Globular Clusters: Absolute Proper Motions and Galactic Orbits

NASA Astrophysics Data System (ADS)

Chemel, A. A.; Glushkova, E. V.; Dambis, A. K.; Rastorguev, A. S.; Yalyalieva, L. N.; Klinichev, A. D.

2018-04-01

We cross-match objects from several different astronomical catalogs to determine the absolute proper motions of stars within the 30-arcmin radius fields of 115 Milky-Way globular clusters with the accuracy of 1-2 mas yr-1. The proper motions are based on positional data recovered from the USNO-B1, 2MASS, URAT1, ALLWISE, UCAC5, and Gaia DR1 surveys with up to ten positions spanning an epoch difference of up to about 65 years, and reduced to Gaia DR1 TGAS frame using UCAC5 as the reference catalog. Cluster members are photometrically identified by selecting horizontal- and red-giant branch stars on color-magnitude diagrams, and the mean absolute proper motions of the clusters with a typical formal error of about 0.4 mas yr-1 are computed by averaging the proper motions of selected members. The inferred absolute proper motions of clusters are combined with available radial-velocity data and heliocentric distance estimates to compute the cluster orbits in terms of the Galactic potential models based on Miyamoto and Nagai disk, Hernquist spheroid, and modified isothermal dark-matter halo (axisymmetric model without a bar) and the same model + rotating Ferre's bar (non-axisymmetric). Five distant clusters have higher-than-escape velocities, most likely due to large errors of computed transversal velocities, whereas the computed orbits of all other clusters remain bound to the Galaxy. Unlike previously published results, we find the bar to affect substantially the orbits of most of the clusters, even those at large Galactocentric distances, bringing appreciable chaotization, especially in the portions of the orbits close to the Galactic center, and stretching out the orbits of some of the thick-disk clusters.

VizieR Online Data Catalog: The VLBA Extragalactic Proper Motion Catalog (Truebenbach+, 2017)

NASA Astrophysics Data System (ADS)

Truebenbach, A. E.; Darling, J.

2017-11-01

We created our catalog of extragalactic radio proper motions using the 2017a Goddard VLBI global solution. The 2017a solution is computed from more than 30 years of dual-band VLBI observations --1979 August 3 to 2017 March 27. We also observed 28 objects with either no redshift or a "questionable" Optical Characteristic of Astrometric Radio Sources (OCARS; Malkin 2016ARep...60..996M) redshift at the Apache Point Observatory (APO) 3.5m telescope and/or at Gemini North. We conducted observations on the 3.5m telescope at Apache Point Observatory with the Dual Imaging Spectrograph (DIS) from 2015 April 18 to 2016 June 30. We chose two objects for additional observations with the Gemini Multi-Object Spectrograph-North (GMOS-N) at Gemini North Observatory. 2021+317 was observed on 2016 June 26 and 28, while 0420+417 was observed on 2016 November 8 and 26. We also observed 42 radio sources with the Very Long Baseline Array (VLBA) in the X-band (3.6cm/8.3GHz). Our targets had all been previously observed by VLBI. Our VLBA observations were conducted in two campaigns from 2015 September to 2016 January and 2016 October to November. The final extragalactic proper motion catalog (created primarily from archival Goddard VLBI data, with redshifts obtained from OCARS) contains 713 proper motions with average uncertainties of 24μas/yr. (5 data files).

An All-Sky Search for Wide Binaries in the SUPERBLINK Proper Motion Catalog

NASA Astrophysics Data System (ADS)

Hartman, Zachary; Lepine, Sebastien

2017-01-01

We present initial results from an all-sky search for Common Proper Motion (CPM) binaries in the SUPERBLINK all-sky proper motion catalog of 2.8 million stars with proper motions greater than 40 mas/yr, which has been recently enhanced with data from the GAIA mission. We initially search the SUPERBLINK catalog for pairs of stars with angular separations up to 1 degree and proper motion difference less than 40 mas/yr. In order to determine which of these pairs are real binaries, we develop a Bayesian analysis to calculate probabilities of true companionship based on a combination of proper motion magnitude, angular separation, and proper motion differences. The analysis reveals that the SUPERBLINK catalog most likely contains ~40,000 genuine common proper motion binaries. We provide initial estimates of the distances and projected physical separations of these wide binaries.

Searching for High Proper Motion Sources Towards the Galactic Center using Convolution Neural Networks

NASA Astrophysics Data System (ADS)

Giongo Fernandes, Alexandre; Benjamin, Robert A.; Babler, Brian

2018-01-01

Two sets of infrared images of the Galactic Center region (|L|< 1 degree and |B| < 0.75 degrees) taken by the Spitzer Space Telescope in IRAC 3.6 micron and 4.5 micron bands are searched for high proper motion objects (> 100 mas/year). The two image sets come from GALCEN observations in 2005 and GLIMPSE proper observations in 2015 with matched observation modes. We use three different methods to search for these objects in extremely crowded fields: (1) comparing matched point source lists, (2) crowd sourcing by several college introductory astronomy classes in the state of Wisconsin (700 volunteers), and (3) convolutional neural networks trained using objects from the previous two methods. Before our search six high proper objects were known, four of which were found by the VVV near-infrared Galactic plane survey. We compare and describe our methods for this search, and present a preliminary catalog of high proper motions objects.

RELATIVE PROPER MOTIONS IN THE RHO OPHIUCHI CLUSTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilking, Bruce A.; Sullivan, Timothy; Vrba, Frederick J., E-mail: bwilking@umsl.edu, E-mail: tsullivan@umsl.edu, E-mail: fjv@nofs.navy.mil

2015-12-10

Near-infrared images optimized for astrometry have been obtained for four fields in the high-density L 1688 cloud core over a 12 year period. The targeted regions include deeply embedded young stellar objects (YSOs) and very low luminosity objects too faint and/or heavily veiled for spectroscopy. Relative proper motions in R.A. and decl. were computed for 111 sources and again for a subset of 65 YSOs, resulting in a mean proper motion of (0,0) for each field. Assuming each field has the same mean proper motion, YSOs in the four fields were combined to yield estimates of the velocity dispersions inmore » R.A. and decl. that are consistent with 1.0 km s{sup −1}. These values appear to be independent of the evolutionary state of the YSOs. The observed velocity dispersions are consistent with the dispersion in radial velocity derived for optically visible YSOs at the periphery of the cloud core and are consistent with virial equilibrium. The higher velocity dispersion of the YSOs in the plane of the sky relative to that of dense cores may be a consequence of stellar encounters due to dense cores and filaments fragmenting to form small groups of stars or the global collapse of the L 1688 cloud core. An analysis of the differential magnitudes of objects over the 12 year baseline has not only confirmed the near-infrared variability for 29 YSOs established by prior studies, but has also identified 18 new variability candidates. Four of these have not been previously identified as YSOs and may be newly identified cluster members.« less

Fixing the reference frame for PPMXL proper motions using extragalactic sources

DOE PAGES

Grabowski, Kathleen; Carlin, Jeffrey L.; Newberg, Heidi Jo; ...

2015-05-27

In this study, we quantify and correct systematic errors in PPMXL proper motions using extragalactic sources from the first two LAMOST data releases and the Vèron-Cetty & Vèron Catalog of Quasars. Although the majority of the sources are from the Vèron catalog, LAMOST makes important contributions in regions that are not well-sampled by previous catalogs, particularly at low Galactic latitudes and in the south Galactic cap. We show that quasars in PPMXL have measurable and significant proper motions, which reflect the systematic zero-point offsets present in the catalog. We confirm the global proper motion shifts seen by Wu et al.,more » and additionally find smaller-scale fluctuations of the QSO-derived corrections to an absolute frame. Finally, we average the proper motions of 158 106 extragalactic objects in bins of 3° × 3° and present a table of proper motion corrections.« less

Chemically Dissected Rotation Curves of the Galactic Bulge from Main-sequence Proper Motions

NASA Astrophysics Data System (ADS)

Clarkson, William I.; Calamida, Annalisa; Sahu, Kailash C.; Brown, Thomas M.; Gennaro, Mario; Avila, Roberto J.; Valenti, Jeff; Debattista, Victor P.; Rich, R. Michael; Minniti, Dante; Zoccali, Manuela; Aufdemberge, Emily R.

2018-05-01

We report results from an exploratory study implementing a new probe of Galactic evolution using archival Hubble Space Telescope imaging observations. Precise proper motions are combined with photometric relative metallicity and temperature indices, to produce the proper-motion rotation curves of the Galactic bulge separately for metal-poor and metal-rich main-sequence samples. This provides a “pencil-beam” complement to large-scale wide-field surveys, which to date have focused on the more traditional bright giant branch tracers. We find strong evidence that the Galactic bulge rotation curves drawn from “metal-rich” and “metal-poor” samples are indeed discrepant. The “metal-rich” sample shows greater rotation amplitude and a steeper gradient against line-of-sight distance, as well as possibly a stronger central concentration along the line of sight. This may represent a new detection of differing orbital anisotropy between metal-rich and metal-poor bulge objects. We also investigate selection effects that would be implied for the longitudinal proper-motion cut often used to isolate a “pure-bulge” sample. Extensive investigation of synthetic stellar populations suggests that instrumental and observational artifacts are unlikely to account for the observed rotation curve differences. Thus, proper-motion-based rotation curves can be used to probe chemodynamical correlations for main-sequence tracer stars, which are orders of magnitude more numerous in the Galactic bulge than the bright giant branch tracers. We discuss briefly the prospect of using this new tool to constrain detailed models of Galactic formation and evolution. Based on observations made with the NASA/ESA Hubble Space Telescope and obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Absolute proper motion of IRAS 00259+5625 with VERA: Indication of superbubble expansion motion

NASA Astrophysics Data System (ADS)

Sakai, Nobuyuki; Sato, Mayumi; Motogi, Kazuhito; Nagayama, Takumi; Shibata, Katsunori M.; Kanaguchi, Masahiro; Honma, Mareki

2014-02-01

We present the first measurement of the absolute proper motions of IRAS 00259+5625 (CB3, LBN594) associated with the H I loop called the "NGC 281 superbubble" that extends from the Galactic plane over ˜ 300 pc toward decreasing galactic latitude. The proper motion components measured with VLBI Exploration of Radio Astrometry (VERA) are (μαcos δ, μδ) = (-2.48 ± 0.32, -2.85 ± 0.65) mas yr-1, converted into (μlcos b, μb) = (-2.72 ± 0.32, -2.62 ± 0.65) mas yr-1 in the Galactic coordinates. The measured proper motion perpendicular to the Galactic plane (μb) shows vertical motion away from the Galactic plane with a significance of about ˜ 4 σ. As for the source distance, the distance measured with VERA is marginal, 2.4^{+1.0}_{-0.6} kpc. Using the distance, an absolute vertical motion (vb) of -17.9 ± 12.2 km s-1 is determined with ˜ 1.5 σ significance. The tendency towards the large vertical motion is consistent with previous very long baseline interferometry (VLBI) results for NGC 281 associated with the same superbubble. Thus, our VLBI results indicate superbubble expansion motion whose origin is believed to be sequential supernova explosions.

The Optical Gravitational Lensing Experiment. The Catalog of Stellar Proper Motions toward the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Poleski, R.; Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.

2012-03-01

We present a catalog of over 6.2 million stars with measured proper motions. All these stars are observed in the direction of the Magellanic Clouds within the brightness range 12proper motions about 440 000 Galactic foreground stars can be selected. Because the proper motions are based on a few hundred epochs collected during eight years, their statistical uncertainties are below 0.5 mas/yr for stars brighter than I=18.5 mag. The parallaxes are derived with uncertainties down to 1.6 mas. For above 13 000 objects parallaxes are derived with significance above 3σ, which allows selecting about 270 white dwarfs (WDs). The search for common proper motion binaries among stars presented was performed resulting in over 500 candidate systems. The most interesting ones are candidate halo main sequence star-WD and WD-WD systems. The application of the catalog to the empirically bound Cepheid instability strip is also discussed.

Calculating Proper Motions in the WFCAM Science Archive for the UKIRT Infrared Deep Sky Surveys

NASA Astrophysics Data System (ADS)

Collins, R.; Hambly, N.

2012-09-01

The ninth data release from the UKIRT Infrared Deep Sky Surveys (hereafter UKIDSS DR9), represents five years worth of observations by its wide-field camera (WFCAM) and will be the first to include proper motion values in its source catalogues for the shallow, wide-area surveys; the Large Area Survey (LAS), Galactic Clusters Survey (GCS) and (ultimately) Galactic Plane Survey (GPS). We, the Wide Field Astronomy Unit (WFAU) at the University of Edinburgh who prepare these regular data releases in the WFCAM Science Archive (WSA), describe in this paper how we make optimal use of the individual detection catalogues from each observation to derive high-quality astrometric fits for the positions of each detection enabling us to calculate a proper motion solution across multiple epochs and passbands when constructing a merged source catalogue. We also describe how the proper motion solutions affect the calculation of the various attributes provided in the database source catalogue tables, what measures of data quality we provide and a demonstration of the results for observations of the Pleiades cluster.

General relativistic satellite astrometry. II. Modeling parallax and proper motion

NASA Astrophysics Data System (ADS)

de Felice, F.; Bucciarelli, B.; Lattanzi, M. G.; Vecchiato, A.

2001-07-01

The non-perturbative general relativistic approach to global astrometry introduced by de Felice et al. (\\cite{defetal}) is here extended to account for the star motions on the Schwarzschild celestial sphere. A new expression of the observables, i.e. angular distances among stars, is provided, which takes into account the effects of parallax and proper motions. This dynamical model is then tested on an end-to-end simulation of the global astrometry mission GAIA. The results confirm the findings of our earlier work, which applied to the case of a static (angular coordinates only) sphere. In particular, measurements of large arcs among stars (each measurement good to ~ 100 mu arcsec, as expected for V ~ 17 mag stars) repeated over an observing period comparable to the mission lifetime foreseen for GAIA, can be modeled to yield estimates of positions, parallaxes, and annual proper motions good to ~ 15 mu arcsec. This second round of experiments confirms, within the limitations of the simulation and the assumptions of the current relativistic model, that the space-born global astrometry initiated with Hipparcos can be pushed down to the 10-5 arcsec accuracy level proposed with the GAIA mission. Finally, the simplified case we have solved can be used as reference for testing the limiting behavior of more realistic models as they become available.

The UKIDSS-2MASS proper motion survey - I. Ultracool dwarfs from UKIDSS DR4

NASA Astrophysics Data System (ADS)

Deacon, N. R.; Hambly, N. C.; King, R. R.; McCaughrean, M. J.

2009-04-01

The UK Infrared Telescope Infrared Deep Sky Survey (UKIDSS) is the first of a new generation of infrared surveys. Here, we combine the data from two UKIDSS components, the Large Area Survey (LAS) and the Galactic Cluster Survey (GCS), with Two-Micron All-Sky Survey (2MASS) data to produce an infrared proper motion survey for low-mass stars and brown dwarfs. In total, we detect 267 low-mass stars and brown dwarfs with significant proper motions. We recover all 10 known single L dwarfs and the one known T dwarf above the 2MASS detection limit in our LAS survey area and identify eight additional new candidate L dwarfs. We also find one new candidate L dwarf in our GCS sample. Our sample also contains objects from 11 potential common proper motion binaries. Finally, we test our proper motions and find that while the LAS objects have proper motions consistent with absolute proper motions, the GCS stars may have proper motions which are significantly underestimated. This is possibly due to the bulk motion of some of the local astrometric reference stars used in the proper motion determination.

Radio Measurements of the Stellar Proper Motions in the Core of the Orion Nebula Cluster

NASA Astrophysics Data System (ADS)

Dzib, Sergio A.; Loinard, Laurent; Rodríguez, Luis F.; Gómez, Laura; Forbrich, Jan; Menten, Karl M.; Kounkel, Marina A.; Mioduszewski, Amy J.; Hartmann, Lee; Tobin, John J.; Rivera, Juana L.

2017-01-01

Using multi-epoch Very Large Array observations, covering a time baseline of 29.1 years, we have measured the proper motions of 88 young stars with compact radio emission in the core of the Orion Nebula Cluster (ONC) and the neighboring BN/KL region. Our work increases the number of young stars with measured proper motion at radio frequencies by a factor of 2.5 and enables us to perform a better statistical analysis of the kinematics of the region than was previously possible. Most stars (79 out of 88) have proper motions consistent with a Gaussian distribution centered on \\overline{{μ }α \\cos δ }=1.07+/- 0.09 mas yr-1, and \\overline{{μ }δ }=-0.84+/- 0.16 mas yr-1, with velocity dispersions of {σ }α =1.08+/- 0.07 mas yr-1, {σ }δ =1.27+/- 0.15 mas yr-1. We looked for organized movements of these stars but found no clear indication of radial expansion/contraction or rotation. The remaining nine stars in our sample show peculiar proper motions that differ from the mean proper motions of the ONC by more than 3σ. One of these stars, V 1326 Ori, could have been expelled from the Orion Trapezium 7000 years ago. Two could be related to the multi-stellar disintegration in the BN/KL region, in addition to the previously known sources BN, I and n. The others either have high uncertainties (so their anomalous proper motions are not firmly established) or could be foreground objects.

UCAC1: New Proper Motions for 27 Million Stars on the Southern Hemisphere

NASA Astrophysics Data System (ADS)

Zacharias, N.; Monet, S. Urban D. G.; Platais, I.; Wycoff, G. L.; Zacharias, M. I.; Rafferty, T. J.

The big impact of UCAC on galactic kinematics and dynamics studies will be outlined. The USNO CCD Astrograph (UCA) started an astrometric sky survey in February 1998 at Cerro Tololo, Chile. By January 2000 about 90% of the Southern Hemisphere has been observed and full sky coverage is expected by early 2003. In addition, calibration fields around extragalactic reference frame sources and selected open clusters are observed frequently. The UCAC project is a huge dedicated astrometric survey similar to the AGK2 and AGK3 projects but vastly exceeding those with respect to higher accuracy, limiting magnitude (16th) and full sky coverage. A first catalog (UCAC1) is being published in early 2000 for 27 million stars. Stars in the range of 9 to 14th magnitude have a positional precision of 20 mas. The UCAC1 will utilize positions from the USNO A2.0 catalog for determining proper motions, which are expected to be about 8 mas/yr for this initial release. Higher precision proper motions, expected to be in the 3 to 4 mas/yr range, will be derived utilizing a variety of early epoch data, including re-measuring of the Southern Proper Motion (SPM) survey first epoch plates.

Parallaxes and Proper Motions From the MCCormick Observatory: List 47

NASA Astrophysics Data System (ADS)

Ianna, Philip A.; Patterson, Richard J.; Swain, Melanie A.

1996-01-01

Trigonometric parallaxes and proper motions are presented for 32 late-type stars observed photographically with the Leander McCormick 67 cm refractor. Eighteen of the stars have no previously published parallaxes. Twenty one of the stars are K and M dwarfs identified by Vyssotsky and his collaborators. The list includes several x-ray luminous M dwarfs, a rapidly rotating spotted flare star, and two astrometric binaries.

VizieR Online Data Catalog: OGLE high proper motion stars towards MC (Soszynski+, 2002)

NASA Astrophysics Data System (ADS)

Soszynski, I.; Zebrun, K.; Udalski, A.; Wozniak, P. R.; Szymanski, M.; Kubiak, M.; Pietrzynski, G.; Szewczyk, O.; Wyrzykowski, L.

2002-11-01

We present a catalog of high proper motion (HPM) stars detected in the foreground of central parts of the Magellanic Clouds. The Catalog contains 2161 objects in the 4.5 square degree area towards the LMC, and 892 HPM stars in the 2.4 square degree area towards the SMC. The Catalog is based on observations collected during four years of the OGLE-II microlensing survey. The Difference Image Analysis (DIA) of the images provided candidate HPM stars with proper motion as small as 4mas/yr. These appeared as pseudo-variables, and were all measured astrometrically on all CCD images, providing typically about 400 data points per star. The reference frame was defined by the majority of background stars, most of them members of the Magellanic Clouds. The reflex motion due to solar velocity with respect to the local standards of rest is clearly seen. The largest proper motion in our sample is 363mas/yr. Parallaxes were measured with errors smaller than 20% for several stars. (2 data files).

Proper Motion of the Compact, Nonthermal Radio Source in the Galactic Center, Sagittarius A*

NASA Astrophysics Data System (ADS)

Backer, D. C.; Sramek, R. A.

1999-10-01

Proper motions and radial velocities of luminous infrared stars in the Galactic center have provided strong evidence for a dark mass of 2.5×106 Msolar in the central 0.05 pc of the Galaxy. The leading hypothesis for this mass is a black hole. High angular resolution measurements at radio wavelengths find a compact radio source, Sagittarius (Sgr) A*, that is either the faint glow from a small amount of material accreting onto the hole with low radiative efficiency or a miniature active galactic nucleus (AGN) core-jet system. This paper provides a full report on the first program that has measured the apparent proper motion of Sgr A* with respect to background extragalactic reference frame. Our current result isμl,*=[-6.18+/-0.19] mas yr-1 μb,*=[-0.65+/-0.17] mas yr-1 . The observations were obtained with the NRAO Very Large Array at 4.9 GHz over 16 yr. The proper motion of Sgr A* provides an estimate of its mass based on equipartition of kinetic energy between the hole and the surrounding stars. The measured motion is largest in galactic longitude. This component of the motion is consistent with the secular parallax that results from the rotation of the solar system about the center, which is a global measure of the difference between Oort's constants (A-B), with no additional peculiar motion of Sgr A*. The current uncertainty in Oort's galactic rotation constants limits the use of this component of the proper motion for a mass inference. In latitude, we find a small, and weakly significant, peculiar motion of Sgr A*, -19+/-7 km s-1 after correction for the motion of the solar system with respect to the local standard of rest. We consider sources of peculiar motion of Sgr A* ranging from unstable radio wave propagation through intervening turbulent plasma to the effects of asymmetric masses in the center. These fail to account for a significant peculiar motion. One can appeal to an m=1 dynamical instability that numerical simulations have revealed. However, the

Proper motion of the Draco dwarf galaxy from Subaru Suprime-Cam data

NASA Astrophysics Data System (ADS)

Casetti-Dinescu, Dana I.; Girard, Terrence M.

2016-09-01

We have measured the absolute proper motion of the Draco dwarf spheroidal galaxy using Subaru Suprime-Cam images taken at three epochs, with time baselines of 4.4 and 7 yr. The magnitude limit of the proper-motion study is I = 25, thus allowing for thousands of background galaxies and Draco stars to be used to perform extensive astrometric tests and to derive the correction to an inertial reference frame. The derived proper motion is (μα, μδ) = (-0.284 ± 0.047, -0.289 ± 0.041) mas yr-1. This motion implies an orbit that takes Draco to a pericentre of ˜20 kpc; a somewhat disruptive orbit suggesting that tides might account for the rising velocity-dispersion profile of Draco seen in line-of-sight velocity studies. The orbit is only marginally consistent with Draco's membership to the vast polar structure of Galactic satellites, in contrast to a recent Hubble Space Telescope proper-motion measurement that finds alignment very likely. Our study is a test case to demonstrate that deep imaging with mosaic cameras of appropriate resolution can be used for high-accuracy, ground-based proper-motion measurement. As a useful by-product of the study, we also identify two faint brown-dwarf candidates in the foreground field.

A new UKIDSS proper motion survey and key early results, including new benchmark systems

NASA Astrophysics Data System (ADS)

Smith, L.; Lucas, P.; Burningham, B.; Jones, H.; Pinfield, D.; Smart, R.; Andrei, A.

We present a proper motion catalogue for the 1500 deg2 of 2 epoch J-band UKIDSS Large Area Survey (LAS) data, which includes 120,000 stellar sources with motions detected above the 5sigma level. Our upper limit on proper motion detection is 3\\farcs3 yr-1 and typical uncertainties are of order 10 mas yr-1 for bright sources from data with a modest 1.8-7.0 year epoch baseline. We developed a bespoke proper motion pipeline which applies a source-unique second order polynomial transformation to UKIDSS array coordinates to counter potential local non-uniformity in the focal plane. Our catalogue agrees well with the proper motion data supplied in the current WFCAM Science Archive (WSA) tenth data release (DR10) catalogue where there is overlap, and in various optical catalogues, but it benefits from some improvements, such as a larger matching radius and relative to absolute proper motion correction. We present proper motion results for 128 T dwarfs in the UKIDSS LAS and key early results of projects utilising our catalogue, in particular searches for brown dwarf benchmark systems through cross matches with existing proper motion catalogues. We report the discovery of two new T dwarf benchmark systems.

A Spectroscopic Catalog of Nearby, High Proper Motion M subdwarfs

NASA Astrophysics Data System (ADS)

Hejazi, Neda; Lepine, Sebastien; Homeier, Derek

2018-01-01

We present a catalog of 350 metal-poor M subdwarfs, most of them likely from the local Galactic halo population, assembled from medium-resolution observations made at the MDM observatory. All objects are high proper motion stars, with 257 of them having proper motions > 0.4"/yr. We have identified the brightest prototypes for each bin of a grid of 14 spectral subtypes (M0, M0.5, M1, … M6.5) and 9 metallicity bins that go from the moderately metal-poor subdwarfs (sdM), to the more metal-poor extreme subdwarfs (esdM), to the most metal-poor ultra subdwarfs (usdM), each of which is subdivided into three finer metallicity subclasses. The spectral classification by subtype and metallicity class has been determined by a template-fit method, and confirmed by synthetic-model fitting using the BT-Settl spectral grid. We provide the list of the brightest prototypes for each subtype/subclass, as a guide for future high-resolution surveys of low-mass, metal-poor stars.

Constraining the radio jet proper motion of the high-redshift quasar J2134-0419 at z = 4.3

NASA Astrophysics Data System (ADS)

Perger, Krisztina; Frey, Sándor; Gabányi, Krisztina É.; An, Tao; Britzen, Silke; Cao, Hong-Min; Cseh, Dávid; Dennett-Thorpe, Jane; Gurvits, Leonid I.; Hong, Xiao-Yu; Hook, Isobel M.; Paragi, Zsolt; Schilizzi, Richard T.; Yang, Jun; Zhang, Yingkang

2018-06-01

To date, PMN J2134-0419 (at a redshift z = 4.33) is the second most distant quasar known with a milliarcsecond-scale morphology permitting direct estimates of the jet proper motion. Based on two-epoch observations, we constrained its radio jet proper motion using the very long baseline interferometry (VLBI) technique. The observations were conducted with the European VLBI Network (EVN) at 5 GHz on 1999 November 26 and 2015 October 6. We imaged the central 10-pc scale radio jet emission and modelled its brightness distribution. By identifying a jet component at both epochs separated by 15.86 yr, a proper motion of μ = 0.035 ± 0.023 mas yr-1 is found. It corresponds to an apparent superluminal speed of βa = 4.1 ± 2.7 c. Relativistic beaming at both epochs suggests that the jet viewing angle with respect to the line of sight is smaller than 20°, with a minimum bulk Lorentz factor Γ = 4.3. The small value of the proper motion is in good agreement with the expectations from the cosmological interpretation of the redshift and the current cosmological model. Additionally we analysed archival Very Large Array observations of J2143-0419 and found indication of a bent jet extending to ˜30 kpc.

Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. II. Measurement for Carina

NASA Astrophysics Data System (ADS)

Piatek, Slawomir; Pryor, Carlton; Olszewski, Edward W.; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

2003-11-01

This article presents and discusses a measurement of the proper motion for the Carina dwarf spheroidal galaxy (dSph) from images in two distinct fields in the direction of Carina taken with the Hubble Space Telescope, at three epochs. Each field contains a confirmed quasi-stellar object that is the reference point for measuring the proper motion of the dSph. The consecutive epochs are 1-2 yr apart. The components of the measured proper motion for Carina, expressed in the equatorial coordinate system, are μα=22+/-9 mas century-1 and μδ=15+/-9 mas century-1. The quoted proper motion is a weighted mean of two independent measurements and has not been corrected for the motions of the Sun and of the local standard of rest. Given the proper motion and its uncertainty, integrating the family of possible orbits of Carina in a realistic gravitational potential for the Milky Way indicates that Carina is bound gravitationally to the Milky Way and is close to apogalacticon. The best estimate of, and the 95% confidence interval for, the apogalacticon of the orbit is 102 kpc and (102,113) kpc, for the perigalacticon is 20 kpc and (3.0,63) kpc, and for the orbital period is 1.4 Gyr and (1.3,2.0) Gyr. Carina does not seem to be on a polar orbit. The best estimate of the inclination of the orbit with respect to the Galactic plane is 39°, but the 95% confidence interval is so wide, (23°,102°), that it includes a polar orbit. We are unable to confirm or to rule out the membership of Carina in a ``stream'' of galaxies in the Galactic halo because the difference between the observed and predicted directions of the proper motion is 1.6 times the uncertainty of the difference. Carina must contain dark matter to have survived the tidal interaction with the Milky Way until the present. The triggering of star formation by perigalacticon passages and crossings of the Galactic disk do not explain the history of star formation in Carina. Based on observations with NASA/ESA Hubble Space

The VMC survey. XXX. Stellar proper motions in the central parts of the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Niederhofer, F.; Cioni, M.-R. L.; Rubele, S.; Schmidt, T.; Bekki, K.; Grijs, R. de; Emerson, J.; Ivanov, V. D.; Marconi, M.; Oliveira, J. M.; Petr-Gotzens, M. G.; Ripepi, V.; van Loon, J. Th.; Zaggia, S.

2018-05-01

We present the first spatially resolved map of stellar proper motions within the central ( 3.1 × 2.4 kpc) regions of the Small Magellanic Cloud (SMC). The data used for this study encompasses four tiles from the ongoing near-infrared VISTA survey of the Magellanic Clouds system and covers a total contiguous area on the sky of 6.81 deg2. Proper motions have been calculated independently in two dimensions from the spatial offsets in the Ks filter over time baselines between 22 and 27 months. The reflex motions of approximately 33 000 background galaxies are used to calibrate the stellar motions to an absolute scale. The resulting catalog is composed of more than 690 000 stars which have been selected based on their position in the (J - Ks, Ks) color-magnitude diagram. For the median absolute proper motion of the SMC, we find (μαcos(δ), μδ) = (1.087 ± 0.192 (sys.) ± 0.003 (stat.), -1.187 ± 0.008 (sys.) ± 0.003 (stat.)) mas yr-1, consistent with previous studies. Mapping the proper motions as a function of position within the SMC reveals a nonuniform velocity pattern indicative of a tidal feature behind the main body of the SMC and a flow of stars in the south-east moving predominantly along the line-of-sight. Based on observations made with VISTA at the Paranal Observatory under program ID 179.B-2003.

Cresting the wave: proper motions of the Eastern Banded Structure

NASA Astrophysics Data System (ADS)

Deason, Alis J.; Belokurov, Vasily; Koposov, Sergey E.

2018-01-01

We study the kinematic properties of the Eastern Banded Structure (EBS) and Hydra I overdensity using exquisite proper motions derived from the Sloan Digital Sky Survey (SDSS) and Gaia source catalogue. Main sequence turn-off stars in the vicinity of the EBS are identified from SDSS photometry; we use the proper motions and, where applicable, spectroscopic measurements of these stars to probe the kinematics of this apparent stream. We find that the EBS and Hydra I share common kinematic and chemical properties with the nearby Monoceros Ring. In particular, the proper motions of the EBS, like Monoceros, are indicative of prograde rotation (Vϕ ∼ 180-220 km s-1), which is similar to the Galactic thick disc. The kinematic structure of stars in the vicinity of the EBS suggests that it is not a distinct stellar stream, but rather marks the 'edge' of the Monoceros Ring. The EBS and Hydra I are the latest substructures to be linked with Monoceros, leaving the Galactic anti-centre a mess of interlinked overdensities which likely share a unified, Galactic disc origin.

The First X-Ray Proper-Motion Measurements of the Forward Shock in the Northeastern Limb of Sn 1006

NASA Technical Reports Server (NTRS)

Katsuda, Satoru; Petre, Robert; Long, Knox S.; Reynolds, Stephen P.; Winkler, P. Frank; Mori, Koji; Tsunemi, Hiroshi

2009-01-01

We report on the first X-ray proper-motion measurements of the nonthermally-dominated forward shock in the northeastern limb of SN 1006, based on two Chandra observations taken in 2000 and 2008. We find that the proper motion of the forward shock is about 0.48"/yr and does not vary around the rim within the approx.10% measurement uncertainties. The proper motion measured is consistent with that determined by the previous radio observations. The mean expansion index of the forward shock is calculated to be approx..0.54 which matches the value expected based on an evolutionary model of a Type Ia supernova with either a power-law or an exponential ejecta density profile. Assuming pressure equilibrium around the periphery from the thermally-dominated northwestern rim to the nonthermally-dominated northeastern rim, we estimate the ambient density to the northeast of SN 1006 to be approx..0.085/cu cm.

A deep proper motion catalog within the Sloan digital sky survey footprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munn, Jeffrey A.; Harris, Hugh C.; Tilleman, Trudy M.

2014-12-01

A new proper motion catalog is presented, combining the Sloan Digital Sky Survey (SDSS) with second epoch observations in the r band within a portion of the SDSS imaging footprint. The new observations were obtained with the 90prime camera on the Steward Observatory Bok 90 inch telescope, and the Array Camera on the U.S. Naval Observatory, Flagstaff Station, 1.3 m telescope. The catalog covers 1098 square degrees to r = 22.0, an additional 1521 square degrees to r = 20.9, plus a further 488 square degrees of lesser quality data. Statistical errors in the proper motions range from 5 masmore » year{sup −1} at the bright end to 15 mas year{sup −1} at the faint end, for a typical epoch difference of six years. Systematic errors are estimated to be roughly 1 mas year{sup −1} for the Array Camera data, and as much as 2–4 mas year{sup −1} for the 90prime data (though typically less). The catalog also includes a second epoch of r band photometry.« less

Positions and proper motions of dwarf carbon stars

NASA Technical Reports Server (NTRS)

Deutsch, Eric W.

1994-01-01

Recent-epochs positions and proper motions of nine dwarf carbon star candidates are presented along with finding charts for each object. Measurements are obtained from digitized Palomar Observatory Sky Survey (POSS) and Quik V plate archives at the Space Telescope Science Institute, and from recent CCD images.

Update of membership and mean proper motion of open clusters from UCAC5 catalog

NASA Astrophysics Data System (ADS)

Dias, W. S.; Monteiro, H.; Assafin, M.

2018-06-01

We present mean proper motions and membership probabilities of individual stars for optically visible open clusters, which have been determined using data from the UCAC5 catalog. This follows our previous studies with the UCAC2 and UCAC4 catalogs, but now using improved proper motions in the GAIA reference frame. In the present study results were obtained for a sample of 1108 open clusters. For five clusters, this is the first determination of mean proper motion, and for the whole sample, we present results with a much larger number of identified astrometric member stars than on previous studies. It is the last update of our Open cluster Catalog based on proper motion data only. Future updates will count on astrometric, photometric and spectroscopic GAIA data as input for analyses.

Proper motions and membership probabilities of stars in the region of globular cluster NGC 6366

NASA Astrophysics Data System (ADS)

Sariya, Devesh P.; Yadav, R. K. S.

2015-12-01

Context. NGC 6366 is a metal-rich globular cluster that is relatively unstudied. It is a kinematically interesting cluster, reported as belonging to the slowly rotating halo system, which is unusual given its metallicity and spatial location in the Galaxy. Aims: The purpose of this research is to determine the relative proper motion and membership probability of the stars in the region of globular cluster NGC 6366. To target cluster members reliably during spectroscopic surveys without including field stars, a good proper motion and membership probability catalogue of NGC 6366 is needed. Methods: To derive relative proper motions, the archival data from the Wide Field Imager mounted on the ESO 2.2 m telescope have been reduced using a high precision astrometric software. The images used are in the B,V, and I photometric bands with an epoch gap of ~3.2 yr. The calibrated BVI magnitudes have been determined using recent data for secondary standard stars. Results: We determined relative proper motions and cluster membership probabilities for 2530 stars in the field of globular cluster NGC 6366. The median proper motion rms errors for stars brighter than V ~ 18 mag is ~2 mas yr-1, which gradually increases to ~5 mas yr-1 for stars having magnitudes V ~ 20 mag. Based on the membership catalogue, we checked the membership status of the X-ray sources and variable stars of NGC 6366 mentioned in the literature. We also provide the astronomical community with an electronic catalogue that includes B, V, and I magnitudes; relative proper motions; and membership probabilities of the stars in the region of NGC 6366. Based on observations with the MPG/ESO 2.2 m and ESO/VLT telescopes, located at La Silla and Paranal Observatory, Chile, under DDT programs 164.O-0561(F), 71.D-0220(A) and the archive material.Full Table 4 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/584/A59

The Optical Gravitational Lensing Experiment: catalogue of stellar proper motions in the OGLE-II Galactic bulge fields

NASA Astrophysics Data System (ADS)

Sumi, T.; Wu, X.; Udalski, A.; Szymański, M.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Woźniak, P.; Żebruń, K.; Szewczyk, O.; Wyrzykowski, Ł.

2004-03-01

We present a proper-motion (μ) catalogue of 5 080 236 stars in 49 Optical Gravitational Lensing Experiment II (OGLE-II) Galactic bulge (GB) fields, covering a range of -11° < l < 11° and -6° < b < 3°, the total area close to 11 deg2. The proper-motion measurements are based on 138-555 I-band images taken during four observing seasons: 1997-2000. The catalogue stars are in the magnitude range 11 < I < 18 mag. In particular, the catalogue includes red clump giants and red giants in the GB, and main-sequence stars in the Galactic disc. The proper motions up to μ= 500 mas yr-1 were measured with a mean accuracy of 0.8-3.5 mas yr-1, depending on the brightness of a star. This catalogue may be useful for studying the kinematics of stars in the GB and the Galactic disc.

Chemically-dissected Rotation Curves of the Galactic Bulge from Hubble Space Telescope Proper Motions on the Main Sequence

NASA Astrophysics Data System (ADS)

Clarkson, William I.; Calamida, Annalisa; Sahu, Kailash C.; Gennaro, Mario; Brown, Thomas M.; Avila, Roberto J.; Rich, R. Michael; Debattista, Victor P.

2018-01-01

We report results from a pilot study using archival Hubble Space Telescope imaging observations in seven filters over a multi-year time-baseline to probe the co-dependence of chemical abundance and kinematics, using proper motion-based rotation curves selected on relative metallicity. With spectroscopic studies suggesting the metallicity distribution of the Bulge may be bimodal, we follow a data-driven approach to classify stars as belonging to metal-rich or metal-poor ends of the observed relative photometric metallicity distribution, with classification implemented using standard unsupervised learning techniques. We detect clear differences in both slope and amplitude of the proper motion-based rotation curve as traced by the more “metal-rich” and “metal-poor” samples. The sense of the discrepancy is qualitatively in agreement both with recent observational and theoretical indications; the “metal-poor” sample does indeed show a weaker rotation signature.This is the first study to dissect the proper motion rotation curve of the Bulge by chemical abundance using main-sequence targets, which are orders of magnitude more common on the sky than bright giants. These techniques thus offer a pencil-beam complement to wide-field studies that use more traditional tracer populations.

X-ray Proper Motions and Shock Speeds along the Northwest Rim of SN1006

NASA Technical Reports Server (NTRS)

Katsuda, Satoru; Long, Knox S.; Petre, Robert; Reynolds, Stephen P.; Williams, Brian J.; Winkler, P. Frank

2012-01-01

We report the results of an X-ray proper motion measurement for the NW rim of SN 1006, carried out by comparing Chandra observations from 2001 and 2012. The NW limb has predominantly thermal X-ray emission, and it is the only location in SN 1006 with signi cant optical emission: a thin, Balmer-dominated lament. For most of the NW rim, the proper motion is approximately equal to 0.30"yr(exp -1), essentially the same as has been measured from the H alpha lament. Isolated regions of the NW limb are dominated by nonthermal emission, and here the proper motion is much higher, 0:49"yr(exp -1), close to the value measured in X-rays along the much brighter NE limb, where the X-rays are overwhelmingly nonthermal. At the 2.2 kpc distance to SN 1006, the proper motions imply shock velocities of approximately 3000 kms(exp -1) and approximately 5000 kms(exp -1) in the thermal and nonthermal regions, respectively. A lower velocity behind the H alpha filament is consistent with the picture that SN 1006 is encountering denser gas in the NW, as is also suggested by its overall morphology. In the thermally-dominated portion of the X-ray shell, we also see an o set in the radial profiles at different energies; the 0.5-0.6 keV peak dominated by O VII is closer to the shock front than that of the 0.8-3 keV emission|due to the longer times for heavier elements to reach ionization states where they produce strong X-ray emission.

Proper motion of the radio pulsar B1727-47 and its association with the supernova remnant RCW 114

NASA Astrophysics Data System (ADS)

Shternin, P. S.; Yu, M.; Kirichenko, A. Yu; Shibanov, Yu A.; Danilenko, A. A.; Voronkov, M. A.; Zyuzin, D. A.

2017-12-01

We report preliminary results of the analysis of the proper motion of the bright radio pulsar B1727-47. Using archival Parkes timing data, as well as original and archival ATCA interferometry observations, we, for the first time, constrain the pulsar proper motion at the level of 148±11 mas yr-1. The backward extrapolation of the proper motion vector to the pulsar birth epoch points at the center of the Galactic supernova remnant RCW 114 suggesting the genuine association between the two objects. We discuss the implications of the association and argue that the distance to the system is less than 1 kpc. This value is at least two times lower than the dispersion measure distance estimates. This suggests that the existing Galaxy electron density models are incomplete in the direction to the pulsar.

The Optical Gravitational Lensing Experiment Catalog of stellar proper motions in the OGLE-II Galactic bulge fields

NASA Astrophysics Data System (ADS)

Sumi, T.; Wu, X.; Udalski, A.; Szymański, M.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Woźniak, P.; Zebruń, K.; Szewczyk, O.; Wyrzykowski, L.

2003-12-01

We present proper motion (μ ) catalogue of 5,078,188 stars in 49 Optical Gravitational Lensing Experiment II (OGLE-II) Galactic bulge fields, with the total area close to 11 square degrees. The proper motion measurements are based on 138 - 555 I-band images taken during four observing seasons: 1997-2000. The catalogue stars are in the magnitude range 11 < I < 18 mag. In particular, the catalogue includes Red Clump Giants (RCGs) and Red Giants in the Galactic Bulge, and main sequence stars in the Galactic disc. The proper motions up to μ = 500 mas yr -1 were measured with the mean accuracy of 0.8 ˜ 3.5 mas yr-1, depending on the brightness of a star. This catalogue may be useful for studying the kinematic of stars in the Galactic Bulge and the Galactic disk with Extinction maps in these fields which are construncted by using two-band photometry of RCGs.

Analyzing the Proper Motion of Two Double Star Systems from Astrometric Measurements

NASA Astrophysics Data System (ADS)

Falatoun, Alex; Barrera, Janet; de Neef, Anna; Gonzalez, Aura; Calanog, Jae; Boyce, Pat; Boyce, Grady

2018-04-01

The iTelescope network was used to obtain astrometric measurements of double star systems WDS 12202-1408 (STF 1631) and WDS 12339+5522 (STI 2286). Through astrometric measurement softwares SAOImage DS9 and Mira Pro x64, a mean position angle for STF 1631 of 304.8° ± 0.9° and a mean separation 14.7" ± 0.2" was measured. For STI 2286, a newly measured mean position angle of 85.9° ± 0.9° and mean separation 11.5" ± 0.3" were obtained. The relative proper motion of 1631 shows that the system could be demonstrating a linear path or an approximately circular orbit with a period of 1400 years. Parallax measurements of the secondary star will aid in classifying if this system is a physical or a visual pair. The proper motion of STI 2286 indicates that it could be a physical pair, featuring an orbit nearing a turning point. Follow-up observations in three to four year intervals will further validate or refute this claim and constrain the shape of a possible orbit.

Predicted space motions for hypervelocity and runaway stars: proper motions and radial velocities for the Gaia Era

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenyon, Scott J.; Brown, Warren R.; Geller, Margaret J.

We predict the distinctive three-dimensional space motions of hypervelocity stars (HVSs) and runaway stars moving in a realistic Galactic potential. For nearby stars with distances less than 10 kpc, unbound stars are rare; proper motions alone rarely isolate bound HVSs and runaways from indigenous halo stars. At large distances of 20-100 kpc, unbound HVSs are much more common than runaways; radial velocities easily distinguish both from indigenous halo stars. Comparisons of the predictions with existing observations are encouraging. Although the models fail to match observations of solar-type HVS candidates from SEGUE, they agree well with data for B-type HVS andmore » runaways from other surveys. Complete samples of g ≲ 20 stars with Gaia should provide clear tests of formation models for HVSs and runaways and will enable accurate probes of the shape of the Galactic potential.« less

Dynamical analysis of nearby clusters. Automated astrometry from the ground: precision proper motions over a wide field

NASA Astrophysics Data System (ADS)

Bouy, H.; Bertin, E.; Moraux, E.; Cuillandre, J.-C.; Bouvier, J.; Barrado, D.; Solano, E.; Bayo, A.

2013-06-01

Context. The kinematic properties of the different classes of objects in a given association hold important clues about the history of its members, and offer a unique opportunity to test the predictions of the various models of stellar formation and evolution. Aims: DANCe (standing for dynamical analysis of nearby clusters) is a survey program aimed at deriving a comprehensive and homogeneous census of the stellar and substellar content of a number of nearby (<1 kpc) young (<500 Myr) associations. Whenever possible, members will be identified based on their kinematics properties, ensuring little contamination from background and foreground sources. Otherwise, the dynamics of previously confirmed members will be studied using the proper motion measurements. We present here the method used to derive precise proper motion measurements, using the Pleiades cluster as a test bench. Methods: Combining deep wide-field multi-epoch panchromatic images obtained at various obervatories over up to 14 years, we derived accurate proper motions for the sources in the field of the survey. The datasets cover ≈80 square degrees, centered around the Seven Sisters. Results: Using new tools, we have computed a catalog of 6 116 907 unique sources, including proper motion measurements for 3 577 478 of them. The catalog covers the magnitude range between i = 12 ~ 24 mag, achieving a proper motion accuracy <1 mas y-1 for sources as faint as i = 22.5 mag. We estimate that our final accuracy reaches 0.3 mas yr-1 in the best cases, depending on magnitude, observing history, and the presence of reference extragalactic sources for the anchoring onto the ICRS. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the

SIMP: A Near-Infrared Proper Motion Survey

NASA Astrophysics Data System (ADS)

Artigau, Étienne; Lafrenière, David; Doyon, René; Albert, Loïc; Robert, Jasmin; Malo, Lison

2009-02-01

SIMP is a proper motion (PM) survey made with the Observatoire du Mont Mégantic (OMM) wide-field near-infrared camera CPAPIR at the CTIO 1.5 m and OMM 1.6 m telescopes. The SIMP observations were initiated in early 2005, are still ongoing and, to date, have covered 28% of the sky at high galactic latitudes. The PMs of the sources detected are determined by comparing their measured positions with those listed in the 2MASS point source catalog, giving a time baseline of 4 to 10 years. The 5 σ uncertainty on the relative SIMP and 2MASS astrometry is 1'', equivalent to a PM lower limit of 0.125-0.250''/yr, or a tangential velocity limit of 15-30 km/s at 25 pc. Up to the 2MASS magnitude limit (J~16.5), T dwarfs are found out to ~25 pc, while L dwarfs may be found as far as 100 pc away.

Messier 35 (NGC 2168) DANCe. I. Membership, proper motions, and multiwavelength photometry

NASA Astrophysics Data System (ADS)

Bouy, H.; Bertin, E.; Barrado, D.; Sarro, L. M.; Olivares, J.; Moraux, E.; Bouvier, J.; Cuillandre, J.-C.; Ribas, Á.; Beletsky, Y.

2015-03-01

Context. Messier 35 (NGC 2168) is an important young nearby cluster. Its age, richness and relative proximity make it an ideal target for stellar evolution studies. The Kepler K2 mission recently observed it and provided a high accuracy photometric time series of a large number of sources in this area of the sky. Identifying the cluster's members is therefore of high importance to optimize the interpretation and analysis of the Kepler K2 data. Aims: We aim to identify the cluster's members by deriving membership probabilities for the sources within 1° of the cluster's center, which is farther away than equivalent previous studies. Methods: We measure accurate proper motions and multiwavelength (optical and near-infrared) photometry using ground-based archival images of the cluster. We use these measurements to compute membership probabilities. The list of candidate members from the literature is used as a training set to identify the cluster's locus in a multidimensional space made of proper motions, luminosities, and colors. Results: The final catalog includes 338 892 sources with multiwavelength photometry. Approximately half (194 452) were detected at more than two epochs and we measured their proper motion and used it to derive membership probability. A total of 4349 candidate members with membership probabilities greater than 50% are found in this sample in the luminosity range between 10 mag and 22 mag. The slow proper motion of the cluster and the overlap of its sequence with the field and background sequences in almost all color-magnitude and color-color diagrams complicate the analysis and the contamination level is expected to be significant. Our study, nevertheless, provides a coherent and quantitative membership analysis of Messier 35 based on a large fraction of the best ground-based data sets obtained over the past 18 years. As such, it represents a valuable input for follow-up studies using, in particular, the Kepler K2 photometric time series

The VMC survey. XXVIII. Improved measurements of the proper motion of the Galactic globular cluster 47 Tucanae

NASA Astrophysics Data System (ADS)

Niederhofer, Florian; Cioni, Maria-Rosa L.; Rubele, Stefano; Schmidt, Thomas; Bekki, Kenji; de Grijs, Richard; Emerson, Jim; Ivanov, Valentin D.; Oliveira, Joana M.; Petr-Gotzens, Monika G.; Ripepi, Vincenzo; Sun, Ning-Chen; van Loon, Jacco Th.

