A5009641630- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Calibration and Measurement Techniques
- Astronomical Observations and Instrumentation
- Atmospheric chemistry and aerosols
- Spectroscopy and Laser Applications
- Ionosphere and magnetosphere dynamics
- Planetary Science and Exploration
- Advanced Measurement and Metrology Techniques
- Space Exploration and Technology
- Molecular Spectroscopy and Structure
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- History and Developments in Astronomy
- Spacecraft Design and Technology
- Optical Polarization and Ellipsometry
- Advanced optical system design
- Geophysics and Gravity Measurements
- Superconducting and THz Device Technology
- Atmospheric aerosols and clouds
Jet Propulsion Laboratory
2010-2021
California Institute of Technology
2007-2014
Smithsonian Astrophysical Observatory
1995-2013
Columbia University
2009
Johns Hopkins University
2009
Goddard Space Flight Center
2009
Center for Astrophysics Harvard & Smithsonian
1998-2008
Harvard University
1982-2007
University of Miami
2000
Atmospheric and Environmental Research
2000
This report describes the 2014 study by Science Definition Team (SDT) of Wide-Field Infrared Survey Telescope (WFIRST) mission. It is a space observatory that will address most compelling scientific problems in dark energy, exoplanets and general astrophysics using 2.4-m telescope with wide-field infrared instrument an optical coronagraph. The Astro2010 Decadal recommended Wide Field as its top priority for new large As conceived decadal survey, WFIRST would carry out energy science program,...
The major goals of NASA's Terrestrial Planet Finder (TPF) and the European Space Agency's Darwin missions are to detect terrestrial-sized extrasolar planets directly seek spectroscopic evidence habitable conditions life. Here we recommend wavelength ranges spectral features for these missions. We assess known molecular band Earth, Venus, Mars in context putative analogs. preferred 7-25 microns mid-IR 0.5 approximately 1.1 visible near-IR. Detection O2 or its photolytic product O3 merits...
Context. PIONIER stands for Precision Integrated-Optics Near-infrared Imaging ExpeRiment. It combines four 1.8m Auxilliary Telescopes or 8m Unit of the Very Large Telescope Interferometer (ESO, Chile) using an integrated optics combiner. The instrument was at IPAG in December 2009 and commissioned Paranal Observatory October 2010. has provided scientific observations since November
We have developed a characterization of the geological evolution Earths atmosphere and surface in order to model observable spectra an Earth-like planet through its history. These calculations are designed guide interpretation observed spectrum such by future instruments that will characterize exoplanets. Our models focus on spectral features either imply habitability or required for habitability. generated H2O, CO2, CH4, O2, O3, N2O, vegetation-like albedos. chose six epochs characterize....
Several recent designs for planet-finding telescopes use coronagraphs operating at visible wavelengths to suppress starlight along the telescope's optical axis while transmitting any off-axis light from circumstellar material. We describe a class of graded coronagraphic image masks that can, in principle, provide perfect elimination on-axis light, simultaneously maximizing Lyot stop throughput and angular resolution. These "band-limited" operate on intensity plane, not phase. They can work...
High-contrast imaging from space must overcome two major noise sources to successfully detect a terrestrial planet angularly close its parent star: photon diffracted starlight and speckle scattered by instrumentally generated wave front perturbation. Coronagraphs tackle only the contribution reducing at location of planet. Speckle should be addressed with adaptive optics systems. Following tracks Malbet, Yu, Shao, we develop in this paper analytical methods for sensing control that aims...
We have conducted the first systematic study of Herbig Ae/Be stars using technique long baseline stellar interferometry in near-infrared, with objective characterizing distribution and properties circumstellar dust responsible for excess near-infrared fluxes from these systems. The observations this work been at Infrared Optical Telescope Array (IOTA). principal result paper is that interferometer resolves source infrared 11 15 systems surveyed. A new binary, MWC 361-A, has detected...
The Halogen Occultation Experiment (HALOE) experiment is a solar occultation limb sounder which operates between 2.45 and 10.0 μm to measure the composition of mesosphere, stratosphere, upper troposphere. It flies onboard Upper Atmosphere Research Satellite (UARS) was launched in September 1991. Measurements are made transmittance atmosphere number spectral channels as Sun rises or sets behind atmosphere. One channels, at 6.60 μm, broadband filter channel tuned detect absorption ν 2 band...
To characterize the spectrum of Earth viewed as an extrasolar planet, we observed spatially integrated near-infrared (0.7-2.4 μm) reflection via dark side Moon (earthshine). After contributions from Sun, Moon, and local atmosphere were removed, resulting was fitted with a simple model reflectivity Earth. The best fit is dominated by above medium-altitude water clouds, lesser high-altitude ice clouds ground. spectral features seen are H2O (six strong band structures 0.7 to 2.0 μm), CO2...
Small-angle coronagraphy is technically and scientifically appealing because it enables the use of smaller telescopes, allows covering wider wavelength ranges, potentially increases yield completeness circumstellar environment - exoplanets disks detection characterization campaigns. However, opening up this new parameter space challenging. Here we will review four posts high contrast imaging their intricate interactions at very small angles (within first 4 resolution elements from star). The...
