Results for "Katelyn Breivik"

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Revealing black holes with GaiaOct 12 2017Nov 14 2017We estimate the population of black holes with luminous stellar companions (BH-LCs) in the Milky Way (MW) observable by Gaia. We evolve a realistic distribution of BH-LC progenitors from zero-age to the current epoch taking into account relevant physics, ... More
Shear and depth-averaged Stokes drift under a Phillips-type spectrumMar 21 2016May 27 2016The transport and shear under a Phillips-type spectrum are presented. A combined profile for monochromatic swell and a Phillips-type wind sea spectrum which can be used to investigate the shear under crossing seas is then presented.
Astro2020 Decadal Science White Paper: Gravitational Wave Survey of Galactic Ultra Compact BinariesMar 13 2019Ultra-compact binaries (UCBs) are systems containing compact or degenerate stars with orbital periods less than one hour. Tens of millions of UCBs are predicted to exist within theGalaxy emitting gravitational waves (GWs) at mHz frequencies. Combining ... More
Stellar multiplicity: an interdisciplinary nexusMar 12 2019Our uncertainties about binary star systems (and triples and so on) limit our capabilities in literally every single one of the Thematic Areas identified for Astro2020. We need to understand the population statistics of stellar multiplicity and their ... More
Statistical Inference for Algorithmic LeveragingJun 05 2016Jul 13 2016The age of big data has produced data sets that are computationally expensive to analyze. To deal with such large-scale data sets, the method of algorithmic leveraging proposes that we sample according to some special distribution, rescale the data, and ... More
Confidence Intervals for Algorithmic Leveraging in Linear RegressionJun 05 2016Mar 10 2018The age of big data has produced data sets that are computationally expensive to analyze and store. Algorithmic leveraging proposes that we sample observations from the original data set to generate a representative data set and then perform analysis ... More
Distinguishing Between Formation Channels for Binary Black Holes with LISAJun 30 2016Sep 22 2016The recent detections of GW150914 and GW151226 imply an abundance of stellar-mass binary-black-hole mergers in the local universe. While ground-based gravitational-wave detectors are limited to observing the final moments before a binary merges, space-based ... More
LISA sources in Milky Way globular clustersFeb 15 2018May 30 2018We explore the formation of double-compact-object binaries in Milky Way (MW) globular clusters (GCs) that may be detectable by the Laser Interferometer Space Antenna (LISA). We use a set of 137 fully evolved GC models that, overall, effectively match ... More
An Operational Search and Rescue Model for the Norwegian Sea and the North SeaNov 04 2011A new operational, ensemble-based search and rescue model for the Norwegian Sea and the North Sea is presented. The stochastic trajectory model computes the net motion of a range of search and rescue objects. A new, robust formulation for the relation ... More
Multimessenger science opportunities with mHz gravitational wavesMar 11 2019LISA will open the mHz band of gravitational waves (GWs) to the astronomy community. The strong gravity which powers the variety of GW sources in this band is also crucial in a number of important astrophysical processes at the current frontiers of astronomy. ... More
Approximate Stokes Drift Profiles in Deep WaterJun 19 2014A deep-water approximation to the Stokes drift velocity profile is explored as an alternative to the monochromatic profile. The alternative profile investigated relies on the same two quantities required for the monochromatic profile, viz the Stokes transport ... More
Post-Newtonian Dynamics in Dense Star Clusters: Binary Black Holes in the LISA BandNov 28 2018The dynamical processing of black holes in the dense cores of globular clusters (GCs), makes them efficient factories for producing binary black holes (BBHs). Here we explore the population of BBHs that form dynamically in GCs and may be observable at ... More
Post-Newtonian Dynamics in Dense Star Clusters: Binary Black Holes in the LISA BandNov 28 2018Feb 26 2019The dynamical processing of black holes in the dense cores of globular clusters (GCs), makes them efficient factories for producing binary black holes (BBHs). Here we explore the population of BBHs that form dynamically in GCs and may be observable at ... More
The fate of binaries in the Galactic Center: The Mundane and the ExoticFeb 28 2019The Galactic Center (GC) is dominated by the gravity of a super-massive black hole (SMBH), Sagittarius A$^*$, and is suspected to contain a sizable population of binary stars. Such binaries form hierarchical triples with the SMBH, undergoing Eccentric ... More