2018-05-01

We use deep multi-epoch point-spread function (PSF) photometry taken with the Visible and Infrared Survey Telescope for Astronomy (VISTA) to measure and analyze the proper motions of stars within the Galactic globular cluster 47 Tucanae (47 Tuc, NGC 104). The observations are part of the ongoing near-infrared VISTA survey of the Magellanic Cloud system (VMC). The data analyzed in this study correspond to one VMC tile, which covers a total sky area of 1.77 deg2. Absolute proper motions with respect to 9070 background galaxies are calculated from a linear regression model applied to the positions of stars in 11 epochs in the Ks filter. The data extend over a total time baseline of about 17 months. We found an overall median proper motion of the stars within 47 Tuc of (μαcos(δ), μδ) = (+5.89 ± 0.02 (statistical) ± 0.13 (systematic), -2.14 ± 0.02 (statistical) ± 0.08 (systematic)) mas yr-1, based on the measurements of 35 000 individual sources between 5' and 42' from the cluster center. We compared our result to the proper motions from the newest US Naval Observatory CCD Astrograph Catalog (UCAC5), which includes data from the Gaia data release 1. Selecting cluster members ( 2700 stars), we found a median proper motion of (μαcos(δ), μδ) = (+5.30 ± 0.03 (statistical) ± 0.70 (systematic), -2.70 ± 0.03 (statistical) ± 0.70 (systematic)) mas yr-1. Comparing the results with measurements in the literature, we found that the values derived from the VMC data are consistent with the UCAC5 result, and are close to measurements obtained using the Hubble Space Telescope. We combined our proper motion results with radial velocity measurements from the literature and reconstructed the orbit of 47 Tuc, finding that the cluster is on an orbit with a low ellipticity and is confined within the inner 7.5 kpc of the Galaxy. We show that the use of an increased time baseline in combination with PSF-determined stellar centroids in crowded regions significantly improves

Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. IV. Measurement for Sculptor

NASA Astrophysics Data System (ADS)

Piatek, Slawomir; Pryor, Carlton; Bristow, Paul; Olszewski, Edward W.; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

2006-03-01

This article presents a measurement of the proper motion of the Sculptor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope using the Space Telescope Imaging Spectrograph in the imaging mode. Each of two distinct fields contains a quasi-stellar object that serves as the ``reference point.'' The measured proper motion of Sculptor, expressed in the equatorial coordinate system, is (μα, μδ)=(9+/-13, 2+/-13) mas century-1. Removing the contributions from the motion of the Sun and the motion of the local standard of rest produces the proper motion in the Galactic rest frame: (μGrfα, μGrfδ)=(-23+/-13, 45+/-13) mas century-1. The implied space velocity with respect to the Galactic center has a radial component of Vr=79+/-6 km s-1 and a tangential component of Vt=198+/-50 km s-1. Integrating the motion of Sculptor in a realistic potential for the Milky Way produces orbital elements. The perigalacticon and apogalacticon are 68 (31, 83) and 122 (97, 313) kpc, respectively, where the values in the parentheses represent the 95% confidence interval derived from Monte Carlo experiments. The eccentricity of the orbit is 0.29 (0.26, 0.60), and the orbital period is 2.2 (1.5, 4.9) Gyr. Sculptor is on a polar orbit around the Milky Way: the angle of inclination is 86° (83°, 90°). Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

THE EFFECT OF UNRESOLVED BINARIES ON GLOBULAR CLUSTER PROPER-MOTION DISPERSION PROFILES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bianchini, P.; Norris, M. A.; Ven, G. van de

2016-03-20

High-precision kinematic studies of globular clusters (GCs) require an accurate knowledge of all possible sources of contamination. Among other sources, binary stars can introduce systematic biases in the kinematics. Using a set of Monte Carlo cluster simulations with different concentrations and binary fractions, we investigate the effect of unresolved binaries on proper-motion dispersion profiles, treating the simulations like Hubble Space Telescope proper-motion samples. Since GCs evolve toward a state of partial energy equipartition, more-massive stars lose energy and decrease their velocity dispersion. As a consequence, on average, binaries have a lower velocity dispersion, since they are more-massive kinematic tracers. Wemore » show that, in the case of clusters with high binary fractions (initial binary fractions of 50%) and high concentrations (i.e., closer to energy equipartition), unresolved binaries introduce a color-dependent bias in the velocity dispersion of main-sequence stars of the order of 0.1–0.3 km s{sup −1} (corresponding to 1%−6% of the velocity dispersion), with the reddest stars having a lower velocity dispersion, due to the higher fraction of contaminating binaries. This bias depends on the ability to distinguish binaries from single stars, on the details of the color–magnitude diagram and the photometric errors. We apply our analysis to the HSTPROMO data set of NGC 7078 (M15) and show that no effect ascribable to binaries is observed, consistent with the low binary fraction of the cluster. Our work indicates that binaries do not significantly bias proper-motion velocity-dispersion profiles, but should be taken into account in the error budget of kinematic analyses.« less

Proper motion of the Draco dwarf galaxy based on Hubble space telescope imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pryor, Carlton; Piatek, Slawomir; Olszewski, Edward W., E-mail: pryor@physics.rutgers.edu, E-mail: piatek@physics.rutgers.edu, E-mail: eolszewski@as.arizona.edu

2015-02-01

We have measured the proper motion of the Draco dwarf galaxy using images at two epochs with a time baseline of about two years taken with the Hubble Space Telescope Advanced Camera for Surveys. Wide Field Channels 1 and 2 provide two adjacent fields, each containing a known QSO. The zero point for the proper motion is determined using both background galaxies and the QSOs and the two methods produce consistent measurements within each field. Averaging the results from the two fields gives a proper motion in the equatorial coordinate system of (μ{sub α},μ{sub δ})=(17.7±6.3,−22.1±6.3) mas century{sup −1} and inmore » the Galactic coordinate system of (μ{sub ℓ},μ{sub b})=(−23.1±6.3,−16.3±6.3) mas century{sup −1}. Removing the contributions of the motion of the Sun and of the LSR to the measured proper motion yields a Galactic rest-frame proper motion of (μ{sub α}{sup Grf},μ{sub δ}{sup Grf})=(51.4±6.3,−18.7±6.3) mas century{sup −1} and (μ{sub ℓ}{sup Grf},μ{sub b}{sup Grf})=(−21.8±6.3,−50.1±6.3) mas century{sup −1}. The implied space velocity with respect to the Galactic center is (Π,Θ,Z)=(27±14,89±25,−212±20) km s{sup −1}. This velocity implies that the orbital inclination is 70{sup ∘}, with a 95% confidence interval of (59{sup ∘},80{sup ∘}), and that the plane of the orbit is consistent with that of the vast polar structure (VPOS) of Galactic satellite galaxies.« less

MOTION VERIFIED RED STARS (MoVeRS): A CATALOG OF PROPER MOTION SELECTED LOW-MASS STARS FROM WISE, SDSS, AND 2MASS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Theissen, Christopher A.; West, Andrew A.; Dhital, Saurav, E-mail: ctheisse@bu.edu

2016-02-15

We present a photometric catalog of 8,735,004 proper motion selected low-mass stars (KML-spectral types) within the Sloan Digital Sky Survey (SDSS) footprint, from the combined SDSS Data Release 10 (DR10), Two Micron All-Sky Survey (2MASS) point-source catalog (PSC), and Wide-field Infrared Survey Explorer (WISE) AllWISE catalog. Stars were selected using r − i, i − z, r − z, z − J, and z − W1 colors, and SDSS, WISE, and 2MASS astrometry was combined to compute proper motions. The resulting 3,518,150 stars were augmented with proper motions for 5,216,854 earlier type stars from the combined SDSS and United States Naval Observatory B1.0 catalog (USNO-B). We used SDSS+USNO-B proper motionsmore » to determine the best criteria for selecting a clean sample of stars. Only stars whose proper motions were greater than their 2σ uncertainty were included. Our Motion Verified Red Stars catalog is available through SDSS CasJobs and VizieR.« less

Proper motions of five OB stars with candidate dusty bow shocks in the Carina Nebula

NASA Astrophysics Data System (ADS)

Kiminki, Megan M.; Smith, Nathan; Reiter, Megan; Bally, John

2017-06-01

We constrain the proper motions of five OB stars associated with candidate stellar wind bow shocks in the Carina Nebula using Hubble Space Telescope ACS imaging over 9-10 yr baselines. These proper motions allow us to directly compare each star's motion to the orientation of its candidate bow shock. Although these stars are saturated in our imaging, we assess their motion by the shifts required to minimize residuals in their airy rings. The results limit the direction of each star's motion to sectors less than 90° wide. None of the five stars are moving away from the Carina Nebula's central clusters as runaway stars would be, confirming that a candidate bow shock is not necessarily indicative of a runaway star. Two of the five stars are moving tangentially relative to the orientation of their candidate bow shocks, both of which point at the OB cluster Trumpler 14. In these cases, the large-scale flow of the interstellar medium, powered by feedback from the cluster, appears to dominate over the motion of the star in producing the observed candidate bow shock. The remaining three stars all have some component of motion towards the central clusters, meaning that we cannot distinguish whether their candidate bow shocks are indicators of stellar motion, of the flow of ambient gas or of density gradients in their surroundings. In addition, these stars' lack of outward motion hints that the distributed massive-star population in Carina's South Pillars region formed in place, rather than migrating out from the association's central clusters.

Testing stellar proper motions of TGAS stars using data from the HSOY, UCAC5 and PMA catalogues

NASA Astrophysics Data System (ADS)

Fedorov, P. N.; Akhmetov, V. S.; Velichko, A. B.

2018-05-01

We analyse the stellar proper motions from the Tycho-Gaia Astrometric Solution (TGAS) and those from the ground-based HSOY, UCAC5 and PMA catalogues derived by combining them with Gaia DR1 space data. Assuming that systematic differences in stellar proper motions of the two catalogues are caused by a mutual rigid-body rotation of the reference catalogue systems, we analyse components of the rotation vector between the systems. We found that the ωy component of the rotation vector is ˜1.5 mas yr-1 and it depends non-linearly on stellar magnitude for the objects of 9.5-11.5 mag used in all three comparisons of the catalogues HSOY, UCAC5 and PMA with respect to TGAS. We found that the Tycho-2 stars in TGAS appeared to have an inexplicable dependence of proper motion on stellar magnitude. We showed that the proper motions of the TGAS stars derived using AGIS differ from those obtained by the conventional (classical) method. Moreover, the application of both methods has not revealed such a difference between the proper motions of the Hipparcos and TGAS stars. An analysis of the systematic differences between the proper motions of the TGAS stars derived by the classical method and the proper motions of the HSOY, UCAC5 and PMA stars shows that the ωy component here does not depend on the magnitude. This indicates unambiguously that there is a magnitude error in the proper motions of the Tycho-2 stars derived with the AGIS.

A Proper-Motion Corrected, Cross-Matched Catalog Of M Dwarfs In SDSS And FIRST

NASA Astrophysics Data System (ADS)

Arai, Erin; West, A. A.; Thyagarajan, N.; Agüeros, M.; Helfand, D.

2011-05-01

We present a preliminary analysis of M dwarfs identified in both the Sloan Digital Sky Survey (SDSS) and the Very Large Array's (VLA) Faint Images of the Radio Sky at Twenty-centimeters survey (FIRST). The presence of magnetic fields is often associated with indirect magnetic activity measurements, such as H-alpha or X-ray emission. Radio emission, in contrast, is directly proportional to the magnetic field strength in addition to being another measure of activity. We search for stellar radio emission by cross-matching the SDSS DR7 M dwarf sample with the FIRST catalog. The SDSS data allow us to examine the spectra of our objects and correlate the magnetic activity (H-alpha) with the magnetic field strength (radio emission). Accurate positions and proper motions are important for obtaining a complete list of overlapping targets. Positions in FIRST and SDSS need to be proper motion corrected in order to ensure unique target matches since nearby M dwarfs can have significant proper motions (up to 1'' per year). Some previous studies have neglected the significance of proper motions in identifying overlapping targets between SDSS and FIRST; we correct for some of these previous oversights. In addition the FIRST data were taken in multiple epochs; individual images need to be proper motion corrected before the images can be co-added. Our cross-match catalog puts important constraints on models of magnetic field generation in low-mass stars in addition to the true habitability of attending planets.

UCAC3 Proper Motion Survey. I. Discovery of New Proper Motion Stars in UCAC3 With 0.40/yr mu 0.18/yr Between Declinations -90 deg and -47 deg

DTIC Science & Technology

2010-09-01

overlooked during previous SCR and other searches. The Two-Micron All Sky Survey ( 2MASS ) was used to probe for and reduce systematic errors in UCAC CCD...of 50–200 mas, when compared to 2MASS data. For a detailed description of the derived UCAC3 proper motions see Zacharias et al. (2010). An effort was...meeting the declination and proper motion survey limits, all stars (1) must be in the 2MASS catalog with an e2mpho ( 2MASS photometry error) less than

Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. V. Final Measurement for Fornax

NASA Astrophysics Data System (ADS)

Piatek, Slawomir; Pryor, Carlton; Bristow, Paul; Olszewski, Edward W.; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

2007-03-01

The measured proper motion of Fornax, expressed in the equatorial coordinate system, is (μα,μδ)=(47.6+/-4.6,-36.0+/-4.1) mas century-1. This proper motion is a weighted mean of four independent measurements for three distinct fields. Each measurement uses a quasi-stellar object as a reference point. Removing the contribution of the motion of the Sun and of the local standard of rest to the measured proper motion produces a Galactic rest-frame proper motion of (μGrfα,μGrfδ)=(24.4+/-4.6,-14.3+/-4.1) mas century-1. The implied space velocity with respect to the Galactic center has a radial component of Vr=-31.8+/-1.7 km s-1 and a tangential component of Vt=196+/-29 km s-1. Integrating the motion of Fornax in a realistic potential for the Milky Way produces orbital elements. The perigalacticon and apogalacticon are 118 (66, 137) and 152 (144, 242) kpc, respectively, where the values in the parentheses represent the 95% confidence intervals derived from Monte Carlo experiments. The eccentricity of the orbit is 0.13 (0.11, 0.38), and the orbital period is 3.2 (2.5, 4.6) Gyr. The orbit is retrograde and inclined by 101° (94°, 107°) to the Galactic plane. Fornax could be a member of a proposed ``stream'' of galaxies and globular clusters; however, the membership of another proposed galaxy in the stream, Sculptor, has been previously ruled out. Fornax is in the Kroupa-Theis-Boily plane, which contains 11 of the Galactic satellite galaxies, but its orbit will take it out of that plane. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Using ground based data as a precursor for Gaia in getting proper motions of satellites

NASA Astrophysics Data System (ADS)

Fritz, Tobias K.; Linden, Sean T.; Zivick, Paul; Kallivayalil, Nitya; Bovy, Jo

2018-04-01

We present our effort to measure the proper motions of satellites in the halo of the Milky Way with mainly ground based telescopes as a precursor on what is possible with Gaia. For our first study, we used wide field optical data from the LBT combined with a first epoch of SDSS observations, on the globular cluster Palomar 5 (Pal 5). Since Pal 5 is associated with a tidal stream it is very useful to constrain the shape of the potential of the Milky Way. The motion and other properties of the Pal 5 system constrain the inner halo of the Milky Way to be rather spherical. Further, we combined adaptive optics and HST to get an absolute proper motion of the globular cluster Pyxis. Using the proper motion and the line-of-sight velocity we find that the orbit of Pyxis is rather eccentric with its apocenter at more than 100 kpc and its pericenter at about 30 kpc. The dynamics excludes an association with the ATLAS stream, the Magellanic clouds, and all satellites of the Milky Way at least down to the mass of Leo II. However, the properties of Pyxis, like metallicity and age, point to an origin from a dwarf of at least the mass of Leo II. We therefore propose that Pyxis originated from an unknown relatively massive dwarf galaxy, which is likely today fully disrupted. Assuming that Pyxis is bound to the Milky Way we derive a 68% lower limit on the mass of the Milky Way of 9.5 × 1011 M⊙.

A Proper Motion Search for Stars Escaping from Globular Clusters with High Velocities

NASA Astrophysics Data System (ADS)

Meusinger, H.; Scholz, R.-D.; Irwin, M.

The dynamical evolution of globular clusters, in particular during the late phases, may be strongly influenced by the energy transfer from binaries to passing stars. As a by-product of this process, stars with high velocities are expected, perhaps high enough to escape from the cluster. Accurate proper motions are the only suitable tool to identify candidates for such high-velocity cluster stars. In order to perform such a search, we use a catalogue of absolute proper motions and UBV magnitudes for about 104 stars with B < 20 in a field of 10 square degrees centered on the globular cluster M3. The data were derived from more than 80 photographic plates taken between 1965 and 1995 with the Tautenburg Schmidt telescope and measured by means of the APM facility, Cambridge. The stellar sample is complete to B = 18.5 and comprises nearly all post-main-sequence stars in the halo of M3 and its surrounding. The proper motions are of Hipparcos-like accuracy (median error 1 mas/yr) in this magnitude range. We find several dozens of candidates, distributed over the whole field, with proper motions and colours consistent with the assumption of their origin from the cluster. Further conclusions can be drawn only on the basis of radial velocity measurements for the candidates and of estimates for the field-star contamination by means of simulations of the Galactic structure and kinematics in this field.

UCAC3 PROPER MOTION SURVEY. I. DISCOVERY OF NEW PROPER MOTION STARS IN UCAC3 WITH 0.''40 yr{sup -1} > {mu} {>=} 0.''18 yr{sup -1} BETWEEN DECLINATIONS -90{sup 0} AND -47{sup 0}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Finch, Charlie T.; Zacharias, Norbert; Henry, Todd J., E-mail: finch@usno.navy.mi

2010-09-15

This paper presents 442 new proper motion stellar systems in the southern sky between declinations -90{sup 0} and -47{sup 0} with 0.''40 yr{sup -1} > {mu} {>=} 0.''18 yr{sup -1}. These systems constitute a 25.3% increase in new systems for the same region of the sky covered by previous SuperCOSMOS RECONS (SCR) searches that used Schmidt plates as the primary source of discovery. Among the new systems are 25 multiples, plus an additional 7 new common proper motion (CPM) companions to previously known primaries. All stars have been discovered using the third U.S. Naval Observatory (USNO) CCD Astrograph Catalog (UCAC3).more » A comparison of the UCAC3 proper motions to those from the Hipparcos, Tycho-2, Southern Proper Motion (SPM4), and SuperCOSMOS efforts is presented and shows that UCAC3 provides similar values and precision to the first three surveys. The comparison between UCAC3 and SuperCOSMOS indicates that proper motions in R.A. are systematically shifted in the SuperCOSMOS data but are consistent in decl. data, while overall showing a significantly higher scatter. Distance estimates are derived for stars having SuperCOSMOS Sky Survey B{sub J} , R{sub 59F}, and I{sub IVN} plate magnitudes and Two-Micron All Sky Survey infrared photometry. We find 15 systems estimated to be within 25 pc, including UPM 1710-5300 our closest new discovery estimated at 13.5 pc. Such new discoveries suggest that more nearby stars are yet to be found in these slower proper motion regimes, indicating that more work is needed to develop a complete map of the solar neighborhood.« less

VizieR Online Data Catalog: Proper motions in M 11 (Su+ 1998)

NASA Astrophysics Data System (ADS)

Su, C.-G.; Zhao, J.-L.; Tian, K.-P.

1997-07-01

Relative proper motions of 872 stars in the open cluster M 11 region are reduced using 10 plate pairs taken over time baselines of 16~70 years with the double astrograph telescope of Shanghai Observatory. The scale is 30"/mm. The plates were measured with the PDS machines in the Purple Mountain Observatory in Nanjing and the Institute of Technology and Communication in Luoyang, China. The average proper motion accuracy is about 1.1mas/yr with 85% of the data better than 1mas/yr. Membership probabilities of 785 stars within 25' centred on M 11 are determined based on their proper motions. The method used is suggested by Su et al. (1995AcApS..15..217S) with some improvements of Zhao & He (1990A&A...237...54Z), in which the space distribution and magnitude dependencies for cluster stars are taken into account. The results are significantly good. The total integrated membership probabilities for all these stars is 547 and the number of stars with probabilities higher than 0.7 is 541. It can be found after the membership determination that there exists mass segregation in M 11. Some comparisons and discussion are also given. (1 data file).

VizieR Online Data Catalog: Gaia-PS1-SDSS (GPS1) proper motion catalog (Tian+, 2017)

NASA Astrophysics Data System (ADS)

Tian, H.-J.; Gupta, P.; Sesar, B.; Rix, H.-W.; Martin, N. F.; Liu, C.; Goldman, B.; Platais, I.; Kudritzki, R.-P.; Waters, C. Z.

2018-02-01

In order to construct proper motions, we analyze and model catalog positions from four different imaging surveys, as discussed below. Gaia DR1 is based on observations collected between 2014 July 25 and 2015 September 16. PS1 observations were collected between 2010 and 2014. The SDSS DR9 data used here were obtained in the years between 2000 and 2008. The images from 2MASS were taken between 1997 and 2001. (1 data file).

Documentation for the machine-readable version of the Lowell Proper Motion Survey northern hemisphere, the G numbered stars

NASA Technical Reports Server (NTRS)

Warren, W. H., Jr.

1982-01-01

Observed positions, proper motions, estimated photographic magnitudes and colors, and references to identifications in other catalogs are included. Photoelectric data on the UBV system are included for many stars, but no attempt was made to find all existing photometry. The machine-readable catalog is described.

VizieR Online Data Catalog: New proper motion stars with pm>=0.18"/yr (Boyd+, 2011)

NASA Astrophysics Data System (ADS)

Boyd, M. R.; Henry, T. J.; Jao, W.-C.; Subasavage, J. P.; Hambly, N. C.

2012-11-01

Here we present 1584 new southern proper motion systems with μ>=0.18"/yr and 16.5>R59F>=18.0. This search complements the six previous SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky for stars within the same proper motion range, but with R59F<=16.5. As in previous papers, we present distance estimates for these systems and find that three systems are estimated to be within 25pc, including one, SCR 1546-5534, possibly within the RECONS 10pc horizon at 6.7pc, making it the second nearest discovery of the searches. We find 97 white dwarf candidates with distance estimates between 10 and 120pc, as well as 557 cool subdwarf candidates. (5 data files).

AN HST PROPER-MOTION STUDY OF THE LARGE-SCALE JET OF 3C273

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, Eileen T.; Georganopoulos, Markos; Sparks, William B.

The radio galaxy 3C 273 hosts one of the nearest and best-studied powerful quasar jets. Having been imaged repeatedly by the Hubble Space Telescope (HST) over the past twenty years, it was chosen for an HST program to measure proper motions in the kiloparsec-scale resolved jets of nearby radio-loud active galaxies. The jet in 3C 273 is highly relativistic on sub-parsec scales, with apparent proper motions up to 15c observed by very long baseline interferometry. In contrast, we find that the kiloparsec-scale knots are compatible with being stationary, with a mean speed of −0.2 ± 0.5c over the whole jet. Assuming themore » knots are packets of moving plasma, an upper limit of 1c implies a bulk Lorentz factor Γ < 2.9. This suggests that the jet has either decelerated significantly by the time it reaches the kiloparsec scale, or that the knots in the jet are standing shock features. The second scenario is incompatible with the inverse Compton off the Cosmic Microwave Background (IC/CMB) model for the X-ray emission of these knots, which requires the knots to be in motion, but IC/CMB is also disfavored in the first scenario due to energetic considerations, in agreement with the recent finding of Meyer and Georganopoulos which ruled out the IC/CMB model for the X-ray emission of 3C 273 via gamma-ray upper limits.« less

The Proper Motion of the Central Compact Object RX J0822-4300 in the Supernova Remnant Puppis A

NASA Technical Reports Server (NTRS)

Becker, Werner; Prinz, Tobias; Winkler, P. Frank; Petre, Robert

2012-01-01

Using the High Resolution Camera (HRC) aboard the Chandra X-ray Observatory, we have re-examined the proper motion of the central compact object RX J0822-4300 in the supernova remnant Puppis A. New data from 2010 August, combined with three archival data sets from as early as 1999 December, provide a baseline of 3886 days (more than 10 1/2 years) to perform the measurement. Correlating the four positions of RX J0822-4300 measured in each data set implies a projected proper motion of mu = 71 +/- 12 mas/yr. For a distance of 2 kpc this proper motion is equivalent to a recoil velocity of 672 +/- 115 km/s. The position angle is found to be 244 +/- 11 degrees. Both the magnitude and direction of the proper motion are in agreement with RX J0822-4300 originating near the optical expansion center of the supernova remnant. For a displacement of 371 +/- 31 arcsec between its birth place and today's position we deduce an age of (5.2 +/- 1.0) 10(exp 3) yrs for RX J0822-4300. The age inferred from the neutron star proper motion and filament motions can be considered as two independent measurements of the same quantity. They average to 4450 +/- 750 yrs for the age of the supernova remnant Puppis A.

VizieR Online Data Catalog: Proper motions of PM2000 open clusters (Krone-Martins+, 2010)

NASA Astrophysics Data System (ADS)

Krone-Martins, A.; Soubiran, C.; Ducourant, C.; Teixeira, R.; Le Campion, J. F.

2010-04-01

We present lists of proper-motions and kinematic membership probabilities in the region of 49 open clusters or possible open clusters. The stellar proper motions were taken from the Bordeaux PM2000 catalogue. The segregation between cluster and field stars and the assignment of membership probabilities was accomplished by applying a fully automated method based on parametrisations for the probability distribution functions and genetic algorithm optimisation heuristics associated with a derivative-based hill climbing algorithm for the likelihood optimization. (3 data files).

Photometric detection of high proper motions in dense stellar fields using difference image analysis

NASA Astrophysics Data System (ADS)

Eyer, L.; Woźniak, P. R.

2001-10-01

The difference image analysis (DIA) of the images obtained by the Optical Gravitational Lensing Experiment (OGLE-II) revealed a peculiar artefact in the sample of stars proposed as variable by Woźniak in one of the Galactic bulge fields: the occurrence of pairs of candidate variables showing anti-correlated light curves monotonic over a period of 3yr. This effect can be understood, quantified and related to the stellar proper motions. DIA photometry supplemented with a simple model offers an effective and easy way to detect high proper motion stars in very dense stellar fields, where conventional astrometric searches are extremely inefficient.

Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey

NASA Astrophysics Data System (ADS)

Skinner, Julie N.; Morgan, Dylan P.; West, Andrew A.; Lépine, Sébastien; Thorstensen, John R.

2017-09-01

We present an activity and kinematic analysis of high proper motion white dwarf-M dwarf binaries (WD+dMs) found in the SUPERBLINK survey, 178 of which are new identifications. To identify WD+dMs, we developed a UV-optical-IR color criterion and conducted a spectroscopic survey to confirm each candidate binary. For the newly identified systems, we fit the two components using model white dwarf spectra and M dwarf template spectra to determine physical parameters. We use Hα chromospheric emission to examine the magnetic activity of the M dwarf in each system, and investigate how its activity is affected by the presence of a white dwarf companion. We find that the fraction of WD+dM binaries with active M dwarfs is significantly higher than their single M dwarf counterparts at early and mid-spectral types. We corroborate previous studies that find high activity fractions at both close and intermediate separations. At more distant separations, the binary fraction appears to approach the activity fraction for single M dwarfs. Using derived radial velocities and the proper motions, we calculate 3D space velocities for the WD+dMs in SUPERBLINK. For the entire SUPERBLINK WD+dMs, we find a large vertical velocity dispersion, indicating a dynamically hotter population compared to high proper motion samples of single M dwarfs. We compare the kinematics for systems with active M dwarfs and those with inactive M dwarfs, and find signatures of asymmetric drift in the inactive sample, indicating that they are drawn from an older population. Based on observations obtained at the MDM Observatory operated by Dartmouth College, Columbia University, The Ohio State University, and the University of Michigan.

“Real-Time” Cosmology with Extragalactic Proper Motions: the Secular Aberration Drift and Evolution of Large-Scale Structure

NASA Astrophysics Data System (ADS)

Truebenbach, Alexandra; Darling, Jeremy

2018-01-01

We present the VLBA Extragalactic Proper Motion Catalog, a catalog of extragalactic proper motions created using archival VLBI data and our own VLBA astrometry. The catalog contains 713 proper motions, with average uncertainties of ~ 24 microarcsec/yr, including 40 new or improved proper motion measurements using relative astrometry with the VLBA. We detect the secular aberration drift – the apparent motion of extragalactic objects caused by the solar system's acceleration around the Galactic Center – at 6.3 sigma significance with an amplitude of 1.69 +/- 0.27 microarcsec/yr and an apex consistent with the Galactic Center (275.2 +/- 10.0 deg, -29.4 +/- 8.8 deg). Our dipole model detects the aberration drift at a higher significance than some previous studies (e.g., Titov & Lambert 2013), but at a lower amplitude than expected or previously measured. We then use the correlated relative proper motions of extragalactic objects to place upper limits on the rate of large-scale structure collapse (e.g., Quercellini et al. 2009; Darling 2013). Pairs of small separation objects that are in gravitationally interacting structures such as filaments of large-scale structure will show a net decrease in angular separation (> - 15.5 microarcsec/yr) as they move towards each other, while pairs of large separation objects that are gravitationally unbound and move with the Hubble expansion will show no net change in angular separation. With our catalog, we place a 3 sigma limit on the rate of convergence of large-scale structure of -11.4 microarcsec/yr for extragalactic objects within 100 comoving Mpc of each other. We also confirm that large separation objects (> 800 comoving Mpc) move with the Hubble flow to within ~ 2.2 microarcsec/yr. In the future, we plan to incorporate the upcoming Gaia proper motions into our catalog to achieve a higher precision measurement of the average relative proper motion of gravitationally interacting extragalactic objects and to refine our

Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. III. Measurement for Ursa Minor

NASA Astrophysics Data System (ADS)

Piatek, Slawomir; Pryor, Carlton; Bristow, Paul; Olszewski, Edward W.; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

2005-07-01

This article presents a measurement of the proper motion of the Ursa Minor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope in two distinct fields. Each field contains a quasi-stellar object that serves as the ``reference point.'' The measured proper motion for Ursa Minor, expressed in the equatorial coordinate system, is (μα,μδ)=(-50+/-17,22+/-16) mas century-1. Removing the contributions of the solar motion and the motion of the local standard of rest yields the proper motion in the Galactic rest frame: (μGrfα,μGrfδ)=(-8+/-17,38+/-16) mas century-1. The implied space velocity with respect to the Galactic center has a radial component of Vr=-75+/-44 km s-1 and a tangential component of Vt=144+/-50 km s-1. Integrating the motion of Ursa Minor in a realistic potential for the Milky Way produces orbital elements. The perigalacticon and apogalacticon are 40 (10, 76) and 89 (78, 160) kpc, respectively, where the values in the parentheses represent the 95% confidence intervals derived from Monte Carlo experiments. The eccentricity of the orbit is 0.39 (0.09, 0.79), and the orbital period is 1.5 (1.1, 2.7) Gyr. The orbit is retrograde and inclined by 124° (94°, 136°) to the Galactic plane. Ursa Minor is not a likely member of a proposed stream of galaxies on similar orbits around the Milky Way, nor is the plane of its orbit coincident with a recently proposed planar alignment of galaxies around the Milky Way. Comparing the orbits of Ursa Minor and Carina shows no reason for the different star formation histories of these two galaxies. Ursa Minor must contain dark matter to have a high probability of having survived disruption by the Galactic tidal force until the present. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

uvby photometry in McCormick proper motion fields

NASA Technical Reports Server (NTRS)

Degewij, J.

1982-01-01

The Danish 50 cm telescope at the European Southern Observatory was used to obtain high-precision uvby photometry for 50 F2 to G2 stars, with V values in the 9.4-12.3 mag range, which were selected in the southern galactic polar regions of the McCormick proper motion fields and measured on six different nights. The brighter stars are found to systematically exhibit smaller m(1) indices, of about 0.02 mag, upon comparison with the earlier data of Blaauw et al (1976). Single measurements are given for 98 stars in eight McCormick fields at intermediate southern galactic latitudes.

The Mass of the Milky Way via HST Proper Motions of Satellite Objects

NASA Astrophysics Data System (ADS)

Sohn, Sangmo Tony; van der Marel, Roeland

2018-01-01

The Universe evolves hierarchically with small structures merging and falling in to form bigger structures. Due to its proximity, the Milky Way (MW) is the best place to witness and study these hierarchical processes in action as evidenced by e.g., the many stellar streams found in MW halo. Stellar systems in the MW halo have therefore become the benchmark for testing many aspects of cosmological theories. Despite the advances in both observational and theoretical areas in the last decade or so, the total mass and mass profile of the MW still remain poorly constrained, mainly due to the limited information on the transverse motions of satellite objects in the MW halo. As part of our HSTPROMO collaboration, we have been measuring proper motions of stars, globular clusters, and satellite galaxies in the MW halo to remedy this situation. In this contribution, I will present results from our recent studies, and report our progress of ongoing projects.

A Gaia-PS1-SDSS (GPS1) Proper Motion Catalog Covering 3/4 of the Sky

NASA Astrophysics Data System (ADS)

Tian, Hai-Jun; Gupta, Prashansa; Sesar, Branimir; Rix, Hans-Walter; Martin, Nicolas F.; Liu, Chao; Goldman, Bertrand; Platais, Imants; Kudritzki, Rolf-Peter; Waters, Christopher Z.

2017-09-01

We combine Gaia DR1, PS1, Sloan Digital Sky Survey (SDSS), and 2MASS astrometry to measure proper motions for 350 million sources across three-fourths of the sky down to a magnitude of {m}r˜ 20. Using positions of galaxies from PS1, we build a common reference frame for the multi-epoch PS1, single-epoch SDSS and 2MASS data, and calibrate the data in small angular patches to this frame. As the Gaia DR1 excludes resolved galaxy images, we choose a different approach to calibrate its positions to this reference frame: we exploit the fact that the proper motions of stars in these patches are linear. By simultaneously fitting the positions of stars at different epochs of—Gaia DR1, PS1, SDSS, and 2MASS—we construct an extensive catalog of proper motions dubbed GPS1. GPS1 has a characteristic systematic error of less than 0.3 {mas} {{yr}}-1 and a typical precision of 1.5-2.0 {mas} {{yr}}-1. The proper motions have been validated using galaxies, open clusters, distant giant stars, and QSOs. In comparison with other published faint proper motion catalogs, GPS1's systematic error (< 0.3 {mas} {{yr}}-1) should be nearly an order of magnitude better than that of PPMXL and UCAC4 (> 2.0 {mas} {{yr}}-1). Similarly, its precision (˜1.5 {mas} {{yr}}-1) is a four-fold improvement relative to PPMXL and UCAC4 (˜6.0 {mas} {{yr}}-1). For QSOs, the precision of GPS1 is found to be worse (˜2.0-3.0 {mas} {{yr}}-1), possibly due to their particular differential chromatic refraction. The GPS1 catalog will be released online and be available via the VizieR Service and VO Service.

Constraining the Mass of the Local Group through Proper Motion Measurements of Local Group Galaxies

NASA Astrophysics Data System (ADS)

Sohn, S. Tony; van der Marel, R.; Anderson, J.

2012-01-01

The Local Group and its two dominant spiral galaxies have been the benchmark for testing many aspects of cosmological and galaxy formation theories. This includes, e.g., dark halo profiles and shapes, substructure and the "missing satellite" problem, and the minimum mass for galaxy formation. But despite the extensive work in all of these areas, our knowledge of the mass of the Milky Way and M31, and thus the total mass of the Local Group remains one of the most poorly established astronomical parameters (uncertain by a factor of 4). One important reason for this problem is the lack of information in tangential motions of galaxies, which can be only obtained through proper motion measurements. In this study, we introduce our projects for measuring absolute proper motions of (1) the dwarf spheroidal galaxy Leo I, (2) M31, and (3) the 4 dwarf galaxies near the edge of the Local Group (Cetus, Leo A, Tucana, and Sag DIG). Results from these three independent measurements will provide important clues to the mass of the Milky Way, M31, and the Local Group as a whole, respectively. We also present our proper motion measurement technique that uses compact background galaxies as astrometric reference sources.

Lowell proper motion survey: Southern Hemisphere (Giclas, Burnham, and Thomas 1978). Documentation for the machine-readable version

NASA Technical Reports Server (NTRS)

Warren, Wayne H., Jr.

1989-01-01

The machine-readable version of the catalog, as it is currently being distributed from the Astronomical Data Center, is described. The catalog is a summary compilation of the Lowell Proper Motion Survey for the Southern Hemisphere, as completed to mid-1978 and published in the Lowell Observatory Bulletins. This summary catalog serves as a Southern Hemisphere companion to the Lowell Proper Motion Survey, Northern Hemisphere.

Gaia Data Release 1. Astrometry: one billion positions, two million proper motions and parallaxes

NASA Astrophysics Data System (ADS)

Lindegren, L.; Lammers, U.; Bastian, U.; Hernández, J.; Klioner, S.; Hobbs, D.; Bombrun, A.; Michalik, D.; Ramos-Lerate, M.; Butkevich, A.; Comoretto, G.; Joliet, E.; Holl, B.; Hutton, A.; Parsons, P.; Steidelmüller, H.; Abbas, U.; Altmann, M.; Andrei, A.; Anton, S.; Bach, N.; Barache, C.; Becciani, U.; Berthier, J.; Bianchi, L.; Biermann, M.; Bouquillon, S.; Bourda, G.; Brüsemeister, T.; Bucciarelli, B.; Busonero, D.; Carlucci, T.; Castañeda, J.; Charlot, P.; Clotet, M.; Crosta, M.; Davidson, M.; de Felice, F.; Drimmel, R.; Fabricius, C.; Fienga, A.; Figueras, F.; Fraile, E.; Gai, M.; Garralda, N.; Geyer, R.; González-Vidal, J. J.; Guerra, R.; Hambly, N. C.; Hauser, M.; Jordan, S.; Lattanzi, M. G.; Lenhardt, H.; Liao, S.; Löffler, W.; McMillan, P. J.; Mignard, F.; Mora, A.; Morbidelli, R.; Portell, J.; Riva, A.; Sarasso, M.; Serraller, I.; Siddiqui, H.; Smart, R.; Spagna, A.; Stampa, U.; Steele, I.; Taris, F.; Torra, J.; van Reeven, W.; Vecchiato, A.; Zschocke, S.; de Bruijne, J.; Gracia, G.; Raison, F.; Lister, T.; Marchant, J.; Messineo, R.; Soffel, M.; Osorio, J.; de Torres, A.; O'Mullane, W.

2016-11-01

Context. Gaia Data Release 1 (DR1) contains astrometric results for more than 1 billion stars brighter than magnitude 20.7 based on observations collected by the Gaia satellite during the first 14 months of its operational phase. Aims: We give a brief overview of the astrometric content of the data release and of the model assumptions, data processing, and validation of the results. Methods: For stars in common with the Hipparcos and Tycho-2 catalogues, complete astrometric single-star solutions are obtained by incorporating positional information from the earlier catalogues. For other stars only their positions are obtained, essentially by neglecting their proper motions and parallaxes. The results are validated by an analysis of the residuals, through special validation runs, and by comparison with external data. Results: For about two million of the brighter stars (down to magnitude 11.5) we obtain positions, parallaxes, and proper motions to Hipparcos-type precision or better. For these stars, systematic errors depending for example on position and colour are at a level of ± 0.3 milliarcsecond (mas). For the remaining stars we obtain positions at epoch J2015.0 accurate to 10 mas. Positions and proper motions are given in a reference frame that is aligned with the International Celestial Reference Frame (ICRF) to better than 0.1 mas at epoch J2015.0, and non-rotating with respect to ICRF to within 0.03 mas yr-1. The Hipparcos reference frame is found to rotate with respect to the Gaia DR1 frame at a rate of 0.24 mas yr-1. Conclusions: Based on less than a quarter of the nominal mission length and on very provisional and incomplete calibrations, the quality and completeness of the astrometric data in Gaia DR1 are far from what is expected for the final mission products. The present results nevertheless represent a huge improvement in the available fundamental stellar data and practical definition of the optical reference frame.

Proper-Motion Study of the Magellanic Clouds Using SPM Material

DTIC Science & Technology

2010-12-01

F. VAN ALTENA I, NORBERT ZACHARIAS2, DANA I. CASETTI-DINESCU I, VLADIMIR I. KORCHAGIN I, iMANTSPLATAIS3, DAVID G. MONE -r4, CARLOS E. LOPEZ5, DAVID...difference of the two clouds to within ±54 km S-I. The absolute proper-motion results are consistent with the Clouds’ orbits being marginally bound...consistent with the Clouds’ orbits being marginally bound to the Milky Way, albeit on an elongated orbit. The inferred relative velocity between the

Outer rotation curve of the Galaxy with VERA. II. Annual parallax and proper motion of the star-forming region IRAS 21379+5106

NASA Astrophysics Data System (ADS)

Nakanishi, Hiroyuki; Sakai, Nobuyuki; Kurayama, Tomoharu; Matsuo, Mitsuhiro; Imai, Hiroshi; Burns, Ross A.; Ozawa, Takeaki; Honma, Mareki; Shibata, Katsunori M.; Kawaguchi, Noriyuki

2015-08-01

We conducted astrometric very long baseline interferometry (VLBI) observations of water-vapor maser emission in the massive star-forming region IRAS 21379+5106 in order to measure the annual parallax and proper motion, using VLBI Exploration of Radio Astrometry (VERA). The annual parallax measured 0.262 ± 0.031 mas, corresponding to a distance of 3.82^{+0.51}_{-0.41}kpc. The proper motion was (μαcos δ, μδ) = (-2.74 ± 0.08, -2.87 ± 0.18) mas yr-1. By using this result, the Galactic rotational velocity was estimated to be Vθ = 218 ± 19 km s-1 at the galactocentric distance R = 9.22 ± 0.43 kpc, when we adopted the Galactic constants R0 = 8.05 ± 0.45 kpc and V0 = 238 ± 14 km s-1. With the newly determined distance, the bolometric luminosity of the central young stellar object was reestimated to be (2.15 ± 0.54) × 103 L⊙, which corresponds to the spectral type of B2-B3. The maser features were found to be distributed along a straight line extending from the southwest to the northeast. In addition, a vector map of the internal motions, constructed from the residual proper motions, implies that the maser features trace a bipolar flow, and that it cannot be explained by simple ballistic motions.

Proper motion separation of Be stars in the Milky Way and the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Vieira, K.; García, A.; Sabogal, B.

2018-01-01

We present a proper motion investigation of a sample of Be stars candidates towards the Large Magellanic Cloud (LMC), which has resulted in the identification of two separate populations, in the Galactic foreground and in the Magellanic background. OGLE BVI and 2MASS JHK photometry were used with the SPM4 proper motions to discriminate the different populations located towards the LMC. Two populations with distinctive infrared colours and noticeable different kinematics were found, the bluer sample is consistent with being in the LMC and the redder one with belonging to the Milky Way (MW) disk. This settles the nature of the redder sample which had been described in previous publications as a possible unknown subclass of stars among the Be candidates in the LMC.

Kinematics of Local, High-Velocity K dwarfs in the SUPERBLINK Proper Motion Catalog

NASA Astrophysics Data System (ADS)

Kim, Bokyoung; Lepine, Sebastien

2018-01-01

We present a study of the kinematics of 345,480 K stars within 2 kpc of the Sun, based on data from the SUPERBLINK catalog of stars with high proper motions (> 40 mas/yr), combined with data from the 2MASS survey and from the first GAIA release, which together yields proper motions accurate to ~2 mas/yr. All K dwarfs were selected based on their G-K colors, and photometric distances were estimated from a re-calibrated color-magnitude relationship for K dwarfs. We plot transverse velocities VT in various directions on the sky, to examine the local distribution of K dwarfs in velocity space. We have also obtained radial velocity information for a subsample of 10,128 stars, from RAVE and SDSS DR12, which we use to construct spatial velocity (U, V, W) plots. About a third (123,350) of the stars are high-velocity K dwarfs, with motions consistent with the local Galactic halo population. Our kinematic analysis suggests that their velocity-space distribution is very uniform, and we find no evidence of substructure that might arise, e.g., from local streams or moving groups.

USING RUNNING DIFFERENCE IMAGES TO TRACK PROPER MOTIONS OF XUV CORONAL INTENSITY ON THE SUN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheeley, N. R. Jr.; Warren, H. P.; Lee, J., E-mail: neil.sheeley@nrl.navy.mil, E-mail: harry.warren@nrl.navy.mil

2014-12-20

We have developed a procedure for observing and tracking proper motions of faint XUV coronal intensity on the Sun and have applied this procedure to study the collective motions of cellular plumes and the shorter-period waves in sunspots. Our space/time maps of cellular plumes show a series of tracks with the same 5-8 minute repetition times and ∼100 km s{sup –1} sky-plane speeds found previously in active-region fans and in coronal hole plumes. By synchronizing movies and space/time maps, we find that the tracks are produced by elongated ejections from the unipolar flux concentrations at the bases of the cellular plumes and thatmore » the phases of these ejections are uncorrelated from cell to cell. Thus, the large-scale motion is not a continuous flow, but is more like a system of independent conveyor belts all moving in the same direction along the magnetic field. In contrast, the proper motions in sunspots are clearly waves resulting from periodic disturbances in the sunspot umbras. The periods are ∼2.6 minutes, but the sky-plane speeds and wavelengths depend on the heights of the waves above the sunspot. In the chromosphere, the waves decelerate from 35-45 km s{sup –1} in the umbra to 7-8 km s{sup –1} toward the outer edge of the penumbra, but in the corona, the waves accelerate to ∼60-100 km s{sup –1}. Because chromospheric and coronal tracks originate from the same space/time locations, the coronal waves must emerge from the same umbral flashes that produce the chromospheric waves.« less

Astrometry in the globular cluster M13. II. Membership probabilities from old proper motions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cudworth, K.

Astrometric cluster membership probabilities have been derived from proper motions measured by other authors for stars in the region of the globular cluster M13. Several stars of individual interest are discussed.

The Liverpool-Edinburgh high proper motion catalogue

NASA Astrophysics Data System (ADS)

Pokorny, R. S.; Jones, H. R. A.; Hambly, N. C.; Pinfield, D. J.

2004-07-01

We present a machine selected catalogue of 11 289 objects with proper motions exceeding 0.18 arcsec yr-1 and an R-band faint magnitude limit of 19.5 mag. The catalogue was produced using SuperCOSMOS digitized R-Band ESO and UK Schmidt Plates in 287 Schmidt fields covering almost 7000 square degrees (˜17% of the whole sky) at the South Galactic Cap. The catalogue includes UK Schmidt BJ and I magnitudes for all of the stars as well as 2MASS magnitudes for 10,447 of the catalogue stars. We also show that the NLTT is ˜95% complete for Dec > -32.5°. The full Table \\ref{tab1} is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/421/763

VizieR Online Data Catalog: VVV high proper motion stars. I. Ks<=13.5 stars (Kurtev+, 2017)

NASA Astrophysics Data System (ADS)

Kurtev, R.; Gromadzki, M.; Beamin, J. C.; Folkes, S. L.; Pena Ramirez, K.; Ivanov, V. D.; Borissova, J.; Villanueva, V.; Minniti, D.; Mendez, R.; Lucas, P. W.; Smith, L. C.; Pinfield, D. J.; Kuhn, M. A.; Jones, H. R. A.; Antonova, A.; Yip, A. K. P.

2017-05-01

A catalogue of 3003 high proper motion stars projected on the area of the Vista Variables en via Lactea NIR survey. The positions of the first and the last VVV epochs as well as the 2MASS positions of the majority of the catalogue objects are given. The catalogue also contains photometrical data for these 3003 nearby stars in ZYJHKs filters. The proper motions are calculated one using the VVV only data and VVV-2MASS positions. (2 data files).

The physical properties of double degenerate common proper motion binaries

NASA Technical Reports Server (NTRS)

Sion, Edward M.; Oswalt, Terry D.; Liebert, James; Hintzen, Paul

1991-01-01

Spectral types and spectrophotometry are presented for 21 double degenerate (DD) common proper motion binaries, along with estimates of their colors, absolute visual and bolometric magnitudes, and cooling ages. The oldest pairs in the sample are 9 x 10 to the 9th yr; the differential cooling ages range from 0.01 to 0.84. The median and mean separations of the DD pairs are 426 and 407 Au, respectively, both apparently smaller than the WD+MS values. The average UVW motions and velocity dispersions are significantly larger than the average velocities and dispersions associated with selected samples of single white dwarfs and MS+WD binaries when the latter are restricted to the same color/Mv range as the DD systems. This may be a result of the dynamical inflation of the velocity dispersion of DD systems due to their extremely ancient total stellar ages.

PROPER MOTIONS OF THE OUTER KNOTS OF THE HH 80/81/80N RADIO-JET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masqué, Josep M.; Rodriguez, Luis F.; Carrasco-González, Carlos

2015-11-20

The radio-knots of the Herbig–Haro (HH) 80/81/80N jet extend from the HH 80 object to the recently discovered Source 34 and has a total projected jet size of 10.3 pc, constituting the largest collimated radio-jet system known so far. It is powered by the bright infrared source IRAS 18162−2048 associated with a massive young stellar object. We report 6 cm JVLA observations that, compared with previous 6 cm VLA observations carried out in 1989, allow us to derive proper motions of the HH 80, HH 81, and HH 80N radio knots located about 2.5 pc away in projection from themore » powering source. For the first time, we measure proper motions of the optically obscured HH 80N object providing evidence that this knot, along with HH 81 and HH 80 are associated with the same radio-jet. We also confirm the presence of Source 34, located further north of HH 80N, previously proposed to belong to the jet.We derived that the tangential velocity of HH 80N is 260 km s{sup −1} and has a direction in agreement with the expected direction of a ballistic precessing jet. The HH 80 and HH 81 objects have tangential velocities of 350 and 220 km s{sup −1}, respectively, but their directions are somewhat deviated from the expected jet path. The velocities of the HH objects studied in this work are significantly lower than those derived for the radio knots of the jet close to the powering source (600–1400 km s{sup −1}) suggesting that the jet is slowing down due to a strong interaction with the ambient medium. As a result, since HH 80 and HH 81 are located near the edge of the cloud, the inhomogeneous and low density medium may contribute to skew the direction of their determined proper motions. The HH 80 and HH 80N emission at 6 cm is, at least in part, probably synchrotron radiation produced by relativistic electrons in a magnetic field of 1 mG. If these electrons are accelerated in a reverse adiabatic shock, we estimate a jet total density of ≲1000 cm{sup −3}. All of these

Proper motions of collimated jets from intermediate-mass protostars in the Carina Nebula

NASA Astrophysics Data System (ADS)

Reiter, Megan; Kiminki, Megan M.; Smith, Nathan; Bally, John

2017-10-01

We present proper motion measurements of 37 jets and HH objects in the Carina Nebula measured in two epochs of H α images obtained ˜10 yr apart with Hubble Space Telescope/Advanced Camera for Surveys (ACS). Transverse velocities in all but one jet are faster than ≳ 25 km s-1, confirming that the jet-like H α features identified in the first epoch images trace outflowing gas. Proper motions constrain the location of the jet-driving source and provide kinematic confirmation of the intermediate-mass protostars that we identify for 20/37 jets. Jet velocities do not correlate with the estimated protostar mass and embedded driving sources do not have slower jets. Instead, transverse velocities (median ˜75 km s-1) are similar to those in jets from low-mass stars. Assuming a constant velocity since launch, we compute jet dynamical ages (median ˜104 yr). If continuous emission from inner jets traces the duration of the most recent accretion bursts, then these episodes are sustained longer (median ˜700 yr) than the typical decay time of an FU Orionis outburst. These jets can carry appreciable momentum that may be injected into the surrounding environment. The resulting outflow force, dP/dt, lies between that measured in low- and high-mass sources, despite the very different observational tracers used. Smooth scaling of the outflow force argues for a common physical process underlying outflows from protostars of all masses. This latest kinematic result adds to a growing body of evidence that intermediate-mass star formation proceeds like a scaled-up version of the formation of low-mass stars.

VizieR Online Data Catalog: 1103 parallaxes and proper motions from URAT (Finch+, 2016)

NASA Astrophysics Data System (ADS)

Finch, C. T.; Zacharias, N.

2016-07-01

We present 1103 trigonometric parallaxes and proper motions from the United States Naval Observatory (USNO) Robotic Astrometric Telescope (URAT) observations taken at the Naval Observatory Flagstaff Station (NOFS). URAT observes through a single filter (part of the dewar window) to provide a fixed bandpass of about 680 to 760nm. The clear aperture of the USNO astrograph is 206mm with a focal length of only 2m. A single exposure covers 28 square degrees with a resolution of 0.9arcsec/pixel. Each of the four large CCDs in the focal plane covers a 2.65 by 2.65 deg area on the sky. Data of all three years of operations (2012 April to 2015 June) at the NOFS are used here for this parallax investigation. For more details about the project, instrument, and observing the reader is referred to the URAT1 paper (Zacharias et al. 2015, cat. I/329). (3 data files).

A method for determining the radius of an open cluster from stellar proper motions

NASA Astrophysics Data System (ADS)

Sánchez, Néstor; Alfaro, Emilio J.; López-Martínez, Fátima

2018-04-01

We propose a method for calculating the radius of an open cluster in an objective way from an astrometric catalogue containing, at least, positions and proper motions. It uses the minimum spanning tree in the proper motion space to discriminate cluster stars from field stars and it quantifies the strength of the cluster-field separation by means of a statistical parameter defined for the first time in this paper. This is done for a range of different sampling radii from where the cluster radius is obtained as the size at which the best cluster-field separation is achieved. The novelty of this strategy is that the cluster radius is obtained independently of how its stars are spatially distributed. We test the reliability and robustness of the method with both simulated and real data from a well-studied open cluster (NGC 188), and apply it to UCAC4 data for five other open clusters with different catalogued radius values. NGC 188, NGC 1647, NGC 6603, and Ruprecht 155 yielded unambiguous radius values of 15.2 ± 1.8, 29.4 ± 3.4, 4.2 ± 1.7, and 7.0 ± 0.3 arcmin, respectively. ASCC 19 and Collinder 471 showed more than one possible solution, but it is not possible to know whether this is due to the involved uncertainties or due to the presence of complex patterns in their proper motion distributions, something that could be inherent to the physical object or due to the way in which the catalogue was sampled.

The SUPERBLINK catalog of stars with large proper motions, with enhancements from the first GAIA release.

