SETI Institute scientists present at IAU General Assembly 2015
IAU General Assembly August 3 - 14, 2015
Progress in Identifying Fe I Level Energies and Lines from Stellar Spectra
Abstract Body: The spectrum of the Fe I atom is critical to many areas of astrophysics and beyond, the vital input necessary to characterize the spectral absorption and emission of the atomic and molecular systems that pervade stars, stellar nebulae, exploding supernovae, and the interstellar and intergalactic medium, from the local environment to the highest redshifts. Yet measurements of the energies of its high-lying levels remain seriously incomplete, despite extensive efforts incorporating both laboratory sources and the solar spectrum. Peterson & Kurucz (2015, ApJS, 216, 1) reported the first results from a new approach, one which uses the spectra of sharp-lined stars of near-solar temperature to identify level energies. By matching predicted to observed stellar line wavelengths and strengths transition by transition, the upper energies of 66 Fe I levels were established. Many new levels are at higher energies than can be determined in the laboratory, including several that lie above the Fe I ionization energy. However, many more unidentified levels remain, especially those levels whose strongest lines fall in wavelength regions where stellar data is marginal or missing. Here we update the progress in this effort, and outline where new data are most urgently required and why.
Checking for Energetic Flares on Old Halo K Dwarfs with Kepler 2
Abstract Body: This talk describes the unique opportunity offered by Kepler 2 (K2) observations of halo fields to establish whether energetic flaring occurs on stars so old that any global magnetic dynamo present at star formation has died away. Such work is being proposed to Living With a Star as a byproduct of identifying red giants at very large distances from the Galactic plane, 10 to 100 kpc. We have proposed the latter to K2 for the halo field C6, and plan to do so for the upcoming K2 halo fields C8, C10, and C12, to obtain hundreds of giants at these distances. To remove all metallicity bias, our targets include all K2 EPIC stars with Sloan SDSS ugriz photometry, g-r from 0.6 to 1.1, proximity > 12'' (if present) to minimize contamination, and proper motion below 11 mas to remove most foreground stars. Kepler magnitudes Kp are between 16 and 18.5, where long-cadence K2 observations can detect p-mode oscillations of red giants and measure the frequency of maximum power Î½<sub>max</sub>. However, only about 3% of these targets will be halo giants. The remainder will be intervening dwarfs, which at these magnitudes will be more than 1 kpc from the Galactic plane and thus members of the old halo population. Both spotted stars and interacting binaries are recognizable from their light curves; single dwarfs show simple shot noise. Using the properties of superflares as seen in long-cadence Kepler data, we will identify flares and flaring stars among this sample of old halo K dwarfs. Subsequent C6 spectroscopy, if desired, can be pursued from both hemispheres, and need cover an area only four degrees square. Whether positive or negative, the results will constrain mechanisms for energetic flaring on the Sun.
Identifying Remote Halo Giants in High-Latitude Fields with Kepler 2
Abstract Body: This talk describes halo-field K2 proposals submitted for C6, and planned for C8, C10, and C12, to identify red giants at distances from the Galactic plane between 10 and 100 kpc. This complements KASC WG8 Galactic Archaeology proposals by identifying and characterizing very remote halo red giants, and also in contributing to MAST a grid of high-resolution spectral calculations for giants useful for determining temperatures, gravities, and abundances from optical spectroscopy. Unlike previous surveys, our targets are unbiased in metallicity, consisting of all EPIC stars with SDSS ugriz photometry, g-r from 0.6 to 1.1, proximity > 12" (if present) to minimize contamination, and proper motion < 11 mas to remove most foreground stars. Kepler magnitudes Kp are between 16 and 18.5, where we establish that K2 can detect p-mode oscillations of red giants and measure the frequency of maximum power νmax. We also show that for these minimally-reddened stars, the g-r color alone yields the effective temperature Teff to 100K for giants with metallicity [Fe/H] below -1. We then illustrate how [Fe/H] will be estimated from νmax from the dependence of red-giant luminosity on metallicity at a given g-r. Only about 3% of these targets will be halo giants. The remainder will be intervening dwarfs, which at these magnitudes will be more than 1 kpc from the Galactic plane and thus members of the old halo population. This sample is valuable in its own right, for problems as diverse as the nature of the thick disk - halo transition and the occurrence of flaring on cool dwarfs so old that any original global magnetic dynamo has died away.
