A5012593967- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Atmospheric Ozone and Climate
- Astrophysics and Star Formation Studies
- Structural Health Monitoring Techniques
- Isotope Analysis in Ecology
- Spectroscopy and Laser Applications
- Cosmology and Gravitation Theories
- Visual perception and processing mechanisms
- Meteorological Phenomena and Simulations
- Geophysics and Gravity Measurements
- Space Exploration and Technology
- Korean Peninsula Historical and Political Studies
- Tactile and Sensory Interactions
- Aeroelasticity and Vibration Control
- Insect and Arachnid Ecology and Behavior
- Chemical Thermodynamics and Molecular Structure
- Solar and Space Plasma Dynamics
- Structural Engineering and Vibration Analysis
- Structural Response to Dynamic Loads
- Physiological and biochemical adaptations
- Japanese History and Culture
- Calibration and Measurement Techniques
- Balance, Gait, and Falls Prevention
Massachusetts Institute of Technology
1995-2024
IIT@MIT
2021
Old Dominion University
1986-2007
Chinese University of Hong Kong
2003
Center for Cancer Research
1995
Abstract Clouds are prevalent in many of the exoplanet atmospheres that have been observed to date. For transiting exoplanets, we know if clouds present because they mute spectral features and cause wavelength-dependent scattering. While exact composition these is largely unknown, this information vital understanding chemistry energy budget planetary atmospheres. In work, observe one transit hot Jupiter WASP-17b with JWST’s Mid-Infrared Instrument Low Resolution Spectrometer generate a...
Abstract We present the first emission spectrum of hot Jupiter WASP-17 b using one eclipse observation from JWST Near Infrared Imager and Slitless Spectrograph (NIRISS) Single Object Spectroscopy (SOSS) mode. Covering a wavelength range 0.6–2.8 μ m, our retrieval analysis reveals strong detection H 2 O in b’s dayside atmosphere (6.4 σ ). Our retrievals consistently favor supersolar abundance noninverted temperature–pressure profile over large pressure range. Additionally, examination...
Abstract The JWST NIRSpec integral field unit (IFU) presents a unique opportunity to observe directly imaged exoplanets from 3 5 μ m at moderate spectral resolution ( R ∼ 2700) and thereby better constrain the composition, disequilibrium chemistry, cloud properties of their atmospheres. In this work, we present first IFU high-contrast observations substellar companion that requires starlight suppression techniques. We develop specific data-reduction strategies study faint companions around...
Ammonia (NH3) in a terrestrial planet atmosphere is generally good biosignature gas, primarily because planets have no significant known abiotic NH3 source. The conditions required for to accumulate the are, however, stringent. NH3's high water solubility and bio-useability likely prevent from accumulating detectable levels unless life net source of produces enough saturate surface sinks. Only then can with reasonable production flux. For highly favorable planetary scenario H2-dominated...
Abstract We develop and disseminate effective point-spread functions geometric-distortion solutions for high-precision astrometry photometry with the JWST NIRISS instrument. correct field dependencies detector effects, assess quality temporal stability of calibrations. As a scientific application validation, we study proper motion (PM) kinematics stars in calibration near Large Magellanic Cloud (LMC) center, comparing to first-epoch Hubble Space Telescope (HST) archival catalog 16 yr...
Abstract About 2.5 billion years ago, microbes learned to harness plentiful solar energy reduce CO 2 with H O, extracting and producing O as waste. production from this metabolic process was so vigorous that it saturated its photochemical sinks, permitting reach “runaway” conditions rapidly accumulate in the atmosphere despite reactivity. Here we argue may not be unique: diverse gases produced by life experience a effect similar . This runaway occurs because ability of an photochemically...
Abstract Water has proven to be ubiquitously detected in near-infrared (NIR) transmission spectroscopy observations of hot Jupiter atmospheres, including WASP-17b. However, previous analyses WASP-17b’s atmosphere based upon Hubble Space Telescope (HST) and Spitzer data could not constrain the water abundance, finding that subsolar, supersolar, bimodal posterior distributions were all statistically valid. In this work, we observe one transit WASP-17b using JWST’s Near Infrared Imager Slitless...
Abstract We present the first spectroscopic characterization of dayside atmosphere WASP-17b in mid-infrared using a single JWST MIRI/LRS eclipse observation. From forward-model fits to 5–12 μ m emission spectrum, we tightly constrain heat redistribution factor be 0.92 ± 0.02 at pressures probed by this data, indicative inefficient global redistribution. also marginally detect supersolar abundance water, consistent with previous findings for WASP-17b, but note our weak constraints on...
