ◽

Zorica Cvetković ◽

Radoslav Zamanov

Keyword(s):

Binary System ◽

Observational Data ◽

Orbital Period ◽

Binary Star ◽

Contact Point ◽

Bright Spot ◽

V Band ◽

Phase Rotation

We present observations (with NAO Rozhen and AS Vidojevica telescopes) of the AM Canum Venaticorum (AM CVn) binary star CR Bootis (CR Boo) in the UBV bands. The data were obtained in two nights in July 2019, when the V band brightness was in the range of 16.1–17.0 mag. In both nights, a variability for a period of 25 ± 1 min and amplitude of about 0.2 magnitudes was visible. These brightness variations are most likely indications of “humps”. During our observational time, they appear for a period similar to the CR Boo orbital period. A possible reason of their origin is the phase rotation of the bright spot, placed in the contact point of the infalling matter and the outer disc edge. We estimated some of the parameters of the binary system, on the base of the observational data.

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Investigation of the Eclipsing Binary AN Tauri

Symposium - International Astronomical Union ◽

10.1017/s0074180900122387 ◽

1992 ◽

Vol 151 ◽

pp. 321-324

Author(s):

J.M. Kreiner ◽

J. Krzesinski ◽

G. Pajdosz ◽

J. Tremko ◽

S. Zoła

Keyword(s):

Light Curve ◽

Orbital Period ◽

Physical Parameters ◽

Eclipsing Binary ◽

V Band ◽

New Period ◽

Type Variable ◽

Visual Light

AN Tau has been classified as the β Lyrae-type variable. The only visual light curve was published 55 years ago. The star was observed photoelectrically during a few last years at Mt. Suhora and Skalnaté Pleso Observatories. The complete light curve was obtained in B and V band passes. The preliminary physical parameters of the system were obtained using the Wilson-Devinney code. From the period study of AN Tau we derived new period of the system being 1d.6143843, which differs by 0d.00026 from the value obtained earlier. The orbital period of AN Tau seems to be constant.

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The Eclipsing Binary WX Eridani

International Astronomical Union Colloquium ◽

10.1017/s0252921100073656 ◽

1979 ◽

Vol 46 ◽

pp. 385

Author(s):

M.B.K. Sarma ◽

K.D. Abhankar

Keyword(s):

Light Curve ◽

Spectral Type ◽

Orbital Period ◽

Primary Component ◽

Light Curves ◽

Absorption Feature ◽

Primary Star ◽

Eclipsing Binary ◽

The Times ◽

Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

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RSCVn Stars in the Southern Hemisphere

International Astronomical Union Colloquium ◽

10.1017/s0252921100073644 ◽

1979 ◽

Vol 46 ◽

pp. 371-384 ◽

Cited By ~ 3

Author(s):

J.B. Hearnshaw

Keyword(s):

Light Curve ◽

Southern Hemisphere ◽

Orbital Period ◽

Binary Stars ◽

Small Amplitude ◽

Light Variation ◽

Orbital Phase

RSCVn stars are fully detached binary stars which show intrinsic small amplitude (up to 0.3 amplitude peak-to-peak) light variations, as well as, in most of the known cases, eclipses. The spectra are F to G, IV to V for the hotter component and usually KOIV for the cooler. They are also characterised by abnormally strong H and K emission from the cooler star, or, occasionally, from both components. The orbital and light curve periods are in the range 1 day to 2 weeks. An interesting feature is the migration of the light variations to earlier orbital phase, as the light variation period is shorter than the orbital period by a few parts in 10+4to a few parts in 10+3.

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