NASA Astrophysics Data System (ADS)

Lepine, Sebastien

2018-01-01

The SUPERBLINK survey of stars with proper motion larger than 40 mas/yr is now complete for the entire sky down to magnitude V=20. The SUPERBLINK catalog provides astrometric and photometric data for a little over 2.7 million individual stars, and identifies their counterparts in a variety of large catalogs including ROSAT in the X-ray, GALEX in the ultraviolet, GAIA and SDSS in the optical, and 2MASS and WISE in the infrared. The addition of GAIA data notably yields proper motions to an accuracy of ~2mas/yr for 94% of the entries. Parallaxes with accuracies better than 10% are also now available for about 155,000 of these stars. Besides from identifying local populations of low-mass stars and white dwarfs, the catalog nows begins to map out with some detail the distribution in velocity space of various local stellar populations, including young M dwarfs and old metal-poor M subdwarfs. The catalog also allows one to search for common proper motion pairs, and other kinematic groups like nearby cluster members, moving group members, and local streams. This demonstrates the potential for nearby star research as more complete data becomes available from the GAIA mission.

A SUBSTELLAR COMMON PROPER-MOTION COMPANION TO THE PLEIAD H II 1348

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geissler, Kerstin; Metchev, Stanimir A.; Pham, Alfonse

2012-02-10

We announce the identification of a proper-motion companion to the star H II 1348, a K5 V member of the Pleiades open cluster. The existence of a faint point source 1.''1 away from H II 1348 was previously known from adaptive optics imaging by Bouvier et al. However, because of a high likelihood of background star contamination and in the absence of follow-up astrometry, Bouvier et al. tentatively concluded that the candidate companion was not physically associated with H II 1348. We establish the proper-motion association of the pair from adaptive optics imaging with the Palomar 5 m telescope. Adaptivemore » optics spectroscopy with the integral field spectrograph OSIRIS on the Keck 10 m telescope reveals that the companion has a spectral type of M8 {+-} 1. According to substellar evolution models, the M8 spectral type resides within the substellar mass regime at the age of the Pleiades. The primary itself is a known double-lined spectroscopic binary, which makes the resolved companion, H II 1348B, the least massive and widest component of this hierarchical triple system and the first substellar companion to a stellar primary in the Pleiades.« less

Four years experience in APMS star plate processing - Results and future plans. [Automated Proper Motion Study

NASA Technical Reports Server (NTRS)

Newcomb, J. S.

1975-01-01

The present paper describes an automated system for measuring stellar proper motions on the basis of information contained in photographic plates. In this system, the images on a star plate are digitized by a scanning microdensitometer using light from a He-Ne gas laser, and a special-purpose computer arranges the measurements in computer-compatible form on magnetic tape. The scanning and image-reconstruction processes are briefly outlined, and the image-evaluation techniques are discussed. It is shown that the present system has been especially successful in measuring the proper motions of low-luminosity stars, including 119 stars with less than 1/10,000 of the solar bolometric luminosity. Plans for measurements of high-density Milky Way star plates are noted.

Proper Motions and Structural Parameters of the Galactic Globular Cluster M71

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cadelano, M.; Dalessandro, E.; Ferraro, F. R.

2017-02-20

By exploiting two ACS/ HST data sets separated by a temporal baseline of ∼7 years, we have determined the relative stellar proper motions (PMs; providing membership) and the absolute PM of the Galactic globular cluster M71. The absolute PM has been used to reconstruct the cluster orbit within a Galactic, three-component, axisymmetric potential. M71 turns out to be in a low-latitude disk-like orbit inside the Galactic disk, further supporting the scenario in which it lost a significant fraction of its initial mass. Since large differential reddening is known to affect this system, we took advantage of near-infrared, ground-based observations tomore » re-determine the cluster center and density profile from direct star counts. The new structural parameters turn out to be significantly different from the ones quoted in the literature. In particular, M71 has a core and a half-mass radii almost 50% larger than previously thought. Finally, we estimate that the initial mass of M71 was likely one order of magnitude larger than its current value, thus helping to solve the discrepancy with the observed number of X-ray sources.« less

ON THE CONNECTION OF THE APPARENT PROPER MOTION AND THE VLBI STRUCTURE OF COMPACT RADIO SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moor, A.; Frey, S.; Lambert, S. B.

2011-06-15

Many of the compact extragalactic radio sources that are used as fiducial points to define the celestial reference frame are known to have proper motions detectable with long-term geodetic/astrometric very long baseline interferometry (VLBI) measurements. These changes can be as high as several hundred microarcseconds per year for certain objects. When imaged with VLBI at milliarcsecond (mas) angular resolution, these sources (radio-loud active galactic nuclei) typically show structures dominated by a compact, often unresolved 'core' and a one-sided 'jet'. The positional instability of compact radio sources is believed to be connected with changes in their brightness distribution structure. For themore » first time, we test this assumption in a statistical sense on a large sample rather than on only individual objects. We investigate a sample of 62 radio sources for which reliable long-term time series of astrometric positions as well as detailed 8 GHz VLBI brightness distribution models are available. We compare the characteristic direction of their extended jet structure and the direction of their apparent proper motion. We present our data and analysis method, and conclude that there is indeed a correlation between the two characteristic directions. However, there are cases where the {approx}1-10 mas scale VLBI jet directions are significantly misaligned with respect to the apparent proper motion direction.« less

The Systemic Proper Motions of the Magellanic Clouds and their Orbits around the Milky Way

NASA Astrophysics Data System (ADS)

Kallivayalil, N.; van der Marel, R. P.; Alcock, C.; Axelrod, T.; Cook, K. H.; Drake, A. J.; Geha, M.

2005-12-01

The interaction between the Large and Small Magellanic Clouds (LMC & SMC) and the Milky Way (MW) is thought to have played an important role in the dynamical evolution of the MW's outer parts. The Clouds probe the potential of the MW dark halo in places where other kinematic tracers are unavailable and thus the MW-MC system has been a major subject of study. In particular, the global dynamics of both Clouds need to be well prescribed before other evolutionary features of the system can be understood. The radial velocities of the clouds are more readily determined than the transverse velocities, which can only be estimated using proper motions. We undertook a project using two epochs of HST/ACS data to determine the systemic proper motions of the Clouds. The Magellanic Cloud fields are centered on background QSOs that were discovered from their optical variability in the MACHO database (Geha et al. 2003). The final sample consists of 21 QSOs behind the LMC and 5 behind the SMC, distributed homogeneously behind the central few degrees of both Clouds. With a ˜2 year baseline and the use of the High Resolution Camera, we have determined the proper motion of the LMC to better than 5 \\ μ N = 0.44 ± 0.05 mas/yr (Kallivayalil et al. 2005). This is the most accurate proper motion measurement for any MW satellite thus far. We will present this measurement, as well as our results for the SMC, and the conclusions we can draw about the Clouds' orbits around the MW. Our study shows that ground-based work on finding QSOs can be combined with high resolution HST data to get good measurements in a relatively short amount of time. When combined with HI data from the Magellanic Stream our measurements should provide new constraints on both the mass distribution of the Galactic Halo and models of the Stream. Support for this work was provided by NASA through grant numbers GO-09462 and GO-10130 from STScI. KHC's work was performed under the auspices of the U.S. DOE, NNSA, by the

Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skinner, Julie N.; Morgan, Dylan P.; West, Andrew A.

We present an activity and kinematic analysis of high proper motion white dwarf-M dwarf binaries (WD+dMs) found in the SUPERBLINK survey, 178 of which are new identifications. To identify WD+dMs, we developed a UV–optical–IR color criterion and conducted a spectroscopic survey to confirm each candidate binary. For the newly identified systems, we fit the two components using model white dwarf spectra and M dwarf template spectra to determine physical parameters. We use H α chromospheric emission to examine the magnetic activity of the M dwarf in each system, and investigate how its activity is affected by the presence of amore » white dwarf companion. We find that the fraction of WD+dM binaries with active M dwarfs is significantly higher than their single M dwarf counterparts at early and mid-spectral types. We corroborate previous studies that find high activity fractions at both close and intermediate separations. At more distant separations, the binary fraction appears to approach the activity fraction for single M dwarfs. Using derived radial velocities and the proper motions, we calculate 3D space velocities for the WD+dMs in SUPERBLINK. For the entire SUPERBLINK WD+dMs, we find a large vertical velocity dispersion, indicating a dynamically hotter population compared to high proper motion samples of single M dwarfs. We compare the kinematics for systems with active M dwarfs and those with inactive M dwarfs, and find signatures of asymmetric drift in the inactive sample, indicating that they are drawn from an older population.« less

A Common Proper Motion Stellar Companion to HAT-P-7

NASA Technical Reports Server (NTRS)

Grady, Carol A.; McElwain, Michael W.; Narita, Norio; Takahashi, Yasuhiro H.; Kuzuhara, Masayuki; Hirano, Teruyuki; Suenaga, Takuya

2012-01-01

We report that HAT-P-7 has a common proper motion stellar companion. The companion is located at approx. 3.9 arcsec to the east and estimated as an M5.5V dwarf based on its colors. We also confirm the presence of the third companion, which was first reported by Winn et al. (2009), based on long-term radial velocity measurements. We revisit the migration mechanism of HAT-P-7b given the presence of those companions, and propose sequential Kozai migration as a likely scenario in this system. This scenario may explain the reason for an outlier in the discussion of the spin-orbit alignment timescale for HAT-P-7b by Albrecht et al. (2012).

The Solar Neighborhood. XXV. Discovery of New Proper Motion Stars with 0.40 sec/yr mu or = 0.18 sec/yr Between Declinations -47 deg and 00 deg

DTIC Science & Technology

2011-07-01

that the object was indeed a proper motion object. For real ob- jects, Two Micron All Sky Survey ( 2MASS ) positions, epochs, and JHKs photometry were...and vice versa, and to ensure the correct 2MASS data were collected. The blinking process led to the discovery of many common proper motion (CPM...Proper motion or position angle suspect. f No 2MASS data available, so no distance estimate. g Coordinates not J2000.0 due to lack of proper motion or

Proper Motions and Structural Parameters of the Galactic Globular Cluster M71

NASA Astrophysics Data System (ADS)

Cadelano, M.; Dalessandro, E.; Ferraro, F. R.; Miocchi, P.; Lanzoni, B.; Pallanca, C.; Massari, D.

2017-02-01

By exploiting two ACS/HST data sets separated by a temporal baseline of ˜7 years, we have determined the relative stellar proper motions (PMs; providing membership) and the absolute PM of the Galactic globular cluster M71. The absolute PM has been used to reconstruct the cluster orbit within a Galactic, three-component, axisymmetric potential. M71 turns out to be in a low-latitude disk-like orbit inside the Galactic disk, further supporting the scenario in which it lost a significant fraction of its initial mass. Since large differential reddening is known to affect this system, we took advantage of near-infrared, ground-based observations to re-determine the cluster center and density profile from direct star counts. The new structural parameters turn out to be significantly different from the ones quoted in the literature. In particular, M71 has a core and a half-mass radii almost 50% larger than previously thought. Finally, we estimate that the initial mass of M71 was likely one order of magnitude larger than its current value, thus helping to solve the discrepancy with the observed number of X-ray sources. Based on observations collected with the NASA/ESA HST (GO10775, GO12932), obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.

Proper motion separation of Be star candidates in the Magellanic Clouds and the Milky Way

NASA Astrophysics Data System (ADS)

Vieira, Katherine; García-Varela, Alejandro; Sabogal, Beatriz

2017-08-01

We present a proper motion investigation of a sample of Be star candidates towards the Magellanic Clouds, which has resulted in the identification of separate populations, in the Galactic foreground and in the Magellanic background. Be stars are broadly speaking B-type stars that have shown emission lines in their spectra. In this work, we studied a sample of 2446 and 1019 Be star candidates towards the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), respectively, taken from the literature and proposed as possible Be stars due to their variability behaviour in the OGLE-II I band. JHKs magnitudes from the InfraRed Survey Facility catalogue and proper motions from the Southern Proper Motion 4 catalogue were obtained for 1188 and 619 LMC and SMC Be stars candidates, respectively. Colour-colour and vector-point diagrams were used to identify different populations amongst the Be star candidates. In the LMC sample, two populations with distinctive infrared colours and kinematics were found, the bluer sample is consistent with being in the LMC and the redder one with belonging to the Milky Way disc. This settles the nature of the redder sample that had been described in previous publications as a possible unknown subclass of stars amongst the Be candidates in the LMC. In the SMC sample, a similar but less evident result was obtained, since this apparent unknown subclass was not seen in this galaxy. We confirm that in the selection of Be stars by their variability, although generally successful, there is a higher risk of contamination by Milky Way objects towards redder B - V and V - I colours.

New Common Proper-Motion Pairs with R.A. Between 00h and 01h

NASA Astrophysics Data System (ADS)

Caballero, Rafael

2015-07-01

This paper presents 37 new common proper-motion pairs. The new pairs have been obtained employing a semi-automatic procedure based on the inspection of images using the tool Aladin, completed with information obtained from the catalogs available at VizieR. All the pairs fulfill the Halbwachs criteria, employed to increase the probability of a physical bond between the two components.

The M31 Velocity Vector. I. Hubble Space Telescope Proper-motion Measurements

NASA Astrophysics Data System (ADS)

Sohn, Sangmo Tony; Anderson, Jay; van der Marel, Roeland P.

2012-07-01

We present the first proper-motion (PM) measurements for the galaxy M31. We obtained new V-band imaging data with the Hubble Space Telescope ACS/WFC and the WFC3/UVIS instruments of three fields: a spheroid field near the minor axis, an outer disk field along the major axis, and a field on the Giant Southern Stream. The data provide five to seven year time baselines with respect to pre-existing deep first-epoch observations of the same fields. We measure the positions of thousands of M31 stars and hundreds of compact background galaxies in each field. High accuracy and robustness is achieved by building and fitting a unique template for each individual object. The average PM for each field is obtained from the average motion of the M31 stars between the epochs with respect to the background galaxies. For the three fields, the observed PMs (μ W , μ N ) are, in units of mas yr-1, (- 0.0458, -0.0376) ± (0.0165, 0.0154), (- 0.0533, -0.0104) ± (0.0246, 0.0244), and (- 0.0179, -0.0357) ± (0.0278, 0.0272), respectively. The ability to average over large numbers of objects and over the three fields yields a final displacement accuracy of a few thousandths of a pixel, corresponding to only 12 μas yr-1. This is comparable to what has been achieved for other Local Group galaxies using Very Long Baseline Array observations of water masers. Potential systematic errors are controlled by an analysis strategy that corrects for detector charge transfer inefficiency, spatially and time-dependent geometric distortion, and point-spread function variations. The robustness of the PM measurements and uncertainties are supported by the fact that data from different instruments, taken at different times and with different telescope orientations, as well as measurements of different fields, all yield statistically consistent results. Papers II and III of this series explore the implications of the new measurements for our understanding of the history, future, and mass of the Local

PROPER MOTIONS AND ORIGINS OF SGR 1806-20 AND SGR 1900+14

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tendulkar, Shriharsh P.; Kulkarni, Shrinivas R.; Cameron, P. Brian, E-mail: spt@astro.caltech.edu

2012-12-10

We present results from high-resolution infrared observations of magnetars SGR 1806-20 and SGR 1900+14 over 5 years using laser-supported adaptive optics at the 10 m Keck Observatory. Our measurements of the proper motions of these magnetars provide robust links between magnetars and their progenitors and provide age estimates for magnetars. At the measured distances of their putative associations, we measure the linear transverse velocity of SGR 1806-20 to be 350 {+-} 100 km s{sup -1} and of SGR 1900+14 to be 130 {+-} 30 km s{sup -1}. The transverse velocity vectors for both magnetars point away from the clusters ofmore » massive stars, solidifying their proposed associations. Assuming that the magnetars were born in the clusters, we can estimate the braking index to be {approx}1.8 for SGR 1806-20 and {approx}1.2 for SGR 1900+14. This is significantly lower than the canonical value of n = 3 predicted by the magnetic dipole spin-down suggesting an alternative source of dissipation such as twisted magnetospheres or particle winds.« less

PG1258+593 and its common proper motion magnetic white dwarf counterpart

NASA Astrophysics Data System (ADS)

Girven, J.; Gänsicke, B. T.; Külebi, B.; Steeghs, D.; Jordan, S.; Marsh, T. R.; Koester, D.

2010-05-01

We confirm SDSSJ130033.48+590407.0 as a common proper motion companion to the well-studied hydrogen-atmosphere (DA) white dwarf PG1258+593 (GD322). The system lies at a distance of 68 +/- 3pc, where the angular separation of 16.1 +/- 0.1arcsec corresponds to a minimum binary separation of 1091 +/- 7au. SDSSJ1300+5904 is a cool (Teff = 6300 +/- 300K) magnetic white dwarf (B ~= 6mG). PG1258+593 is a DA white dwarf with Teff = 14790 +/- 77K and logg = 7.87 +/- 0.02. Using the white dwarf mass-radius relation implies the masses of SDSSJ1300+5904 and PG1258+593 are 0.54 +/- 0.06 and 0.54 +/- 0.01Msolar, respectively, and therefore a cooling age difference of 1.67 +/- 0.05Gyr. Adopting main-sequence lifetimes from stellar models, we derive an upper limit of 2.2Msolar for the mass of the progenitor of PG1258+593. A plausible range of initial masses is 1.4-1.8 Msolar for PG1258+593 and 2-3 Msolar for SDSSJ1300+5904. Our analysis shows that white dwarf common proper motion binaries can potentially constrain the white dwarf initial mass-final mass relation and the formation mechanism for magnetic white dwarfs. The magnetic field of SDSSJ1300+5904 is consistent with an Ap progenitor star. A common envelope origin of the system cannot be excluded, but requires a triple system as progenitor.

Documentation for the machine-readable version of the Lowell Proper Motion Survey, Northern Hemisphere, the G numbered stars

NASA Technical Reports Server (NTRS)

Warren, W. H., Jr.

1983-01-01

This catalog contains a summary of many individual papers published in the Lowell Observatory Bulletins in the years 1958 to 1970. The data in the machine-readable version include observed positions, proper motions, estimated photographic magnitudes and colors, and references to identifications in other catalogs. Photoelectric data on the UBV system are included for many stars, but no attempt was made to find all existing photometry. The machine version contains all data of the published catalog, except the Lowell Bulletin numbers where finding charts can be found. A separate file contains the notes published in the original catalog.

Cygnus OB2 DANCe: A high-precision proper motion study of the Cygnus OB2 association

NASA Astrophysics Data System (ADS)

Wright, Nicholas J.; Bouy, Herve; Drew, Janet E.; Sarro, Luis Manuel; Bertin, Emmanuel; Cuillandre, Jean-Charles; Barrado, David

2016-08-01

We present a high-precision proper motion study of 873 X-ray and spectroscopically selected stars in the massive OB association Cygnus OB2 as part of the DANCe project. These were calculated from images spanning a 15 yr baseline and have typical precisions <1 mas yr-1. We calculate the velocity dispersion in the two axes to be σ _α (c) = 13.0^{+0.8}_{-0.7} and σ _δ (c) = 9.1^{+0.5}_{-0.5} km s-1, using a two-component, two-dimensional model that takes into account the uncertainties on the measurements. This gives a three-dimensional velocity dispersion of σ3D = 17.8 ± 0.6 km s-1 implying a virial mass significantly larger than the observed stellar mass, confirming that the association is gravitationally unbound. The association appears to be dynamically unevolved, as evidenced by considerable kinematic substructure, non-isotropic velocity dispersions and a lack of energy equipartition. The proper motions show no evidence for a global expansion pattern, with approximately the same amount of kinetic energy in expansion as there is in contraction, which argues against the association being an expanded star cluster disrupted by process such as residual gas expulsion or tidal heating. The kinematic substructures, which appear to be close to virial equilibrium and have typical masses of 40-400 M⊙, also do not appear to have been affected by the expulsion of the residual gas. We conclude that Cyg OB2 was most likely born highly substructured and globally unbound, with the individual subgroups born in (or close to) virial equilibrium, and that the OB association has not experienced significant dynamical evolution since then.

New High Proper Motion Stars from the Digitized Sky Survey. II. Northern Stars with 0.5" yr-1 < μ < 2.0" yr-1 at High Galactic Latitudes

NASA Astrophysics Data System (ADS)

Lépine, Sébastien; Shara, Michael M.; Rich, R. Michael

2003-08-01

In a continuation of our systematic search for high proper motion stars in the Digitized Sky Survey, we have completed the analysis of northern sky fields at Galactic latitudes above 25°. With the help of our SUPERBLINK software, a powerful automated blink comparator developed by us, we have identified 1146 stars in the magnitude range 8proper motions 0.500"yr-1<μ<2.000"yr-1. These include 1080 stars previously listed in Luyten's proper-motion catalogs (the Luyten Half-Second catalog and the New Luyten Two-Tenths catalog), nine stars not previously listed in the Luyten catalogs but reported elsewhere in the literature (including one previously reported by our team), and 57 new objects reported here for the first time. This paper includes a list of positions, proper motions, magnitudes, and finder charts for all the new high proper motion stars. Combined with our previous study of low Galactic latitude fields (see Paper I), our survey now covers over 98% of the northern sky. We conclude that the Luyten catalogs were ~=90% complete in the northern sky for stars with 0.5"<μ<2.0" down to magnitude r=19. We discuss the incompleteness of the old Luyten proper-motion survey and estimate completeness limits for our new survey. Based on data mining of the Digitized Sky Survey, developed and operated by the Catalogs and Surveys Branch of the Space Telescope Science Institute, Baltimore.

Measurement of the X-Ray Proper Motion in the South-East Rim of RXJ1713.7-3946

NASA Technical Reports Server (NTRS)

Acero, Fabio; Katsuda, Saturo; Ballet, Jean; Petre, Robert

2017-01-01

We report on the first proper motion measurement in the supernova remnant RX J1713.73946 using the XMM-Newton X-ray telescope on a 13 yr time interval. This expansion measurement is carried out in the south-east region of the remnant, where two sharp filament structures are observed. For the outermost filament, the proper motion is 0.75(+0.05-0.06) +/- 0.069 syst arcsec/ yr which is equivalent to a shock speed of approx. 3500 km/s at a distance of 1 kpc. In contrast with the bright north-west region, where the shock is interacting with the border of the cavity, the shock in the south-east region is probably expanding in the original ambient medium carved by the progenitor and can be used to derive the current density at the shock and the age of the remnant. In the case where the shock is evolving in a wind profile (p varies as r(sup -s), s = 2) or in a uniform medium (s = 0), we estimate an age of approx. 2300 yr and approx.1800 yr respectively for an ejecta power-law index of n = 9. The specific case of an ejecta power-law index of n = 7, and s = 0, yields an age of approx. 1500 yr, which would reconcile RX J1713.73946 with the historical records of SN 393. In all scenarios, we derive similar upstream densities of the order of 0.01/cu cm, compatible with the lack of thermal X-rays from the shocked ambient medium.

Fundamental Principles of Proper Space Kinematics

NASA Astrophysics Data System (ADS)

Wade, Sean

It is desirable to understand the movement of both matter and energy in the universe based upon fundamental principles of space and time. Time dilation and length contraction are features of Special Relativity derived from the observed constancy of the speed of light. Quantum Mechanics asserts that motion in the universe is probabilistic and not deterministic. While the practicality of these dissimilar theories is well established through widespread application inconsistencies in their marriage persist, marring their utility, and preventing their full expression. After identifying an error in perspective the current theories are tested by modifying logical assumptions to eliminate paradoxical contradictions. Analysis of simultaneous frames of reference leads to a new formulation of space and time that predicts the motion of both kinds of particles. Proper Space is a real, three-dimensional space clocked by proper time that is undergoing a densification at the rate of c. Coordinate transformations to a familiar object space and a mathematical stationary space clarify the counterintuitive aspects of Special Relativity. These symmetries demonstrate that within the local universe stationary observers are a forbidden frame of reference; all is in motion. In lieu of Quantum Mechanics and Uncertainty the use of the imaginary number i is restricted for application to the labeling of mass as either material or immaterial. This material phase difference accounts for both the perceived constant velocity of light and its apparent statistical nature. The application of Proper Space Kinematics will advance more accurate representations of microscopic, oscopic, and cosmological processes and serve as a foundation for further study and reflection thereafter leading to greater insight.

A Proper Motions Study of the Globular Cluster NGC 3201

NASA Astrophysics Data System (ADS)

Sariya, Devesh P.; Jiang, Ing-Guey; Yadav, R. K. S.

2017-03-01

With a high value of heliocentric radial velocity, a retrograde orbit, and suspected to have an extragalactic origin, NGC 3201 is an interesting globular cluster for kinematical studies. Our purpose is to calculate the relative proper motions (PMs) and membership probability for the stars in the wide region of globular cluster NGC 3201. PM based membership probabilities are used to isolate the cluster sample from the field stars. The membership catalog will help address the question of chemical inhomogeneity in the cluster. Archive CCD data taken with a wide-field imager (WFI) mounted on the ESO 2.2 m telescope are reduced using the high-precision astrometric software developed by Anderson et al. for the WFI images. The epoch gap between the two observational runs is ˜14.3 years. To standardize the BVI photometry, Stetson’s secondary standard stars are used. The CCD data with an epoch gap of ˜14.3 years enables us to decontaminate the cluster stars from field stars efficiently. The median precision of PMs is better than ˜0.8 mas yr-1 for stars having V< 18 mag that increases up to ˜1.5 mas yr-1 for stars with 18< V< 20 mag. Kinematic membership probabilities are calculated using PMs for stars brighter than V˜ 20 mag. An electronic catalog of positions, relative PMs, BVI magnitudes, and membership probabilities in the ˜19.7 × 17 arcmin2 region of NGC 3201 is presented. We use our membership catalog to identify probable cluster members among the known variables and X-ray sources in the direction of NGC 3201. Based on observations with the MPG/ESO 2.2 m and ESO/VLT telescopes, located at La Silla and Paranal Observatory, Chile, under DDT programs 164.O-0561(F), 093.A-9028(A), and the archive material.

Measurement of the X-ray proper motion in the south-east rim of RX J1713.7-3946

NASA Astrophysics Data System (ADS)

Acero, Fabio; Katsuda, Satoru; Ballet, Jean; Petre, Robert

2017-01-01

We report on the first proper motion measurement in the supernova remnant RX J1713.7-3946 using the XMM-Newton X-ray telescope on a 13 yr time interval. This expansion measurement is carried out in the south-east region of the remnant, where two sharp filament structures are observed. For the outermost filament, the proper motion is arcsec yr-1 which is equivalent to a shock speed of 3500 km s-1 at a distance of 1 kpc. In contrast with the bright north-west region, where the shock is interacting with the border of the cavity, the shock in the south-east region is probably expanding in the original ambient medium carved by the progenitor and can be used to derive the current density at the shock and the age of the remnant. In the case where the shock is evolving in a wind profile (ρ ∝ r- s, s = 2) or in a uniform medium (s = 0), we estimate an age of 2300 yr and 1800 yr respectively for an ejecta power-law index of n = 9. The specific case of an ejecta power-law index of n = 7, and s = 0, yields an age of 1500 yr, which would reconcile RX J1713.7-3946 with the historical records of SN 393. In all scenarios, we derive similar upstream densities of the order of 0.01 cm-3, compatible with the lack of thermal X-rays from the shocked ambient medium.

VizieR Online Data Catalog: WD+dMs from the SUPERBLINK proper motion survey (Skinner+, 2017)

NASA Astrophysics Data System (ADS)

Skinner, J. N.; Morgan, D. P.; West, A. A.; Lepine, S.; Thorstensen, J. R.

2018-06-01

To select for nearby WD+dMs, we used the SUPERBLINK proper motion survey (Lepine et al. 2002, J/AJ/124/1190; Lepine & Shara 2005, Cat. I/298), an ongoing all-sky survey that identifies and characterizes stars with proper motions μ>40 mas/yr. For this study, we used the 2011 July version of SUPERBLINK, which listed 2270481 stars, and was estimated to be >90% complete to V=19.0. We selected WD+dMs based on a combination of V magnitudes derived from the DSS plates (see Lepine & Shara 2005, Cat. I/298), near-UV magnitudes from GALEX, and Ks magnitudes from 2MASS. Using the UV-optical-IR color selection outlined in Skinner et al. (2014AJ....148..115S), we selected targets for spectroscopic follow-up (see bottom panel of Figure 1). We acquired optical spectroscopy of 178 newly identified WD+dM candidates, with the Boller and Chivens CCD spectrograph (CCDS), using both the Hiltner 2.4 m and McGraw-Hill 1.3 m telescopes located at the MDM Observatory. (3 data files).

Determination of the masses of globular clusters using proper motions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ninkovich, S.

1984-09-01

Published proper motions of stars in the fields of the globular clusters M 15, M 92, and M 13 (Cudworth, 1976 Cudworth and Monet, 1979) are compiled in tables and used to estimate the masses of the clusters by the method of Naumova and Ogorodnikov (1973). Masses of the order of 10 to the 8th solar mass are calculated, as compared to an M 13 mass of about 10 to the 6th solar mass determined by the virial theorem. The higher masses are considered indicative of the actual cluster masses despite the distortion introduced by the presence in the fieldmore » of stars not belonging to the clusters. It is suggested that the difference between these estimates and the smaller masses proposed by previous authors may represent unobservable peripheral dwarf stars or some invisible mass (like the so-called missing mass of the Galaxy).« less

UCAC3 Proper Motion Survey. 2. Discovery of New Proper Motion Stars in UCAC3 with 0.40 yr-1 micro or = 0.18 yr-1 between Declinations -47 deg and 00 deg

DTIC Science & Technology

2012-02-01

Micron All Sky Survey ( 2MASS ) infrared photometry. We find five new red dwarf systems estimated to be within 25 pc. These discoveries support results...re-reduction of the pixel data (Zacharias 2010). In addition, data from the Two Micron All Sky Survey ( 2MASS ) were used in UCAC3 to probe for and...errors ranging from 50 to 200 mas when compared to 2MASS data. To identify previously known high proper motion (HPM) stars in the UCAC3, a source list was

HST Proper Motions of Distant Globular Clusters: Constraining the Formation & Mass of the Milky Way

NASA Astrophysics Data System (ADS)

Sohn, S. Tony; van der Marel, Roeland P.; Deason, Alis; Bellini, Andrea; Besla, Gurtina; Watkins, Laura

2018-04-01

Proper motions (PMs) are required to calculate accurate orbits of globular clusters (GCs) in the Milky Way (MW) halo. We present our HST program to create a PM database for 20 GCs at distances of R GC = 10-100 kpc. Targets are discussed along with PM measurement methods. We also describe how our PM results can be used for Gaia as an external check, and discuss the synergy between HST and Gaia as astrometric instruments in the coming years.

VizieR Online Data Catalog: Common proper motion stars in the Kepler field (Janes, 2017)

NASA Astrophysics Data System (ADS)

Janes, K. A.

2017-08-01

In a search of proper motion catalogs for common proper motion stars in the field of the Kepler spacecraft I identified 93 likely binary systems. A comparison of their rotation periods is a test of the gyrochronology concept. To find their periods I calculated the autocorrelation function (ACF) of the Kepler mission photometry for each star. In most systems for which good periods can be found, the cooler star has a longer period than the hotter component, in general agreement with models. However, there is a wide range in the gradients of lines connecting binary pairs in a period-color diagram. Furthermore, near the solar color, only a few stars have longer periods than the Sun, suggesting that they, and their cooler companions, are not much older than the Sun. In addition, there is an apparent gap at intermediate periods in the period distribution of the late K and early M stars. Either star formation in this direction has been variable, or stars evolve in period at a non-uniform rate, or some stars evolve more rapidly than others at the same mass. Finally, using the ACF as a measure of the activity level, I found that while the F, G, and early K stars become less active as their periods increase, there is no correlation between period and activity for the mid K to early M stars. (1 data file).

Measures and Relative Motions of Some Mostly F. G. W. Struve Doubles

NASA Astrophysics Data System (ADS)

Wiley, E. O.

2012-04-01

Measures of 59 pairs of double stars with long observational histories using "lucky imaging" techniques are reported. Relative motions of 59 pairs are investigated using histories of observation, scatter plots of relative motion, ordinary least-squares (OLS) and total proper motion analyses performed in "R," an open source programming language. A scatter plot of the coefficient of determinations derived from the OLS y|epoch and OLS x|epoch clearly separates common proper motion pairs from optical pairs and what are termed "long-period binary candidates." Differences in proper motion separate optical pairs from long-term binary candidates. An Appendix is provided that details how to use known rectilinear pairs as calibration pairs for the program REDUC.

A proper motion study of the globular cluster M55

NASA Astrophysics Data System (ADS)

Zloczewski, K.; Kaluzny, J.; Thompson, I. B.

2011-07-01

We have derived the absolute proper motion (PM) of the globular cluster M55 using a large set of CCD images collected with the du Pont telescope between 1997 and 2008. We find (μα cos δ, μδ) = (-3.31 ± 0.10, -9.14 ± 0.15) mas yr-1 relative to background galaxies. Membership status was determined for 16 945 stars with 14 < V < 21 from the central part of the cluster. The PM catalogue includes 52 variables, of which 43 are probable members of M55. This sample not only is dominated by pulsating blue straggler stars, but also includes five eclipsing binaries, three of which are main-sequence objects. The survey also identified several candidate blue, yellow and red straggler stars belonging to the cluster. We detected 15 likely members of the Sgr dSph galaxy located behind M55. The average PM for these stars was measured to be (μα cos δ, μδ) = (-2.23 ± 0.14, -1.83 ± 0.24) mas yr-1.

Knowing Our Neighbors: Four New Nearby High Proper Motion Systems

NASA Astrophysics Data System (ADS)

Bartlett, Jennifer L.; Lurie, John C.; Ianna, Philip A.; Riedel, Adric R.; Finch, Charlie T.; Winters, Jennifer G.; Jao, Wei-Chun; Subasavage, John P.; Henry, Todd J.

2017-01-01

Obtaining a well-understood, volume-limited (and ultimately volume-complete) sample of stellar systems within 25 pc is essential for determining the stellar luminosity function, the mass-luminosity relationship, the stellar velocity distribution, and the stellar multiplicity fraction. Such a sample also provides insight into the local star formation history. Towards that end, the Research Consortium On Nearby Stars (RECONS) team measures trigonometric parallaxes to establish which systems truly lie within the 25-pc radius of the Solar Neighborhood. Recent astrometric measurements with the CTIO/SMARTS 0.9-m telescope establish three high proper motion systems as members (2MASS J02511490-0352459, 2MASS J15345704-1418486, and 2MASS J09211410-2104446) and confirm a fourth (2MASS J23062928-0502285). All four proper motions exceed 0.9”/yr. 2MA0251 travels 2.1497±0.0009”/yr in 149.20±0.05° at a distance of 11.0±0.4 pc. 2M2306 moves 1.0344±0.0007”/yr in 118.50±0.08° at a distance of 12.7±0.2 pc. 2MA1534 goes 0.9726±0.0004”/yr in 251.50 ±0.05° at a distance of 10.93±0.10 pc. 2MA0921 shifts 0.9489±0.0003”/yr in 164.70±0.04° at a distance of 12.3±0.2 pc. The corresponding tangential velocities are 112.4, 62.4, 50.4, and 55.5 km/s whereas the median for parallaxes previously published by RECONS is 53 km/s. With radial velocities in the literature of -75.5 to 80.53 km/s, none of these is a candidate member of any young moving groups.To characterize these late M-early L systems more fully, RECONS obtained VRI photometry; their I -band magnitudes range from 14.10 to 16.55. Over their astrometric baselines of 7.75 to 8.99 years, these demonstrated long-term I-band variability of 0.0135 mag. or less, indicating they may be older systems.With each new confirmation, we come closer to completing the census of the Solar Neighborhood.NSF grants AST 05-07711 and AST 09-08402, NASA-SIM, Georgia State University, the University of Virginia, Hampden-Sydney College

X-Ray Analysis of the Proper Motion and Pulsar Wind Nebula for PSR J1741-2054

NASA Technical Reports Server (NTRS)

Auchettl, Katie; Slane, Patrick; Romani, Roger W.; Posselt, Bettina; Pavlov, George G.; Kargaltsev, Oleg; Ng, C-Y.; Temim, Tea; Weisskopf, Martin C.; Bykov, Andrei;

The imprint of proper motion of nonlinear structures on the cosmic microwave background

NASA Technical Reports Server (NTRS)

Tuluie, Robin; Laguna, Pablo

1995-01-01

We investigate the imprint of nonlinear matter condensations on the cosmic microwave background (CMB) in an Omega = 1, cold dark matter (CDM) model universe. Temperature anisotropies are obtained by numerically evolving matter inhomogeneities and CMB photons from the beginning of decoupling until the present epoch. The underlying density field produced by the inhomogeneities is followed from the linear, through the weakly clustered, into the fully nonlinear regime. We concentrate on CMB temperature distortions arising from variations in the gravitational potentials of nonlinear structures. We find two sources of temperature fluctuations produced by time-varying potentials: (1) anisotropies due to intrinsic changes in the gravitational potentials of the inhomogeneities and (2) anisotropies generated by the peculiar, bulk motion of the structures across the microwave sky. Both effects generate CMB anisotropies in the range of 10(exp -7) approximately less than or equal to (Delta T/T) approximately less than or equal to 10(exp -6) on scales of approximately 1 deg. For isolated structures, anisotropies due to proper motion exhibit a dipole-like signature in the CMB sky that in principle could yield information on the transverse velocity of the structures.

An X-ray Expansion and Proper Motion Study of the Magellanic Cloud Supernova Remnant J0509-6731 with the Chandra X-ray Observatory

NASA Astrophysics Data System (ADS)

Roper, Quentin; Filipovi, Miroslav; Allen, Glenn E.; Sano, Hidetoshi; Park, Laurence; Pannuti, Thomas G.; Sasaki, Manami; Haberl, Frank; Kavanagh, Patrick J.; Yamane, Yumiko; Yoshiike, Satoshi; Fujii, Kosuke; Fukui, Yasuo; Seitenzahl, Ivo R.

2018-05-01

Using archival Chandra data consisting of a total of 78.46 ksec over two epochs seven years apart, we have measured the expansion of the young (˜400 years old) type Ia Large Magellanic Cloud supernova remnant (SNR) J0509-6731. In addition, we use radial brightness profile matching to detect proper-motion expansion of this SNR, and estimate an speed of 7 500±1 700 km s-1. This is one of the only proper motion studies of extragalactic SNRs expansion that is able to derive an expansion velocity, and one of only two such studies of an extragalactic SNR to yield positive results in the X-rays. We find that this expansion velocity is consistent with an optical expansion study on this object. In addition, we examine the medium into which the SNR is expanding by examining the CO and neutral H I gas using radio data obtained from Mopra, the Australia Telescope Compact Array and Parkes radio telescopes. We also briefly compare this result with a recent radio survey, and find that our results predict a radio spectral index α of -0.67±0.07. This value is consistent with high frequency radio observations of MCSNR J0509-6731.

The Solar Neighborhood. XXV. Discovery of New Proper Motion Stars with 0.40 sec/yr > mu > or = 0.18 sec/yr Between Declinations -47 deg and 00 deg

NASA Technical Reports Server (NTRS)

Boyd, Mark R.; Winters, Jennifer G.; Henry, Todd J.; Jao, Wei-Chun; Finch, Charlie T.; Subasavage, John P.; Hambly, Nigel C.

2011-01-01

We present 2817 new southern proper motion systems with 0.40 sec/yr > mu > or = 0.18 sec/yr and declination between 47 deg and 00 deg. This is a continuation of the SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky. We use the same photometric relations as previous searches to provide distance estimates based on the assumption that the objects are single main-sequence stars. We find 79 new red dwarf systems predicted to be within 25 pc, including a few new components of previously known systems. Two systems--SCR 1731-2452 at 9.5 pc and SCR 1746-3214 at 9.9 pc--are anticipated to be within 10 pc. We also find 23 new white dwarf (WD) candidates with distance estimates of 15-66 pc, as well as 360 new red subdwarf candidates. With this search, we complete the SCR sweep of the southern sky for stars with mu > or = 0.18 sec/yr and R(sub 59F) < or = 16.5, resulting in a total of 5042 objects in 4724 previously unreported proper motion systems. Here we provide selected comprehensive lists from our SCR proper motion search to date, including 152 red dwarf systems estimated to be within 25 pc (9 within 10 pc), 46 WDs (10 within 25 pc), and 598 subdwarf candidates. The results of this search suggest that there are more nearby systems to be found at fainter magnitudes and lower proper motion limits than those probed so far.

Hubble Space Telescope Images of the HH 34 Jet and Bow Shock: Structure and Proper Motions

NASA Astrophysics Data System (ADS)

Reipurth, Bo; Heathcote, Steve; Morse, Jon; Hartigan, Pat; Bally, John

2002-01-01

We present new, deep Hα and [S II] images of the HH 34 jet and bow shock obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST), which reveal the structure of this fine HH flow with unprecedented detail. Many of the knots in the jet appear to form small working surfaces with bright [S II] cores and thin Hα filaments where the mini-bow shocks extend into the surrounding medium. In combination with earlier, short-exposure HST images we have determined very precise proper-motion vectors for the various shock structures in the outflow. The jet becomes visible within about an arcsecond of the source, where a new knot has emerged between our two epoch images; it has a space velocity of at least 300 km s-1, as derived from the proper motions and correcting for the 30° angle of the flow to the line of sight. The jet rapidly slows down to a mean space velocity of about 220 km s-1, with a standard deviation of 20 km s-1 among the jet knots. Such low internal velocities lead to weak shocks, consistent with the high [S II]/Hα ratio along the jet body and in accordance with the internal working surface model for jets. The jet motion appears to be ballistic, with no evidence for a turbulent boundary layer. The jet is well resolved and steadily expands with a half-opening angle of 0.4d. The large HH 34 working surface shows a multitude of knots, all of which are enveloped by a series of very thin, limb-brightened Hα-emitting filaments immediately behind the shock front where the flow faces into the preshock medium. One of these filaments developed four regularly spaced tiny knots between the two epochs, possibly due to a Rayleigh-Taylor instability along the filament or caused by the presence of small, dense clumps in the ambient medium. Proper motions of the HH 34 working surface show an obvious expansion due to material being squirted sideways. In addition to the large-scale S-shaped symmetry of the giant HH 34 flow, the jet shows a

Deformations and Rotational Ground Motions Inferred from Downhole Vertical Array Observations

NASA Astrophysics Data System (ADS)

Graizer, V.

2017-12-01

Only few direct reliable measurements of rotational component of strong earthquake ground motions are obtained so far. In the meantime, high quality data recorded at downhole vertical arrays during a number of earthquakes provide an opportunity to calculate deformations based on the differences in ground motions recorded simultaneously at different depths. More than twenty high resolution strong motion downhole vertical arrays were installed in California with primary goal to study site response of different geologic structures to strong motion. Deformation or simple shear strain with the rate γ is the combination of pure shear strain with the rate γ/2 and rotation with the rate of α=γ/2. Deformations and rotations were inferred from downhole array records of the Mw 6.0 Parkfield 2004, the Mw 7.2 Sierra El Mayor (Mexico) 2010, the Mw 6.5 Ferndale area in N. California 2010 and the two smaller earthquakes in California. Highest amplitude of rotation of 0.60E-03 rad was observed at the Eureka array corresponding to ground velocity of 35 cm/s, and highest rotation rate of 0.55E-02 rad/s associated with the S-wave was observed at a close epicentral distance of 4.3 km from the ML 4.2 event in Southern California at the La Cienega array. Large magnitude Sierra El Mayor earthquake produced long duration rotational motions of up to 1.5E-04 rad and 2.05E-03 rad/s associated with shear and surface waves at the El Centro array at closest fault distance of 33.4km. Rotational motions of such levels, especially tilting can have significant effect on structures. High dynamic range well synchronized and properly oriented instrumentation is necessary for reliable calculation of rotations from vertical array data. Data from the dense Treasure Island array near San Francisco demonstrate consistent change of shape of rotational motion with depth and material. In the frequency range of 1-15 Hz Fourier amplitude spectrum of vertical ground velocity is similar to the scaled tilt

HIGH-PRECISION RADIO AND INFRARED ASTROMETRY OF LSPM J1314+1320AB. I. PARALLAX, PROPER MOTIONS, AND LIMITS ON PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forbrich, Jan; Dupuy, Trent J.; Rizzuto, Aaron

2016-08-10

We present multi-epoch astrometric radio observations with the Very Long Baseline Array (VLBA) of the young ultracool-dwarf binary LSPM J1314+1320AB. The radio emission comes from the secondary star. Combining the VLBA data with Keck near-infrared adaptive-optics observations of both components, a full astrometric fit of parallax (π {sub abs} = 57.975 ± 0.045 mas, corresponding to a distance of d = 17.249 ± 0.013 pc), proper motion (μ {sub α} {sub cos} {sub δ} = −247.99 ± 0.10 mas yr{sup −1}, μ {sub δ} = −183.58 ± 0.22 mas yr{sup −1}), and orbital motion is obtained. Despite the fact thatmore » the two components have nearly identical masses to within ±2%, the secondary’s radio emission exceeds that of the primary by a factor of ≳30, suggesting a difference in stellar rotation history, which could result in different magnetic field configurations. Alternatively, the emission could be anisotropic and beamed toward us for the secondary but not for the primary. Using only reflex motion, we exclude planets of mass 0.7–10 M {sub jup} with orbital periods of 600–10 days, respectively. Additionally, we use the full orbital solution of the binary to derive an upper limit for the semimajor axis of 0.23 au for stable planetary orbits within this system. These limits cover a parameter space that is inaccessible with, and complementary to, near-infrared radial velocity surveys of ultracool dwarfs. Our absolute astrometry will constitute an important test for the astrometric calibration of Gaia .« less

A Deep Proper Motion Catalog Within the Sloan Digital Sky Survey Footprint. II. The White Dwarf Luminosity Function

NASA Astrophysics Data System (ADS)

Munn, Jeffrey A.; Harris, Hugh C.; von Hippel, Ted; Kilic, Mukremin; Liebert, James W.; Williams, Kurtis A.; DeGennaro, Steven; Jeffery, Elizabeth; Dame, Kyra; Gianninas, A.; Brown, Warren R.

2017-01-01

A catalog of 8472 white dwarf (WD) candidates is presented, selected using reduced proper motions from the deep proper motion catalog of Munn et al. Candidates are selected in the magnitude range 16< r< 21.5 over 980 square degrees, and 16< r< 21.3 over an additional 1276 square degrees, within the Sloan Digital Sky Survey (SDSS) imaging footprint. Distances, bolometric luminosities, and atmospheric compositions are derived by fitting SDSS ugriz photometry to pure hydrogen and helium model atmospheres (assuming surface gravities {log} {\\text{}}g=8). The disk white dwarf luminosity function (WDLF) is constructed using a sample of 2839 stars with 5.5< {M}{bol}< 17, with statistically significant numbers of stars cooler than the turnover in the luminosity function. The WDLF for the halo is also constructed, using a sample of 135 halo WDs with 5< {M}{bol}< 16. We find space densities of disk and halo WDs in the solar neighborhood of 5.5+/- 0.1× {10}-3 {{pc}}-3 and 3.5+/- 0.7× {10}-5 {{pc}}-3, respectively. We resolve the bump in the disk WDLF due to the onset of fully convective envelopes in WDs, and see indications of it in the halo WDLF as well.

Photometry and Proper Motions of M, L, and T Dwarfs from the Pan-STARRS1 3π Survey

NASA Astrophysics Data System (ADS)

Best, William M. J.; Magnier, Eugene A.; Liu, Michael C.; Aller, Kimberly M.; Zhang, Zhoujian; Burgett, W. S.; Chambers, K. C.; Draper, P.; Flewelling, H.; Kaiser, N.; Kudritzki, R.-P.; Metcalfe, N.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

2018-01-01

We present a catalog of 9888 M, L and T dwarfs detected in the Pan-STARRS1 3π Survey (PS1), covering three-quarters of the sky. Our catalog contains nearly all known objects of spectral types L0–T2 in the PS1 field, with objects as early as M0 and as late as T9, and includes PS1, 2MASS, AllWISE, and Gaia DR1 photometry. We analyze the different types of photometry reported by PS1 and use two types in our catalog in order to maximize both depth and accuracy. Using parallaxes from the literature, we construct empirical SEDs for field ultracool dwarfs spanning 0.5–12 μm. We determine typical colors of M0–T9 dwarfs and highlight the distinctive colors of subdwarfs and young objects. We combine astrometry from PS1, 2MASS, and Gaia DR1 to calculate new proper motions for our catalog. We achieve a median precision of 2.9 mas yr‑1, a factor of ≈3‑10 improvement over previous large catalogs. Our catalog contains proper motions for 2405 M6–T9 dwarfs and includes the largest set of homogeneous proper motions for L and T dwarfs published to date, 406 objects for which there were no previous measurements, and 1176 objects for which we improve upon previous literature values. We analyze the kinematics of ultracool dwarfs in our catalog and find evidence that bluer but otherwise generic late-M and L field dwarfs (i.e., not subdwarfs) tend to have tangential velocities higher than those of typical field objects. With the public release of the PS1 data, this survey will continue to be an essential tool for characterizing the ultracool dwarf population.

Renewal of K-NET (National Strong-motion Observation Network of Japan)

NASA Astrophysics Data System (ADS)

Kunugi, T.; Fujiwara, H.; Aoi, S.; Adachi, S.

2004-12-01

The National Research Institute for Earth Science and Disaster Prevention (NIED) operates K-NET (Kyoshin Network), the national strong-motion observation network, which evenly covers the whole of Japan at intervals of 25 km on average. K-NET was constructed after the Hyogoken-Nambu (Kobe) earthquake in January 1995, and began operation in June 1996. Thus, eight years have passed since K-NET started, and large amounts of strong-motion records have been obtained. As technology has progressed and new technologies have become available, NIED has developed a new K-NET with improved functionality. New seismographs have been installed at 443 observatories mainly in southwestern Japan where there is a risk of strong-motion due to the Nankai and Tonankai earthquakes. The new system went into operation in June 2004, although seismographs have still to be replaced in other areas. The new seismograph (K-NET02) consists of a sensor module, a measurement module and a communication module. A UPS, a GPS antenna and a dial-up router are also installed together with a K-NET02. A triaxial accelerometer, FBA-ES-DECK (Kinemetrics Inc.) is built into the sensor module. The measurement module functions as a conventional strong-motion seismograph for high-precision observation. The communication module can perform sophisticated processes, such as calculation of the Japan Meteorological Agency (JMA) seismic intensity, continuous recording of data and near real-time data transmission. It connects to the Data Management Center (DMC) using an ISDN line. In case of a power failure, the measurement module can control the power supply to the router and the communication module to conserve battery power. One of the main features of K-NET02 is a function for processing JMA seismic intensity. K-NET02 functions as a proper seismic intensity meter that complies with the official requirements of JMA, although the old strong-motion seismograph (K-NET95) does not calculate seismic intensity. Another

Reconstructing the outburst history of Eta Carinae from WFPC2 proper motions

NASA Astrophysics Data System (ADS)

Smith, Nathan

2011-10-01

The HST archive contains several epochs of WFPC2 images of the nebula around Eta Carinae taken over a 15-year timespan, although only the earliest few years of data have been analyzed and published. The fact that all these images were taken with the same instrument, with the same pixel sampling and field distortion, makes them an invaluable resource for accurately measuring the expanding ejecta. So far, analysis of a subset of the data {with only a few year baseline} has shown that Eta Car's nebula was ejected around the time of the Great Eruption in the 1840s, but the full 15-yr dataset has much greater untapped potential. Historical data show multiple peaks in the light curve during the 1840s eruption, possibly the result of violent stellar collisions in the eccentric binary system. Proper motions with the full 15-yr dataset will definitively show if one of these is associated with the main mass ejection. Older material outside the main bipolar nebula traces previous major outbursts of the star with no recorded historical observations. We propose an ambitious reduction and analysis of the complete WFPC2 imaging dataset of Eta Car. These data can reconstruct its violent mass-loss history over the past several thousand years. This will constrain the behavior and timescale of eruptive mass loss in pre-SN evolution. The existence of several epochs over a long timespan will date older parts of the nebula that have not yet been measured, and can even measure the deceleration of the ejecta for the first time, essential for understanding their shaping and shock excitation during the nebula's continuing hydrodynamic evolution.