Efficient moment calculations for variance components in large unbalanced crossed random effects modelsJan 31 2016Large crossed data sets, described by generalized linear mixed models, have become increasingly common and provide challenges for statistical analysis. At very large sizes it becomes desirable to have the computational costs of estimation, inference and ... More
A Stokes drift approximation based on the Phillips spectrumJan 29 2016Feb 01 2016A new approximation to the Stokes drift velocity profile based on the exact solution for the Phillips spectrum is explored. The profile is compared with the monochromatic profile and the recently proposed exponential integral profile. ERA-Interim spectra ... More
Wind and Wave Extremes over the World Oceans From Very Large Forecast EnsemblesOct 03 2013Global return value estimates of significant wave height and 10-m neutral wind speed are estimated from very large aggregations of archived ECMWF ensemble forecasts at +240-h lead time from the period 2003-2012. The upper percentiles are found to match ... More
Advances in Search and Rescue at SeaNov 05 2012A topical collection on "Advances in Search and Rescue at Sea" has appeared in recent issues of Ocean Dynamics following the latest in a series of workshops on "Technologies for Search and Rescue and other Emergency Marine Operations" (2004, 2006, 2008 ... More
Gorenstein projective precoversJan 10 2016We prove that the class of Gorenstein projective modules is special precovering over any left GF-closed ring such that every Gorenstein projective module is Gorenstein flat and every Gorenstein flat module has finite Gorenstein projective dimension. This ... More
BAKTRAK: Backtracking drifting objects using an iterative algorithm with a forward trajectory modelNov 03 2011The task of determining the origin of a drifting object after it has been located is highly complex due to the uncertainties in drift properties and environmental forcing (wind, waves and surface currents). Usually the origin is inferred by running a ... More
The International Workshop on Wave Hindcasting and Forecasting and the Coastal Hazards SymposiumMar 03 2015Following the 13th International Workshop on Wave Hindcasting and Forecasting and 4th Coastal Hazards Symposium in October 2013 in Banff, Canada, a topical collection has appeared in recent issues of Ocean Dynamics. Here we give a brief overview of the ... More
Wind-induced drift of objects at sea: the leeway field methodNov 03 2011A method for conducting leeway field experiments to establish the drift properties of small objects (0.1-25 m) is described. The objective is to define a standardized and unambiguous procedure for condensing the drift properties down to a set of coefficients ... More
Wave Extremes in the North East Atlantic from Ensemble ForecastsApr 04 2013A method for estimating return values from ensembles of forecasts at advanced lead times is presented. Return values of significant wave height in the North-East Atlantic, the Norwegian Sea and the North Sea are computed from archived +240-h forecasts ... More
A Spitzer Search For Planetary-Mass Brown Dwarfs With Circumstellar Disks: Candidate SelectionAug 09 2010We report on initial results from a Spitzer program to search for very low-mass brown dwarfs in Ophiuchus. This program is an extension of an earlier study by Allers et al. which had resulted in an extraordinary success rate, 18 confirmed out of 19 candidates. ... More
A Keck LGS AO Search for Brown Dwarf and Planetary Mass Companions to Upper Scorpius Brown DwarfsJan 25 2011Jan 27 2011We searched for binary companions to 20 young brown dwarfs in the Upper Scorpius association (145 pc, 5 Myr, nearest OB association) with the the Laser Guide Star adaptive optics system and the facility infrared camera NIRC2 on the 10 m Keck II telescope. ... More
The Hawaii Infrared Parallax Program. II. Young Ultracool Field DwarfsDec 07 2016(Abridged) We present a large, uniform analysis of young (~10-150 Myr) ultracool dwarfs, based on new high-precision IR parallaxes for 68 objects. We find that low-gravity (VL-G) late-M and L dwarfs form a continuous sequence in IR color-magnitude diagrams, ... More
Constraining the multiplicity statistics of the coolest brown dwarfs: binary fraction continues to decrease with spectral typeJun 22 2018Jul 07 2018Binary statistics of the latest-type T and Y brown dwarfs are sparse and it is unclear whether the trends seen in the multiplicity properties of their more massive counterparts hold for the very coolest brown dwarfs. We present results from a search for ... More
