A5042697607- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Space Exploration and Technology
- Planetary Science and Exploration
- Astronomical and nuclear sciences
- High-pressure geophysics and materials
- Adaptive optics and wavefront sensing
- Geophysics and Gravity Measurements
- Spacecraft and Cryogenic Technologies
- Scientific Research and Discoveries
- Particle Accelerators and Free-Electron Lasers
- Astrophysical Phenomena and Observations
- Calibration and Measurement Techniques
- Particle accelerators and beam dynamics
- Solar and Space Plasma Dynamics
- Particle Detector Development and Performance
- History and Developments in Astronomy
- Data Management and Algorithms
- Constraint Satisfaction and Optimization
- Geographic Information Systems Studies
- Atmospheric Ozone and Climate
University of California, Los Angeles
2019-2025
California Institute of Technology
2015-2020
The University of Tokyo
2017
University of Chicago
2017
University of California, Berkeley
2009-2016
Lawrence Berkeley National Laboratory
2007-2014
University of Hawaiʻi at Mānoa
2013
The size of a planet is an observable property directly connected to the physics its formation and evolution. We used precise radius measurements from California-Kepler Survey (CKS) study distribution 2025 $\textit{Kepler}$ planets in fine detail. detect factor $\geq$2 deficit occurrence rate at 1.5-2.0 R$_{\oplus}$. This gap splits population close-in ($P$ < 100 d) small into two regimes: R$_P$ 1.5 R$_{\oplus}$ = 2.0-3.0 R$_{\oplus}$, with few between. Planets these regimes have nearly same...
Significance A major question is whether planets suitable for biochemistry are common or rare in the universe. Small rocky with liquid water enjoy key ingredients biology. We used National Aeronautics and Space Administration Kepler telescope to survey 42,000 Sun-like stars periodic dimmings that occur when a planet crosses front of its host star. found 603 planets, 10 which Earth size orbit habitable zone, where conditions permit surface water. measured detectability these by injecting...
We report on the masses, sizes, and orbits of planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits 7 revealed by precise Doppler measurements host Based an analysis brightness measurements, along with high-resolution imaging spectroscopy, (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all transiting (41 have FPP under 1%), constrain their sizes masses. Most smaller than three...
Abstract The distribution of planet sizes encodes details formation and evolution. We present the most precise size to date based on Gaia parallaxes, Kepler photometry, spectroscopic temperatures from California- Survey. Previously, we measured stellar radii 11% precision using high-resolution spectroscopy; by adding astrometry, errors are now 3%. Planet radius measurements are, in turn, improved 5% precision. With a catalog ∼1000 planets with properties, probed fine detail gap that...
We present astrophysical false positive probability calculations for every Kepler Object of Interest (KOI)---the first large-scale demonstration a fully automated transiting planet validation procedure. Out 7056 KOIs, we determine that 1935 have probabilities <1% to be positives, and thus may considered validated planets. 1284 these not yet been or confirmed by other methods. In addition, identify 428 KOIs likely positives identified as such, though some result unidentified transit timing...
Various theoretical models treating the effect of stellar irradiation on planetary envelopes predict presence a radius valley: i.e. bimodal distribution planet radii, with super-Earths and sub-Neptune planets separated by valley at around $\approx 2~R_\oplus$. Such was observed recently, owing to an improvement in precision stellar, therefore radii. Here we investigate presence, location shape such using small sample highly accurate parameters determined from asteroseismology, which includes...
Probing the connection between a star's metallicity and presence properties of any associated planets offers an observational link conditions during epoch planet formation mature planetary systems. We explore this by analyzing metallicities Kepler target stars subset found to host transiting planets. After correcting for survey incompleteness, we measure occurrence: number per 100 with given $M$. Planet occurrence correlates some, but not all, sizes orbital periods. For warm super-Earths...
We have established precise planet radii, semimajor axes, incident stellar fluxes, and masses for 909 planets in 355 multi-planet systems discovered by Kepler. In this sample, we find that within a single system correlated sizes: each is more likely to be the size of its neighbor than drawn at random from distribution observed sizes. with three or planets, tend regular spacing: orbital period ratios adjacent pairs are correlated. Furthermore, smaller suggesting patterns sizes spacing linked...
We carry out an independent search of Kepler photometry for small transiting planets with sizes 0.5--8.0 times that Earth and orbital periods between 5 50 days, the goal measuring fraction stars harboring such planets. use a new transit algorithm, TERRA, optimized to detect restrict our stellar sample include 12,000 having lowest photometric noise in survey. report 129 planet candidates radii less than 6 Earth-radii found 3 years photometry. Forty-seven these are not Batalha et al. (2012)....
Abstract Classification of stars, by comparing their optical spectra to a few dozen spectral standards, has been workhorse observational astronomy for more than century. Here, we extend this technique compiling library 404 touchstone stars observed with Keck/HIRES the California Planet Search. The have high resolution ( R ≈ 60,000), signal-to-noise ratio (S/N 150/pixel), and are registered onto common wavelength scale. properties derived from interferometry, asteroseismology, LTE synthesis,...