Context. It is now generally accepted that the near-infrared excess of Herbig AeBe stars originates in dust a circumstellar disk. Aims. The aims this article are to infer radial and vertical structure these disks at scales order one au, properties grains. Methods. program objects (51 total) were observed with H-band (1.6micron) PIONIER/VLTI interferometer. largest baselines allowed us resolve (at least partially) structures few tenths an au typical distances hundred parsecs. Dedicated...
ABSTRACT Upcoming space-based coronagraphic instruments in the next decade will perform reflected light spectroscopy and photometry of cool directly imaged extrasolar giant planets. We are developing a new atmospheric retrieval methodology to help assess science return inform instrument design for such future missions, ultimately interpret resulting observations. Our technique employs geometric albedo model coupled with both Markov chain Monte Carlo Ensemble Sampler ( emcee ) multimodal...
We report the visible reflection spectrum of integrated Earth, illuminated as it would be seen a spatially unresolved extrasolar planet. The was derived from observation lunar earthshine in range 4800-9200 Å at spectral resolution about 600. observe absorption features ozone, molecular oxygen, and water. see enhanced reflectivity short wavelengths Rayleigh scattering apparently negligible contributions aerosol ocean water scattering. also long starting 7300 Å, corresponding to well-known red...
We report the results of a sensitive K-band survey Herbig Ae/Be disk sizes using 85 m baseline Keck Interferometer. Targets were chosen to span maximum range stellar properties probe size dependence on luminosity and effective temperature. For most targets, measured near-infrared (ranging from 0.2 4 AU) support simple model possessing central optically thin (dust-free) cavity, ringed by hot dust emitting at expected sublimation temperatures (Ts ~1000-1500 K). Furthermore, we find tight...
The ir transmission of the terrestrial atmosphere is calculated at four altitudes interest: Mauna Kea 4.2 km (2-1000 microm), aircraft 14 (5-1000 and balloon 28 41 (10-1000 microm). We show both high resolution spectra (0.05 cm(-1)) broadband averages. results are intended to serve as a detailed guide interference that expected from for astronomical spectroscopy also an indicator relative change in absorption emission can be various observing altitudes. One salient result spectral region...
Using the three-telescope IOTA interferometer on Mount Hopkins, we report results from first near-infrared (λ = 1.65 μm) closure-phase survey of young stellar objects (YSOs). These closure phases allow us to unambiguously detect departures centrosymmetry (i.e., skew) in emission pattern YSO disks scale ~4 mas, expected generic "flared disk" models. Six 14 targets showed small, yet statistically significant nonzero phases, with largest values binary system MWC 361-A and (pre-main-sequence?)...
<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...
Molecular oxygen was detected in martian spectra near 7635 angstroms and its abundance measured both during after the 1971 dust storm. Its column clear atmosphere is about 10.4 +/- 1.0 centimeters amagat, giving a mixing ratio of molecular to carbon dioxide 1.3 x 10-(3). The monoxide (1.4 0.3) quite different from value 0.5 that would result photolysis pure atmosphere, which indicates there or net source relative (probably water) atmosphere.
The Keck Interferometer Nuller (KIN) was used to survey 25 nearby main sequence stars in the mid-infrared, order assess prevalence of warm circumstellar (exozodiacal) dust around solar-type stars. KIN measures emission by spatially blocking star but transmitting flux a region typically 0.1 - 4 AU from star. We find one significant detection (eta Crv), two marginal detections (gamma Oph and alpha Aql), 22 clear non-detections. Using model our own Solar System's zodiacal cloud, scaled...
Although debris discs have been detected around a significant number of main-sequence stars, only few them are known to harbour hot dust in their inner part where terrestrial planets may formed. Thanks infrared interferometric observations, it is possible obtain direct measurement these regions, which prime importance for preparing future exo-Earth characterisation missions. In this context, we resolved the exozodiacal disc Vega with help stellar interferometry and estimated integrated...
Data from Kepler's first 136 days of operation are analyzed to determine the distribution exoplanets with respect radius, period, and host-star spectral type. The analysis is extrapolated estimate percentage terrestrial, habitable-zone exoplanets. Kepler census assumed be complete for bright stars (magnitude <14.0) having transiting planets >0.5 Earth radius periods <42 days. It also that size independent orbital there no hidden biases in data. Six significant statistical results found: a...
We present first results of an experiment to combine data from Keck aperture masking and the Infrared-Optical Telescope Array (IOTA) image circumstellar environments evolved stars with ~20 milliarcsecond resolution. The unique combination excellent Fourier coverage at short baselines high-quality long-baseline fringe allows us determine location clumpiness inner-most hot dust in envelopes, measure diameters underlying themselves. find evidence for large-scale inhomogeneities some shells also...
The Smithsonian far‐infrared spectrometer is a remote sensing Fourier transform that measures the mid‐ and thermal emission spectrum of stratosphere from balloon aircraft platforms. has had nine successful flights 1987 to 1994, flying at float altitudes 36–39 km collecting 131 hours midlatitude stratospheric limb spectra. also flew on NASA DC‐8 aircraft, as part second Airborne Arctic Stratospheric Expedition (AASE‐II), 140 overhead spectra latitudes ranging equator north pole. We present...