Barium Surface Abundances of Blue Stragglers in the Open Cluster NGC 6819Aug 05 2015We present the barium surface abundance of 12 blue stragglers (BSs) and 18 main-sequence (MS) stars in the intermediate-age open cluster NGC 6819 (2.5 Gyr) based on spectra obtained from the Hydra Multi-object Spectrograph on the WIYN 3.5 m telescope. ... More
Simulations of wobble damping in viscoelastic rotatorsJan 05 2019Feb 07 2019Using a damped mass-spring model, we simulate wobble of spinning homogeneous viscoelastic ellipsoids undergoing non-principal axis rotation. Energy damping rates are measured for oblate and prolate bodies with different spin rates, spin states, viscoelastic ... More
Statistical Mechanics of Topological Fluctuations in Glass-Forming LiquidsApr 04 2018All liquids are topologically disordered materials; however, the degree of disorder can vary as a result of internal fluctuations in structure and topology. These fluctuations depend on both the composition and temperature of the system. Most prior work ... More
Wind and Wave Extremes over the World Oceans from Very Large EnsemblesJul 21 2014Global return values of marine wind speed and significant wave height are estimated from very large aggregates of archived ensemble forecasts at +240-h lead time. Long lead time ensures that the forecasts represent independent draws from the model climate. ... More
Infrared Parallaxes of Young Field Brown Dwarfs and Connections to Directly Imaged Gas-Giant ExoplanetsMay 14 2013We have measured high-precision parallaxes for a large sample of candidate young (~10-100 Myr) and intermediate-age (~100-600 Myr) ultracool dwarfs, with spectral types ranging from M8 to T2.5. These objects are compelling benchmarks for substellar evolution ... More
Surface Wave Effects in the NEMO Ocean Model: Forced and Coupled ExperimentsMar 26 2015Apr 07 2015The NEMO general circulation ocean model is extended to incorporate three physical processes related to ocean surface waves, namely the surface stress (modified by growth and dissipation of the oceanic wave field), the turbulent kinetic energy flux from ... More
The Leeway of Shipping Containers at Different Immersion LevelsJan 03 2012The leeway of 20-foot containers in typical distress conditions is established through field experiments in a Norwegian fjord and in open-ocean conditions off the coast of France with wind speed ranging from calm to 14 m/s. The experimental setup is described ... More
R=100,000 Spectroscopy of Photodissociation Regions: H2 Rotational Lines in the Orion BarApr 04 2004Ground state rotational lines of H2 are good temperature probes of moderately hot (200-1000 K) gas. The low A-values of these lines result in low critical densities while ensuring that the lines are optically thin. ISO observations of H2 rotational lines ... More
Nearshore wave forecasting and hindcasting by dynamical and statistical downscalingJun 14 2012A high-resolution nested WAM/SWAN wave model suite aimed at rapidly establishing nearshore wave forecasts as well as a climatology and return values of the local wave conditions with Rapid Enviromental Assessment (REA) in mind is described. The system ... More
A high-resolution hindcast of wind and waves for The North Sea, The Norwegian Sea and The Barents SeaNov 03 2011A combined high-resolution atmospheric downscaling and wave hindcast based on the ERA-40 reanalysis covering the Norwegian Sea, the North Sea and the Barents Sea is presented. The period covered is from September 1957 to August 2002. The dynamic atmospheric ... More
A Stellar Census of the Tucana-Horologium Moving GroupMar 01 2014We report the selection and spectroscopic confirmation of 129 new late-type (K3-M6) members of the Tuc-Hor moving group, a nearby (~40 pc), young (~40 Myr) population of comoving stars. We also report observations for 13/17 known Tuc-Hor members in this ... More
Map of Life: Measuring and Visualizing Species' Relatedness with "Molecular Distance Maps"Jul 14 2013We propose a novel combination of methods that (i) portrays quantitative characteristics of a DNA sequence as an image, (ii) computes distances between these images, and (iii) uses these distances to output a map wherein each sequence is a point in a ... More
Methane in Analogs of Young Directly Imaged ExoplanetsOct 10 2018Nov 22 2018We present detections of methane in R of $\sim$1300, L band spectra of VHS 1256 b and PSO 318.5, two low gravity, red, late L dwarfs that share the same colors as the HR 8799 planets. These spectra reveal shallow methane features, which indicate VHS 1256 ... More
