A5029571926- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Radio Astronomy Observations and Technology
- Calibration and Measurement Techniques
- Astrophysical Phenomena and Observations
- History and Developments in Astronomy
- Spectroscopy and Laser Applications
- Pulsars and Gravitational Waves Research
- Advanced Measurement and Metrology Techniques
- Scientific Research and Discoveries
- Planetary Science and Exploration
- Advanced Optical Sensing Technologies
- Geophysics and Gravity Measurements
- Historical Astronomy and Related Studies
- Advanced Fiber Optic Sensors
- Non-Invasive Vital Sign Monitoring
- Optical Polarization and Ellipsometry
- Atmospheric Ozone and Climate
- Optical measurement and interference techniques
- Distributed and Parallel Computing Systems
NSF’s NOIRLab
1992-2024
Community Science and Data Center
2020-2024
Kitt Peak National Observatory
2010-2021
Optica
2010-2021
Observatoire de Paris
2003-2020
Laboratoire d’études spatiales et d’instrumentation en astrophysique
2002-2020
Université de Versailles Saint-Quentin-en-Yvelines
2004-2020
Sorbonne Université
2004-2020
Université Paris Cité
2004-2020
Université Paris Sciences et Lettres
2020
We present interferometric diameter measurements of 21 K- and M- dwarfs made with the CHARA Array. This sample is enhanced by literature radii to form a data set 33 K-M diameters measured better than 5%. For all stars, we compute absolute luminosities, linear radii, effective temperatures (Teff). develop empirical relations for \simK0 M4 main- sequence stars between stellar Teff, radius, luminosity broad-band color indices metallicity. These are valid metallicities [Fe/H] = -0.5 +0.1 dex,...
The CHARA Array is a six 1 m telescope optical/IR interferometric array located on Mount Wilson, California, designed and built by the Center for High Angular Resolution Astronomy of Georgia State University. In this paper we describe main elements hardware software control systems, as well data reduction methods currently being used. Our plans upgrades in near future are also described.
Spatially resolving the surfaces of nearby stars promises to advance our knowledge stellar physics. Using optical long-baseline interferometry, we constructed a near-infrared image rapidly rotating hot star Altair with resolution <1 milliarcsecond. The clearly reveals strong effect gravity darkening on highly distorted photosphere. Standard models for uniformly cannot explain findings, which appear result from differential rotation, alternative gravity-darkening laws, or both.
Many high-contrast coronagraph designs have recently been proposed. In this paper, their suitability for direct imaging of extrasolar terrestrial planets is reviewed. We also develop a linear algebra based model coronagraphy that can both explain the behavior existing coronagraphs and quantify coronagraphic performance limit imposed by fundamental physics. find maximum theoretical throughput equal to 1 minus nonaberrated noncoronagraphic PSF telescope. describe how reaching may be designed,...
Based on CHARA Array measurements, we present the angular diameters of 23 nearby, main-sequence stars, ranging from spectral types A7 to K0, 5 which are exoplanet host stars. We derive linear radii, effective temperatures, and absolute luminosities stars using Hipparcos parallaxes measured bolometric fluxes. The new data combined with previously published values create an Angular Diameter Anthology (luminosity classes V IV). This compilation consists 125 diameter uncertainties less than 5%,...
We report on a high angular resolution survey of circumstellar disks around 24 northern sky Be stars. The K-band continuum was made using the CHARA Array long baseline interferometer (baselines 30 to 331 m). interferometric visibilities were corrected for flux contribution stellar companions in those cases where star is member known binary or multiple system. For targets with good uv coverage, we used four parameter Gaussian elliptical disk model fit and determine axial ratio, position...
We present the first resolved images of eclipsing binary β Lyrae, obtained with CHARA Array interferometer and MIRC combiner in H band. The clearly show mass donor thick disk surrounding gainer at all six epochs observation. is brighter generally appears elongated images, direct detection photospheric tidal distortion due to Roche lobe filling. also confirm expectations that component more than relatively fainter this wavelength. Image analysis model fitting for each epoch were used...
We have executed a survey of nearby, main-sequence A-, F-, and G-type stars with the CHARA Array, successfully measuring angular diameters forty-four an average precision ∼1.5%. present new measures bolometric flux, which in turn leads to empirical determination effective temperature for observed. In addition, these CHARA-determined temperatures, radii, luminosities are fit Yonsei–Yale model isochrones constrain masses ages stars. These results compared indirect estimates quantities obtained...
The bright star 55 Cancri is known to host five planets, including a transiting super-Earth. study presented here yields directly determined values for Cnc's stellar astrophysical parameters based on improved interferometry: $R=0.943 \pm 0.010 R_{\odot}$, $T_{\rm EFF} = 5196 24$ K. We use isochrone fitting determine age be 10.2 $\pm$ 2.5 Gyr, implying mass of $0.905 0.015 M_{\odot}$. Our analysis the location and extent system's habitable zone (0.67--1.32 AU) shows that planet f, with period...
We use near-infrared interferometric data coupled with trigonometric parallax values and spectral energy distribution fitting to directly determine stellar radii, effective temperatures luminosities for the exoplanet host stars 61 Vir, ρ CrB, GJ 176, 614, 649, 876, HD 1461, 7924, 33564, 107383 210702. Three of these targets are M dwarfs. Statistical uncertainties in radii range from 0.5 5 per cent 0.2 2 cent, respectively. For eight targets, this work presents first determined radius...
