Results for "Keivan G. Stassun"

total 110675took 0.17s
Evidence for a systematic offset of $-$0.25 mas in the Gaia DR1 parallaxes at $π\gtrsim 1$ masSep 17 2016Sep 21 2016We test the parallaxes reported in the Gaia first data release using the sample of eclipsing binaries with accurate, empirical distances from Stassun \& Torres (2016). We find a clear average offset of $-$0.25$\pm$0.05~mas in the sense of the Gaia parallaxes ... More
Temporal Evolution of Chromospheric Oscillations in Flaring Regions - A Pilot StudyMar 07 2018We have analyzed H-alpha intensity images obtained at a 1 minute cadence with the Global Oscillation Network Group (GONG) system to investigate the properties of oscillations in the 0-8 mHz frequency band at the location and time of strong M- and X-class ... More
AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light CurvesJan 11 2016Jan 17 2017ImageJ is a graphical user interface (GUI) driven, public domain, Java-based, software package for general image processing traditionally used mainly in life sciences fields. The image processing capabilities of ImageJ are useful and extendable to other ... More
A Survey for a Coeval, Comoving Group Associated with HD 141569Sep 19 2008We present results of a search for a young stellar moving group associated with the star HD 141569, a nearby, isolated Herbig AeBe primary member of a 5+/-3 Myr-old triple star system on the outskirts of the Sco-Cen complex. Our spectroscopic survey identified ... More
AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves (Expanded Edition)Jan 17 2017ImageJ is a graphical user interface (GUI) driven, public domain, Java-based, software package for general image processing traditionally used mainly in life sciences fields. The image processing capabilities of ImageJ are useful and extendable to other ... More
Evidence for Binarity and Possible Disk Obscuration in Kepler Observations of the Pulsating RV Tau Variable DF CygniMar 24 2017Apr 14 2017The Kepler light curve of DF Cyg is unparalleled in precision and cadence for any RV Tau star to date spanning a baseline of $\sim$4 years and clearly displaying the signature pulsating behavior of alternating deep and shallow minima as well as the long-term ... More
The DEdicated MONitor of EXotransits and Transients (DEMONEXT): System Overview and Year One Results from a Low-Cost Robotic Telescope for Follow-Up of Exoplanetary Transits and TransientsSep 15 2017We report on the design and first year of operations of the DEdicated MONitor of EXotransits and Transients (DEMONEXT). DEMONEXT is a 20 inch (0.5-m) robotic telescope using a PlaneWave CDK20 telescope on a Mathis instruments MI-750/1000 fork mount. DEMONEXT ... More
Near-Infrared Emission Spectrum of WASP-103b using Hubble Space Telescope/Wide Field Camera 3Nov 28 2016Jan 10 2017We present here our observations and analysis of the dayside emission spectrum of the hot Jupiter WASP-103b. We observed WASP-103b during secondary eclipse using two visits of the Hubble Space Telescope with the G141 grism on Wide Field Camera 3 in spatial ... More
Variability Properties of 4 Million Sources in the $TESS$ Input Catalog Observed with the Kilodegree Extremely Little Telescope SurveyNov 09 2017The Kilodegree Extremely Little Telescope (KELT) has been surveying more than $70\%$ of the celestial sphere for nearly a decade. While the primary science goal of the survey is the discovery of transiting, large-radii planets around bright host stars, ... More
The Monitor project: tracking the evolution of low mass and pre-main sequence starsNov 06 2007The Monitor project is a large-scale program of photometric and spectroscopic monitoring of young open clusters using telescopes at ESO and other observatories. Its primary goal is to detect and characterise new low-mass eclipsing binaries, and the first ... More
Kepler-503b: An Object at the Hydrogen Burning Mass Limit Orbiting a Subgiant StarMay 22 2018Jun 11 2018Using spectroscopic radial velocities with the APOGEE instrument and Gaia distance estimates, we demonstrate that Kepler-503b, currently considered a validated Kepler planet, is in fact a brown-dwarf/low-mass star in a nearly circular 7.2-day orbit around ... More
Discovery of a Transiting Planet Near the Snow-LineJul 17 2014In most theories of planet formation, the snow-line represents a boundary between the emergence of the interior rocky planets and the exterior ice giants. The wide separation of the snow-line makes the discovery of transiting worlds challenging, yet transits ... More
