Browsing by Author "Williams, Peter"
Now showing items 1-12 of 12
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Discovery of an Outflow from Radio Observations of the Tidal Disruption event ASASSN-14li
Alexander, K. D.; Berger, Edo; Guillochon, J.; Zauderer, B. A.; Williams, Peter Kelsey George (American Astronomical Society, 2016)We report the discovery of transient radio emission from the nearby optically-discovered TDE ASASSN-14li (distance of 90 Mpc), making it the first typical TDE detected in the radio, and unambiguously pointing to the formation ... -
Extragalactic Transients in the Era of Wide-Field Radio Surveys. I. Detection Rates and Light Curve Characteristics
Metzger, Brian D.; Williams, Peter Kelsey George; Berger, Edo (IOP Publishing, 2015)The impending era of wide-field radio surveys has the potential to revolutionize our understanding of astrophysical transients. Here we evaluate the prospects of a wide range of planned and hypothetical radio surveys using ... -
The First Millimeter Detection of a Non-Accreting Ultracool Dwarf
Williams, Peter Kelsey George; Casewell, S. L.; Stark, C. R.; Littlefair, S. P.; Helling, Ch.; Berger, Edo (IOP Publishing, 2015)The well-studied M9 dwarf TVLM 513–46546 is a rapid rotator (Prot ∼ 2 hr) hosting a stable, dipolar magnetic field of ∼3 kG surface strength. Here we report its detection with ALMA at 95 GHz at a mean flux density of 56 ± ... -
Kepler Monitoring of an L Dwarf I. The Photometric Period and White Light Flares
Gizis, John E.; Burgasser, Adam J.; Berger, Edo; Williams, Peter Kelsey George; Vrba, Frederick J.; Cruz, Kelle L.; Metchev, Stanimir (IOP Publishing, 2013)We report on the results of fifteen months of monitoring the nearby field L1 dwarf WISEP J190648.47+401106.8 (W1906+40) with the Kepler mission. Supporting observations with the Karl G. Jansky Very Large Array and Gemini ... -
Kepler Monitoring of an L Dwarf II. Clouds With Multiyear Lifetimes
Gizis, John E.; Dettman, Kyle G.; Burgasser, Adam J.; Camnasio, Sara; Alam, Munazza Khalida; Filippazzo, Joseph C.; Cruz, Kelle L.; Metchev, Stanimir; Berger, Edo; Williams, Peter Kelsey George (IOP Publishing, 2015)We present Kepler, Spitzer Space Telescope, Gemini-North, MMT, and Kitt Peak observations of the L1 dwarf WISEP J190648.47+401106.8. We find that the Kepler optical light curve is consistent in phase and amplitude over the ... -
M Dwarf Activity in the Pan-Starrs1 Medium-Deep Survey: First Catalog and Rotation Periods
Kado-Fong, E.; Williams, Peter Kelsey George; Mann, A.W.; Berger, Edo; Burgett, W.S.; Chambers, K.C.; Huber, M.E.; Kaiser, N.; Kudritzki, R.P.; Magnier, E.A.; Rest, A.; Wainscoat, R.J.; Waters, C. (American Astronomical Society, 2016-12-21)We report on an ongoing project to investigate activity in the M dwarf stellar population observed by the Pan-STARRS 1 Medium Deep Survey (PS1-MDS). Using a custom-built pipeline, we refine an initial sample of ∼4 million ... -
No Precise Localization for Frb 150418: Claimed Radio Transient Is Agn Variability
Williams, Peter Kelsey George; Berger, Edo (American Astronomical Society, 2016)Keane et al. have recently claimed to have obtained the first precise localization for a Fast Radio Burst (FRB) thanks to the identification of a contemporaneous fading slow (∼week-timescale) radio transient. They use this ... -
The Rotation Period and Magnetic Field of the T Dwarf 2massi J1047539+212423 Measured From Periodic Radio Bursts
Williams, Peter Kelsey George; Berger, Edo (IOP Publishing, 2015)Periodic radio bursts from very low mass stars and brown dwarfs simultaneously probe their magnetic and rotational properties. The brown dwarf 2MASSI J1047539+212423 (2M 1047+21) is currently the only T dwarf (T6.5) detected ... -
Simultaneous Multiwavelength Observations of Magnetic Activity in Ultracool Dwarfs. Iv. the Active, Young Binary Nltt 33370 Ab (= 2mass J13142039+1320011)
Williams, Peter Kelsey George; Berger, Edo; Irwin, J.; Berta-Thompson, Z. K.; Charbonneau, David (IOP Publishing, 2015)We present multi-epoch simultaneous radio, optical, Hα, 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 ... -
Trends in Ultracool Dwarf Magnetism. I. X-Ray Suppression and Radio Enhancement
Williams, Peter Kelsey George; Cook, Benjamin Arthur; Berger, Edo (IOP Publishing, 2014)Although ultracool dwarfs (UCDs) are now known to generate and dissipate strong magnetic fields, a clear understanding of the underlying dynamo is still lacking. We have performed X-ray and radio observations of seven UCDs ... -
Trends in Ultracool Dwarf Magnetism. Ii. the Inverse Correlation Between X-Ray Activity and Rotation as Evidence for a Bimodal Dynamo
Cook, Benjamin Arthur; Williams, Peter Kelsey George; Berger, Edo (IOP Publishing, 2014)Observations of magnetic activity indicators in solar-type stars exhibit a relationship with rotation with an increase until a “saturation” level and a moderate decrease in activity in the very fastest rotators ... -
Wisep j060738.65+242953.4: A Nearby Pole-on L8 Brown Dwarf With Radio Emission
Gizis, John E.; Williams, Peter Kelsey George; Burgasser, Adam J.; Libralato, Mattia; Nardiello, Domenico; Piotto, Giampaolo; Bedin, Luigi R.; Berger, Edo; Paudel, Rishi (American Astronomical Society, 2016)We present a simultaneous, multi-wavelength campaign targeting the nearby (7.2 pc) L8/L9 (optical/near-infrared) dwarf WISEP J060738.65+242953.4 in the mid-infrared, radio, and optical. Spitzer Space Telescope observations ...