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Global magnetic fields of early-type stars are commonly characterised by the mean longitudinal magnetic field $\langle B_{\rm z} \rangle$ and the mean field modulus $\langle B \rangle$, derived from the circular polarisation and intensity…

Solar and Stellar Astrophysics · Physics 2024-04-29 O. Kochukhov

Numerical simulations of realistic non-vacuum magnetospheres of isolated neutron stars have shown that pulsar spin-down luminosities depend weakly on the magnetic obliquity. This result provides the opportunity to estimate the surface…

High Energy Astrophysical Phenomena · Physics 2017-02-21 Anton Biryukov , Artyom Astashenok , Gregory Beskin

Electric currents play an important role in the energy balance of the plasma in the solar atmosphere. They are also indicative of non-potential magnetic fields and magnetic reconnection. Unfortunately, the direct measuring of electric…

Solar and Stellar Astrophysics · Physics 2023-01-25 J. M. Borrero , A. Pastor Yabar

Neutron stars radiate in a broad band spectrum from radio wavelengths up to very high energies. They have been sorted into several classes depending on their respective place in the $P-\dot{P}$ diagram and depending on spectral/temporal…

High Energy Astrophysical Phenomena · Physics 2019-03-20 Jérôme Pétri

Plaskett's "star" appears to be one of a small number of short-period binary systems known to contain a hot, massive, magnetic star. Building on the 2013 discovery investigation, we combine an extensive spectropolarimetric (Stokes $V$)…

Solar and Stellar Astrophysics · Physics 2022-04-06 J. H. Grunhut , G. A. Wade , C. P. Folsom , C. Neiner , O. Kochukhov , E. Alecian , M. Shultz , V. Petit , the MiMeS , BinaMIcS collaborations

Stokes inversion codes are crucial in returning properties of the solar atmosphere, such as temperature and magnetic field strength. However, the success of such algorithms to return reliable values can be hindered by the presence of…

Solar and Stellar Astrophysics · Physics 2021-01-20 P. H. Keys , O. Steiner , G. Vigeesh

The Mg II k resonance line is commonly used for diagnosing the solar chromosphere. We theoretically investigated its intensity and polarization in solar prominences, taking 3D radiative transfer and Hanle and Zeeman effects into account. We…

Solar and Stellar Astrophysics · Physics 2024-09-25 Jiří Štěpán , Tanausú del Pino Alemán , Javier Trujillo Bueno

The MHD virial theorem may be used to estimate the magnetic energy of active regions based on vector magnetic fields measured at the photosphere or chromosphere. However, the virial estimate depends on the measured vector magnetic field…

Astrophysics · Physics 2009-11-13 M. S. Wheatland , T. R. Metcalf

The standard methods of the magnetic field measurement, based on an analysis of the relation between the Stokes $V$-parameter and the first derivative of the total line profile intensity, were modified by applying a linear integral operator…

Solar and Stellar Astrophysics · Physics 2015-06-15 A. F. Kholtygin

The big majority of the reported measurements of the stellar magnetic fields that have analysed spectropolarimetric data have employed the least-square-deconvolution method (LSD) and the first-order moment approach. We present a series of…

Solar and Stellar Astrophysics · Physics 2020-04-01 J. C. Ramírez Vélez

Context. A lot of effort has been put into the detection and determination of stellar magnetic fields using the spectral signal obtained from the combination of hundreds or thousands of individual lines, an approach known as multi-line…

Solar and Stellar Astrophysics · Physics 2016-12-07 J. C. Ramírez Vélez , M. J. Stift , S. G. Navarro , J. P. Córdova , L. Sabin , A. Ruelas-Mayorga

Optical spectropolarimeters can be used to produce maps of the surface magnetic fields of stars and hence to determine how stellar magnetic fields vary with stellar mass, rotation rate, and evolutionary stage. In particular, we now can map…

Solar and Stellar Astrophysics · Physics 2015-05-20 S. G. Gregory

Stellar spectra contain a large amount of information about the conditions in stellar atmospheres. However, extracting this information is challenging and demands comprehensive numerical modelling. Here, we present stellar spectra…

Solar and Stellar Astrophysics · Physics 2023-03-07 N. Kostogryz , A. I Shapiro , V. Witzke , D. Grant , H. R. Wakeford , K. B. Stevenson , S. K. Solanki , L. Gizon

Fully analytic expressions, for the electric and magnetic fields of an ultrashort and tightly focused laser pulse of the radially polarized category, are presented to lowest order of approximation. The fields are derived from scalar and…

Optics · Physics 2017-10-11 Yousef I. Salamin , Jian-Xing Li

Magnetars are believed to host the strongest magnetic fields in the present universe ($B\gtrsim10^{14}$ G) and the study of their persistent emission in the X-ray band offers an unprecendented opportunity to gain insight into physical…

High Energy Astrophysical Phenomena · Physics 2020-03-03 Roberto Taverna , Roberto Turolla , Valery Suleimanov , Alexander Y. Potekhin , Silvia Zane

Inversion techniques applied to the radiative transfer equation for polarized light are capable of inferring the physical parameters in the solar atmosphere (temperature $T$, magnetic field ${\bf B}$, and line-of-sight velocity $v_{\rm…

Solar and Stellar Astrophysics · Physics 2021-04-07 J. M. Borrero , A. Pastor Yabar , B. Ruiz Cobo

We present a relativistic model of pulsar radio emission by plasma accelerated along the rotating magnetic field lines projected on to a 2D plane perpendicular to the rotation axis. We have derived the expression for the trajectory of a…

Astrophysics · Physics 2007-05-23 R. M. C. Thomas , R. T. Gangadhara

The high-precision measurements of exoplanet transit light curves that are now available contain information about the planet properties, their orbital parameters, and stellar limb darkening (LD). Recent 3D magneto-hydrodynamical (MHD)…

Solar and Stellar Astrophysics · Physics 2024-10-11 Kuldeep Verma , Pierre F. L. Maxted , Anjali Singh , H. -G. Ludwig , Yashwardhan Sable

The Stokes parameters of the pulsed synchrotron radiation produced in the striped pulsar wind model are computed and compared with optical observations of the Crab pulsar. We assume the main contribution to the wind emissivity comes from a…

Astrophysics · Physics 2009-11-11 J. Petri , J. Kirk

Double-resonance optically pumped magnetometers are an attractive instrument for unshielded magnetic field measurements due to their wide dynamic range and high sensitivity. Use of linearly polarised pump light creates alignment in the…

Atomic Physics · Physics 2018-09-26 Stuart J. Ingleby , Carolyn O'Dwyer , Paul F. Griffin , Aidan S. Arnold , Erling Riis