We present direct radii measurements of the well-known transiting exoplanet host stars HD 189733 and 209458 using CHARA Array interferometer. find limb-darkened angular diameters to be theta_LD = 0.3848 +/- 0.0055 0.2254 0.0072 milliarcsec for 209458, respectively. are currently only two systems where detection respective planetary companion's orbital motion from high resolution spectroscopy has revealed absolute masses both star planet. use our new together with information radial velocity...
Near-infrared interferometers have recently imaged a number of rapidly rotating A-type stars, finding levels gravity darkening inconsistent with theoretical expectations. Here, we present new imaging both cooler star β Cas (F2IV) and hotter one α Leo (B7V) using the CHARA array MIRC instrument at H band. Adopting solid-body rotation model simple prescription, modeled stellar geometric properties surface temperature distributions, confirming that stars are show anomalies. We estimate masses...
The late-type dwarf GJ 436 is known to host a transiting Neptune-mass planet in 2.6-day orbit. We present results of our interferometric measurements directly determine the stellar diameter ($R_{\star} = 0.455 \pm 0.018 R_{\odot}$) and effective temperature ($T_{\rm EFF} 3416 54$ K). combine parameters with literature time-series data, which allows us calculate physical orbital system parameters, including 436's mass ($M_{\star} 0.507^{+ 0.071}_{- 0.062} M_{\odot}$) density ($\rho_* 5.37^{+...
Optical and infrared interferometers definitively established that the photometric standard Vega (alpha Lyrae) is a rapidly rotating star viewed nearly pole-on. Recent independent spectroscopic analyses could not reconcile inferred inclination angle with observed line profiles, preferring larger inclination. In order to resolve this controversy, we using six-beam Michigan Infrared Combiner on Center for High Angular Resolution Astronomy Array. With our greater angular resolution dense...
The Large Synoptic Survey Telescope is designed to provide an unprecedented optical imaging dataset that will support investigations of our Solar System, Galaxy and Universe, across half the sky over ten years repeated observation. However, exactly how LSST observations be taken (the observing strategy or "cadence") not yet finalized. In this dynamically-evolving community white paper, we explore detailed performance anticipated science expected depend on small changes strategy. Using...
The unprecedented volume and rate of transient events that will be discovered by the Large Synoptic Survey Telescope (LSST) demands astronomical community update its followup paradigm. Alert-brokers -- automated software system to sift through, characterize, annotate prioritize for critical tools managing alert streams in LSST era. Arizona-NOAO Temporal Analysis Response Events System (ANTARES) is one such broker. In this work, we develop a machine learning pipeline characterize classify...
Vera C. Rubin Observatory is a ground-based astronomical facility under construction, joint project of the National Science Foundation and U.S. Department Energy, designed to conduct multi-purpose 10-year optical survey southern hemisphere sky: Legacy Survey Space Time. Significant flexibility in strategy remains within constraints imposed by core science goals probing dark energy matter, cataloging Solar System, exploring transient sky, mapping Milky Way. The survey's massive data...
We report on K-band interferometric observations of the bright, rapidly rotating star Regulus (type B7 V) made with CHARA Array Mount Wilson, California. Through a combination and spectroscopic measurements, we have determined for equatorial polar diameters temperatures, rotational velocity period, inclination position angle spin axis, gravity darkening coefficient. These first results from provide measurement in represent detection that is not member an eclipsing binary system.
Using two aspheric mirrors, it is possible to apodize a telescope beam without losing light or angular resolution: the output produced by "remapping" entrance produce desired intensity distribution in new pupil. We present phase-induced amplitude apodization coronagraph (PIAAC) concept, which uses this technique, and show that allows efficient direct imaging of extrasolar terrestrial planets with small-sized space. The suitability PIAAC for exoplanet due unique combination achromaticity,...
Interferometrically determined angular diameters for 37 K0-M8 giant and supergiant stars are presented in this paper. It is shown that the effective temperatures sample agree with previous determinations made at CERGA by occultations there no significant difference among temperature scales set three investigations. The data from sources combined to give a new mean relationship between spectral type extending types as late M7, where precision approximately ±95 K each type. question of natural...
<i>Aims. <i/>This paper reports on <i>H<i/>-band interferometric observations of Betelgeuse made at the three-telescope interferometer IOTA. We image and its asymmetries to understand spatial variation photosphere, including diameter, limb darkening, effective temperature, surrounding brightness, bright (or dark) star spots.<i>Methods. <i/>We used different theoretical simulations photosphere dusty environment model visibility data. images with parametric modeling two reconstruction...
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...
We have measured the angular diameters for a sample of 24 exoplanet host stars using Georgia State University's CHARA Array interferometer. use these improved together with Hipparcos parallax measurements to derive linear radii and estimate stars' evolutionary states.
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...
Long-baseline interferometry is an important technique to spatially resolve binary or multiple systems in close orbits. By combining several telescopes together and spectrally dispersing the light, it possible detect faint components around bright stars. Aims. We provide a rigorous detailed method search for high-contrast companions stars, determine detection level, estimate dynamic range from interferometric observations. developed code CANDID (Companion Analysis Non-Detection...