Rachel Akeson
A5057911498- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Molecular Spectroscopy and Structure
- Calibration and Measurement Techniques
- Gamma-ray bursts and supernovae
- Space Exploration and Technology
- Astrophysical Phenomena and Observations
- Advanced Measurement and Metrology Techniques
- Superconducting and THz Device Technology
- History and Developments in Astronomy
- Geophysics and Gravity Measurements
- Galaxies: Formation, Evolution, Phenomena
- Technology Assessment and Management
- Spacecraft Design and Technology
- Atmospheric Ozone and Climate
- Radio Astronomy Observations and Technology
- High-pressure geophysics and materials
- Astrophysics and Cosmic Phenomena
- Spectroscopy and Laser Applications
- Particle Accelerators and Free-Electron Lasers
- Planetary Science and Exploration
California Institute of Technology
2015-2024
NASA Exoplanet Science Institute
2012-2024
Infrared Processing and Analysis Center
1999-2023
Jet Propulsion Laboratory
1999-2018
National Aeronautics and Space Administration
2009-2010
United States Department of the Navy
2009
United States Navy
2009
Metric Systems Corporation (United States)
2005
World Water Watch
2004
Institut für Palliative Care
2001
We describe the contents and functionality of NASA Exoplanet Archive, a database toolset funded by to support astronomers in exoplanet community. The current content includes interactive tables containing properties all published exoplanets, Kepler planet candidates, threshold-crossing events, data validation reports target stellar parameters, light curves from CoRoT missions several ground-based surveys, spectra radial velocity measurements literature. Tools provided work with these include...
\We present the sixth catalog of Kepler candidate planets based on nearly 4 years high precision photometry. This builds legacy previous catalogs released by project and includes 1493 new Objects Interest (KOIs) which 554 are planet candidates, 131 these candidates have best fit radii <1.5 R_earth. brings total number KOIs to 7305 4173 respectively. We suspect that many at low signal-to-noise limit may be false alarms created instrumental noise, discuss our efforts identify such objects....
ABSTRACT We present the seventh Kepler planet candidate (PC) catalog, which is first catalog to be based on entire, uniformly processed 48-month data set. This fully automated employing robotic vetting procedures evaluate every periodic signal detected by Q1–Q17 Data Release 24 (DR24) pipeline. While we prioritize uniform over absolute correctness of individual objects, find that our overall comparable to, and in most cases superior human employed past catalogs. utilize artificial transit...
We present the Kepler Object of Interest (KOI) catalog transiting exoplanets based on searching four years time series photometry (Data Release 25, Q1-Q17). The contains 8054 KOIs which 4034 are planet candidates with periods between 0.25 and 632 days. Of these candidates, 219 new in this include two multi-planet systems (KOI-82.06 KOI-2926.05), ten high-reliability, terrestrial-size, habitable zone candidates. This was created using a tool called Robovetter automatically vets DR25 Threshold...
The Wide Field Infrared Survey Telescope (WFIRST) is a 2.4m space telescope with 0.281 deg^2 field of view for near-IR imaging and slitless spectroscopy coronagraph designed > 10^8 starlight suppresion. As background information Astro2020 white papers, this article summarizes the current design anticipated performance WFIRST. While WFIRST does not have UV imaging/spectroscopic capabilities Hubble Space Telescope, wide surveys hundreds times more efficient. Some most ambitious multi-cycle...
We have observed 14 Herbig Ae/Be (HAEBE) sources with the long-baseline near-IR Palomar Testbed Interferometer. All except two are resolved at 2.2 μm, angular sizes generally ≲5 mas. determine size scales and orientations of μm emission using various models: uniform disks, Gaussians, rings, flat accretion disks inner holes, flared puffed-up rims. Although it is difficult to distinguish different radial distributions, we able place firm constraints on inclinations most sources; seven objects...