Mid-infrared characterization of the planetary-mass companion ROXs 42B bFeb 21 2017Mar 02 2017We present new Keck/NIRC2 3$-$5 $\mu$m infrared photometry of the planetary-mass companion to ROXS 42B in $L^\prime$, and for the first time in Brackett-$\alpha$ (Br$\alpha$) and in $M_\mathrm{s}$-band. We combine our data with existing near-infrared ... More
A Direct Measurement with Gaia of Radius Inflation in the Pleiades and its Relation to Rotation and Lithium DepletionSep 15 2016Sep 20 2016Boutique measurements of eclipsing binary parameters and statistical studies of young clusters have suggested that some magnetically active low-mass dwarfs possess radii inflated by $\sim$5-15% relative to theoretical expectations. If true, this effect ... More
High-Resolution Spectroscopy during Eclipse of the Young Substellar Eclipsing Binary 2MASS 0535-0546. II. Secondary Spectrum: No Evidence that Spots Cause the Temperature ReversalAug 01 2012Aug 13 2012We present high-resolution optical spectra of the young brown-dwarf eclipsing binary 2M0535-05, obtained during eclipse of the higher-mass (primary) brown dwarf. Combined with our previous spectrum of the primary alone (Paper I), the new observations ... More
Angular Momentum Evolution of Young Stars: Toward a Synthesis of Observations, Theory, and ModelingMar 17 2003The aim of this AAS Topical Session was to update the community on the current state of knowledge about the angular momentum evolution of young stars. For newcomers to the subject, the session was intended to provide an introduction and general overview ... More
Evidence for a systematic offset of $-$0.25 mas in the Gaia DR1 parallaxesSep 17 2016Oct 13 2016We test the parallaxes reported in the Gaia first data release using the sample of eclipsing binaries with accurate, empirical distances from Stassun \& Torres (2016). We find an average offset of $-$0.25$\pm$0.05 mas in the sense of the Gaia parallaxes ... More
Magnetic Accretion and Photopolarimetric Variability in Classical T Tauri StarsAug 24 1998We employ a Monte Carlo radiation transfer code to investigate the multi- wavelength photopolarimetric variability arising from a spotted T Tauri star surrounded by a dusty circumstellar disk. Our aim is to assess the ability of the magnetic accretion ... More
Evidence for a systematic offset of -80 micro-arcseconds in the Gaia DR2 parallaxesMay 08 2018Jun 05 2018We reprise the analysis of Stassun & Torres (2016), comparing the parallaxes of the eclipsing binaries reported in that paper to the parallaxes newly reported in the Gaia second data release (DR2). We find evidence for a systematic offset of $-82 \pm ... More
The canonical Luminous Blue Variable AG Car and its neighbor Hen 3-519 are much closer than previously assumedOct 20 2016The strong mass loss of Luminous Blue Variables (LBVs) is thought to play a critical role in the evolution of massive stars, but the physics of their instability and their place in the evolutionary sequence remains uncertain and debated. A key to understanding ... More
Eclipsing Binary Stars as Benchmarks for Trigonometric Parallaxes in the Gaia EraSep 08 2016We present fits to the broadband photometric spectral energy distributions (SEDs) of 158 eclipsing binaries (EBs) in the Tycho-2 catalog. These EBs were selected because they have highly precise stellar radii, effective temperatures, and in many cases ... More
Time-Series Photometry of Stars in and around the Lagoon Nebula. I. Rotation Periods of 290 Low-Mass Pre-Main-Sequence Stars in NGC 6530Dec 09 2011Dec 31 2011We have conducted a long-term, wide-field, high-cadence photometric monitoring survey of ~50,000 stars in the Lagoon Nebula \ion{H}{2} region. This first paper presents rotation periods for 290 low-mass stars in NGC 6530, the young cluster illuminating ... More
Extreme Debris Disk Variability -- Exploring the Diverse Outcomes of Large Asteroid Impacts During the Era of Terrestrial Planet FormationMar 25 2019Apr 19 2019The most dramatic phases of terrestrial planet formation are thought to be oligarchic and chaotic growth, on timescales of up to 100-200 Myr, when violent impacts occur between large planetesimals of sizes up to proto-planets. Such events are marked by ... More
VISION: A Six-Telescope Fiber-Fed Visible Light Beam Combiner for the Navy Precision Optical InterferometerJan 01 2016Visible-light long baseline interferometry holds the promise of advancing a number of important applications in fundamental astronomy, including the direct measurement of the angular diameters and oblateness of stars, and the direct measurement of the ... More