X. Huang; D. W. Schwenke; T. J. Lee
IR Line Lists of SO2 and CO2 Isotopologues for Atmospheric Modeling on Venus and Exoplanets
Abstract Body: For atmospheric characterization and simulations in Venus and other Exoplanetary environments, scientists need high resolution IR opacity data for important astronomical molecules such as CO2 and SO2. Existing high-resolution IR databases are far from complete for many CO2 minor isotopologues and all SO2 isotopologues. Recently we presented Ames-296K line lists for 5 SO2 symmetric isotopologues: 626, 636, 646, 666 and 828. For CO2, we have reported Ames-296K and Ames-1000K IR line lists for 13 isotopologues, including symmetric species 626, 636, 646, 727, 737, 828, 838, and asymmetric species 627, 628, 637, 638, 728, 738. CO2 line shape parameters were also determined for four different temperature ranges: Mars, Earth, Venus, and Higher temperature. General line position prediction accuracy is 0.01 – 0.02 cm−1 for wavenumber range up to 5000 cm-1 (for SO2) or 13,000 cm-1 (for CO2). Predicted transition intensities usually agree with experimental measurements to 85-95% or better. With such prediction accuracies, these SO2 and CO2 IR line lists are the best available alternatives for those spectra gaps missing from spectroscopic databases such as HITRAN and CDMS. Our line lists are based on the ”Best Theory + High-Res Expt. Data” strategy, i.e. using ab initio potential energy surfaces refined with selected reliable high resolution experimental data, and high quality CCSD(T)/aug-cc-pVQ(or Q+d)Z dipole moment surfaces. Currently the Ames-296K lists are available at http://huang.seti.org. We will demonstrate the accuracy and reliability of Ames-296K line lists by comparing with latest SO2 and CO2 experimental data. In addition, we will discuss difficulties, future improvements and other molecules we have been working on (or plan to).
J. P. Simpson; K. Sellgren; S. Ramirez; A. Cotera; D. An
Three New Candidate Planetary Nebulae near the Galactic Center
Abstract Body: We report the discovery of three candidate planetary nebulae (PNe) detected in lines of sight close to our Galactic Center: G0.098-0.051, G0.399+0.208, and G359.963-0.120. These objects are identified by being compact continuum sources with exceptionally high excitation as seen in spectra of forbidden lines taken with Spitzer Space Telescope's Infrared Spectrograph and downloaded from the Spitzer Heritage Archive. In particular, the high excitation lines include [Na III] 7.32 micron, [O IV] 25.9 micron, and [Ne V] 14.3 and 24.3 micron. Such lines are not seen in Galactic H II regions but only are found in PNe and supernova remnants; we exclude the last by the existance of the co-located continuum sources of size a few arcsec. We note that none of these sources has any significant associated emission from polycyclic aromatic hydrocarbons, which is otherwise common in the Galactic Center and in PNe. We will present spectra, abundance analyses, additional data from radio and near-infrared telescopes, and photoionization and shock models computed with Cloudy (Ferland et al. 2013) and MAPPINGS III (Allen et al. 2008).