WIYN Open Cluster Study. LX. Spectroscopic Binary Orbits in NGC 6819Aug 01 2014We present the current state of the WOCS radial-velocity (RV) survey for the rich open cluster NGC 6819 (2.5 Gyr) including 93 spectroscopic binary orbits with periods ranging from 1.5 to 8,000 days. These results are the product of our ongoing RV survey ... More
2MASS J13243553+6358281 is an Early T-Type Planetary-Mass Object in the AB Doradus Moving GroupFeb 01 2018We present new radial velocity and trigonometric parallax measurements indicating that the unusually red and photometrically variable T2 dwarf 2MASS J13243553+6358281 is a member of the young (~150 Myr) AB Doradus moving group based on its space velocity. ... More
WIYN Open Cluster Study. LXXI. Spectroscopic Membership and Orbits of NGC 6791 Sub-SubgiantsApr 09 2016In an optical color-magnitude diagram sub-subgiants (SSGs) lie red of the main sequence and fainter than the base of the red giant branch in a region not easily populated by standard stellar-evolution pathways. In this paper, we present multi-epoch radial ... More
On the Binary Frequency of the Lowest Mass Members of the Pleiades with Hubble Space Telescope Wide Field Camera 3May 10 2015We present the results of a Hubble Space Telescope Wide Field Camera 3 imaging survey of 11 of the lowest mass brown dwarfs in the Pleiades known (25-40 Mjup). These objects represent the predecessors to T dwarfs in the field. Using a semi-empirical binary ... More
All-sky Co-moving Recovery Of Nearby Young Members. (ACRONYM) II: The Beta Pictoris Moving GroupJun 14 2017We confirm 66 low-mass stellar and brown dwarf systems (K7-M9) plus 19 visual or spectroscopic companions of the beta Pictoris Moving Group (BPMG). Of these, 41 are new discoveries, increasing the known low-mass members by 45%. We also add four objects ... More
Assessing Generalization in Deep Reinforcement LearningOct 29 2018Deep reinforcement learning (RL) has achieved breakthrough results on many tasks, but has been shown to be sensitive to system changes at test time. As a result, building deep RL agents that generalize has become an active research area. Our aim is to ... More
Fluid heterogeneity detection based on the asymptotic distribution of the time-averaged mean squared displacement in single particle tracking experimentsMay 12 2018Sep 05 2018A tracer particle is called anomalously diffusive if its mean squared displacement grows approximately as $\sigma^2 t^{\alpha}$ as a function of time $t$ for some constant $\sigma^2$, where the diffusion exponent satisfies $\alpha \neq 1$. In this article, ... More
The First Spectrum of the Coldest Brown DwarfMay 16 2016The recently discovered brown dwarf WISE 0855 presents our first opportunity to directly study an object outside the Solar System that is nearly as cold as our own gas giant planets. However the traditional methodology for characterizing brown dwarfs---near ... More
Brown Dwarfs and Directly Imaged Exoplanets in Young AssociationsMar 15 2019In order to understand the atmospheres as well as the formation mechanism of giant planets formed outside our solar system, the next decade will require an investment in studies of isolated young brown dwarfs. In this white paper we summarize the opportunity ... More
Mapping the Space of Genomic SignaturesJun 16 2014Oct 09 2014We propose a computational method to measure and visualize interrelationships among any number of DNA sequences allowing, for example, the examination of hundreds or thousands of complete mitochondrial genomes. An "image distance" is computed for each ... More
A Wide-Field Survey for Transiting Hot Jupiters and Eclipsing Pre-Main-Sequence Binaries in Young Stellar AssociationsJun 09 2016The past two decades have seen a significant advancement in the detection, classification and understanding of exoplanets and binaries. This is due, in large part, to the increase in use of small-aperture telescopes (< 20 cm) to survey large areas of ... More
WISEP J004701.06+680352.1: An intermediate surface gravity, dusty brown dwarf in the AB Dor Moving GroupDec 04 2014We present spectroscopy, astrometry, and photometry of the brown dwarf WISEP J004701.06+680352.1 (W0047+68), an unusually red field L dwarf at a distance of $12.2 \pm 0.4$ parsecs. The three-dimensional space motion identifies it as a member of the AB ... More
Observation and modelling of dusty, low gravity L, and M dwarfsNov 15 2008Observational facilities allow now the detection of optical and IR spectra of young M- and L-dwarfs. This enables empirical comparisons with old M- and L- dwarfs, and detailed studies in comparison with synthetic spectra. While classical stellar atmosphere ... More
Four Faint T Dwarfs from the UKIRT Infrared Deep Sky Survey (UKIDSS) Southern StripeDec 08 2007We present the optical and near-infrared photometry and spectroscopy of four faint T dwarfs newly discovered from the UKIDSS first data release. The sample, drawn from an imaged area of ~136 square degrees to a depth of Y=19.9 (5-sigma, Vega), is located ... More
