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Register a new userSmall and Nearby NEOs Observed by NEOWISE During the First Three Years of Survey: Physical Properties
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Automated asteroid detection routines set requirements on the number of detections, signal-to-noise ratio, and the linearity of the expected motion in order to balance completeness, reliability, and time delay after data acquisition when identifying moving object tracklets. However, when the full-frame data from a survey are archived, they can be searched later for asteroids that were below the initial detection thresholds. We have conducted such a search of the first three years of the reactivated NEOWISE data, looking for near-Earth objects discovered by ground-based surveys that have previously unreported thermal infrared data. Using these measurements, we can then perform thermal modeling to measure the diameters and albedos of these objects. We present new physical properties for 116 Near-Earth Objects found in this search.
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Thermal infrared measurements of near-Earth objects provide critical data for constraining their physical properties such as size. The NEOWISE mission has been conducting an all-sky infrared survey to gather such data and improve our understanding of this population. While automated routines are employed to identify the majority of moving objects detected by NEOWISE, a subset of objects will have dynamical properties that fall outside the window detectable to these routines. Using the population of known near-Earth objects, we have conducted a manual search for detections of these objects that were previously unreported. We report 303 new epochs of observations for 299 unique near-Earth objects of which 239 have no previous physical property characterization from the NEOWISE Reactivation mission. As these objects are drawn from a list with inherent optical selection biases, the distribution of measured albedos is skewed to higher values than is seen for the diameter-selected population detected by the automated routines. These results demonstrate the importance and benefit of periodic searches of the archival NEOWISE data.
Enhancements to the science data processing pipeline of NASAs Wide-field Infrared Explorer (WISE) mission, collectively known as NEOWISE, resulted in the detection of $>$158,000 minor planets in four infrared wavelengths during the fully cryogenic portion of the mission. Following the depletion of its cryogen, NASAs Planetary Science Directorate funded a four month extension to complete the survey of the inner edge of the Main Asteroid Belt and to detect and discover near-Earth objects (NEOs). This extended survey phase, known as the NEOWISE Post-Cryogenic Survey, resulted in the detection of $sim$6500 large Main Belt asteroids and 88 NEOs in its 3.4 and 4.6 $mu$m channels. During the Post-Cryogenic Survey, NEOWISE discovered and detected a number of asteroids co-orbital with the Earth and Mars, including the first known Earth Trojan. We present preliminary thermal fits for these and other NEOs detected during the 3-Band Cryogenic and Post-Cryogenic Surveys.
We report on the discovery of three transiting planets around GJ~9827. The planets have radii of 1.75$_{-0.12}^{+0.11 }$, 1.36$_{- 0.09 }^{+ 0.09}$, and 2.10$_{- 0.15 }^{+ 0.15 }$~R$_{oplus}$, and periods of 1.20896, 3.6480, and 6.2014 days, respectively. The detection was made in Campaign 12 observations as part of our K2 survey of nearby stars. GJ~9827 is a $V = 10.39$~mag K6V star at distance of 30.3 parsecs and the nearest star to be found hosting planets by Kepler and K2. The radial velocity follow-up, high resolution imaging, and detection of multiple transiting objects near commensurability drastically reduce the false positive probability. The orbital periods of GJ~9827~b, c and d planets are very close to the 1:3:5 mean motion resonance. Our preliminary analysis shows that GJ~9827 planets are excellent candidates for atmospheric observations. Besides, the planetary radii span both sides of the rocky and gaseous divide, hence the system will be an asset in expanding our understanding of the threshold.
We present results from the first three years of observations of moving group targets in the SEEDS high-contrast imaging survey of exoplanets and disks using the Subaru telescope. We achieve typical contrasts of ~10^5 at 1 and ~10^6 beyond 2 around 63 proposed members of nearby kinematic moving groups. We review each of the kinematic associations to which our targets belong, concluding that five, beta Pictoris (~20 Myr), AB Doradus (~100 Myr), Columba (~30 Myr), Tucana-Horogium (~30 Myr), TW Hydrae (~10 Myr), are sufficiently well-defined to constrain the ages of individual targets. Somewhat less than half of our targets are high-probability members of one of these moving groups. For all of our targets, we combine proposed moving group membership with other age indicators where available, including Ca II HK emission, X-ray activity, and rotation period, to produce a posterior probability distribution of age. SEEDS observations discovered a substellar companion to one of our targets, kappa And, a late B star. We do not detect any other substellar companions, but do find seven new close binary systems, of which one still needs to be confirmed. A detailed analysis of the statistics of this sample, and of the companion mass constraints given our age probability distributions and exoplanet cooling models, will be presented in a forthcoming paper.
The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft has been conducting a two-band thermal infrared survey to detect and characterize asteroids and comets since its reactivation in Dec 2013. Using the observations collected during the fourth and fifth years of the survey, our automated pipeline detected candidate moving objects which were verified and reported to the Minor Planet Center. Using these detections, we perform thermal modeling of each object from the near-Earth object and Main Belt asteroid populations to constrain their sizes. We present thermal model fits of asteroid diameters for 189 NEOs and 5831 MBAs detected during the fourth year of the survey, and 185 NEOs and 5776 MBAs from the fifth year. To date, the NEOWISE Reactivation survey has provided thermal model characterization for 957 unique NEOs. Including all phases of the original WISE survey brings the total to 1473 unique NEOs that have been characterized between 2010 and the present.
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