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We report the detection of periodic (p = 1.96 hours) bursts of extremely bright, 100% circularly polarized, coherent radio emission from the M9 dwarf TVLM 513-46546. Simultaneous photometric monitoring observations have established this…

We performed the new JVLA full polarization observations at 40-48 GHz (6.3-7.5 mm) towards the nearby ($d$ $=$147$\pm$3.4 pc) Class 0 YSO IRAS 16293-2422, and compare with the previous SMA observations reported by Rao et al. (2009; 2014).…

Astrophysics of Galaxies · Physics 2018-09-19 Hauyu Baobab Liu , Yasuhiro Hasegawa , Tao-Chung Ching , Shih-Ping Lai , Naomi Hirano , Ramprasad Rao

We report the detection of strong, highly circularly polarised, and rotationally modulated radio pulses from the early-mid M dwarf ASKAP J181335-604720, based on strictly simultaneous radio and optical observations with the Australian…

Solar and Stellar Astrophysics · Physics 2026-05-18 Shouzhi Wang , Biwei Jiang , Qichen Huang , Shaoteng Huang , Jundan Nie

In this work, we identify 734 ultracool dwarfs with a spectral type of M6 or later, including one L0. Of this sample, 625 were studied spectroscopically for the first time. All of these ultracool dwarfs are within 360~pc, with a…

Solar and Stellar Astrophysics · Physics 2022-04-20 You-Fen Wang , A-Li Luo , Wen-Ping Chen , Hugh R. A. Jones , Bing Du , Yin-Bi Li , Shuo Zhang , Zhong-Rui Bai , Xiao Kong , Yan-Xin Guo

We have obtained projected rotation velocities (vsini) of a sample of 19 ultracool dwarfs with spectral types in the interval M6.5-T8 using high-resolution, near-infrared spectra obtained with NIRSPEC and the Keck II telescope. Among our…

Astrophysics · Physics 2011-02-11 M. R. Zapatero Osorio , E. L. Martin , H. Bouy , R. Tata , R. Deshpande , R. Wainscoat

(abridged) We present high-resolution echelle spectroscopy of a photometricaly-selected sample if thirty-nine dwarfs with spectral types between M6.5 and L0.5. Two stars, 2MASSI 0253202+271333 and 2MASSW 0952219-192431, are double-lined…

Astrophysics · Physics 2010-04-29 I. Neill Reid , J. Davy Kirkpatrick , J. Liebert , J. E. Gizis , C. C. Dahn , D. G. Monet

We present paper six of the NIRSPEC Brown Dwarf Spectroscopic Survey, an analysis of multi-epoch, high-resolution (R~20,000) spectra of 25 field dwarf systems (3 late-type M dwarfs, 16 L dwarfs, and 6 T dwarfs) taken with the NIRSPEC…

Solar and Stellar Astrophysics · Physics 2015-08-06 L. Prato , G. N. Mace , E. L. Rice , I. S. McLean , J. D. Kirkpatrick , A. J. Burgasser , S. S. Kim

We present the detection of 68 sources from the most sensitive radio survey in circular polarisation conducted to date. We use the second data release of the 144 MHz LOFAR Two-metre Sky Survey to produce circularly-polarised maps with…

We present astrometric measurements of eleven nearby ultracool brown dwarfs of spectral types Y and late-T, based on imaging observations from a variety of space-based and ground-based telescopes. These measurements have been used to…

Surveys for nearby low-luminosity dwarfs tend to avoid the crowded regions of the Galactic Plane. We have devised near-infrared colour-magnitude and colour-colour selection criteria designed to identify late-type M and early-type L dwarfs…

Astrophysics · Physics 2009-11-10 I. Neill Reid

We present the results from the first large (>100 source) 3.5 mm polarimetric survey of radio loud active galactic nuclei (AGN). The I, Q, U, and V Stokes parameter observations were performed with the XPOL polarimeter at the IRAM 30m…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 I. Agudo , C. Thum , H. Wiesemeyer , T. P. Krichbaum

Using the Submillimeter Array, we have made the first high angular resolution measurements of the linear polarization of Sagittarius A* at submillimeter wavelengths, and the first detection of intra-day variability in its linear…

Astrophysics · Physics 2009-11-13 D. P. Marrone , J. M. Moran , J. -H. Zhao , R. Rao

We have analyzed the polarization properties of pulsars at an observing frequency of 4.9 GHz. Together with low frequency data, we are able to trace polarization profiles over more than three octaves into an interesting frequency regime. At…

Astrophysics · Physics 2007-05-23 A. von Hoensbroech , J. Kijak , A. Krawczyk

By measuring the polarization changes in THz, infrared, and visible radiation over an extended energy range (3-2330 meV), we observe symmetry-breaking in cuprate high temperature superconductors over wide energy, doping, and temperature…

While there have been multiple observational programs aimed at detecting linear polarization of optical radiation emitted by ultracool dwarfs, there has been comparatively less rigorous theoretical analysis of the problem. The general…

Solar and Stellar Astrophysics · Physics 2014-11-20 Sujan Sengupta , Mark S. Marley

The degree of polarization in L dwarfs of spectral types L0 to L6 resulting from dust scattering in a rotation-induced oblate photosphere is calculated. Assuming that forsterite is the main condensate, the atmospheric dust distribution is…

Astrophysics · Physics 2009-11-10 Sujan Sengupta , Sun Kwok

We investigate the form of the local vertical density profile of the stars in the Galactic disk, close to the Galactic plane. We use a homogeneous sample of 34000 ultracool dwarfs M7 to L2.5 that all lie within 350 pc of the plane. We fit a…

Astrophysics of Galaxies · Physics 2021-06-07 Stephen Warren , Saad Ahmed , Richard Laithwaite

Observations made using TESS revealed a sample of low mass stars which show a periodic modulation on a period $<0.2$~d. Surprisingly many of these Ultra Fast Rotating (UFR) stars showed no evidence of flare activity which would be expected…

Solar and Stellar Astrophysics · Physics 2022-02-23 Gavin Ramsay , Pasi Hakala , J. Gerry Doyle , Lauren Doyle , Stefano Bagnulo

We present optical template spectra, bolometric corrections, and $\chi$ values for ultracool dwarfs. The templates are based on spectra from the Sloan Digital Sky Survey (SDSS) and the Astrophysical Research Consortium 3.5-m telescope. The…

Solar and Stellar Astrophysics · Physics 2015-06-19 Sarah J. Schmidt , Andrew A. West , John J. Bochanski , Suzanne L. Hawley , Collin Kielty

We present the first section of a radio continuum and polarization survey at medium Galactic latitudes carried out with the Effelsberg 100-m telescope at 1.4 GHz. Four large fields have been observed, which all together cover an area of…

Astrophysics · Physics 2009-10-31 B. Uyaniker , E. Fuerst , W. Reich , P. Reich , R. Wielebinski