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We present magnetic flux measurements in seven rapidly rotating M dwarfs. Our sample stars have X-ray and H-alpha emission indicative of saturated emission, i.e., emission at a high level independent of rotation rate. Our measurements are…

Astrophysics · Physics 2011-02-11 A. Reiners , G. Basri , M. Browning

The nature of non-variable high-excitation emission lines detected in the optical spectra of normal late-B type and chemically peculiar HgMn and PGa stars is still poorly understood. To better understand the origin of the weak emission…

Astrophysics · Physics 2009-11-13 S. Hubrig , J. F. Gonzalez

We present our analysis aimed at inferring average magnetic fields in slowly-rotating solar-like stars. Using the spectral line inversion code SPINOR, we perform high-accuracy line profile fitting and investigate whether Zeeman broadening…

Solar and Stellar Astrophysics · Physics 2010-12-15 Richard I. Anderson , Ansgar Reiners , Sami K. Solanki

The contribution of the quiet Sun to solar irradiance variability, due either to changes of the solar effective temperature or to the presence of unresolved magnetic field, is still poorly understood. In this study we investigate spectral…

Solar and Stellar Astrophysics · Physics 2015-06-12 Serena Criscuoli , Ilaria Ermolli , Han Uitenbroek , Fabrizio Giorgi

High-dispersion, archival spectra of magnetic Ap stars with resolved Zeeman components in Stokes I are used to derive a simple relation that can be utilised to estimate the mean surface field strengths of stars with v sin i > 10 km/s. For…

Solar and Stellar Astrophysics · Physics 2014-09-05 J. D. Bailey

We aim to characterise the small-scale magnetic fields for a sample of 16 Sun-like stars and investigate the capabilities of the newly upgraded near-infrared (NIR) instrument CRIRES$^+$ at the VLT in the context of small-scale magnetic…

We performed a highly sensitive search for magnetic fields on a large set of HgMn stars. With the aid of a new polarimeter attached to the HARPS spectrometer at the ESO 3.6m-telescope, we obtained high-quality circular polarization spectra…

Context. Recent high angular resolution polarimetric continuum observations of circumstellar disks provide new insights into their magnetic field. However, direct constraints are limited to the plane of sky component of the magnetic field.…

Solar and Stellar Astrophysics · Physics 2017-11-22 R. Brauer , S. Wolf , M. Flock

The main-sequence mercury-manganese (HgMn) stars are known to exhibit large overabundances of exotic elements and, similar to magnetic Ap/Bp stars, are spectrum variables, implying the presence of an inhomogeneous element distribution over…

Solar and Stellar Astrophysics · Physics 2020-04-29 S. Hubrig , S. P. Jarvinen , H. Korhonen , I. Ilyin , M. Schöller , E. Niemczura , S. D. Chojnowski

Magnetic fields play a fundamental role for interior and atmospheric properties of M dwarfs and greatly influence terrestrial planets orbiting in the habitable zones of these low-mass stars. Determination of the strength and topology of…

Solar and Stellar Astrophysics · Physics 2020-12-23 Oleg Kochukhov

(Edited for length) The Zeeman effect is the only observational technique available to measure directly the strength of magnetic fields in regions of star formation. We review the physics of the Zeeman effect and its practical use in both…

Astrophysics of Galaxies · Physics 2019-11-15 Richard M. Crutcher , Athol J. Kemball

The infrared Mg I lines near 12 microns are a pair of emission lines which are magnetically sensitive and have been used to measure solar magnetic fields. Here we calculate the response of the Mg I 12.32 $\mu$m line during a flare and find…

Solar and Stellar Astrophysics · Physics 2020-08-04 Jie Hong , Xianyong Bai , Ying Li , M. D. Ding , Yuanyong Deng

Emission-lines of magnesium at 12 microns have been observed in the spectrum of Procyon. We reproduce the observed, disk-averaged line flux from Procyon (as well as the observed intensity profiles from the Sun) by calculating the line…

Astrophysics · Physics 2009-11-10 Nils Ryde , Andreas Korn , Matthew Richter , Felix Ryde

Average magnetic field measurements are presented for 62 M-dwarf members of the Pleiades open cluster, derived from Zeeman-enhanced Fe I lines in the H-band. An MCMC methodology was employed to model magnetic filling factors using SDSS-IV…

We investigate the possibility of measuring magnetic field strength in G-band bright points through the analysis of Zeeman polarization in molecular CH lines. To this end we solve the equations of polarized radiative transfer in the G band…

Astrophysics · Physics 2009-11-10 H. Uitenbroek , E. Miller-Ricci , A. Asensio Ramos , J. Trujillo Bueno

We have obtained accurate circular spectropolarimetric observations for a sample of Vega-like and Herbig Ae/Be stars with FORS1 at the VLT in an attempt to detect their magnetic fields. No magnetic field could be diagnosed in any Vega-like…

Astrophysics · Physics 2016-08-30 S. Hubrig , R. V. Yudin , M. Schoeller , M. A. Pogodin

Magnetic white dwarfs with field strengths below 10 MG are easy to recognise since the Zeeman splitting of spectral lines appears proportional to the magnetic field strength. For fields $\geq 100$ MG, however, transition wavelengths become…

Solar and Stellar Astrophysics · Physics 2023-01-25 Mark A. Hollands , Stella Stopkowicz , Marios-Petros Kitsaras , Florian Hampe , Simon Blaschke , J. J. Hermes

Stars which are rapidly rotating are expected to show high levels of activity according to the activity-rotation relation. However, previous TESS studies have found Ultra Fast Rotating (UFR) M dwarfs with periods less than one day…

Solar and Stellar Astrophysics · Physics 2022-03-02 Lauren Doyle , Stefano Bagnulo , Gavin Ramsay , Gerry Doyle , Pasi Hakala

We present an analysis of infrared (IR) echelle spectra of five stars in the TW Hydrae Association (TWA). We model the Zeeman broadening in four magnetic-sensitive \ion{Ti}{1} lines near $2.2 \mu$m and measure the value of the photospheric…

Astrophysics · Physics 2009-11-13 Hao Yang , Christopher M. Johns-Krull , Jeff A. Valenti

For several decades we have been cognizant of the presence of magnetic fields in early-type stars, but our understanding of their magnetic properties has recently (over the last decade) expanded due to the new generation of high-resolution…

Solar and Stellar Astrophysics · Physics 2015-06-16 Jason H. Grunhut , Coralie Neiner