Toward the global magnetic field of the planet‐hosting red giant eps Tau

2021 ◽  
Author(s):  
Sergei Ivanovich Plachinda ◽  
Varvara Vladimirovna Butkovskaya ◽  
Nikolai Fedorovich Pankov
Keyword(s):  
Magnetic Field ◽  
Global Magnetic Field ◽  
Red Giant

scholarly journals On the origin of variable structures in the winds of hot luminous stars

2013 ◽  
Vol 440 (1) ◽  
pp. 2-9 ◽  
Author(s):  
Yannick J. L. Michaux ◽  
Anthony F. J. Moffat ◽  
André-Nicolas Chené ◽  
Nicole St-Louis
Keyword(s):  
Magnetic Field ◽  
Empirical Evidence ◽  
Temporal Variability ◽  
Large Scale ◽  
Small Scale ◽  
Ionization Zone ◽  
Corotating Interaction Regions ◽  
Wind Variability ◽  
Global Magnetic Field ◽  
Interaction Regions

Abstract Examination of the temporal variability properties of several strong optical recombination lines in a large sample of Galactic Wolf–Rayet (WR) stars reveals possible trends, especially in the more homogeneous WC than the diverse WN subtypes, of increasing wind variability with cooler subtypes. This could imply that a serious contender for the driver of the variations is stochastic, magnetic subsurface convection associated with the 170 kK partial-ionization zone of iron, which should occupy a deeper and larger zone of greater mass in cooler WR subtypes. This empirical evidence suggests that the heretofore proposed ubiquitous driver of wind variability, radiative instabilities, may not be the only mechanism playing a role in the stochastic multiple small-scaled structures seen in the winds of hot luminous stars. In addition to small-scale stochastic behaviour, subsurface convection guided by a global magnetic field with localized emerging loops may also be at the origin of the large-scale corotating interaction regions as seen frequently in O stars and occasionally in the winds of their descendant WR stars.

scholarly journals A multi-wavelength analysis of the WASP-12 planetary system

2010 ◽  
Vol 6 (S276) ◽  
pp. 163-166 ◽  
Author(s):  
Luca Fossati ◽  
Carole A. Haswell ◽  
Cynthia S. Froning
Keyword(s):  
Magnetic Field ◽  
Atmospheric Pollution ◽  
Planetary System ◽  
Light Curves ◽  
Absorption Lines ◽  
Transiting Planets ◽  
Multi Wavelength ◽  
Global Magnetic Field ◽  
Solar Type ◽  
Solar Type Star

AbstractWASP-12 is a 2 Gyr old solar type star, hosting WASP-12b, one of the most irradiated transiting planets currently known. We observed WASP-12 in the UV with the Cosmic Origins Spectrograph (COS) on HST. The light curves we obtained in the three covered UV wavelength ranges, all of which contain many photospheric absorption lines, imply effective radii of 2.69±0.24 RJ, 2.18±0.18 RJ, and 2.66±0.22 RJ, suggesting that the planet is surrounded by an absorbing cloud which overfills the Roche lobe. We clearly detected enhanced transit depths at the wavelengths of the MgII h&k resonance lines. Spectropolarimetric analysis of the host star was also performed. We found no global magnetic field, but there were hints of atmospheric pollution, which might be connected to the very unusual activity of the host star.

scholarly journals Effect of a strong magnetic field on gravity-mode period spacings in red giant stars

2020 ◽  
Vol 496 (3) ◽  
pp. 3829-3840
Author(s):  
Shyeh Tjing Loi
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Strong Field ◽  
Average Density ◽  
Stellar Structure ◽  
Frequency Interval ◽  
Giant Stars ◽  
Red Giant Stars ◽  
Red Giant ◽  
Gravity Mode

ABSTRACT When a star evolves into a red giant, the enhanced coupling between core-based gravity modes and envelope-based pressure modes forms mixed modes, allowing its deep interior to be probed by asteroseismology. The ability to obtain information about stellar interiors is important for constraining theories of stellar structure and evolution, for which the origin of various discrepancies between prediction and observation is still under debate. Ongoing speculation surrounds the possibility that some red giant stars may harbour strong (dynamically significant) magnetic fields in their cores, but interpretation of the observational data remains controversial. In part, this is tied to shortfalls in our understanding of the effects of strong fields on the seismic properties of gravity modes, which lies beyond the regime of standard perturbative methods. Here, we seek to investigate the effect of a strong magnetic field on the asymptotic period spacings of gravity modes. We use a Hamiltonian ray approach to measure the volume of phase space occupied by mode-forming rays, this being roughly proportional to the average density of modes (number of modes per unit frequency interval). A strong field appears to systematically increase this by about 10 per cent, which predicts a ∼10 per cent smaller period spacing. Evidence of near integrability in the ray dynamics hints that the gravity-mode spectrum may still exhibit pseudo-regularities under a strong field.

