A5070886037- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Atmospheric Ozone and Climate
- Astronomical Observations and Instrumentation
- Spectroscopy and Laser Applications
- Chemical and Physical Properties in Aqueous Solutions
- Pigment Synthesis and Properties
- Solar and Space Plasma Dynamics
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Calibration and Measurement Techniques
- Zeolite Catalysis and Synthesis
- Catalysis and Oxidation Reactions
- Optical and Acousto-Optic Technologies
- Ionosphere and magnetosphere dynamics
- Geophysics and Gravity Measurements
- Space Exploration and Technology
- High-pressure geophysics and materials
- Geological and Geophysical Studies
- Infrared Target Detection Methodologies
- Spectroscopy and Chemometric Analyses
The University of Texas at Austin
2022-2024
University of California, Santa Cruz
2023-2024
Nanjing University
2016-2024
University of Hawaiʻi at Mānoa
2018-2023
University of Hawaii System
2017-2022
National Aeronautics and Space Administration
2022
This paper defines the UK Infra-Red Telescope (UKIRT) Hemisphere Survey (UHS) and release of remaining ~12,700 sq.deg J-band survey data products. The UHS will provide continuous J K-band coverage in northern hemisphere from a declination 0 deg to 60 by combining existing Large Area Survey, Galactic Plane Clusters conducted under UKIRT Infra-red Deep Sky (UKIDSS) programme with this new additional area not covered UKIDSS. released includes imaging source catalogues over area, which, together...
We present a catalog of 9888 M, L and T dwarfs detected in the Pan-STARRS1 3$\pi$ Survey (PS1), covering three-quarters sky. Our contains nearly all known objects spectral types L0-T2 PS1 field, with as early M0 late T9, includes PS1, 2MASS, AllWISE, Gaia DR1 photometry. analyze different photometry reported by use two our to maximize both depth accuracy. Using parallaxes from literature, we construct empirical SEDs for field ultracool spanning 0.5-12 $\mu$m. determine typical colors M0-T9...
Benchmark brown dwarf companions with well-determined ages and model-independent masses are powerful tools to test substellar evolutionary models probe the formation of giant planets dwarfs. Here, we report independent discovery HIP~21152~B, first imaged companion in Hyades, conduct a comprehensive orbital atmospheric characterization system. HIP~21152 was targeted an ongoing high-contrast imaging campaign stars exhibiting proper motion changes between Hipparcos Gaia, also recently...
Abstract The orientation between a star’s spin axis and planet’s orbital plane provides valuable information about the system’s formation dynamical history. For non-transiting planets at wide separations, true stellar obliquities are challenging to measure, but lower limits on spin–orbit orientations can be determined from difference inclination of rotational companion’s (Δ i ). We present results uniform analysis rotation periods, inclinations, cool stars (SpT ≳ F5) hosting directly imaged...
Abstract We derive the bolometric luminosities ( L bol ) of 865 field-age and 189 young ultracool dwarfs (spectral types M6–T9, including 40 new discoveries presented here) by directly integrating flux-calibrated optical to mid-infrared (MIR) spectral energy distributions (SEDs). The SEDs consist low-resolution R ∼ 150) near-infrared (NIR; 0.8–2.5 μ m) spectra (including for 97 objects), photometry from Pan-STARRS1 survey, MIR CatWISE2020 survey Spitzer/IRAC. Our calculations benefit recent...
Abstract AF Lep A+b is a remarkable planetary system hosting gas-giant planet that has the lowest dynamical mass among directly imaged exoplanets. We present an in-depth analysis of atmospheric composition star and to probe planet’s formation pathway. Based on new high-resolution spectroscopy A, we measure uniform set stellar parameters elemental abundances (e.g., [Fe/H] = −0.27 ± 0.31 dex). The ( <?CDATA ${2.8}_{-0.5}^{+0.6}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Abstract Atmospheric escape shapes the fate of exoplanets, with statistical evidence for transformative mass loss imprinted across mass–radius–insolation distribution. Here, we present transit spectroscopy highly irradiated, low-gravity, inflated hot Saturn HAT-P-67 b. The Habitable Zone Planet Finder spectra show a detection up to 10% absorption depth 10833 Å helium triplet. 13.8 hr on-sky integration time over 39 nights sample entire planet orbit, uncovering excess preceding by 130...
