144 research outputs found
Planet Hunters: Assessing the Kepler Inventory of Short Period Planets
We present the results from a search of data from the first 33.5 days of the
Kepler science mission (Quarter 1) for exoplanet transits by the Planet Hunters
citizen science project. Planet Hunters enlists members of the general public
to visually identify transits in the publicly released Kepler light curves via
the World Wide Web. Over 24,000 volunteers reviewed the Kepler Quarter 1 data
set. We examine the abundance of \geq 2 R\oplus planets on short period (< 15
days) orbits based on Planet Hunters detections. We present these results along
with an analysis of the detection efficiency of human classifiers to identify
planetary transits including a comparison to the Kepler inventory of planet
candidates. Although performance drops rapidly for smaller radii, \geq 4
R\oplus Planet Hunters \geq 85% efficient at identifying transit signals for
planets with periods less than 15 days for the Kepler sample of target stars.
Our high efficiency rate for simulated transits along with recovery of the
majority of Kepler \geq 4 R\oplus planets suggest suggests the Kepler inventory
of \geq 4 R\oplus short period planets is nearly complete.Comment: 41 pages,13 figures, 8 tables, accepted to Ap
Planet Hunters: New Kepler planet candidates from analysis of quarter 2
We present new planet candidates identified in NASA Kepler quarter two public
release data by volunteers engaged in the Planet Hunters citizen science
project. The two candidates presented here survive checks for false-positives,
including examination of the pixel offset to constrain the possibility of a
background eclipsing binary. The orbital periods of the planet candidates are
97.46 days (KIC 4552729) and 284.03 (KIC 10005758) days and the modeled planet
radii are 5.3 and 3.8 R_Earth. The latter star has an additional known planet
candidate with a radius of 5.05 R_Earth and a period of 134.49 which was
detected by the Kepler pipeline. The discovery of these candidates illustrates
the value of massively distributed volunteer review of the Kepler database to
recover candidates which were otherwise uncatalogued.Comment: Accepted to A
The Visual Orbit of the 1.1-day Spectroscopic Binary \sigma^2 Coronae Borealis from Interferometry at the CHARA Array
We present an updated spectroscopic orbit and a new visual orbit for the
double-lined spectroscopic binary \sigma^2 Coronae Borealis based on radial
velocity measurements at the Oak Ridge Observatory in Harvard, Massachusetts
and interferometric visibility measurements at the CHARA Array on Mount Wilson.
\sigma^2 CrB is composed of two Sun-like stars of roughly equal mass in a
circularized orbit with a period of 1.14 days. The long baselines of the CHARA
Array have allowed us to resolve the visual orbit for this pair, the shortest
period binary yet resolved interferometrically, enabling us to determine
component masses of 1.137 \pm 0.037 M_sun and 1.090 \pm 0.036 M_sun. We have
also estimated absolute V-band magnitudes of MV (primary) = 4.35 \pm 0.02 and
MV(secondary) = 4.74 \pm 0.02. A comparison with stellar evolution models
indicates a relatively young age of 1-3 Gyr, consistent with the high Li
abundance measured previously. This pair is the central component of a
quintuple system, along with another similar-mass star, \sigma^1 CrB, in a ~
730-year visual orbit, and a distant M-dwarf binary, \sigma CrB C, at a
projected separation of ~ 10 arcmin. We also present differential proper motion
evidence to show that components C & D (ADS 9979C & D) listed for this system
in the Washington Double Star Catalog are optical alignments that are not
gravitationally bound to the \sigma CrB system.Comment: 40 pages, 14 figures. Accepted by Ap
Characterizing K2 planet discoveries : a super-Earth transiting the bright K dwarf HIP 116454
We report the first planet discovery from the two-wheeled Kepler (K2) mission: HIP 116454 b. The host star HIP 116454 is a bright (V = 10.1, K = 8.0) K1 dwarf with high proper motion and a parallax-based distance of 55.2 ± 5.4 pc. Based on high-resolution optical spectroscopy, we find that the host star is metal-poor with [Fe/H] =–0.16 ± 0.08 and has a radius R = 0.716 ± 0.024 R ☉ and mass M = 0.775 ± 0.027 M ☉. The star was observed by the Kepler spacecraft during its Two-Wheeled Concept Engineering Test in 2014 February. During the 9 days of observations, K2 observed a single transit event. Using a new K2 photometric analysis technique, we are able to correct small telescope drifts and recover the observed transit at high confidence, corresponding to a planetary radius of pR = 2.53 ± 0.18 R ⊕. Radial velocity observations with the HARPS-N spectrograph reveal a 11.82 ± 1.33 M ⊕ planet in a 9.1 day orbit, consistent with the transit depth, duration, and ephemeris. Follow-up photometric measurements from the MOST satellite confirm the transit observed in the K2 photometry and provide a refined ephemeris, making HIP 116454 b amenable for future follow-up observations of this latest addition to the growing population of transiting super-Earths around nearby, bright stars.Publisher PDFPeer reviewe