We have conducted a survey of young single and multiple systems in the Taurus-Auriga star-forming region with Atacama Large Millimeter Array (ALMA), substantially improving both spatial resolution sensitivity which individual protoplanetary disks these been observed. These ALMA observations can resolve binary separations as small 25--30 AU an average 3$\sigma$ detection level 0.35 mJy, equivalent to disk mass $4 \times 10^{-5}$ M$_{\odot}$ for M3 star. Our sample was constructed from stars...
We report the results of a sensitive K-band survey Herbig Ae/Be disk sizes using 85 m baseline Keck Interferometer. Targets were chosen to span maximum range stellar properties probe size dependence on luminosity and effective temperature. For most targets, measured near-infrared (ranging from 0.2 4 AU) support simple model possessing central optically thin (dust-free) cavity, ringed by hot dust emitting at expected sublimation temperatures (Ts ~1000-1500 K). Furthermore, we find tight...
We report the spectroscopic detection of mid-infrared emission from transiting exoplanet HD 209458b. Using archive data taken with Spitzer IRS instrument, we have determined spectrum 209458b between 7.46 and 15.25 μm. used two independent methods to determine planet spectrum, one differential in wavelength absolute, find results are good agreement. Over much this spectral range, is consistent featureless thermal emission. Between 7.5 8.5 μm, evidence for an unidentified feature. If...
The Keck Interferometer (KI) combined the two 10 m W. M. Observatory telescopes on Mauna Kea, Hawaii, as a long-baseline near- and mid-infrared interferometer. Funded by NASA, it operated from 2001 until 2012. KI used adaptive optics to correct individual wavefronts, well active fringe tracking in all modes for path-length control, including implementation of cophasing provide long coherent integration times. implemented high sensitivity fringe-visibility measurements at H (1.6 μm), K (2.2 L...
We report observations of a possible young transiting planet orbiting previously known weak-lined T-Tauri star in the 7-10 Myr old Orion-OB1a/25-Ori region. The candidate was found as part Palomar Transient Factory (PTF) Orion project. It has photometric transit period 0.448413 +- 0.000040 days, and appears both 2009 2010 PTF data. Follow-up low-precision radial velocity (RV) adaptive optics imaging suggest that is not an eclipsing binary, it unlikely background source blended with target...
ABSTRACT The recent detections of two transit events attributed to the super-Earth candidate K2-18b have provided unprecedented prospect spectroscopically studying a habitable-zone planet outside solar system. Orbiting nearby M2.5 dwarf and receiving virtually same stellar insolation as Earth, would be prime for first detailed atmospheric characterization exoplanet using Hubble Space Telescope ( HST) James Webb JWST ). Here, we report detection third near predicted time Spitzer Telescope....
We present infrared interferometric angular size measurements for the A7IV-V star Altair that indicate a noncircular projected disk brightness distribution. Given known rapid rotation of this star, we model data as arising from an elongated rigid atmosphere. To first order, ellipse may be fitted to our diameter measurements, with major and minor axes 2a = 3.461 ± 0.038 mas 2b 3.037 0.069 mas, respectively, difference 424 79 μas between 2b, axial ratio a/b 1.140 0.029. Assuming apparent...
We present observations of four T Tauri stars using long baseline infrared interferometry from the Palomar Testbed Interferometer. The target sources, Tau N, SU Aur, RY Tau, and DR are all known to be surrounded by dusty circumstellar disks. directly trace inner regions (<1 AU) disk can used constrain physical properties this material. For three sources observed, emission is clearly resolved. first use geometric models characterize region size, which ranges 0.04 0.3 AU in radius. then Monte...
We determine inner disk sizes and temperatures for four solar-type (1-2 M$_{\odot}$) classical T Tauri stars (AS 207A, V2508 Oph, AS 205A, PX Vul) using 2.2 $μ$m observations from the Keck Interferometer. Nearly contemporaneous near-IR adaptive optics imaging photometry, optical high-dispersion spectroscopy are used to distinguish contributions disks central in interferometric observations. In addition, spectroscopic photometric data provide estimates of stellar properties, mass accretion...
