A search for rapid photometric variability in symbiotic binaries

AbstractThe photometric variability of CPD-48°1577 in the optical and IR ranges is discussed. The structure and variation of prominent emission line profiles are investigated. An estimate of the distance is given.

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Learning about Stellar Dynamos from Long–term Photometry of Starspots

International Astronomical Union Colloquium ◽

10.1017/s0252921100079914 ◽

1991 ◽

Vol 130 ◽

pp. 353-369 ◽

Cited By ~ 2

Author(s):

Douglas S. Hall

Keyword(s):

Differential Rotation ◽

Rotation Period ◽

Turnover Time ◽

Rotating Stars ◽

Photometric Variability ◽

Solar Type ◽

Magnetic Cycles ◽

The Many ◽

Rapidly Rotating Stars

AbstractSpottedness, as evidenced by photometric variability in 277 late-type binary and single stars, is found to occur when the Rossby number is less than about 2/3. This holds true when the convective turnover time versus B–V relation of Gilliland is used for dwarfs and also for subgiants and giants if their turnover times are twice and four times longer, respectively, than for dwarfs. Differential rotation is found correlated with rotation period (rapidly rotating stars approaching solid-body rotation) and also with lobe-filling factor (the differential rotation coefficient k is 2.5 times larger for F = 0 than F = 1). Also reviewed are latitude extent of spottedness, latitude drift during a solar-type cycle, sector structure and preferential longitudes, starspot lifetimes, and the many observational manifestations of magnetic cycles.

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Rapid Photometric Variability Of The Symbiotic System CH Cyg During 2008–15

EAS Publications Series ◽

10.1051/eas/1571021 ◽

2015 ◽

Vol 71-72 ◽

pp. 107-108

Author(s):

S. Shugarov ◽

A. Skopal ◽

M. Sekeráš ◽

G. Komissarova ◽

M. Wolf

Keyword(s):

Symbiotic System ◽

Photometric Variability

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Long-Term Multicolour Photometry of the Young Stellar Objects FHO 26, FHO 27, FHO 28, FHO 29, and V1929 Cygni

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2015.21 ◽

2015 ◽

Vol 32 ◽

Cited By ~ 9

Author(s):

S. I. Ibryamov ◽

E. H. Semkov ◽

S. P. Peneva

Keyword(s):

Gulf Of Mexico ◽

Young Stellar Objects ◽

Main Sequence Stars ◽

Stellar Objects ◽

Photometric Variability ◽

The North ◽

Dense Molecular Cloud ◽

Photometric Observations ◽

All Optical

AbstractResults from long-term multicolour optical photometric observations of the pre-main-sequence stars FHO 26, FHO 27, FHO 28, FHO 29, and V1929 Cyg collected during the period from 1997 June to 2014 December are presented. The objects are located in the dense molecular cloud L935, named ‘Gulf of Mexico’, in the field between the North America and Pelican nebulae. All stars from our study exhibit strong photometric variability in all optical passbands. Using our BVRI observations and data published by other authors, we tried to define the reasons for the observed brightness variations. The presented paper is a part of our long-term photometric study of the young stellar objects in the region of ‘Gulf of Mexico’.

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3D Models of Symbiotic Binaries

EAS Publications Series ◽

10.1051/eas/1571015 ◽

2015 ◽

Vol 71-72 ◽

pp. 81-86

Author(s):

S. Mohamed ◽

R. Booth ◽

Ph. Podsiadlowski ◽

S. Ramstedt ◽

W. Vlemmings ◽

...

Keyword(s):

3D Models ◽

Symbiotic Binaries

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Astrometric and Photometric Variability in Quasars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310005648 ◽

2009 ◽

Vol 5 (S267) ◽

pp. 103-103

Author(s):

A. H. Andrei ◽

S. Bouquillon ◽

J. L. Penna ◽

F. Taris ◽

S. Anton ◽

...