J. P. Simpson; M. Burton; A. Cotera; M. Cunningham; N. Lo
An EGO That Is Not Aligned With Its Disk Axis
Abstract Body: The infrared source G333.466-0.164 (IRAS 16175-5002) was discovered to contain a 4.5 micron emission feature (extended green object, EGO) in images taken with Spitzer's Infrared Array Camera in 2004. EGOs appear to define the location of outflows from massive young stellar objects (MYSOs) and have been attributed to both emission from molecular hydrogen or CO in the shocked outflow and to scattered light from the outflow cavity. We confirmed that there is a MYSO at the south end of the 15'' long, thin EGO from spectra taken with Spitzer's Infrared Spectrograph in 2009 (Simpson et al. 2012, MNRAS, 419, 211). To further characterize G333.466-0.164 we obtained 12.3 and 24.5 micron images with T-ReCS on Gemini South. Although the MYSO itself is not detected at 12.3 micron, we clearly resolve an elongated source at the location of the MYSO at 24.5 micron with the 0.76" FWHM resolution of Gemini. The elongated region has major and minor axes 2.5'' and 1.5'', respectively, where the position angle of the major axis is 147 pm 5 degrees east of north. For a distance of 3.6 kpc, this corresponds to a size of 9000 AU by 5400 AU. We contrast the position angle of the source to that of the EGO, which is approximately -10 degrees east of north measured from the MYSO. Methanol masers have been measured in G333.466-0.164 by Caswell et al. (2011, MNRAS, 417, 1964) and Voronkov et al. (2014, MNRAS, 439, 258). The 6.7 GHz Class II maser is found at the position of the MYSO and the 36 and 44 GHz Class I masers, which are excited by shocks, are found in positions coinciding with the EGO and also in a line perpendicular to the EGO, in an area obscured by an optically thick dust lane. Voronkov et al. suggest that the actual outflow lies between the two lines of Class I masers in the northeast direction; this is in excellent agreement with the northeast-oriented minor axis of the elongated feature that we observe at 24.5 micron. Thus we identify the 24.5 micron source as the disk of the MYSO. We additionally detect a warm-dust counterpart to the EGO at both 12.3 and 24 micron; thus it is not unlikely that both the EGO and the masers are located along the cavity wall.
J. Catanzarite; J. M. Jenkins; S. D. McCauliff; C. Burke; S. Bryson; N. Batalha; J. Coughlin; J. Rowe; F. Mullally; s. thompson; S. Seader; J. Twicken; J. Li; R. Morris; J. Smith; M. Haas; J. Christiansen; B. Clarke
Inferring Planet Occurrence Rates With a Q1-Q17 Kepler Planet Candidate Catalog Produced by a Machine Learning Classifier
Abstract Body: NASA's Kepler Space Telescope monitored the photometric variations of over 170,000 stars, at half-hour cadence, over its four-year prime mission. The Kepler pipeline calibrates the pixels of the target apertures for each star, produces light curves with simple aperture photometry, corrects for systematic error, and detects threshold-crossing events (TCEs) that may be due to transiting planets. The pipeline estimates planet parameters for all TCEs and computes diagnostics used by the Threshold Crossing Event Review Team (TCERT) to produce a catalog of objects that are deemed either likely transiting planet candidates or false positives. We created a training set from the Q1-Q12 and Q1-Q16 TCERT catalogs and an ensemble of synthetic transiting planets that were injected at the pixel level into all 17 quarters of data, and used it to train a random forest classifier. The classifier uniformly and consistently applies diagnostics developed by the Transiting Planet Search and Data Validation pipeline components and by TCERT to produce a robust catalog of planet candidates. The characteristics of the planet candidates detected by Kepler (planet radius and period) do not reflect the intrinsic planet population. Detection efficiency is a function of SNR, so the set of detected planet candidates is incomplete. Transit detection preferentially finds close-in planets with nearly edge-on orbits and misses planets whose orbital geometry precludes transits. Reliability of the planet candidates must also be considered, as they may be false positives. Errors in detected planet radius and in assumed star properties can also bias inference of intrinsic planet population characteristics. In this work we infer the intrinsic planet population, starting with the catalog of detected planet candidates produced by our random forest classifier, and accounting for detection biases and reliabilities as well as for radius errors in the detected population.Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA, Science Mission Directorate.
