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[Abridged] As part of our on-going investigation of magnetic activity in ultracool dwarfs we present simultaneous radio, X-ray, UV, and optical observations of LSR1835+32 (M8.5), and simultaneous X-ray and UV observations of VB10 (M8), both…

We present initial results of our effort to create a statistically robust, volume-limited sample of ultracool dwarfs from the 2MASS Second Incremental Data Release. We are engaged in a multifaceted search for nearby late-type dwarfs and…

天体物理学 · 物理学 2010-11-04 Kelle L. Cruz , I. Neill Reid , James Liebert , J. Davy Kirkpatrick , Patrick J. Lowrance

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…

太阳与恒星天体物理 · 物理学 2022-02-23 Gavin Ramsay , Pasi Hakala , J. Gerry Doyle , Lauren Doyle , Stefano Bagnulo

Coherent low-frequency ($\lesssim 200$ MHz) radio emission from stars encodes the conditions of the outer corona, mass-ejection events, and space weather. Previous low-frequency searches for radio emitting stellar systems have lacked the…

We present a catalogue of 5306 new ultracool dwarf (UCD) candidates in the three Euclid Deep Fields in the Q1 data release. They range from late M to late T dwarfs, and include 1200 L and T dwarfs. A total of 546 objects have been…

太阳与恒星天体物理 · 物理学 2025-12-10 M. Žerjal , C. Dominguez-Tagle , N. Vitas , N. Sedighi , E. L. Martín , M. R. Zapatero Osorio , J. Olivares , S. Muñoz Torres , S. Tsilia , J. -Y. Zhang , D. Barrado , V. J. S. Béjar , H. Bouy , A. Burgasser , P. Cruz , N. Lodieu , P. Mas Buitrago , N. Phan-Bao , E. Solano , R. Tata , B. Goldman , A. Mohandasan , C. Reylé , R. L. Smart , N. Aghanim , B. Altieri , A. Amara , S. Andreon , N. Auricchio , C. Baccigalupi , M. Baldi , A. Balestra , S. Bardelli , P. Battaglia , A. Biviano , A. Bonchi , E. Branchini , M. Brescia , J. Brinchmann , S. Camera , G. Cañas-Herrera , V. Capobianco , C. Carbone , J. Carretero , S. Casas , M. Castellano , G. Castignani , S. Cavuoti , K. C. Chambers , A. Cimatti , C. Colodro-Conde , G. Congedo , C. J. Conselice , L. Conversi , Y. Copin , F. Courbin , H. M. Courtois , M. Cropper , J. -G. Cuby , A. Da Silva , H. Degaudenzi , G. De Lucia , C. Dolding , H. Dole , M. Douspis , F. Dubath , X. Dupac , S. Dusini , S. Escoffier , M. Farina , F. Faustini , S. Ferriol , S. Fotopoulou , M. Frailis , E. Franceschi , S. Galeotta , K. George , B. Gillis , C. Giocoli , P. Gómez-Alvarez , J. Gracia-Carpio , B. R. Granett , A. Grazian , F. Grupp , S. V. H. Haugan , J. Hoar , W. Holmes , F. Hormuth , A. Hornstrup , K. Jahnke , M. Jhabvala , E. Keihänen , S. Kermiche , A. Kiessling , B. Kubik , K. Kuijken , M. Kümmel , M. Kunz , H. Kurki-Suonio , Q. Le Boulc'h , A. M. C. Le Brun , S. Ligori , P. B. Lilje , V. Lindholm , I. Lloro , G. Mainetti , D. Maino , E. Maiorano , O. Mansutti , O. Marggraf , M. Martinelli , N. Martinet , F. Marulli , R. Massey , E. Medinaceli , S. Mei , Y. Mellier , M. Meneghetti , E. Merlin , G. Meylan , A. Mora , M. Moresco , L. Moscardini , R. Nakajima , C. Neissner , S. -M. Niemi , C. Padilla , S. Paltani , F. Pasian , K. Pedersen , W. J. Percival , V. Pettorino , S. Pires , G. Polenta , M. Poncet , L. A. Popa , L. Pozzetti , F. Raison , R. Rebolo , A. Renzi , J. Rhodes , G. Riccio , E. Romelli , M. Roncarelli , R. Saglia , Z. Sakr , D. Sapone , B. Sartoris , J. A. Schewtschenko , M. Schirmer , P. Schneider , A. Secroun , G. Seidel , M. Seiffert , S. Serrano , P. Simon , C. Sirignano , G. Sirri , L. Stanco , J. Steinwagner , P. Tallada-Crespí , A. N. Taylor , I. Tereno , S. Toft , R. Toledo-Moreo , F. Torradeflot , A. Tsyganov , I. Tutusaus , L. Valenziano , J. Valiviita , T. Vassallo , G. Verdoes Kleijn , A. Veropalumbo , Y. Wang , J. Weller , A. Zacchei , G. Zamorani , F. M. Zerbi , E. Zucca , J. Martín-Fleitas , V. Scottez