THE SOLAR NEIGHBORHOOD. XXV. DISCOVERY OF NEW PROPER MOTION STARS WITH 0.''40 yr{sup -1} > {mu} {>=} 0.''18 yr{sup -1} BETWEEN DECLINATIONS -47{sup 0} AND 00{sup 0}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyd, Mark R.; Winters, Jennifer G.; Henry, Todd J.

2011-07-15

We present 2817 new southern proper motion systems with 0.''40 yr{sup -1} > {mu} {>=} 0.''18 yr{sup -1} and declination between -47{sup 0} and 00{sup 0}. This is a continuation of the SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky. We use the same photometric relations as previous searches to provide distance estimates based on the assumption that the objects are single main-sequence stars. We find 79 new red dwarf systems predicted to be within 25 pc, including a few new components of previously known systems. Two systems-SCR 1731-2452 at 9.5 pc and SCR 1746-3214 at 9.9 pc-are anticipatedmore » to be within 10 pc. We also find 23 new white dwarf (WD) candidates with distance estimates of 15-66 pc, as well as 360 new red subdwarf candidates. With this search, we complete the SCR sweep of the southern sky for stars with {mu} {>=} 0.''18 yr{sup -1} and R{sub 59F} {<=} 16.5, resulting in a total of 5042 objects in 4724 previously unreported proper motion systems. Here we provide selected comprehensive lists from our SCR proper motion search to date, including 152 red dwarf systems estimated to be within 25 pc (9 within 10 pc), 46 WDs (10 within 25 pc), and 598 subdwarf candidates. The results of this search suggest that there are more nearby systems to be found at fainter magnitudes and lower proper motion limits than those probed so far.« less

Get Ready for Gaia: Cool White Dwarfs in Common Proper Motion with Tycho Stars

NASA Astrophysics Data System (ADS)

Hambly, N.; Rowell, N.; Lam, M.

2017-03-01

We discuss the Gaia Data Release 1 (September 2016) and preliminary work on maximising the benefit for cool white dwarf (WD) science in advance of the full parallax catalogue which will appear around one year later in DR2. The Tycho catalogue is used in conjunction with the all-sky ground based astrometric/ photometric SuperCOSMOS Sky Survey in order to identify candidate faint common proper motion objects to the Tycho stars. Gaia DR1 is supplemented by the Tycho-Gaia Astrometric Solution catalogue containing some 2 million parallaxes with Hipparcos-like precision for Tycho stars. While hotter, brighter WDs are present in Tycho, cooler examples are much rarer (if present at all) and CPM offers one method to infer precision distances for a statistically useful sample of these very faint WDs.

Visual Target Tracking in the Presence of Unknown Observer Motion

NASA Technical Reports Server (NTRS)

Williams, Stephen; Lu, Thomas

2009-01-01

Much attention has been given to the visual tracking problem due to its obvious uses in military surveillance. However, visual tracking is complicated by the presence of motion of the observer in addition to the target motion, especially when the image changes caused by the observer motion are large compared to those caused by the target motion. Techniques for estimating the motion of the observer based on image registration techniques and Kalman filtering are presented and simulated. With the effects of the observer motion removed, an additional phase is implemented to track individual targets. This tracking method is demonstrated on an image stream from a buoy-mounted or periscope-mounted camera, where large inter-frame displacements are present due to the wave action on the camera. This system has been shown to be effective at tracking and predicting the global position of a planar vehicle (boat) being observed from a single, out-of-plane camera. Finally, the tracking system has been extended to a multi-target scenario.

Early Improper Motion Detection in Golf Swings Using Wearable Motion Sensors: The First Approach

PubMed Central

Stančin, Sara; Tomažič, Sašo

2013-01-01

This paper presents an analysis of a golf swing to detect improper motion in the early phase of the swing. Led by the desire to achieve a consistent shot outcome, a particular golfer would (in multiple trials) prefer to perform completely identical golf swings. In reality, some deviations from the desired motion are always present due to the comprehensive nature of the swing motion. Swing motion deviations that are not detrimental to performance are acceptable. This analysis is conducted using a golfer's leading arm kinematic data, which are obtained from a golfer wearing a motion sensor that is comprised of gyroscopes and accelerometers. Applying the principal component analysis (PCA) to the reference observations of properly performed swings, the PCA components of acceptable swing motion deviations are established. Using these components, the motion deviations in the observations of other swings are examined. Any unacceptable deviations that are detected indicate an improper swing motion. Arbitrarily long observations of an individual player's swing sequences can be included in the analysis. The results obtained for the considered example show an improper swing motion in early phase of the swing, i.e., the first part of the backswing. An early detection method for improper swing motions that is conducted on an individual basis provides assistance for performance improvement. PMID:23752563

Early improper motion detection in golf swings using wearable motion sensors: the first approach.

PubMed

Stančin, Sara; Tomažič, Sašo

2013-06-10

This paper presents an analysis of a golf swing to detect improper motion in the early phase of the swing. Led by the desire to achieve a consistent shot outcome, a particular golfer would (in multiple trials) prefer to perform completely identical golf swings. In reality, some deviations from the desired motion are always present due to the comprehensive nature of the swing motion. Swing motion deviations that are not detrimental to performance are acceptable. This analysis is conducted using a golfer's leading arm kinematic data, which are obtained from a golfer wearing a motion sensor that is comprised of gyroscopes and accelerometers. Applying the principal component analysis (PCA) to the reference observations of properly performed swings, the PCA components of acceptable swing motion deviations are established. Using these components, the motion deviations in the observations of other swings are examined. Any unacceptable deviations that are detected indicate an improper swing motion. Arbitrarily long observations of an individual player's swing sequences can be included in the analysis. The results obtained for the considered example show an improper swing motion in early phase of the swing, i.e., the first part of the backswing. An early detection method for improper swing motions that is conducted on an individual basis provides assistance for performance improvement.

Characterization of the Praesepe Star Cluster by Photometry and Proper Motions With 2MASS, PPMXL, and Pan-STARRS

DTIC Science & Technology

2014-03-20

reserved. Printed in the U.S.A. CHARACTERIZATION OF THE PRAESEPE STAR CLUSTER BY PHOTOMETRY AND PROPER MOTIONS WITH 2MASS , PPMXL, AND Pan-STARRS P. F. Wang1... 2MASS ) and the Sloan Digital Sky Survey (SDSS) data, covering a sky area of 100 deg2, Adams et al. (2002) extended the lower main sequence to 0.1M, and...incompleteness is caused by the detection limits of USNO-B1 and 2MASS . Recently, Khalaj & Baumgardt (2013) used SDSS and PPMXL data to characterize

Measurement of the Expansion Proper Motions of the Ou4 Giant Bipolar Outflow to Determine its Distance and its True Nature

NASA Astrophysics Data System (ADS)

Grosso, Nicolas

2016-10-01

Ou4 is a giant bipolar outflow with a total length of 1.2 degrees on the sky that was discovered in the optical in the direction of the blister HII region Sh2-129. The distance, the nature, and the driving source of Ou4 are, however, not known. Ou4 is relevant for the study of the eruptive phenomena producing collimated outflows from evolved low-mass binary stars and young, massive stellar systems. Our morpho-kinematics study of the Ou4 south bow-shock has allowed us to predict its expansion proper motion that is directly related to its distance. We propose to image the brightest [O III] emission of this bow-shock with the UVIS channel of the WFC3 in Cycle 24 and 26 in order to determine the distance of this largest known stellar bipolar outflow from its expansion proper motions. This measurement is crucial to determine the true nature of Ou4: either a foreground planetary nebula or a giant bipolar outflow launched 90,000 years ago by HR 8119, the young massive triple system ionising Sh2-129.

Tycho- Gaia Astrometric Solution Parallaxes and Proper Motions for Five Galactic Globular Clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watkins, Laura L.; Van der Marel, Roeland P., E-mail: lwatkins@stsci.edu

2017-04-20

We present a pilot study of Galactic globular cluster (GC) proper motion (PM) determinations using Gaia data. We search for GC stars in the Tycho- Gaia Astrometric Solution (TGAS) catalog from Gaia Data Release 1 (DR1), and identify five members of NGC 104 (47 Tucanae), one member of NGC 5272 (M3), five members of NGC 6121 (M4), seven members of NGC 6397, and two members of NGC 6656 (M22). By taking a weighted average of member stars, fully accounting for the correlations between parameters, we estimate the parallax (and, hence, distance) and PM of the GCs. This provides a homogeneousmore » PM study of multiple GCs based on an astrometric catalog with small and well-controlled systematic errors and yields random PM errors similar to existing measurements. Detailed comparison to the available Hubble Space Telescope ( HST ) measurements generally shows excellent agreement, validating the astrometric quality of both TGAS and HST . By contrast, comparison to ground-based measurements shows that some of those must have systematic errors exceeding the random errors. Our parallax estimates have uncertainties an order of magnitude larger than previous studies, but nevertheless imply distances consistent with previous estimates. By combining our PM measurements with literature positions, distances, and radial velocities, we measure Galactocentric space motions for the clusters and find that these also agree well with previous analyses. Our analysis provides a framework for determining more accurate distances and PMs of Galactic GCs using future Gaia data releases. This will provide crucial constraints on the near end of the cosmic distance ladder and provide accurate GC orbital histories.« less

Real-time observation of valence electron motion.

PubMed

Goulielmakis, Eleftherios; Loh, Zhi-Heng; Wirth, Adrian; Santra, Robin; Rohringer, Nina; Yakovlev, Vladislav S; Zherebtsov, Sergey; Pfeifer, Thomas; Azzeer, Abdallah M; Kling, Matthias F; Leone, Stephen R; Krausz, Ferenc

2010-08-05

The superposition of quantum states drives motion on the atomic and subatomic scales, with the energy spacing of the states dictating the speed of the motion. In the case of electrons residing in the outer (valence) shells of atoms and molecules which are separated by electronvolt energies, this means that valence electron motion occurs on a subfemtosecond to few-femtosecond timescale (1 fs = 10(-15) s). In the absence of complete measurements, the motion can be characterized in terms of a complex quantity, the density matrix. Here we report an attosecond pump-probe measurement of the density matrix of valence electrons in atomic krypton ions. We generate the ions with a controlled few-cycle laser field and then probe them through the spectrally resolved absorption of an attosecond extreme-ultraviolet pulse, which allows us to observe in real time the subfemtosecond motion of valence electrons over a multifemtosecond time span. We are able to completely characterize the quantum mechanical electron motion and determine its degree of coherence in the specimen of the ensemble. Although the present study uses a simple, prototypical open system, attosecond transient absorption spectroscopy should be applicable to molecules and solid-state materials to reveal the elementary electron motions that control physical, chemical and biological properties and processes.

Three very cool degenerate stars in Luyten common proper motion binaries - Implications for the age of the galactic disk

NASA Technical Reports Server (NTRS)

Hintzen, Paul; Oswalt, Terry D.; Liebert, James; Sion, Edward M.

1989-01-01

During the course of a spectroscopic study of Luyten common proper motion (CPM) stars, spectrophotometric observations have been obtained of three binaries containing degenerate stars with estimated absolute magnitudes M(V) of about 16. Each of the three pairs consists of a yellow degenerate star primary and a DC 13 + secondary 1.4-2.3 mag fainter. One of the primary stars is spectral class DC 7, another is a sharp-lined DA 8, and the third shows peculiar broad absorption features which we interpret as pressure-shifted C2 Swan bands. The LP 701 - 69/70 system has survived for over 8 billion years without disruption by passing stars, despite its 1500 a.u. orbital major axis. The three cool degenerate companions nearly double the available sample of stars at the low-luminosity terminus of the white dwarf cooling sequence. These findings appear consistent with the conclusion that degenerate stars in the old disk population have not had time to evolve to a luminosity fainter than M(V) about 16.2.

Mass of the Local Group from Proper Motions of Distant Dwarf Galaxies

NASA Astrophysics Data System (ADS)

van der Marel, Roeland

2010-09-01

The Local Group and its two dominant spirals, the Milky Way and M31, have become the benchmark for testing many aspects of cosmological and galaxy formation theories, due to many exciting new discoveries in the past decade. However, it is difficult to put results in a proper cosmological context, because our knowledge of the mass M of the Local Group remains uncertain by a factor 4. In units of 10^{12} solar masses, a spherical infall model for the zero-velocity surface gives M 1.3; the sum of estimates for the Milky Way and M31 masses gives M 2.6; and the Local Group Timing argument for the M31 orbit gives M 5.6. It is possible to discriminate between the proposed masses by calculating the orbits of galaxies at the edge of the Local Group, which requires knowledge of transverse velocity components. We therefore propose to use ACS/WFC to determine the proper motions of the 4 dwarf galaxies near the edge of the Local Group {Cetus, Leo A, Tucana, Sag DIG} for which deep first epoch data {with 5-7 year time baselines} already exist in the HST Archive. Our team has extensive expertise with HST astrometric science, and our past/ongoing work for, e.g., Omega Cen, LMC/SMC and M31 show that the necessary astrometric accuracy is within the reach of HST's demonstrated capabilities. We have developed, tested, and published a new technique that uses compact background galaxies as astrometric reference sources, and we have already reduced the first epoch data. The final predicted transverse velocity accuracy, 36 km/s when averaged over the sample, will be sufficient to discriminate between each of the proposed Local Group masses at 2-sigma significance {4-sigma between the most extreme values}. Our project will yield the most accurate Local Group mass determination to date, and only HST can achieve the required accuracy.

Beyond the Blur: Construction and Characterization of the First Autonomous AO System, and, An AO Survey of Magnetar Proper Motions

NASA Astrophysics Data System (ADS)

Tendulkar, Shriharsh Prakash

Adaptive optics (AO) corrects distortions created by atmospheric turbulence and delivers diffraction-limited images on ground-based telescopes. The vastly improved spatial resolution and sensitivity has been utilized for studying everything from the magnetic fields of sunspots upto the internal dynamics of high-redshift galaxies. This thesis about AO science from small and large telescopes is divided into two parts: Robo-AO and magnetar kinematics. In the first part, I discuss the construction and performance of the world's first fully autonomous visible light AO system, Robo-AO, at the Palomar 60-inch telescope. Robo-AO operates extremely efficiently with an overhead < 50s, typically observing about 22 targets every hour. We have performed large AO programs observing a total of over 7,500 targets since May 2012. In the visible band, the images have a Strehl ratio of about 10% and achieve a contrast of upto 6 magnitudes at a separation of 1‧‧. The full-width at half maximum achieved is 110-130 milli-arcsecond. I describe how Robo-AO is used to constrain the evolutionary models of low-mass pre-main-sequence stars by measuring resolved spectral energy distributions of stellar multiples in the visible band, more than doubling the current sample. I conclude this part with a discussion of possible future improvements to the Robo-AO system. In the second part, I describe a study of magnetar kinematics using high-resolution near-infrared (NIR) AO imaging from the 10-meter Keck II telescope. Measuring the proper motions of five magnetars with a precision of upto 0.7 milli-arcsecond/yr -1, we have more than tripled the previously known sample of magnetar proper motions and proved that magnetar kinematics are equivalent to those of radio pulsars. We conclusively showed that SGR 1900+14 and SGR 1806-20 were ejected from the stellar clusters with which they were traditionally associated. The inferred kinematic ages of these two magnetars are 6 +/- 1.8 kyr and 650 +/-3 00

Dynamical Constraints on the Dark Matter Distribution of the Sculptor Dwarf Spheroidal from Stellar Proper Motions

NASA Astrophysics Data System (ADS)

Strigari, Louis E.; Frenk, Carlos S.; White, Simon D. M.

2018-06-01

We compare the transverse velocity dispersions recently measured within the Sculptor dwarf spheroidal galaxy to the predictions of our previously published dynamical model. This was designed to fit the observed number count and velocity dispersion profiles of both metal-rich and metal-poor stars, both in cored and in cusped potentials. At the projected radius where the proper motions (PMs) were measured, this model (with no change in parameters) predicts transverse dispersions in the range of 6–9.5 km s‑1, with the tangential dispersion about 1 km s‑1 larger than the (projected) radial dispersion. Both dispersions are predicted to be about 1 km s‑1 larger for metal-poor than for metal-rich stars. At this projected radius, cored and cusped potentials predict almost identical transverse dispersions. The measured tangential dispersion (8.5 ± 3.2 km s‑1) agrees remarkably well with these predictions, while the measured radial dispersion (11.5 ± 4.3 km s‑1) differs only at about the 1σ level. Thus, the PM data are in excellent agreement with previous data, but do not help to distinguish between cored and cusped potentials. This will require velocity dispersion data (either from PMs or from radial velocities) with uncertainties well below 1 km s‑1 over a range of projected radii.

Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. 3; Measurement for URSA Minor

NASA Technical Reports Server (NTRS)

Piatek, Slawomir; Pryor, Carlton; Bristow, Paul; Olszewski, Edward W.; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

2005-01-01

This article presents a measurement of the proper motion of the Ursa Minor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope in two distinct fields. Each field contains a quasi-stellar object that serves as the "reference point". Integrating the motion of Ursa Minor in a realistic potential for the Milky Way produces orbital elements. The perigalacticon and apogalacticon are 40 (10, 76) and 89 (78, 160) kpc, respectively, where the values in the parentheses represent the 95% confidence intervals derived from Monte Carlo experiments. The eccentricity of the orbit is 0.39 (0.09, 0.79), and the orbital period is 1.5 (1.1, 2.7) Gyr. The orbit is retrograde and inclined by 124 degrees (94 deg, 36 deg ) to the Galactic plane. Ursa Minor is not a likely member of a proposed stream of galaxies on similar orbits around the Milky Way, nor is the plane of its orbit coincident with a recently proposed planar alignment of galaxies around the Milky Way. Comparing the orbits of Ursa Minor and Carina shows no reason for the different star formation histories of these two galaxies. Ursa Minor must contain dark matter to have a high probability of having survived disruption by the Galactic tidal force until the present.

DIFFERENTIAL PROPER-MOTION MEASUREMENTS OF THE CYGNUS EGG NEBULA: THE PRESENCE OF EQUATORIAL OUTFLOWS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ueta, Toshiya; Tomasino, Rachael L.; Ferguson, Brian A.

2013-08-01

We present the results of differential proper-motion analyses of the Egg Nebula (RAFGL 2688, V1610 Cyg) based on the archived two-epoch optical data taken with the Hubble Space Telescope. First, we determined that the polarization characteristics of the Egg Nebula are influenced by the higher optical depth of the central regions of the nebula (i.e., the 'dustsphere' of {approx}10{sup 3} AU radius), causing the nebula to illuminate in two steps-the direct starlight is first channeled into bipolar cavities and then scattered off to the rest of the nebula. We then measured the amount of motion of local structures and themore » signature concentric arcs by determining their relative shifts over the 7.25 yr interval. Based on our analysis, which does not rely on the single-scattering assumption, we concluded that the lobes have been excavated by a linear expansion along the bipolar axis for the past {approx}400 yr, while the concentric arcs have been generated continuously and moving out radially at about 10 km s{sup -1} for the past {approx}5500 yr, and there appears to be a colatitudinally increasing trend in the radial expansion velocity field of the concentric arcs. Numerical investigations into the mass-loss modulation by the central binary system exist, which predict such a colatitudinally increasing expansion velocity field in the spiral-shock trails of the mass-loss ejecta. Therefore, the Egg Nebula may represent a rare edge-on case of the binary-modulated circumstellar environs, corroborating the previous theoretical predictions.« less

THE PROPER MOTION AND X-RAY ANALYSIS OF THE PULSAR WIND NEBULA, PSR J1741-2054 USING CHANDRA.

NASA Astrophysics Data System (ADS)

Auchettl, Katie; Slane, Patrick O.; Romani, Roger W.; Kargaltsev, Oleg; Pavlov, George G.

2014-08-01

A pulsar dissipates its rotational energy by generating relativistic winds, which in turn produces a population of high energy electrons and positions that we observe as a synchrotron emitting nebula. If the pulsar has a high space velocity, the corresponding nebula will have a bow-shock morphology due to the pulsar wind being confined by ram pressure. Pulsar wind nebulae (PWNe) provide a good test bed to study the dynamics and interaction of relativistic outflows with their environment and the corresponding shocks that result from these interactions. They can also aid in understanding the evolution of the neutron star and the properties of the local medium with which they are interacting. Here we report on the X-ray analysis of PSR J1741-2054 carried out as a part of the Chandra XVP program (6 ACIS-S observations, totalling ~300 ks over 5 months). By registering this new epoch of observations using X-ray point sources in the field of view to an archival observation taken 3.2 years earlier, we are able to measure the proper motion of the pulsar with >3σ significance. We also investigate the spatial and spectral properties of the pulsar, its compact nebula and extended tail. We find that the compact nebula can be well described with an absorbed power-law with photon index of Γ=1.6+/-0.2, while the tail shows no evidence of variation in the spectral index with the distance from the pulsar. We have also investigated the X-ray spectrum of the neutron star. We find nonthermal emission accompanied by a significant thermal component and will provide constraints on the overall nature of the emission.

Outward Motions of SiO Masers around VX Sgr

NASA Astrophysics Data System (ADS)

Su, J. B.; Shen, Z.-Q.; Chen, X.; Jiang, D. R.

2014-09-01

We report the proper motions of SiO maser features around VX Sgr from the two-epoch VLBA observations (2006 December 15 and 2007 August 19). The majority of maser feature activities show a trend of outward motions. It is consistent with our previous finding that the outflow may play an important role for SiO maser pumping.

Abundance Ratios in a Common Proper Motion Pair: Chemical Evidence of Accreted Substructure in the Halo Field?

NASA Astrophysics Data System (ADS)

King, Jeremy R.

1997-06-01

Elemental abundances are presented for the metal-poor ([Fe/H] =-1.50) common proper motion pair HD 134439 and HD 134440. The abundances for the two stars are in very good agreement, with the neutral species showing only a small difference (˜0.05 dex) which is well within the statistical and Teff uncertainties. The essentially identical abundances, kinematics, and parallaxes of the two stars indicate that they share a common history. This history, however, appears to be different than other metal-poor stars. Suggestions, based on kinematic evidence, that these two-stars are representative of a distinct accretion event are corroborated by our abundance ratios, which indicate [Mg/Fe], [Si/Fe], and [Ca/Fe] are consistently some ˜0.3 dex lower than the vast majority of metal-poor field stars. Such underabundances have been predicted in environments like dwarf Spheroidals and the Magellanic Clouds. Moreover, our abundance ratio deficiencies are consistent with those recently observed in the the anomalously young globular clusters Rup 106 and Pal 12, which have been alleged to have been accreted from the Magellanic Clouds. The [Fe/H] and retrograde motion of the common proper motion pair are characteristic of the subset of Galactic globular clusters suggested by Rodgers & Paltoglou [ApJ, 283, L5 (1984)] to have been coalesced from satellite galaxies. We also call attention to the metal-poor subgiant BD+03 740 as another possible representative of an accreted or chaotically formed member of the halo field. If recent Fe analyses of this star are correct, then [Mg/Fe] and [0/Fe] are 0.5 dex lower than in other metal-poor field stars. This star also has a relatively low photometrically inferred age; relative youth has been noted as a possible characteristic of accreted field populations, and is qualitatively consistent with the young ages of the purportedly accreted globular clusters Rup 106, Pal 12, Ter 7, and Arp 2. Additionally, the revised [O/Fe] ratio for BD+03 740

Helmet Fit and Cervical Spine Motion in Collegiate Men's Lacrosse Athletes Secured to a Spine Board

PubMed Central

Petschauer, Meredith A.; Schmitz, Randy; Gill, Diane L.

2010-01-01

Abstract Context: Proper management of cervical spine injuries in men's lacrosse players depends in part upon the ability of the helmet to immobilize the head. Objective: To determine if properly and improperly fitted lacrosse helmets provide adequate stabilization of the head in the spine-boarded athlete. Design: Crossover study. Setting: Sports medicine research laboratory. Patients or Other Participants: Eighteen healthy collegiate men's lacrosse players. Intervention(s): Participants were asked to move their heads through 3 planes of motion after being secured to a spine board under 3 helmet conditions. Main Outcome Measure(s): Change in range of motion in the cervical spine was calculated for the sagittal, frontal, and transverse planes for both head-to-thorax and helmet-to-thorax range of motion in all 3 helmet conditions (properly fitted, improperly fitted, and no helmet). Results: Head-to-thorax range of motion with the properly fitted and improperly fitted helmets was greater than in the no-helmet condition (P < .0001). In the sagittal plane, range of motion was greater with the improperly fitted helmet than with the properly fitted helmet. No difference was observed in helmet-to-thorax range of motion between properly and improperly fitted helmet conditions. Head-to-thorax range of motion was greater than helmet-to-thorax range of motion in all 3 planes (P < .0001). Conclusions: Cervical spine motion was minimized the most in the no-helmet condition, indicating that in lacrosse players, unlike football players, the helmet may need to be removed before stabilization. PMID:20446833

Can earthquake source inversion benefit from rotational ground motion observations?

NASA Astrophysics Data System (ADS)

Igel, H.; Donner, S.; Reinwald, M.; Bernauer, M.; Wassermann, J. M.; Fichtner, A.

2015-12-01

With the prospects of instruments to observe rotational ground motions in a wide frequency and amplitude range in the near future we engage in the question how this type of ground motion observation can be used to solve seismic inverse problems. Here, we focus on the question, whether point or finite source inversions can benefit from additional observations of rotational motions. In an attempt to be fair we compare observations from a surface seismic network with N 3-component translational sensors (classic seismometers) with those obtained with N/2 6-component sensors (with additional colocated 3-component rotational motions). Thus we keep the overall number of traces constant. Synthetic seismograms are calculated for known point- or finite-source properties. The corresponding inverse problem is posed in a probabilistic way using the Shannon information content as a measure how the observations constrain the seismic source properties. The results show that with the 6-C subnetworks the source properties are not only equally well recovered (even that would be benefitial because of the substantially reduced logistics installing N/2 sensors) but statistically significant some source properties are almost always better resolved. We assume that this can be attributed to the fact the (in particular vertical) gradient information is contained in the additional rotational motion components. We compare these effects for strike-slip and normal-faulting type sources. Thus the answer to the question raised is a definite "yes". The challenge now is to demonstrate these effects on real data.

The Solar Neighborhood. XXVII. Discovery of New Proper Motion Stars with μ >= 0farcs18 yr-1 in the Southern Sky with 16.5 < R 59F <= 18.0

NASA Astrophysics Data System (ADS)

Boyd, Mark R.; Henry, Todd J.; Jao, Wei-Chun; Subasavage, John P.; Hambly, Nigel C.

2011-09-01

Here we present 1584 new southern proper motion systems with μ >= 0farcs18 yr-1 and 16.5 > R 59F >= 18.0. This search complements the six previous SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky for stars within the same proper motion range, but with R 59F <= 16.5. As in previous papers, we present distance estimates for these systems and find that three systems are estimated to be within 25 pc, including one, SCR 1546-5534, possibly within the RECONS 10 pc horizon at 6.7 pc, making it the second nearest discovery of the searches. We find 97 white dwarf candidates with distance estimates between 10 and 120 pc, as well as 557 cool subdwarf candidates. The subdwarfs found in this paper make up nearly half of the subdwarf systems reported from our SCR searches and are significantly redder than those discovered thus far. The SCR searches have now found 155 red dwarfs estimated to be within 25 pc, including 10 within 10 pc. In addition, 143 white dwarf candidates and 1155 cool subdwarf candidates have been discovered. The 1584 systems reported here augment the sample of 4724 systems previously discovered in our SCR searches and imply that additional systems fainter than R 59F = 18.0 are yet to be discovered.

Spatial and spectral interpolation of ground-motion intensity measure observations

USGS Publications Warehouse

Worden, Charles; Thompson, Eric M.; Baker, Jack W.; Bradley, Brendon A.; Luco, Nicolas; Wilson, David

2018-01-01

Following a significant earthquake, ground‐motion observations are available for a limited set of locations and intensity measures (IMs). Typically, however, it is desirable to know the ground motions for additional IMs and at locations where observations are unavailable. Various interpolation methods are available, but because IMs or their logarithms are normally distributed, spatially correlated, and correlated with each other at a given location, it is possible to apply the conditional multivariate normal (MVN) distribution to the problem of estimating unobserved IMs. In this article, we review the MVN and its application to general estimation problems, and then apply the MVN to the specific problem of ground‐motion IM interpolation. In particular, we present (1) a formulation of the MVN for the simultaneous interpolation of IMs across space and IM type (most commonly, spectral response at different oscillator periods) and (2) the inclusion of uncertain observation data in the MVN formulation. These techniques, in combination with modern empirical ground‐motion models and correlation functions, provide a flexible framework for estimating a variety of IMs at arbitrary locations.

VVV high proper motion stars - I. The catalogue of bright KS ≤ 13.5 stars

NASA Astrophysics Data System (ADS)

Kurtev, R.; Gromadzki, M.; Beamín, J. C.; Folkes, S. L.; Pena Ramirez, K.; Ivanov, V. D.; Borissova, J.; Villanueva, V.; Minniti, D.; Mendez, R.; Lucas, P. W.; Smith, L. C.; Pinfield, D. J.; Kuhn, M. A.; Jones, H. R. A.; Antonova, A.; Yip, A. K. P.

2017-01-01

Knowledge of the stellar content near the Sun is important for a broad range of topics ranging from the search for planets to the study of Milky Way (MW) structure. The most powerful method for identifying potentially nearby stars is proper motion (PM) surveys. All old optical surveys avoid, or are at least substantially incomplete, near the Galactic plane. The depth and breadth of the `VISTA Variables in Vía Láctea' (VVV) near-IR survey significantly improves this situation. Taking advantage of the VVV survey data base, we have measured PMs in the densest regions of the MW bulge and southern plane in order to complete the census of nearby objects. We have developed a custom PM pipeline based on VVV catalogues from the Cambridge Astronomy Survey Unit, by comparing the first epoch of JHKS with the multi-epoch KS bands acquired later. Taking advantage of the large time baseline between the Two Micron All Sky Survey (2MASS) and the VVV observations, we also obtained 2MASS-VVV PMs. We present a near-IR PM catalogue for the whole area of the VVV survey, which includes 3003 moving stellar sources. All of these have been visually inspected and are real PM objects. Our catalogue is in very good agreement with the PM data supplied in IR catalogues outside the densest zone of the MW. The majority of the PM objects in our catalogue are nearby M-dwarfs, as expected. This new data base allows us to identify 57 common PM binary candidates, among which are two new systems within 30 pc of the Sun.

Optical observation of correlated motions in dihydrofolate reductase

NASA Astrophysics Data System (ADS)

Xu, Mengyang; Niessen, Katherine; Pace, James; Cody, Vivian; Markelz, Andrea

2015-03-01

Enzyme function relies on its structural flexibility to make conformational changes for substrate binding and product release. An example of a metabolic enzyme where such structural changes are vital is dihydrofolate reductase (DHFR). DHFR is essential in both prokaryotes and eukaryotes for the nucleotide biosynthesis by catalyzing the reduction of dihydrofolate to tetrahydrofolate. NMR dynamical measurements found large amplitude fast dynamics that could indicate rigid-body, twisting-hinge motion for ecDHFR that may mediate flux. The role of such long-range correlated motions in function was suggested by the observed sharp decrease in enzyme activity for the single point mutation G121V, which is remote from active sites. This decrease in activity may be caused by the mutation interfering with the long-range intramolecular vibrations necessary for rapid access to functional configurations. We use our new technique of crystal anisotropy terahertz microscopy (CATM), to observe correlated motions in ecDHFR crystals with the bonding of NADPH and methotrexate. We compare the measured intramolecular vibrational spectrum with calculations using normal mode analysis.

Conceptual Research of Lunar-based Earth Observation for Polar Glacier Motion

NASA Astrophysics Data System (ADS)

Ruan, Zhixing; Liu, Guang; Ding, Yixing

2016-07-01

The ice flow velocity of glaciers is important for estimating the polar ice sheet mass balance, and it is of great significance for studies into rising sea level under the background of global warming. However so far the long-term and global measurements of these macro-scale motion processes of the polar glaciers have hardly been achieved by Earth Observation (EO) technique from the ground, aircraft or satellites in space. This paper, facing the demand for space technology for large-scale global environmental change observation,especially the changes of polar glaciers, and proposes a new concept involving setting up sensors on the lunar surface and using the Moon as a platform for Earth observation, transmitting the data back to Earth. Lunar-based Earth observation, which enables the Earth's large-scale, continuous, long-term dynamic motions to be measured, is expected to provide a new solution to the problems mentioned above. According to the pattern and characteristics of polar glaciers motion, we will propose a comprehensive investigation of Lunar-based Earth observation with synthetic aperture radar (SAR). Via theoretical modeling and experimental simulation inversion, intensive studies of Lunar-based Earth observation for the glacier motions in the polar regions will be implemented, including the InSAR basics theory, observation modes of InSAR and optimization methods of their key parameters. It will be of a great help to creatively expand the EO technique system from space. In addition, they will contribute to establishing the theoretical foundation for the realization of the global, long-term and continuous observation for the glacier motion phenomena in the Antarctic and the Arctic.

Motion based parsing for video from observational psychology

NASA Astrophysics Data System (ADS)

Kokaram, Anil; Doyle, Erika; Lennon, Daire; Joyeux, Laurent; Fuller, Ray

2006-01-01

In Psychology it is common to conduct studies involving the observation of humans undertaking some task. The sessions are typically recorded on video and used for subjective visual analysis. The subjective analysis is tedious and time consuming, not only because much useless video material is recorded but also because subjective measures of human behaviour are not necessarily repeatable. This paper presents tools using content based video analysis that allow automated parsing of video from one such study involving Dyslexia. The tools rely on implicit measures of human motion that can be generalised to other applications in the domain of human observation. Results comparing quantitative assessment of human motion with subjective assessment are also presented, illustrating that the system is a useful scientific tool.

Proper horizontal photospheric flows below an eruptive filament

NASA Astrophysics Data System (ADS)

Schmieder, Brigitte; Mein, Pierre; Mein, Nicole; Roudier, Thierry; Chandra, Ramseh

An analysis of the proper motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track the granules as well as the large scale photospheric flows, was perfomed during three hours in a region containing a large filament channel on September 17, 2010. Supergranules were idenfied in the filament channel. Diverging flows inside the supergranules are similar in and out the filament channel. Using corks, we derived the passive scalar points and produced maps of cork distribution. The anchorage structures with the photosphere (feet) of the filament are located in the areas of converging flows with accumulations of corks. Averaging the velocity vectors for each latitude we defined a profile of the differential rotation. We conclude that the coupling between the convection and magnetic field in the photosphere is relatively strong. The filament experienced the convection motions through its feet. On a large scale point-of-view the differential rotation induced a shear of 0.1 km/s in the filament. On a small scale point-of-view convection motions favored the interaction/cancellation of the parasitic polarities at the base of the feet with the surrounding network explaining the brightenings,/jets and the eruption that were observed in the EUV filament.

OB Stars and Cepheids From the Gaia TGAS Catalogue: Test of their Distances and Proper Motions

NASA Astrophysics Data System (ADS)

Bobylev, Vadim V.; Bajkova, Anisa T.

2017-12-01

We consider young distant stars from the Gaia TGAS catalog. These are 250 classical Cepheids and 244 OB stars located at distances up to 4 kpc from the Sun. These stars are used to determine the Galactic rotation parameters using both trigonometric parallaxes and proper motions of the TGAS stars. In this case the considered stars have relative parallax errors less than 200%. Following the well-known statistical approach, we assume that the kinematic parameters found from the line-of-sight velocities Vr are less dependent on errors of distances than the found from the velocity components Vl. From values of the first derivative of the Galactic rotation angular velocity '0, found from the analysis of velocities Vr and Vl separately, the scale factor of distances is determined.We found that from the sample of Cepheids the scale of distances of the TGAS should be reduced by 3%, and from the sample of OB stars, on the contrary, the scale should be increased by 9%.

VizieR Online Data Catalog: Photometry and proper motions in Praesepe (Wang+, 2014)

NASA Astrophysics Data System (ADS)

Wang, P. F.; Chen, W. P.; Lin, C. C.; Pandey, A. K.; Huang, C. K.; Panwar, N.; Lee, C. H.; Tsai, M. F.; Tang, C.-H.; Goldman, B.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Grav, T.; Heasley, J. N.; Hodapp, K. W.; Huber, M. E.; Jedicke, R.; Kaiser, N.; Kudritzki, R.-P.; Luppino, G. A.; Lupton, R. H.; Magnier, E. A.; Metcalfe, N.; Monet, D. G.; Morgan, J. S.; Onaka, P. M.; Price, P. A.; Stubbs, C. W.; Sweeney, W.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

2016-08-01

Data used in this study include photometry and proper motion measurements within a 5° radius around the Praesepe center (R.A.=08h40m, decl.=+19°42', J2000). Archival data were taken from the 2MASS Point Sources Catalog (2MASS; cat. II/246), PPMXL (Roeser et al. 2010, cat. I/317), and Panoramic Survey Telescope And Rapid Response (Pan-STARRS). Pan-STARRS is a wide-field (7deg2) imaging system, with a 1.8m, f/4.4 telescope, equipped with a 1.4 giga-pixel camera. The prototype (PS1), located atop Haleakala, Maui, USA, has been patrolling the entire sky north of -30° declination since mid-2010 with a combination of gP1, rP1, iP1, zP1, and yP1 bands. The PS1 filters differ slightly from those of the SDSS. The gP1 filter extends 20nm redward of gSDSS for greater sensitivity and lower systematics for photometric redshift estimates. SDSS has no corresponding y filter (Tonry et al. 2012, cat. J/ApJ/750/99). Upon the completion of its 3.5yr mission by early 2014, PS1 will provide reliable photometry and astrometry. Table1 lists the properties of the 1040 candidates. (1 data file).

The absolute magnitudes of RR Lyraes from HIPPARCOS parallaxes and proper motions

NASA Astrophysics Data System (ADS)

Fernley, J.; Barnes, T. G.; Skillen, I.; Hawley, S. L.; Hanley, C. J.; Evans, D. W.; Solano, E.; Garrido, R.

1998-02-01

We have used HIPPARCOS proper motions and the method of Statistical Parallax to estimate the absolute magnitude of RR Lyrae stars. In addition we used the HIPPARCOS parallax of RR Lyrae itself to determine it's absolute magnitude. These two results are in excellent agreement with each other and give a zero-point for the RR Lyrae M_v,[Fe/H] relation of 0.77+/-0.15 at [Fe/H]=-1.53. This zero-point is in good agreement with that obtained recently by several groups using Baade-Wesselink methods which, averaged over the results from the different groups, gives M_v = 0.73+/-0.14 at [Fe/H]=-1.53. Taking the HIPPARCOS based zero-point and a value of 0.18+/-0.03 for the slope of the M_v,[Fe/H] relation from the literature we find firstly, the distance modulus of the LMC is 18.26+/-0.15 and secondly, the mean age of the Globular Clusters is 17.4+/-3.0 GYrs. These values are compared with recent estimates based on other "standard candles" that have also been calibrated with HIPPARCOS data. It is clear that, in addition to astrophysical problems, there are also problems in the application of HIPPARCOS data that are not yet fully understood. Table 1, which contains the basic data for the RR Lyraes, is available only at CDS. It may be retrieved via anonymous FTP at cdsarc.u-strasbg.fr (130.79.128.5) or via the Web at http://cdsweb.u-strasbg.fr/Abstract.html

Observations on the Proper Orthogonal Decomposition

NASA Technical Reports Server (NTRS)

Berkooz, Gal

1992-01-01

The Proper Orthogonal Decomposition (P.O.D.), also known as the Karhunen-Loeve expansion, is a procedure for decomposing a stochastic field in an L(2) optimal sense. It is used in diverse disciplines from image processing to turbulence. Recently the P.O.D. is receiving much attention as a tool for studying dynamics of systems in infinite dimensional space. This paper reviews the mathematical fundamentals of this theory. Also included are results on the span of the eigenfunction basis, a geometric corollary due to Chebyshev's inequality and a relation between the P.O.D. symmetry and ergodicity.

The seven sisters DANCe. II. Proper motions and the lithium rotation-activity connection for G and K Pleiades

NASA Astrophysics Data System (ADS)

Barrado, D.; Bouy, H.; Bouvier, J.; Moraux, E.; Sarro, L. M.; Bertin, E.; Cuillandre, J.-C.; Stauffer, J. R.; Lillo-Box, J.; Pollock, A.

2016-12-01

Context. Stellar clusters open the window to understanding stellar evolution and, in particular, the change with time and the dependence on mass of different stellar properties. As such, stellar clusters act as laboratories where different theories can be tested. Aims: We try to understand the origin of the connection between lithium depletion in F, G, and K stars, rotation and activity in the Pleiades open cluster. Methods: We have collected all the relevant data in the literature, including information regarding rotation period, binarity, and activity, and cross-matched this data with proper motions, multiwavelength photometry, and membership probability from the DANCe database. To avoid biases, we only included single members of the Pleiades with probabilities larger than 75% in the discussion. Results: The analysis confirms that there is a strong link between activity, rotation, and the lithium equivalent width excess, especially for the range Lum(bol) = 0.5-0.2L⊙ (about K2-K7 spectral types or 0.75-0.95 M⊙). Conclusions: It is not possible to disentangle these effects, but we cannot exclude that the observed lithium overabundance is partially an observational effect from enhanced activity owing to a large coverage by stellar spots induced by high rotation rates. Since a bona fide lithium enhancement is present in young, fast rotators, both activity and rotation should play a role in the lithium problem. Tables 1-3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A113

Polar motion interpretation using gravimetric observations

NASA Astrophysics Data System (ADS)

Seoane, L.; Bizouard, C.; Gambis, D.

2008-04-01

Polar motion is interpreted as the effect of i) the Earth’s inertia moment changes asso- ciated with the so-called mass term of the Earth’s angular momentum ii) the Earth’s relative angular momentum in the terrestrial frame. Thanks to the GRACE mission and in a lesser extent to LAGEOS missions, the mass term is determined since 2002, independently from any geophysical model. Besides the modeled excitations of the polar motion, i.e the atmospheric angular momentum (AAM), the Oceanic Angular Momentum (OAM), the Hydrological Angular Momentum (HAM), this gravimetric mass term is a new kind of information which can be matched to the observed excitation of the polar motion after removal of the effect of the relative angular momentum, mostly caused by the wind and the oceanic cur- rents. Such comparison, already performed by various authors, is updated for the last releases (RL04) of the gravity field changes i.e. those of the GFZ, CSR, JPL and explored for the mixed LAGEOS-GRACE solution of the GRGS. We confirm that a fair general agreement, especially for the y-component of the equatorial excitation. After removing the modeled oceanic and atmospheric excitations from the signals, we obtain the non-modeled excitation, mostly of hydrological nature; this allows us to compare them to the existing hydrological models, differences might comes from others Earth’s phenomena, for example, earthquakes.

Proper-motion age dating of the progeny of Nova Scorpii AD 1437.

PubMed

Shara, M M; Iłkiewicz, K; Mikołajewska, J; Pagnotta, A; Bode, M F; Crause, L A; Drozd, K; Faherty, J; Fuentes-Morales, I; Grindlay, J E; Moffat, A F J; Pretorius, M L; Schmidtobreick, L; Stephenson, F R; Tappert, C; Zurek, D

2017-08-30

'Cataclysmic variables' are binary star systems in which one star of the pair is a white dwarf, and which often generate bright and energetic stellar outbursts. Classical novae are one type of outburst: when the white dwarf accretes enough matter from its companion, the resulting hydrogen-rich atmospheric envelope can host a runaway thermonuclear reaction that generates a rapid brightening. Achieving peak luminosities of up to one million times that of the Sun, all classical novae are recurrent, on timescales of months to millennia. During the century before and after an eruption, the 'novalike' binary systems that give rise to classical novae exhibit high rates of mass transfer to their white dwarfs. Another type of outburst is the dwarf nova: these occur in binaries that have stellar masses and periods indistinguishable from those of novalikes but much lower mass-transfer rates, when accretion-disk instabilities drop matter onto the white dwarfs. The co-existence at the same orbital period of novalike binaries and dwarf novae-which are identical but for their widely varying accretion rates-has been a longstanding puzzle. Here we report the recovery of the binary star underlying the classical nova eruption of 11 March AD 1437 (refs 12, 13), and independently confirm its age by proper-motion dating. We show that, almost 500 years after a classical-nova event, the system exhibited dwarf-nova eruptions. The three other oldest recovered classical novae display nova shells, but lack firm post-eruption ages, and are also dwarf novae at present. We conclude that many old novae become dwarf novae for part of the millennia between successive nova eruptions.

On the origin of the Monoceros Ring - I. Kinematics, proper motions, and the nature of the progenitor

NASA Astrophysics Data System (ADS)

Guglielmo, Magda; Lane, Richard R.; Conn, Blair C.; Ho, Anna Y. Q.; Ibata, Rodrigo A.; Lewis, Geraint F.

2018-03-01

The Monoceros Ring (MRi) structure is an apparent stellar overdensity that has been postulated to entirely encircle the Galactic plane and has been variously described as being due to line-of-sight effects of the Galactic warp and flare or of extragalactic origin (via accretion). Despite being intensely scrutinized in the literature for more than a decade, no studies to date have been able to definitively uncover its origins. Here we use N-body simulations and a genetic algorithm to explore the parameter space for the initial position, orbital parameters, and, for the first time, the final location of a satellite progenitor. We fit our models to the latest Pan-STARRS data to determine whether an accretion scenario is capable of producing an in-plane ring-like structure matching the known parameters of the MRi. Our simulations produce streams that closely match the location, proper motion, and kinematics of the MRi structure. However, we are not able to reproduce the mass estimates from earlier studies based on Pan-STARRS data. Furthermore, in contrast to earlier studies, our best-fitting models are those for progenitors on retrograde orbits. If the MRi was produced by satellite accretion, we find that its progenitor has an initial mass upper limit of ˜1010 M⊙ and the remnant is likely located behind the Galactic bulge, making it difficult to locate observationally. While our models produce realistic MRi-like structures, we cannot definitively conclude that the MRi was produced by the accretion of a satellite galaxy.

Astrometric Observation of MACHO Gravitational Microlensing

NASA Technical Reports Server (NTRS)

Boden, A. F.; Shao, M.; Van Buren, D.

1997-01-01

This paper discusses the prospects for astrometric observation of MACHO gravitational microlensing events. We derive the expected astrometric observables for a simple microlensing event assuming a dark MACHO, and demonstrate that accurate astrometry can determine the lens mass, distance, and proper motion in a very general fashion.

THEMIS Observations of Unusual Bow Shock Motion, Attending a Transient Magnetospheric Event

NASA Technical Reports Server (NTRS)

Korotova, Galina; Sibeck, David; Omidi, N.; Angelopoulos, V.

2013-01-01

We present a multipoint case study of solar wind and magnetospheric observations during a transient magnetospheric compression at 2319 UT on October 15, 2008. We use high-time resolution magnetic field and plasma data from the THEMIS and GOES-11/12 spacecraft to show that this transient event corresponded to an abrupt rotation in the IMF orientation, a change in the location of the foreshock, and transient outward bow shock motion. We employ results from a global hybrid code model to reconcile the observations indicating transient inward magnetopause motion with the outward bow shock motion.

Absolute proper motions to B approximately 22.5: Evidence for kimematical substructure in halo field stars

NASA Technical Reports Server (NTRS)

Majewski, Steven R.; Munn, Jeffrey A.; Hawley, Suzanne L.

1994-01-01

Radial velocities have been obtained for six of nine stars identified on the basis of similar distances and common, extreme transverse velocities in the proper motion survey of Majewski (1992) as a candidate halo moving group at the north Galactic pole. These radial velocities correspond to velocities perpendicular to the Galactic plane which span the range -48 +/- 21 to -128 +/- 9 km/sec (but a smaller range, -48 +/- 21 to -86 +/- 19 km/sec, when only our own measurements are considered), significantly different than the expected distribution, with mean 0 km/sec, for a random sample of either halo or thick disk stars. The probability of picking such a set of radial velocities at random is less than 1%. Thus the radial velocity data support the hypothesis that these stars constitute part of a halo moving group or star stream at a distance of approximately 4-5 kpc above the Galactic plane. If real, this moving group is evidence for halo phase space substructure which may be the fossil remains of a destroyed globular cluster, Galactic satellite, or Searle & Zinn (1978) 'fragment.'

Strong motion observations and recordings from the great Wenchuan Earthquake

USGS Publications Warehouse

Li, X.; Zhou, Z.; Yu, H.; Wen, R.; Lu, D.; Huang, M.; Zhou, Y.; Cu, J.

2008-01-01

The National Strong Motion Observation Network System (NSMONS) of China is briefly introduced in this paper. The NSMONS consists of permanent free-field stations, special observation arrays, mobile observatories and a network management system. During the Wenchuan Earthquake, over 1,400 components of acceleration records were obtained from 460 permanent free-field stations and three arrays for topographical effect and structural response observation in the network system from the main shock, and over 20,000 components of acceleration records from strong aftershocks occurred before August 1, 2008 were also obtained by permanent free-field stations of the NSMONS and 59 mobile instruments quickly deployed after the main shock. The strong motion recordings from the main shock and strong aftershocks are summarized in this paper. In the ground motion recordings, there are over 560 components with peak ground acceleration (PGA) over 10 Gal, the largest being 957.7 Gal. The largest PGA recorded during the aftershock exceeds 300 Gal. ?? 2008 Institute of Engineering Mechanics, China Earthquake Administration and Springer-Verlag GmbH.

GAIA: A WINDOW TO LARGE-SCALE MOTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nusser, Adi; Branchini, Enzo; Davis, Marc, E-mail: adi@physics.technion.ac.il, E-mail: branchin@fis.uniroma3.it, E-mail: mdavis@berkeley.edu

2012-08-10

Using redshifts as a proxy for galaxy distances, estimates of the two-dimensional (2D) transverse peculiar velocities of distant galaxies could be obtained from future measurements of proper motions. We provide the mathematical framework for analyzing 2D transverse motions and show that they offer several advantages over traditional probes of large-scale motions. They are completely independent of any intrinsic relations between galaxy properties; hence, they are essentially free of selection biases. They are free from homogeneous and inhomogeneous Malmquist biases that typically plague distance indicator catalogs. They provide additional information to traditional probes that yield line-of-sight peculiar velocities only. Further, becausemore » of their 2D nature, fundamental questions regarding vorticity of large-scale flows can be addressed. Gaia, for example, is expected to provide proper motions of at least bright galaxies with high central surface brightness, making proper motions a likely contender for traditional probes based on current and future distance indicator measurements.« less

Decoding the origins of vertical land motions observed today at coasts

NASA Astrophysics Data System (ADS)

Pfeffer, J.; Spada, G.; Mémin, A.; Boy, J.-P.; Allemand, P.

2017-07-01

In recent decades, geodetic techniques have allowed detecting vertical land motions and sea-level changes of a few millimetres per year, based on measurements taken at the coast (tide gauges), on board of satellite platforms (satellite altimetry) or both (Global Navigation Satellite System). Here, contemporary vertical land motions are analysed from January 1993 to July 2013 at 849 globally distributed coastal sites. The vertical displacement of the coastal platform due to surface mass changes is modelled using elastic and viscoelastic Green's functions. Special attention is paid to the effects of glacial isostatic adjustment induced by past and present-day ice melting. Various rheological and loading parameters are explored to provide a set of scenarios that could explain the coastal observations of vertical land motions globally. In well-instrumented regions, predicted vertical land motions explain more than 80 per cent of the variance observed at scales larger than a few hundred kilometres. Residual vertical land motions show a strong local variability, especially in the vicinity of plate boundaries due to the earthquake cycle. Significant residual signals are also observed at scales of a few hundred kilometres over nine well-instrumented regions forming observation windows on unmodelled geophysical processes. This study highlights the potential of our multitechnique database to detect geodynamical processes, driven by anthropogenic influence, surface mass changes (surface loading and glacial isostatic adjustment) and tectonic activity (including the earthquake cycle, sediment and volcanic loading, as well as regional tectonic constraints). Future improvements should be aimed at densifying the instrumental network and at investigating more thoroughly the uncertainties associated with glacial isostatic adjustment models.

VizieR Online Data Catalog: 5 Galactic GC proper motions from Gaia DR1 (Watkins+, 2017)

NASA Astrophysics Data System (ADS)

Watkins, L. L.; van der Marel, R. P.