A Picture of Solar Minimum and the Onset of Solar Cycle 23. I. Global Magnetic Field Evolution

2000 ◽  
Vol 529 (2) ◽  
pp. 1101-1114 ◽  
Author(s):  
Giuliana de Toma ◽  
Oran R. White ◽  
Karen L. Harvey
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Solar Minimum ◽  
Field Evolution ◽  
Solar Cycle 23 ◽  
Global Magnetic Field

Introductory remarks

1994 ◽  
Vol 349 (1690) ◽  
pp. 169-170
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Royal Society ◽  
Lunar Regolith ◽  
The Moon ◽  
Global Magnetic Field ◽  
The Subject ◽  
Planetary Missions ◽  
Speculative Hypothesis ◽  
First Time

This year marks not only the twenty-fifth anniversary of the first manned landing on the Moon ( Apollo 11 ) but also the thirty-fifth anniversary of the first planetary missions. The latter was the Soviet Luna 1 and 2 carrying magnetometers to test whether the Moon possessed a global magnetic field. Luna 1 passed the Moon but Luna 2 crash landed, both showed that the Moon had no magnetic field as large as 50 or 100 y (1 y = 10 -5 G = 10 -9 T). Such an experiment had been proposed by S. Chapman ( Nature 160, 395 (1947)) to test a speculative hypothesis concerning magnetic fields of cosmic bodies by P. M. S. Blackett ( Nature 159, 658 (1947)). Chapman’s suggestion was greeted by general amusement: 12 years later it was accomplished. Also two years after the launch of Sputnik 1 in 1957, Luna 3 was launched and for the first time viewed the far side of the Moon on 9 October, 1959. Laboratories from many countries were invited by NASA to take part in the analysis of rocks returned from the Apollo missions and later from the Soviet automated return of cores from the lunar regolith. British laboratories were very active in this work, and a review of the results of the new understanding of the Moon as a result of space missions formed the subject of a Royal Society Discussion Meeting in 1975 (published in Phil. Trans. R. Soc. Lond . A 285). British laboratories received samples from the automated Soviet missions that took cores from the regolith and returned them to Earth. Work on Luna 16 and 20 samples were published in Phil. Trans. R. Soc. Lond . A 284 131-177 (1977) and on Luna 24 in Phil. Trans. R. Soc. Lond . A 297 1-50 (1979).

scholarly journals A Comparison of Global Magnetic Field Skeletons and Active-Region Upflows

Solar Physics ◽  
2015 ◽  
Vol 291 (1) ◽  
pp. 117-142 ◽  
Author(s):  
S. J. Edwards ◽  
C. E. Parnell ◽  
L. K. Harra ◽  
J. L. Culhane ◽  
D. H. Brooks
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Global Magnetic Field

scholarly journals Coronal global EIT waves as tools for multiple diagnostics

2007 ◽  
Vol 3 (S247) ◽  
pp. 243-250
Author(s):  
I. Ballai ◽  
M. Douglas
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Solar Disk ◽  
Coronal Loop ◽  
Large Scale ◽  
Theoretical Models ◽  
Coronal Loops ◽  
Quiet Sun ◽  
Propagating Waves ◽  
Global Magnetic Field

AbstractObservations in EUV lines of the solar corona revealed large scale propagating waves generated by eruptive events able to travel across the solar disk for large distances. In the low corona, CMEs are known to generate, e.g. EIT waves which can be used to sample the coronal local and global magnetic field. This contribution presents theoretical models for finding values of magnetic field in the quiet Sun and coronal loops based on the interaction of global waves and local coronal loops as well as results on the generation and propagation of EIT waves. The physical connection between local and global solar coronal events (e.g. flares, EIT waves and coronal loop oscillations) will also be explored.

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