IN-SYNC I: Homogeneous Stellar Parameters from High Resolution APOGEE Spectra for Thousands of Pre-main Sequence StarAug 29 2014Over two years 8,859 high-resolution H-band spectra of 3,493 young (1 - 10 Myr) stars were gathered by the multi-object spectrograph of the APOGEE project as part of the IN-SYNC ancillary program of that SDSS-III survey. Here we present the forward modeling ... More
IN-SYNC IV - The Young Stellar Population in the Orion A Molecular CloudNov 13 2015Dec 10 2015We present the results of the SDSS APOGEE INfrared Spectroscopy of Young Nebulous Clusters program (IN-SYNC) survey of the Orion A molecular cloud. This survey obtained high resolution near infrared (NIR) spectroscopy of about 2700 young pre-main sequence ... More
Expected Large Synoptic Survey Telescope (LSST) Yield of Eclipsing Binary StarsMay 30 2011In this paper we estimate the Large Synoptic Survey Telescope (LSST) yield of eclipsing binary stars, which will survey ~20,000 square degrees of the southern sky during the period of 10 years in 6 photometric passbands to r ~ 24.5. We generate a set ... More
Predicting Granulation "Flicker" and Radial Velocity "Jitter" from Spectroscopic ObservablesDec 10 2018Surface granulation can be predicted with the mass, metallicity, and frequency of maximum power of a star. Using the orders-of-magnitude larger APOGEE-Kepler sample, we recalibrate the relationship fit by Corsaro et al. (2017) for "flicker", an easier-to-compute ... More
Opening the Treasure Chest: A Newborn Star Cluster Emerges from its Dust Pillar in CarinaNov 08 2004We present detailed observations of the Treasure Chest, a compact nebula at the head of a dust pillar in the southern Carina nebula. This object is of interest because it is an example of a dense young cluster containing at least one massive star, the ... More
The EB Factory Project. II. Validation with the Kepler Field in Preparation for K2 and TESSSep 10 2014Large repositories of high precision light curve data, such as the Kepler data set, provide the opportunity to identify astrophysically important eclipsing binary (EB) systems in large quantities. However, the rate of classical "by eye" human analysis ... More
Precision Light Curves from TESS Full-Frame Images: A Difference Imaging ApproachMar 06 2018The Transiting Exoplanet Survey Satellite (TESS) will observe $\sim$150~million stars brighter than $T_{\rm mag} \approx 16$, with photometric precision from 60~ppm to 3~percent, enabling an array of exoplanet and stellar astrophysics investigations.While ... More
A Multi-Year Search For Transits Of Proxima Centauri. II: No Evidence For Transit Events With Periods Between 1-30 DaysJan 21 2019Apr 08 2019Using a global network of small telescopes, we have obtained light curves of Proxima Centauri at 329 observation epochs from 2006 - 2017. The planet Proxima b discovered by Anglada-Escude et al. (2016) with an orbital period of 11.186 d has an a priori ... More
A Compact Multi-Planet System With A Significantly Misaligned Ultra Short Period PlanetJun 21 2018Oct 29 2018We report the discovery of a compact multi-planet system orbiting the relatively nearby (78pc) and bright ($K=8.9$) K-star, K2-266 (EPIC248435473). We identify up to six possible planets orbiting K2-266 with estimated periods of P$_b$ = 0.66, P$_{.02}$ ... More
A Multi-Year Search For Transits Of Proxima Centauri. I: Light Curves Corresponding To Published EphemeridesFeb 12 2018May 14 2018Proxima Centauri has become the subject of intense study since the radial-velocity discovery by Anglada-Escud\'e et al. 2016 of a planet orbiting this nearby M-dwarf every ~ 11.2 days. If Proxima Centauri b transits its host star, independent confirmation ... More
Two warm, low-density sub-Jovian planets orbiting bright stars in K2 campaigns 13 and 14Mar 07 2018Jul 28 2018We report the discovery of two planets transiting the bright stars HD 89345 (EPIC 248777106, $V=9.376$, $K=7.721$) in K2 Campaign 14 and HD 286123 (EPIC 247098361, $V=9.822$, $K=8.434$) in K2 Campaign 13. Both stars are G-type stars, one of which is at ... More
Close companions around young starsMar 25 2019Mar 27 2019Multiplicity is a fundamental property that is set early during stellar lifetimes, and it is a stringent probe of the physics of star formation. The distribution of close companions around young stars is still poorly constrained by observations. We present ... More
Testing the Asteroseismic Mass Scale Using Metal-Poor Stars Characterized with APOGEE and KeplerMar 07 2014Fundamental stellar properties, such as mass, radius, and age, can be inferred using asteroseismology. Cool stars with convective envelopes have turbulent motions that can stochastically drive and damp pulsations. The properties of the oscillation frequency ... More
