SETI Institute Scientists Head to the 227th meeting of the American Astronomical Society
The following is a list of posters and presentations by SETI Institute scientists attending the AAS meeting in Kissimmee, Florida, January 4-8, 2016.
1. J. Christiansen*; B. Clarke; C. J. Burke; S. Seader; J. M. Jenkins; J. D. Twicken; J. C. Smith; N. M. Batalha; M. R. Haas; S. E. Thompson; J. Campbell; J. Catanzarite
NASA Exoplanet Science Institute; SETI Institute; NASA Ames Research Center
Where Are All The Earth Twins Hiding? Measuring the Detection Efficiency of the Kepler Pipeline
We present the results of the first measurement of the Kepler pipeline detection efficiency that explores the full Kepler observation baseline, the full field of view, and uses the same code as that used to generate the planet candidate catalogue. The full table of nearly 160,000 injections, including their parameters and recovery status, is publicly available at the NASA Exoplanet Archive; we demonstrate a worked example starting from the table to illustrate use cases. We find that there are significant differences in detection efficiency across transit period (lower efficiency at longer periods than expected from pure signal-to-noise estimates) and across stellar type (lower efficiency for giant stars than expected). The former highlights the difficulty in detecting Earth-like planets in the Kepler data; the latter the importance of starting from a well-characterised stellar sample.
2. K. L. Karnes*; T. Kahre; J. C. Smith; D. A. Caldwell
Colgate University; SETI Institute/NASA Ames Research Center; University of Oklahoma
The Detection of Kepler K2 Campaigns 3 and 4 Planet Candidates
The K2 mission, developed to repurpose the Kepler spacecraft, is providing light curve data quality that exceeds initial K2 design specifications despite the failure of two reaction wheels. We discuss the modification of the five modules of the Kepler Science Processing Pipeline for K2 data planet transit detection. The modified pipeline was applied to K2 Campaign 3 and 4 data sets. Despite the inherently noiser K2 light curves, which are mostly due to spacecraft roll motion, the modified pipeline proved to be effective at detecting transiting planets in K2 light curves. From the Campaign 3 data set, which consists of 70 days of observations of 16,375 targets, we present a catalog of 41 planet candidates in 33 systems. We calculate stellar radii for these 33 stars to obtain initial planet parameters. The catalog contains many systems of interest, including 26 planets with radii less than four Earth radii and two three-planet systems.
3. T. Kahre*; K. L. Karnes; D. A. Caldwell; J. C. Smith
University of Oklahoma; Colgate University; SETI Institute; SETI Institute
A Systematic Search for Exoplanet Candidates in K2 Data
We present a catalog of 41 promising exoplanet candidates in 33 stellar systems from the K2 Campaign 3 data. The K2 Mission was developed upon the mechanical failure of the second of four reaction wheels, as the Kepler Spacecraft could not continue the original Kepler Mission. The Kepler Mission was a 4-year mission designed to determine the prevalence of exoplanets in our galaxy, and the configuration and diversity of those planetary systems discovered. The K2 Mission has a similar goal, though the spacecraft now points at fields along the ecliptic in ~75 day campaigns (Howell et al. 2014). Although the light curves in K2 data are noisier and have significant motion-induced systematics, it has been shown that there is success in finding exoplanets and exoplanet candidates (Foreman-Mackey et al. 2015; Montet et al. 2015). Utilizing the Transiting Planet Search and Data Validation from the KeplerProcessing Pipeline, we systematically search K2 Campaign 3 for potential exoplanet candidates. Setting a 7.1s maximum folded statistic threshold minimum for a minimum of three transit events, we define our initial candidate list. Our list is further narrowed by the results from Data Validation, as it allows us to statistically identify false positives, such as eclipsing binaries or uncorrected roll-drift, in our sample. We further draw parallels between our results and other transit-searching pipeline results published for Campaign 3.