2017-11-01

We present a pilot study of Galactic globular cluster (GC) proper motion (PM) determinations using Gaia data. We search for GC stars in the Tycho-Gaia Astrometric Solution (TGAS) catalog from Gaia Data Release 1 (DR1), and identify five members of NGC 104 (47 Tucanae), one member of NGC 5272 (M3), five members of NGC 6121 (M4), seven members of NGC 6397, and two members of NGC 6656 (M22). By taking a weighted average of member stars, fully accounting for the correlations between parameters, we estimate the parallax (and, hence, distance) and PM of the GCs. This provides a homogeneous PM study of multiple GCs based on an astrometric catalog with small and well-controlled systematic errors and yields random PM errors similar to existing measurements. Detailed comparison to the available Hubble Space Telescope (HST) measurements generally shows excellent agreement, validating the astrometric quality of both TGAS and HST. By contrast, comparison to ground-based measurements shows that some of those must have systematic errors exceeding the random errors. Our parallax estimates have uncertainties an order of magnitude larger than previous studies, but nevertheless imply distances consistent with previous estimates. By combining our PM measurements with literature positions, distances, and radial velocities, we measure Galactocentric space motions for the clusters and find that these also agree well with previous analyses. Our analysis provides a framework for determining more accurate distances and PMs of Galactic GCs using future Gaia data releases. This will provide crucial constraints on the near end of the cosmic distance ladder and provide accurate GC orbital histories. (4 data files).

Calculating observables in inhomogeneous cosmologies. Part I: general framework

NASA Astrophysics Data System (ADS)

Hellaby, Charles; Walters, Anthony

2018-02-01

We lay out a general framework for calculating the variation of a set of cosmological observables, down the past null cone of an arbitrarily placed observer, in a given arbitrary inhomogeneous metric. The observables include redshift, proper motions, area distance and redshift-space density. Of particular interest are observables that are zero in the spherically symmetric case, such as proper motions. The algorithm is based on the null geodesic equation and the geodesic deviation equation, and it is tailored to creating a practical numerical implementation. The algorithm provides a method for tracking which light rays connect moving objects to the observer at successive times. Our algorithm is applied to the particular case of the Szekeres metric. A numerical implementation has been created and some results will be presented in a subsequent paper. Future work will explore the range of possibilities.

The case for 6-component ground motion observations in planetary seismology

NASA Astrophysics Data System (ADS)

Joshi, Rakshit; van Driel, Martin; Donner, Stefanie; Nunn, Ceri; Wassermann, Joachim; Igel, Heiner

2017-04-01

The imminent INSIGHT mission will place a single seismic station on Mars to learn more about the structure of the Martian interior. Due to cost and difficulty, only single stations are currently feasible for planetary missions. We show that future single station missions should also measure rotational ground motions, in addition to the classic 3 components of translational motion. The joint, collocated, 6 component (6C) observations offer access to additional information that can otherwise only be obtained through seismic array measurements or are associated with large uncertainties. An example is the access to local phase velocity information from measurements of amplitude ratios of translations and rotations. When surface waves are available, this implies (in principle) that 1D velocity models can be estimated from Love wave dispersion curves. In addition, rotational ground motion observations can distinguish between Love and Rayleigh waves as well as S and P type motions. Wave propagation directions can be estimated by maximizing (or minimizing) coherence between translational and rotational motions. In combination with velocity-depth estimates, locations of seismic sources can be determined from a single station with little or no prior knowledge of the velocity structure. We demonstrate these points with both theoretical and real data examples using the vertical component of motion from ring laser recordings at Wettzell and all components of motion from the ROMY ring near Munich. Finally, we present the current state of technology concerning portable rotation sensors and discuss the relevance to planetary seismology.

Identifications and limited spectroscopy for Luyten common proper motion stars with probable white dwarf components. I - Pair brighter than 17th magnitude

NASA Technical Reports Server (NTRS)

Oswalt, Terry D.; Hintzen, Paul M.; Luyten, Willem J.

1988-01-01

Identifications are provided for 103 bright Luyten common proper motion (CPM) stellar systems with m(pg) less than 17.0 mag containing likely white dwarf (WD) components. New spectral types are presented for 55 components, and spectral types for 51 more are available in the literature. With the CPM systems previously published by Giclas et al. (1978), the Luyten stars provide a uniform sample of nearly 200 pairs or multiples brighter than 17h magnitude. Selection effects biasing the combined samples are discussed; in particular, evidence is presented that fewer than 1 percent of wide WD binaries have been detected.

N-body modeling of globular clusters: detecting intermediate-mass black holes by non-equipartition in HST proper motions

NASA Astrophysics Data System (ADS)

Trenti, Michele

2010-09-01

Intermediate Mass Black Holes {IMBHs} are objects of considerable astrophysical significance. They have been invoked as possible remnants of Population III stars, precursors of supermassive black holes, sources of ultra-luminous X-ray emission, and emitters of gravitational waves. The centers of globular clusters, where they may have formed through runaway collapse of massive stars, may be our best chance of detecting them. HST studies of velocity dispersions have provided tentative evidence, but the measurements are difficult and the results have been disputed. It is thus important to explore and develop additional indicators of the presence of an IMBH in these systems. In a Cycle 16 theory project we focused on the fingerprints of an IMBH derived from HST photometry. We showed that an IMBH leads to a detectable quenching of mass segregation. Analysis of HST-ACS data for NGC 2298 validated the method, and ruled out an IMBH of more than 300 solar masses. We propose here to extend the search for IMBH signatures from photometry to kinematics. The velocity dispersion of stars in collisionally relaxed stellar systems such as globular clusters scales with main sequence mass as sigma m^alpha. A value alpha = -0.5 corresponds to equipartition. Mass-dependent kinematics can now be measured from HST proper motion studies {e.g., alpha = -0.21 for Omega Cen}. Preliminary analysis shows that the value of alpha can be used as indicator of the presence of an IMBH. In fact, the quenching of mass segregation is a result of the degree of equipartition that the system attains. However, detailed numerical simulations are required to quantify this. Therefore we propose {a} to carry out a new, larger set of realistic N-body simulations of star clusters with IMBHs, primordial binaries and stellar evolution to predict in detail the expected kinematic signatures and {b} to compare these predictions to datasets that are {becoming} available. Considerable HST resources have been invested in

Observing tectonic plate motions and deformations from satellite laser ranging

NASA Technical Reports Server (NTRS)

Christodoulidis, D. C.; Smith, D. E.; Kolenkiewicz, R.; Klosko, S. M.; Torrence, M. H.

1985-01-01

The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.

Documentation for the machine readable version of the Yale Catalogue of the Positions and Proper Motions of Stars between Declinations -60 deg and -70 deg (Fallon 1983)

NASA Technical Reports Server (NTRS)

Roman, N. G.; Warren, W. H., Jr.

1984-01-01

The machine-readable, character-coded version of the catalog, as it is currently being distributed from the Astronomical Data Center(ADC), is described. The format and data provided in the magnetic tape version differ somewhat from those of the published catalog, which was also produced from a tape prepared at the ADC. The primary catalog data are positions and proper motions (equinox 1950.0) for 14597 stars.

VizieR Online Data Catalog: Robo-AO observed cool subdwarf companions (Ziegler+, 2015)

NASA Astrophysics Data System (ADS)

Ziegler, C.; Law, N. M.; Baranec, C.; Riddle, R. L.; Fuchs, J. T.

2017-09-01

We selected targets from the 564 spectral type F- through M-subdwarf candidates studied by Marshall (2007, J/AJ/134/778). These targets were selected from the New Luyten Two-Tenths catalog (NLTT; Luyten, 1979nlcs.book.....L; Luyten & Hughes 1980, Proper-Motion Survey with the Forty-Eight Inch Schmidt Telescope LV First Supplement to the NLTT Catalogue (Minneapolis, MN: Univ. Minnesota Press)) of high proper motion stars (>0.18 arcsec/yr) using a reduced proper motion diagram (RPM). Of the 552 subdwarfs confirmed by Marshall, a randomly selected sample of 348 G-, K-, and M-subdwarfs were observed by Robo-AO when available between other high priority surveys. We obtained high-angular-resolution images of the 348 subdwarfs during 32 separate nights of observations between 2012 September 3 and 2013 August 21 (UT). The observations were performed using the Robo-AO laser adaptive optics system (Riddle et al. 2012SPIE.8447E..2OR; Baranec et al. 2013, J. Visualized Exp. 72 e50021; 2014ApJ...790L...8B) mounted on the Palomar 60 inch telescope. (1 data file).

Sub-daily sea ice motion and deformation from RADARSAT observations

NASA Technical Reports Server (NTRS)

Kwok, R.; Cunningham, G. F.

2003-01-01

We find a persistent level of oscillatory sea ice motion and deformation, superimposed on the large-scale wind-driven field, in May 2002 (spring) and February 2003 (mid-winter), in the high Arctic over a region centered at approx.(85degreeN, 135degreeW). At this latitude, the RADARSAT wide-swath SAR coverage provides 4??equential observations every day, for ice motion retrieval, with a sampling interval at the orbital period of approx. 101 minutes.

Wideband Motion Control by Position and Acceleration Input Based Disturbance Observer

NASA Astrophysics Data System (ADS)

Irie, Kouhei; Katsura, Seiichiro; Ohishi, Kiyoshi

The disturbance observer can observe and suppress the disturbance torque within its bandwidth. Recent motion systems begin to spread in the society and they are required to have ability to contact with unknown environment. Such a haptic motion requires much wider bandwidth. However, since the conventional disturbance observer attains the acceleration response by the second order derivative of position response, the bandwidth is limited due to the derivative noise. This paper proposes a novel structure of a disturbance observer. The proposed disturbance observer uses an acceleration sensor for enlargement of bandwidth. Generally, the bandwidth of an acceleration sensor is from 1Hz to more than 1kHz. To cover DC range, the conventional position sensor based disturbance observer is integrated. Thus, the performance of the proposed Position and Acceleration input based disturbance observer (PADO) is superior to the conventional one. The PADO is applied to position control (infinity stiffness) and force control (zero stiffness). The numerical and experimental results show viability of the proposed method.

As time passes by: Observed motion-speed and psychological time during video playback.

PubMed

Nyman, Thomas Jonathan; Karlsson, Eric Per Anders; Antfolk, Jan

2017-01-01

Research shows that psychological time (i.e., the subjective experience and assessment of the passage of time) is malleable and that the central nervous system re-calibrates temporal information in accordance with situational factors so that psychological time flows slower or faster. Observed motion-speed (e.g., the visual perception of a rolling ball) is an important situational factor which influences the production of time estimates. The present study examines previous findings showing that observed slow and fast motion-speed during video playback respectively results in over- and underproductions of intervals of time. Here, we investigated through three separate experiments: a) the main effect of observed motion-speed during video playback on a time production task and b) the interactive effect of the frame rate (frames per second; fps) and motion-speed during video playback on a time production task. No main effect of video playback-speed or interactive effect between video playback-speed and frame rate was found on time production.

As time passes by: Observed motion-speed and psychological time during video playback

PubMed Central

Karlsson, Eric Per Anders; Antfolk, Jan

2017-01-01

Research shows that psychological time (i.e., the subjective experience and assessment of the passage of time) is malleable and that the central nervous system re-calibrates temporal information in accordance with situational factors so that psychological time flows slower or faster. Observed motion-speed (e.g., the visual perception of a rolling ball) is an important situational factor which influences the production of time estimates. The present study examines previous findings showing that observed slow and fast motion-speed during video playback respectively results in over- and underproductions of intervals of time. Here, we investigated through three separate experiments: a) the main effect of observed motion-speed during video playback on a time production task and b) the interactive effect of the frame rate (frames per second; fps) and motion-speed during video playback on a time production task. No main effect of video playback-speed or interactive effect between video playback-speed and frame rate was found on time production. PMID:28614353

Observing the overall rocking motion of a protein in a crystal

NASA Astrophysics Data System (ADS)

Ma, Peixiang; Xue, Yi; Coquelle, Nicolas; Haller, Jens D.; Yuwen, Tairan; Ayala, Isabel; Mikhailovskii, Oleg; Willbold, Dieter; Colletier, Jacques-Philippe; Skrynnikov, Nikolai R.; Schanda, Paul

2015-10-01

The large majority of three-dimensional structures of biological macromolecules have been determined by X-ray diffraction of crystalline samples. High-resolution structure determination crucially depends on the homogeneity of the protein crystal. Overall `rocking' motion of molecules in the crystal is expected to influence diffraction quality, and such motion may therefore affect the process of solving crystal structures. Yet, so far overall molecular motion has not directly been observed in protein crystals, and the timescale of such dynamics remains unclear. Here we use solid-state NMR, X-ray diffraction methods and μs-long molecular dynamics simulations to directly characterize the rigid-body motion of a protein in different crystal forms. For ubiquitin crystals investigated in this study we determine the range of possible correlation times of rocking motion, 0.1-100 μs. The amplitude of rocking varies from one crystal form to another and is correlated with the resolution obtainable in X-ray diffraction experiments.

Ages of the Bulge Globular Clusters NGC 6522 and NGC 6626 (M28) from HST Proper-motion-cleaned Color–Magnitude Diagrams

NASA Astrophysics Data System (ADS)

Kerber, L. O.; Nardiello, D.; Ortolani, S.; Barbuy, B.; Bica, E.; Cassisi, S.; Libralato, M.; Vieira, R. G.

2018-01-01

Bulge globular clusters (GCs) with metallicities [Fe/H] ≲ ‑1.0 and blue horizontal branches are candidates to harbor the oldest populations in the Galaxy. Based on the analysis of HST proper-motion-cleaned color–magnitude diagrams in filters F435W and F625W, we determine physical parameters for the old bulge GCs NGC 6522 and NGC 6626 (M28), both with well-defined blue horizontal branches. We compare these results with similar data for the inner halo cluster NGC 6362. These clusters have similar metallicities (‑1.3 ≤ [Fe/H] ≤ ‑1.0) obtained from high-resolution spectroscopy. We derive ages, distance moduli, and reddening values by means of statistical comparisons between observed and synthetic fiducial lines employing likelihood statistics and the Markov chain Monte Carlo method. The synthetic fiducial lines were generated using α-enhanced BaSTI and Dartmouth stellar evolutionary models, adopting both canonical (Y ∼ 0.25) and enhanced (Y ∼ 0.30–0.33) helium abundances. RR Lyrae stars were employed to determine the HB magnitude level, providing an independent indicator to constrain the apparent distance modulus and the helium enhancement. The shape of the observed fiducial line could be compatible with some helium enhancement for NGC 6522 and NGC 6626, but the average magnitudes of RR Lyrae stars tend to rule out this hypothesis. Assuming canonical helium abundances, BaSTI and Dartmouth models indicate that all three clusters are coeval, with ages between ∼12.5 and 13.0 Gyr. The present study also reveals that NGC 6522 has at least two stellar populations, since its CMD shows a significantly wide subgiant branch compatible with 14% ± 2% and 86% ± 5% for first and second generations, respectively. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute.

Sensory conflict in motion sickness: An observer theory approach

NASA Technical Reports Server (NTRS)

Oman, Charles M.

1989-01-01

Motion sickness is the general term describing a group of common nausea syndromes originally attributed to motion-induced cerebral ischemia, stimulation of abdominal organ afferent, or overstimulation of the vestibular organs of the inner ear. Sea-, car-, and airsicknesses are the most commonly experienced examples. However, the discovery of other variants such as Cinerama-, flight simulator-, spectacle-, and space sickness in which the physical motion of the head and body is normal or absent has led to a succession of sensory conflict theories which offer a more comprehensive etiologic perspective. Implicit in the conflict theory is the hypothesis that neutral and/or humoral signals originate in regions of the brain subversing spatial orientation, and that these signals somehow traverse to other centers mediating sickness symptoms. Unfortunately, the present understanding of the neurophysiological basis of motion sickness is far from complete. No sensory conflict neuron or process has yet been physiologically identified. To what extent can the existing theory be reconciled with current knowledge of the physiology and pharmacology of nausea and vomiting. The stimuli which causes sickness, synthesizes a contemporary Observer Theory view of the Sensory Conflict hypothesis are reviewed, and a revised model for the dynamic coupling between the putative conflict signals and nausea magnitude estimates is presented. The use of quantitative models for sensory conflict offers a possible new approach to improving the design of visual and motion systems for flight simulators and other virtual environment display systems.

Globular Cluster Orbits from HST Proper Motions: Constraining the Formation and Mass of the Milky Way Halo

NASA Astrophysics Data System (ADS)

Sohn, S. Tony; Van Der Marel, Roeland P.; Deason, Alis J.; Bellini, Andrea; Besla, Gurtina; Watkins, Laura

2016-06-01

The globular cluster (GC) system of the Milky Way (MW) provides important information on the MW's present structure and past evolution. GCs in the halo are particularly useful tracers; because of their long dynamical timescales, their orbits retain imprints of their origin or accretion history. Full 3D motions are required to calculate past orbits. While most GCs have known line of sight velocities, accurate proper motion (PM) measurements are currently available for only a few halo GCs. Our goal is to create the first high-quality PM database for halo GCs. We have identified suitable 1st-epoch data in the HST Archive for 20 halo GCs at 10-100 kpc from the Galactic Center. We are in the process of obtaining the necessary 2nd-epoch data to determine absolute PMs of the target GCs through our HST program GO-14235. We will use the same advanced astrometric techniques that allowed us to measure the PMs of M31 and Leo I. Previous studies of the halo GC system based on e.g., stellar populations, metallicities, RR Lyrae properties, and structural properties have revealed a dichotomy between old and young halo GCs. This may reflect distinct formation scenarios (in situ vs. accreted). Orbit calculations based on our PMs will directly test this. The PMs will also yield the best handle yet on the velocity anisotropy profile of any tracer population in the halo. This will resolve the mass-anisotropy degeneracy to provide an improved estimate of the MW mass, which is at present poorly known. In summary, our project will deliver the first accurate PMs for halo GCs, and will significantly increase our understanding of the formation, evolution, and mass of the MW.

Observation of Brownian motion in liquids at short times: instantaneous velocity and memory loss.

PubMed

Kheifets, Simon; Simha, Akarsh; Melin, Kevin; Li, Tongcang; Raizen, Mark G

2014-03-28

Measurement of the instantaneous velocity of Brownian motion of suspended particles in liquid probes the microscopic foundations of statistical mechanics in soft condensed matter. However, instantaneous velocity has eluded experimental observation for more than a century since Einstein's prediction of the small length and time scales involved. We report shot-noise-limited, high-bandwidth measurements of Brownian motion of micrometer-sized beads suspended in water and acetone by an optical tweezer. We observe the hydrodynamic instantaneous velocity of Brownian motion in a liquid, which follows a modified energy equipartition theorem that accounts for the kinetic energy of the fluid displaced by the moving bead. We also observe an anticorrelated thermal force, which is conventionally assumed to be uncorrelated.

Motion Tree Delineates Hierarchical Structure of Protein Dynamics Observed in Molecular Dynamics Simulation

PubMed Central

Moritsugu, Kei; Koike, Ryotaro; Yamada, Kouki; Kato, Hiroaki; Kidera, Akinori

2015-01-01

Molecular dynamics (MD) simulations of proteins provide important information to understand their functional mechanisms, which are, however, likely to be hidden behind their complicated motions with a wide range of spatial and temporal scales. A straightforward and intuitive analysis of protein dynamics observed in MD simulation trajectories is therefore of growing significance with the large increase in both the simulation time and system size. In this study, we propose a novel description of protein motions based on the hierarchical clustering of fluctuations in the inter-atomic distances calculated from an MD trajectory, which constructs a single tree diagram, named a “Motion Tree”, to determine a set of rigid-domain pairs hierarchically along with associated inter-domain fluctuations. The method was first applied to the MD trajectory of substrate-free adenylate kinase to clarify the usefulness of the Motion Tree, which illustrated a clear-cut dynamics picture of the inter-domain motions involving the ATP/AMP lid and the core domain together with the associated amplitudes and correlations. The comparison of two Motion Trees calculated from MD simulations of ligand-free and -bound glutamine binding proteins clarified changes in inherent dynamics upon ligand binding appeared in both large domains and a small loop that stabilized ligand molecule. Another application to a huge protein, a multidrug ATP binding cassette (ABC) transporter, captured significant increases of fluctuations upon binding a drug molecule observed in both large scale inter-subunit motions and a motion localized at a transmembrane helix, which may be a trigger to the subsequent structural change from inward-open to outward-open states to transport the drug molecule. These applications demonstrated the capabilities of Motion Trees to provide an at-a-glance view of various sizes of functional motions inherent in the complicated MD trajectory. PMID:26148295

Characterizing the Cool KOIs. III. KOI 961: A Small Star with Large Proper Motion and Three Small Planets

NASA Astrophysics Data System (ADS)

Muirhead, Philip S.; Johnson, John Asher; Apps, Kevin; Carter, Joshua A.; Morton, Timothy D.; Fabrycky, Daniel C.; Pineda, John Sebastian; Bottom, Michael; Rojas-Ayala, Bárbara; Schlawin, Everett; Hamren, Katherine; Covey, Kevin R.; Crepp, Justin R.; Stassun, Keivan G.; Pepper, Joshua; Hebb, Leslie; Kirby, Evan N.; Howard, Andrew W.; Isaacson, Howard T.; Marcy, Geoffrey W.; Levitan, David; Diaz-Santos, Tanio; Armus, Lee; Lloyd, James P.

2012-03-01

We characterize the star KOI 961, an M dwarf with transit signals indicative of three short-period exoplanets discovered by the Kepler mission. We proceed by comparing KOI 961 to Barnard's Star, a nearby, well-characterized mid-M dwarf. We compare colors, optical and near-infrared spectra, and find remarkable agreement between the two, implying similar effective temperatures and metallicities. Both are metal-poor compared to the Solar neighborhood, have low projected rotational velocity, high absolute radial velocity, large proper motion, and no quiescent Hα emission—all of which are consistent with being old M dwarfs. We combine empirical measurements of Barnard's Star and expectations from evolutionary isochrones to estimate KOI 961's mass (0.13 ± 0.05 M ⊙), radius (0.17 ± 0.04 R ⊙), and luminosity (2.40 × 10-3.0 ± 0.3 L ⊙). We calculate KOI 961's distance (38.7 ± 6.3 pc) and space motions, which, like Barnard's Star, are consistent with a high scale-height population in the Milky Way. We perform an independent multi-transit fit to the public Kepler light curve and significantly revise the transit parameters for the three planets. We calculate the false-positive probability for each planet candidate, and find a less than 1% chance that any one of the transiting signals is due to a background or hierarchical eclipsing binary, validating the planetary nature of the transits. The best-fitting radii for all three planets are less than 1 R ⊕, with KOI 961.03 being Mars-sized (RP = 0.57 ± 0.18 R ⊕), and they represent some of the smallest exoplanets detected to date.

DISCOVERY OF FOUR HIGH PROPER MOTION L DWARFS, INCLUDING A 10 pc L DWARF AT THE L/T TRANSITION {sup ,}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castro, Philip J.; Gizis, John E.; Harris, Hugh C.

2013-10-20

We discover four high proper motion L dwarfs by comparing the Wide-field Infrared Survey Explorer (WISE) to the Two Micron All Sky Survey. WISE J140533.32+835030.5 is an L dwarf at the L/T transition with a proper motion of 0.85 ± 0.''02 yr{sup –1}, previously overlooked due to its proximity to a bright star (V ≈ 12 mag). From optical spectroscopy we find a spectral type of L8, and from moderate-resolution J band spectroscopy we find a near-infrared spectral type of L9. We find WISE J140533.32+835030.5 to have a distance of 9.7 ± 1.7 pc, bringing the number of L dwarfsmore » at the L/T transition within 10 pc from six to seven. WISE J040137.21+284951.7, WISE J040418.01+412735.6, and WISE J062442.37+662625.6 are all early L dwarfs within 25 pc, and were classified using optical and low-resolution near-infrared spectra. WISE J040418.01+412735.6 is an L2 pec (red) dwarf, a member of the class of unusually red L dwarfs. We use follow-up optical and low-resolution near-infrared spectroscopy to classify a previously discovered fifth object WISEP J060738.65+242953.4 as an (L8 Opt/L9 NIR), confirming it as an L dwarf at the L/T transition within 10 pc. WISEP J060738.65+242953.4 shows tentative CH{sub 4} in the H band, possibly the result of unresolved binarity with an early T dwarf, a scenario not supported by binary spectral template fitting. If WISEP J060738.65+242953.4 is a single object, it represents the earliest onset of CH{sub 4} in the H band of an L/T transition dwarf in the SpeX Library. As very late L dwarfs within 10 pc, WISE J140533.32+835030.5 and WISEP J060738.65+242953.4 will play a vital role in resolving outstanding issues at the L/T transition.« less

Thunder-induced ground motions: 1. Observations

NASA Astrophysics Data System (ADS)

Lin, Ting-L.; Langston, Charles A.

2009-04-01

Acoustic pressure from thunder and its induced ground motions were investigated using a small array consisting of five three-component short-period surface seismometers, a three-component borehole seismometer, and five infrasound microphones. We used the array to constrain wave parameters of the incident acoustic and seismic waves. The incident slowness differences between acoustic pressure and ground motions suggest that ground reverberations were first initiated somewhat away from the array. Using slowness inferred from ground motions is preferable to obtain the seismic source parameters. We propose a source equalization procedure for acoustic/seismic deconvolution to generate the time domain transfer function, a procedure similar to that of obtaining teleseismic earthquake receiver functions. The time domain transfer function removes the incident pressure time history from the seismogram. An additional vertical-to-radial ground motion transfer function was used to identify the Rayleigh wave propagation mode of induced seismic waves complementing that found using the particle motions and amplitude variations in the borehole. The initial motions obtained by the time domain transfer functions suggest a low Poisson's ratio for the near-surface layer. The acoustic-to-seismic transfer functions show a consistent reverberation series at frequencies near 5 Hz. This gives an empirical measure of site resonance that depends on the ratio of the layer velocity to layer thickness for earthquake P and S waves. The time domain transfer function approach by transferring a spectral division into the time domain provides an alternative method for studying acoustic-to-seismic coupling.

Review: Progress in rotational ground-motion observations from explosions and local earthquakes in Taiwan

USGS Publications Warehouse

Lee, William H K.; Huang, Bor-Shouh; Langston, Charles A.; Lin, Chin-Jen; Liu, Chun-Chi; Shin, Tzay-Chyn; Teng, Ta-Liang; Wu, Chien-Fu

2009-01-01

Rotational motions generated by large earthquakes in the far field have been successfully measured, and observations agree well with the classical elasticity theory. However, recent rotational measurements in the near field of earthquakes in Japan and in Taiwan indicate that rotational ground motions are 10 to 100 times larger than expected from the classical elasticity theory. The near-field strong-motion records of the 1999 Mw 7.6 Chi-Chi, Taiwan, earthquake suggest that the ground motions along the 100 km rupture are complex. Some rather arbitrary baseline corrections are necessary in order to obtain reasonable displacement values from double integration of the acceleration data. Because rotational motions can contaminate acceleration observations due to the induced perturbation of the Earth’s gravitational field, we started a modest program to observe rotational ground motions in Taiwan.Three papers have reported the rotational observations in Taiwan: (1) at the HGSD station (Liu et al., 2009), (2) at the N3 site from two TAiwan Integrated GEodynamics Research (TAIGER) explosions (Lin et al., 2009), and (3) at the Taiwan campus of the National Chung-Cheng University (NCCU) (Wu et al., 2009). In addition, Langston et al. (2009) reported the results of analyzing the TAIGER explosion data. As noted by several authors before, we found a linear relationship between peak rotational rate (PRR in mrad/sec) and peak ground acceleration (PGA in m/sec2) from local earthquakes in Taiwan, PRR=0.002+1.301 PGA, with a correlation coefficient of 0.988.

What motion is: William Neile and the laws of motion.

PubMed

Kemeny, Max

2017-07-01

In 1668-1669 William Neile and John Wallis engaged in a protracted correspondence regarding the nature of motion. Neile was unhappy with the laws of motion that had been established by the Royal Society in three papers published in 1668, deeming them not explanations of motion at all, but mere descriptions. Neile insisted that science could not be informative without a discussion of causes, meaning that Wallis's purely kinematic account of collision could not be complete. Wallis, however, did not consider Neile's objections to his work to be serious. Rather than engage in a discussion of the proper place of natural philosophy in science, Wallis decided to show how Neile's preferred treatment of motion lead to absurd conclusions. This dispute is offered as a case study of dispute resolution within the early Royal Society.

Reconstructing the past outburst history of Eta Carinae from WFPC2 proper motions

NASA Astrophysics Data System (ADS)

Smith, Nathan

2016-10-01

The HST archive contains multiple epochs of WFPC2 images of the nebula around Eta Carinae taken over a 15-year timespan, although only the earliest few years of data have been analyzed and published. The fact that all these images were taken with the same instrument, with the same pixel sampling and field distortion, makes them an invaluable resource for accurately measuring the expanding ejecta. The goal of a previously accepted AR proposal was to analyze the full set of appropriate continuum-filter HST images to place precise constraints on the avereage ejection date of the Homunculus Nebula; this analysis is now complete (Smith et al 2016) and the nebula appears to have been ejected in the second half of 1847. Here we propose to continue this project by constraining the motion of the more extended and much older Outer Ejecta around Eta Carinae. Older material outside the main bipolar nebula traces previous major outbursts of the star with no recorded historical observations. We propose an ambitious reduction and analysis of the complete WFPC2 imaging dataset of Eta Car. These data can reconstruct its violent mass-loss history over the past thousand years. We have already started this by analyzing two epochs of ACS F658N images, and astonishingly, these data suggested two previous eruptions in the 13th and 15th centuries assuming ballistic motion. WFPC2 images will extend the baseline by 10 yr, and critically, more than 2 epochs allow us to measure any deceleration in the ejecta. We will also analyze Doppler shifts in ground-based spectra in order to reconstruct the 3D geometry of past mass ejection. This AR proposal will fund the final year of a PhD thesis.

Rotational Motions from Teleseismic Events - Modelling and Observations

NASA Astrophysics Data System (ADS)

Schuberth, B.; Igel, H.; Wassermann, J.; Cochard, A.; Schreiber, U.

2004-12-01

Currently only ring lasers technology is capable of recording rotational motions resulting from earthquakes with a sensitivity and frequency band that are interesting for broadband seismology. One of those instruments is located at the Geodetic observatory in Wettzell/Germany. Here we present theoretical studies of rotational motions simulated with different Earth models and comparisons with several observations at the Wettzell ring laser. The 3-D global simulations were performed with the Spectral Element Method (Komatitsch and Tromp 2002a,b), that was modified to also allow the output of rotational seismograms. The Earth models used in these simulations range from simple radially symmetric ones, such as PREM, to more complex models including 3D velocity structures, attenuation and geometric effects like topography and bathymetry. Thus, by comparison of the theoretical rotation rates with the ring laser data we show how the results converge to the observed rotation rates when using more realistic Earth models. In a second step we compare rotation rates to the transverse component of translational acceleration both obtained from simulations with 3D velocity structures in crust and mantle. As expected from theory - under the assumption of plane wave propagation - those two signals should be in phase and scale linearly with the phase velocity. Using this relation, it is possible to determine the local phase velocity of transverse signals from collocated measurments of rotations and transverse accelerations. We compare the estimated phase velocities with those observed in a temporary seismic array installed around the ring laser.

Near-inertial motions in the Brazil Current at 24°S-36°S: Observations by satellite tracked drifters

NASA Astrophysics Data System (ADS)

Assireu, Arcilan T.; Dauhut, Thibaut; dos Santos, Francisco A.; Lorenzzetti, João A.

2017-08-01

Increased spatial and temporal resolution of recent observations and modeling have pointed out the importance of small scale structures (in the range of 1-50 km) for the mixing processes in the ocean. Based on high-frequency drifter measurements, we show here that the near-inertial currents (NICs) can contribute significantly to the surface kinetic energy in the Brazil Current (BC) region and, therefore, should be properly taken into account in the studies of transport and mixing processes. To characterize these submesoscale features, we examine the current response to the wind forcing in the Brazilian ocean margin between 24°S and 36°S using 3-hourly sampled trajectories of satellite-tracked drifters. Our results indicate a preference for anti-cyclonic circular motions, with a rotating period close to the local inertial period, consistent with near-inertial motions in the Southern Hemisphere (SH). Wind stress time series, from three months of wind measurements, along with synoptic weather charts, are used to relate the observed NICs to the atmospheric forcing. During SH spring, NICs occur in 4.7-15 day bursts and account for 15-45% of the total surface current variance. This intermittency is related to atmospheric cold frontal passages, low pressure systems, and sea breeze/land breeze circulations. The predominance of NICs south of 28°S appears to be related to the increased Effective Inertial Frequency (EIF), which is the inertial frequency changed by the sub-inertial background flow.

Evidence of small-scale magnetic concentrations dragged by vortex motion of solar photospheric plasma

NASA Astrophysics Data System (ADS)

Balmaceda, L.; Vargas Domínguez, S.; Palacios, J.; Cabello, I.; Domingo, V.

2010-04-01

Vortex-type motions have been measured by tracking bright points in high-resolution observations of the solar photosphere. These small-scale motions are thought to be determinant in the evolution of magnetic footpoints and their interaction with plasma and therefore likely to play a role in heating the upper solar atmosphere by twisting magnetic flux tubes. We report the observation of magnetic concentrations being dragged towards the center of a convective vortex motion in the solar photosphere from high-resolution ground-based and space-borne data. We describe this event by analyzing a series of images at different solar atmospheric layers. By computing horizontal proper motions, we detect a vortex whose center appears to be the draining point for the magnetic concentrations detected in magnetograms and well-correlated with the locations of bright points seen in G-band and CN images.

Motions in Prominence Barbs Observed on the Solar Limb

NASA Astrophysics Data System (ADS)

Kucera, T. A.; Ofman, L.; Tarbell, T. D.

2018-06-01

We analyze and discuss an example of prominence barbs observed on the limb on 2016 January 7 by the Hinode/Solar Optical Telescope in Ca II and Hα, the Interface Region Imaging Spectrograph, with slit jaw images and Mg II spectral data, and the Solar Dynamics Observatory’s Atmospheric Imaging Assembly. In the recent literature there has been a debate concerning whether these features, sometimes referred to as “tornadoes,” are rotating. Our data analysis provides no evidence for systematic rotation in the barbs. We do find line-of-sight motions in the barbs that vary with location and time. We also discuss observations of features moving along the barbs. These moving features are elongated parallel to the solar limb and tend to come in clusters of features moving along the same or similar paths in the plane of the sky during a period of 10 minutes to an hour, moving toward or away from the limb. The motion may have a component along the line of sight as well. The spectral data indicate that the features are Doppler shifted. We discuss possible explanations for these features.

SLoWPoKES-II: 100,000 WIDE BINARIES IDENTIFIED IN SDSS WITHOUT PROPER MOTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhital, Saurav; West, Andrew A.; Schluns, Kyle J.

2015-08-15

We present the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES)-II catalog of low-mass visual binaries identified from the Sloan Digital Sky Survey (SDSS) by matching photometric distances. The candidate pairs are vetted by comparing the stellar information. The candidate pairs are vetted by comparing the stellar density at their respective Galactic positions to Monte Carlo realizations of a simulated Milky Way. In this way, we are able to identify large numbers of bona fide wide binaries without the need for proper motions. Here, 105,537 visual binaries with angular separations of ∼1–20″ were identified, each with a probability ofmore » chance alignment of ≤5%. This is the largest catalog of bona fide wide binaries to date, and it contains a diversity of systems—in mass, mass ratios, binary separations, metallicity, and evolutionary states—that should facilitate follow-up studies to characterize the properties of M dwarfs and white dwarfs. There is a subtle but definitive suggestion of multiple populations in the physical separation distribution, supporting earlier findings. We suggest that wide binaries are composed of multiple populations, most likely representing different formation modes. There are 141 M7 or later wide binary candidates, representing a seven-fold increase over the number currently known. These binaries are too wide to have been formed via the ejection mechanism. Finally, we found that 6% of spectroscopically confirmed M dwarfs are not included in the SDSS STAR catalog; they are misclassified as extended sources due to the presence of a nearby or partially resolved companion. The SLoWPoKES-II catalog is publicly available to the entire community on the World Wide Web via the Filtergraph data visualization portal.« less

Proper horizontal photospheric flows in a filament channel

NASA Astrophysics Data System (ADS)

Schmieder, B.; Roudier, T.; Mein, N.; Mein, P.; Malherbe, J. M.; Chandra, R.

2014-04-01

Context. An extended filament in the central part of the active region NOAA 11106 crossed the central meridian on Sept. 17, 2010 in the southern hemisphere. It has been observed in Hα with the THEMIS telescope in the Canary Islands and in 304 Å with the EUV imager (AIA) onboard the Solar Dynamic Observatory (SDO). Counterstreaming along the Hα threads and bright moving blobs (jets) along the 304 Å filament channel were observed during 10 h before the filament erupted at 17:03 UT. Aims: The aim of the paper is to understand the coupling between magnetic field and convection in filament channels and relate the horizontal photospheric motions to the activity of the filament. Methods: An analysis of the proper photospheric motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track granules, as well as the large scale photospheric flows, was performed for three hours. Using corks, we derived the passive scalar points and produced a map of the cork distribution in the filament channel. Averaging the velocity vectors in the southern hemisphere in each latitude in steps of 3.5 arcsec, we defined a profile of the differential rotation. Results: Supergranules are clearly identified in the filament channel. Diverging flows inside the supergranules are similar in and out of the filament channel. Converging flows corresponding to the accumulation of corks are identified well around the Hα filament feet and at the edges of the EUV filament channel. At these convergence points, the horizontal photospheric velocity may reach 1 km s-1, but with a mean velocity of 0.35 km s-1. In some locations, horizontal flows crossing the channel are detected, indicating eventually large scale vorticity. Conclusions: The coupling between convection and magnetic field in the photosphere is relatively strong. The filament experienced the convection motions through its anchorage points with the photosphere, which are

Proper motions in the VVV Survey: Results for more than 15 million stars across NGC 6544

NASA Astrophysics Data System (ADS)

Contreras Ramos, R.; Zoccali, M.; Rojas, F.; Rojas-Arriagada, A.; Gárate, M.; Huijse, P.; Gran, F.; Soto, M.; Valcarce, A. A. R.; Estévez, P. A.; Minniti, D.

2017-12-01

Context. In the last six years, the VISTA Variable in the Vía Láctea (VVV) survey mapped 562 sq. deg. across the bulge and southern disk of the Galaxy. However, a detailed study of these regions, which includes 36 globular clusters (GCs) and thousands of open clusters is by no means an easy challenge. High differential reddening and severe crowding along the line of sight makes highly hamper to reliably distinguish stars belonging to different populations and/or systems. Aims: The aim of this study is to separate stars that likely belong to the Galactic GC NGC 6544 from its surrounding field by means of proper motion (PM) techniques. Methods: This work was based upon a new astrometric reduction method optimized for images of the VVV survey. Results: PSF-fitting photometry over the six years baseline of the survey allowed us to obtain a mean precision of 0.51 mas yr-1, in each PM coordinate, for stars with Ks< 15 mag. In the area studied here, cluster stars separate very well from field stars, down to the main sequence turnoff and below, allowing us to derive for the first time the absolute PM of NGC 6544. Isochrone fitting on the clean and differential reddening corrected cluster color magnitude diagram yields an age of 11-13 Gyr, and metallicity [Fe/H] =-1.5 dex, in agreement with previous studies restricted to the cluster core. We were able to derive the cluster orbit assuming an axisymmetric model of the Galaxy and conclude that NGC 6544 is likely a halo GC. We have not detected tidal tail signatures associated to the cluster, but a remarkable elongation in the galactic center direction has been found. The precision achieved in the PM determination also allows us to separate bulge stars from foreground disk stars, enabling the kinematical selection of bona fide bulge stars across the whole survey area. Conclusions: Kinematical techniques are a fundamental step toward disentangling different stellar populations that overlap in a studied field. Our results show

HELICAL MOTIONS OF FINE-STRUCTURE PROMINENCE THREADS OBSERVED BY HINODE AND IRIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okamoto, Takenori J.; Liu, Wei; Tsuneta, Saku, E-mail: joten.okamoto@nao.ac.jp

Fine-structure dynamics in solar prominences holds critical clues to understanding their physical nature of significant space-weather implications. We report evidence of rotational motions of horizontal helical threads in two active-region prominences observed by the Hinode and/or Interface Region Imaging Spectrograph satellites at high resolution. In the first event, we found transverse motions of brightening threads at speeds up to 55 km s{sup -1} seen in the plane of the sky. Such motions appeared as sinusoidal space–time trajectories with a typical period of ∼390 s, which is consistent with plane-of-sky projections of rotational motions. Phase delays at different locations suggest themore » propagation of twists along the threads at phase speeds of 90–270 km s{sup -1}. At least 15 episodes of such motions occurred in two days, none associated with an eruption. For these episodes, the plane-of-sky speed is linearly correlated with the vertical travel distance, suggestive of a constant angular speed. In the second event, we found Doppler velocities of 30–40 km s{sup -1} in opposite directions in the top and bottom portions of the prominence, comparable to the plane-of-sky speed. The moving threads have about twice broader line widths than stationary threads. These observations, when taken together, provide strong evidence for rotations of helical prominence threads, which were likely driven by unwinding twists triggered by magnetic reconnection between twisted prominence magnetic fields and ambient coronal fields.« less

Linear Extended State Observer-Based Motion Synchronization Control for Hybrid Actuation System of More Electric Aircraft.

PubMed

Wang, Xingjian; Liao, Rui; Shi, Cun; Wang, Shaoping

2017-10-25

Moving towards the more electric aircraft (MEA), a hybrid actuator configuration provides an opportunity to introduce electromechanical actuator (EMA) into primary flight control. In the hybrid actuation system (HAS), an electro-hydraulic servo actuator (EHSA) and an EMA operate on the same control surface. In order to solve force fighting problem in HAS, this paper proposes a novel linear extended state observer (LESO)-based motion synchronization control method. To cope with the problem of unavailability of the state signals required by the motion synchronization controller, LESO is designed for EHSA and EMA to observe the state variables. Based on the observed states of LESO, motion synchronization controllers could enable EHSA and EMA to simultaneously track the desired motion trajectories. Additionally, nonlinearities, uncertainties and unknown disturbances as well as the coupling term between EHSA and EMA can be estimated and compensated by using the extended state of the proposed LESO. Finally, comparative simulation results indicate that the proposed LESO-based motion synchronization controller could reduce significant force fighting between EHSA and EMA.

Linear Extended State Observer-Based Motion Synchronization Control for Hybrid Actuation System of More Electric Aircraft

PubMed Central

Liao, Rui; Shi, Cun; Wang, Shaoping

2017-01-01

Moving towards the more electric aircraft (MEA), a hybrid actuator configuration provides an opportunity to introduce electromechanical actuator (EMA) into primary flight control. In the hybrid actuation system (HAS), an electro-hydraulic servo actuator (EHSA) and an EMA operate on the same control surface. In order to solve force fighting problem in HAS, this paper proposes a novel linear extended state observer (LESO)-based motion synchronization control method. To cope with the problem of unavailability of the state signals required by the motion synchronization controller, LESO is designed for EHSA and EMA to observe the state variables. Based on the observed states of LESO, motion synchronization controllers could enable EHSA and EMA to simultaneously track the desired motion trajectories. Additionally, nonlinearities, uncertainties and unknown disturbances as well as the coupling term between EHSA and EMA can be estimated and compensated by using the extended state of the proposed LESO. Finally, comparative simulation results indicate that the proposed LESO-based motion synchronization controller could reduce significant force fighting between EHSA and EMA. PMID:29068392

Image deblurring by motion estimation for remote sensing

NASA Astrophysics Data System (ADS)

Chen, Yueting; Wu, Jiagu; Xu, Zhihai; Li, Qi; Feng, Huajun

2010-08-01

The imagery resolution of imaging systems for remote sensing is often limited by image degradation resulting from unwanted motion disturbances of the platform during image exposures. Since the form of the platform vibration can be arbitrary, the lack of priori knowledge about the motion function (the PSF) suggests blind restoration approaches. A deblurring method which combines motion estimation and image deconvolution both for area-array and TDI remote sensing has been proposed in this paper. The image motion estimation is accomplished by an auxiliary high-speed detector and a sub-pixel correlation algorithm. The PSF is then reconstructed from estimated image motion vectors. Eventually, the clear image can be recovered by the Richardson-Lucy (RL) iterative deconvolution algorithm from the blurred image of the prime camera with the constructed PSF. The image deconvolution for the area-array detector is direct. While for the TDICCD detector, an integral distortion compensation step and a row-by-row deconvolution scheme are applied. Theoretical analyses and experimental results show that, the performance of the proposed concept is convincing. Blurred and distorted images can be properly recovered not only for visual observation, but also with significant objective evaluation increment.

Validating Pseudo-dynamic Source Models against Observed Ground Motion Data at the SCEC Broadband Platform, Ver 16.5

NASA Astrophysics Data System (ADS)

Song, S. G.

2016-12-01

Simulation-based ground motion prediction approaches have several benefits over empirical ground motion prediction equations (GMPEs). For instance, full 3-component waveforms can be produced and site-specific hazard analysis is also possible. However, it is important to validate them against observed ground motion data to confirm their efficiency and validity before practical uses. There have been community efforts for these purposes, which are supported by the Broadband Platform (BBP) project at the Southern California Earthquake Center (SCEC). In the simulation-based ground motion prediction approaches, it is a critical element to prepare a possible range of scenario rupture models. I developed a pseudo-dynamic source model for Mw 6.5-7.0 by analyzing a number of dynamic rupture models, based on 1-point and 2-point statistics of earthquake source parameters (Song et al. 2014; Song 2016). In this study, the developed pseudo-dynamic source models were tested against observed ground motion data at the SCEC BBP, Ver 16.5. The validation was performed at two stages. At the first stage, simulated ground motions were validated against observed ground motion data for past events such as the 1992 Landers and 1994 Northridge, California, earthquakes. At the second stage, they were validated against the latest version of empirical GMPEs, i.e., NGA-West2. The validation results show that the simulated ground motions produce ground motion intensities compatible with observed ground motion data at both stages. The compatibility of the pseudo-dynamic source models with the omega-square spectral decay and the standard deviation of the simulated ground motion intensities are also discussed in the study

Broadband Ground Motion Observation and Simulation for the 2016 Kumamoto Earthquake

NASA Astrophysics Data System (ADS)

Miyake, H.; Chimoto, K.; Yamanaka, H.; Tsuno, S.; Korenaga, M.; Yamada, N.; Matsushima, T.; Miyakawa, K.

2016-12-01

During the 2016 Kumamoto earthquake, strong motion data were widely recorded by the permanent dense triggered strong motion network of K-NET/KiK-net and seismic intensity meters installed by local government and JMA. Seismic intensities close to the MMI 9-10 are recorded twice at the Mashiki town, and once at the Nishihara village and KiK-net Mashiki (KMMH16 ground surface). Near-fault records indicate extreme ground motion exceeding 400 cm/s in 5% pSv at a period of 1 s for the Mashiki town and 3-4 s for the Nishihara village. Fault parallel velocity components are larger between the Mashiki town and the Nishihara village, on the other hand, fault normal velocity components are larger inside the caldera of the Aso volcano. The former indicates rupture passed through along-strike stations, and the latter stations located at the forward rupture direction (e.g., Miyatake, 1999). In addition to the permanent observation, temporary continuous strong motion stations were installed just after the earthquake in the Kumamoto city, Mashiki town, Nishihara village, Minami-Aso village, and Aso town, (e.g., Chimoto et al., 2016; Tsuno et al., 2016; Yamanaka et al. 2016). This study performs to estimate strong motion generation areas for the 2016 Kumamoto earthquake sequence using the empirical Green's function method, then to simulate broadband ground motions for both the permanent and temporary strong motion stations. Currently the target period range is between 0.1 s to 5-10 s due to the signal-to-noise ratio of element earthquakes used for the empirical Green's functions. We also care fault dimension parameters N within 4 to 10 to avoid spectral sags and artificial periodicity. The simulated seismic intensities as well as fault normal and parallel velocity components will be discussed.

Chico High School Students' Astrometric Observations of the Visual Double Star STF 1657

NASA Astrophysics Data System (ADS)

Ahiligwo, Jonelle; Bergamini, Clara; Berglund, Kallan; Bhardwaj, Mohit; Chelson, Spud; Costa, Amanda; Epis, Ashley; Grant, Azure; Osteen, Courtney; Reiner, Skyla; Rose, Adam; Schmidt, Emily; Sears, Forest; Sullivan-Hames, Maddie; Johnson, Jolyon

2012-01-01

In the spring of 2011, Chico Senior High School students participated in an astronomy seminar at the Gateway Science Museum, University of California, Chico. The observers used a Celestron NexStar 6 SE telescope and a Celestron MicroGuide eyepiece to determine the separation and position angle of the visual double star STF 1657. Observations were made in approximately one hour on the evening of May 1, 2011. The observers determined that the separation of STF 1657 was 22.1" and the position angle was 273.4&°. Seminar members then used the spectral type, parallax, and proper motion vectors of the two stars to determine if they are a line-of-sight optical pair or physically bound by gravity. Due to large errors in the parallax and the proper motion vector for the secondary star, the results were inconclusive. Through this experience, the students learned the skills needed to observe, analyze, and report on double stars.

VLBI Phase-Referenced Observations on Southern Hemisphere HIPPARCOS Radio Start

NASA Technical Reports Server (NTRS)

Guirado, J. C.; Preston, R. A.; Jones, D. L.; Lestrade, J. F.; Reynolds, J. E.; Jauncey, D. L.; Tzioumis, A. K.; Ferris, R. H.; King, E. A.; Lovell, J. E. J.;

Mass motion in upper solar chromosphere detected from solar eclipse observation

NASA Astrophysics Data System (ADS)

Li, Zhi; Qu, Zhongquan; Yan, Xiaoli; Dun, Guangtao; Chang, Liang

2016-05-01

The eclipse-observed emission lines formed in the upper solar atmosphere can be used to diagnose the atmosphere dynamics which provides an insight to the energy balance of the outer atmosphere. In this paper, we analyze the spectra formed in the upper chromospheric region by a new instrument called Fiber Arrayed Solar Optic Telescope (FASOT) around the Gabon total solar eclipse on November 3, 2013. The double Gaussian fits of the observed profiles are adopted to show enhanced emission in line wings, while red-blue (RB) asymmetry analysis informs that the cool line (about 104 K) profiles can be decomposed into two components and the secondary component is revealed to have a relative velocity of about 16-45 km s^{-1}. The other profiles can be reproduced approximately with single Gaussian fits. From these fittings, it is found that the matter in the upper solar chromosphere is highly dynamic. The motion component along the line-of-sight has a pattern asymmetric about the local solar radius. Most materials undergo significant red shift motions while a little matter show blue shift. Despite the discrepancy of the motion in different lines, we find that the width and the Doppler shifts both are function of the wavelength. These results may help us to understand the complex mass cycle between chromosphere and corona.

