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The Zeeman effect is of limited utility for probing the magnetism of the quiet solar chromosphere. The Hanle effect in some spectral lines is sensitive to such magnetism, but the interpretation of the scattering polarization signals…

Solar and Stellar Astrophysics · Physics 2021-04-21 Jan Jurcak , Jiri Stepan , Javier Trujillo Bueno

Magnetic fields of cool stars can be directly investigated through the study of the Zeeman effect on photospheric spectral lines using several approaches. With spectroscopic measurement in unpolarised light, the total magnetic flux averaged…

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

Approximately 7% of massive stars host stable surface magnetic fields that are strong enough to alter stellar evolution through their effect on the stellar wind. It is therefore crucial to characterize the strength and structure of these…

Solar and Stellar Astrophysics · Physics 2021-07-20 C. Erba , V. Petit , K. Gayley , R. Ignace , A. ud-Doula , G. A. Wade

Magnetic fields significantly influence the evolution of protoplanetary disks and the formation of planets, following the predictions of numerous magnetohydrodynamic (MHD) simulations. However, these predictions are yet observationally…

Earth and Planetary Astrophysics · Physics 2016-11-09 Gesa H. -M. Bertrang , Mario Flock , Sebastian Wolf

A number of prominent spectral lines in the spectra of magnetic A and B main sequence stars are produced by closely spaced doublets or triplets. Depending on the strength and orientation of magnetic field, the PPB magnetic splitting can…

Solar and Stellar Astrophysics · Physics 2015-06-01 V. Khalack , J. Landstreet

Numerical simulations of magneto-convection and analysis of solar magnetogram data provide empirical probability density functions (PDFs) for the line-of-sight component of the magnetic field. In this paper, we theoretically explore effects…

Solar and Stellar Astrophysics · Physics 2010-03-24 M. Sampoorna

Measurements of interplanetary magnetic fields have long relied on spacecraft measurements, which provide only in-situ sampling and therefore cannot capture the global magnetic structure. Faraday rotation of radio signals extends in-situ…

Space Physics · Physics 2026-05-28 Chuanpeng Hou , Huirong Yan , Siqi Zhao

The only way to obtain reliable empirical information on the intensity and topology of the weak magnetic fields of the quiet solar chromosphere is via the measurement and rigorous physical interpretation of polarization signals in…

Astrophysics · Physics 2011-04-12 J. Trujillo Bueno , R. Manso Sainz

In this paper we study the feasibility of inferring the magnetic field from polarized multi-line spectra using two methods: The pseudo line approach and The PCA-ZDI approach. We use multi-line techniques, meaning that all the lines of a…

Solar and Stellar Astrophysics · Physics 2015-05-14 J. C. Ramirez Velez , M. Semel , M. Stift , M. J. Martinez Gonzalez , P. Petit , N. Dunstone

Strong, globally-organized magnetic fields are found for a small fraction of O, B, and A stars. At the same time, many theoretical and indirect observational studies suggested ubiquitous presence of weak localized magnetic fields at the…

Solar and Stellar Astrophysics · Physics 2015-06-15 O. Kochukhov , N. Sudnik

Multiline techniques assuming similar line profiles have become a standard tool in stellar astronomy for increasing the signal-to-noise ratio (SNR) of spectropolarimetric measurements. However, due to the widely-used weak field…

Solar and Stellar Astrophysics · Physics 2010-03-29 C. Sennhauser , S. V. Berdyugina

We report recent ESPaDOnS and HARPSpol spectropolarimetric observations from our ongoing magnetic survey of the brightest twenty-five classical Cepheids. Stokes $V$ magnetic signatures are detected in eight of fifteen targets observed to…

Solar and Stellar Astrophysics · Physics 2024-11-20 James A. Barron , Gregg A. Wade , Colin P. Folsom , Oleg Kochukhov

Magnetic fields are expected to play an important role in accretion processes for circumstellar disks. Measuring the magnetic field morphology is difficult, especially since polarimetric (sub)millimeter continuum observations may not trace…

Solar and Stellar Astrophysics · Physics 2020-09-30 Ian W. Stephens , Manuel Fernandez-Lopez , Zhi-Yun Li , Leslie W. Looney , Richard Teague

We have developed the method that allows us to estimate the magnetic field strength at the horizon of a supermassive black hole (SMBH) through the observed polarization of optical emission of the accreting disk surrounding SMBH. The known…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 N. A. Silant'ev , M. Yu. Piotrovich , Yu. N. Gnedin , T. M. Natsvlishvili

We report the systematic detection of magnetic fields in massive (M > 5 M$_\odot$) late-type supergiants, using spectropolarimetric observations obtained with ESPaDOnS at the Canada-France-Hawaii Telescope. Our observations reveal…

Solar and Stellar Astrophysics · Physics 2015-05-19 Jason H. Grunhut , Gregg A. Wade , David A. Hanes , Evelyne Alecian

The weak-field approximation is one of the simplest models that allows us to relate the observed polarization induced by the Zeeman effect with the magnetic field vector present on the plasma of interest. It is usually applied for…

Solar and Stellar Astrophysics · Physics 2015-05-27 A. Asensio Ramos

We conduct simulations of the inner regions of protoplanetary disks (PPDs) to investigate the effects of protostellar magnetic fields on their long-term evolution. We use an inner boundary model that incorporates the influence of a stellar…

Solar and Stellar Astrophysics · Physics 2021-12-01 D. Steiner , L. Gehrig , B. W. Ratschiner , F. Ragossnig , E. I. Vorobyov , M. Güdel , E. A. Dorfi

The solar photospheric magnetic field is highly structured owing to its interaction with the convective flows. Its local structure has a strong influence on the profiles of spectral lines not only by virtue of the Zeeman effect, but also…

Solar and Stellar Astrophysics · Physics 2014-08-13 Benjamin Beeck , Manfred Schüssler , Ansgar Reiners

Molecular line observations that could resolve protoplanetary disks of ~100 AU both spatially and kinematically would be a useful tool to unambiguously identify these disks and to determine their kinematical and physical characteristics. In…

Astrophysics · Physics 2009-10-31 Jose F. Gomez , Paola D'Alessio