Transiting Planets with LSST I: Potential for LSST Exoplanet DetectionAug 11 2014Oct 24 2014The Large Synoptic Survey Telescope (LSST) has been designed in order to satisfy several different scientific objectives that can be addressed by a ten-year synoptic sky survey. However, LSST will also provide a large amount of data that can then be exploited ... More
An observational correlation between stellar brightness variations and surface gravityAug 21 2013Surface gravity is one of a star's basic properties, but it is difficult to measure accurately, with typical uncertainties of 25-50 per cent if measured spectroscopically and 90-150 per cent photometrically. Asteroseismology measures gravity with an uncertainty ... More
The Impact of Chromospheric Activity on Observed Initial Mass FunctionsOct 18 2014Oct 21 2014Using recently established empirical calibrations for the impact of chromospheric activity on the radii, effective temperatures, and estimated masses of active low-mass stars and brown dwarfs, we reassess the shape of the initial mass function (IMF) across ... More
Spectral Energy Distributions of Young Stars in IC 348: The Role of Disks in Angular Momentum Evolution of Young, Low-Mass StarsJun 07 2011Jun 14 2011Theoretical work suggests that a young star's angular momentum and rotation rate may be strongly influenced by magnetic interactions with its circumstellar disk. A generic prediction of these 'disk-locking' (DL) theories is that a disk-locked star will ... More
Transit Timing Variation Measurements of WASP-12b and Qatar-1b: No Evidence for Additional PlanetsDec 01 2015Aug 23 2016WASP-12b and Qatar-1b are transiting Hot Jupiters for which previous works have suggested the presence of transit timing variations (TTVs) indicative of additional bodies in these systems - an Earth-mass planet in WASP-12 and a brown-dwarf mass object ... More
Circumstellar Environment and Effective Temperature of the Young Substellar Eclipsing Binary 2MASS J05352184-0546085Mar 11 2009We present new Spitzer IRAC/PU/MIPS photometry from 3.6 to 24 um, and new Gemini GMOS photometry at 0.48 um, of the young brown dwarf eclipsing binary 2MASS J05352184-0546085, located in the Orion Nebula Cluster. No excess disk emission is detected: The ... More
Planetary Nebulae and How to Find Them: Color Identification in Big Broadband SurveysMay 15 2019Planetary nebulae (PNe) provide tests of stellar evolution, can serve as tracers of chemical evolution in the Milky Way and other galaxies, and are also used as a calibrator of the cosmological distance ladder. Current and upcoming large scale photometric ... More
Accurate, Empirical Radii and Masses of Planets with Gaia ParallaxesSep 14 2016Sep 15 2016We present new, empirical measurements of the radii of 132 stars that host transiting planets. These stellar radii are determined using only direct observables---the bolometric flux at Earth, the stellar effective temperature, and the parallax newly provided ... More
A Granulation "Flicker"-based Measure of Stellar Surface GravityDec 10 2015In Bastien et al. (2013) we found that high quality light curves, such as those obtained by Kepler, may be used to measure stellar surface gravity via granulation-driven light curve "flicker". Here, we update and extend the relation originally presented ... More
Observations of the M82 SN 2014J with the Kilodegree Extremely Little TelescopeNov 15 2014We report observations of the bright M82 supernova 2014J serendipitously obtained with the Kilodegree Extremely Little Telescope (KELT). The SN was observed at high cadence for over 100 days, from pre-explosion, to early rise and peak times, through the ... More
Empirical Tests of Pre-Main-Sequence Stellar Evolution Models with Eclipsing BinariesJun 15 2014We examine the performance of standard PMS stellar evolution models against the accurately measured properties of a benchmark sample of 26 PMS stars in 13 EB systems. We provide a definitive compilation of all fundamental properties for the EBs. We also ... More
Gaia Assorted Mass Binaries Long Excluded from SLoWPoKES (GAMBLES): Identifying Wide Binary Pairs with Components of Diverse MassNov 23 2016Despite the maturity of stellar astrophysics, the formation and evolution of binary star systems still remain key questions in modern astronomy. Wide binary pairs (separations >10^3 AU) are particularly intriguing because their low binding energies makes ... More
Stellar Rotation in M35: Mass-Period Relations, Spin-Down Rates, and GyrochronologyMay 07 2008Nov 26 2008We present the results of a 5 month photometric time-series survey for stellar rotation over a 40'x40' field on the 150 Myr open cluster M35. We report rotation periods for 441 stars and determine their cluster membership and binarity based on a decade-long ... More