Hubble imaging of V1331 Cygni: proper motion study of its circumstellar structures

NASA Astrophysics Data System (ADS)

Choudhary, A.; Stecklum, B.; Linz, Hendrik

2016-05-01

Aims: The young star V1331 Cyg received previous attention because it is surrounded by an optical, arc-like reflection nebula. V1331 Cyg is commonly considered to be a candidate for an object that has undergone an FU-Ori (FUOR) outbreak in the past. This in turn could lead to a time-varying appearance of the dusty arcs that may be revealed by multi-epoch imaging. In particular, a radial colour analysis of the dust arcs can then be attempted to check whether the radial grain size distribution was modified by a previous FUOR wind. Methods: Second-epoch imaging of V1331 Cyg was obtained by us in 2009 using the Hubble Space Telescope (HST). By comparing this to archival HST data from 2000, we studied the time evolution of the circumstellar nebulae. After a point spread function subtraction using model point spread functions, we used customised routines to perform a proper motion analysis. The nebula expansion was derived by deconvolving and correlating the two-epoch radial brightness profiles. Additional data from other facilities - TLS, UKIDSS, Spitzer, and Herschel - were also incorporated to improve our understanding of the star in terms of environment, viewing angle, bipolar outflow length, and the FUOR phenomenon. Results: The outer dust arc is found to be expanding at ≈14.8 ± 3.6 km s-1 on average. The expansion velocity for the inner ring is less consistent, between 0.8 km s-1 and 3.0 km s-1. The derived radial colour profiles do not indicate a spatial separation of the dust grain sizes. The Herschel 160 μm images show for the first time thermal emission from dust probably residing in the outer arc. By viewing V1331 Cyg almost pole-on, the length of the bipolar outflow exceeds previous estimates by far. Conclusions: The outer arc expansion timescale is consistent with the implantation time of the CO torus, which supports the hypothesis of an outburst that occurred a few thousand years ago. The azimuthal colour variation of the outer arc is probably due to

Extended state observer-based motion synchronisation control for hybrid actuation system of large civil aircraft

NASA Astrophysics Data System (ADS)

Wang, Xingjian; Shi, Cun; Wang, Shaoping

2017-07-01

Hybrid actuation system with dissimilar redundant actuators, which is composed of a hydraulic actuator (HA) and an electro-hydrostatic actuator (EHA), has been applied on modern civil aircraft to improve the reliability. However, the force fighting problem arises due to different dynamic performances between HA and EHA. This paper proposes an extended state observer (ESO)-based motion synchronisation control method. To cope with the problem of unavailability of the state signals, the well-designed ESO is utilised to observe the HA and EHA state variables which are unmeasured. In particular, the extended state of ESO can estimate the lumped effect of the unknown external disturbances acting on the control surface, the nonlinear dynamics, uncertainties, and the coupling term between HA and EHA. Based on the observed states of ESO, motion synchronisation controllers are presented to make HA and EHA to simultaneously track the desired motion trajectories, which are generated by a trajectory generator. Additionally, the unknown disturbances and the coupling terms can be compensated by using the extended state of the proposed ESO. Finally, comparative simulation results indicate that the proposed ESO-based motion synchronisation controller can achieve great force fighting reduction between HA and EHA.

Predicted Attenuation Relation and Observed Ground Motion of Gorkha Nepal Earthquake of 25 April 2015

NASA Astrophysics Data System (ADS)

Singh, R. P.; Ahmad, R.

2015-12-01

A comparison of recent observed ground motion parameters of recent Gorkha Nepal earthquake of 25 April 2015 (Mw 7.8) with the predicted ground motion parameters using exitsing attenuation relation of the Himalayan region will be presented. The recent earthquake took about 8000 lives and destroyed thousands of poor quality of buildings and the earthquake was felt by millions of people living in Nepal, China, India, Bangladesh, and Bhutan. The knowledge of ground parameters are very important in developing seismic code of seismic prone regions like Himalaya for better design of buildings. The ground parameters recorded in recent earthquake event and aftershocks are compared with attenuation relations for the Himalayan region, the predicted ground motion parameters show good correlation with the observed ground parameters. The results will be of great use to Civil engineers in updating existing building codes in the Himlayan and surrounding regions and also for the evaluation of seismic hazards. The results clearly show that the attenuation relation developed for the Himalayan region should be only used, other attenuation relations based on other regions fail to provide good estimate of observed ground motion parameters.

Low-Frequency Amplitudes Observed in a Set of the Strongest Recorded Ground Motions (Invited)

NASA Astrophysics Data System (ADS)

Anderson, J. G.; Koketsu, K.; Miyake, H.

2010-12-01

Anderson (2010) compiled a set of “exceptional” ground motion characterized by peak acceleration that exceeds 500 gal on at least one component or peak velocity that exceeds 50 cm/s on at least one component. With the addition of more recent data, there are now over 280 openly available records that meet these criteria. These data are examined to find to the empirical upper bound of observed pseudo-acceleration (PSA) response spectra and smoothed Fourier amplitude spectra. Statistics of amplitudes of PSA and of low-pass filtered acceleration and velocity have also been determined. Amplitudes recorded at the Kawaguchi-cho station (40 km) at 5-6 second period from the 1964 Niigata earthquake (Mw=8.3) are within ~20% of the current empirical limit of ground motions observed from all earthquakes in the data set including those from the near field. An even more impressive example is that amplitudes recorded at the SCT station (~300 km from the fault) with period of about 2 seconds, during the 1985 Michoacan, Mexico, earthquake (Mw=8.0), are about the same as the current empirical limit of ground motions observed from near field records. These examples support the idea that the hazard caused by long-period ground motions, amplified by basins and site conditions, is not sufficiently appreciated. Reference: Anderson, J. G. (2010), Bull. Seism. Soc. Am. 100, 1-36.

Estimation of Source and Attenuation Parameters from Ground Motion Observations for Induced Seismicity in Alberta

NASA Astrophysics Data System (ADS)

Novakovic, M.; Atkinson, G. M.

2015-12-01

We use a generalized inversion to solve for site response, regional source and attenuation parameters, in order to define a region-specific ground-motion prediction equation (GMPE) from ground motion observations in Alberta, following the method of Atkinson et al. (2015 BSSA). The database is compiled from over 200 small to moderate seismic events (M 1 to 4.2) recorded at ~50 regional stations (distances from 30 to 500 km), over the last few years; almost all of the events have been identified as being induced by oil and gas activity. We remove magnitude scaling and geometric spreading functions from observed ground motions and invert for stress parameter, regional attenuation and site amplification. Resolving these parameters allows for the derivation of a regionally-calibrated GMPE that can be used to accurately predict amplitudes across the region in real time, which is useful for ground-motion-based alerting systems and traffic light protocols. The derived GMPE has further applications for the evaluation of hazards from induced seismicity.

Categorization of compensatory motions in transradial myoelectric prosthesis users.

PubMed

Hussaini, Ali; Zinck, Arthur; Kyberd, Peter

2017-06-01

Prosthesis users perform various compensatory motions to accommodate for the loss of the hand and wrist as well as the reduced functionality of a prosthetic hand. Investigate different compensation strategies that are performed by prosthesis users. Comparative analysis. A total of 20 able-bodied subjects and 4 prosthesis users performed a set of bimanual activities. Movements of the trunk and head were recorded using a motion capture system and a digital video recorder. Clinical motion angles were calculated to assess the compensatory motions made by the prosthesis users. The video recording also assisted in visually identifying the compensations. Compensatory motions by the prosthesis users were evident in the tasks performed (slicing and stirring activities) as compared to the benchmark of able-bodied subjects. Compensations took the form of a measured increase in range of motion, an observed adoption of a new posture during task execution, and prepositioning of items in the workspace prior to initiating a given task. Compensatory motions were performed by prosthesis users during the selected tasks. These can be categorized into three different types of compensations. Clinical relevance Proper identification and classification of compensatory motions performed by prosthesis users into three distinct forms allows clinicians and researchers to accurately identify and quantify movement. It will assist in evaluating new prosthetic interventions by providing distinct terminology that is easily understood and can be shared between research institutions.

Simultaneous observations of ice motion, calving and seismicity on the Yahtse Glacier, Alaska. (Invited)

NASA Astrophysics Data System (ADS)

Larsen, C. F.; Bartholomaus, T. C.; O'Neel, S.; West, M. E.

2010-12-01

We observe ice motion, calving and seismicity simultaneously and with high-resolution on an advancing tidewater glacier in Icy Bay, Alaska. Icy Bay’s tidewater glaciers dominate regional glacier-generated seismicity in Alaska. Yahtse emanates from the St. Elias Range near the Bering-Bagley-Seward-Malaspina Icefield system, the most extensive glacier cover outside the polar regions. Rapid rates of change and fast flow (>16 m/d near the terminus) at Yahtse Glacier provide a direct analog to the disintegrating outlet systems in Greenland. Our field experiment co-locates GPS and seismometers on the surface of the glacier, with a greater network of bedrock seismometers surrounding the glacier. Time-lapse photogrammetry, fjord wave height sensors, and optical survey methods monitor iceberg calving and ice velocity near the terminus. This suite of geophysical instrumentation enables us to characterize glacier motion and geometry changes while concurrently listening for seismic energy release. We are performing a close examination of calving as a seismic source, and the associated mechanisms of energy transfer to seismic waves. Detailed observations of ice motion (GPS and optical surveying), glacier geometry and iceberg calving (direct observations and timelapse photogrammetry) have been made in concert with a passive seismic network. Combined, the observations form the basis of a rigorous analysis exploring the relationship between glacier-generated seismic events and motion, glacier-fiord interactions, calving and hydraulics. Our work is designed to demonstrate the applicability and utility of seismology to study the impact of climate forcing on calving glaciers.

Identification of Piecewise Linear Uniform Motion Blur

NASA Astrophysics Data System (ADS)

Patanukhom, Karn; Nishihara, Akinori

A motion blur identification scheme is proposed for nonlinear uniform motion blurs approximated by piecewise linear models which consist of more than one linear motion component. The proposed scheme includes three modules that are a motion direction estimator, a motion length estimator and a motion combination selector. In order to identify the motion directions, the proposed scheme is based on a trial restoration by using directional forward ramp motion blurs along different directions and an analysis of directional information via frequency domain by using a Radon transform. Autocorrelation functions of image derivatives along several directions are employed for estimation of the motion lengths. A proper motion combination is identified by analyzing local autocorrelation functions of non-flat component of trial restored results. Experimental examples of simulated and real world blurred images are given to demonstrate a promising performance of the proposed scheme.

Non-rigid Motion Correction in 3D Using Autofocusing with Localized Linear Translations

PubMed Central

Cheng, Joseph Y.; Alley, Marcus T.; Cunningham, Charles H.; Vasanawala, Shreyas S.; Pauly, John M.; Lustig, Michael

2012-01-01

MR scans are sensitive to motion effects due to the scan duration. To properly suppress artifacts from non-rigid body motion, complex models with elements such as translation, rotation, shear, and scaling have been incorporated into the reconstruction pipeline. However, these techniques are computationally intensive and difficult to implement for online reconstruction. On a sufficiently small spatial scale, the different types of motion can be well-approximated as simple linear translations. This formulation allows for a practical autofocusing algorithm that locally minimizes a given motion metric – more specifically, the proposed localized gradient-entropy metric. To reduce the vast search space for an optimal solution, possible motion paths are limited to the motion measured from multi-channel navigator data. The novel navigation strategy is based on the so-called “Butterfly” navigators which are modifications to the spin-warp sequence that provide intrinsic translational motion information with negligible overhead. With a 32-channel abdominal coil, sufficient number of motion measurements were found to approximate possible linear motion paths for every image voxel. The correction scheme was applied to free-breathing abdominal patient studies. In these scans, a reduction in artifacts from complex, non-rigid motion was observed. PMID:22307933

Chromosomal locus tracking with proper accounting of static and dynamic errors

PubMed Central

Backlund, Mikael P.; Joyner, Ryan; Moerner, W. E.

2015-01-01

The mean-squared displacement (MSD) and velocity autocorrelation (VAC) of tracked single particles or molecules are ubiquitous metrics for extracting parameters that describe the object’s motion, but they are both corrupted by experimental errors that hinder the quantitative extraction of underlying parameters. For the simple case of pure Brownian motion, the effects of localization error due to photon statistics (“static error”) and motion blur due to finite exposure time (“dynamic error”) on the MSD and VAC are already routinely treated. However, particles moving through complex environments such as cells, nuclei, or polymers often exhibit anomalous diffusion, for which the effects of these errors are less often sufficiently treated. We present data from tracked chromosomal loci in yeast that demonstrate the necessity of properly accounting for both static and dynamic error in the context of an anomalous diffusion that is consistent with a fractional Brownian motion (FBM). We compare these data to analytical forms of the expected values of the MSD and VAC for a general FBM in the presence of these errors. PMID:26172745

A Pan-STARRS1 Proper-Motion Survey for Young Brown Dwarfs in the Nearest Star-Forming Regions and a Reddening-Free Classification Method for Ultracool Dwarfs

NASA Astrophysics Data System (ADS)

Zhang, Zhoujian; Liu, Michael C.; Best, William M. J.; Magnier, Eugene; Aller, Kimberly

2018-01-01

Young brown dwarfs are of prime importance to investigate the universality of the initial mass function (IMF). Based on photometry and proper motions from the Pan-STARRS1 (PS1) 3π survey, we are conducting the widest and deepest brown dwarf survey in the nearby star-forming regions, Taurus–Auriga (Taurus) and Upper Scorpius (USco). Our work is the first to measure proper motions, a robust proxy of membership, for brown dwarf candidates in Taurus and USco over such a large area and long time baseline (≈ 15 year) with such high precision (≈ 4 mas yr-1). Since extinction complicates spectral classification, we have developed a new approach to quantitatively determine reddening-free spectral types, extinctions, and gravity classifications for mid-M to late-L ultracool dwarfs (≈ 100–5 MJup), using low-resolution near-infrared spectra. So far, our IRTF/SpeX spectroscopic follow-up has increased the substellar and planetary-mass census of Taurus by ≈ 50% and almost doubled the substellar census of USco, constituting the largest single increases of brown dwarfs and free-floating planets found in both regions to date. Most notably, our new discoveries reveal an older (> 10 Myr) low-mass population in Taurus, in accord with recent studies of the higher-mass stellar members. In addition, the mass function appears to differ between the younger and older Taurus populations, possibly due to incompleteness of the older stellar members or different star formation processes. Upon completion, our survey will establish the most complete substellar and planetary-mass census in both Taurus and USco associations, make a significant addition to the low-mass IMF in both regions, and deliver more comprehensive pictures of star formation histories.

Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. IV. Kinematic Profiles and Average Masses of Blue Straggler Stars

NASA Astrophysics Data System (ADS)

Baldwin, A. T.; Watkins, L. L.; van der Marel, R. P.; Bianchini, P.; Bellini, A.; Anderson, J.

2016-08-01

We make use of the Hubble Space Telescope proper-motion catalogs derived by Bellini et al. to produce the first radial velocity dispersion profiles σ (R) for blue straggler stars (BSSs) in Galactic globular clusters (GCs), as well as the first dynamical estimates for the average mass of the entire BSS population. We show that BSSs typically have lower velocity dispersions than stars with mass equal to the main-sequence turnoff mass, as one would expect for a more massive population of stars. Since GCs are expected to experience some degree of energy equipartition, we use the relation σ \\propto {M}-η , where η is related to the degree of energy equipartition, along with our velocity dispersion profiles to estimate BSS masses. We estimate η as a function of cluster relaxation from recent Monte Carlo cluster simulations by Bianchini et al. and then derive an average mass ratio {M}{BSS}/{M}{MSTO}=1.50+/- 0.14 and an average mass {M}{BSS}=1.22+/- 0.12 M ⊙ from 598 BSSs across 19 GCs. The final error bars include any systematic errors that are random between different clusters, but not any potential biases inherent to our methodology. Our results are in good agreement with the average mass of {M}{BSS}=1.22+/- 0.06 M ⊙ for the 35 BSSs in Galactic GCs in the literature with properties that have allowed individual mass determination. Based on proprietary and archival observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

MOA Data Reveal a New Mass, Distance, and Relative Proper Motion for Planetary System OGLE-2015-BLG-0954L

NASA Astrophysics Data System (ADS)

Bennett, D. P.; Bond, I. A.; Abe, F.; Asakura, Y.; Barry, R.; Bhattacharya, A.; Donachie, M.; Evans, P.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Ranc, C.; Rattenbury, N. J.; Saito, To.; Sharan, A.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Yamada, T.; Yamada, T.; Yonehara, A.; MOA Collaboration

2017-08-01

We present the MOA Collaboration light-curve data for the planetary microlensing event OGLE-2015-BLG-0954, which was previously announced in a paper by the KMTNet and OGLE Collaborations. The MOA data cover the caustic exit, which was not covered by the KMTNet or Optical Gravitational Lensing Experiment (OGLE) data, and they provide a more reliable measurement of the finite source effect. The MOA data also provide a new source color measurement that reveals a lens-source relative proper motion of μ rel = 11.8 ± 0.8 mas yr-1, which compares to the value of μ rel = 18.4 ± 1.7 mas yr-1 reported in the KMTNet-OGLE paper. This new MOA value for μ rel has an a priori probability that is a factor of ≳100 times larger than the previous value, and it does not require a lens system distance of D L < 1 kpc. Based on the corrected source color, we find that the lens system consists of a planet of mass {3.4}-1.6+3.7 {M}{Jup} orbiting a {0.30}-0.14+0.34 {M}⊙ star at an orbital separation of {2.1}-1.0+2.2 {au} and a distance of {1.2}-0.5+1.1 {kpc}.

Observation of motion of colloidal particles undergoing flowing Brownian motion using self-mixing laser velocimetry with a thin-slice solid-state laser.

PubMed

Sudo, S; Ohtomo, T; Otsuka, K

2015-08-01

We achieved a highly sensitive method for observing the motion of colloidal particles in a flowing suspension using a self-mixing laser Doppler velocimeter (LDV) comprising a laser-diode-pumped thin-slice solid-state laser and a simple photodiode. We describe the measurement method and the optical system of the self-mixing LDV for real-time measurements of the motion of colloidal particles. For a condensed solution, when the light scattered from the particles is reinjected into the solid-state laser, the laser output is modulated in intensity by the reinjected laser light. Thus, we can capture the motion of colloidal particles from the spectrum of the modulated laser output. For a diluted solution, when the relaxation oscillation frequency coincides with the Doppler shift frequency, f_d, which is related to the average velocity of the particles, the spectrum reflecting the motion of the colloidal particles is enhanced by the resonant excitation of relaxation oscillations. Then, the spectral peak reflecting the motion of colloidal particles appears at 2×f_d. The spectrum reflecting the motion of colloidal particles in a flowing diluted solution can be measured with high sensitivity, owing to the enhancement of the spectrum by the thin-slice solid-state laser.

Effects of walker gender and observer gender on biological motion walking direction discrimination.

PubMed

Yang, Xiaoying; Cai, Peng; Jiang, Yi

2014-09-01

The ability to recognize the movements of other biological entities, such as whether a person is walking toward you, is essential for survival and social interaction. Previous studies have shown that the visual system is particularly sensitive to approaching biological motion. In this study, we examined whether the gender of walkers and observers influenced the walking direction discrimination of approaching point-light walkers in fine granularity. The observers were presented a walker who walked in different directions and were asked to quickly judge the walking direction (left or right). The results showed that the observers demonstrated worse direction discrimination when the walker was depicted as male than when the walker was depicted as female, probably because the observers tended to perceive the male walkers as walking straight ahead. Intriguingly, male observers performed better than female observers at judging the walking directions of female walkers but not those of male walkers, a result indicating perceptual advantage with evolutionary significance. These findings provide strong evidence that the gender of walkers and observers modulates biological motion perception and that an adaptive perceptual mechanism exists in the visual system to facilitate the survival of social organisms. © 2014 The Institute of Psychology, Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Investigation on the real-time prediction of ground motions using seismic records observed in deep boreholes

NASA Astrophysics Data System (ADS)

Miyakoshi, H.; Tsuno, S.

2013-12-01

The present method of the EEW system installed in the railway field of Japan predicts seismic ground motions based on the estimated earthquake information about epicentral distances and magnitudes using initial P-waves observed on the surface. In the case of local earthquakes beneath the Tokyo Metropolitan Area, however, a method to directly predict seismic ground motions using P-waves observed in deep boreholes could issue EEWs more simply and surely. Besides, a method to predict seismic ground motions, using S-waves observed in deep boreholes and S-wave velocity structures beneath seismic stations, could show planar distributions of ground motions for train operation control areas in the aftermath of earthquakes. This information is available to decide areas in which the emergency inspection of railway structures should be performed. To develop those two methods, we investigated relationships between peak amplitudes on the surface and those in deep boreholes, using seismic records of KiK-net stations in the Kanto Basin. In this study, we used earthquake accelerograms observed in boreholes whose depths are deeper than the top face of Pre-Neogene basement and those on the surface at 12 seismic stations of KiK-net. We selected 243 local earthquakes whose epicenters are located around the Kanto Region. Those JMA magnitudes are in the range from 4.5 to 7.0. We picked the on-set of P-waves and S-waves using a vertical component and two horizontal components, respectively. Peak amplitudes of P-waves and S-waves were obtained using vertical components and vector sums of two horizontal components, respectively. We estimated parameters which represent site amplification factors beneath seismic stations, using peak amplitudes of S-waves observed in the deep borehole and those on the surface, to minimize the residuals between calculations by the theoretical equation and observations. Correlation coefficients between calculations and observations are high values in the range

Horizontal supergranule-scale motions inferred from TRACE ultraviolet observations of the chromosphere

NASA Astrophysics Data System (ADS)

Tian, H.; Potts, H. E.; Marsch, E.; Attie, R.; He, J.-S.

2010-09-01

Aims: We study horizontal supergranule-scale motions revealed by TRACE observation of the chromospheric emission, and investigate the coupling between the chromosphere and the underlying photosphere. Methods: A highly efficient feature-tracking technique called balltracking has been applied for the first time to the image sequences obtained by TRACE (transition region and coronal explorer) in the passband of white light and the three ultraviolet passbands centered at 1700 Å, 1600 Å, and 1550 Å. The resulting velocity fields have been spatially smoothed and temporally averaged in order to reveal horizontal supergranule-scale motions that may exist at the emission heights of these passbands. Results: We find indeed a high correlation between the horizontal velocities derived in the white-light and ultraviolet passbands. The horizontal velocities derived from the chromospheric and photospheric emission are comparable in magnitude. Conclusions: The horizontal motions derived in the UV passbands might indicate the existence of a supergranule-scale magneto-convection in the chromosphere, which may shed new light on the study of mass and energy supply to the corona and solar wind at the height of the chromosphere. However, it is also possible that the apparent motions reflect the chromospheric brightness evolution as produced by acoustic shocks which might be modulated by the photospheric granular motions in their excitation process, or advected partly by the supergranule-scale flow towards the network while propagating upward from the photosphere. To reach a firm conclusion, it is necessary to investigate the role of granular motions in the excitation of shocks through numerical modeling, and future high-cadence chromospheric magnetograms must be scrutinized.

The equation of motion for a radiating charged particle without self-interaction term

NASA Astrophysics Data System (ADS)

Herrera, L.

1990-03-01

The motion of a radiating charged particle is studied from the point of view of relativistic classical mechanics. Thus, the resulting equation of motion emerges from equating the total rate of change of momentum to the external force, without the introduction of a “self-force” term. Doing so, one is forced to abandon either one, or both, of the following restrictions: (a) the external force is non-dissipative, (b) the proper mass of the particle is constant. By abandoning (a) we obtain the Mo and Papas equation of motion, whereas allowing variations in the proper mass one is led, uniquely, to the Bonnor equation. A new equation of motion is proposed by abandoning both (a) and (b).

Observations of infragravity motions for reef fringed islands and atolls

NASA Astrophysics Data System (ADS)

Becker, J. M.; Merrifield, M. A.; Ford, M.

2012-12-01

The frequency of flooding events that affect low lying islands and atolls in the Pacific is expected to increase under current sea level rise projections. Infragravity (IG) motions, with periods ranging from approximately 25 to 400 seconds, are an important component of wave driven flooding events for reef fringed islands and atolls. The IG variability during wave events is analyzed and interpreted dynamically from pressure and current observations at four cross-reef transects in the North Pacific Ocean that include sites in the Republic of the Marshall Islands and Guam. The IG motions are shown to depend upon the spectral properties of the incident wave forcing and reef flat characteristics that include reef flat length (ranging from 100m to 450m at the four sites) and total water level due to setup and tides. A small inundation event at one of the sites is shown to occur due to large shoreline infragravity energy.

Estimation of current plate motions in Papua New Guinea from Global Positioning System observations

NASA Astrophysics Data System (ADS)

Tregoning, Paul; Lambeck, Kurt; Stolz, Art; Morgan, Peter; McClusky, Simon C.; van der Beek, Peter; McQueen, Herbert; Jackson, Russell J.; Little, Rodney P.; Laing, Alex; Murphy, Brian

1998-06-01

Plate tectonic motions have been estimated in Papua New Guinea from a 20 station network of Global Positioning System sites that has been observed over five campaigns from 1990 to 1996. The present velocities of the sites are consistent with geological models in which the South Bismarck, Woodlark, and Solomon Sea Plates form the principal tectonic elements between the Pacific and Australian Plates in this region. Active spreading is observed on the Woodlark Basin Spreading Centre but at a rate that is about half the rate determined from magnetic reversals. The other major motions observed are subduction on the New Britain Trench, seafloor spreading across the Bismarck Sea Seismic Lineation, convergence across the Ramu-Markham Fault and left-lateral strike slip across the Papuan Peninsula. These motions are consistent with a 8.2° Myr-1 clockwise rotation of the South Bismarck Plate about a pole in the Huon Gulf and a rotation of the Woodlark Plate away from the Australian Plate. Second order deformation may also be occurring; in particular, Manus Island and northern New Ireland may be moving northward relative to the Pacific Plate at ˜5-8 mm yr-1 (significant at the 95% but not at the 99% confidence level) which may suggest the existence of a North Bismarck Plate.

Boltzmann babies in the proper time measure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bousso, Raphael; Freivogel, Ben; Yang, I-S.

2008-05-15

After commenting briefly on the role of the typicality assumption in science, we advocate a phenomenological approach to the cosmological measure problem. Like any other theory, a measure should be simple, general, well defined, and consistent with observation. This allows us to proceed by elimination. As an example, we consider the proper time cutoff on a geodesic congruence. It predicts that typical observers are quantum fluctuations in the early universe, or Boltzmann babies. We sharpen this well-known youngness problem by taking into account the expansion and open spatial geometry of pocket universes. Moreover, we relate the youngness problem directly tomore » the probability distribution for observables, such as the temperature of the cosmic background radiation. We consider a number of modifications of the proper time measure, but find none that would make it compatible with observation.« less

Boltzmann babies in the proper time measure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bousso, Raphael; Bousso, Raphael; Freivogel, Ben

After commenting briefly on the role of the typicality assumption in science, we advocate a phenomenological approach to the cosmological measure problem. Like any other theory, a measure should be simple, general, well defined, and consistent with observation. This allows us to proceed by elimination. As an example, we consider the proper time cutoff on a geodesic congruence. It predicts that typical observers are quantum fluctuations in the early universe, or Boltzmann babies. We sharpen this well-known youngness problem by taking into account the expansion and open spatial geometry of pocket universes. Moreover, we relate the youngness problem directly tomore » the probability distribution for observables, such as the temperature of the cosmic background radiation. We consider a number of modifications of the proper time measure, but find none that would make it compatible with observation.« less

Crustal block motion model and interplate coupling along Ecuador-Colombia trench based on GNSS observation network

NASA Astrophysics Data System (ADS)

Ito, T.; Mora-Páez, H.; Peláez-Gaviria, J. R.; Kimura, H.; Sagiya, T.

2017-12-01

IntroductionEcuador-Colombia trench is located at the boundary between South-America plate, Nazca Plate and Caribrian plate. This region is very complexes such as subducting Caribrian plate and Nazca plate, and collision between Panama and northern part of the Andes mountains. The previous large earthquakes occurred along the subducting boundary of Nazca plate, such as 1906 (M8.8) and 1979 (M8.2). And also, earthquakes occurred inland, too. So, it is important to evaluate earthquake potentials for preparing huge damage due to large earthquake in near future. GNSS observation In the last decade, the GNSS observation was established in Columbia. The GNSS observation is called by GEORED, which is operated by servicing Geologico Colomiano. The purpose of GEORED is research of crustal deformation. The number of GNSS site of GEORED is consist of 60 continuous GNSS observation site at 2017 (Mora et al., 2017). The sampling interval of almost GNSS site is 30 seconds. These GNSS data were processed by PPP processing using GIPSY-OASYS II software. GEORED can obtain the detailed crustal deformation map in whole Colombia. In addition, we use 100 GNSS data at Ecuador-Peru region (Nocquet et al. 2014). Method We developed a crustal block movements model based on crustal deformation derived from GNSS observation. Our model considers to the block motion with pole location and angular velocity and the interplate coupling between each block boundaries, including subduction between the South-American plate and the Nazca plate. And also, our approach of estimation of crustal block motion and coefficient of interplate coupling are based on MCMC method. The estimated each parameter is obtained probably density function (PDF). Result We tested 11 crustal block models based on geological data, such as active fault trace at surface. The optimal number of crustal blocks is 11 for based on geological and geodetic data using AIC. We use optimal block motion model. And also, we estimate

Application of data assimilation methods for analysis and integration of observed and modeled Arctic Sea ice motions

NASA Astrophysics Data System (ADS)

Meier, Walter Neil

This thesis demonstrates the applicability of data assimilation methods to improve observed and modeled ice motion fields and to demonstrate the effects of assimilated motion on Arctic processes important to the global climate and of practical concern to human activities. Ice motions derived from 85 GHz and 37 GHz SSM/I imagery and estimated from two-dimensional dynamic-thermodynamic sea ice models are compared to buoy observations. Mean error, error standard deviation, and correlation with buoys are computed for the model domain. SSM/I motions generally have a lower bias, but higher error standard deviations and lower correlation with buoys than model motions. There are notable variations in the statistics depending on the region of the Arctic, season, and ice characteristics. Assimilation methods are investigated and blending and optimal interpolation strategies are implemented. Blending assimilation improves error statistics slightly, but the effect of the assimilation is reduced due to noise in the SSM/I motions and is thus not an effective method to improve ice motion estimates. However, optimal interpolation assimilation reduces motion errors by 25--30% over modeled motions and 40--45% over SSM/I motions. Optimal interpolation assimilation is beneficial in all regions, seasons and ice conditions, and is particularly effective in regimes where modeled and SSM/I errors are high. Assimilation alters annual average motion fields. Modeled ice products of ice thickness, ice divergence, Fram Strait ice volume export, transport across the Arctic and interannual basin averages are also influenced by assimilated motions. Assimilation improves estimates of pollutant transport and corrects synoptic-scale errors in the motion fields caused by incorrect forcings or errors in model physics. The portability of the optimal interpolation assimilation method is demonstrated by implementing the strategy in an ice thickness distribution (ITD) model. This research presents an

Is the Milky Way still breathing? RAVE-Gaia streaming motions

NASA Astrophysics Data System (ADS)

Carrillo, I.; Minchev, I.; Kordopatis, G.; Steinmetz, M.; Binney, J.; Anders, F.; Bienaymé, O.; Bland-Hawthorn, J.; Famaey, B.; Freeman, K. C.; Gilmore, G.; Gibson, B. K.; Grebel, E. K.; Helmi, A.; Just, A.; Kunder, A.; McMillan, P.; Monari, G.; Munari, U.; Navarro, J.; Parker, Q. A.; Reid, W.; Seabroke, G.; Sharma, S.; Siebert, A.; Watson, F.; Wojno, J.; Wyse, R. F. G.; Zwitter, T.

2018-04-01

We use data from the Radial Velocity Experiment (RAVE) and the Tycho-Gaia astrometric solution (TGAS) catalogue to compute the velocity fields yielded by the radial (VR), azimuthal (Vϕ),and vertical (Vz) components of associated Galactocentric velocity. We search in particular for variation in all three velocity components with distance above and below the disc mid-plane, as well as how each component of Vz (line-of-sight and tangential velocity projections) modifies the obtained vertical structure. To study the dependence of velocity on proper motion and distance, we use two main samples: a RAVE sample including proper motions from the Tycho-2, PPMXL, and UCAC4 catalogues, and a RAVE-TGAS sample with inferred distances and proper motions from the TGAS and UCAC5 catalogues. In both samples, we identify asymmetries in VR and Vz. Below the plane, we find the largest radial gradient to be ∂VR/∂R = -7.01 ± 0.61 km s-1 kpc-1, in agreement with recent studies. Above the plane, we find a similar gradient with ∂VR/∂R = -9.42 ± 1.77 km s-1 kpc-1. By comparing our results with previous studies, we find that the structure in Vz is strongly dependent on the adopted proper motions. Using the Galaxia Milky Way model, we demonstrate that distance uncertainties can create artificial wave-like patterns. In contrast to previous suggestions of a breathing mode seen in RAVE data, our results support a combination of bending and breathing modes, likely generated by a combination of external or internal and external mechanisms.

Strong motions observed by K-NET and KiK-net during the 2016 Kumamoto earthquake sequence

NASA Astrophysics Data System (ADS)

Suzuki, Wataru; Aoi, Shin; Kunugi, Takashi; Kubo, Hisahiko; Morikawa, Nobuyuki; Nakamura, Hiromitsu; Kimura, Takeshi; Fujiwara, Hiroyuki

2017-01-01

The nationwide strong-motion seismograph network of K-NET and KiK-net in Japan successfully recorded the strong ground motions of the 2016 Kumamoto earthquake sequence, which show the several notable characteristics. For the first large earthquake with a JMA magnitude of 6.5 (21:26, April 14, 2016, JST), the large strong motions are concentrated near the epicenter and the strong-motion attenuations are well predicted by the empirical relation for crustal earthquakes with a moment magnitude of 6.1. For the largest earthquake of the sequence with a JMA magnitude of 7.3 (01:25, April 16, 2016, JST), the large peak ground accelerations and velocities extend from the epicentral area to the northeast direction. The attenuation feature of peak ground accelerations generally follows the empirical relation, whereas that for velocities deviates from the empirical relation for stations with the epicentral distance of greater than 200 km, which can be attributed to the large Love wave having a dominant period around 10 s. The large accelerations were observed at stations even in Oita region, more than 70 km northeast from the epicenter. They are attributed to the local induced earthquake in Oita region, whose moment magnitude is estimated to be 5.5 by matching the amplitudes of the corresponding phases with the empirical attenuation relation. The real-time strong-motion observation has a potential for contributing to the mitigation of the ongoing earthquake disasters. We test a methodology to forecast the regions to be exposed to the large shaking in real time, which has been developed based on the fact that the neighboring stations are already shaken, for the largest event of the Kumamoto earthquakes, and demonstrate that it is simple but effective to quickly make warning. We also shows that the interpolation of the strong motions in real time is feasible, which will be utilized for the real-time forecast of ground motions based on the observed shakings.[Figure not available

An Improved Perturb and Observe Algorithm for Photovoltaic Motion Carriers

NASA Astrophysics Data System (ADS)

Peng, Lele; Xu, Wei; Li, Liming; Zheng, Shubin

2018-03-01

An improved perturbation and observation algorithm for photovoltaic motion carriers is proposed in this paper. The model of the proposed algorithm is given by using Lambert W function and tangent error method. Moreover, by using matlab and experiment of photovoltaic system, the tracking performance of the proposed algorithm is tested. And the results demonstrate that the improved algorithm has fast tracking speed and high efficiency. Furthermore, the energy conversion efficiency by the improved method has increased by nearly 8.2%.

Holding or Breaking with Ptolemy's Generalization: Considerations about the Motion of the Planetary Apsidal Lines in Medieval Islamic Astronomy.

PubMed

Mozaffari, S Mohammad

2017-03-01

Argument In the Almagest, Ptolemy finds that the apogee of Mercury moves progressively at a speed equal to his value for the rate of precession, namely one degree per century, in the tropical reference system of the ecliptic coordinates. He generalizes this to the other planets, so that the motions of the apogees of all five planets are assumed to be equal, while the solar apsidal line is taken to be fixed. In medieval Islamic astronomy, one change in this general proposition took place because of the discovery of the motion of the solar apogee in the ninth century, which gave rise to lengthy discussions on the speed of its motion. Initially Bīrūnī and later Ibn al-Zarqālluh assigned a proper motion to it, although at different rates. Nevertheless, appealing to the Ptolemaic generalization and interpreting it as a methodological axiom, the dominant idea became to extend it in order to include the motion of the solar apogee as well. Another change occurred after correctly making a distinction between the motion of the apogees and the rate of precession. Some Western Islamic astronomers generalized Ibn al-Zarqālluh's proper motion of the solar apogee to the apogees of the planets. Analogously, Ibn al-Shāṭir maintained that the motion of the apogees is faster than precession. Nevertheless, the Ptolemaic generalization in the case of the equality of the motions of the apogees remained untouchable, despite the notable development of planetary astronomy, in both theoretical and observational aspects, in the late Islamic period.

Experimental investigation of shaping disturbance observer design for motion control of precision mechatronic stages with resonances

NASA Astrophysics Data System (ADS)

Yang, Jin; Hu, Chuxiong; Zhu, Yu; Wang, Ze; Zhang, Ming

2017-08-01

In this paper, shaping disturbance observer (SDOB) is investigated for precision mechatronic stages with middle-frequency zero/pole type resonance to achieve good motion control performance in practical manufacturing situations. Compared with traditional standard disturbance observer (DOB), in SDOB a pole-zero cancellation based shaping filter is cascaded to the mechatronic stage plant to meet the challenge of motion control performance deterioration caused by actual resonance. Noting that pole-zero cancellation is inevitably imperfect and the controller may even consequently become unstable in practice, frequency domain stability analysis is conducted to find out how each parameter of the shaping filter affects the control stability. Moreover, the robust design criterion of the shaping filter, and the design procedure of SDOB, are both proposed to guide the actual design and facilitate practical implementation. The SDOB with the proposed design criterion is applied to a linear motor driven stage and a voice motor driven stage, respectively. Experimental results consistently validate the effectiveness nature of the proposed SDOB scheme in practical mechatronics motion applications. The proposed SDOB design actually could be an effective unit in the controller design for motion stages of mechanical manufacture equipments.

12 CFR 1081.212 - Dispositive motions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... as to which official notice may be taken, and any other evidentiary materials properly submitted in... stated therein, and must be signed under oath and penalty of perjury. (e) Page limitations for... motion (exclusive of any declarations, affidavits, or attachments) shall not exceed 35 pages in length...

12 CFR 1081.212 - Dispositive motions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... as to which official notice may be taken, and any other evidentiary materials properly submitted in... stated therein, and must be signed under oath and penalty of perjury. (e) Page limitations for... motion (exclusive of any declarations, affidavits, or attachments) shall not exceed 35 pages in length...

12 CFR 1081.212 - Dispositive motions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... as to which official notice may be taken, and any other evidentiary materials properly submitted in... stated therein, and must be signed under oath and penalty of perjury. (e) Page limitations for... motion (exclusive of any declarations, affidavits, or attachments) shall not exceed 35 pages in length...

Learning characteristics of a space-time neural network as a tether skiprope observer

NASA Technical Reports Server (NTRS)

Lea, Robert N.; Villarreal, James A.; Jani, Yashvant; Copeland, Charles

1992-01-01

The Software Technology Laboratory at JSC is testing a Space Time Neural Network (STNN) for observing tether oscillations present during retrieval of a tethered satellite. Proper identification of tether oscillations, known as 'skiprope' motion, is vital to safe retrieval of the tethered satellite. Our studies indicate that STNN has certain learning characteristics that must be understood properly to utilize this type of neural network for the tethered satellite problem. We present our findings on the learning characteristics including a learning rate versus momentum performance table.

Observability/Identifiability of Rigid Motion under Perspective Projection

DTIC Science & Technology

1994-03-08

Faugeras and S. Maybank . Motion from point mathces: multiplicity of solutions. Int. J, of Computer Vision, 1990. [16] D.B. Gennery. Tracking known...sequences. Int. 9. of computer vision, 1989. [37] S. Maybank . Theory of reconstruction from image motion. Springer Verlag, 1992. [38] Andrea 6...defined in section 5; in this appendix we show a simple characterization which is due to Faugeras and Maybank [15, 371. Theorem B.l . Let Q = UCVT

Facial motion parameter estimation and error criteria in model-based image coding

NASA Astrophysics Data System (ADS)

Liu, Yunhai; Yu, Lu; Yao, Qingdong

2000-04-01

Model-based image coding has been given extensive attention due to its high subject image quality and low bit-rates. But the estimation of object motion parameter is still a difficult problem, and there is not a proper error criteria for the quality assessment that are consistent with visual properties. This paper presents an algorithm of the facial motion parameter estimation based on feature point correspondence and gives the motion parameter error criteria. The facial motion model comprises of three parts. The first part is the global 3-D rigid motion of the head, the second part is non-rigid translation motion in jaw area, and the third part consists of local non-rigid expression motion in eyes and mouth areas. The feature points are automatically selected by a function of edges, brightness and end-node outside the blocks of eyes and mouth. The numbers of feature point are adjusted adaptively. The jaw translation motion is tracked by the changes of the feature point position of jaw. The areas of non-rigid expression motion can be rebuilt by using block-pasting method. The estimation approach of motion parameter error based on the quality of reconstructed image is suggested, and area error function and the error function of contour transition-turn rate are used to be quality criteria. The criteria reflect the image geometric distortion caused by the error of estimated motion parameters properly.

Observations of the freeze/thaw performance of lithium fluoride by motion picture photography

NASA Technical Reports Server (NTRS)

Jaworske, D. A.; Perry, W. D.

1991-01-01

To gain direct observation of the molten salt phase change, a novel containerless technique was developed where the high surface tension of lithium fluoride was used to suspend a bead of the molten salt inside a specially designed wire cage. By varying the current passing through the wire, the cage also served as a variable heat source. In this way, the freeze/thaw performance of the lithium fluoride could be photographed by motion picture photography without the influence of container walls. The motion picture photography of the lithium fluoride sample revealed several zones during the phase change, a solid zone and a liquid zone, as expected, and a slush zone that was predicted by thermal analysis modeling.

Desktop Parallax and Proper Motion: A Laboratory Exercise on Astrometry of Asteroids from Project CLEA

NASA Astrophysics Data System (ADS)

Marschall, L. A.; Snyder, G. A.; Good, R. F.; Hayden, M. B.; Cooper, P. R.

1998-12-01

Students in introductory and advanced astronomy classes can now experience the process of discovering asteroids, can measure proper motions, and can actually see the parallax of real astronomical objects on the screen, using a new set of computer-based exercises from Project CLEA. The heart of the exercise is a sophisticated astrometry program "Astrometry of Asteroids", which is a restricted version of CLEA's research software "Tools for Astrometry" described elsewhere at this meeting. The program, as used in the teaching lab, allows students to read and display digital images, co-align pairs of images using designated reference stars, blink and identify moving objects on the pairs, compare images with charts produced from the HST Guide Star Catalog (GSC), and fit equatorial coordinates to the images using designated reference stars from the GSC. Complete technical manuals for the exercise are provided for the use of the instructor, and a set of digital images, in FITS format, is included for the exercise. A student manual is provided for an exercise in which students go through the step-by-step process of determining the tangential velocity of an asteroid. Students first examine a series of images of a near-earth asteroid taken over several hours, blinking pairs to identify the moving object. They next measure the equatorial coordinates on a half-dozen images, and from this calculate an angular velocity of the object. Finally, using a pair of images of the asteroid taken simultaneously at the National Undergraduate Research Observatory (NURO) and at Colgate University, they measure the parallax of the asteroid, and thus its distance, which enables them to convert the angular velocity into a tangential velocity. An optional set of 10 pairs of images is provided, some of which contain asteroids, so that students can try to "find the asteroid" for themselves. The software is extremely flexible, and though materials are provided for a self-contained exercise, teachers

Effect of observed micropolar motions on wave propagation in deep Earth minerals

NASA Astrophysics Data System (ADS)

Abreu, Rafael; Thomas, Christine; Durand, Stephanie

2018-03-01

We provide a method to compute the Cosserat couple modulus for a bridgmanite (MgSiO3 silicate perovskite) solid from frequency gaps observed in Raman experiments. To this aim, we apply micropolar theory which is a generalization of the classical linear elastic theory, where each particle has an intrinsic rotational degree of freedom, called micro-rotation and/or spin, and which depends on the so-called Cosserat couple modulus μc that characterizes the micropolar medium. We investigate both wave propagation and dispersion. The wave propagation simulations in both potassium nitrate (KNO3) and bridgmanite crystal leads to a faster elastic wave propagation as well as to an independent rotational field of motion, called optic mode, which is smaller in amplitude compared to the conventional rotational field. The dispersion analysis predicts that the optic mode only appears above a cutoff frequency, ωr , which has been observed in Raman experiments done at high pressures and temperatures on bridgmanite crystal. The comparison of the cutoff frequency observed in experiments and the micropolar theory enables us to compute for the first time the temperature and pressure dependency of the Cosserat couple modulus μc of bridgmanite. This study thus shows that the micropolar theory can explain particle motions observed in laboratory experiments that were before neglected and that can now be used to constrain the micropolar elastic constants of Earth's mantle like material. This pioneer work aims at encouraging the use of micropolar theory in future works on deep Earth's mantle material by providing Cosserat couple modulus that were not available before.

Helicopter Flight Simulation Motion Platform Requirements

NASA Technical Reports Server (NTRS)

Schroeder, Jeffery Allyn

1999-01-01

To determine motion fidelity requirements, a series of piloted simulations was performed. Several key results were found. First, lateral and vertical translational platform cues had significant effects on fidelity. Their presence improved performance and reduced pilot workload. Second, yaw and roll rotational platform cues were not as important as the translational platform cues. In particular, the yaw rotational motion platform cue did not appear at all useful in improving performance or reducing workload. Third, when the lateral translational platform cue was combined with visual yaw rotational cues, pilots believed the platform was rotating when it was not. Thus, simulator systems can be made more efficient by proper combination of platform and visual cues. Fourth, motion fidelity specifications were revised that now provide simulator users with a better prediction of motion fidelity based upon the frequency responses of their motion control laws. Fifth, vertical platform motion affected pilot estimates of steady-state altitude during altitude repositioning. Finally, the combined results led to a general method for configuring helicopter motion systems and for developing simulator tasks that more likely represent actual flight. The overall results can serve as a guide to future simulator designers and to today's operators.

Learning characteristics of a space-time neural network as a tether skiprope observer

NASA Technical Reports Server (NTRS)

Lea, Robert N.; Villarreal, James A.; Jani, Yashvant; Copeland, Charles

1993-01-01

The Software Technology Laboratory at the Johnson Space Center is testing a Space Time Neural Network (STNN) for observing tether oscillations present during retrieval of a tethered satellite. Proper identification of tether oscillations, known as 'skiprope' motion, is vital to safe retrieval of the tethered satellite. Our studies indicate that STNN has certain learning characteristics that must be understood properly to utilize this type of neural network for the tethered satellite problem. We present our findings on the learning characteristics including a learning rate versus momentum performance table.

Derivation of the Boltzmann Equation for Financial Brownian Motion: Direct Observation of the Collective Motion of High-Frequency Traders.

PubMed

Kanazawa, Kiyoshi; Sueshige, Takumi; Takayasu, Hideki; Takayasu, Misako

2018-03-30

A microscopic model is established for financial Brownian motion from the direct observation of the dynamics of high-frequency traders (HFTs) in a foreign exchange market. Furthermore, a theoretical framework parallel to molecular kinetic theory is developed for the systematic description of the financial market from microscopic dynamics of HFTs. We report first on a microscopic empirical law of traders' trend-following behavior by tracking the trajectories of all individuals, which quantifies the collective motion of HFTs but has not been captured in conventional order-book models. We next introduce the corresponding microscopic model of HFTs and present its theoretical solution paralleling molecular kinetic theory: Boltzmann-like and Langevin-like equations are derived from the microscopic dynamics via the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy. Our model is the first microscopic model that has been directly validated through data analysis of the microscopic dynamics, exhibiting quantitative agreements with mesoscopic and macroscopic empirical results.

Derivation of the Boltzmann Equation for Financial Brownian Motion: Direct Observation of the Collective Motion of High-Frequency Traders

NASA Astrophysics Data System (ADS)

Kanazawa, Kiyoshi; Sueshige, Takumi; Takayasu, Hideki; Takayasu, Misako

2018-03-01

A microscopic model is established for financial Brownian motion from the direct observation of the dynamics of high-frequency traders (HFTs) in a foreign exchange market. Furthermore, a theoretical framework parallel to molecular kinetic theory is developed for the systematic description of the financial market from microscopic dynamics of HFTs. We report first on a microscopic empirical law of traders' trend-following behavior by tracking the trajectories of all individuals, which quantifies the collective motion of HFTs but has not been captured in conventional order-book models. We next introduce the corresponding microscopic model of HFTs and present its theoretical solution paralleling molecular kinetic theory: Boltzmann-like and Langevin-like equations are derived from the microscopic dynamics via the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy. Our model is the first microscopic model that has been directly validated through data analysis of the microscopic dynamics, exhibiting quantitative agreements with mesoscopic and macroscopic empirical results.

Probing the Galactic Potential with Next-generation Observations of Disk Stars

NASA Astrophysics Data System (ADS)

Sumi, T.; Johnston, K. V.; Tremaine, S.; Spergel, D. N.; Majewski, S. R.

2009-07-01

Our current knowledge of the rotation curve of the Milky Way is remarkably poor compared to other galaxies, limited by the combined effects of extinction and the lack of large samples of stars with good distance estimates and proper motions. Near-future surveys promise a dramatic improvement in the number and precision of astrometric, photometric, and spectroscopic measurements of stars in the Milky Way's disk. We examine the impact of such surveys on our understanding of the Galaxy by "observing" particle realizations of nonaxisymmetric disk distributions orbiting in an axisymmetric halo with appropriate errors and then attempting to recover the underlying potential using a Markov Chain Monte Carlo approach. We demonstrate that the azimuthally averaged gravitational force field in the Galactic plane—and hence, to a lesser extent, the Galactic mass distribution—can be tightly constrained over a large range of radii using a variety of types of surveys so long as the error distribution of the measurements of the parallax, proper motion, and radial velocity are well understood and the disk is surveyed globally. One advantage of our method is that the target stars can be selected nonrandomly in real or apparent-magnitude space to ensure just such a global sample without biasing the results. Assuming that we can always measure the line-of-sight velocity of a star with at least 1 km s-1 precision, we demonstrate that the force field can be determined to better than ~1% for Galactocentric radii in the range R = 4-20 kpc using either: (1) small samples (a few hundred stars) with very accurate trigonometric parallaxes and good proper-motion measurements (uncertainties δ p,tri lsim 10 μas and δμ lsim 100 μas yr-1 respectively); (2) modest samples (~1000 stars) with good indirect parallax estimates (e.g., uncertainty in photometric parallax δ p,phot~ 10%-20%) and good proper-motion measurements (δμ ~ 100 μas yr-1) or (3) large samples (~104 stars) with good

Rotational and Translational Components of Motion Parallax: Observers' Sensitivity and Implications for Three-Dimensional Computer Graphics

NASA Technical Reports Server (NTRS)

Kaiser, Mary K.; Montegut, Michael J.; Proffitt, Dennis R.

1995-01-01

The motion of objects during motion parallax can be decomposed into 2 observer-relative components: translation and rotation. The depth ratio of objects in the visual field is specified by the inverse ratio of their angular displacement (from translation) or equivalently by the inverse ratio of their rotations. Despite the equal mathematical status of these 2 information sources, it was predicted that observers would be far more sensitive to the translational than rotational component. Such a differential sensitivity is implicitly assumed by the computer graphics technique billboarding, in which 3-dimensional (3-D) objects are drawn as planar forms (i.e., billboards) maintained normal to the line of sight. In 3 experiments, observers were found to be consistently less sensitive to rotational anomalies. The implications of these findings for kinetic depth effect displays and billboarding techniques are discussed.

Strong-motion observations of the M 7.8 Gorkha, Nepal, earthquake sequence and development of the N-shake strong-motion network

USGS Publications Warehouse

Dixit, Amod; Ringler, Adam; Sumy, Danielle F.; Cochran, Elizabeth S.; Hough, Susan E.; Martin, Stacey; Gibbons, Steven; Luetgert, James H.; Galetzka, John; Shrestha, Surya; Rajaure, Sudhir; McNamara, Daniel E.

2015-01-01

We present and describe strong-motion data observations from the 2015 M 7.8 Gorkha, Nepal, earthquake sequence collected using existing and new Quake-Catcher Network (QCN) and U.S. Geological Survey NetQuakes sensors located in the Kathmandu Valley. A comparison of QCN data with waveforms recorded by a conventional strong-motion (NetQuakes) instrument validates the QCN data. We present preliminary analysis of spectral accelerations, and peak ground acceleration and velocity for earthquakes up to M 7.3 from the QCN stations, as well as preliminary analysis of the mainshock recording from the NetQuakes station. We show that mainshock peak accelerations were lower than expected and conclude the Kathmandu Valley experienced a pervasively nonlinear response during the mainshock. Phase picks from the QCN and NetQuakes data are also used to improve aftershock locations. This study confirms the utility of QCN instruments to contribute to ground-motion investigations and aftershock response in regions where conventional instrumentation and open-access seismic data are limited. Initial pilot installations of QCN instruments in 2014 are now being expanded to create the Nepal–Shaking Hazard Assessment for Kathmandu and its Environment (N-SHAKE) network.

