A5053193729- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Material Science and Thermodynamics
- Pigment Synthesis and Properties
- Chemical and Physical Properties in Aqueous Solutions
- Law, logistics, and international trade
- Statistical and numerical algorithms
- GNSS positioning and interference
- Geophysics and Gravity Measurements
- Rangeland Management and Livestock Ecology
- Nuclear physics research studies
- Oil Palm Production and Sustainability
- Astrophysical Phenomena and Observations
- Pacific and Southeast Asian Studies
- Spacecraft Design and Technology
- Plant Ecology and Taxonomy Studies
- Maritime and Coastal Archaeology
- Molecular Spectroscopy and Structure
- Constraint Satisfaction and Optimization
University of Hawaiʻi at Mānoa
2013-2024
University of Hawaii System
2010-2023
Woodlawn School
2015
University of California, Berkeley
2010
Correlations between stellar properties and the occurrence rate of exoplanets can be used to inform target selection future planet-search efforts provide valuable clues about planet-formation process. We analyze a sample 1266 stars drawn from California Planet Survey targets determine empirical functional form describing likelihood star harboring giant planet as function its mass metallicity. Our ranges M dwarfs with masses low 0.2 M⊙ intermediate-mass subgiants high 1.9 M⊙. In agreement...
We have used Pan-STARRS1 to discover an extremely red late-L dwarf, which has (J-K)_MKO = 2.84 and (J-K)_2MASS 2.78, making it the reddest known field dwarf second only 2MASS J1207-39b among substellar companions. Near-IR spectroscopy shows a spectral type of L7 reveals triangular H-band continuum weak alkali (K I Na I) lines, hallmarks low surface gravity. astrometry from Hawaii Infrared Parallax Program gives distance 24.6+/-1.4 pc indicates much fainter J-band absolute magnitude than L...
We present 197 planet candidates discovered using data from the first year of NASA K2 mission (Campaigns 0-4), along with results an intensive program photometric analyses, stellar spectroscopy, high-resolution imaging, and statistical validation. distill these into sets 104 validated planets (57 in multi-planet systems), 30 false positives, 63 remaining candidates. Our systems span a range properties, median values R_P = 2.3 R_E, P=8.6 d, Tef 5300 K, Kp=12.7 mag. Stellar spectroscopy...
Small, cool planets represent the typical end-products of planetary formation. Studying architectures these systems, measuring planet masses and radii, observing planets' atmospheres during transit directly informs theories assembly, migration, evolution. Here we report discovery three small orbiting a bright (Ks = 8.6 mag) M0 dwarf using data collected as part K2, new ecliptic survey re-purposed Kepler spacecraft. Stellar spectroscopy K2 photometry indicate that system hosts transiting with...
We report the discovery of 76 new T dwarfs from UKIDSS Large Area Survey (LAS). Near-infrared broad and narrow-band photometry spectroscopy are presented for objects, along with WISE warm-Spitzer photometry. Proper motions 128 a two epoch LAS proper motion catalogue. use these to identify benchmark systems: LHS 6176AB, T8+M4 pair HD118865AB, T5.5+F8 pair. Using age constraints primaries evolutionary models constrain radii we have estimated their physical properties bolometric luminosity....
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...
We present the discovery of 57 wide (>5'') separation, low-mass (stellar and substellar) companions to stars in solar neighborhood identified from Pan-STARRS 1 (PS1) data spectral classification 31 previously known companions. Our represent a selective subsample promising candidates span range type K7–L9 with addition one DA white dwarf. These were primarily dedicated common proper motion search around nearby stars, along few as serendipitous discoveries our brown dwarf search. include 23...
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...
We present a catalog of 11 multi-planet systems from Campaigns 1 and 2 the K2 mission. report sizes orbits 26 planets split between seven 2-planet four 3-planet systems. These stem systematic search photometry for all dwarf stars observed by in these fields. precisely characterized host with adaptive optics imaging analysis high-resolution optical spectra Keck/HIRES medium-resolution IRTF/SpeX. confirm two planet candidates mass detection validate remaining 24 to $>99\%$ confidence. Thirteen...
Open clusters have been the focus of several exoplanet surveys but only a few planets so far discovered. The \emph{Kepler} spacecraft revealed an abundance small around small, cool stars, therefore, such cluster members are prime targets for transit searches. Kepler's new mission, K2, is targeting open and star-forming regions ecliptic to search transiting their low-mass constituents. Here, we report discovery first planet in intermediate-age (800 Myr) Beehive (Praesepe). K2-95 faint...
We present 0.95–1.80 μm spectroscopy of the ∼12–27 MJup companion orbiting faint (R ∼ 13.6), young (∼120 Myr) M-dwarf 2MASS J01225093–2439505 ("2M0122–2439 B") at 1 5 separation (50 AU). Our coronagraphic long-slit was obtained with new high contrast imaging platform Very Large Telescope Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) during Science Verification. The unique capability SPHERE enables spectral resolution an order magnitude higher than other extreme AO exoplanet...
