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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…

Aims. We aim at studying the near infrared linear polarization signal of rapidly rotating ultracool dwarfs with spectral types ranging from M7 through T2 and projected rotational velocities vsini >= 30 km s^{-1}. All these dwarfs are…

太阳与恒星天体物理 · 物理学 2015-06-16 Paulo Alberto Miles-Páez , María Rosa Zapatero Osorio , Enric Pallé , Karla Peña Ramírez

We use data from the first two epochs of the Very Large Array Sky Survey (VLASS) and the IceCube Neutrino Observatory to search for evidence of a correlation between radio variability and the detection of astrophysical neutrinos. We find an…

星系天体物理 · 物理学 2025-11-27 Yjan A. Gordon , Peter S. Ferguson , Eric J. Hooper , Michael N. Martinez

We present a 20-pc, volume-limited sample of M7-L8 dwarfs created through spectroscopic follow-up of sources selected from the Two Micron All Sky Survey (2MASS) Second Incremental Release Point Source Catalog. In this paper, we present…

The radio properties of 11 obscured `radio-intermediate' quasars at redshifts z>~2 have been investigated using the European Very-Long-Baseline-Interferometry Network (EVN) at 1.66 GHz. A sensitivity of ~25 micro Jy per 14x17 mas2 beam was…

宇宙学与河外天体物理 · 物理学 2015-05-13 H. -R. Kloeckner , A. Martinez-Sansigre , S. Rawlings , M. A. Garrett

We conducted a search for brown dwarf candidates in a James Webb Space Telescope deep field around A2744 to investigate the space density of these objects at kiloparsec distances. Our methodology employed an initial selection based on…

太阳与恒星天体物理 · 物理学 2026-02-17 D. H. Li , Z. H. Zhang , H. H. Peng , M. C. Galvez-Ortiz , S. Y. Zhou , H. R. A. Jones

We present a detailed study of radio-detected dwarf galaxies (with stellar masses less than 3 billion solar masses) to characterize extreme star formation and search for (variable) radio AGNs. Our sample comes from Reines et al. (2020)…

星系天体物理 · 物理学 2026-05-01 John-Michael Eberhard , Amy E. Reines

(Abridged). We report on the linear polarimetric observations in the Johnson I filter of 44 M6-L7.5 ultracool dwarfs (2800-1400 K). Eleven (10 L and 1 M) dwarfs appear to have significant linear polarization (P = 0.2-2.5%). We have compared…

天体物理学 · 物理学 2009-11-10 M. R. Zapatero Osorio , J. A. Caballero , V. J. S. Bejar

Over the past few years monitoring programs have shown ultra cool dwarfs (UCDs) to be photometrically variable. Of the 60 sources monitored in the field and some 120 monitored in clusters, about 40% show variability in both cases. For mid…

天体物理学 · 物理学 2007-05-23 C. A. L. Bailer-Jones

We present 1 - 12 GHz Karl G. Jansky Very Large Array observations of 9 off-nuclear persistent radio sources (PRSs) in nearby (z < 0.055) dwarf galaxies, along with high-resolution European very-long baseline interferometry (VLBI) Network…

AIMS: We contribute to improving the census of cool brown dwarfs (late-T and Y dwarfs) in the immediate solar neighbourhood. METHODS: By combining near-infrared (NIR) data of UKIDSS with mid-infrared WISE and other available NIR (2MASS) and…

太阳与恒星天体物理 · 物理学 2015-06-04 Ralf-Dieter Scholz , Gabriel Bihain , Olivier Schnurr , Jesper Storm

Aims: We aim to study the near-infrared variability of the T8 dwarfs 2MASS J09393548-2448279 and EQ J1959-3338 by analyzing their $J$-band photometric signal, which can provide new insights into the atmospheric dynamics of cold brown…

太阳与恒星天体物理 · 物理学 2025-04-30 P. A. Miles-Páez , S. Metchev , M. R. Zapatero Osorio , D. Martín-Carrero

We present first results from a targeted search for brown dwarfs with unusual red colors indicative of peculiar atmospheric characteristics. These include objects with low surface gravities or with unusual dust content or cloud properties.…

太阳与恒星天体物理 · 物理学 2015-12-02 Kendra Kellogg , Stanimir Metchev , Kerstin Geissler , Shannon Hicks , J. Davy Kirkpatrick , Radostin Kurtev

We report the discovery of a very cool, isolated brown dwarf, UGPS 0722-05, with the UKIDSS Galactic Plane Survey. The near-infrared spectrum displays deeper H2O and CH4 troughs than the coolest known T dwarfs and an unidentified absorption…

Scallop-shell stars, a recently discovered class of young M dwarfs, show complex optical light curves that are characterized by periodic dips as well as other features that are stable over tens to hundreds of rotation cycles. The origin of…

*Abbreviated abstract* Context: Brown dwarfs in the spectral range L9-T3.5, within the so called L/T transition, have been shown to be variable at higher amplitudes and with greater frequency than other field dwarfs. [...] Now, more…

地球与行星天体物理 · 物理学 2019-11-04 Simon C. Eriksson , Markus Janson , Per Calissendorff

Recent work has exploited pulsar survey data to identify temporally isolated, millisecond-duration radio bursts with large dispersion measures (DMs). These bursts have been interpreted as arising from a population of extragalactic sources,…

In order to understand the possible mechanisms of recurrent jet activity in radio galaxies and quasars, which are still unclear, we have identified such sources with a large range of linear sizes (220 $-$ 917 kpc), and hence time scales of…

星系天体物理 · 物理学 2019-07-17 S. Nandi , D. J. Saikia , R. Roy , P. Dabhade , Y. Wadadekar , J. Larsson , M. Baes , H. C. Chandola , M. Singh

A significant minority of high redshift radio galaxy (HzRG) candidates show extremely red broad band colours and remain undetected in emission lines after optical `discovery' spectroscopy. In this paper we present deep GTC optical imaging…

We report the discovery of 47 new T dwarfs in the Fourth Data Release (DR4) from the Large Area Survey (LAS) of the UKIRT Infrared Deep Sky Survey with spectral types ranging from T0 to T8.5. These bring the total sample of LAS T dwarfs to…