The Deeper, Wider, Faster (DWF) program coordinates observations with telescopes across the electromagnetic spectrum, searching for transients on timescales of milliseconds to days. The tenth DWF observing run was carried out in near…

We have used NSF's Karl G. Jansky Very Large Array (VLA) to observe a sample of five known radio-emitting late L and T dwarfs ranging in age from ~0.2 - 3.4Gyr. We observed each target for seven hours, extending to higher frequencies than…

太阳与恒星天体物理 · 物理学 2018-08-09 Melodie Kao , Gregg Hallinan , J. Sebastian Pineda , David Stevenson , Adam Burgasser

The study of radio emission in starburst dwarf galaxies provides a unique opportunity to investigate the mechanisms responsible for the amplification and transport of magnetic fields. Local dwarfs are often considered proxies for…

We present radio observations of 8 ultracool dwarfs with a narrow spectral type range (M8-M9.5) using the Very Large Array at 8.5 GHz. Only the tight M8 binary LP 349-25 was detected. LP 349-25 is the tenth ultracool dwarf system detected…

天体物理学 · 物理学 2008-11-26 N. Phan-Bao , R. A. Osten , J. Lim , E. L. Martin , P. T. P. Ho

We present the detection of 2MASS J22282889-4310262 (2M2228), a T6/T6.5 brown dwarf, using the Karl G. Jansky Very Large Array (VLA) archival data observed at C band (4-8 GHz) over two observing epochs ($2\times96$ minutes). 2M2228 is…

ALFABURST has been searching for Fast Radio Bursts (FRBs) commensally with other projects using the Arecibo L-band Feed Array (ALFA) receiver at the Arecibo Observatory since July 2015. We describe the observing system and report on the…

Magnetic activity in ultracool dwarfs, as measured in X-rays and H$\alpha$, shows a steep decline after spectral type M7-M8. So far, no L dwarf has been detected in X-rays. In contrast, L dwarfs may have higher radio activity than M dwarfs.…

天体物理学 · 物理学 2009-11-13 M. Audard , R. A. Osten , A. Brown , K. R. Briggs , M. Guedel , E. Hodges-Kluck , J. E. Gizis

Recently, a number of ultracool dwarfs have been found to produce periodic radio bursts with high brightness temperature and polarization degree; the emission properties are similar to the auroral radio emissions of the magnetized planets…

太阳与恒星天体物理 · 物理学 2015-06-03 A. A. Kuznetsov , J. G. Doyle , S. Yu , G. Hallinan , A. Antonova , A. Golden

We present multi-epoch simultaneous radio, optical, H{\alpha}, UV, and X-ray observations of the active, young, low-mass binary NLTT 33370 AB (blended spectral type M7e). This system is remarkable for its extreme levels of magnetic…

太阳与恒星天体物理 · 物理学 2015-06-22 P. K. G. Williams , E. Berger , J. Irwin , Z. K. Berta-Thompson , D. Charbonneau

We present the discovery of fifteen new T2.5-T7.5 dwarfs (with estimated distances between ~24-93pc, identified in the first three main data releases of the UKIRT Infrared Deep Sky Survey. This brings the total number of T dwarfs discovered…

A search of the Two Micron All Sky Survey and Sloan Digital Sky Survey reveals 36 previously unknown high proper motion objects with J<17. Their red-optical colors indicate that 27 are M dwarfs, 8 are early-type L dwarfs, and 1 is a…

天体物理学 · 物理学 2009-11-13 Scott S. Sheppard , Michael C. Cushing

The paper presents the results of multi-wave radio observations of sixteen red dwarfs with Earth-like planets in the habitable zones on RATAN-600. In the passage mode, radiometers of four frequency ranges of 22, 11, 4.7 and 2.3 GHz (1.38,…

太阳与恒星天体物理 · 物理学 2025-05-21 Grigory M. Beskin , Vladimir N. Chernenkov , Nikolai N. Bursov , Alexey A. Shlyapnikov , Alexander D. Panov

We present the first simultaneous, multi-wavelength observations of an L dwarf, the L3.5 candidate brown dwarf 2MASS J00361617+1821104, conducted with the Very Large Array, the Chandra X-ray Observatory, and the Kitt Peak 4-m telescope. We…

We report on an unusual radio source J180526-292953, initially identified as a steep spectrum, polarized point source toward the Galactic bulge and found to coincide with the nearby K dwarf HD317101A. We conducted a multi-wavelength radio…

We report the detection of radio emission and orbital motion from the nearby star-brown dwarf binary WISE J072003.20-084651.2AB. Radio observations across the 4.5-6.5 GHz band with the Very Large Array identify at the position of the system…

太阳与恒星天体物理 · 物理学 2015-08-27 Adam J. Burgasser , Carl Melis , Jacob Todd , Christopher R. Gelino , Gregg Hallinan , Daniella Bardalez Gagliuffi