Keyword(s):

Strong Support ◽

Optical Emission ◽

Optical Observations ◽

Massive Black Hole ◽

Full Account ◽

Photometric Variability ◽

Central Engine ◽

Relationship Of ◽

The Relationship

Quasars are the choicest objects to define a quasi-inertial reference frame. At the same time, they are active galactic nuclei powered by a massive black hole. As the astrometric precision of ground-based optical observations approaches the limit set by the forthcoming GAIA mission, astrometric stability can be investigated. Though the optical emission from the core region usually exceeds the other components by a factor of a hundred, the variability of those components must surely imply some measure of variability of the astrometric baricenter. Whether this is confirmed or not, it puts important constraints on the relationship of the quasar's central engine to the surrounding distribution of matter. To investigate the correlation between long-term optical variability and what is dubbed as the “random walk” of the astrometric center, a program is being pursued at the WFI/ESO 2.2m. The sample was selected from quasars known to undergo large-amplitude and long-term optical variations (Smith et al. 1993; Teerikorpi 2000). The observations are typically made every two months. The treatment is differential, comparing the quasar position and brightness against a sample of selected stars for which the average relative distances and magnitudes remain constant. The provisional results for four objects bring strong support to the hypothesis of a relationship between astrometric and photometric variability. A full account is provided by Andrei et al. (2009).

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BINARY CENTRAL STARS OF PLANETARY NEBULAE DISCOVERED THROUGH PHOTOMETRIC VARIABILITY. IV. THE CENTRAL STARS OF HaTr 4 AND Hf 2-2

The Astronomical Journal ◽

10.3847/0004-6256/152/2/34 ◽

2016 ◽

Vol 152 (2) ◽

pp. 34 ◽

Cited By ~ 16

Author(s):

Todd C. Hillwig ◽

Howard E. Bond ◽

David J. Frew ◽

S. C. Schaub ◽

Eva H. L. Bodman

Keyword(s):

Planetary Nebulae ◽

Photometric Variability ◽

Central Stars

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Photometric detection of internal gravity waves in upper main-sequence stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038224 ◽

2020 ◽

Vol 640 ◽

pp. A36 ◽

Cited By ~ 5

Author(s):

D. M. Bowman ◽

S. Burssens ◽

S. Simón-Díaz ◽

P. V. F. Edelmann ◽

T. M. Rogers ◽

...

Keyword(s):

Gravity Waves ◽

Massive Stars ◽

Pressure Fluctuations ◽

Tangential Velocity ◽

Chemical Species ◽

Internal Gravity Waves ◽

Spectral Lines ◽

Photometric Variability ◽

Near Surface ◽

Photometric Detection

Context. Massive stars are predicted to excite internal gravity waves (IGWs) by turbulent core convection and from turbulent pressure fluctuations in their near-surface layers. These IGWs are extremely efficient at transporting angular momentum and chemical species within stellar interiors, but they remain largely unconstrained observationally. Aims. We aim to characterise the photometric detection of IGWs across a large number of O and early-B stars in the Hertzsprung–Russell diagram, and explain the ubiquitous detection of stochastic variability in the photospheres of massive stars. Methods. We combined high-precision time-series photometry from the NASA Transiting Exoplanet Survey Satellite with high-resolution ground-based spectroscopy of 70 stars with spectral types O and B to probe the relationship between the photometric signatures of IGWs and parameters such as spectroscopic mass, luminosity, and macroturbulence. Results. A relationship is found between the location of a star in the spectroscopic Hertzsprung–Russell diagram and the amplitudes and frequencies of stochastic photometric variability in the light curves of massive stars. Furthermore, the properties of the stochastic variability are statistically correlated with macroturbulent velocity broadening in the spectral lines of massive stars. Conclusions. The common ensemble morphology for the stochastic low-frequency variability detected in space photometry and its relationship to macroturbulence is strong evidence for IGWs in massive stars, since these types of waves are unique in providing the dominant tangential velocity field required to explain the observed spectroscopy.

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