Planetary Candidates Observed by Kepler VI: Planet Sample from Q1-Q16 (47 Months)
\We present the sixth catalog of Kepler candidate planets based on nearly 4
years of high precision photometry. This catalog builds on the legacy of
previous catalogs released by the Kepler project and includes 1493 new Kepler
Objects of Interest (KOIs) of which 554 are planet candidates, and 131 of these
candidates have best fit radii <1.5 R_earth. This brings the total number of
KOIs and planet candidates to 7305 and 4173 respectively. We suspect that many
of these new candidates at the low signal-to-noise limit may be false alarms
created by instrumental noise, and discuss our efforts to identify such
objects. We re-evaluate all previously published KOIs with orbital periods of
>50 days to provide a consistently vetted sample that can be used to improve
planet occurrence rate calculations. We discuss the performance of our planet
detection algorithms, and the consistency of our vetting products. The full
catalog is publicly available at the NASA Exoplanet Archive.Comment: 18 pages, to be published in the Astrophysical Journal Supplement
Serie
Masses, radii, and orbits of small Kepler planets : The transition from gaseous to rocky planets
We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm-3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than 2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).Peer reviewedFinal Accepted Versio
Crop Updates 2000 Cereals - part 3
This session covers eighteen papers from different authors:
BARLEY AND OAT AGRONOMY
1. Unicorn barley must meet malting specifications to be a viable option, Roslyn Jettnerand Blakely Paynter, Agriculture Western Australia
2. Optimum oat seed rates, Glenn McDonald, Agriculture Western Australia
3. Production and Quality of export Oaten Hay (1998 and 1989), Pierre Fievez, Pierre Fievez and Associates
FROST
4. Climatology of Frost in Southern Western Australia, Ian Foster, Agriculture Western Australia
5. Flowering calculator, David Tennant, Agriculture Western Australia
6. Some options for managing the risk of frost damage, Wal Anderson, Agriculture Western Australia
PASTURE
7. TIMERITE® Control of redlegged earth mite in south western Australia with a spring spray to pastures, James Ridsdill-Smith and Celia Pavri, CSIRO Entomology, University of Western Australia
8. The pattern of seed softening in subterranean clover in relation to presicted false break risk, Ross Chapman and Senthold Asseng, CSIRO Plant Industry, Centre for Mediterranean Agricultural Research
9. Charano serradella – a viable option for 1:1 cropping, Steve Carr and Brad Nutt IAMA Agri-Services Western Australia and Centre for Legumes in Mediterranean Agriculture, University of Western Australia
10. Alfalfa mosaic virus in alternative annual pasture and forage legumes, Lindrea Latham and Roger Jones, Crop Improvement Institute, Agriculture Western Australia and Centre for Legumes in Mediterranean Agriculture, University of Western Australia
11. Pasture mixture performs better than single-species-based pasture – 1999, Anyou Liu, Clinton Revell and David Ferris, Centre for Cropping Systems, Agriculture Western Australia
12. Better pasture management improves performance of following crops – 1999, Anyou Liu, Clinton Revell and David Ferris, Centre for Cropping Systems, Agriculture Western Australia
13. Lucerne Benefits Crop Production, Roy Latta1, Lisa-Jane Blacklow2, Chris Matthews1 1Agriculture Western Australia 2University of Western Australia
14. Does size count? Determining optimum release number of red apion for biocontrol of doublegee, Tim Woodburn and Paul Yeoh, CSIRO Entomology/CRC Weed Management Systems, Perth
15. Herbicide tolerance of some new cultivars of annual pasture legumes, Clinton Revell and Ian Rose, Centre for Cropping Systems, Agriculture Western Australia
16. Lucerne – crop rotations in the Esperance region, Anita Lyons, Roy Latta and Chris Matthews,Agriculture Western Australia
PRECISION AGRICULTURE
17. Assessing the results of on-farm experiments using yield monitors, Simon Cook and Matthew Adams, CSIRO Land and Water
18. Achiever: A GIS based achievable yield and fertiliser recommendation system for precision agriculture, Robert J. Corner, Matthew L. Adams, Precision Agriculture Research Group CSIRO Land and Wate
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