On the Status of the Star Schulte 12 in the Association Cyg OB2

Клочкова, В. Г.; Islentieva, E. S.; Панчук, В. Е.

doi:10.1134/s1063772922110099

Cited by 3 publications

(1 citation statement)

References 26 publications

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“…Cyg OB2-12 appears to be a member of a triple system, with a companion at projected separation ∼100 au, and a second companion at projected separation ∼2000 au (Caballero-Nieves et al 2014;Maryeva et al 2016). Klochkova et al (2022) report radial velocity variations of amplitude ∼8 kms −1 ; if periodic, the period must be 2 yr. Oskinova et al (2017) argue that Cyg OB2-12 is a colliding-wind binary.…”

Section: » mentioning

confidence: 92%

Sensitivity of Polarization to Grain Shape. I. Convex Shapes

Draine

2024

ApJ

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Aligned interstellar grains produce polarized extinction (observed at wavelengths from the far-ultraviolet to the mid-infrared) and polarized thermal emission (observed at far-infrared and submm wavelengths). The grains must be quite nonspherical, but the actual shapes are unknown. The relative efficacy for aligned grains to produce polarization at optical versus infrared wavelengths depends on particle shape. The discrete dipole approximation is used to calculate polarization cross sections for 20 different convex shapes, for wavelengths from 0.1 to 100 μm, and grain sizes a eff from 0.05 to 0.3 μm. Spheroids, cylinders, square prisms, and triaxial ellipsoids are considered. Minimum aspect ratios required by the observed starlight polarization are determined. Some shapes can also be ruled out because they provide too little or too much polarization at far-infrared and submm wavelengths. The ratio of 10 μm polarization to integrated optical polarization is almost independent of grain shape, varying by only ±8% among the viable convex shapes; thus, at least for convex grains, uncertainties in grain shape cannot account for the discrepancy between predicted and observed 10 μm polarization toward Cyg OB2-12.

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Section: » mentioning

confidence: 92%

Sensitivity of Polarization to Grain Shape. I. Convex Shapes

Draine

2024

ApJ

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High Resolution Optical Spectra of the Dormant LBV Star P Cyg

Klochkova,

Panchuk,

Tavolzhanskaya

2023

Astron. Rep.

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HIGH RESOLUTION OPTICAL SPECTRA OF THE DORMANT LBV STAR P Cyg

Klochkova,

Panchuk,

Tavolzhanskaya

2023

Astronomičeskij žurnal

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High resolution optical spectra (R = 60 000) of the dormant LBV star P Cyg were obtained on the BTA telescope in the wavelength range \(\Delta \lambda G7 = 780\) nm. After performing a detailed identification of different types lines (photospheric absorptions, permitted and forbidden emissions, components of lines with profiles of type P Cyg), we studied the variability of their profiles and patterns of radial velocities. The average radial velocity from positions of forbidden emissions ([N II] 5754.64, [Fe II] 5261.62, [Fe II] 7155.14 and [Ni II] 7377.83 Å) is accepted as the system \({{V}_{{{\text{sys}}}}} = - 34 \pm 1.4\) km/s. About a dozen photospheric absorptions of CNO-triad ions and Si III are found, their stable position, \({{V}_{r}}({\text{abs}}) = - 73.8\) km/s, shifted relative to \({{V}_{{{\text{sys}}}}}\) at \( - 40\) km/s, indicates that these absorbtions are formed in the pseudophotosphere region. The high-excitation emissions ([O I] 5577, 6300, 6363 Å, [O III] 4959 and 5007 Å, as well as He II 4686 Å) are absent in the spectra. The radial velocity \({{V}_{r}}({\text{DIBs}}) = - 11.8\) km/s according to the position of numerous DIBs is consistent with the position of the interstellar components of the D-lines Na I and K I forming in the galactic Perseus arm. An excess of color \(E(B - V) = 0.34 \pm {{0.03}^{m}}\) and interstellar absorption \({{A}_{v}}{{ = 1.09}^{m}}\) were determined by measurements of equivalent widths of nine DIBs.

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On the Status of the Star Schulte 12 in the Association Cyg OB2

Cited by 3 publications

References 26 publications

Sensitivity of Polarization to Grain Shape. I. Convex Shapes

Sensitivity of Polarization to Grain Shape. I. Convex Shapes

High Resolution Optical Spectra of the Dormant LBV Star P Cyg

HIGH RESOLUTION OPTICAL SPECTRA OF THE DORMANT LBV STAR P Cyg

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