Capturing planets in the act of losing their atmospheres provides rare opportunities to probe evolution history. This analysis has been enabled by observations helium triplet at 10,833 angstrom, but past studies have focused on narrow time window right around planet’s optical transit. We monitored hot Jupiter HAT-P-32 b using high-resolution spectroscopy from Hobby-Eberly Telescope covering full orbit. detected escaping a 14σ significance,with extended leading and trailing tails spanning...
The study of distant galaxy groups and clusters at the peak epoch star formation is limited by lack a statistically homogeneously selected spectroscopically confirmed sample. Recent discoveries concentrated starburst activities in cluster cores have opened new window to hunt for these structures based on their integrated IR luminosities. Here, we carry out large NOEMA (NOrthern Extended Millimeter Array) program targeting statistical sample infrared-luminous sources associated with...
We present a search for new planetary-mass members of nearby young moving groups (YMGs) using astrometry 694 T and Y dwarfs, including 447 objects with parallaxes, mostly produced by recent large parallax programs from UKIRT Spitzer. Using the BANYAN $\Sigma$ LACEwING algorithms, we identify 30 candidate YMG members, spectral types T0$-$T9 distances $10-43$ pc. Some candidates have unusually red colors and/or faint absolute magnitudes compared to field dwarfs similar types, providing...
Abstract Giant planets grow by accreting gas through circumplanetary disks, but little is known about the timescale and mechanisms involved in planet-assembly process because few protoplanets have been discovered. Recent visible infrared imaging revealed a potential protoplanet within transition disk around young intermediate-mass Herbig Ae star, AB Aurigae (AB Aur). Additional H α probed for accretion found agreement between line-to-continuum flux ratio of star companion, raising...
Abstract We present a uniform forward-modeling analysis of 90 late-M and L dwarfs in nearby young (∼10–200 Myr) moving groups, the Pleiades, Hyades using low-resolution ( R ≈ 150) near-infrared (0.9–2.4 μ m) spectra BT-Settl model atmospheres. derive objects’ effective temperatures, surface gravities, radii, masses by comparing our to models Bayesian framework with nested sampling calculate same parameters evolutionary models. Assuming evolutionary-based are more robust, spectroscopically...
Abstract We are conducting a proper-motion survey for young brown dwarfs in the Taurus-Auriga molecular cloud based on Pan-STARRS1 3 π Survey. Our search uses multi-band photometry and astrometry to select candidates, is wider (370 deg 2 ) deeper (down ≈3 M Jup than previous searches. present here our methods spectroscopic follow-up of high-priority candidates. Since extinction complicates spectral classification, we have developed new approach using low-resolution ( R ≈ 100) near-infrared...
The relation between star formation rates and stellar masses, i.e. the galaxy main sequence, is a useful diagnostic of evolution. We present distributions relative to sequence 55 optically-selected PG 12 near-IR-selected 2MASS quasars at z <= 0.5. estimate quasar host masses from Hubble Space Telescope or ground-based AO photometry, through mid-infrared aromatic features far-IR photometry. find that hosts more less follow defined by normal star-forming galaxies while lie systematically above...
We present the identification of COCONUTS-2 system, composed M3 dwarf L 34-26 and T9 WISEPA J075108.79$-$763449.6. Given their common proper motions parallaxes, these two field objects constitute a physically bound pair with projected separation 594$"$ (6471 au). The primary star COCONUTS-2A has strong stellar activity (H$\alpha$, X-ray, UV emission) is rapidly rotating ($P_{\rm rot} = 2.83$ days), from which we estimate an age 150-800 Myr. Comparing equatorial rotational velocity derived...
