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Two coherent radio emission mechanisms operate in stellar coronae: plasma emission and cyclotron emission. They directly probe the electron density and magnetic field strength respectively. Most stellar radio detections have been made at…

太阳与恒星天体物理 · 物理学 2020-11-11 H. K. Vedantham

In order to investigate the relationship between the local environment and the properties of natal star clusters, we obtained radio observations of 25 star-forming galaxies within 20 Mpc using the Very Large Array (VLA) and the Australia…

星系天体物理 · 物理学 2011-03-11 Alan Aversa , Kelsey Johnson , Crystal Brogan , W. Goss , D. J. Pisano

We present the results of a series of radio, optical, X-ray and gamma-ray observations of the BL Lac object S50716+714 carried out between April 2007 and January 2011. The multi-frequency observations were obtained using several ground and…

Recent radio observations support a picture for star formation where there is accretion of matter onto a central protostar with the ejection of molecular outflows that can affect the surrounding medium. The impact of a supersonic outflow on…

天体物理学 · 物理学 2011-03-10 A. T. Araudo , G. E. Romero , V. Bosch-Ramon , J. M. Paredes

We present VLBA 1.6, 5, 8.4 and 15 GHz observations of a new sample of weak, young, compact candidates for radio faders selected from the VLA FIRST survey. We claim that some, or even the majority of young sources, may be short-lived…

天体物理学 · 物理学 2007-05-23 M. Kunert-Bajraszewska , A. Marecki , R. E. Spencer

Fast radio bursts (FRBs) are extra-galactic sources with unknown physical mechanisms. They emit millisecond-duration radio pulses with isotropic equivalent energy of $10^{36}\sim10^{41}$ ergs. This corresponds to a brightness temperature of…

We report on full-polarization radio observations of the Perseus cluster (Abell 426) using the Westerbork Synthesis Radio Telescope (WSRT) at wavelengths from 81-95 cm. We have employed a novel technique, Rotation Measure synthesis…

天体物理学 · 物理学 2009-11-13 A. G. de Bruyn , M. A. Brentjens

Variability in Young Stellar Objects (YSOs) is one of their primary characteristics. Long-term, multi-filter, high-cadence monitoring of large YSO samples is the key to understand the partly unusual light-curves that many of these objects…

This paper reports a blind search for magnetospheric emissions from planets around nearby stars. Young stars are likely to have much stronger stellar winds than the Sun, and because planetary magnetospheric emissions are powered by stellar…

地球与行星天体物理 · 物理学 2015-05-14 T. Joseph W. Lazio , S. Carmichael , J. Clark , E. Elkins , P. Gudmundsen , Z. Mott , M. Szwajkowski , L. A. Hennig

(Abridged) We investigate the flux density variability and changes in the parsec-scale radio structure of the flat spectrum radio quasar PKS 1510-089. This source was target of multi-epoch VLBI and Space-VLBI observations at 4.8, 8.4 and 22…

宇宙学与河外天体物理 · 物理学 2015-05-28 M. Orienti , T. Venturi , D. Dallacasa , F. D'Ammando , M. Giroletti , G. Giovannini , S. Vercellone , M. Tavani

We present the discovery of strongly variable emission lines from a gaseous disc around the DA white dwarf SDSS J1617+1620, a star previously found to have an infrared excess indicative of a dusty debris disc formed by the tidal disruption…

太阳与恒星天体物理 · 物理学 2015-06-22 David J Wilson , Boris Gaensicke , Detlev Koester , Roberto Raddi , Elmé Breedt , John Southworth , Steven G. Parsons

We have analyzed sensitive high spatial resolution archival radio continuum data at 1.3, 2.0, 3.6 and 6.0 cm as well as the H2O maser molecular line data obtained using the Very Large Array (VLA) in its hybrid AB configuration toward the…

天体物理学 · 物理学 2009-11-13 Luis A. Zapata , Silvia Leurini , Karl M. Menten , Peter Schilke , Rainer Rolffs , Carolin Hieret

We report the detection of circular polarization in the compact radio jet of the nearby spiral galaxy M81 (M81*). The observations were made with the Very Large Array at 4.8 and 8.4 GHz and circular polarization was detected at both…

天体物理学 · 物理学 2009-11-07 A. Brunthaler , G. C. Bower , H. Falcke , R. R. Mellon

Using polarimetric radio profiles of 84 pulsars at a wavelength of 6 cm, we present a correlation between the polarization and characteristic age of pulsars. Considering the large error connected with the value of the characteristic age, we…

天体物理学 · 物理学 2007-05-23 Alexis von Hoensbroech

We report on multi-frequency linear polarization monitoring of 15 active galactic nuclei containing highly relativistic jets with apparent speeds from $\sim$4 $c$ to $>40c$. The measurements were obtained at optical, 1 mm, and 3 mm…

Aims: The ``bright'' High Frequency Peakers (HFPs) sample is a mixture of blazars and intrinsically small and young radio sources. We investigate the polarimetric characteristics of 45 High Frequency Peakers, from the ``bright'' HFP sample,…

天体物理学 · 物理学 2009-11-13 M. Orienti , D. Dallacasa

The Hunting Outbursting Young Stars (HOYS) project performs long-term, optical, multi-filter, high cadence monitoring of 25 nearby young clusters and star forming regions. Utilising Gaia DR3 data we have identified about 17000 potential…

We present the detection of the binary system 2MASS J02132062+3648506 AB using the Karl G. Jansky Very Large Array (VLA) archive data observed at 4-8 GHz. The system is a triple consisting of a tight binary ($\sim0.2"$) of two M dwarfs of…

Polarimetry of the narrow-line radio galaxy PKS 0116+082 at the W.M. Keck telescope shows that it has high and variable optical polarization, presumably due to synchrotron radiation. It is not a BL Lac object because it has strong narrow…

天体物理学 · 物理学 2009-10-30 M. H. Cohen , R. C. Vermeulen , P. M. Ogle , H. D. Tran , R. W. Goodrich

We present simultaneous broad-band radio observations on the abnormal emission mode from PSR B1859$+$07 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). This pulsar shows peculiar emission phenomena, which are…

高能天体物理现象 · 物理学 2022-03-30 Lin Wang , Ye-Zhao Yu , Feifei Kou , Kuo Liu , Xinxin Wang , Bo Peng