We present spatially resolved near-IR spectroscopic observations of 15 young stars. Using a grism spectrometer behind the Keck interferometer, we obtained an angular resolution few milliarcseconds and spectral 230, enabling probes both gas dust in inner disks surrounding target find that size emission typically increases with wavelength, indicating hot, presumably gaseous material within sublimation radius. Our data also clearly indicate Brγ arising from hot hydrogen gas, suggest presence...
We describe the Keck Interferometer nuller theory of operation, data reduction, and on-sky performance, particularly as it applies to exozodiacal dust key science program that was carried out between 2008 February 2009 January. review implementation, including detailed phasor processing involved in implementing null-peak mode used for sequencing observing. then Level 1 reduction convert instrument telemetry streams raw null leakages, 2 provide calibrated leakages. The uses conservative,...
We have conducted a survey of 17 wide (>100 AU) young binary systems in Taurus with the Atacama Large Millimeter Array (ALMA) at two wavelengths. The observations were designed to measure masses circumstellar disks these as an aid understanding role multiplicity star and planet formation. ALMA had sufficient resolution localize emission within system. Disk was detected around all primaries 10 secondaries, disk low 10−4 M☉. compare properties our sample population known find that from this...
$K2$'s Campaign 9 ($K2$C9) will conduct a $\sim$3.7 deg$^{2}$ survey toward the Galactic bulge from 7/April through 1/July of 2016 that leverage spatial separation between $K2$ and Earth to facilitate measurement microlens parallax $\pi_{\rm E}$ for $\gtrsim$127 microlensing events. These include several are planetary in nature as well many short-timescale events, which potentially indicative free-floating planets (FFPs). satellite measurements turn allow direct masses distances lensing...
We report novel, high angular resolution interferometric measurements that imply the near-infrared nuclear emission in NGC 4151 is unexpectedly compact. have observed nucleus of at 2.2 μm using two 10 m Keck telescopes as an interferometer and find a marginally resolved source ≤0.1 pc diameter. Our rule out models which majority K-band produced on scales larger than this size. The interpretation our measurement most consistent with other observations mainly originates directly central...
We present near-infrared observations of T Tauri and Herbig Ae/Be stars with a spatial resolution few milli-arcseconds spectral ~2000. Our spatially resolve gas dust in the inner regions protoplanetary disks, spectrally broad-linewidth emission from Brackett gamma transition hydrogen gas. use technique spectro-astrometry to determine centroids different velocity components this gaseous at precision orders magnitude better than angular resolution. In all sources, we find be more compact or...
We present high angular resolution observations with the Keck Interferometer, high-dispersion spectroscopic Keck/NIRSPEC, and near-IR photometric from PAIRITEL of a sample 11 solar-type T Tauri stars in nine systems. use these to probe circumstellar material within 1 AU young stars, measuring circumstellar-to-stellar flux ratios size scales 2.2 μm emission. Our spans range stellar luminosities mass accretion rates, allowing investigation potential correlations between inner disk properties...
The main-sequence solar-type star HD 69830 has an unusually large amount of dusty debris orbiting close to three planets found via the radial velocity technique. In order explore dynamical interaction between dust and planets, we have performed multi-epoch photometry spectroscopy system over several orbits outer dust. We find no evidence for changes in either or its composition, with upper limits 5%–7% (1σ per spectral element) on variability spectrum 1 year, 3.3% (1σ) broadband disk...
Binary star-formation theory predicts that close binaries (a<100 AU) will experience periodic pulsed accretion events as streams of material form at the inner edge a circumbinary disk, cross dynamically cleared gap, and feed circumstellar disks or accrete directly onto stars. The archetype for pulsed-accretion is eccentric, short-period, classical T Tauri binary DQ Tau. Low-cadence (~daily) broadband photometry has shown brightening near most periastron passages, just numerical simulations...