4. A. Chontos*; B. Macintosh; E. L. Nielsen
Department of Physics, State University of New York at Albany; Kavli Institute for Particle Astrophysics and Cosmology, Stanford University; SETI Institute, Carl Sagan Center
Simulations of Detectability of Extrasolar Planets by a Joint Doppler and WFIRST-AFTA Coronagraph Survey
A long-term goal for the astronomical community is to image and characterize an Earth-like planet. The WFIRST-AFTA space mission will make advancements towards this goal. WFIRST will include a coronagraphic instrument to discover and characterize new exoplanets and to better characterize already known exoplanets. We present results of simulations using a Doppler survey to find lower mass planets as possible targets for WFIRST. For simulations, simplified completeness estimates (Howard & Fulton 2014) are used to test the sensitivity of a prospective Doppler campaign. We use data from the HARPS spectrograph to determine exposure times needed to achieve 1 m/s uncertainty. Stellar jitter was randomly sampled from a uniform distribution based on spectral type, treating OBA-type, FGK-type, and M-type stars separately. For survey parameters, we use campaign parameters from the WIYN telescope, assuming 10 hours per night at 100 nights per year over 6 years. In any one simulation, we find roughly 45-50 new planets that are potentially observable by WFIRST. By limiting our targets to FGKM type stars within 10 parsecs, we expect one of those planets to be less than 10 M.
5. S. C. Blunt*; E. Nielsen; F. Marchis; R. De Rosa; Q. Konopacky; B. Macintosh; J. Wang; C. Marois; L. Pueyo; J. Rameau; J. R. Graham
Brown University; SETI Institute; Stanford University; University of California at Berkeley; University of California at San Diego; National Research Council of Canada Herzberg; University of Victoria; Space Telescope Science Institute; Universite de Montreal
Characterizing Exoplanet Motions Using Random Orbit Generation for the Gemini Planet Imager Exoplanet Survey
Next generation planet-finders like the Gemini Planet Imager (GPI) allow for direct imaging of exoplanets that are close enough to their host stars to undergo detectable orbital motion on monthly timescales, creating a need for methods that rapidly characterize newly discovered planets using short astrometric baselines. We present a computationally efficient Monte Carlo method that fits randomly generated orbital parameters to astrometry of directly imaged exoplanets from a fraction of an orbit. This code quickly and efficiently produces distributions of plausible orbital parameters, while a traditional Markov-Chain Monte Carlo algorithm would take much longer to converge given the same inputs (future work will directly compare the computational efficiencies and outputs of both algorithms).This technique allows us to predict the future motion of a planet by randomly generating plausible orbits that fit just a few epochs of astrometry, or even a single epoch. We first applied this method to predicting the future position of 51 Eri b, a giant exoplanet discovered by GPIES, using astrometry with only a 1-month baseline. Subsequent observations of 51 Eri b after seven months found the planet at the peak of the probability distributions predicting future motion. We demonstrate how this method can be applied to GPIES and the future WFIRST-AFTA space mission, from distinguishing bound planets from background objects to constraining orbital parameters given data from only a few observational epochs after discovery. This material is based on work supported by the National Science Foundation REU Program under Grant No. AST-1359346.
6. M. C. Turnbull*; R. C. Kotulla; J. S. Gallagher; A. Merrelli; T. L'Ecuyer; G. Fu; R. Hu
SETI Institute; University of Wisconsin; JPL
WFIRST Exoplanet Imaging: Can Broadband Colors Efficiently Descriminate Planets from the Background?
As part of the WFIRST Preparatory Science program, we have begun exploring the broadband color combinations for WFIRST that will most efficiently (1) descriminate planets from background sources in a single image and (2) shed some light on the nature of those planets. This is a first look at the color-color space, and color-magnitude space, occupied by planets orbiting nearby K-F main sequence stars. We explore (1) Solar System analog planets, (2) a variety of Earths/Super-Earths having optically thin or partially cloudy Earth-like atmospheres over desert/forest/ocean/icey surfaces, and (3) mini-Neptunes through Jupiter-mass planets at a range of temperatures where they would potentially be detectable to WFIRST. These colors are compared to the expected Galactic and extragalactic background sources for the Galactic coordinates of high priority targets. We offer some preliminary conclusions about the expected background contamination in these fields and how well color information can be used to mitigate that threat to WFIRST's exoplanet science.