Abstract Measurements of the C/O ratio in brown dwarfs are lacking, part due to past models adopting solar only. We have expanded ATMO 2020 atmosphere model grid include nonsolar metallicities and ratios T dwarf regime. change by altering either carbon or oxygen elemental abundances, we find that abundances these elements can be distinguished based on shapes H K bands. compare new with medium-resolution ( R ≈ 1700), near-infrared (0.8–2.4 μ m) Gemini Near-Infrared Spectrograph (GNIRS)...
Magnetospheric processes seen in gas-giants such as aurorae and circularly-polarized cyclotron maser radio emission have been detected from some brown dwarfs. However, previous observations targeted known dwarfs discovered via their infrared emission. Here we report the discovery of BDR J1750+3809, a circularly polarized source around 144 MHz with LOFAR telescope. Follow-up near-infrared photometry spectroscopy show that J1750+3809 is cold methane dwarf spectral type T$6.5\pm 1$ at distance...
We present a large forward-modeling analysis for 55 late-T (T7-T9) dwarfs, using low-resolution ($R\approx150$) near-infrared spectra and cloudless Sonora-Bobcat model atmospheres. derive the objects' effective temperatures, surface gravities, metallicities, radii, masses, luminosities our newly developed Bayesian framework, use resulting population properties to test find (1) fitted metallicities are 0.3-0.4 dex lower than those of nearby stars; (2) their ages derived from spectroscopic...
The spectra of brown dwarfs are key to exploring the chemistry and physics that take place in their atmospheres. Late-T dwarf particularly diagnostic due relatively cloud-free atmospheres deep molecular bands. With use powerful atmospheric retrieval tools applied these objects, direct constraints on molecular/atomic abundances, gravity, vertical thermal profiles can be obtained enabling a broad exploration chemical/physical mechanisms operating We present uniform analysis low-resolution IRTF...
Recent observations of planetary atmospheres in HAT-P-32 b and HAT-P-67 reveal extensive outflows reaching up to hundreds radii. The helium 1083 nm light curves for these planets, captured across their full orbits, show notable asymmetries: both planets display more pronounced pre-transit than post-transit absorptions, with being the extreme case. Using 3D hydrodynamic simulations, we identified key factors influencing formation a dense leading outflow stream characterized its morphology....
Abstract We present the discovery of eight young M7–L2 dwarfs in Taurus star-forming region and Scorpius–Centaurus OB Association, serendipitously found during a wide-field search for L/T transition using Pan-STARRS1 (optical) WISE (mid-infrared) photometry. identify PSO J060.3200+25.9644 (near-infrared spectral type L1) J077.1033+24.3809 (L2) as new members based on their vl-g gravity classifications, consistency photometry proper motions with previously known objects, low probability...
We present a forward-modeling framework using the Bayesian inference tool Starfish and cloudless Sonora-Bobcat model atmospheres to analyze low-resolution ($R\approx80-250$) near-infrared ($1.0-2.5$ $\mu$m) spectra of T dwarfs. Our approach infers effective temperatures, surface gravities, metallicities, radii, masses, by accounting for uncertainties from interpolation correlated residuals due instrumental effects modeling systematics, produces more realistic parameter posteriors than...
We present the latest and most precise characterization of architecture for ancient ($\approx 11$ Gyr) Kepler-444 system, which is composed a K0 primary star (Kepler-444 A) hosting five transiting planets, tight M-type spectroscopic binary BC) with an A-BC projected separation 66 au. have measured system's relative astrometry using adaptive optics imaging from Keck/NIRC2 A's radial velocities Hobby Eberly Telescope, re-analyzed between BC A Keck/HIRES. also include Hipparcos-Gaia astrometric...
Abstract AF Lep b is a rare directly imaged exoplanet with properties consistent core-accretion evolution models. Using its precise dynamical mass and spectroscopically inferred bolometric luminosity alongside the Spiegel & Burrows models, I determined an initial entropy >8.7 k B /baryon at 3 σ age of 12 ± 4 Myr for b. Comparing this planet’s to isochrone (24 Myr) host association, β Pictoris moving group (BPMG), suggests formed 5 later than star. Alternatively, BPMG’s updated...