An Observational Study of Tidal Synchronization in Solar-Type Binary Stars in the Open Clusters M35 and M34Aug 07 2006We present rotation periods for the solar-type primary stars in 13 close (a~< 5 AU) single-lined spectroscopic binaries with known orbital periods (P) and eccentricities (e). All binaries are members of the open clusters M35 (150Myr) and M34 (250Myr). ... More
Accurate, Empirical Radii and Masses of Planets and their Host Stars with Gaia ParallaxesSep 14 2016Feb 01 2017We present empirical measurements of the radii of 116 stars that host transiting planets. These radii are determined using only direct observables-the bolometric flux at Earth, the effective temperature, and the parallax provided by the Gaia first data ... More
A Search for Star-Disk Interaction Among the Strongest X-ray Flaring Stars in the Orion Nebula ClusterMay 12 2010The Chandra Orion Ultradeep Project observed hundreds of young, low-mass stars undergoing highly energetic X-ray flare events. The 32 most powerful cases have been modeled with the result that the magnetic structures responsible for these flares can be ... More
AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light CurvesJan 11 2016ImageJ is a graphical user interface (GUI) driven, public domain, Java-based, software package for general image processing traditionally used mainly in life sciences fields. The image processing capabilities of ImageJ are useful and extendable to other ... More
Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet Host StarsMay 05 2014Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the ... More
Gaia Assorted Mass Binaries Long Excluded from SLoWPoKES (GAMBLES): Identifying Wide Binary Pairs with Components of Diverse MassNov 23 2016Nov 27 2016Despite the maturity of stellar astrophysics, the formation and evolution of binary star systems still remain key questions in modern astronomy. Wide binary pairs (separations >10^3 AU) are particularly intriguing because their low binding energies makes ... More
Empirical, Accurate Masses and Radii of Single Stars with TESS and GaiaOct 04 2017Nov 07 2017We present a methodology for the determination of empirical masses of single stars through the combination of three direct observables with Gaia and TESS: (i) the surface gravity via granulation-driven variations in the TESS light curve, (ii) the bolometric ... More
Gaia Assorted Mass Binaries Long Excluded from SLoWPoKES (GAMBLES): Identifying Ultra-Wide Binary Pairs with Components of Diverse MassNov 23 2016Apr 14 2017The formation and evolution of binary star systems still remain key questions in modern astronomy. Wide binary pairs (separations $>10^3$ AU) are particularly intriguing because their low binding energies make it difficult for the stars to stay gravitationally ... More
High Cadence Time-Series Photometry of V1647 OrionisAug 27 2011We present high cadence (1-10 hr^-1) time-series photometry of the eruptive young variable star V1647 Orionis during its 2003-2004 and 2008-2009 outbursts. The 2003 light curve was obtained mid-outburst at the phase of steepest luminosity increase of ... More
First Results from the Disk Eclipse Search with KELT (DESK) SurveySep 14 2015Using time-series photometry from the Kilodegree Extremely Little Telescope (KELT) exoplanet survey, we are looking for eclipses of stars by their protoplanetary disks, specifically in young stellar associations. To date, we have discovered two previously ... More
Eclipsing Binary Stars as Tests of Stellar Evolutionary Models and Stellar AgesFeb 16 2009Eclipsing binary stars provide highly accurate measurements of the fundamental physical properties of stars. They therefore serve as stringent tests of the predictions of evolutionary models upon which most stellar age determinations are based. Models ... More
A Surprising Reversal of Temperatures in the Brown-Dwarf Eclipsing Binary 2MASS J05352184-0546085Apr 24 2007The newly discovered brown-dwarf eclipsing binary 2MASS J05352184-0546085 provides a unique laboratory for testing the predictions of theoretical models of brown-dwarf formation and evolution. The finding that the lower-mass brown dwarf in this system ... More
Reanalysis of the Radii of the Benchmark Eclipsing Binary V578 MonApr 04 2013V578 Mon is an eclipsing binary system in which both stars have masses above 10 Msun determined with an accuracy better than 3%. It is one of only five such massive eclipsing binaries known that also possess eccentric orbits and measured apsidal motions, ... More
