A5041426289- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Solar and Space Plasma Dynamics
- History and Developments in Astronomy
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Digital Games and Media
- Historical Astronomy and Related Studies
- Natural Language Processing Techniques
- Geophysics and Gravity Measurements
- Inertial Sensor and Navigation
- Advanced Algebra and Geometry
- Calibration and Measurement Techniques
- Advanced Computational Techniques and Applications
- Geometric and Algebraic Topology
- Media, Gender, and Advertising
- African history and culture studies
- Cinema and Media Studies
- advanced mathematical theories
- Anomaly Detection Techniques and Applications
Space Telescope Science Institute
2017-2023
California Institute of Technology
2016-2020
City University of New York
2014-2019
Hunter College
2013-2019
American Museum of Natural History
2012-2019
College of Staten Island
2015-2019
U.S. National Science Foundation
2010-2013
Georgia State University
2008-2013
Cerro Tololo Inter-American Observatory
2011
Villanova University
2007
Abstract BANYAN Σ is a new Bayesian algorithm to identify members of young stellar associations within 150 pc the Sun. It includes 27 with ages in range ∼1–800 Myr, modeled multivariate Gaussians six-dimensional (6D) XYZUVW space. first such multi-association classification tool include nearest sub-groups Sco-Cen OB star-forming region, IC 2602, 2391, Pleiades and Platais 8 clusters, ρ Ophiuchi, Corona Australis, Taurus star formation regions. A model field stars built from mixture based on...
We present a new method based on Bayesian analysis to identify members of nearby young kinematic groups. The minimally takes into account the position, proper motion, magnitude, and color star, but other observables can be readily added (e.g., radial velocity, distance). use this find low-mass stars in β Pictoris AB Doradus moving groups TW Hydrae, Tucana-Horologium, Columba, Carina, Argus associations. Starting from sample 758 mid-K mid-M (K5V–M5V) showing youth indicators such as Hα X-ray...
We present the results of a precise near-infrared (NIR) radial velocity (RV) survey 32 low-mass stars with spectral types K2-M4 using CSHELL at NASA IRTF in $K$-band an isotopologue methane gas cell to achieve wavelength calibration and novel iterative RV extraction method. surveyed 14 members young ($\approx$ 25-150 Myr) moving groups, field star $\varepsilon$ Eridani as well 18 nearby ($<$ 25 pc) achieved typical single-measurement precisions 8-15 m s$^{-1}$ long-term stability 15-50...
Abstract We present results of the largest, most comprehensive study ever done stellar multiplicity common stars in Galaxy, red dwarfs. have conducted an all-sky volume-limited survey for companions to 1120 M dwarf primaries known lie within 25 pc Sun via trigonometric parallaxes. In addition a literature search, were explored new surveys at separations 2″–300″. A reconnaissance wide 300″ was blinking archival images. I -band images used search our sample 2″–180″. Various astrometric and...
ABSTRACT We present a kinematic analysis of 152 low surface gravity M7-L8 dwarfs by adding 18 new parallaxes (including 10 for comparative field objects), 38 radial velocities, and 19 proper motions. also add low- or moderate-resolution near-infrared spectra 43 sources confirming their features. Among the full sample, we find 39 objects to be high-likelihood bona fide members nearby moving groups, 92 ambiguous 21 that are non-members. Using this age-calibrated investigate trends in...
We present basic observational data and association membership analysis for 45 young active low-mass stellar systems from the ongoing Research Consortium On Nearby Stars photometry astrometry program at Cerro Tololo Inter-American Observatory. Most of these have saturated X-ray emission (log (LX/Lbol) > −3.5) based on fluxes ROSAT All-Sky Survey, many are significantly more luminous than main-sequence stars comparable color. parallaxes proper motions, Johnson–Kron–Cousins VRI photometry,...
Based on high resolution optical spectra obtained with ESPaDOnS at CFHT, we determine fundamental parameters (\Teff, R, \Lbol, \logg\ and metallicity) for 59 candidate members of nearby young kinematic groups. The candidates were identified through the BANYAN Bayesian inference method \citet{2013malo}, which takes into account position, proper motion, magnitude, color, radial velocity parallax (when available) to establish a membership probability. derived are compared Dartmouth Magnetic...
