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Observations of variability can provide valuable information about the processes of cloud formation and dissipation in brown dwarf atmospheres. Here we report the results of an independent analysis of archival data from the Brown dwarf…

Solar and Stellar Astrophysics · Physics 2015-06-22 Jacqueline Radigan

Eight optical and four radio observatories have been intensively monitoring the BL Lac object 0716+714 in the last years: 4854 data points have been collected in the UBVRI bands since 1994, while radio light curves extend back to 1978. Many…

Radio observations of cataclysmic variables have revealed a variety of behavior. From some systems, we see bright unpolarized radio flares occurring during dwarf nova outbursts, consistent with synchrotron emission from jets. In others, we…

High Energy Astrophysical Phenomena · Physics 2026-05-05 Margaret E. Ridder , Paul E. Barrett , Craig O. Heinke , Gregory R. Sivakoff

We report on the discovery of one of the most extreme cases of high-frequency radio variability ever measured in active galactic nuclei (AGN), observed on timescales of days and exhibiting variability amplitudes of three to four orders of…

L dwarfs exhibit low-level, rotationally-modulated photometric variability generally associated with heterogeneous, cloud-covered atmospheres. The spectral character of these variations yields insight into the particle sizes and vertical…

Solar and Stellar Astrophysics · Physics 2017-11-15 Everett Schlawin , Adam J. Burgasser , Theodora Karalidi , John Gizis , Johanna Teske

Recent monitoring programs of ultra cool field M and L dwarfs (low mass stars or brown dwarfs) have uncovered low amplitude photometric I-band variations which may be associated with an inhomogeneous distribution of photospheric…

Astrophysics · Physics 2009-11-07 C. A. L. Bailer-Jones , M. Lamm

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…

In this paper, we used the database of the university of Michigan Radio Astronomy Observatory (UMRAO) at three (4.8 GHz, 8.0 GHZ, and 14.5 GHz) radio frequency to analyze the radio light curves by the power spectral analysis method in…

Astrophysics · Physics 2009-11-13 J. H. Fan , Y. Liu , Y. H. Yuan

A wide range of phenomena, from explosive transients to active galactic nuclei, exhibit variability at radio wavelengths on timescales of a few years. Characterizing the rate and scale of variability in the radio sky can provide keen…

Astrophysics of Galaxies · Physics 2026-05-21 Yjan A. Gordon , Peter S. Ferguson , Michael N. Martinez , Eric J. Hooper

Brown dwarfs are classified as objects which are not massive enough to sustain nuclear fusion of hydrogen, and are distinguished from planets by their ability to burn deuterium. Old (>10 Myr) brown dwarfs are expected to possess short-lived…

We describe the arrival time measurements and timing modeling of the periodic radio flares and optical brightness variations of the M9 ultracool dwarf, TVLM 513-46546. We confirm the stability of the observed period and determine its…

Solar and Stellar Astrophysics · Physics 2015-06-19 A. Wolszczan , M. Route

Activities in M dwarfs show spectroscopic variability over various time scales ranging from a few seconds to several hours. The time scales of such variability can be related to internal dynamics of M dwarfs like magnetic activity,…

Solar and Stellar Astrophysics · Physics 2023-02-06 Vipin Kumar , A. S. Rajpurohit , Mudit K. Srivastava

We report the results of a low frequency radio variability and slow transient search using archival observations from the Very Long Array. We selected six 325 MHz radio observations from the spring of 2006, each centered on the…

High Energy Astrophysical Phenomena · Physics 2015-06-04 T. R. Jaeger , S. D. Hyman , N. E. Kassim , T. J. W. Lazio

We report on an analysis of the Extended Chandra Deep Field South (E-CDFS) region using archival data from the Very Large Array, with the goal of studying radio variability and transients at the sub-mJy level. The 49 epochs of E-CDFS…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 K. P. Mooley , D. A. Frail , E. O. Ofek , N. A. Miller , S. R. Kulkarni , A. Horesh

We present the detection of rotationally modulated, circularly polarized radio emission from the T8 brown dwarf WISE J062309.94-045624.6 between 0.9 and 2.0 GHz. We detected this high proper motion ultracool dwarf with the Australian SKA…

We summarize results from flux density monitoring campaigns performed with the 100 meter radio-telescope at Effelsberg and the VLA during the past 15 yrs. We briefly discuss some of the statistical properties of the rapid variability from…

Astrophysics · Physics 2009-11-07 T. P. Krichbaum , A. Kraus , L. Fuhrmann , G. Cimo , A. Witzel

As the sample size of repeating fast radio bursts (FRBs) has grown, an increasing diversity of phenomenology has emerged. Through long-term multi-epoch studies of repeating FRBs, it is possible to assess which phenomena are common to the…

A number of radio-loud ultra cool dwarf stars (UCD) exhibit both continuous broadband and highly polarized pulsed radio emission. In order to determine the nature of the emission and the physical characteristics in the source region, we…

Solar and Stellar Astrophysics · Physics 2015-06-19 C. Lynch , R. L. Mutel , M. Gudel

We present multi-telescope, ground-based, multiwavelength optical and near-infrared photometry of the variable L3.5 ultra-cool dwarf 2MASSW J0036159+182110. We present 22 nights of photometry of 2MASSW J0036159+182110, including 7 nights of…