We present a high-precision radial velocity (RV) survey of 719 FGKM stars, which host 164 known exoplanets and 14 newly discovered or revised substellar companions. This catalog updated the orbital parameters long-period candidates, some have decades-longer observational baselines than they did upon initial detection. The range from warm sub-Neptunes super-Earths to cold gas giants. sample selection criteria, as well over 100,000 RV measurements, come Keck-HIRES, APF-Levy, Lick-Hamilton...
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...
Abstract We used high-precision radial velocity measurements of FGKM stars to determine the occurrence giant planets as a function orbital separation spanning 0.03–30 au. Giant are more prevalent at distances 1–10 au compared orbits interior or exterior this range. The increase in planet ∼1 by factor ∼4 is highly statistically significant. A fall-off larger favored over models with flat increasing occurrence. measure <?CDATA ${14.1}_{-1.8}^{+2.0}$?> <mml:math...
Abstract In 2017, the California-Kepler Survey (CKS) published its first data release (DR1) of high-resolution optical spectra 1305 planet hosts. Refined CKS radii revealed that small planets are bifurcated into two distinct populations, super-Earths (smaller than 1.5 R ⊕ ) and sub-Neptunes (between 2.0 4.0 ), with few in between (the “radius gap”). Several theoretical models radius gap predict variation stellar mass, but testing these predictions is challenging DR1 due to limited M ⋆ range...
We search for evidence of a light scalar boson in the radiative decays Upsilon(2S) and Upsilon(3S) resonances: Upsilon(2S,3S)-->gammaA0, A0-->mu+mu-. Such particle appears extensions standard model, where CP-odd Higgs naturally couples strongly to b quarks. find no such processes mass range 0.212 < or = mA0 9.3 GeV samples 99 x 10(6) 122 collected by BABAR detector at SLAC PEP-II B factory set stringent upper limits on effective coupling quark A0. also limit dimuon branching fraction etab...
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 on the discovery and validation of Kepler-452b, a transiting planet identified by search through 4 years data collected NASA's Kepler Mission. This possibly rocky orbits its G2 host star every days, longest orbital period for small ( ) exoplanet to date. The likelihood that this has composition lies between 49% 62%. an effective temperature 5757 ± 85 K 4.32 0.09. At mean separation AU, is well within optimistic habitable zone (recent Venus/early Mars), experiencing only 10% more...
RadVel is an open-source Python package for modeling Keplerian orbits in radial velocity (RV) timeseries. provides a convenient framework to fit RVs using maximum posteriori optimization and compute robust confidence intervals by sampling the posterior probability density via Markov Chain Monte Carlo (MCMC). allows users float or fix parameters, impose priors, perform Bayesian model comparison. We have implemented real-time MCMC convergence tests ensure adequate of posterior. can output...
The California-Kepler Survey (CKS) is an observational program to improve our knowledge of the properties stars found host transiting planets by NASA's Kepler Mission. improvement stems from new high-resolution optical spectra obtained using HIRES at W. M. Keck Observatory. CKS stellar sample comprises 1305 classified as Objects Interest, hosting a total 2075 planets. primary magnitude-limited (Kp < 14.2) and contains 960 with 1385 was extended include some fainter that multiple planets,...
Abstract Exoplanets orbiting pre-main-sequence stars are laboratories for studying planet evolution processes, including atmospheric loss, orbital migration, and radiative cooling. V1298 Tau, a young solar analog with an age of 23 ± 4 Myr, is one such laboratory. The star already known to host Jupiter-sized on 24 day orbit. Here, we report the discovery three additional planets—all between sizes Neptune Saturn—based our analysis K2 Campaign photometry. Planets c d have 5.6 6.4 ,...
We recently used near-infrared spectroscopy to improve the characterization of 76 low-mass stars around which K2 had detected 79 candidate transiting planets. Thirty these worlds were new discoveries that have not previously been published. calculate false positive probabilities transit-like signals are actually caused by non-planetary astrophysical phenomena and reject five events three reported as positives. also statistically validate 18 planets (eight unpublished), confirm earlier...
HD 3167 is a bright (V = 8.9), nearby K0 star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present results of multi-site, multi-instrument radial velocity campaign to characterize system. The masses planets are 5.02+/-0.38 MEarth for b, hot super-Earth with likely rocky composition (rho_b 5.60+2.15-1.43 g/cm^3), and 9.80+1.30-1.24 c, warm sub-Neptune substantial volatile complement (rho_c 1.97+0.94-0.59 g/cm^3). We explore...
Abstract We present stellar and planetary properties for 1305 Kepler Objects of Interest hosting 2025 planet candidates observed as part the California- Survey. combine spectroscopic constraints, presented in Paper I, with interior modeling to estimate masses, radii, ages. Stellar radii are typically constrained 11%, compared 40% when only photometric constraints used. masses 4%, ages 30%. verify integrity parameters through comparisons asteroseismic studies Gaia parallaxes. also recompute...