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We determine rotation periods of a sample of 48 late F-type to mid-M dwarf stars using time-series high-resolution spectroscopy of the Ca II H&K and H-alpha chromospheric activity indicators. We find good agreement between the rotation…

Earth and Planetary Astrophysics · Physics 2015-08-06 A. Suárez Mascareño , R. Rebolo , J. I. González Hernández , M. Esposito

Sgr A* is variable at radio and submillimeter wavelengths on hourly time scales showing time delays between the peaks of flare emission as well as linearly polarized emission at millimeter and sub-mm wavelengths. To determine the…

Astrophysics · Physics 2009-11-13 F. Yusef-Zadeh , M. Wardle , W. D. Cotton , C. O. Heinke , D. A. Roberts

The reported nightly mean value of the circular polarization of optical emission observed from the close binary system AE Aqr is 0.06% (+-) 0.01%. We discuss a possibility that the observed polarized radiation is emitted mainly by the white…

Astrophysics · Physics 2009-11-07 N. R. Ikhsanov , S. Jordan , N. G. Beskrovnaya

New polarimetric observations of the Crab pulsar at frequencies between 1.4 and 8.4 GHz are presented. Additional pulse components discovered in earlier observations (Moffett & Hankins 1996, astro-ph/9604163) are found to have high levels…

Astrophysics · Physics 2009-10-31 D. A. Moffett , T. H. Hankins

Angular power spectra computed from Planck HFI 353 GHz intensity and polarization maps produce a TB correlation that can be approximated by a power law. Whether the observed TB correlation is an induced systematic feature or a physical…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-17 J. L. Weiland , G. E. Addison , C. L. Bennett , M. Halpern , G. Hinshaw

We calculate the polarization of radiation from thick accretion disks with vertically averaged global magnetic field. The polarization arises as a result of the radiation scattering by free electrons in magnetized plasma of a disk. We…

Astrophysics · Physics 2007-05-23 Yu. N. Gnedin , N. A. Silant'ev , P. S. Shternin

We have analysed the optical polarimetric properties of nearby intermediate-late type MS stars and examined in some detail the pecularities displayed by those known to have planets. We find that: i) the polarization degree is not strictly…

Astrophysics · Physics 2009-11-07 F. Tamburini , A. Bianchini , S. Ortolani

Using the first station of the Long Wavelength Array (LWA1), we examine polarized pulsar emission between 25 and 88 MHz. Polarized light from pulsars undergoes Faraday rotation as it passes through the magnetized interstellar medium.…

High Energy Astrophysical Phenomena · Physics 2020-07-01 V. Dike , G. B. Taylor , J. Dowell , K. Stovall

M dwarfs are active stars that exhibit variability in chromospheric emission and photometry at short and long timescales, including long cycles that are related to dynamo processes. This activity also impacts the search for exoplanets…

Solar and Stellar Astrophysics · Physics 2023-07-19 L. Mignon , N. Meunier , X. Delfosse , X. Bonfils , N. C. Santos , T. Forveille , G. Gaisné , N. Astudillo-Defru , C. Lovis , S. Udry

Light scattering by atmospheric dust particles is responsible for the polarization observed in some L dwarfs. Whether this polarization arises from an inhomogeneous distribution of dust across the disk or an oblate shape induced by rotation…

Solar and Stellar Astrophysics · Physics 2015-05-19 Sujan Sengupta , Mark S. Marley

The characterization of the polarimetric properties of the planet Earth is important for the interpretation of expected observations and the planning of future instruments. We present a multi-wavelengths and multi-phase set of benchmark…

Earth and Planetary Astrophysics · Physics 2015-06-16 Andreas Bazzon , Hans Martin Schmid , Daniel Gisler

We estimate the average fractional polarisation at 143, 217 and 353 GHz of a sample of 4697 extragalactic dusty sources by applying stacking technique. The sample is selected from the second version of the Planck Catalogue of Compact…

Astrophysics of Galaxies · Physics 2023-04-05 L. Bonavera , J. Gonzalez-Nuevo , B. De Marco , F. Argüeso , L. Toffolatti

The sample of white dwarfs included in the local 20 pc volume documents, fairly accurately, the total production of white dwarfs over roughly 10 Gyr of stellar evolution in this part of the Milky Way Galaxy. In this sample, we have been…

Solar and Stellar Astrophysics · Physics 2020-11-18 S. Bagnulo , J. D. Landstreet

Isolated Neutron Stars are known to be endowed with extreme magnetic fields, whose maximum intensity ranges from 10^12 to 10^15 G, which permeates their magnetospheres. Their surrounding environment is also strongly magnetised, especially…

High Energy Astrophysical Phenomena · Physics 2018-02-01 R. P. Mignani

We present a study of the variation timescales of the chromospheric activity indicator H$\alpha$ on a sample of 13 fully-convective, active mid-to-late M stars with masses between 0.1--0.3 solar masses. Our goal was to determine the…

Solar and Stellar Astrophysics · Physics 2022-04-13 Amber A. Medina , David Charbonneau , Jennifer G. Winters , Jonathan Irwin , Jessica Mink

We investigate the activity induced signals related to rotation in late type stars (FGKM). We analyse the Ca II H&K, the H alpha and the radial velocity time-series of 55 stars using the spectra from the HARPS public database and the…

Earth and Planetary Astrophysics · Physics 2017-05-31 A. Suárez Mascareño , R. Rebolo , J. I. González Hernández , M. Esposito

We present polarization data for 32 mainly southern pulsars at 8.4 GHz. The observations show that the polarization fraction is low in most pulsars at this frequency except for the young, energetic pulsars which continue to show…

Astrophysics · Physics 2016-08-16 Simon Johnston , Aris Karastergiou , Kyle Willett

New observations of 9 of the brightest northern O stars have been made with the Breger polarimeter on the 0.9~m telescope at McDonald Observatory and the AnyPol polarimeter on the 0.4~m telescope at Limber Observatory, using the…

Astrophysics · Physics 2009-10-31 David McDavid

We report observations of the linear polarization of a sample of 49 nearby bright stars measured to sensitivities of between ~1 and 4 x 10^-6. The majority of stars in the sample show measurable polarization, but most polarizations are…

Solar and Stellar Astrophysics · Physics 2015-05-18 Jeremy Bailey , P. W. Lucas , J. H. Hough

Polarization from active galactic nuclei is interpreted as a signpost of the role of magnetic fields in the launch and collimation of their relativistic radio jets. Here, we report the detection of a clear polarization signal from ALMA…

Astrophysics of Galaxies · Physics 2018-12-26 I. Marti-Vidal , S. Muller