Context. Though only a handful of extrasolar planets have been discovered via direct imaging, each these discoveries had tremendous impact on our understanding planetary formation, stellar formation and cool atmosphere physics. Aims. Since many newly imaged giant orbit massive A or even B stars we investigated whether could be found orbiting low-mass at large separations. Methods. We conducting an adaptive optic imaging survey to search for planetary-mass companions young M dwarfs the solar...
Abstract We describe the 44 systems discovered to be within 10 pc of Sun by RECONS team, primarily via long-term astrometry program at CTIO/SMARTS 0.9 m that began in 1999. The systems—including 41 with red dwarf primaries, 2 white dwarfs, and 1 brown dwarf—have trigonometric parallaxes greater than 100 mas, errors 0.4–2.4 mas all but one case. provide updated astrometric, photometric ( VRIJHK magnitudes), spectral type, multiplicity information here. Among these are 14 new entries sample,...
We construct a Hertzsprung–Russell diagram for the stellar/substellar boundary based on sample of 63 objects ranging in spectral type from M6V to L4. report newly observed VRI photometry all and new trigonometric parallaxes 37 objects. The remaining 26 have literature. combine our optical with 2MASS WISE employ novel energy distribution fitting algorithm determine effective temperatures, bolometric luminosities, radii. Our uncertainties range ∼20 K ∼150 temperature, ∼0.01 ∼0.06 log (L/L☉)...
HR 8799 is an hF0 mA5 gamma Doradus, lambda Bootis, Vega-type star best known for hosting four directly imaged candidate planetary companions. Using the CHARA Array interferometer, we measure 8799's limb-darkened angular diameter to be 0.342 +/- 0.008 mas; this smallest interferometrically measured stellar date, with error of only 2%. By combining our measurement star's parallax and photometry from literature, greatly improve upon previous estimates its fundamental parameters, including...
GJ 581 is an M dwarf host of a multiplanet system. We use long-baseline interferometric measurements from the CHARA Array, coupled with trigonometric parallax information, to directly determine its physical radius be 0.299 ± 0.010 R☉. Literature photometry data are used perform spectral energy distribution fitting in order 581's effective surface temperature TEFF = 3498 56 K and luminosity L 0.01205 0.00024 L☉. From these measurements, we recompute location extent system's habitable zone...
We present a new nearby young moving group (NYMG) kinematic membership analysis code, LocAting Constituent mEmbers In Nearby Groups (LACEwING), Catalog of Suspected Young Stars, list bona fide members groups, and traceback code. LACEwING is convergence-style algorithm with carefully vetted statistics based on large numerical simulation the Solar Neighborhood. Given spatial information stars, calculates probabilities in 13 NYMGs three open clusters within 100 pc. addition to describing...
We present trigonometric, photometric, and photographic distances to 1748 southern () M dwarf systems with yr−1, of which 1404 are believed lie within 25 pc the Sun. The stars have , covering entire spectral sequence from M0.0 V through M9.5 V. This sample therefore provides a comprehensive snapshot our current knowledge sky for nearest dwarfs that dominate stellar population Galaxy. Roughly one-third systems, each has an primary, published high quality parallaxes, including 179 REsearch...
Astrometric measurements are presented for seven nearby stars with previously detected planets: six M dwarfs (GJ 317, GJ 667C, 581, 849, 876, and 1214) one K dwarf (BD-10 -3166). Measurements also additional without known planets, but which more favorable to astrometric detections of low mass companions, as well three binary systems we provide orbit solutions. Observations have baselines 3 13 years, were made part the RECONS long-term astrometry photometry program at CTIO/SMARTS 0.9 m...
We present trigonometric parallaxes of 64 stellar systems with proper motions between 0\farcs5 yr$^{-1}$ and 1\farcs0 from the ongoing RECONS (Research Consortium On Nearby Stars) parallax program at CTIO (the Cerro Tololo Interamerican Observatory). All are south DEC $= +30$, 58 had no previous parallaxes. In addition to for systems, we motions, Johnson-Kron-Cousins $VRI$ photometry, variability measurements, spectral types. Nine multiple; results their components, three which new...