ABSTRACT The prime Kepler mission revealed that small planets (<4 <?CDATA ${R}_{\oplus }$?> <?MML <mml:math> <mml:msub> <mml:mrow> <mml:mi>R</mml:mi> </mml:mrow> <mml:mo>⊕</mml:mo> </mml:msub> </mml:math>?> ) are common, especially around low-mass M dwarfs. K 2, the repurposed mission, continues this exploration of stars. Here we combine 2 photometry with spectroscopy, adaptive optics imaging, and archival survey images to analyze two orbiting nearby field-age dwarfs, K2-26 (EPIC...
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...
We report the discovery of an unusually red brown dwarf found in a search for high proper motion objects using WISE and 2MASS data. WISEP J004701.06+680352.1 is moving at 044 yr−1 lies relatively close to Galactic plane (b = 52). Near-infrared photometry spectroscopy reveals that this one reddest (2MASS J − Ks 2.55 ± 0.08 mag) field L dwarfs yet detected, making object important member class dwarfs. discuss evidence thick condensate clouds speculate on age object. Although models by...
Metallicity is a fundamental parameter that contributes to the physical characteristics of star. The low temperatures and complex molecules present in M dwarf atmospheres make it difficult measure their metallicities using techniques have been commonly used for Sun-like stars. Although there has significant progress developing empirical methods over last few years, these developed primarily early- mid-M dwarfs. We method metallicity mid- late-M dwarfs from moderate resolution (R ∼ 2000)...
We have combined optical and NIR photometry from Pan-STARRS 1 UKIDSS to search the young (5-10 Myr) star-forming region of Upper Scorpius for wide (~400-4000 AU) substellar companions down ~5 Mjup. Our is ~4mag deeper than previous work based on 2MASS. identified several candidates around known stellar members using a combination color selection spectral energy distribution fitting. followup spectroscopy has two new as well confirmed previously photometry, with types M7.5-M9 masses ~15-60...
The evolution of brown dwarfs from L to T spectral types is one the least understood aspects ultracool population, partly for lack a large, well-defined, and well-characterized sample in L/T transition. To improve existing census, we have searched $\approx$28,000 deg$^2$ using Pan-STARRS1 WISE surveys transition within 25 pc. We present 130 dwarf discoveries with estimated distances $\approx9-130$ pc, including 21 that were independently discovered by other authors 3 previously identified as...
We present novel tests of pre-main-sequence models based on individual dynamical masses for the M7 binary LSPM J1314+1320AB. Joint analysis Keck adaptive optics astrometric monitoring along with Very Long Baseline Array radio data from a companion paper yield component 92.8 ± 0.6 MJup (0.0885 0.0006 M☉) and 91.7 1.0 (0.0875 0.0010 parallactic distance 17.249 0.013 pc. find luminosities consistent system being coeval at 80.8 2.5 Myr, according to BHAC15 evolutionary models. The presence...
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...
Substellar members of young ($\lesssim$150 Myr) moving groups are valuable benchmarks to empirically define brown dwarf evolution with age and study the low-mass end initial mass function. We have combined Pan-STARRS1 (PS1) proper motions optical$-$IR photometry from PS1, 2MASS $\textit{WISE}$ search for substellar AB Dor Moving Group within $\approx$50 pc spectral types late-M early-L, corresponding masses down $\approx$30 M$_{Jup}$ at group ($\approx$125 Myr). Including both allows us...
We have searched ~8200 sq. degs for high proper motion (~0.5-2.7"/year) T dwarfs by combining first-epoch data from the Pan-STARRS1 (PS1) 3-Pi Survey, 2MASS All-Sky Point Source Catalog, and WISE Preliminary Data Release. identified two objects with very red (W1-W2) colors characteristic of dwarfs, one being known T7.5 dwarf GJ 570D. Near-IR spectroscopy other object (PSO J043.5+02 = WISEP J0254+0223) reveals a spectral type T8, leading to photometric distance 7.2+/-0.7 pc. The 2.56"/yr PSO...
We present optical and near-infrared adaptive optics (AO) imaging spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7–M4.5), most which have recently been identified as candidate members nearby young moving groups (YMGs; 8–120 Myr) in the literature. Three these are new our AO survey, two others confirmed be comoving with their host for first time. The inferred masses (∼10–100 MJup) highly sensitive ages primary stars; therefore we critically examine kinematic spectroscopic...
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...
The NASA K2 mission uses photometry to find planets transiting stars of various types. M dwarfs are high interest since they host more short period than any other type main sequence and around have deeper transits compared stars. In this paper, we present stellar parameters from K hosting planet candidates discovered by our team. Using the SOFI spectrograph on European Southern Observatory's New Technology Telescope, obtained R ~ 1000 J-, H-, K-band (0.95 - 2.52 microns) spectra 34 late-type...
We present initial results from a wide-field (30,000 deg2) search for L/T transition brown dwarfs within 25 pc using the Pan-STARRS1 and Wide-field Infrared Survey Explorer (WISE) surveys. Previous large-area searches have been incomplete dwarfs, because these objects are faint in optical bands near-infrared (near-IR) colors that difficult to distinguish background stars. To overcome obstacles, we cross-matched (optical) WISE (mid-IR) catalogs produce unique multi-wavelength database finding...