scholarly journals Improved model of the triple system V746 Cassiopeiae that has a bipolar magnetic field associated with the tertiary

2017 ◽  
Vol 609 ◽  
pp. A5
Author(s):  
P. Harmanec ◽  
M. Brož ◽  
P. Mayer ◽  
P. Zasche ◽  
L. Kotková ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Triple System ◽  
Detection Threshold ◽  
Variable Magnetic Field ◽  
Close Binary ◽  
Rotational Period ◽  
Orbital Inclination ◽  
Photometric Observations ◽  
Optical Region ◽  
Improved Model

V746 Cas is known to be a triple system composed of a close binary with an alternatively reported period of either 25\hbox{$.\!\!^{\rm d}$}4 or 27\hbox{$.\!\!^{\rm d}$}8 and a distant third component in a 170 yr (62 000 d) orbit. The object was also reported to exhibit multiperiodic light variations with periods from 0\hbox{$.\!\!^{\rm d}$}83 to 2\hbox{$.\!\!^{\rm d}$}50, on the basis of which it was classified as a slowly pulsating B star. Interest in further investigation of this system was raised by the recent detection of a variable magnetic field. Analysing spectra from four instruments, earlier published radial velocities, and several sets of photometric observations, we arrived at the following conclusions: (1) The optical spectrum is dominated by the lines of the B-type primary (Teff 1 ~ 16 500(100) K), contributing 70% of the light in the optical region, and a slightly cooler B tertiary (Teff 3 ~ 13 620(150) K). The lines of the low-mass secondary are below our detection threshold; we estimate that it could be a normal A or F star. (2) We resolved the ambiguity in the value of the inner binary period and arrived at a linear ephemeris of \hbox{$T_{\rm super.\,conj.}={\rm HJD}~2\,443\,838.78(81)+25\fd41569(42)\times E$}. (3) The intensity of the magnetic field undergoes a sinusoidal variation in phase with one of the known photometric periods, namely 2\hbox{$.\!\!^{\rm d}$}503867(19), which we identify with the rotational period of the tertiary. (4) The second dominant photometric 1\hbox{$.\!\!^{\rm d}$}0649524(40) period is tentatively identified with the rotational period of the broad-lined B-type primary, but this interpretation is much less certain and needs further verification. (5) If our interpretation of photometric periods is confirmed, the classification of the object as a slowly pulsating B star should be revised. (6) Applying an N-body model to different types of available observational data, we can constrain the orbital inclination of the inner orbit to ~60°<i1< 85° even in the absence of binary eclipses, and we estimate the probable properties of the triple system and its components.

A Spectroscopic and Photometric Study of 1H0542-407: A New Magnetic Variable

1987 ◽  
Vol 7 (2) ◽  
pp. 151-158
Author(s):  
D. A. H. Buckley ◽  
I. R. Tuohy
Keyword(s):  
Magnetic Field ◽  
White Dwarf ◽  
Rotation Period ◽  
Mass Function ◽  
X Rays ◽  
Orbital Inclination ◽  
Medium Resolution ◽  
Photometric Observations ◽  
Short Period ◽  
Velocity Variations

AbstractWe report spectroscopic and photometric observations of the new DQ Hercuis system 1H0542-407, recently discovered by us to be the optical counterpart of a HEAO-1 X-ray source. Medium resolution spectroscopy using the AAT in the region λ3930 to λ4960 conducted over consecutive nights shows radial velocity variations at periods of ∼ 1910 s, consistent with the white dwarf rotation period, and 5.7 h, in agreement with the orbital period derived from our EXOSAT observations. The K semi-amplitude velocities are ∼ 50 and 20 km s-1 respectively, leading to a mass function f(M) = 3.3 ± 0.6 × 10-3M⊙ and an orbital inclination close to 20°. The emission line profiles are characterized by simple Gaussians whose FWHM vary at the rotation period. A time series analysis of high resolution photometry conducted on the ANU 2.3 metre telescope reveals the presence of several periodicities, including the orbital sidebands. The dominant sideband (Vr − Vo) arises from X-rays reprocessed in a region corotating at the orbital frequency. A model is developed for 1H0542-407 which indicates that the accretion disk is disrupted at ∼5Rwd by the primary’s magnetic field. The short period velocity variations arise within the magnetosphere. A white dwarf magnetic field strength of < ∼ 3 MG is implied.

scholarly journals New approach to describe two coupled spins in a variable magnetic field

2021 ◽  
Author(s):  
Yury Belousov ◽  
Roberto Grimaudo ◽  
Antonino Messina ◽  
Agostino Migliore ◽  
Alessandro Sergi
Keyword(s):  
Magnetic Field ◽  
Variable Magnetic Field ◽  
New Approach