J. L. Christiansen; B. Clarke; C. Burke; S. Seader; J. M. Jenkins; J. Twicken; J. Smith; N. Batalha; M. Haas; S. Thompson
Measuring the Detection Efficiency of the Kepler Pipeline: The First Results from a Simulated Transit Experiment Spanning the Full Observation Baseline
Abstract Body: As the full Kepler dataset is analysed and made available, the Kepler project has published a series of planet candidate lists. In order for both the project and the community to determine the true planet occurrence rates from these candidate lists, we need to measure the detection efficiency of the Kepler pipeline from which the candidates are produced, that is, the rate at which planets are missed in the analysis. We present here the preliminary results from the first empirical measurement of the detection efficiency of the pipeline on the full seventeen quarters of data, extending our previous measurements using one and four quarters of data. For the first time, we are also able to use the identical data products and pipeline versions as those used to generate the Q1-Q17 planet candidate catalogue, and as a consequence, the measured detection efficiency can be used directly in the inference of the planet occurrence rates. In particular, we examine the impact of the large rate of false positives in the Kepler planet candidate lists at periods of 200-400 days, due to temperature-dependent electronic artifacts in the Kepler CCDs, on the detection of real planets at those periods, which are critical to habitable zone occurrence rate calculations
The First Uniform Kepler Q1 - Q17 Planet Candidate Catalog
Abstract Body: We present an update to the Kepler planet-candidate catalog based on the entire Kepler mission dataset. This includes all 17 quarters of data, uniformly processed from pixels to planets. We discuss improvements to our planet-candidate vetting procedure, which is now completely automated and yields specific categories of false positives. For the first time, we also inject transits into all 17 quarters of data at the pixel-level and use these results to quantitatively evaluate the accuracy of our vetting procedures. Together these improvements allow us to disposition every known TCE and KOI quickly and uniformly, thus enabling accurate planet occurrence rate calculations. The current catalog is available at the Exoplanet Archive (http://exoplanetarchive.ipac.caltech.edu), and the light curves and pixel-level data are available at MAST (http://archive.stsci.edu/kepler)
J. Li; C. Burke; J. M. Jenkins; E. Quintana; J. Rowe; S. Seader; P. Tenenbaum; J. Twicken
Transit Model Fitting in Processing Four Years of Kepler Science Data: New Features and Performance
Abstract Body: We present new transit model fitting features and performance of the latest release (9.3, March 2015) of the Kepler Science Operations Center (SOC) Pipeline, which will be used for the final processing of four years of Kepler science data later this year. Threshold Crossing Events (TCEs), which represent transiting planet detections, are generated by the Transiting Planet Search (TPS) component of the pipeline and subsequently processed in the Data Validation (DV) component. The transit model is used in DV to fit TCEs and derive parameters that are used in various diagnostic tests to validate the planet detections. The standard limb-darkened transit model includes five fit parameters: transit epoch time (i.e. central time of first transit), orbital period, impact parameter, ratio of planet radius to star radius and ratio of semi-major axis to star radius. In the latest Kepler SOC pipeline codebase, the light curve of the target for which a TCE is generated is also fitted by a trapezoidal transit model with four parameters: transit epoch time, depth, duration and ratio of ingress time to duration. The fitted trapezoidal transit model is used in the diagnostic tests when the fit with the standard transit model fails or when the fit is not performed, e.g. for suspected eclipsing binaries. Additional parameters, such as the equilibrium temperature and effective stellar flux (i.e. insolation) of the planet candidate, are derived from the transit model fit parameters to characterize pipeline candidates for the search of Earth-size planets in the habitable zone. The uncertainties of all derived parameters are updated in the latest codebase to account for the propagated errors of the fit parameters as well as the uncertainties in stellar parameters. The results of the transit model fitting for the TCEs identified by the Kepler SOC Pipeline are included in the DV reports and one-page report summaries, which are accessible by the science community at NASA Exoplanet Archive (http://exoplanetarchive.ipac.caltech.edu/). Funding for the Kepler Mission has been provided by the NASA Science Mission Directorate.