Auroral Proper Motion in the Era of AMISR and EMCCD

NASA Astrophysics Data System (ADS)

Semeter, J. L.

2016-12-01

The term "aurora" is a catch-all for luminosity produced by the deposition of magnetospheric energy in the outer atmosphere. The use of this single phenomenological term occludes the rich variety of sources and mechanisms responsible for the excitation. Among these are electron thermal conduction (SAR arcs), electrostatic potential fields ("inverted-V" aurora), wave-particle resonance (Alfvenic aurora, pulsating aurora), pitch-angle scattering (diffuse aurora), and direct injection of plasma sheet particles (PBIs, substorms). Much information about auroral energization has been derived from the energy spectrum of primary particles, which may be measured directly with an in situ detector or indirectly via analysis of the atmospheric response (e.g., auroral spectroscopy, tomography, ionization). Somewhat less emphasized has been the information in the B_perp dimension. Specifically, the scale-dependent motions of auroral forms in the rest frame of the ambient plasma provide a means of partitioning both the source region and the source mechanism. These results, in turn, affect ionospheric state parameters that control the M-I coupling process-most notably, the degree of structure imparted to the conductance field. This paper describes recent results enabled by the advent of two technologies: high frame-rate, high-resolution imaging detectors, and electronically steerable incoherent scatter radar (the AMISR systems). In addition to contributing to our understanding of the aurora, these results may be used in predictive models of multi-scale energy transfer within the disturbed geospace system.

Multi-Epoch 8.4GHz VLBI Observations of the Nucleus of Centaurus A

NASA Technical Reports Server (NTRS)

Meier, David L.

1992-01-01

We present the results of several 8.4 GHz VLBI observations of the nucleus of Centaurus A. We fing that the source possesses a classical core-jet structure with the inner portion of the jet expanding at a proper motion of 4.o mas yr or an apparet velocity of 0.26c along the jet.

Insensitivity of GNSS to geocenter motion through the network shift approach (Invited)

NASA Astrophysics Data System (ADS)

Rebischung, P.; Altamimi, Z.; Springer, T.

2013-12-01

As a satellite-based technique, GNSS should be sensitive to motions of the Earth's center of mass (CM) with respect to the Earth's crust. In theory, the weekly solutions of the Analysis Centers of the International GNSS Service (IGS ACs) should indeed have the "instantaneous" CM as their origin, and the net translations between the weekly AC frames and a secular frame such as ITRF2008 should thus approximate the non-linear motion of CM with respect to the Earth's center of figure. However, the comparison of the AC translation time series with each other, with SLR geocenter estimates or with geophysical models reveals that this way of observing geocenter motion with GNSS currently gives unreliable results. We addressed the problem of observing geocenter motion with GNSS through this network shift approach from the perspective of collinearity (or multicollinearity) among the parameters of a least-squares regression. A collinearity diagnosis, based on the notion of variance inflation factor, was therefore developed and allows handling several peculiarities of the GNSS geocenter determination problem. Its application reveals that the determination of all three components of geocenter motion with GNSS suffers from serious collinearity issues, with a comparable level as in the problem of determining the terrestrial scale simultaneously with the GNSS satellite phase center offsets. We show that the inability of current GNSS, as opposed to Satellite Laser Ranging (SLR), to properly sense geocenter motion is mostly explained by the estimation, in the GNSS case, of epoch-wise station and satellite clock offsets simultaneously with tropospheric parameters. The empirical satellite accelerations, as estimated by most IGS ACs, slightly amplify the collinearity of the Z geocenter coordinate, but their role remains secondary.

Motion and properties of nuclear radio components in Seyfert galaxies seen with VLBI

NASA Astrophysics Data System (ADS)

Middelberg, E.; Roy, A. L.; Nagar, N. M.; Krichbaum, T. P.; Norris, R. P.; Wilson, A. S.; Falcke, H.; Colbert, E. J. M.; Witzel, A.; Fricke, K. J.

2004-04-01

We report EVN, MERLIN and VLBA observations at 18 cm, 6 cm and 3.6 cm of the Seyfert galaxies NGC 7674, NGC 5506, NGC 2110 and Mrk 1210 to study their structure and proper motions on pc scales and to add some constraints on the many possible causes of the radio-quietness of Seyferts. The component configurations in NGC 7674 and NGC 2110 are simple, linear structures, whereas the configurations in NGC 5506 and Mrk 1210 have multiple components with no clear axis of symmetry. We suggest that NGC 7674 is a low-luminosity compact symmetric object. Comparing the images at different epochs, we find a proper motion in NGC 7674 of (0.92±0.07) c between the two central components separated by 282 pc and, in NGC 5506, we find a 3 σ upper limit of 0.50 c for the components separated by 3.8 pc. Our results confirm and extend earlier work showing that the outward motion of radio components in Seyfert galaxies is non-relativistic on pc scales. We briefly discuss whether this non-relativistic motion is intrinsic to the jet-formation process or results from deceleration of an initially relativistic jet by interaction with the pc or sub-pc scale interstellar medium. We combined our sample with a list compiled from the literature of VLBI observations made of Seyfert galaxies, and found that most Seyfert nuclei have at least one flat-spectrum component on the VLBI scale, which was not seen in the spectral indices measured at arcsec resolution. We found also that the bimodal alignment of pc and kpc radio structures displayed by radio galaxies and quasars is not displayed by this sample of Seyferts, which shows a uniform distribution of misalignment between 0° and 90°. The frequent misalignment could result from jet precession or from deflection of the jet by interaction with gas in the interstellar medium.

A slowly moving foreground can capture an observer's self-motion--a report of a new motion illusion: inverted vection.

PubMed

Nakamura, S; Shimojo, S

2000-01-01

We investigated interactions between foreground and background stimuli during visually induced perception of self-motion (vection) by using a stimulus composed of orthogonally moving random-dot patterns. The results indicated that, when the foreground moves with a slower speed, a self-motion sensation with a component in the same direction as the foreground is induced. We named this novel component of self-motion perception 'inverted vection'. The robustness of inverted vection was confirmed using various measures of self-motion sensation and under different stimulus conditions. The mechanism underlying inverted vection is discussed with regard to potentially relevant factors, such as relative motion between the foreground and background, and the interaction between the mis-registration of eye-movement information and self-motion perception.

Application of MCM image construction to IRAS comet observations

NASA Technical Reports Server (NTRS)

Schlapfer, Martin F.; Walker, Russell G.

1994-01-01

There is a wealth of IRAS comet data, obtained in both the survey and pointed observations modes. However, these measurements have remained largely untouched due to difficulties in removing instrumental effects from the data. We have developed a version of the Maximum Correlation Method for Image Construction algorithm (MCM) which operates in the moving coordinate system of the comet and properly treats both real cometary motion and apparent motion due to spacecraft parallax. This algorithm has been implemented on a 486/33 PC in FORTRAN and IDL codes. Preprocessing of the IRAS CRDD includes baseline removal, deglitching, and removal of long tails due to dielectric time constants of the detectors. The resulting images are virtually free from instrumental effects and have the highest possible spatial resolution consistent with the data sampling. We present examples of high resolution IRAS images constructed from survey observations of Comets P/Tempel 1 and P/Tempel 2, and pointed observations of IRAS-Araki-Alcock.

Construction of Lagrangians and Hamiltonians from the Equation of Motion

ERIC Educational Resources Information Center

Yan, C. C.

1978-01-01

Demonstrates that infinitely many Lagrangians and Hamiltonians can be constructed from a given equation of motion. Points out the lack of an established criterion for making a proper selection. (Author/GA)

New strong motion network in Georgia: basis for specifying seismic hazard

NASA Astrophysics Data System (ADS)

Kvavadze, N.; Tsereteli, N. S.

2017-12-01

Risk created by hazardous natural events is closely related to sustainable development of the society. Global observations have confirmed tendency of growing losses resulting from natural disasters, one of the most dangerous and destructive if which are earthquakes. Georgia is located in seismically active region. So, it is imperative to evaluate probabilistic seismic hazard and seismic risk with proper accuracy. National network of Georgia includes 35 station all of which are seismometers. There are significant gaps in strong motion recordings, which essential for seismic hazard assessment. To gather more accelerometer recordings, we have built a strong motion network distributed on the territory of Georgia. The network includes 6 stations for now, with Basalt 4x datalogger and strong motion sensor Episensor ES-T. For each site, Vs30 and soil resonance frequencies have been measured. Since all but one station (Tabakhmelam near Tbilisi), are located far from power and internet lines special system was created for instrument operation. Solar power is used to supply the system with electricity and GSM/LTE modems for internet access. VPN tunnel was set up using Raspberry pi, for two-way communication with stations. Tabakhmela station is located on grounds of Ionosphere Observatory, TSU and is used as a hub for the network. This location also includes a broadband seismometer and VLF electromagnetic waves observation antenna, for possible earthquake precursor studies. On server, located in Tabakhmela, the continues data is collected from all the stations, for later use. The recordings later will be used in different seismological and engineering problems, namely selecting and creating GMPE model for Caucasus, for probabilistic seismic hazard and seismic risk evaluation. These stations are a start and in the future expansion of strong motion network is planned. Along with this, electromagnetic wave observations will continue and additional antennas will be implemented

Directional topographic site response at Tarzana observed in aftershocks of the 1994 Northridge, California, earthquake: Implications for mainshock motions

USGS Publications Warehouse

Spudich, P.; Hellweg, M.; Lee, W.H.K.

1996-01-01

The Northridge earthquake caused 1.78 g acceleration in the east-west direction at a site in Tarzana, California, located about 6 km south of the mainshock epicenter. The accelerograph was located atop a hill about 15-m high, 500-m long, and 130-m wide, striking about N78??E. During the aftershock sequence, a temporary array of 21 three-component geophones was deployed in six radial lines centered on the accelerograph, with an average sensor spacing of 35 m. Station COO was located about 2 m from the accelerograph. We inverted aftershock spectra to obtain average relative site response at each station as a function of direction of ground motion. We identified a 3.2-Hz resonance that is a transverse oscillation of the hill (a directional topographic effect). The top/base amplification ratio at 3.2 Hz is about 4.5 for horizontal ground motions oriented approximately perpendicular to the long axis of the hill and about 2 for motions parallel to the hill. This resonance is seen most strongly within 50 m of COO. Other resonant frequencies were also observed. A strong lateral variation in attenuation, probably associated with a fault, caused substantially lower motion at frequencies above 6 Hz at the east end of the hill. There may be some additional scattered waves associated with the fault zone and seen at both the base and top of the hill, causing particle motions (not spectral ratios) at the top of the hill to be rotated about 20?? away from the direction transverse to the hill. The resonant frequency, but not the amplitude, of our observed topographic resonance agrees well with theory, even for such a low hill. Comparisons of our observations with theoretical results indicate that the 3D shape of the hill and its internal structure are important factors affecting its response. The strong transverse resonance of the hill does not account for the large east-west mainshock motions. Assuming linear soil response, mainshock east-west motions at the Tarzana accelerograph

Brief communication: The global signature of post-1900 land ice wastage on vertical land motion

NASA Astrophysics Data System (ADS)

Riva, Riccardo E. M.; Frederikse, Thomas; King, Matt A.; Marzeion, Ben; van den Broeke, Michiel R.

2017-06-01

Melting glaciers, ice caps and ice sheets have made an important contribution to sea-level rise through the last century. Self-attraction and loading effects driven by shrinking ice masses cause a spatially varying redistribution of ocean waters that affects reconstructions of past sea level from sparse observations. We model the solid-earth response to ice mass changes and find significant vertical deformation signals over large continental areas. We show how deformation rates have been strongly varying through the last century, which implies that they should be properly modelled before interpreting and extrapolating recent observations of vertical land motion and sea-level change.

Motion of single wandering diblock-macromolecules directed by a PTFE nano-fence: real time SFM observations.

PubMed

Gallyamov, Marat O; Qin, Shuhui; Matyjaszewski, Krzysztof; Khokhlov, Alexei; Möller, Martin

2009-07-21

Using SFM we have observed a peculiar twisting motion of diblock macromolecules pre-collapsed in ethanol vapour during their subsequent spreading in water vapour. The intrinsic asymmetry of the diblock macromolecules has been considered to be the reason for such twisting. Further, friction-deposited PTFE nano-stripes have been employed as nano-trails with the purpose of inducing lateral directed motion of the asymmetric diblock macromolecules under cyclic impact from the changing vapour surroundings. Indeed, some of the macromolecules have demonstrated a certain tendency to orient along the PTFE stripes, and some of the oriented ones have moved occasionally in a directed manner along the trail. However, it has been difficult to reliably record such directed motion at the single molecule level due to some mobility of the PTFE nano-trails themselves in the changing vapour environment. In vapours, the PTFE stripes have demonstrated a distinct tendency towards conjunction. This tendency has manifested itself in efficient expelling of groups of the mobile brush-like molecules from the areas between two PTFE stripes joining in a zip-fastener manner. This different kind of vapour-induced cooperative macromolecular motion has been reliably observed as being directed. The PTFE nano-frame experiences some deformation when constraining the spreading macromolecules. We have estimated the possible force causing such deformation of the PTFE fence. The force has been found to be a few pN as calculated by a partial contribution from every single molecule of the constrained group.

8 March 2010 Elazığ-Kovancilar (Turkey) Earthquake: observations on ground motions and building damage

USGS Publications Warehouse

Akkar, Sinan; Aldemir, A.; Askan, A.; Bakir, S.; Canbay, E.; Demirel, I.O.; Erberik, M.A.; Gulerce, Z.; Gulkan, Polat; Kalkan, Erol; Prakash, S.; Sandikkaya, M.A.; Sevilgen, V.; Ugurhan, B.; Yenier, E.

2011-01-01

An earthquake of MW = 6.1 occurred in the Elazığ region of eastern Turkey on 8 March 2010 at 02:32:34 UTC. The United States Geological Survey (USGS) reported the epicenter of the earthquake as 38.873°N-39.981°E with a focal depth of 12 km. Forty-two people lost their lives and 137 were injured during the event. The earthquake was reported to be on the left-lateral strike-slip east Anatolian fault (EAF), which is one of the two major active fault systems in Turkey. Teams from the Earthquake Engineering Research Center of the Middle East Technical University (EERC-METU) visited the earthquake area in the aftermath of the mainshock. Their reconnaissance observations were combined with interpretations of recorded ground motions for completeness. This article summarizes observations on building and ground damage in the area and provides a discussion of the recorded motions. No significant observations in terms of geotechnical engineering were made.

Astrometric and photometric measurements of binary stars with adaptive optics: observations from 2001 to 2006

NASA Astrophysics Data System (ADS)

Roberts, Lewis C.; Mason, Brian D.

2018-02-01

The adaptive optics system at the 3.6 m Advanced Electro-Optical System telescope was used to measure the astrometry and differential magnitude in I band of binary star systems between 2002 and 2006. We report 413 astrometric and photometric measurements of 373 stellar pairs. The astrometric measurements will be of use for future orbital determination, and the photometric measurements will be of use in estimating the spectral types of the component stars. For 21 binaries that had not been observed in decades, we are able to confirm that the systems share common proper motion. Candidate new companions were detected in 24 systems; for these we show the discovery images. Follow-up observations should be able to determine if these systems share common proper motion and are gravitationally bound objects. We computed orbits for nine binaries. Of these, the orbits of five systems are improved compared to prior orbits and four systems have their orbits computed for the first time. In addition, 315 stars were unresolved and the full-width half maxima of the images are presented.

Astrometry and dynamics of Solar System Objects with Gaia GDR observations and catalogues

NASA Astrophysics Data System (ADS)

Hestroffer, Daniel J. G. J.; Tanga, Paolo

2017-06-01

The Gaia ESA space mission has started to provide its harvest with the first Gaia data release DR1, published in September 2016. Gaia DR1 provides positions for about 1 billion stars and proper motion for the Tycho-Gaia TGAS of 2 million stars with unprecedented accuracy. The second data release DR2 will be the major step in the Gaia mission, providing all astrometric parameters (including parallax and proper motion) for a billion stars, in an absolute reference frame - to become the optical ICRF. Gaia DR2 will also provide epoch astrometry for about 13000 asteroids from its direct observations, down to magnitude V≈20.7. We will discuss the improvement brought by Gaia over 5 years of nominal mission, starting with DR1, and focusing especially on the dynamics of asteroids and other Solar System Objects. This includes use of the catalogue for calibrating future and past photometric and astrometric observations (in particular new reduction of ancient photographic plates digitalised by the NAROO programme), new perspectives for orbit determination and stellar occultations, detection of small acceleration or perturbations for the asteroids. Also we illustrate the ground-based activity coordinated by the Gaia-FUN-SSO network for follow-up observations of newly discovered Near Earth Object.

Bayesian approach to MSD-based analysis of particle motion in live cells.

PubMed

Monnier, Nilah; Guo, Syuan-Ming; Mori, Masashi; He, Jun; Lénárt, Péter; Bathe, Mark

2012-08-08

Quantitative tracking of particle motion using live-cell imaging is a powerful approach to understanding the mechanism of transport of biological molecules, organelles, and cells. However, inferring complex stochastic motion models from single-particle trajectories in an objective manner is nontrivial due to noise from sampling limitations and biological heterogeneity. Here, we present a systematic Bayesian approach to multiple-hypothesis testing of a general set of competing motion models based on particle mean-square displacements that automatically classifies particle motion, properly accounting for sampling limitations and correlated noise while appropriately penalizing model complexity according to Occam's Razor to avoid over-fitting. We test the procedure rigorously using simulated trajectories for which the underlying physical process is known, demonstrating that it chooses the simplest physical model that explains the observed data. Further, we show that computed model probabilities provide a reliability test for the downstream biological interpretation of associated parameter values. We subsequently illustrate the broad utility of the approach by applying it to disparate biological systems including experimental particle trajectories from chromosomes, kinetochores, and membrane receptors undergoing a variety of complex motions. This automated and objective Bayesian framework easily scales to large numbers of particle trajectories, making it ideal for classifying the complex motion of large numbers of single molecules and cells from high-throughput screens, as well as single-cell-, tissue-, and organism-level studies. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Helicopter flight simulation motion platform requirements

NASA Astrophysics Data System (ADS)

Schroeder, Jeffery Allyn

Flight simulators attempt to reproduce in-flight pilot-vehicle behavior on the ground. This reproduction is challenging for helicopter simulators, as the pilot is often inextricably dependent on external cues for pilot-vehicle stabilization. One important simulator cue is platform motion; however, its required fidelity is unknown. To determine the required motion fidelity, several unique experiments were performed. A large displacement motion platform was used that allowed pilots to fly tasks with matched motion and visual cues. Then, the platform motion was modified to give cues varying from full motion to no motion. Several key results were found. First, lateral and vertical translational platform cues had significant effects on fidelity. Their presence improved performance and reduced pilot workload. Second, yaw and roll rotational platform cues were not as important as the translational platform cues. In particular, the yaw rotational motion platform cue did not appear at all useful in improving performance or reducing workload. Third, when the lateral translational platform cue was combined with visual yaw rotational cues, pilots believed the platform was rotating when it was not. Thus, simulator systems can be made more efficient by proper combination of platform and visual cues. Fourth, motion fidelity specifications were revised that now provide simulator users with a better prediction of motion fidelity based upon the frequency responses of their motion control laws. Fifth, vertical platform motion affected pilot estimates of steady-state altitude during altitude repositionings. This refutes the view that pilots estimate altitude and altitude rate in simulation solely from visual cues. Finally, the combined results led to a general method for configuring helicopter motion systems and for developing simulator tasks that more likely represent actual flight. The overall results can serve as a guide to future simulator designers and to today's operators.

A new imaging technique on strength and phase of pulsatile tissue-motion in brightness-mode ultrasonogram

NASA Astrophysics Data System (ADS)

Fukuzawa, Masayuki; Yamada, Masayoshi; Nakamori, Nobuyuki; Kitsunezuka, Yoshiki

2007-03-01

A new imaging technique has been developed for observing both strength and phase of pulsatile tissue-motion in a movie of brightness-mode ultrasonogram. The pulsatile tissue-motion is determined by evaluating the heartbeat-frequency component in Fourier transform of a series of pixel value as a function of time at each pixel in a movie of ultrasonogram (640x480pixels/frame, 8bit/pixel, 33ms/frame) taken by a conventional ultrasonograph apparatus (ATL HDI5000). In order to visualize both the strength and the phase of the pulsatile tissue-motion, we propose a pulsatile-phase image that is obtained by superimposition of color gradation proportional to the motion phase on the original ultrasonogram only at which the motion strength exceeds a proper threshold. The pulsatile-phase image obtained from a cranial ultrasonogram of normal neonate clearly reveals that the motion region gives good agreement with the anatomical shape and position of the middle cerebral artery and the corpus callosum. The motion phase is fluctuated with the shape of arteries revealing local obstruction of blood flow. The pulsatile-phase images in the neonates with asphyxia at birth reveal decreases of the motion region and increases of the phase fluctuation due to the weakness and local disturbance of blood flow, which is useful for pediatric diagnosis.

High-frequency ground-motion parameters from weak-motion data in the Sicily Channel and surrounding regions

NASA Astrophysics Data System (ADS)

D'Amico, Sebastiano; Akinci, Aybige; Pischiutta, Marta

2018-07-01

In this paper we characterize the high-frequency (1.0-10 Hz) seismic wave crustal attenuation and the source excitation in the Sicily Channel and surrounding regions using background seismicity from weak-motion database. The data set includes 15 995 waveforms related to earthquakes having local magnitude ranging from 2.0 to 4.5 recorded between 2006 and 2012. The observed and predicted ground motions form the weak-motion data are evaluated in several narrow frequency bands from 0.25 to 20.0 Hz. The filtered observed peaks are regressed to specify a proper functional form for the regional attenuation, excitation and site specific term separately. The results are then used to calibrate effective theoretical attenuation and source excitation models using the random vibration theory. In the log-log domain, the regional seismic wave attenuation and the geometrical spreading coefficient are modelled together. The geometrical spreading coefficient, g(r), modelled with a bilinear piecewise functional form and given as g(r) ∝ r-1.0 for the short distances (r < 50 km) and as g(r) ∝ r-0.8 for the larger distances (r < 50 km). A frequency-dependent quality factor, inverse of the seismic attenuation parameter, Q(f)=160f/fref0. 35 (where fref = 1.0 Hz), is combined to the geometrical spreading. The source excitation terms are defined at a selected reference distance with a magnitude-independent roll-off spectral parameter, κ 0.04 s and with a Brune stress drop parameter increasing with moment magnitude, from Δσ = 2 MPa for Mw = 2.0 to Δσ = 13 MPa for Mw = 4.5. For events M ≤ 4.5 (being Mwmax = 4.5 available in the data set) the stress parameters are obtained by correlating the empirical/excitation source spectra with the Brune spectral model as function of magnitude. For the larger magnitudes (Mw>4.5) outside the range available in the calibration data set where we do not have recorded data, we extrapolate our results through the calibration of the stress parameters

Visual and Non-Visual Contributions to the Perception of Object Motion during Self-Motion

PubMed Central

Fajen, Brett R.; Matthis, Jonathan S.

2013-01-01

Many locomotor tasks involve interactions with moving objects. When observer (i.e., self-)motion is accompanied by object motion, the optic flow field includes a component due to self-motion and a component due to object motion. For moving observers to perceive the movement of other objects relative to the stationary environment, the visual system could recover the object-motion component – that is, it could factor out the influence of self-motion. In principle, this could be achieved using visual self-motion information, non-visual self-motion information, or a combination of both. In this study, we report evidence that visual information about the speed (Experiment 1) and direction (Experiment 2) of self-motion plays a role in recovering the object-motion component even when non-visual self-motion information is also available. However, the magnitude of the effect was less than one would expect if subjects relied entirely on visual self-motion information. Taken together with previous studies, we conclude that when self-motion is real and actively generated, both visual and non-visual self-motion information contribute to the perception of object motion. We also consider the possible role of this process in visually guided interception and avoidance of moving objects. PMID:23408983

High-Frequency Ground-Motion Parameters from Weak-Motion Data in the Sicily Channel and Surrounding Regions

NASA Astrophysics Data System (ADS)

D'Amico, Sebastiano; Akinci, Aybige; Pischiutta, Marta

2018-03-01

In this paper we characterize the high frequency (1.0 - 10 Hz) seismic wave crustal attenuation and the source excitation in the Sicily Channel and surrounding regions using background seismicity from weak-motion database. The data set includes 15995 waveforms related to earthquakes having local magnitude ranging from 2.0 to 4.5 recorded between 2006 and 2012. The observed and predicted ground motions form the weak-motion data are evaluated in several narrow frequency bands from 0.25 to 20.0 Hz. The filtered observed peaks are regressed to specify a proper functional form for the regional attenuation, excitation and site specific term separately. The results are then used to calibrate effective theoretical attenuation and source excitation models using the Random Vibration Theory (RVT). In the log-log domain, the regional seismic wave attenuation and the geometrical spreading coefficient are modeled together. The geometrical spreading coefficient, g (r), modeled with a bilinear piecewise functional form and given as g (r) ∝ r-1.0 for the short distances (r < 50 km) and as g (r) ∝ r-0.8 for the larger distances (r < 50 km). A frequency-dependent quality factor, inverse of the seismic attenuation parameter, Q(f) = 160 f/fref 0. 35 (where fref = 1.0 Hz), is combined to the geometrical spreading. The source excitation terms are defined at a selected reference distance with a magnitude independent roll-off spectral parameter, κ 0.04 s and with a Brune stress drop parameter increasing with moment magnitude, from Δσ = 2 MPa for Mw = 2.0 to Δσ = 13 MPa for Mw = 4.5. For events M≤4.5 (being Mwmax = 4.5 available in the dataset) the stress parameters are obtained by correlating the empirical/excitation source spectra with the Brune spectral model as function of magnitude. For the larger magnitudes (Mw>4.5) outside the range available in the calibration dataset where we do not have recorded data, we extrapolate our results through the calibration of the stress

The Quake-Catcher Network: Improving Earthquake Strong Motion Observations Through Community Engagement

NASA Astrophysics Data System (ADS)

Cochran, E. S.; Lawrence, J. F.; Christensen, C. M.; Chung, A. I.; Neighbors, C.; Saltzman, J.

2010-12-01

The Quake-Catcher Network (QCN) involves the community in strong motion data collection by utilizing volunteer computing techniques and low-cost MEMS accelerometers. Volunteer computing provides a mechanism to expand strong-motion seismology with minimal infrastructure costs, while promoting community participation in science. Micro-Electro-Mechanical Systems (MEMS) triaxial accelerometers can be attached to a desktop computer via USB and are internal to many laptops. Preliminary shake table tests show the MEMS accelerometers can record high-quality seismic data with instrument response similar to research-grade strong-motion sensors. QCN began distributing sensors and software to K-12 schools and the general public in April 2008 and has grown to roughly 1500 stations worldwide. We also recently tested whether sensors could be quickly deployed as part of a Rapid Aftershock Mobilization Program (RAMP) following the 2010 M8.8 Maule, Chile earthquake. Volunteers are recruited through media reports, web-based sensor request forms, as well as social networking sites. Using data collected to date, we examine whether a distributed sensing network can provide valuable seismic data for earthquake detection and characterization while promoting community participation in earthquake science. We utilize client-side triggering algorithms to determine when significant ground shaking occurs and this metadata is sent to the main QCN server. On average, trigger metadata are received within 1-10 seconds from the observation of a trigger; the larger data latencies are correlated with greater server-station distances. When triggers are detected, we determine if the triggers correlate to others in the network using spatial and temporal clustering of incoming trigger information. If a minimum number of triggers are detected then a QCN-event is declared and an initial earthquake location and magnitude is estimated. Initial analysis suggests that the estimated locations and magnitudes are

The Minkowski metric in non-inertial observer radar coordinates

NASA Astrophysics Data System (ADS)

Minguzzi, E.

2005-12-01

We give a closed expression for the Minkowski (1+1)-dimensional metric in the radar coordinates of an arbitrary non-inertial observer O in terms of O's proper acceleration. Knowledge of the metric allows the non-inertial observer to perform experiments in spacetime without making reference to inertial frames. To clarify the relation between inertial and non-inertial observers the coordinate transformation between radar and inertial coordinates also is given. We show that every conformally flat coordinate system can be regarded as the radar coordinate system of a suitable observer for a suitable parametrization of the observer worldline. Therefore, the coordinate transformation between arbitrarily moving observers is a conformal transformation and conformally invariant (1+1)-dimensional theories lead to the same physics for all observers, independently of their relative motion.

The Coordination Dynamics of Observational Learning: Relative Motion Direction and Relative Phase as Informational Content Linking Action-Perception to Action-Production.

PubMed

Buchanan, John J

2016-01-01

The primary goal of this chapter is to merge together the visual perception perspective of observational learning and the coordination dynamics theory of pattern formation in perception and action. Emphasis is placed on identifying movement features that constrain and inform action-perception and action-production processes. Two sources of visual information are examined, relative motion direction and relative phase. The visual perception perspective states that the topological features of relative motion between limbs and joints remains invariant across an actor's motion and therefore are available for pickup by an observer. Relative phase has been put forth as an informational variable that links perception to action within the coordination dynamics theory. A primary assumption of the coordination dynamics approach is that environmental information is meaningful only in terms of the behavior it modifies. Across a series of single limb tasks and bimanual tasks it is shown that the relative motion and relative phase between limbs and joints is picked up through visual processes and supports observational learning of motor skills. Moreover, internal estimations of motor skill proficiency and competency are linked to the informational content found in relative motion and relative phase. Thus, the chapter links action to perception and vice versa and also links cognitive evaluations to the coordination dynamics that support action-perception and action-production processes.

Observed ground-motion variabilities and implication for source properties

NASA Astrophysics Data System (ADS)

Cotton, F.; Bora, S. S.; Bindi, D.; Specht, S.; Drouet, S.; Derras, B.; Pina-Valdes, J.

2016-12-01

One of the key challenges of seismology is to be able to calibrate and analyse the physical factors that control earthquake and ground-motion variabilities. Within the framework of empirical ground-motion prediction equation (GMPE) developments, ground-motions residuals (differences between recorded ground motions and the values predicted by a GMPE) are computed. The exponential growth of seismological near-field records and modern regression algorithms allow to decompose these residuals into between-event and a within-event residual components. The between-event term quantify all the residual effects of the source (e.g. stress-drops) which are not accounted by magnitude term as the only source parameter of the model. Between-event residuals provide a new and rather robust way to analyse the physical factors that control earthquake source properties and associated variabilities. We first will show the correlation between classical stress-drops and between-event residuals. We will also explain why between-event residuals may be a more robust way (compared to classical stress-drop analysis) to analyse earthquake source-properties. We will finally calibrate between-events variabilities using recent high-quality global accelerometric datasets (NGA-West 2, RESORCE) and datasets from recent earthquakes sequences (Aquila, Iquique, Kunamoto). The obtained between-events variabilities will be used to evaluate the variability of earthquake stress-drops but also the variability of source properties which cannot be explained by a classical Brune stress-drop variations. We will finally use the between-event residual analysis to discuss regional variations of source properties, differences between aftershocks and mainshocks and potential magnitude dependencies of source characteristics.

WORM - WINDOWED OBSERVATION OF RELATIVE MOTION

NASA Technical Reports Server (NTRS)

Bauer, F.

1994-01-01

The Windowed Observation of Relative Motion, WORM, program is primarily intended for the generation of simple X-Y plots from data created by other programs. It allows the user to label, zoom, and change the scale of various plots. Three dimensional contour and line plots are provided, although with more limited capabilities. The input data can be in binary or ASCII format, although all data must be in the same format. A great deal of control over the details of the plot is provided, such as gridding, size of tick marks, colors, log/semilog capability, time tagging, and multiple and phase plane plots. Many color and monochrome graphics terminals and hard copy printer/plotters are supported. The WORM executive commands, menu selections and macro files can be used to develop plots and tabular data, query the WORM Help library, retrieve data from input files, and invoke VAX DCL commands. WORM generated plots are displayed on local graphics terminals and can be copied using standard hard copy capabilities. Some of the graphics features of WORM include: zooming and dezooming various portions of the plot; plot documentation including curve labeling and function listing; multiple curves on the same plot; windowing of multiple plots and insets of the same plot; displaying a specific on a curve; and spinning the curve left, right, up, and down. WORM is written in PASCAL for interactive execution and has been implemented on a DEC VAX computer operating under VMS 4.7 with a virtual memory requirement of approximately 392K of 8 bit bytes. It uses the QPLOT device independent graphics library included with WORM. It was developed in 1988.

Feeling-of-knowing for proper names.

PubMed

Izaute, Marie; Chambres, Patrick; Larochelle, Serge

2002-12-01

The main objective of the presented study was to study feeling-of-knowing (FOK) in proper name retrieval. Many studies show that FOK can predict performance on a subsequent criterion test. Although feeling-of-knowing studies involve questions about proper names, none make this distinction between proper names and common names. Nevertheless, the specific character of proper names as a unique label referring to a person should allow participants to target precisely the desired verbal label. Our idea here was that the unique character of proper name information should result in more accurate FOK evaluations. In the experiment, participants evaluated feeling-of-knowing for proper and common name descriptions. The study demonstrates that FOK judgments are more accurate for proper names than for common names. The implications of the findings for proper names are briefly discussed in terms of feeling-of-knowing hypotheses.

Objects in Motion

ERIC Educational Resources Information Center

Damonte, Kathleen

2004-01-01

One thing scientists study is how objects move. A famous scientist named Sir Isaac Newton (1642-1727) spent a lot of time observing objects in motion and came up with three laws that describe how things move. This explanation only deals with the first of his three laws of motion. Newton's First Law of Motion says that moving objects will continue…

Three-dimensional intrafractional internal target motions in accelerated partial breast irradiation using three-dimensional conformal external beam radiotherapy.

PubMed

Hirata, Kimiko; Yoshimura, Michio; Mukumoto, Nobutaka; Nakamura, Mitsuhiro; Inoue, Minoru; Sasaki, Makoto; Fujimoto, Takahiro; Yano, Shinsuke; Nakata, Manabu; Mizowaki, Takashi; Hiraoka, Masahiro

2017-07-01

We evaluated three-dimensional intrafractional target motion, divided into respiratory-induced motion and baseline drift, in accelerated partial breast irradiation (APBI). Paired fluoroscopic images were acquired simultaneously using orthogonal kV X-ray imaging systems at pre- and post-treatment for 23 patients who underwent APBI with external beam radiotherapy. The internal target motion was calculated from the surgical clips placed around the tumour cavity. The peak-to-peak respiratory-induced motions ranged from 0.6 to 1.5mm in all directions. A systematic baseline drift of 1.5mm towards the posterior direction and a random baseline drift of 0.3mm in the lateral-medial and cranial-caudal directions were observed. The baseline for an outer tumour cavity drifted towards the lateral and posterior directions, and that for an upper tumour cavity drifted towards the cranial direction. Moderate correlations were observed between the posterior baseline drift and the patients' physical characteristics. The posterior margin for intrafractional uncertainties was larger than 5mm in patients with greater fat thickness due to the baseline drift. The magnitude of the intrafractional motion was not uniform according to the direction, patients' physical characteristics, or tumour cavity location due to the baseline drift. Therefore, the intrafractional systematic movement should be properly managed. Copyright © 2017 Elsevier B.V. All rights reserved.

The facing bias in biological motion perception: Effects of stimulus gender and observer sex.

PubMed

Schouten, Ben; Troje, Nikolaus F; Brooks, Anna; van der Zwan, Rick; Verfaillie, Karl

2010-07-01

Under orthographic projection, biological motion point-light walkers offer no cues to the order of the dots in depth: Views from the front and from the back result in the very same stimulus. Yet observers show a bias toward seeing a walker facing the viewer (Vanrie, Dekeyser, & Verfaillie, 2004). Recently, we reported that this facing bias strongly depends on the gender of the walker (Brooks et al., 2008). The goal of the present study was, first, to examine the robustness of the effect by testing a much larger subject sample and, second, to investigate whether the effect depends on observer sex. Despite the fact that we found a significant effect of figure gender, we clearly failed to replicate the strong effect observed in the original study. We did, however, observe a significant interaction between figure gender and observer sex.

Very-long-baseline radio interferometry observations of low power radio galaxies.

PubMed Central

Giovannini, G; Cotton, W D; Feretti, L; Lara, L; Venturi, T; Marcaide, J M

1995-01-01

The parsec scale properties of low power radio galaxies are reviewed here, using the available data on 12 Fanaroff-Riley type I galaxies. The most frequent radio structure is an asymmetric parsec-scale morphology--i.e., core and one-sided jet. It is shared by 9 (possibly 10) of the 12 mapped radio galaxies. One (possibly 2) of the other galaxies has a two-sided jet emission. Two sources are known from published data to show a proper motion; we present here evidence for proper motion in two more galaxies. Therefore, in the present sample we have 4 radio galaxies with a measured proper motion. One of these has a very symmetric structure and therefore should be in the plane of the sky. The results discussed here are in agreement with the predictions of the unified scheme models. Moreover, the present data indicate that the parsec scale structure in low and high power radio galaxies is essentially the same. PMID:11607596

Effects of action observation therapy on upper extremity function, daily activities and motion evoked potential in cerebral infarction patients.

PubMed

Fu, Jianming; Zeng, Ming; Shen, Fang; Cui, Yao; Zhu, Meihong; Gu, Xudong; Sun, Ya

2017-10-01

The aim of this study was to explore the effects of action observation therapy on motor function of upper extremity, activities of daily living, and motion evoked potential in cerebral infarction patients. Cerebral infarction survivors were randomly assigned to an experimental group (28 patients) or a control group (25 patients). The conventional rehabilitation treatments were applied in both groups, but the experimental group received an additional action observation therapy for 8 weeks (6 times per week, 20 minutes per time). Fugl-Meyer assessment (FMA), Wolf Motor Function Test (WMFT), Modified Barthel Index (MBI), and motor evoked potential (MEP) were used to evaluate the upper limb movement function and daily life activity. There were no significant differences between experiment and control group in the indexes, including FMA, WMFT, and MBI scores, before the intervention. However, after 8 weeks treatments, these indexes were improved significantly. MEP latency and center-motion conduction time (CMCT) decreased from 23.82 ± 2.16 and 11.15 ± 1.68 to 22.69 ± 2.11 and 10.12 ± 1.46 ms. MEP amplitude increased from 0.61 ± 0.22 to 1.25 ± 0.38 mV. A remarkable relationship between the evaluations indexes of MEP and FMA was found. Combination of motion observation and traditional upper limb rehabilitation treatment technology can significantly elevate the movement function of cerebral infarction patients in subacute seizure phase with upper limb dysfunction, which expanded the application range of motion observation therapy and provided an effective therapy strategy for upper extremities hemiplegia in stroke patients.

New Astronomical Reduction of Old Observations (the NAROO project)

NASA Astrophysics Data System (ADS)

Arlot, Jean-Eudes; Robert, Vincent; Lainey, Valery; Neiner, Coralie; Thouvenin, Nicolas

2018-04-01

The Gaia astrometric reference catalogue will provide star proper motions with an accuracy of one mas one century ago for stars of magnitude 14 or brighter. Our project is to re-reduced the old observations with the new catalogue allowing to have an astrometric accuracy only limited by the observational biases and not by reference stars. Then, we plan to get an accuracy of 50 mas where the old reductions were not better than 500 mas! For our purpose, we will digitize old photographic plates with a sub-micrometric scanner. Tests were made using the UCAC catalogue showing that old photographic plates have an intrinsect accuracy of 30 to 60 mas.

OBSERVER RATING VERSUS THREE-DIMENSIONAL MOTION ANALYSIS OF LOWER EXTREMITY KINEMATICS DURING FUNCTIONAL SCREENING TESTS: A SYSTEMATIC REVIEW.

PubMed

Maclachlan, Liam; White, Steven G; Reid, Duncan

2015-08-01

Functional assessments are conducted in both clinical and athletic settings in an attempt to identify those individuals who exhibit movement patterns that may increase their risk of non-contact injury. In place of highly sophisticated three-dimensional motion analysis, functional testing can be completed through observation. To evaluate the validity of movement observation assessments by summarizing the results of articles comparing human observation in real-time or video play-back and three-dimensional motion analysis of lower extremity kinematics during functional screening tests. Systematic review. A computerized systematic search was conducted through Medline, SPORTSdiscus, Scopus, Cinhal, and Cochrane health databases between February and April of 2014. Validity studies comparing human observation (real-time or video play-back) to three-dimensional motion analysis of functional tasks were selected. Only studies comprising uninjured, healthy subjects conducting lower extremity functional assessments were appropriate for review. Eligible observers were certified health practitioners or qualified members of sports and athletic training teams that conduct athlete screening. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) was used to appraise the literature. Results are presented in terms of functional tasks. Six studies met the inclusion criteria. Across these studies, two-legged squats, single-leg squats, drop-jumps, and running and cutting manoeuvres were the functional tasks analysed. When compared to three-dimensional motion analysis, observer ratings of lower extremity kinematics, such as knee position in relation to the foot, demonstrated mixed results. Single-leg squats achieved target sensitivity values (≥ 80%) but not specificity values (≥ 50%>%). Drop-jump task agreement ranged from poor (< 50%) to excellent (> 80%). Two-legged squats achieved 88% sensitivity and 85% specificity. Mean underestimations as large as 198 (peak knee

Lagrangian equations of motion of particles and photons in a Schwarzschild field

NASA Astrophysics Data System (ADS)

Ritus, V. I.

2015-11-01

The equations of motion of a particle in the gravitational field of a black hole are considered in a formulation that uses generalized coordinates, velocities, and accelerations and is convenient for finding the integrals of motion. The equations are rewritten in terms of the physical velocities and accelerations measured in the Schwarzschild frame by a stationary observer using proper local length and time standards. The attractive force due to the field and the centripetal acceleration of a particle is proportional to the particle kinetic energy m/\\sqrt{1 - v^2}, consistently with the fact that the particle kinetic energy and the photon energy \\hbarω in the field increase by the same factor compared with their values without a field. The attraction exerted on particles and photons by a gravitational field source is proportional to their kinetic energies. The particle trajectory in the ultrarelativistic limit v \\to 1 coincides with the photon trajectory.

Spontaneous mode-selection in the self-propelled motion of a solid/liquid composite driven by interfacial instability

NASA Astrophysics Data System (ADS)

Takabatake, Fumi; Magome, Nobuyuki; Ichikawa, Masatoshi; Yoshikawa, Kenichi

2011-03-01

Spontaneous motion of a solid/liquid composite induced by a chemical Marangoni effect, where an oil droplet attached to a solid soap is placed on a water phase, was investigated. The composite exhibits various characteristic motions, such as revolution (orbital motion) and translational motion. The results showed that the mode of this spontaneous motion switches with a change in the size of the solid scrap. The essential features of this mode-switching were reproduced by ordinary differential equations by considering nonlinear friction with proper symmetry.

Local Nanomechanical Motion In Single Cells.

NASA Astrophysics Data System (ADS)

Pelling, Andrew; Gimzewski, James

2004-03-01

We present new evidence that the nanoscale motion of the cell wall of Saccharomyces cerevisiae exhibits local bionanomechanical motion at characteristic frequencies and which is not caused by random or Brownian processes. This motion is measured with the AFM tip which acts as a nanomechanical sensor, permitting the motion of the cell wall to be recorded as a function of time, applied force, etc. We present persuasive evidence which shows that the local nanomechanical motion is characteristic of metabolic processes taking place inside the cell. This is demonstrated by clear differences between living cells and living cells treated with a metabolic inhibitor. This inhibitor specifically targets cytochrome oxidase inside the mitochondria and inhibits ATP production. The cells observed in this study display characteristic local cell wall motion with amplitudes between 1 and 3 nm and frequencies between 500 and 1700 Hz. The motion is temperature dependant which also suggests the mechanism for the observed motion has biological origins. In addition to a stringent series of control experiments we also discuss local measurements of the cell's mechanical properties and their influence on the observed bionanomechanical motion.

Discriminating different type waves from pressure and ground motion observation in the seafloor by DONET cabled observation network.

NASA Astrophysics Data System (ADS)

Araki, E.; Kawaguchi, K.; Kaneda, Y.

2011-12-01

We developed and deployed seafloor cabled observatory called "Dense Ocean-floor Network for Earthquake and Tsunamis (DONET)" in the Nankai Trough, south of Japan. The main purpose of the DONET network is to observe large earthquake such as Tonankai earthquake in the deployed seafloor and associate Tsunamis in real-time to help disaster mitigation, and as well to monitor inter-seismic crustal activities such as micro earthquakes, very low frequency earthquakes, and slower crustal deformation. In each DONET seafloor observatory, high-sensitive broadband set of instruments for seismic and seafloor pressure monitoring, consisted from Guralp CMG3T broadband seismometer, Metrozet TSA100S accelerometer, Paroscientific 8B7000-2 pressure gauge, a deep-sea differential pressure gauge, a hydrophone, and a seawater thermometer, are installed. The density of seafloor observatories are 20 observatories distributed in 15-30 km interval which is optimized for monitoring of events in the plate boundary beneath the network. DONET may be regarded as a large-scale, high sensitive high density seismic array for monitoring teleseismic events in the Philippine Sea and the Pacific Ocean. The DONET seafloor observatories are situated in wide range of seafloor depth between 1800m and 4500m, from the seafloor basin about 50 km off Japanese Island through the slope of accerecionary prism to the deep trench axis 150 km off the coast, that may also regarded as a vertical array in the 4.5km thick ocean. This variation of depths helps identify T-phases from the array record. In data analysis, it is necessary to identify propagation mode of each observed wave which may often be mixed together. In our design of DONET observation system, we took care to help identification of seismic phase by obtaining both ground motion and seafloor pressure in the same location. This is simply achieved by combining seafloor pressure gauges and seismometer in a single observatory package, but care was taken to

Ground motion observations of the 2014 South Napa earthquake

USGS Publications Warehouse

Baltay, Annemarie S.; Boatwright, John

2015-01-01

Using the ground‐motion data compiled and reported by ShakeMap (Wald et al., 2000), we examine the peak ground acceleration (PGA) and peak ground velocity (PGV), as well as the pseudospectral acceleration (PSA) at periods of 0.3, 1.0, and 3.0 s. At the higher frequencies, especially PGA, data recorded at close distances (within ∼20  km) are very consistent with the GMPEs, implying a stress drop for this event similar to the median for California, that is, 5 MPa (Baltay and Hanks, 2014). At all frequencies, the attenuation with distance is stronger than the GMPEs would predict, which suggests the attenuation in the Napa and San Francisco Bay delta region is stronger than the average attenuation in California. The spatial plot of the ground‐motion residuals is positive to the north, in both Napa and Sonoma Valleys, consistent with increases in amplitude expected from both the directivity and basin effects. More interestingly, perhaps, there is strong ground motion to the south in the along‐strike direction, particularly for PSA at 1.0 s. These strongly positive residuals align with an older, Quaternary fault structure associated with the Franklin or Southampton fault, potentially indicating a fault‐zone‐guided wave.

Motion direction discrimination training reduces perceived motion repulsion.

PubMed

Jia, Ke; Li, Sheng

2017-04-01

Participants often exaggerate the perceived angular separation between two simultaneously presented motion stimuli, which is referred to as motion repulsion. The overestimation helps participants differentiate between the two superimposed motion directions, yet it causes the impairment of direction perception. Since direction perception can be refined through perceptual training, we here attempted to investigate whether the training of a direction discrimination task changes the amount of motion repulsion. Our results showed a direction-specific learning effect, which was accompanied by a reduced amount of motion repulsion both for the trained and the untrained directions. The reduction of the motion repulsion disappeared when the participants were trained on a luminance discrimination task (control experiment 1) or a speed discrimination task (control experiment 2), ruling out any possible interpretation in terms of adaptation or training-induced attentional bias. Furthermore, training with a direction discrimination task along a direction 150° away from both directions in the transparent stimulus (control experiment 3) also had little effect on the amount of motion repulsion, ruling out the contribution of task learning. The changed motion repulsion observed in the main experiment was consistent with the prediction of the recurrent model of perceptual learning. Therefore, our findings demonstrate that training in direction discrimination can benefit the precise direction perception of the transparent stimulus and provide new evidence for the recurrent model of perceptual learning.

Main Cause of the Poloidal Plasma Motion Inside a Magnetic Cloud Inferred from Multiple-Spacecraft Observations

NASA Astrophysics Data System (ADS)

Zhao, Ake; Wang, Yuming; Chi, Yutian; Liu, Jiajia; Shen, Chenglong; Liu, Rui

2017-04-01

Although the dynamical evolution of magnetic clouds (MCs) has been one of the foci of interplanetary physics for decades, only few studies focus on the internal properties of large-scale MCs. Recent work by Wang et al. ( J. Geophys. Res. 120, 1543, 2015) suggested the existence of the poloidal plasma motion in MCs. However, the main cause of this motion is not clear. In order to find it, we identify and reconstruct the MC observed by the Solar Terrestrial Relations Observatory (STEREO)-A, Wind, and STEREO-B spacecraft during 19 - 20 November 2007 with the aid of the velocity-modified cylindrical force-free flux-rope model. We analyze the plasma velocity in the plane perpendicular to the MC axis. It is found that there was evident poloidal motion at Wind and STEREO-B, but this was not clear at STEREO-A, which suggests a local cause rather than a global cause for the poloidal plasma motion inside the MC. The rotational directions of the solar wind and MC plasma at the two sides of the MC boundary are found to be consistent, and the values of the rotational speeds of the solar wind and MC plasma at the three spacecraft show a rough correlation. All of these results illustrate that the interaction with ambient solar wind through viscosity might be one of the local causes of the poloidal motion. Additionally, we propose another possible local cause: the existence of a pressure gradient in the MC. The significant difference in the total pressure at the three spacecraft suggests that this speculation is perhaps correct.

Theory of Current-Driven Domain Wall Motion

NASA Astrophysics Data System (ADS)

Tatara, Gen

2004-03-01

Current-induced motion of a domain wall is studied starting from a microscopic Hamiltonian with an exchange interaction between conduction electrons and spins of the wall [1]. With a key observation that the position X and the angle φ0 the wall magnetization forms with the easy plane are the proper collective coordinates to describe its dynamics, it follows straightforwardly that the electric current affects the wall motion in two different ways, in agreement with Berger's pioneering observations[2]. The first is as a force, or momentum transfer, due to the reflection of conduction electrons. This force is proportional to the charge current j and wall resistivity ρ_w, and hence becomes important in thin walls. The other is as a spin torque or spin transfer[3], which is dominant for thick walls where the spin of conduction electron follows the magnetization adiabatically. The motion of a domain wall under a steady current is studied in two limiting cases. In the adiabatic case, we show that even without a pinning force, there is a threshold spin current, j_s^cr∝ K_⊥λ, below which the wall does not move (K_⊥ and λ being the hard-axis magnetic anisotropy and wall thickness, respectively). Below the threshold, the transferred angular momentum is used to shift φ0 and not to the wall motion. The pinning potential V0 affects j_s^cr only if it is very strong, V0 > K_⊥/α, where α is the damping parameter in the Landau-Lifshits-Gilbert equation. Therefore, the critical current for the adiabatic wall does not suffer very much from weak pinning, which is consistent with experimental observations[4]. The wall velocity after depinning is found to be ∝[(j_s/j_s^cr)^2-1]^1/2. In the case of thin wall, driven by a force ∝ ρw j, the critical current density is given by j^cr∝ V_0/ρ_w. In nanocontacts, this is estimated to be ˜ 10^7[A/m^2]. This small critical current would be advantageous for device application. [1] G.Tatara and H.Kohno, cond-mat/0308464

Modeling depth from motion parallax with the motion/pursuit ratio

PubMed Central

Nawrot, Mark; Ratzlaff, Michael; Leonard, Zachary; Stroyan, Keith

2014-01-01

The perception of unambiguous scaled depth from motion parallax relies on both retinal image motion and an extra-retinal pursuit eye movement signal. The motion/pursuit ratio represents a dynamic geometric model linking these two proximal cues to the ratio of depth to viewing distance. An important step in understanding the visual mechanisms serving the perception of depth from motion parallax is to determine the relationship between these stimulus parameters and empirically determined perceived depth magnitude. Observers compared perceived depth magnitude of dynamic motion parallax stimuli to static binocular disparity comparison stimuli at three different viewing distances, in both head-moving and head-stationary conditions. A stereo-viewing system provided ocular separation for stereo stimuli and monocular viewing of parallax stimuli. For each motion parallax stimulus, a point of subjective equality (PSE) was estimated for the amount of binocular disparity that generates the equivalent magnitude of perceived depth from motion parallax. Similar to previous results, perceived depth from motion parallax had significant foreshortening. Head-moving conditions produced even greater foreshortening due to the differences in the compensatory eye movement signal. An empirical version of the motion/pursuit law, termed the empirical motion/pursuit ratio, which models perceived depth magnitude from these stimulus parameters, is proposed. PMID:25339926

Computation of Asteroid Proper Elements on the Grid

NASA Astrophysics Data System (ADS)

Novakovic, B.; Balaz, A.; Knezevic, Z.; Potocnik, M.