High Resolution Spectroscopy during Eclipse of the Young Substellar Eclipsing Binary 2MASS 0535-0546. I. Primary Spectrum: Cool Spots versus Opacity UncertaintiesAug 13 2010We present high-resolution Keck optical spectra of the very young substellar eclipsing binary 2MASS J05352184-0546085, obtained during eclipse of the lower-mass (secondary) brown dwarf. The observations yield the spectrum of the higher-mass (primary) ... More
KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectraMay 25 2015Sep 26 2015We announce the discovery of a highly inflated transiting hot Jupiter discovered by the KELT-North survey. A global analysis including constraints from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly evolved, G dwarf with $T_{\rm ... More
KELT-10b: The First Transiting Exoplanet from the KELT-South Survey -- A Hot Sub-Jupiter Transiting a V = 10.7 Early G-StarSep 08 2015Jul 24 2016We report the discovery of KELT-10b, the first transiting exoplanet discovered using the KELT-South telescope. KELT-10b is a highly inflated sub-Jupiter mass planet transiting a relatively bright $V = 10.7$ star (TYC 8378-64-1), with T$_{eff}$ = $5948\pm74$ ... More
KELT-3b: A Hot Jupiter Transiting a V=9.8 Late-F StarNov 05 2012Jun 04 2013We report the discovery of KELT-3b, a moderately inflated transiting hot Jupiter with a mass of 1.477 (-0.067, +0.066) M_J, and radius of 1.345 +/- 0.072 R_J, with an orbital period of 2.7033904 +/- 0.000010 days. The host star, KELT-3, is a V=9.8 late ... More
KELT-1b: A Strongly Irradiated, Highly Inflated, Short Period, 27 Jupiter-mass Companion Transiting a mid-F StarJun 07 2012We present the discovery of KELT-1b, the first transiting low-mass companion from the wide-field Kilodegree Extremely Little Telescope-North (KELT-North) survey. The V=10.7 primary is a mildly evolved, solar-metallicity, mid-F star. The companion is a ... More
Global Climate and Atmospheric Composition of the Ultra-Hot Jupiter WASP-103b from HST and Spitzer Phase Curve ObservationsApr 30 2018Jun 06 2018We present thermal phase curve measurements for the hot Jupiter WASP-103b observed with Hubble/WFC3 and Spitzer/IRAC. The phase curves have large amplitudes and negligible hotspot offsets, indicative of poor heat redistribution to the nightside. We fit ... More
KELT-7b: A hot Jupiter transiting a bright V=8.54 rapidly rotating F-starJan 22 2015May 19 2015We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of $1.28 \pm 0.18$ MJ, radius of $1.53_{-0.047}^{+0.046}$ RJ, and an orbital period of $2.7347749 \pm 0.0000039$ days. The bright host star (HD33643; KELT-7) is an F-star with $V=8.54$, ... More
A Framework for Prioritizing the TESS Planetary Candidates Most Amenable to Atmospheric CharacterizationMay 09 2018Sep 14 2018A key legacy of the recently launched TESS mission will be to provide the astronomical community with many of the best transiting exoplanet targets for atmospheric characterization. However, time is of the essence to take full advantage of this opportunity. ... More
TESS Spots a Compact System of Super-Earths around the Naked-Eye Star HR 858May 13 2019May 15 2019Transiting Exoplanet Survey Satellite (TESS) observations have revealed a compact multi-planet system around the sixth-magnitude star HR 858 (TIC 178155732), located 32 parsecs away. Three planets, each about twice the size of Earth, transit this slightly-evolved, ... More
Transiting Planets with LSST II. Period Detection of Planets Orbiting 1 Solar Mass HostsFeb 28 2015Jul 23 2015The Large Synoptic Survey Telescope (LSST) will photometrically monitor approximately 1 billion stars for ten years. The resulting light curves can be used to detect transiting exoplanets. In particular, as demonstrated by Lund et al. (2015), LSST will ... More
New BVIc Photometry of Low-mass Pleiades Stars: Exploring the Effects of Rotation on Broadband ColorsJul 01 2014We present new BVIc photometry for 350 Pleiades proper-motion members with 9 < V < 17. Importantly, our new catalog includes a large number of K and early-M type stars, roughly doubling the number of low-mass stars with well calibrated Johnson/Cousins ... More
Resolved Spectroscopy of M Dwarf/L Dwarf Binaries. IV. Discovery of an M9 + L6 BInary Separated by Over 100 AUOct 06 2010Oct 11 2010We report the discovery of a faint L6 \pm 1 companion to the previously known M9 dwarf, 2MASS J01303563-4445411, based on our near-infrared imaging and spectroscopic observations with the 3m Infrared Telescope Facility SpeX imager/spectrometer. The visual ... More
Transiting Planets with LSST IV: Detecting Planets around White DwarfsSep 28 2018Previous work has demonstrated that the Large Synoptic Survey Telescope (LSST) has the capability to detect transiting planets around main sequence stars in relatively short ($<$ 20 days) periods and using standard algorithms for transit detection and ... More