7. J. Rho*; J. Hewitt; W. T. Reach; J. H. Bieging; M. Andersen; R. Güsten
SETI Institute and NASA Ames Research Center; NASA Goddard Space Flight Center; USRA/SOFIA; Univ. of Arizona; Gemini Observatory; Max Planck Institut fur Radioastronomie
Shocked Gas from the supernova remnant G357.7+0.3
We present detection of hydrogen molecular hydrogen (H2) in mid-infrared using the Spitzer IRS. The supernova remnant (SNR) G357.7+0.3 is one of relatively unknown and under-studied SNRs. We performed an IRS spectral mapping centered on the northwestern shell of G357.7+0.3. The observations covered an area of 75arcsec x 60arcsec with short-low (SL) and 170arcsec x 55arcsec with long-low (LL). All rotational H2 lines within the IRS wavelength range are detected except S(6) line. Interestingly, G357.7+0.3 shows lack of ionic lines compared with those in other SNRs observed. Only ionic line detected is [Si II] at 34.8micron. The detection of H2 line is an evidence that G357.7+0.3 is interacting with dense molecular clouds. This is the first evidence showing that G357.7+0.3 is an interacting SNR with clouds. We generated a H2 excitation diagram. A two-temperature fit yields a low temperature of 197 K with a column density 2.3E21/cm2 and and a high temperature of 663 K with a column density of 2.7E19/cm2. We preformed high-J CO and OH observations with The German REceiver for Astronomy at Terahertz Frequencies (GREAT) on board of Stratospheric Observatory for Infrared Astronomy (SOFIA), but no lines are detected. We provide the upper limits of the lines. We also present millimeter observations of the SNR. The observations were made with the Arizona-MPIfR Heinrich Hertz Submillimeter Telescope (HHT), Arizona 12 Meter Telescope, and Atacama Pathfinder Experiment (APEX) Telescope. We discuss physical conditions of shocked gas in G357.7+0.3.
8. M. Zimmerman*; S. E. Thompson; K. Hambleton; J. Fuller; A. Shporer; H. T. Isaacson; A. Howard; . Kurtz
Juniata College; SETI Institute; University of Central Lancashire; Kalvi Institute for Theoretical Physics; NASA’s Jet Propulsion Laboratory; University of California Berkley; University of Hawaii
Pseudosynchronization of Heartbeat Stars
A type of eccentric binary star that undergoes extreme dynamic tidal forces, known as Heartbeat stars, were discovered by the Kepler Mission. As the two stars pass through periastron, the tidal distortion causes unique brightness variations. Short period, eccentric binary stars, like these, are theorized to pseudosynchronize, or reach a rotational frequency that matches the weighted average orbital angular velocity of the system. This pseudosynchronous rate, as predicted by Hut (1981), depends on the binary's orbital period and eccentricity. We tested whether sixteen heartbeat stars have pseudosynchronized. We measure the rotation rate from obvious spot signatures in the light curve. We measure the eccentricity by fitting the light curve using PHOEBE and are actively carrying out a radial velocity monitoring program with Keck/HIRES in order to improve these orbital parameters. Our initial results show that while most heartbeat stars appear to have pseudosynchronized we find stars with rotation frequencies both longer and shorter than this rate. We thank the SETI Institute REU program, the NSF, and the Kepler Guest Observer Program for making this work possible.
9. R. Diaz*; G. Harp
California State Polytechnic University, Pomona; SETI Institute
Time-Resolved Spectral Analysis of Blazar 0716+714
As electromagnetic (EM) waves from sources such as blazars travel through the intergalactic medium (IGM), they are slowed by electrons; a phenomenon called dispersion delay . We study the propagation effects in emissions of EM waves from blazar source BL 0716+714 by estimating the average electron density, or dispersion measure (DM), of the IGM on a line of sight to the blazar. Measuring the variations in these effects with time allow us to understand the properties of the intervening material. Toward this goal we analyzed months of archived observations of BL 0716+714 taken by the Allen Telescope Array (ATA). The ATA’s correlator produces cross-power vs. frequency spectra for every baseline (distance between a pair of antennas) in ten-second intervals. To reduce this immense load of data we used a technique based on interferometry called bispectrum, which does not depend on complicated array calibration and simplifies our work. The bispectrum multiplies baselines, three at a time, so that they form a closed loop, then the cube root of spectra are averaged . This technique is independent of phase errors associated with any individual antenna and has a better SNR ratio than simply taking the average of all the baselines. We developed a numerical analysis program that takes in archived blazar files containing correlation data, computes the bispectrum, and outputs FITS images for each day of observations. The results show that our observations do not have sufficient sensitivity to reveal blazar variations in the frequency ranges that were studied. It is suggested that future observations at higher frequencies and/or with another telescope having greater sensitivity would reveal the time/frequency dependence of emission structure that would allow measurements of electron content. This work shows that but bispectrum is a useful tool for rapid characterization of interferometer data that does not require interferometer caclibration which could introduce artifacts into radio light curvesLaw C.J. and Bower G.C. (2012) Astrophysical Journal, 749:143 Rani B. et al. (2013) A&A, ms, 1-25.