In a piezo-based self-sensing actuation (SSA) configuration, the control signal is mixed with due to mechanical response. The success of SSA relies on extraction that response from signal. Owing relatively high amplitudes those two signals and ambience varying property equivalent capacitance piezoelectric element, fix designed bridge circuit in configuration would extract corrupted under variation capacitance. This degrade system performance or even destabilize closed loop system. this...
Abstract Waste gas products from technological civilizations may accumulate in an exoplanet atmosphere to detectable levels. We propose nitrogen trifluoride (NF 3 ) and sulfur hexafluoride (SF 6 as ideal technosignature gases. Earth life avoids producing or using any N–F S–F bond-containing molecules makes no fully fluorinated with element. NF SF be universal technosignatures owing their special industrial properties, which unlike biosignature gases, are not species-dependent. Other key...
Abstract Biosignature gas research has been growing in recent years thanks to next-generation space- and ground-based telescopes. Methanol (CH 3 OH) many advantages as a biosignature candidate. First, CH OH’s hydroxyl group (OH) unique spectral feature not present other anticipated gases the atmospheres of rocky exoplanets. Second, there are no significant known abiotic OH sources on terrestrial planets solar system. Third, life Earth produces large quantities. However, despite advantages,...
The search for possible biosignature gases in habitable exoplanet atmospheres is accelerating, although actual observations are likely years away. This work adds isoprene, C5H8, to the roster of gases. We found that isoprene geochemical formation highly thermodynamically disfavored and has no known abiotic false positives. production rate on Earth rivals methane (CH4; ∼500 Tg/year). Unlike methane, rapidly destroyed by oxygen-containing radicals. Although predominantly produced deciduous...
We used VLT/SPHERE to observe 20 systems in the Cha I cloud polarized scattered light near-infrared. combined observations with existing literature data on stellar properties and archival ALMA continuum study trends system age dust mass. also connected resolved near-infrared spectral energy distributions of systems. In 13 included this we detected signals from circumstellar dust. For CR Cha, CT CV SY SZ VZ present first detailed descriptions disks light. The found typically smooth or faint...
Abstract The search for signs of life beyond Earth is a crucial driving motivation exoplanet science, fueling new work on biosignature gases in habitable atmospheres. We study carbonyls, category molecules containing the C=O double bond, following our proposal to systematically identify plausible gas candidates from list all small volatile molecules. rule out carbonyls as due both their high water solubility and photolysis rate, despite ubiquitous production by Earth, critical importance...
Abstract The search for signs of life on other worlds has largely focused terrestrial planets. Recent work, however, argues that could exist in the atmospheres temperate sub-Neptunes. Here we evaluate usefulness carbon dioxide isotopologues as evidence aerial life. Carbon isotopes are particular interest, metabolic processes preferentially use lighter 12 C over 13 C. In principle, upcoming James Webb Space Telescope (JWST) will be able to spectrally resolve and CO 2 , but not CH 4 . We...
The JWST NIRSpec integral field unit (IFU) presents a unique opportunity to observe directly imaged exoplanets from 3-5um at moderate spectral resolution (R~2,700) and thereby better constrain the composition, disequilibrium chemistry, cloud properties of their atmospheres. In this work, we present first IFU high-contrast observations substellar companion that requires starlight suppression techniques. We develop specific data reduction strategies study faint companions around bright stars,...
Hardware elements have been studied in terms of their applicability to Mars oxygen production systems. Various aspects the system design are discussed and areas requiring further research identified. Initial work on reliability is a methodology for applying expert technology processor described.
Water has proven to be ubiquitously detected in near-infrared (NIR) transmission spectroscopy observations of hot Jupiter atmospheres, including WASP-17b. However, previous analyses WASP-17b's atmosphere based upon Hubble Space Telescope (HST) and Spitzer data could not constrain the water abundance, finding that sub-solar, super-solar bimodal posterior distributions were all statistically valid. In this work, we observe one transit WASP-17b using JWST's Near Infrared Imager Slitless...
Exoplanet atmospheres are expected to vary significantly in thickness and chemical composition, leading a continuum of differences surface pressure atmospheric density. This variability is exemplified within our Solar System, where the four rocky planets exhibit pressures ranging from 1 nPa on Mercury 9.2 MPa Venus. The direct effects potential challenges density life have rarely been discussed. For instance, directly affects possibility active flight organisms, critical factor since without...