What Does a Successful Postdoctoral Fellowship Publication Record Look Like?Oct 22 2018Oct 24 2018Obtaining a prize postdoctoral fellowship in astronomy and astrophysics involves a number of factors, many of which cannot be quantified. One criterion that can be measured is the publication record of an applicant. The publication records of past fellowship ... More
Correcting for Activity Effects on the Temperatures, Radii, and Estimated Masses of Low-Mass Stars and Brown DwarfsSep 08 2012We present empirical relations for determining the amount by which the effective temperatures and radii---and therefore the estimated masses---of low-mass stars and brown dwarfs are altered due to chromospheric activity. Accurate estimates of stellar ... More
Dynamical Mass Constraints on Low-Mass Pre-Main-Sequence Stellar Evolutionary Tracks: An Eclipsing Binary in Orion with a 1.0 Msun Primary and an 0.7 Msun SecondaryDec 22 2003We report the discovery of a double-lined, spectroscopic, eclipsing binary in the Orion star-forming region. We analyze the system spectroscopically and photometrically to empirically determine precise, distance-independent masses, radii, effective temperatures, ... More
A 10-micron Search for Inner-Truncated Disks Among Pre-Main-Sequence Stars With Photometric Rotation PeriodsOct 31 2000We use mid-IR (primarily 10 $\mu$m) photometry as a diagnostic for the presence of disks with inner cavities among 32 pre-main sequence stars in Orion and Taurus-Auriga for which rotation periods are known and which do not show evidence for inner disks ... More
Stellar Granulation as the Source of High-Frequency Flicker in Kepler Light CurvesDec 20 2013A large fraction of cool, low-mass stars exhibit brightness fluctuations that arise from a combination of convective granulation, acoustic oscillations, magnetic activity, and stellar rotation. Much of the short-timescale variability takes the form of ... More
Apsidal Motion of the Massive, Benchmark Eclipsing Binary V578 MonMay 06 2011May 11 2011V578 Mon is a system of two early B-type stars in the Rosette Nebula star-forming region (NGC 2244), and is one of only nine eclipsing binaries with component masses greater than 10 M\odot whose physical parameters have been determined with an accuracy ... More
Detailed Abundances of Planet-Hosting Wide Binaries. II. HD80606 + HD80607Dec 31 2015We present a detailed chemical abundance analysis of 15 elements in the planet-hosting wide binary system HD80606 + HD80607 using Keck/HIRES spectra. As in our previous analysis of the planet-hosting wide binary HD20782 + HD20781, we presume that these ... More
The SLoWPoKES Catalog of Low-mass Ultra-wide Binaries: A Cool Stars Resource for Testing Fundamental Properties and for Constraining Binary Formation TheorySep 11 2012We present results from the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES) catalog of ultra-wide (10^3-10^5.5 AU), low-mass (K5-M7) common proper motion binaries. We constructed a Galactic model, based on empirical stellar number ... More
The High-Order-Multiplicity of Unusually Wide M-dwarf Binaries: Eleven New Triple and Quadruple SystemsJul 21 2010M-dwarfs in extremely wide binary systems are very rare, and may thus have different formation processes from those found as single stars or close binaries in the field. In this paper we search for close companions to a new sample of 36 extremely wide ... More
The Color-Period Diagram and Stellar Rotational Evolution - New Rotation Period Measurements in the Open Cluster M34Mar 26 2011Mar 29 2011We present results from a 5-month photometric survey for stellar rotation periods combined with a 4-year radial-velocity survey for membership and binarity in the 220Myr open cluster M34. We report surface rotation periods for 120 stars, 83 of which are ... More
Solar Flares and Coronal Mass Ejections: A Statistically Determined Flare Flux-CME Mass CorrelationNov 01 2010In an effort to examine the relationship between flare flux and corresponding CME mass, we temporally and spatially correlate all X-ray flares and CMEs in the LASCO and GOES archives from 1996 to 2006. We cross-reference 6,733 CMEs having well-measured ... More
An Empirical Correction for Activity Effects on the Temperatures, Radii, and Estimated Masses of Low-Mass Stars and Brown DwarfsJun 21 2012Jul 17 2012We present empirical relations for determining the amount by which the effective temperatures and radii -- and therefore the estimated masses -- of low-mass stars and brown dwarfs are altered due to chromospheric activity. We base our relations on a large ... More
