Experimental and Theoretical Study of Stripe Magnetic Domain Structure Drift in Iron Garnet Crystals

Pamyatnykh, L. A.; Shmatov, G. A.; Pamyatnykh, Sergey E.; Lysov, M. S.; Mekhonoshin, D. S.; Druzhinin, A. V.

doi:10.12693/aphyspola.127.388

Cited by 80 publications

(99 citation statements)

References 6 publications

(6 reference statements)

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“…Here, κ T is defined as ∂ log κ ∂ log T ρ , κ ρ as ∂ log κ ∂ log ρ T , and Γ 3 −1 = ∂ ln T ∂ ln ρ ad . The pulsation properties depend directly on this opacity derivative, in particular, the driving of oscillations (Pamyatnykh 1999). For both OPAL and OPLIB tables, we see a local maximum of the derivative near log T = 5.6, which is not present in OP data.…”

Section: Instability Domainsmentioning

confidence: 75%

“…In the case of OPLIB tables, this border occurs closer to the ZAMS than in the case of OPAL data. Up to about 10 M , the effective low-temperature border is equal to the TAMS, due to strong damping of the high-order g-modes in the radiative core of the evolved stars (Pamyatnykh 1999). For masses higher than 10 M , the low-temperature border reaches the late post main sequence evolution phase, and it is slightly more extended in the case of the OPLIB opacities.…”

Section: Instability Domainsmentioning

confidence: 96%

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Wider pulsation instability regions forβCephei and SPB stars calculated using new Los Alamos opacities

Walczak

Fontes

Colgan

et al. 2015

A&A

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Aims. Our goal is to test the newly developed OPLIB opacity tables from Los Alamos National Laboratory and check their influence on the pulsation properties of B-type stars. Methods. We calculated models using MESA and Dziembowski codes for stellar evolution and linear, nonadiabatic pulsations, respectively. We derived the instability domains of β Cephei and SPB-types for different opacity tables OPLIB, OP, and OPAL. Results. The new OPLIB opacities have the highest Rosseland mean opacity coefficient near the so-called Z-bump. Therefore, the OPLIB instability domains are wider than in the case of OP and OPAL data.

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Section: Instability Domainsmentioning

confidence: 75%

Section: Instability Domainsmentioning

confidence: 96%

Wider pulsation instability regions forβCephei and SPB stars calculated using new Los Alamos opacities

Walczak

Fontes

Colgan

et al. 2015

A&A

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show abstract

“…To excite an oscillation mode, the thermal timescale in the driving zone has to be comparable or longer than the oscillation period (Pamyatnykh 1999). The layers in the stellar envelope, where the local thermal timescale is comparable with the period of a mode under consideration, are the most important layers for the driving and damping of this mode.…”

Section: Discussionmentioning

confidence: 99%

Frequencies and mode identifications of theδScuti star EE Camelopardalis

Breger

Lenz

Pamyatnykh

et al. 2015

A&A

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Aims. EE Cam belongs to a group of slightly evolved main-sequence A stars with intermediate rotational velocities. The pulsation frequencies and their mode identification of this star are of interest in order to compare these with those known for the high-amplitude δ Scuti stars (HADS) and the common fast-rotating low-amplitude δ Scuti pulsators. Methods. The variability of the δ Scuti star EE Cam was observed photometrically for more than 300 nights from 2006 to 2010. Results. Forty pulsation frequencies are identified, ranging from 3.4 to 13.3 cd −1 (40 to 154 μHz). The frequency distribution of the residuals suggests the presence of a large number of additional small-amplitude modes in the same frequency range. We compare the observed phase differences and amplitude ratios with those predicted by pulsation models. The dominant mode at 4.93 cd −1 is found to be a radial mode, while the mode at 5.21 cd −1 is identified as a nonradial = 1 mode. Furthermore, when we compare the frequency range of the detected modes with detailed stellar models of pulsational instability, the radial mode is found to be the fundamental mode. Conclusions. We have studied and presented the pulsation behavior of EE Cam. It demonstrates that a moderately rotating star can exhibit the behavior of the two groups of δ Scuti stars: the identification of the dominant mode as the radial fundamental is similar to that found in the slowly rotating HADS, and the presence of a very large number of low-amplitude nonradial modes resembles the property of the fast rotating low-amplitude δ Scuti stars.

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“…According to asteroseismology, the terminal-age MS is a hard boundary for the instability strip of SPB stars owing to the very strong damping of high-order gravity modes in the interiors of post-MS stars (Pamyatnykh 1999). Under this premise, 18 Peg is expected to be a MS star given its SPB nature.…”

Section: Potential Benchmark Star For Upper Main Sequence Stellar Evomentioning

confidence: 99%

The slowly pulsating B-star 18 Pegasi: A testbed for upper main sequence stellar evolution

Irrgang¹,

Desphande²,

Moehler³

et al. 2016

A&A

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The predicted width of the upper main sequence in stellar evolution models depends on the empirical calibration of the convective overshooting parameter. Despite decades of discussions, its precise value is still unknown and further observational constraints are required to gauge it. Based on a photometric and preliminary asteroseismic analysis, we show that the mid B-type giant 18 Peg is one of the most evolved members of the rare class of slowly pulsating B-stars and, thus, bears tremendous potential to derive a tight lower limit for the width of the upper main sequence. In addition, 18 Peg turns out to be part of a single-lined spectroscopic binary system with an eccentric orbit that is greater than 6 years. Further spectroscopic and photometric monitoring and a sophisticated asteroseismic investigation are required to exploit the full potential of this star as a benchmark object for stellar evolution theory.

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Experimental and Theoretical Study of Stripe Magnetic Domain Structure Drift in Iron Garnet Crystals

Cited by 80 publications

References 6 publications

Wider pulsation instability regions forβCephei and SPB stars calculated using new Los Alamos opacities

Wider pulsation instability regions forβCephei and SPB stars calculated using new Los Alamos opacities

Frequencies and mode identifications of theδScuti star EE Camelopardalis

The slowly pulsating B-star 18 Pegasi: A testbed for upper main sequence stellar evolution

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