10. R. Sankrit*; M. L. Leal-Ferreira; I. Aleman; S. W. Colgan; J. P. Simpson; X. Tielens; Y. G. Tsamis
SOFIA Science Center/USRA; Leiden University; NASA/Ames; Seti Institute; Nature Publishing Group
SOFIA/FORCAST Spectroscopy of NGC 7009, the Saturn Nebula
We present spatially resolved mid-IR spectra of the well-studied Planetary Nebula (PN) NGC 7009 obtained with the FORCAST instrument on board the Stratospheric Observatory for Infrared Astronomy (SOFIA). NGC 7009 has a relatively high "abundance discrepancy factor" - the heavy element abundances derived from optical recombination lines (ORLs) are higher by a factor of about 5 than abundances derived from collisionally excited lines (CELs). One hypothesis to resolve this discrepancy is that two kinds of regions with distinct properties are responsible for the abundance measurements from ORLs and CELs. Lines from [OIV], [SIII], [SIV] and [ArIII] are detected in the FORCAST spectra, which cover the wavelength ranges 8.7--13.9 and 17.7--27.6 microns with moderate spectral resolution (R~100). We explore the abundance variations with radial distance from the center of the nebula and their possible correlations with the abundance discrepancy factor. Starting with our observations and results on NGC 7009 as an example, we present a survey of the capabilities of SOFIA, and describe its potential in the field of infra-red studies of Galactic PNe.
11. G. Fu*; M. C. Turnbull; J. S. Gallagher; R. C. Kotulla; A. Merrelli; T. L'Ecuyer; R. Hu
University of Wisconsin - Madison; SETI Institute; JPL
Imaging exoplanets with the WFIRST Coronagraph: A background check of high priority targets
The WFIRST coronagraph is envisioned to achieve a limiting contrast for exoplanet detection of 10e-9. This revolutionary mission will enable the direct detection of known and newly discovered exoplanets amongst the nearest stars, from super-Earths to giants. However, at this contrast the coronagraph will essentially see a Hubble Ultra Deep Field (HUDF) in every image. For targets near the Galactic Plane on the sky, distant stars with varying levels of extinction and reddening will dominate the background. Away from the plane, we then expect extragalactic sources to dominate. What impact will these background sources have on the WFIRST exoplanet imaging program? How can we efficiently distinguish background sources from exoplanet targets in a single image? To have a comprehensive understanding of the distribution of background sources across the sky, we have used the HUDF to model extragalactic faint sources, and “Trilegal” simulations to model galactic background sources. Through some preliminary color and point source analysis, we offer a statistical estimation of expected background contamination and the probability of false positive background sources. In this poster we show plots relating number of extragalactic sources versus magnitude in HUDF and “Trilegal” simulation. We present a table of high priority WFIRST exoplanet imaging targets, with an assessment of the “background threat” due to background stars, galaxies, and binary companions.
12. G. Harp*
Five Years of SETI with the Allen Telescope Array: Lessons Learned
We discuss recent observations at the Allen Telescope Array (ATA) supporting a wide ranging Search for Extraterrestrial Intelligence (SETI). The ATA supports observations over the frequency range 1-10 GHz with three simultaneous phased array beams used in an anticoincidence detector for false positive rejection. Here we summarize observational results over the years 2011-2015 covering multiple campaigns of exoplanet stars, the galactic plane, infrared excess targets, etc. Approximately 2 x 10 signals were identified and classified over more than 5000 hours of observation. From these results we consider various approaches to the rapid identification of human generated interference in the process of the search for a signal with origins outside the radius of the Moon’s orbit. We conclude that the multi-beam technique is superb tool for answering the very difficult question of the direction of origin of signals. Data-based simulations of future instruments with more than 3 beams are compared.
What is the AAS?
The American Astronomical Society (AAS), established in 1899 and based in Washington, DC, is the major organization of professional astronomers in North America. Its membership of about 7,000 individuals also includes physicists, mathematicians, geologists, engineers, and others whose research and educational interests lie within the broad spectrum of subjects comprising contemporary astronomy. The mission of the AAS is to enhance and share humanity’s scientific understanding of the universe.
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The K2 mission, developed to repurpose the Kepler spacecraft, is providing light curve data quality that exceeds initial K2 design specifications despite the failure of two reaction wheels.
A long-term goal for the astronomical community is to image and characterize an Earth-like planet. The WFIRST-AFTA space mission will make advancements towards this goal.