S. E. Mullally; F. Mullally; J. Coughlin; K. TCERT
A New Metric to Decide if a Photometric Signal is Transit-Shaped
Abstract Body: The Kepler space mission has discovered an unprecedented number of transiting planet candidates in the sublime photometric data it collected over 4 years. These planet catalogs, until now, have been created by manually inspecting the tens of thousands of TCEs (Threshold Crossing Events, or possible periodic transiting events) that are found using the Kepler pipeline (Seader et al. 2014). Only the decision about whether the transit came from a background eclipsing binary was done by an automated process in previous catalogs (see Mullally et al. 2014). Going forward, in order to create a consistently vetted catalog that can be produced with less manual effort, the first planet catalog based on the entire set of Kepler data (data release 24) will be fully automated. In order to accomplish this task, we were required to invent new metrics to account for decisions previously made by scientists. Here, we describe a new metric being used to determine if a TCE is shaped like known transits. This metric uses the locality preserving projections (LPP) dimensionality reduction algorithm (He & Niyogi 2004; van der Maaten et al. 2009) on the folded and binned light curves to separate the sinusoidal type TCEs from those showing a true transit signature. We show how well the metric performs on both the current set of TCEs and on planet events injected into the data
Understanding Kepler’s Objects of Interest
Abstract Body: We present an analysis of the Kepler Object of Interest Catalogue based on inversion tests and complete MCMC modeling to provide posterior distributions. We show how planet-candidates, eclipsing binaries, background blends and false-alarms assemble into populations based on fundamental transit parameters such as transit duration and depth. We present reliability rates of the KOI databased to estimate the number of planets, false-positives and false-alarm. Our work identifies regions of parameter space that allow one to identify planets with low false-positive contamination. We also present a 'HR-diagram' based on exoplanetary transits and measure the underlying eccentricity distribution and the rate of the stellar blends due to binarity
J. C. Smith; R. Morris; S. Bryson; J. M. Jenkins; D. Caldwell
K2 Mission Light Curves
Abstract Body: The K2 mission is now generating light curves for its ecliptic-field campaigns. Producing good photometry for K2 is more challenging than for Kepler's prime mission because periodic thruster firings are used to compensate for the loss of two reaction wheels. These firings, referred to as "roll tweaks", result in spacecraft rotation along the barrel axis and high corresponding image motion. The resulting motion-dominated systematic errors are dramatically different than the focus-dominated systematic errors experienced during the prime mission. They also make it challenging to properly identify and remove flux from background objects present in the optimal apertures. We summarize these challenges and describe the resulting modifications to the Kepler pipeline for the processing of K2 data. The quality of the K2 mission light curves is characterized.
J. Twicken; L. Brownston; J. Catanzarite; B. Clarke; M. Cote; F. Girouard; J. Li; S. McCauliff; S. Seader; P. Tenenbaum; B. Wohler; J. M. Jenkins; N. Batalha; S. Bryson; C. Burke; D. Caldwell
Characterization and Validation of Transiting Planets in the Kepler and TESS Pipelines
Abstract Body: Light curves for Kepler targets are searched for transiting planet signatures in the Transiting Planet Search (TPS) component of the Science Operations Center (SOC) Processing Pipeline. Targets for which the detection threshold is exceeded are subsequently processed in the Data Validation (DV) Pipeline component. The primary functions of DV are to (1) characterize planets identified in the transiting planet search, (2) search for additional transiting planet signatures in light curves after modeled transit signatures have been removed, and (3) perform a comprehensive suite of diagnostic tests to aid in discrimination between true transiting planets and false positive detections. DV output products include extensive reports by target, one-page report summaries by planet candidate, and tabulated planet model fit and diagnostic test results. The DV products are employed by humans and automated systems to vet planet candidates identified in the pipeline. The final revision of the Kepler SOC codebase (9.3) was released in March 2015. It will be utilized to reprocess the complete Q1-Q17 data set later this year. At the same time, the SOC Pipeline codebase is being ported to support the Transiting Exoplanet Survey Satellite (TESS) Mission. TESS is expected to launch in 2017 and survey the entire sky for transiting exoplanets over a period of two years. We describe the final revision of the Kepler Data Validation component with emphasis on the diagnostic tests and reports. This revision also serves as the DV baseline for TESS. The diagnostic tests exploit the flux (i.e., light curve), centroid and pixel time series associated with each target to facilitate the determination of the true origin of each purported transiting planet signature. Candidate planet detections and DV products for Kepler are delivered to the Exoplanet Archive at the NASA Exoplanet Science Institute (NExScI). The Exoplanet Archive is located at exoplanetarchive.ipac.caltech.edu. Funding for the Kepler and TESS Missions has been provided by the NASA Science Mission Directorate.