The Orbits of the Gamma-ray Binaries LS I +61 303 and LS 5039Feb 23 2009Apr 21 2009LS I +61 303 and LS 5039 are two of only a handful of known high mass X-ray binaries (HMXBs) that exhibit very high energy emission in the MeV-TeV range, and these "gamma-ray binaries" are of renewed interest due to the recent launch of the Fermi Gamma-ray ... More
Herschel/PACS view of disks around low-mass stars and brown dwarfs in the TW Hya associationNov 07 2014We conducted Herschel/PACS observations of five very low-mass stars or brown dwarfs located in the TW Hya association with the goal of characterizing the properties of disks in the low stellar mass regime. We detected all five targets at $70\,\mu{\rm{m}}$ ... More
Determining the Age of the Kepler Open Cluster NGC 6819 With a New Triple System and Other Eclipsing Binary StarsJan 15 2016As part of our study of the old (~2.5 Gyr) open cluster NGC 6819 in the Kepler field, we present photometric (Kepler and ground-based BVRcIc) and spectroscopic observations of the detached eclipsing binary WOCS 24009 (Auner 665; KIC 5023948) with a short ... More
A Long-Period Totally Eclipsing Binary Star at the Turnoff of the Open Cluster NGC 6819 Discovered with KeplerNov 12 2012We present the discovery of the totally eclipsing long-period (P = 771.8 d) binary system WOCS 23009 in the old open cluster NGC 6819 that contains both an evolved star near central hydrogen exhaustion and a low-mass (0.45 Msun) star. This system was ... More
WOCS 40007: A Detached Eclipsing Binary near the Turnoff of the Open Cluster NGC 6819Jul 01 2013We analyze extensive BVR_cI_c time-series photometry and radial-velocity measurements for WOCS 40007 (Auner 259; KIC 5113053), a double-lined detached eclipsing binary and a member of the open cluster NGC 6819. Utilizing photometric observations from ... More
Simultaneous, Multi-Wavelength Variability Characterization of the Free-Floating Planetary Mass Object PSO J318.5-22Dec 11 2017We present simultaneous HST WFC3 + Spitzer IRAC variability monitoring for the highly-variable young ($\sim$20 Myr) planetary-mass object PSO J318.5-22. Our simultaneous HST + Spitzer observations covered $\sim$2 rotation periods with Spitzer and most ... More
An L Band Spectrum of the Coldest Brown DwarfApr 20 2018The coldest brown dwarf, WISE 0855, is the closest known planetary-mass, free-floating object and has a temperature nearly as cold as the solar system gas giants. Like Jupiter, it is predicted to have an atmosphere rich in methane, water, and ammonia, ... More
The Extremely Red, Young L Dwarf PSO J318-22: A Free-Floating Planetary-Mass Analog to Directly Imaged Young Gas-Giant PlanetsOct 01 2013Oct 25 2013We have used Pan-STARRS1 to discover an extremely red late-L dwarf, which has (J-K)_MKO = 2.84 and (J-K)_2MASS = 2.78, making it the reddest known field dwarf and second only to 2MASS J1207-39b among substellar companions. Near-IR spectroscopy shows a ... More
A 3 Gyr White Dwarf with Warm Dust Discovered via the Backyard Worlds: Planet 9 Citizen Science ProjectFeb 19 2019Infrared excesses due to dusty disks have been observed orbiting white dwarfs with effective temperatures between 7200 K and 25000 K, suggesting that the rate of tidal disruption of minor bodies massive enough to create a coherent disk declines sharply ... More
A Search for Variability in Exoplanet Analogues and Low-Gravity Brown DwarfsNov 20 2018We report the results of a $J$-band survey for photometric variability in a sample of young, low-gravity objects using the New Technology Telescope (NTT) and the United Kingdom InfraRed Telescope (UKIRT). Surface gravity is a key parameter in the atmospheric ... More
Planets Around Low-Mass Stars (PALMS). V. Age-Dating Low-Mass Companions to Members and Interlopers of Young Moving GroupsMay 06 2015We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8-120 ... More
Variability in a Young, L/T Transition Planetary-Mass ObjectOct 26 2015As part of our ongoing NTT SoFI survey for variability in young free-floating planets and low mass brown dwarfs, we detect significant variability in the young, free-floating planetary mass object PSO J318.5-22, likely due to rotational modulation of ... More
Two Transiting Earth-size Planets Near Resonance Orbiting a Nearby Cool StarJul 29 2015Sep 14 2015Discoveries from the prime Kepler mission demonstrated that small planets (< 3 Earth-radii) are common outcomes of planet formation. While Kepler detected many such planets, all but a handful orbit faint, distant stars and are not amenable to precise ... More