Polarimetric and photometric observations of CB54, with analysis of four other dark clouds

2021 ◽  
Vol 503 (4) ◽  
pp. 5274-5290
Author(s):  
A K Sen ◽  
V B Il’in ◽  
M S Prokopjeva ◽  
R Gupta
Keyword(s):  
Magnetic Field ◽  
Near Infrared ◽  
Galactic Plane ◽  
Photometric Data ◽  
Dust Particles ◽  
Dark Cloud ◽  
Dark Clouds ◽  
High Polarization ◽  
Field Parallel ◽  
Photometric Observations

ABSTRACT We present the results of our BVR-band photometric and R-band polarimetric observations of ∼40 stars in the periphery of the dark cloud CB54. From different photometric data, we estimate E(B − V) and E(J − H). After involving data from other sources, we discuss the extinction variations towards CB54. We reveal two main dust layers: a foreground, E(B − V) ≈ 0.1 mag, at ∼200 pc and an extended layer, $E(B-V) \gtrsim 0.3$ mag, at ∼1.5 kpc. CB54 belongs to the latter. Based on these results, we consider the reason for the random polarization map that we have observed for CB54. We find that the foreground is characterized by low polarization ($P \lesssim 0.5$ per cent) and a magnetic field parallel to the Galactic plane. The extended layer shows high polarization (P up to 5–7 per cent). We suggest that the field in this layer is nearly perpendicular to the Galactic plane and both layers are essentially inhomogeneous. This allows us to explain the randomness of polarization vectors around CB54 generally. The data – primarily observed by us in this work for CB54, by A. K. Sen and colleagues in previous works for three dark clouds CB3, CB25 and CB39, and by other authors for a region including the B1 cloud – are analysed to explore any correlation between polarization, the near-infrared, E(J − H), and optical, E(B − V), excesses, and the distance to the background stars. If polarization and extinction are caused by the same set of dust particles, we should expect good correlations. However, we find that, for all the clouds, the correlations are not strong.

scholarly journals The Magnetic Be Star Sigma Orionis E

1987 ◽  
Vol 92 ◽  
pp. 82-83 ◽  
Author(s):  
C. T. Bolton ◽  
A. W. Fullerton ◽  
D. Bohlender ◽  
J. D. Landstreet ◽  
D. R. Gies
Keyword(s):  
Magnetic Field ◽  
Field Structure ◽  
High Signal ◽  
Rotational Period ◽  
Magnetic Field Structure ◽  
The Past ◽  
Distribution Of Elements ◽  
Be Star ◽  
Hα Emission ◽  
The Magnetic Field

Over the past two years, we have obtained high resolution high signal/noise (S/N) spectra of the magnetic Be star σ Ori E at the Canada-France-Hawaii Telescope and McDonald Observatory. These spectra, which cover the spectral regions 399-417.5 and 440-458.5 nm and the Hα line and have typical S/N>200 and spectral resolution ≃0.02 nm, were obtained at a variety of rotational phases in order to study the magnetic field structure, the distribution of elements in the photosphere, and the effects of the magnetic field on the emission envelope. Our analysis of these spectra confirms, refines and extends the results obtained by Landstreet & Borra (1978), Groote & Hunger (1982 and references therein), and Nakajima (1985).The Hα emission is usually double-peaked, but it undergoes remarkable variations with the 1.19081 d rotational period of the star, which show that the emitting gas is localized into two regions which co-rotate with the star.

scholarly journals Fast Drift-Scan CCD Imaging and Photometry with Small Telescopes: Lunar Occultations and Speckle Interferometry

2001 ◽  
Vol 183 ◽  
pp. 309-314
Author(s):  
Jorge Núñez ◽  
Octavi Fors
Keyword(s):  
Data Analysis ◽  
Speckle Interferometry ◽  
Close Binary ◽  
Ccd Cameras ◽  
Ccd Imaging ◽  
Scanning Technique ◽  
Photometric Observations ◽  
Drift Scan ◽  
Fast Drift ◽  
Year 2000

AbstractIn this paper we show how inherent features of typical CCD cameras can be used for fast (in the order of milliseconds) photometric observations (FPO), even with submeter class telescopes. This is based on a modified drift-scanning technique which we show to be advantageous for such kind of observations. In particular, we successfully carried out some lunar occultations and speckle interferometry observations using this technique. During the year 2000, we registered several occultation events. In particular, we present the occultation of SAO79031. The millisecond photometry of the event allows us subsequent data analysis for stellar diameter estimation and close binary detection. We also show an example of the application of the technique to speckle interferometry observations. Finally, we present the main characteristics of our project to build a new remotely controlled observatory near Barcelona.

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