LP 876-10 is a nearby active M4 dwarf in Aquarius at distance of 7.6 pc. The star new addition to the 10-pc census, with parallax measured via Research Consortium on Nearby Stars (RECONS) astrometric survey Small & Moderate Aperture Telescope System's (SMARTS) 0.9-m telescope. We demonstrate that astrometry, radial velocity, and photometric data for are consistent being third, bound, stellar component Fomalhaut multiple system, despite lying nearly 6 degrees away from A sky. 3D separation...
We present 160 new trigonometric parallaxes for 151 M dwarf systems from the REsearch Consortium On Nearby Stars (RECONS) group's long-term astrometry/photometry program at CTIO/SMARTS 0.9m telescope. Most (124 or 82%) are found to lie within 25 pc. The stars have 119 mas/yr < mu 828 and 3.85 (V-K) 8.47. Among these 58 SuperCOSMOS-RECONS (SCR) search, discovered via our proper motion trawls of SuperCOSMOS digitized archival photographic plates, while remaining were suspected photometric...
We present 41 trigonometric parallaxes of 37 stellar systems, most which have proper motions greater than 1\farcs0 yr$^{-1}$. These are the first for 24 systems. Overall, there 15 red dwarf systems and 22 subdwarf in sample. Five multiples with directly detected companions, we discovered perturbations caused by unseen companions two additional cases, LHS 501 440. The latter system may eventually provide important dynamical mass points on mass-luminosity relation. Two stars note 272, third...
We present the results of a multi-technique investigation M4.5Ve flare star AP Col, which we discover to be nearest pre-main-sequence star. These include astrometric data from CTIO 0.9m, derive proper motion 342.0+/-0.5 mas yr^-1, trigonometric parallax 119.21+/-0.98 (8.39+/-0.07 pc), and photometry photometric variability at optical wavelengths. also provide spectroscopic data, including radial velocity (22.4+/-0.3 km s^-1), lithium Equivalent Width (EW) (0.28+/-0.02 A), H-alpha EW (-6.0...
Abstract As a step toward completing and characterizing the census of solar neighborhood, we present astrometric, photometric, spectroscopic observations 32 systems observed with Cerro Tololo Inter-American Observatory 0.9 m 1.5 telescopes. Astrometry from indicates that among 17 had no previous published trigonometric parallaxes, 14 are within 25 pc. In full sample, nine have proper motions larger than 0.″5 yr −1 , including 2MASS J02511490-0352459, which exceeds 2.″0 . VRI photometry...
We present a radial velocity study of the rapidly rotating B-star Regulus that indicates star is single-lined spectroscopic binary. The orbital period (40.11 d) and probable semimajor axis (0.35 AU) are large enough system not interacting at present. However, mass function suggests secondary has low (M_2 > 0.30 M_sun), we argue companion may be white dwarf. Such would remnant former donor was source spin angular momentum itself.
Abstract We present the first Data Release (DR1) from Hubble Space Telescope (HST) Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) program, a Director’s Discretionary program devoting approximately 1000 HST orbits to production an ultraviolet spectroscopic library young high- and low-mass stars in local universe. The science products this release are combined individual, extracted calibrated spectra obtained with COS STIS instruments aboard HST. Products made using...
We present an analysis of long-term photometric variability for nearby red dwarf stars at optical wavelengths. The sample consists 264 M dwarfs south decl. = +30 with 3.96–9.16 and MV 10–20, corresponding to spectral types M2V–M8V, most which are within 25 pc. have been observed in the VRI filters ∼4–14 yr CTIO/SMARTS 0.9 m telescope. Of 238 pc, we find that only ∼8% photometrically variable by least 20 mmag (∼2%) bands. Only four found vary more than 50 mmag, including GJ 1207 8.6...
ABSTRACT We use 612 single stars with previously published trigonometric parallaxes placing them within 25 pc to evaluate released in Gaia ’ s first data release (DR1). find that the are, on average, 0.24 ± 0.02 mas smaller than weighted mean parallax values for these solar neighborhood. also offset changes distance out 100 pc, sense closer star, larger offset. no systematic trends offsets stellar V magnitude, − K color, or proper motion. do is roughly twice as large south of ecliptic...