A. Cotera; b. Whitney; E. Rodgers
Combined Light Curves and Variable High Resolution Imaging of Taurus YSOs
Abstract Body: Young Stellar Objects (YSOs) were first identified as a distinct class based on their intrinsic variability. For Class I-Class II YSOs, the suggested underlying physical mechanisms fall primarily into two categories: (i) magnetic disk accretion onto the photosphere, resulting in a hot spot; or (ii) shadowing by an induced warp in the accretion disk. We present new light curves for seven Taurus YSOs obtained with the NOAO WIYN telescope infrared camera WHIRC over 14 nights in December 2014. All of the observed objects also have at least two epochs of high resolution HST NICMOS infrared images in which variations have been observed. By combining these two different data sets with radiation transfer models of the objects, we will investigate the physical processes of variability for a group of objects where the geometrical effects are well constrained.
Abstract Body: Meteorites have long been known to offer a unique window into planetary formation processes at the time of solar system formation and into the materials that rained down on Earth at the time of the origin of life. Their material properties determine the impact hazard of Near Earth Asteroids. Some insight into how future laboratory studies of meteorites and laboratory astrophysics simulations of relevant physical processes can help address open questions in these areas and generate new astronomical observations, comes from what was learned from the recent laboratory studies of freshly fallen meteorites. The rapid recovery of Almahata Sitta (a polymict Ureilite), Sutter's Mill (a CM chondrite regolith breccia), Novato (an L6 chondrite), and Chelyabinsk (an LL5 chondrite) each were followed by the creation of a meteorite consortium, which grew to over 50 researchers in the case of Chelyabinsk. New technologies were used to probe the organic content of the meteorites as well as their magnetic signatures, isotopic abundances, trapped noble gasses, and cosmogenic radio nucleides, amongst others. This has resulted in fascinating insight into the nature of the Ureilite parent body, the likely source region of the CM chondrites in the main asteroid belt, and the collisional environment of the CM parent body. This work has encouraged follow-up in the hope of catching more unique materials. Rapid response efforts are being developed that aim to recover meteorites as pristinely as possible from falls for which the approach orbit was measured. A significant increase in the number of known approach orbits for different meteorite types will help tie meteorite types to their asteroid family source regions. Work so far suggests that future laboratory studies may recognize multiple source regions for iron-rich ordinary chondrites, for example. Hope is that these source regions will give insight into the material properties of impacting asteroids. At least some future laboratory astrophysics experiments are expected to focus on clarifying the physical conditions during small asteroid impacts such as the one responsible for the Chelyabinsk airburst and the over 1200 injured who needed medical attention.
Active Near Earth Asteroids
Abstract Body: Past activity from Near Earth Asteroids is recorded in the meteoroid streams that cause our meteor showers. Automated meteoroid orbit surveys by photographic, low-light video, specular radar, and head-echo radar reflections are providing the first maps of meteor shower activity at different particle sizes. There are distinct differences in particle size distributions among streams. The underlaying mechanisms that created these streams are illuminated: fragmentation from spin-up or thermal stresses, meteoroid ejection by water vapor drag, and ejection of icy particles by CO and CO2 sublimation. The distribution of the meteoroid orbital elements probe the subsequent evolution by planetary perturbations and sample the range of dynamical processes to which Near Earth Asteroids are exposed. The non-stream "sporadic" meteors probe early stages in the evolution from meteoroid streams into the zodiacal dust cloud. We see that the lifetime of large meteoroids is generally not limited by collisions. Results obtained by the CAMS video survey of meteoroid orbits are compared to those from other orbit surveys. Since October 2010, over 200,000 meteoroid orbits have been measured. First results from an expansion into the southern hemisphere are also presented, as are first results from the measurement of main element compositions. Among the many streams detected so far, the Geminid and Sextantid showers stand out by having a relatively high particle density and derive from parent bodies that appear to have originated in the main belt.