The Initial Mass Function of the Orion Nebula Cluster across the H-burning limitDec 12 2011We present a new census of the Orion Nebula Cluster (ONC) over a large field of view (>30'x30'), significantly increasing the known population of stellar and substellar cluster members with precisely determined properties. We develop and exploit a technique ... More
A statistical analysis of the accuracy of the digitized magnitudes of photometric plates on the time scale of decades with an application to the century-long light curve of KIC 8462852Jan 27 2016Apr 28 2016We present a statistical analysis of the accuracy of the digitized magnitudes of photometric plates on the time scale of decades. In our examination of archival Johnson B photometry from the Harvard DASCH archive, we find a median RMS scatter of lightcurves ... More
The Stability of F-star Brightness on Century TimescalesMay 09 2016The century-long photometric record of the DASCH project provides a unique window into the variability of stars normally considered to be photometrically inactive. In this paper, we look for long-term trends in the brightness of F stars, with particular ... More
A Strict Test of Stellar Evolution Models: The Absolute Dimensions of Massive Benchmark Eclipsing Binary V578 MonMay 04 2014We determine the absolute dimensions of the eclipsing binary V578 Mon, a detached system of two early B-type stars (B0V + B1V, P$=$2.40848 d) in the star-forming region NGC 2244 of the Rosette Nebula. From the light curve analysis of 40 yr of photometry ... More
Metrics for Optimization of Large Synoptic Survey Telescope Observations of Stellar Variables and TransientsAug 13 2015Aug 17 2015The Large Synoptic Survey Telescope (LSST) will be the largest time-domain photometric survey ever. In order to maximize the LSST science yield for a broad array of transient stellar phenomena, it is necessary to optimize the survey cadence, coverage, ... More
An Improved Determination of the Lithium Depletion Boundary Age of Blanco 1 and a First Look on the Effects of Magnetic ActivitySep 17 2014Sep 23 2014The Lithium Depletion Boundary (LDB) is a robust method for accurately determining the ages of young clusters, but most pre-main-sequence models used to derive LDB ages do not include the effects of magnetic activity on stellar properties. In light of ... More
Constraining Explosion Type of Young Supernova Remnants Using 24 Micron Emission MorphologyJun 14 2013Determination of the explosion type of supernova remnants (SNRs) can be challenging, as SNRs are hundreds to thousands of years old and supernovae (SNe) are classified based on spectral properties days after explosion. Previous studies of thermal X-ray ... More
X-ray Properties of Pre--Main-Sequence Stars in the Orion Nebula Cluster with Known Rotation PeriodsMar 05 2004We re-analyze all archival Chandra/ACIS observations of the Orion Nebula Cluster (ONC) to study the X-ray properties of a large sample of pre--main-sequence (PMS) stars with optically determined rotation periods. Our goal is to elucidate the origins of ... More
Detailed Abundances of Planet-Hosting Wide Binaries. I. Did Planet Formation Imprint Chemical Signatures in the Atmospheres of HD 20782/81?Apr 07 2014Using high-resolution echelle spectra obtained with Magellan/MIKE, we present a chemical abundance analysis of both stars in the planet-hosting wide binary system HD20782 + HD20781. Both stars are G dwarfs, and presumably coeval, forming in the same molecular ... More
SLoWPoKES-II: 100,000 Wide Binaries Identified in SDSS without Proper MotionsApr 20 2015Apr 22 2015We present the SLoWPoKES-II catalog of low-mass visual binaries identified from the Sloan Digital Sky Survey by matching photometric distances. The candidate pairs are vetted by comparing the stellar density at their respective Galactic positions to Monte ... More
Sloan Low-Mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES): A Catalog of Very Wide, Low-mass PairsApr 16 2010We present the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES), a catalog of 1342 very-wide (projected separation >500 AU), low-mass (at least one mid-K--mid-M dwarf component) common proper motion pairs identified from astrometry, ... More
A Simultaneous Optical and X-ray Variability Study of the Orion Nebula Cluster. I. Incidence of Time-Correlated X-ray/Optical VariationsJun 04 2006We present a database of $BVRI$ time-series photometry of the Orion Nebula Cluster obtained with two ground-based telescopes at different longitudes to provide simultaneous coverage with the 13-d Chandra observation of the cluster. The resulting database ... More