A5070712011- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Scientific Research and Discoveries
- Advanced Image and Video Retrieval Techniques
- Space Exploration and Technology
- Infrared Target Detection Methodologies
- Remote-Sensing Image Classification
- Atmospheric Ozone and Climate
- Geophysics and Gravity Measurements
- Innovations in Educational Methods
- Atmospheric aerosols and clouds
- Inertial Sensor and Navigation
- Geomagnetism and Paleomagnetism Studies
- Spectroscopy and Laser Applications
- Astronomical and nuclear sciences
- Experimental and Theoretical Physics Studies
- Meteorological Phenomena and Simulations
University of Arizona
2012-2017
University of Cincinnati
2011-2017
Planetary Science Institute
2012-2015
We present results from the "Weather on Other Worlds" Spitzer Exploration Science program to investigate photometric variability in L and T dwarfs, usually attributed patchy clouds. surveyed 44 L3-T8 spanning a range of $J-K_s$ colors surface gravities. find that 14/23 (61%; 95% confidence interval: 41%-78%) our single L3-L9.5 dwarfs are variable with peak-to-peak amplitudes between 0.2% 1.5%, 5/16 (31%; 14%-56%) T0-T8 0.8% 4.6%. After correcting for sensitivity, we 80% (95% 53%-100%) vary...
Beating bands in substellar atmospheres Brown dwarfs are objects with masses that between those of large planets and small stars. They share many features gas giant planets, particularly conditions their atmospheres. Apai et al. analyzed how the infrared brightness three brown changes over time. Several perplexing can be explained if clouds rotating within generate beat patterns. Such seen optical images Jupiter but best match Neptune. The results shed light on atmospheric physics around Sun...
We present $Spitzer$/IRAC Ch1 and Ch2 monitoring of six brown dwarfs during 8 different epochs over the course 20 months. For four dwarfs, we also obtained simulataneous $HST$/WFC3 G141 Grism spectra two derived light curves in five narrow-band filters. Probing pressure levels atmospheres, multi-wavelength our targets all exhibit variations, shape evolves timescale a rotation period, ranging from 1.4 h to 13 h. compare shapes estimate phase shifts between observed at wavelengths by comparing...
Heterogeneous clouds or temperature perturbations in rotating brown dwarfs produce variability the observed flux. We report time-resolved simultaneous observations of variable T6.5 dwarf 2MASSJ22282889-431026 over wavelength ranges 1.1-1.7 microns and broadband 4.5 microns. Spectroscopic were taken with Wide Field Camera 3 on board Hubble Space Telescope photometry Spitzer Telescope. The object shows sinusoidal infrared a period 1.4 hr at most wavelengths peak-to-peak amplitudes between...
Condensate clouds strongly impact the spectra of brown dwarfs and exoplanets. Recent discoveries variable L/T transition argued for patchy in at least some ultracool atmospheres. This study aims to measure frequency level spectral variability search correlations with type. We used HST/WFC3 obtain spectroscopic time series 22 types ranging from L5 T6 1.1-1.7 $\mu$m $\approx$40 min per object. Using Bayesian analysis, we find 6 confident $(p>95\%)$ relative flux one wavelength region...
Precise abundances of 18 elements have been derived for 10 stars known to host giant planets from high signal-to-noise ratio, high-resolution echelle spectroscopy. Internal uncertainties in the are typically ≲ 0.05 dex. The our sample all previously shown that correlate with condensation temperature (Tc) sense increasing Tc; these trends interpreted as evidence may accreted H-depleted planetary material. Our newly also positively Tc, although slopes linear least-square fits [m/H]–Tc...
Photometric monitoring from warm Spitzer reveals that the L3 dwarf DENIS-P J1058.7-1548 varies sinusoidally in brightness with a period of hr and an amplitude 0.388% ± 0.043% (peak-to-valley) 3.6 μm band, confirming reality 4.31 0.31 periodicity detected J-band photometry SOAR telescope. The variations are factor 2.17 0.35 larger than those at μm, while 4.5 observations yield μm/3.6 ratio only 0.23 0.15, consistent zero variability. This wide range amplitudes indicates rotationally modulated...
We present time-resolved near-infrared spectroscopy of two L5 dwarfs, 2MASS J18212815+1414010 and J15074759−1627386, observed with the Wide Field Camera 3 instrument on Hubble Space Telescope (HST). study wavelength dependence rotation-modulated flux variations between 1.1 μm 1.7 μm. find that water absorption bands dwarfs at 1.15 1.4 vary similar amplitudes as adjacent continuum. This differs from results previous HST observations L/T transition in which displays about half amplitude other...
This paper describes an unsupervised machine learning methodology capable of target tracking and background suppression via a novel dual-model approach. ``Jekyll`` produces video bit-mask describing estimate the locations moving objects, ``Hyde`` outputs pseudo-background frame to subtract from original input image sequence. These models were trained with custom-modified version Cross Entropy Loss. Simulated data used compare performance Jekyll Hyde against more traditional supervised...
Abstract In the “Weather on Other Worlds” Spitzer Exploration Science program, we surveyed 44 nearby L3–T8 dwarfs for spot-induced rotational variability. Among single L3–L9.5 dwarfs, found that 80% are variable at >0.2% in 3–5 μm wavelength range, while 36% of T0–T8 were >0.4%. Taking into account viewing angle and sensitivity considerations, both these findings consistent with spots being present ~100% dwarfs. Intriguingly, find a tentative association (92% confidence) between low...