L. A. Benner; M. Brozovic; J. D. Giorgini; J. S. Jao; C. G. Lee; P. A. Taylor; E. S. Howell; M. W. Busch; H. Ford; F. Ghigo; M. C. Nolan; M. A. Slade; K. J. Lawrence; J. E. Richardson; E. G. Rivera-Valentin; A. Rozek
Radar Imaging of Binary Near-Earth Asteroid (357439) 2004 BL86
Abstract Body: We report radar observations of near-Earth asteroid 2004 BL86 obtained during 2015 Jan. 26-31 at the 70 m and 34 m Goldstone facilities, Arecibo, Green Bank, and elements of the Very Long Baseline Array. 2004 BL86 approached within 0.0080 au (3.1 lunar distances) on Jan. 26, the closest known approach by any object with an absolute magnitude brighter than ~19 until 2027. Prior to the encounter, virtually nothing was known about its physical properties other than its absolute magnitude of 19, which suggested a diameter within a factor of two of 500 m. Due to its size and the extremely close approach, 2004 BL86 was a very strong radar target that provided an outstanding opportunity for radar imaging and physical characterization. The radar images confirmed photometric results reported by Pravec et al. (2015, CBET 4063) that 2004 BL86 is a binary system. This is the 43<sup>rd</sup> near-Earth asteroid binary detected by radar. Delay-Doppler images placed thousands of 3.75 m-resolution pixels on the object and reveal a rounded and oblate primary with an equatorial diameter of ~300 m, suggesting it is optically-bright, evidence for ridges, small-scale topography including boulders, and a large angular feature near one of the poles. A preliminary estimate for the diameter of the secondary is ~70 m. The images hint that the secondary's rotation is synchronous with its orbital period. The observations also yielded the first detection of an asteroid with a new 80 kW C-band radar (7190 MHz, 4.2 cm) at the 34 m DSS-13 antenna at the Goldstone Deep Space Communications Complex. This new radar can achieve a range resolution up to 1.875 m/pixel that is twice as fine as the highest resolution previously achievable.
J. M. Jenkins*; J. Twicken; N. Batalha; D. Caldwell; W. Cochran; M. Endl; D. Latham; G. Esquerdo; S. Seader; A. Bieryla; E. Petigura; D. Ciardi; G. Marcy; H. Isaacson; J. Rowe; G. Torres; D. Huber; S. Bryson; L. A. Buchhave; I. Ramirez; A. Wolfgang; J. Li; J. Campbell; C. Henze; W. Borucki
A 1.6 Earth Radius Planet in the Habitable Zone of a G2 Star
Abstract Body: We report on the discovery and validation a transiting planet identified by a search through the four years of data collected by NASA’s Kepler Mission. This possibly rocky 1.63-Re planet orbits its G2 host star every 384.843 days, one of the longest orbital periods for a terrestrial exoplanet to date. The likelihood that this planet has a rocky composition lies between 43% and 58%. The star has an effective temperature of 5757 ± 85 K and a log g of 4.32 ± 0.09. At a mean orbital separation of 1.046 AU, this small planet is within the habitable zone of its star, experiencing only 10% more flux than Earth receives from the Sun today. The star is slightly larger and older than the Sun, with a present radius of 1.11 Rsun and an estimated age of ~6 Gyr. Thus, this planet has always been in the habitable zone and will remain there for another ∼3 Gyr.
P. K. Harman; D. E. Backman; C. Clark
NASA Stratospheric Observatory For Infrared Astronomy (SOFIA) Airborne Astronomy Ambassador Abstract Body: SOFIA is an airborne observatory, capable of making observations that are impossible for even the largest and highest ground-based telescopes, and inspires instrumentation development.
SOFIA is an 80% - 20% partnership of NASA and the German Aerospace Center (DLR), consisting of a modified Boeing 747SP aircraft carrying a diameter of 2.5 meters (100 inches) reflecting telescope. The SOFIA aircraft is based at NASA Armstrong Flight Research Center, Building 703, in Palmdale, California. The Science Program Office and Outreach Office is located at NASA Ames Research center. SOFIA is one of the programs in NASA's Science Mission Directorate, Astrophysics Division.
SOFIA will be used to study many different kinds of astronomical objects and phenomena, including star birth and death, formation of new solar systems, identification of complex molecules in space, planets, comets and asteroids in our solar system, nebulae and dust in galaxies, and ecosystems of galaxies.
Airborne Astronomy Ambassador Program:
The SOFIA Education and Communications program exploits the unique attributes of airborne astronomy to contribute to national goals for the reform of science, technology, engineering, and math (STEM) education, and to the elevation of public scientific and technical literacy.
SOFIA’s Airborne Astronomy Ambassadors (AAA) effort is a professional development program aspiring to improve teaching, inspire students, and inform the community. To date, 55 educators from 21 states; in three cohorts, Cycles 0, 1 and 2; have completed their astronomy professional development and their SOFIA science flight experience. Cycle 3 cohort of 28 educators will be completing their flight experience this fall. Evaluation has confirmed the program’s positive impact on the teacher participants, on their students, and in their communities. Teachers have incorporated content knowledge and specific components of their experience into their curricula, and have given hundreds of presentations and implemented teacher professional development workshops. Their efforts have impacted thousands of students and teachers.
H. Valizadegan*; R. Martin; S. D. McCauliff; J. M. Jenkins; J. Catanzarite; N. C. Oza
Towards Automatic Classification of Exoplanet-Transit-Like Signals: A Case Study on Kepler Mission Abstract Body: Building new catalogues of planetary candidates, astrophysical false alarms, and non-transiting phenomena is a challenging task that currently requires a reviewing team of astrophysicists and astronomers. These scientists need to examine more than 100 diagnostic metrics and associated graphics for each candidate exoplanet-transit-like signal to classify it into one of the three classes. Considering that the NASA Explorer Program's TESS mission and ESA's PLATO mission survey even a larger area of space, the classification of their transit-like signals is more time-consuming for human agents and a bottleneck to successfully construct the new catalogues in a timely manner. This encourages building automatic classification tools that can quickly and reliably classify the new signal data from these missions. The standard tool for building automatic classification systems is the supervised machine learning that requires a large set of highly accurate labeled examples in order to build an effective classifier. This requirement cannot be easily met for classifying transit-like signals because not only are existing labeled signals very limited, but also the current labels may not be reliable (because the labeling process is a subjective task). Our experiments with using different supervised classifiers to categorize transit-like signals verifies that the labeled signals are not rich enough to provide the classifier with enough power to generalize well beyond the observed cases (e.g. to unseen or test signals). That motivated us to utilize a new category of learning techniques, so-called semi-supervised learning, that combines the label information from the costly labeled signals, and distribution information from the cheaply available unlabeled signals in order to construct more effective classifiers. Our study on the Kepler Mission data shows that semi-supervised learning can significantly improve the result of multiple base classifiers (e.g. Support Vector Machines, AdaBoost, and Decision Tree) and is a good technique for automatic classification of exoplanet-transit-like signal.
G. Privon*; R. Herrero-Illana; A. Evans; K. Iwasawa; M. Perez-Torres; L. Armus; T. Diaz-Santos; E. Murphy; S. Stierwalt; S. Aalto; J. Mazzarella; L. Barcos-MuÃ; J. Borish; H. Inami; D. Kim; E. Treister; J. Surace; S. Lord; J. Conway; D. Frayer; A. Alberdi
Excitation Mechanisms for HCN (1–0) and HCO+ (1–0) in Galaxies from the Great Observatories All-sky LIRG Survey
Abstract Body: We will present new IRAM 30m observations of the HCN (1–0) and HCO+ (1–0) emission in a sample of Luminous and Ultraluminous Infrared Galaxies from the Great Observatories All-sky LIRG Survey. These new measurements are compared with mid-infrared AGN diagnostics to ascertain if enhanced HCN emission (relative to HCO+) correlates with increased AGN dominance. I will also compare consider the global relationships of these dense gas tracers with the infrared luminosity, to investigate the relationship between the HCN and HCO+ luminosities and the ongoing star formation. These comparisons suggest the HCN and HCO+ emission depend on both density and radiative effects (XDRs, mid-infrared pumping), obstructing a simple interpretation of the HCN/HCO+ ratio.