2009-12-01

A procedure of gridification of the computation of asteroid proper orbital elements is described. The need to speed up the time consuming computations and make them more efficient is justified by the large increase of observational data expected from the next generation all sky surveys. We give the basic notion of proper elements and of the contemporary theories and methods used to compute them for different populations of objects. Proper elements for nearly 70,000 asteroids are derived since the beginning of use of the Grid infrastructure for the purpose. The average time for the catalogs update is significantly shortened with respect to the time needed with stand-alone workstations. We also present basics of the Grid computing, the concepts of Grid middleware and its Workload management system. The practical steps we undertook to efficiently gridify our application are described in full detail. We present the results of a comprehensive testing of the performance of different Grid sites, and offer some practical conclusions based on the benchmark results and on our experience. Finally, we propose some possibilities for the future work.

Modeling repetitive motions using structured light.

PubMed

Xu, Yi; Aliaga, Daniel G

2010-01-01

Obtaining models of dynamic 3D objects is an important part of content generation for computer graphics. Numerous methods have been extended from static scenarios to model dynamic scenes. If the states or poses of the dynamic object repeat often during a sequence (but not necessarily periodically), we call such a repetitive motion. There are many objects, such as toys, machines, and humans, undergoing repetitive motions. Our key observation is that when a motion-state repeats, we can sample the scene under the same motion state again but using a different set of parameters; thus, providing more information of each motion state. This enables robustly acquiring dense 3D information difficult for objects with repetitive motions using only simple hardware. After the motion sequence, we group temporally disjoint observations of the same motion state together and produce a smooth space-time reconstruction of the scene. Effectively, the dynamic scene modeling problem is converted to a series of static scene reconstructions, which are easier to tackle. The varying sampling parameters can be, for example, structured-light patterns, illumination directions, and viewpoints resulting in different modeling techniques. Based on this observation, we present an image-based motion-state framework and demonstrate our paradigm using either a synchronized or an unsynchronized structured-light acquisition method.

Computer image processing of up-draft flow motion and severe storm formation observed from satellite

NASA Technical Reports Server (NTRS)

Hung, R. J.; Smith, R. E.

1985-01-01

Special rapid-scan satellite visible and infrared observations have been used to study the life cycle of the clouds from the initiation of updraft flow motion in the atmosphere, the condensation of humid air, the formation of clouds, the development of towering cumulus, the penetration of the tropopause, the collapsing of an overshooting turret, and the dissipation of cloud. The infrared image provides an indication of the equivalent blackbody temperature of the observed cloud tops. By referencing the temperature, height and humidity profiles from rawinsonde observations as the background meteorological data for the instability of the air mass to the satellite infrared data sets at different time periods, the development of convective clouds can be studied in detail.

Manikin Laryngoscopy Motion as a Predictor of Patient Intubation Outcomes: A Prospective Observational Study

PubMed Central

Kedarisetty, Suraj; Johnson, Jennifer Moitoza; Glaser, Dale; Delson, Nathan

2018-01-01

Background: The goal of this study was to determine whether motion parameters during laryngoscopy in a manikin differed with experienced operators versus novice trainees and whether motion measurements would predict trainee outcomes when intubating patients. Methods: Motion, force, and duration of laryngoscopy on a manikin were compared in two separate experiments between beginning anesthesiology residents (CA1) and anesthesiologists with more than 24 months of anesthesiology training (CA3 or attendings). In one experiment, CA1 residents were also evaluated for the percentage of their laryngoscope path that followed the route used by attending anesthesiologists. The residents were then observed for patient intubation outcomes for 4 weeks after manikin testing. The relationship between manikin test metrics and patient intubation outcomes was analyzed by multilevel modeling. Results: CA1 residents positioned the laryngoscope blade farther right and with less lift than did experienced anesthesiologists. Endpoint position was 0.6 ± 0.3 cm left of midline for residents (n = 10) versus 2.7 ± 0.3 cm for advanced anesthesiologists (n = 8; P = .0003), and 15.6 ± 0.8 versus 17.7 ± 0.2 cm above the table surface, respectively (P = .033). On average, only 74 ± 6% of the CA1 laryngoscopy trajectory coincided with the Attending Route (P < .001 versus 100%). For each percentage point increase in Attending Route match, residents' odds of intubating a patient's trachea improved by a factor of 1.033 (95% confidence interval [CI] 1.007–1.059, P = .040), and their rate of failed laryngoscopy attempts decreased by a factor of 0.982 (0.969–0.996, P = .045). Discussion: Laryngoscopy motion in manikins may predict which trainees can complete a patient intubation successfully in a few attempts. The assessment could help determine readiness for intubating patients with indirect supervision.

Proper motions of young stars in Chamaeleon. II. New kinematical candidate members of Chamaeleon I and II

NASA Astrophysics Data System (ADS)

López Martí, Belén; Jiménez-Esteban, Francisco; Bayo, Amelia; Barrado, David; Solano, Enrique; Bouy, Hervé; Rodrigo, Carlos

2013-08-01

Context. The Chamaeleon star-forming region has been extensively studied in the last decades. However, most studies have been confined to the densest parts of the clouds. In a previous paper, we analysed the kinematical properties of the spectroscopically confirmed population of the Chamaeleon I and II clouds. Aims: We want to search for new kinematical candidate members to the Chamaeleon I and II moving groups, extending the studied area beyond the clouds, and to characterize these new populations using available information from public databases and catalogues. We also want to check if the populations of the moving groups are confined to the present dark clouds. Methods: Kinematic candidate members were initially selected on the basis of proper motions and colours using the Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4). The SEDs of the objects were constructed using photometry retrieved from the Virtual Observatory and other resources, and fitted to models of stellar photospheres to derive effective temperatures, gravity values, and luminosities. Masses and ages were estimated by comparison with theoretical evolutionary tracks in a Hertzprung-Russell diagram. Objects with ages ≲20 Myr were selected as probable members of the moving groups. Results: We have identified 51 and 14 candidate members to the Chamaeleon I and II moving groups, respectively, of which 17 and 1, respectively, are classified as probable young stars according to the SED analysis. Another object in Chamaeleon I located slightly above the 1 Myr isochrone is classified as a possible young star. All these objects are diskless stars with masses in the range 0.3 ≲ M/M⊙ ≲ 1.4 and ages consistent with those reported for the corresponding confirmed members. They tend to be located at the boundaries of or outside the dark clouds, preferably to the north-east and south-east in the case of Chamaeleon I, and to the north-east in the case of Chamaeleon II. Conclusions: The kinematical

Mold Allergy: Proper Humidifier Care

MedlinePlus

... Training Home Conditions Allergy Allergy Overview Allergy Allergens Mold Allergy Proper Humidifier Care Proper Humidifier Care Make ... neglected humidifier can be a major source of mold and mold spores. Learn how to keep a ...

Teaching Projectile Motion

ERIC Educational Resources Information Center

Summers, M. K.

1977-01-01

Described is a novel approach to the teaching of projectile motion of sixth form level. Students are asked to use an analogue circuit to observe projectile motion and to graph the experimental results. Using knowledge of basic dynamics, students are asked to explain the shape of the curves theoretically. (Author/MA)

New Worlds Observer Formation Control Design Based on the Dynamics of Relative Motion

NASA Technical Reports Server (NTRS)

Luquette, Richard J.

2008-01-01

The New Worlds Observer (NWO) mission is designed for the direct detection and characterization of extrasolar planets. The NWO mission concept employs a two spacecraft leader-follower formation on a trajectory around the Earth/Moon-Sun L(sub 2) Libration Point. The leader spacecraft is baselined as a 4 meter optical telescope. The follower, Starshade spacecraft, is designed to suppress light from a central body star permitting direct detection of a surrounding exoplanetary system. The current design requires a nominal leader-follower separation range of 72 Megameters. NWO poses many challenges including formation control. NWO cycles between three principal control modes during the nominal mission timeline: science (fine pointing), realignment and transition. This paper examines formation control strategies in the context of dynamics of relative motion for two spacecraft operating in the vicinity of the Earth/Moon-Sun L(sub 2)libration point. The paper presents an overview of the equations of relative motion followed by a discussion of each of the control modes. Discussion and analysis characterize control strategies for each of the mission control modes, including requirements, implementation challenges and project fuel budgets.

Determining Our Motion Through the Galaxy

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-12-01

Though we dont notice it from our point of view, were hurtling through space at breakneck speed and one of the contributors to our overall motion through the universe is the Suns revolutionaround the center of our galaxy. A recent study uses an unusual approach to measure the speed of this rotation.Moving While Sitting StillWe know that the Sun zips rapidly around the center of the Milky Way our orbitalspeed is somewhere around250 km/s, or 560,000 mph! Getting a precise measurement of this velocity is useful because we can combine it with the observed proper motion of Sgr A*, the black hole at the center of our galaxy, to determine the distance from us to the center of the Milky Way. This is an important baseline for lots of other measurements.Example particle orbits modeled within the galactic potential. The top panel represents a starwith zero angular momentum, which is scattered into a chaotic orbit after interacting with the galactic nucleus. [Hunt et al. 2016]But how can we measure the Suns revolutionspeed accurately? A team of scientists led by Jason Hunt (Dunlap Institute at University of Toronto, Canada) have suggested a unique approach to pin down this value: look for missing stars in the solar neighborhood.Missing StarsThe stars around us should exhibit a distribution of velocities describing their orbits about the galactic center but those stars with zero angular momentum should have plunged directly into the galactic center long ago. These stars would have been scattered onto chaotic halo orbits after their plunge, resulting in a dearth of stars with zero angular momentum around us today.By looking at the relative speeds of the stars moving around us, then, we should see a dip in the velocity distribution corresponding to the missing zero-angular-momentum stars. By noting the relative velocity at which that dip occurs, we cleverly reveal the negative of our motion around the galactic center.Velocity distribution for stars within 700 pc of the Sun. A dip

Default perception of high-speed motion

PubMed Central

Wexler, Mark; Glennerster, Andrew; Cavanagh, Patrick; Ito, Hiroyuki; Seno, Takeharu

2013-01-01

When human observers are exposed to even slight motion signals followed by brief visual transients—stimuli containing no detectable coherent motion signals—they perceive large and salient illusory jumps. This visually striking effect, which we call “high phi,” challenges well-entrenched assumptions about the perception of motion, namely the minimal-motion principle and the breakdown of coherent motion perception with steps above an upper limit called dmax. Our experiments with transients, such as texture randomization or contrast reversal, show that the magnitude of the jump depends on spatial frequency and transient duration—but not on the speed of the inducing motion signals—and the direction of the jump depends on the duration of the inducer. Jump magnitude is robust across jump directions and different types of transient. In addition, when a texture is actually displaced by a large step beyond the upper step size limit of dmax, a breakdown of coherent motion perception is expected; however, in the presence of an inducer, observers again perceive coherent displacements at or just above dmax. In summary, across a large variety of stimuli, we find that when incoherent motion noise is preceded by a small bias, instead of perceiving little or no motion—as suggested by the minimal-motion principle—observers perceive jumps whose amplitude closely follows their own dmax limits. PMID:23572578

7 CFR 29.112 - Proper light.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for correct...

7 CFR 29.112 - Proper light.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 2 2014-01-01 2014-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for correct...

7 CFR 29.112 - Proper light.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 2 2013-01-01 2013-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for correct...

7 CFR 29.112 - Proper light.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 2 2011-01-01 2011-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for correct...

7 CFR 29.112 - Proper light.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 2 2012-01-01 2012-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for correct...

Reconstructing Plate Motions on Europa with GPlates

NASA Astrophysics Data System (ADS)

Cutler, B. B.; Collins, G. C.; Prockter, L. M.; Patterson, G.; Kattenhorn, S. A.; Rhoden, A.; Cooper, C. M.

2015-12-01

Observations of past plate tectonic - like motions in Europa's icy lithosphere have been reported in previous studies. Quantifying the nature, age, and amount of plate motion is important for geophysical models of Europa's ice shell and for astrobiology, since subsumed pates could drive the flow of nutrients into the subsurface ocean. We have used GPlates software (Williams et al., GSA Today 2012) and a mosaic of regional-resolution Galileo SSI data from orbits E11, E15, E17, and E19 to make interactive reconstructions of both the Northern Falga region (60N, 220W) and the Castalia Macula region (0N, 225W). The advantage of this method is that plate motions are calculated on a sphere, while still maintaining the original Galileo image pieces in their proper geographic locations. Previous work on the Castalia Macula region (Patterson et al. J.Struct.Geol. 2006) and the adjacent Phaidra Linea region (Patterson and Ernst, LPSC 2011) found offsets along spreading boundaries, and then calculated the best fit finite rotations to close those offsets. Though this method is mathematically rigorous and gives a statistical goodness of fit, it is not easy to test multiple hypotheses for candidate piercing points or divisions of candidate plate boundaries. Through the interactive environment, we found that we could better account for observed offsets in this region by breaking it into 32 different plates. Patterson and Ernst broke the Phaidra region into 6 plates which exhibited nonrigid behavior, where our study breaks it into 16 rigid plates. The Northern Falga Regio area is interesting due to the potential for large amounts of subsumption of Europa's icy crust in this location. The previous reconstruction (Kattenhorn and Prockter, Nat.Geosci. 2014) was based on planar geometry, and we have replicated these results using a spherically-based reconstruction. We will present the plate maps and reconstructions for both of these regions, along with the best fit rotation poles.

Direct observation of X-ray induced atomic motion using scanning tunneling microscope combined with synchrotron radiation.

PubMed

Saito, Akira; Tanaka, Takehiro; Takagi, Yasumasa; Hosokawa, Hiromasa; Notsu, Hiroshi; Ohzeki, Gozo; Tanaka, Yoshihito; Kohmura, Yoshiki; Akai-Kasaya, Megumi; Ishikawa, Tetsuya; Kuwahara, Yuji; Kikuta, Seishi; Aono, Masakazu

2011-04-01

X-ray induced atomic motion on a Ge(111)-c(2 x 8) clean surface at room temperature was directly observed with atomic resolution using a synchrotron radiation (SR)-based scanning tunneling microscope (STM) system under ultra high vacuum condition. The atomic motion was visualized as a tracking image by developing a method to merge the STM images before and after X-ray irradiation. Using the tracking image, the atomic mobility was found to be strongly affected by defects on the surface, but was not dependent on the incident X-ray energy, although it was clearly dependent on the photon density. The atomic motion can be attributed to surface diffusion, which might not be due to core-excitation accompanied with electronic transition, but a thermal effect by X-ray irradiation. The crystal surface structure was possible to break even at a lower photon density than the conventionally known barrier. These results can alert X-ray studies in the near future about sample damage during measurements, while suggesting the possibility of new applications. Also the obtained results show a new availability of the in-situ SR-STM system.

Using Simulated Ground Motions to Constrain Near-Source Ground Motion Prediction Equations in Areas Experiencing Induced Seismicity

NASA Astrophysics Data System (ADS)

Bydlon, S. A.; Dunham, E. M.

2016-12-01

Recent increases in seismic activity in historically quiescent areas such as Oklahoma, Texas, and Arkansas, including large, potentially induced events such as the 2011 Mw 5.6 Prague, OK, earthquake, have spurred the need for investigation into expected ground motions associated with these seismic sources. The neoteric nature of this seismicity increase corresponds to a scarcity of ground motion recordings within 50 km of earthquakes Mw 3.0 and greater, with increasing scarcity at larger magnitudes. Gathering additional near-source ground motion data will help better constraints on regional ground motion prediction equations (GMPEs) and will happen over time, but this leaves open the possibility of damaging earthquakes occurring before potential ground shaking and seismic hazard in these areas are properly understood. To aid the effort of constraining near-source GMPEs associated with induced seismicity, we integrate synthetic ground motion data from simulated earthquakes into the process. Using the dynamic rupture and seismic wave propagation code waveqlab3d, we perform verification and validation exercises intended to establish confidence in simulated ground motions for use in constraining GMPEs. We verify the accuracy of our ground motion simulator by performing the PEER/SCEC layer-over-halfspace comparison problem LOH.1 Validation exercises to ensure that we are synthesizing realistic ground motion data include comparisons to recorded ground motions for specific earthquakes in target areas of Oklahoma between Mw 3.0 and 4.0. Using a 3D velocity structure that includes a 1D structure with additional small-scale heterogeneity, the properties of which are based on well-log data from Oklahoma, we perform ground motion simulations of small (Mw 3.0 - 4.0) earthquakes using point moment tensor sources. We use the resulting synthetic ground motion data to develop GMPEs for small earthquakes in Oklahoma. Preliminary results indicate that ground motions can be amplified

Sustained attention to objects' motion sharpens position representations: Attention to changing position and attention to motion are distinct.

PubMed

Howard, Christina J; Rollings, Victoria; Hardie, Amy

2017-06-01

In tasks where people monitor moving objects, such the multiple object tracking task (MOT), observers attempt to keep track of targets as they move amongst distracters. The literature is mixed as to whether observers make use of motion information to facilitate performance. We sought to address this by two means: first by superimposing arrows on objects which varied in their informativeness about motion direction and second by asking observers to attend to motion direction. Using a position monitoring task, we calculated mean error magnitudes as a measure of the precision with which target positions are represented. We also calculated perceptual lags versus extrapolated reports, which are the times at which positions of targets best match position reports. We find that the presence of motion information in the form of superimposed arrows made no difference to position report precision nor perceptual lag. However, when we explicitly instructed observers to attend to motion, we saw facilitatory effects on position reports and in some cases reports that best matched extrapolated rather than lagging positions for small set sizes. The results indicate that attention to changing positions does not automatically recruit attention to motion, showing a dissociation between sustained attention to changing positions and attention to motion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Contrasting accounts of direction and shape perception in short-range motion: Counterchange compared with motion energy detection.

PubMed

Norman, Joseph; Hock, Howard; Schöner, Gregor

2014-07-01

It has long been thought (e.g., Cavanagh & Mather, 1989) that first-order motion-energy extraction via space-time comparator-type models (e.g., the elaborated Reichardt detector) is sufficient to account for human performance in the short-range motion paradigm (Braddick, 1974), including the perception of reverse-phi motion when the luminance polarity of the visual elements is inverted during successive frames. Human observers' ability to discriminate motion direction and use coherent motion information to segregate a region of a random cinematogram and determine its shape was tested; they performed better in the same-, as compared with the inverted-, polarity condition. Computational analyses of short-range motion perception based on the elaborated Reichardt motion energy detector (van Santen & Sperling, 1985) predict, incorrectly, that symmetrical results will be obtained for the same- and inverted-polarity conditions. In contrast, the counterchange detector (Hock, Schöner, & Gilroy, 2009) predicts an asymmetry quite similar to that of human observers in both motion direction and shape discrimination. The further advantage of counterchange, as compared with motion energy, detection for the perception of spatial shape- and depth-from-motion is discussed.

The effect of center-of-mass motion on photon statistics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yang; Zhang, Jun; Wu, Shao-xiong

2015-10-15

We analyze the photon statistics of a weakly driven cavity quantum electrodynamics system and discuss the effects of photon blockade and photon-induced tunneling by effectively utilizing instead of avoiding the center-of-mass motion of a two-level atom trapped in the cavity. With the resonant interaction between atom, photon and phonon, it is shown that the bunching and anti-bunching of photons can occur with properly driving frequency. Our study shows the influence of the imperfect cooling of atom on the blockade and provides an attempt to take advantage of the center-of-mass motion.

Observed and simulated ground motions in the San Bernardino basin region for the Hector Mine, California, earthquake

USGS Publications Warehouse

Graves, R.W.; Wald, D.J.

2004-01-01

surface wave energy is confined to the region north of this structure, consistent with the observations. The SCEC version 3 model, lacking the basin geometry complexity present in the other two models, fails to provide a satisfactory match to the characteristics of the observed motions. Our study demonstrates the importance of using detailed and accurate basin geometry for predicting ground motions and also highlights the utility of integrating geological, geophysical, and seismological observations in the development and validation of 3D velocity models.

The lucky image-motion prediction for simple scene observation based soft-sensor technology

NASA Astrophysics Data System (ADS)

Li, Yan; Su, Yun; Hu, Bin

2015-08-01

High resolution is important to earth remote sensors, while the vibration of the platforms of the remote sensors is a major factor restricting high resolution imaging. The image-motion prediction and real-time compensation are key technologies to solve this problem. For the reason that the traditional autocorrelation image algorithm cannot meet the demand for the simple scene image stabilization, this paper proposes to utilize soft-sensor technology in image-motion prediction, and focus on the research of algorithm optimization in imaging image-motion prediction. Simulations results indicate that the improving lucky image-motion stabilization algorithm combining the Back Propagation Network (BP NN) and support vector machine (SVM) is the most suitable for the simple scene image stabilization. The relative error of the image-motion prediction based the soft-sensor technology is below 5%, the training computing speed of the mathematical predication model is as fast as the real-time image stabilization in aerial photography.

Fractional Brownian motion and motion governed by the fractional Langevin equation in confined geometries.

PubMed

Jeon, Jae-Hyung; Metzler, Ralf

2010-02-01

Motivated by subdiffusive motion of biomolecules observed in living cells, we study the stochastic properties of a non-Brownian particle whose motion is governed by either fractional Brownian motion or the fractional Langevin equation and restricted to a finite domain. We investigate by analytic calculations and simulations how time-averaged observables (e.g., the time-averaged mean-squared displacement and displacement correlation) are affected by spatial confinement and dimensionality. In particular, we study the degree of weak ergodicity breaking and scatter between different single trajectories for this confined motion in the subdiffusive domain. The general trend is that deviations from ergodicity are decreased with decreasing size of the movement volume and with increasing dimensionality. We define the displacement correlation function and find that this quantity shows distinct features for fractional Brownian motion, fractional Langevin equation, and continuous time subdiffusion, such that it appears an efficient measure to distinguish these different processes based on single-particle trajectory data.

Proper Acknowledgment?

ERIC Educational Resources Information Center

East, Julianne

2005-01-01

The concern in Australian universities about the prevalence of plagiarism has led to the development of policies about academic integrity and in turn focused attention on the need to inform students about how to avoid plagiarism and how to properly acknowledge. Teaching students how to avoid plagiarism can appear to be straightforward if based on…

Proper Brushing

MedlinePlus

... bristles along the gumline at a 45-degree angle. Bristles should contact both the tooth surface and the gumline. Gently ... A rolling motion is when the brush makes contact with the gumline and ... a 45-degree angle with bristles contacting the tooth surface and gumline. ...

Simulating intrafraction prostate motion with a random walk model.

PubMed

Pommer, Tobias; Oh, Jung Hun; Munck Af Rosenschöld, Per; Deasy, Joseph O

2017-01-01

Prostate motion during radiation therapy (ie, intrafraction motion) can cause unwanted loss of radiation dose to the prostate and increased dose to the surrounding organs at risk. A compact but general statistical description of this motion could be useful for simulation of radiation therapy delivery or margin calculations. We investigated whether prostate motion could be modeled with a random walk model. Prostate motion recorded during 548 radiation therapy fractions in 17 patients was analyzed and used for input in a random walk prostate motion model. The recorded motion was categorized on the basis of whether any transient excursions (ie, rapid prostate motion in the anterior and superior direction followed by a return) occurred in the trace and transient motion. This was separately modeled as a large step in the anterior/superior direction followed by a returning large step. Random walk simulations were conducted with and without added artificial transient motion using either motion data from all observed traces or only traces without transient excursions as model input, respectively. A general estimate of motion was derived with reasonable agreement between simulated and observed traces, especially during the first 5 minutes of the excursion-free simulations. Simulated and observed diffusion coefficients agreed within 0.03, 0.2 and 0.3 mm 2 /min in the left/right, superior/inferior, and anterior/posterior directions, respectively. A rapid increase in variance at the start of observed traces was difficult to reproduce and seemed to represent the patient's need to adjust before treatment. This could be estimated somewhat using artificial transient motion. Random walk modeling is feasible and recreated the characteristics of the observed prostate motion. Introducing artificial transient motion did not improve the overall agreement, although the first 30 seconds of the traces were better reproduced. The model provides a simple estimate of prostate motion during

Three-dimensional scapular kinematics during the throwing motion.

PubMed

Meyer, Kristin E; Saether, Erin E; Soiney, Emily K; Shebeck, Meegan S; Paddock, Keith L; Ludewig, Paula M

2008-02-01

Proper scapular motion is crucial for normal shoulder mechanics. Scapular motion affects glenohumeral joint function during throwing, yet little is known about this dynamic activity. Asymptomatic subjects (10 male and 10 female), ages 21 to 45, were analyzed. Electromagnetic surface sensors on the sternum, acromion, and humerus were used to collect 3-D motion data during three trials of low-velocity throwing. Scapular angular position data were described or five predetermined events throughout the throw corresponding with classic descriptions of throwing phases, and trial-to-trial reliability was determined. ANOVA compared scapular angles across events. Subjects demonstrated good to excellent reliability between trials of the throw (ICC 0.74-0.98). The scapula demonstrated a pattern of external rotation, upward rotation (peak of approx. 40 degrees), and poster humeral horizontal abduction. During the arm acceleration phase, the scapula moved toward greater internal rotation and began anteriorly tilting. At maximum humeral internal rotation, the scapula ended in internal rotation (55 degrees), upward rotation (20 degrees), and anterior tilting (3 degrees). Significant differences in scapular position (p<0.05) were identified across the throwing motion. Scapular data identify events in the throwing motion in which throwers may be more susceptible to shoulder pathologies related to abnormal scapular kinematics.

Visual stimuli induced by self-motion and object-motion modify odour-guided flight of male moths (Manduca sexta L.).

PubMed

Verspui, Remko; Gray, John R

2009-10-01

Animals rely on multimodal sensory integration for proper orientation within their environment. For example, odour-guided behaviours often require appropriate integration of concurrent visual cues. To gain a further understanding of mechanisms underlying sensory integration in odour-guided behaviour, our study examined the effects of visual stimuli induced by self-motion and object-motion on odour-guided flight in male M. sexta. By placing stationary objects (pillars) on either side of a female pheromone plume, moths produced self-induced visual motion during odour-guided flight. These flights showed a reduction in both ground and flight speeds and inter-turn interval when compared with flight tracks without stationary objects. Presentation of an approaching 20 cm disc, to simulate object-motion, resulted in interrupted odour-guided flight and changes in flight direction away from the pheromone source. Modifications of odour-guided flight behaviour in the presence of stationary objects suggest that visual information, in conjunction with olfactory cues, can be used to control the rate of counter-turning. We suggest that the behavioural responses to visual stimuli induced by object-motion indicate the presence of a neural circuit that relays visual information to initiate escape responses. These behavioural responses also suggest the presence of a sensory conflict requiring a trade-off between olfactory and visually driven behaviours. The mechanisms underlying olfactory and visual integration are discussed in the context of these behavioural responses.

Proper Names: Reference and Attribution

ERIC Educational Resources Information Center

Maumus, Michael Fletcher

2012-01-01

In the wake of Saul Kripke's landmark "Naming and Necessity," the claim that proper names are directly referential expressions devoid of descriptive content has come to verge on philosophical commonplace. Nevertheless, the return to a purely referential semantics for proper names has coincided with the resurgence of the very puzzles…

Design and verification of a simple 3D dynamic model of speed skating which mimics observed forces and motions.

PubMed

van der Kruk, E; Veeger, H E J; van der Helm, F C T; Schwab, A L

2017-11-07

Advice about the optimal coordination pattern for an individual speed skater, could be addressed by simulation and optimization of a biomechanical speed skating model. But before getting to this optimization approach one needs a model that can reasonably match observed behaviour. Therefore, the objective of this study is to present a verified three dimensional inverse skater model with minimal complexity, which models the speed skating motion on the straights. The model simulates the upper body transverse translation of the skater together with the forces exerted by the skates on the ice. The input of the model is the changing distance between the upper body and the skate, referred to as the leg extension (Euclidean distance in 3D space). Verification shows that the model mimics the observed forces and motions well. The model is most accurate for the position and velocity estimation (respectively 1.2% and 2.9% maximum residuals) and least accurate for the force estimations (underestimation of 4.5-10%). The model can be used to further investigate variables in the skating motion. For this, the input of the model, the leg extension, can be optimized to obtain a maximal forward velocity of the upper body. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Motion cues that make an impression: Predicting perceived personality by minimal motion information.

PubMed

Koppensteiner, Markus

2013-11-01

The current study presents a methodology to analyze first impressions on the basis of minimal motion information. In order to test the applicability of the approach brief silent video clips of 40 speakers were presented to independent observers (i.e., did not know speakers) who rated them on measures of the Big Five personality traits. The body movements of the speakers were then captured by placing landmarks on the speakers' forehead, one shoulder and the hands. Analysis revealed that observers ascribe extraversion to variations in the speakers' overall activity, emotional stability to the movements' relative velocity, and variation in motion direction to openness. Although ratings of openness and conscientiousness were related to biographical data of the speakers (i.e., measures of career progress), measures of body motion failed to provide similar results. In conclusion, analysis of motion behavior might be done on the basis of a small set of landmarks that seem to capture important parts of relevant nonverbal information.

Empirical relationships between instrumental ground motions and observed intensities for two great Chilean subduction zone earthquakes

NASA Astrophysics Data System (ADS)

Cilia, M. G.; Baker, L. M.

2015-12-01

We determine empirical relationships between instrumental peak ground motions and observed intensities for two great Chilean subduction earthquakes: the 2010 Mw8.8 Maule earthquake and the 2014 Mw8.2 Iquique earthquake. Both occurred immediately offshore on the primary plate boundary interface between the Nazca and South America plates. They are among the largest earthquakes to be instrumentally recorded; the 2010 Maule event is the second largest earthquake to produce strong motion recordings. Ground motion to intensity conversion equations (GMICEs) are used to reconstruct the distribution of shaking for historical earthquakes by using intensities estimated from contemporary accounts. Most great (M>8) earthquakes, like these, occur within subduction zones, yet few GMICEs exist for subduction earthquakes. It is unclear whether GMICEs developed for active crustal regions, such as California, can be scaled up to the large M of subduction zone events, or if new data sets must be analyzed to develop separate subduction GMICEs. To address this question, we pair instrumental peak ground motions, both acceleration (PGA) and velocity (PGV), with intensities derived from onsite surveys of earthquake damage made in the weeks after the events and internet-derived felt reports. We fit a linear predictive equation between the geometric mean of the maximum PGA or PGV of the two horizontal components and intensity, using linear least squares. We use a weighting scheme to express the uncertainty of the pairings based on a station's proximity to the nearest intensity observation. The intensity data derived from the onsite surveys is a complete, high-quality investigation of the earthquake damage. We perform the computations using both the survey data and community decimal intensities (CDI) calculated from felt reports volunteered by citizens (USGS "Did You Feel It", DYFI) and compare the results. We compare the GMICEs we developed to the most widely used GMICEs from California and

Inducing Tropical Cyclones to Undergo Brownian Motion

NASA Astrophysics Data System (ADS)

Hodyss, D.; McLay, J.; Moskaitis, J.; Serra, E.

2014-12-01

Stochastic parameterization has become commonplace in numerical weather prediction (NWP) models used for probabilistic prediction. Here, a specific stochastic parameterization will be related to the theory of stochastic differential equations and shown to be affected strongly by the choice of stochastic calculus. From an NWP perspective our focus will be on ameliorating a common trait of the ensemble distributions of tropical cyclone (TC) tracks (or position), namely that they generally contain a bias and an underestimate of the variance. With this trait in mind we present a stochastic track variance inflation parameterization. This parameterization makes use of a properly constructed stochastic advection term that follows a TC and induces its position to undergo Brownian motion. A central characteristic of Brownian motion is that its variance increases with time, which allows for an effective inflation of an ensemble's TC track variance. Using this stochastic parameterization we present a comparison of the behavior of TCs from the perspective of the stochastic calculi of Itô and Stratonovich within an operational NWP model. The central difference between these two perspectives as pertains to TCs is shown to be properly predicted by the stochastic calculus and the Itô correction. In the cases presented here these differences will manifest as overly intense TCs, which, depending on the strength of the forcing, could lead to problems with numerical stability and physical realism.

Oil Motion Control by an Extra Pinning Structure in Electro-Fluidic Display.

PubMed

Dou, Yingying; Tang, Biao; Groenewold, Jan; Li, Fahong; Yue, Qiao; Zhou, Rui; Li, Hui; Shui, Lingling; Henzen, Alex; Zhou, Guofu

2018-04-06

Oil motion control is the key for the optical performance of electro-fluidic displays (EFD). In this paper, we introduced an extra pinning structure (EPS) into the EFD pixel to control the oil motion inside for the first time. The pinning structure canbe fabricated together with the pixel wall by a one-step lithography process. The effect of the relative location of the EPS in pixels on the oil motion was studied by a series of optoelectronic measurements. EPS showed good control of oil rupture position. The properly located EPS effectively guided the oil contraction direction, significantly accelerated switching on process, and suppressed oil overflow, without declining in aperture ratio. An asymmetrically designed EPS off the diagonal is recommended. This study provides a novel and facile way for oil motion control within an EFD pixel in both direction and timescale.

Vertical motions in the Uranian atmosphere - An analysis of radio observations

NASA Technical Reports Server (NTRS)

Hofstadter, Mark D.; Berge, Glenn L.; Muhleman, Duane O.

1990-01-01

The present, 6-cm radio map of Uranus indicates latitudinal features which may be due to vertical motions of the atmosphere. It appears in light of Voyager IR measurements as well as previously obtained radio data that these large-scale vertical motions, which have not undergone significant changes over the course of 8 years, extend from the 0.1- to the 45-bar levels; this span corresponds to a height of the order of 250 km. The latitudinal structures are believed to be primarily caused by horizontal variations of absorber abundances.

Tracking brain motion during the cardiac cycle using spiral cine-DENSE MRI

PubMed Central

Zhong, Xiaodong; Meyer, Craig H.; Schlesinger, David J.; Sheehan, Jason P.; Epstein, Frederick H.; Larner, James M.; Benedict, Stanley H.; Read, Paul W.; Sheng, Ke; Cai, Jing

2009-01-01

Cardiac-synchronized brain motion is well documented, but the accurate measurement of such motion on the pixel-by-pixel basis has been hampered by the lack of proper imaging technique. In this article, the authors present the implementation of an autotracking spiral cine displacement-encoded stimulation echo (DENSE) magnetic resonance imaging (MRI) technique for the measurement of pulsatile brain motion during the cardiac cycle. Displacement-encoded dynamic MR images of three healthy volunteers were acquired throughout the cardiac cycle using the spiral cine-DENSE pulse sequence gated to the R wave of an electrocardiogram. Pixelwise Lagrangian displacement maps were computed, and 2D displacement as a function of time was determined for selected regions of interests. Different intracranial structures exhibited characteristic motion amplitude, direction, and pattern throughout the cardiac cycle. Time-resolved displacement curves revealed the pathway of pulsatile motion from brain stem to peripheral brain lobes. These preliminary results demonstrated that the spiral cine-DENSE MRI technique can be used to measure cardiac-synchronized pulsatile brain motion on the pixel-by-pixel basis with high temporal∕spatial resolution and sensitivity. PMID:19746774

VizieR Online Data Catalog: Proper motions and photometry for members of Cha I (Esplin+, 2017)

NASA Astrophysics Data System (ADS)

Esplin, T. L.; Luhman, K. L.; Faherty, J. K.; Mamajek, E. E.; Bochanski, J. J.

2017-10-01

We have compiled a catalog of the previously known members of Cha I. We began with the census from Luhman 2008 (Cat. J/ApJ/675/1375). we adopt ChaJ11100159-7738052 as a previously known member, which was presented in Luhman 2007 (Cat. J/ApJS/173/104) as a possible field M9-L1 dwarf. We also include in our census the M9 companion to CT Cha (Schmidt et al. 2008A&A...491..311S) and five new M4 members from Frasca et al. 2015 (Cat. J/A+A/575/A4) and Sacco et al. 2017 (Cat. J/A+A/601/A97): 2MASSJ10575375-7724495, 2MASSJ10563146-7618334, 2MASSJ11213079-7633351, 2MASSJ11130450-7534369, and 2MASSJ11090915-7553477. We list the 244 previously known members and the 6 new members from this study in Table1. Luhman et al. (2005ApJ...635L..93L) obtained images of a 13.3'*16.7' area of the southern subcluster in Cha I with the Wide Field Camera (WFC) aperture of the Advanced Camera for Surveys (ACS) on board HST. The observations were performed on 2004 August 21 and 2005 February 16 with the F775W and F850LP filters. To measure proper motions for sources detected in those data, we repeated those observations in the F850LP filter on 2009 August 20 and 2011 February 13 through program 11695. Portions of Cha I have been imaged at several epochs with the Infrared Array Camera (IRAC) on Spitzer. Those observations occurred during both the cryogenic and post-cryogenic phases of the mission. The cryogenic phase began at launch in 2003 August and continued until 2009 May, when the liquid helium was depleted. During that time, IRAC operated with four 256*256 arrays that collected images in broadband filters at 3.6, 4.5, 5.8, and 8.0μm, which are denoted as [3.6], [4.5], [5.8], and [8.0]. For each array, the plate scale was 1.2''/pixel and the field of view (FOV) was 5.2'*5.2'. Point sources within the images have a FWHM of 1.6''-1.9'' for [3.6]-[8.0]. We compiled photometry from previous surveys for low-mass members of Cha I and publicly available catalogs, which consist of F775W and F850

Sunspot observations from the SOUP instrument on Spacelab 2

NASA Astrophysics Data System (ADS)

Shine, R. A.; Title, A. M.; Tarbell, T. D.; Acton, L.; Duncan, D.; Ferguson, S. H.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren, R.

1987-09-01

A series of white light images obtained by the SOUP instrument on Spacelab 2 of active region 4682 on August 5, 1985 were analyzed in the area containing sunspots. Although the umbra of the spot is underexposed, the film is well exposed in the penumbral regions. These data were digitally processed to remove noise and to separate p-mode oscillations from low velocity material motions. The results of this preliminary investigation include: (1) proper motion measurements of a radial outflow in the photospheric granulation pattern just outside the penumbra; (2) discovery of occasional bright structures (streakers) that appear to be ejected outward from the penumbra; (3) broad dark clouds moving outward in the penumbra in addition to the well known bright penumbral grains moving inward; (4) apparent extensions and contractions of penumbral filaments over the photosphere; and (5) observation of a faint bubble or loop-like structure which seems to expand from two bright penumbral filaments into the photosphere.

Sunspot observations from the SOUP instrument on Spacelab 2

NASA Technical Reports Server (NTRS)

Shine, R. A.; Title, A. M.; Tarbell, T. D.; Acton, L.; Duncan, D.; Ferguson, S. H.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren, R.

1987-01-01

A series of white light images obtained by the SOUP instrument on Spacelab 2 of active region 4682 on August 5, 1985 were analyzed in the area containing sunspots. Although the umbra of the spot is underexposed, the film is well exposed in the penumbral regions. These data were digitally processed to remove noise and to separate p-mode oscillations from low velocity material motions. The results of this preliminary investigation include: (1) proper motion measurements of a radial outflow in the photospheric granulation pattern just outside the penumbra; (2) discovery of occasional bright structures (streakers) that appear to be ejected outward from the penumbra; (3) broad dark clouds moving outward in the penumbra in addition to the well known bright penumbral grains moving inward; (4) apparent extensions and contractions of penumbral filaments over the photosphere; and (5) observation of a faint bubble or loop-like structure which seems to expand from two bright penumbral filaments into the photosphere.

Spectroscopic observations of cool degenerate star candidates

NASA Technical Reports Server (NTRS)

Hintzen, P.

1986-01-01

Spectroscopic observations are reported for 23 Luyten Half-Second degenerate star candidates and for 13 Luyten-Palomar common proper-motion pairs containing possible degenerate star components. Twenty-five degenerate stars are identified, 20 of which lack previous spectroscopy. Most of these stars are cool - Luyten color class g or later. One star, LP 77-57, shows broad continuum depressions similar to those in LHS 1126, which Liebert and Dahn attributed to pressure-shifted C2. A second degenerate star, LHS 290, exhibits apparent strong Swan bands which are blueshifted about 75 A. Further observations, including polarimetry and photometry, are required to appraise the spectroscopic peculiarities of these stars. Finally, five cool, sharp-lined DA white dwarfs have been observed to detect lines of metals and to determine line strengths. None of these DAs show signs of Mg b or the G band, and four show no evidence of Ca II K. The attempt to detect Ca MI in the fifth star, G199-71, was inconclusive.

Geocenter Motion Derived from the JTRF2014 Combination

NASA Astrophysics Data System (ADS)

Abbondanza, C.; Chin, T. M.; Gross, R. S.; Heflin, M. B.; Parker, J. W.; van Dam, T. M.; Wu, X.

2016-12-01

JTRF2014 represents the JPL Terrestrial Reference Frame (TRF) recently obtained as a result of the combination of the space-geodetic reprocessed inputs to the ITRF2014. Based upon a Kalman filter and smoother approach, JTRF2014 assimilates station positions and Earth-Orientation Parameters (EOPs) from GNSS, VLBI, SLR and DORIS and combine them through local tie measurements. JTRF is in its essence a time-series based TRF. In the JTRF2014 the dynamical evolution of the station positions is formulated by introducing linear and seasonal terms (annual and semi-annual periodic modes). Non-secular and non-seasonal motions of the geodetic sites are included in the smoothed time series by properly defining the station position process noise whose variance is characterized by analyzing station displacements induced by temporal changes of planetary fluid masses (atmosphere, oceans and continental surface water). With its station position time series output at a weekly resolution, JTRF2014 materializes a sub-secular frame whose origin is at the quasi-instantaneous Center of Mass (CM) as sensed by SLR. Both SLR and VLBI contribute to the scale of the combined frame. The sub-secular nature of the frame allows the users to directly access the quasi-instantaneous geocenter and scale information. Unlike standard combined TRF products which only give access to the secular component of the CM-CN motions, JTRF2014 is able to preserve -in addition to the long-term- the seasonal, non-seasonal and non-secular components of the geocenter motion. In the JTRF2014 assimilation scheme, local tie measurements are used to transfer the geocenter information from SLR to the space-geodetic techniques which are either insensitive to CM (VLBI) or whose geocenter motion is poorly determined (GNSS and DORIS). Properly tied to the CM frame through local ties and co-motion constraints, GNSS, VLBI and DORIS contribute to improve the SLR network geometry. In this paper, the determination of the weekly

Deep HST Imaging in 47 Tucanae: A Global Dynamical Model

NASA Astrophysics Data System (ADS)

Heyl, J.; Caiazzo, I.; Richer, H.; Anderson, J.; Kalirai, J.; Parada, J.

2017-12-01

Multi-epoch observations with the Advanced Camera Survey and WFC3 on the Hubble Space Telescope provide a unique and comprehensive probe of stellar dynamics within 47 Tucanae. We confront analytic models of the globular cluster with the observed stellar proper motions that probe along the main sequence from just above 0.8-0.1M ⊙ as well as white dwarfs younger than 1 Gyr. One field lies just beyond the half-light radius where dynamical models (e.g., lowered Maxwellian distributions) make robust predictions for the stellar proper motions. The observed proper motions in this outer field show evidence for anisotropy in the velocity distribution as well as skewness; the latter is evidence of rotation. The measured velocity dispersions and surface brightness distributions agree in detail with a rotating anisotropic model of the stellar distribution function with mild dependence of the proper-motion dispersion on mass. However, the best-fitting models underpredict the rotation and skewness of the stellar velocities. In the second field, centered on the core of the cluster, the mass segregation in proper motion is much stronger. Nevertheless the model developed in the outer field can be extended inward by taking this mass segregation into account in a heuristic fashion. The proper motions of the main-sequence stars yield a mass estimate of the cluster of 1.31+/- 0.02× {10}6{M}⊙ at a distance of 4.7 kpc. By comparing the proper motions of a sample of giant and subgiant stars with the observed radial velocities we estimate the distance to the cluster kinematically to be 4.29 ± 0.47 kpc.

Moving object detection using dynamic motion modelling from UAV aerial images.

PubMed

Saif, A F M Saifuddin; Prabuwono, Anton Satria; Mahayuddin, Zainal Rasyid

2014-01-01

Motion analysis based moving object detection from UAV aerial image is still an unsolved issue due to inconsideration of proper motion estimation. Existing moving object detection approaches from UAV aerial images did not deal with motion based pixel intensity measurement to detect moving object robustly. Besides current research on moving object detection from UAV aerial images mostly depends on either frame difference or segmentation approach separately. There are two main purposes for this research: firstly to develop a new motion model called DMM (dynamic motion model) and secondly to apply the proposed segmentation approach SUED (segmentation using edge based dilation) using frame difference embedded together with DMM model. The proposed DMM model provides effective search windows based on the highest pixel intensity to segment only specific area for moving object rather than searching the whole area of the frame using SUED. At each stage of the proposed scheme, experimental fusion of the DMM and SUED produces extracted moving objects faithfully. Experimental result reveals that the proposed DMM and SUED have successfully demonstrated the validity of the proposed methodology.

Simulating Astro-H Observations of Sloshing Gas Motions in the Cores of Galaxy Clusters

NASA Astrophysics Data System (ADS)

ZuHone, J. A.; Miller, E. D.; Simionescu, A.; Bautz, M. W.

2016-04-01

Astro-H will be the first X-ray observatory to employ a high-resolution microcalorimeter, capable of measuring the shift and width of individual spectral lines to the precision necessary for estimating the velocity of the diffuse plasma in galaxy clusters. This new capability is expected to bring significant progress in understanding the dynamics, and therefore the physics, of the intracluster medium. However, because this plasma is optically thin, projection effects will be an important complicating factor in interpreting future Astro-H measurements. To study these effects in detail, we performed an analysis of the velocity field from simulations of a galaxy cluster experiencing gas sloshing and generated synthetic X-ray spectra, convolved with model Astro-H Soft X-ray Spectrometer (SXS) responses. We find that the sloshing motions produce velocity signatures that will be observable by Astro-H in nearby clusters: the shifting of the line centroid produced by the fast-moving cold gas underneath the front surface, and line broadening produced by the smooth variation of this motion along the line of sight. The line shapes arising from inviscid or strongly viscous simulations are very similar, indicating that placing constraints on the gas viscosity from these measurements will be difficult. Our spectroscopic analysis demonstrates that, for adequate exposures, Astro-H will be able to recover the first two moments of the velocity distribution of these motions accurately, and in some cases multiple velocity components may be discerned. The simulations also confirm the importance of accurate treatment of point-spread function scattering in the interpretation of Astro-H/SXS spectra of cluster plasmas.

Pilot study on real-time motion detection in UAS video data by human observer and image exploitation algorithm

NASA Astrophysics Data System (ADS)

Hild, Jutta; Krüger, Wolfgang; Brüstle, Stefan; Trantelle, Patrick; Unmüßig, Gabriel; Voit, Michael; Heinze, Norbert; Peinsipp-Byma, Elisabeth; Beyerer, Jürgen

2017-05-01

Real-time motion video analysis is a challenging and exhausting task for the human observer, particularly in safety and security critical domains. Hence, customized video analysis systems providing functions for the analysis of subtasks like motion detection or target tracking are welcome. While such automated algorithms relieve the human operators from performing basic subtasks, they impose additional interaction duties on them. Prior work shows that, e.g., for interaction with target tracking algorithms, a gaze-enhanced user interface is beneficial. In this contribution, we present an investigation on interaction with an independent motion detection (IDM) algorithm. Besides identifying an appropriate interaction technique for the user interface - again, we compare gaze-based and traditional mouse-based interaction - we focus on the benefit an IDM algorithm might provide for an UAS video analyst. In a pilot study, we exposed ten subjects to the task of moving target detection in UAS video data twice, once performing with automatic support, once performing without it. We compare the two conditions considering performance in terms of effectiveness (correct target selections). Additionally, we report perceived workload (measured using the NASA-TLX questionnaire) and user satisfaction (measured using the ISO 9241-411 questionnaire). The results show that a combination of gaze input and automated IDM algorithm provides valuable support for the human observer, increasing the number of correct target selections up to 62% and reducing workload at the same time.

Counter-current motion in counter-current chromatography.

PubMed

Ito, Yoichiro

2014-12-12

After the CCC2012 meeting, I have received an e-mail regarding the terminology of "Countercurrent Chromatography". It stated that the term "Countercurrent" is a misnomer, because its stationary phase is motionless in the column and that the method should be renamed as liquid-liquid separations or centrifugal separations. However, it was found that these names are already used for various other techniques as found via Google search. The term "Countercurrent Chromatography" was originally made after two preparative methods of Countercurrent distribution and liquid Chromatography, both having no countercurrent motion in the column. However, it is surprising to find that this F1 hybrid method "Countercurrent Chromatography" can clearly exhibit countercurrent motion within the separation column in both hydrodynamic and hydrostatic equilibrium systems. This justifies that "Countercurrent Chromatography" is a proper term for this chromatographic method. Published by Elsevier B.V.

Evidence for auditory-visual processing specific to biological motion.

PubMed

Wuerger, Sophie M; Crocker-Buque, Alexander; Meyer, Georg F

2012-01-01

Biological motion is usually associated with highly correlated sensory signals from more than one modality: an approaching human walker will not only have a visual representation, namely an increase in the retinal size of the walker's image, but also a synchronous auditory signal since the walker's footsteps will grow louder. We investigated whether the multisensorial processing of biological motion is subject to different constraints than ecologically invalid motion. Observers were presented with a visual point-light walker and/or synchronised auditory footsteps; the walker was either approaching the observer (looming motion) or walking away (receding motion). A scrambled point-light walker served as a control. Observers were asked to detect the walker's motion as quickly and as accurately as possible. In Experiment 1 we tested whether the reaction time advantage due to redundant information in the auditory and visual modality is specific for biological motion. We found no evidence for such an effect: the reaction time reduction was accounted for by statistical facilitation for both biological and scrambled motion. In Experiment 2, we dissociated the auditory and visual information and tested whether inconsistent motion directions across the auditory and visual modality yield longer reaction times in comparison to consistent motion directions. Here we find an effect specific to biological motion: motion incongruency leads to longer reaction times only when the visual walker is intact and recognisable as a human figure. If the figure of the walker is abolished by scrambling, motion incongruency has no effect on the speed of the observers' judgments. In conjunction with Experiment 1 this suggests that conflicting auditory-visual motion information of an intact human walker leads to interference and thereby delaying the response.

7 CFR 993.21a - Proper storage.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 8 2013-01-01 2013-01-01 false Proper storage. 993.21a Section 993.21a Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Order Regulating Handling Definitions § 993.21a Proper storage. Proper storage means storage of such...

7 CFR 993.21a - Proper storage.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 8 2011-01-01 2011-01-01 false Proper storage. 993.21a Section 993.21a Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order Regulating Handling Definitions § 993.21a Proper storage. Proper storage means storage of such...

7 CFR 993.21a - Proper storage.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 8 2012-01-01 2012-01-01 false Proper storage. 993.21a Section 993.21a Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order Regulating Handling Definitions § 993.21a Proper storage. Proper storage means storage of such...

7 CFR 993.21a - Proper storage.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 8 2014-01-01 2014-01-01 false Proper storage. 993.21a Section 993.21a Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Order Regulating Handling Definitions § 993.21a Proper storage. Proper storage means storage of such...

7 CFR 993.21a - Proper storage.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Proper storage. 993.21a Section 993.21a Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Order Regulating Handling Definitions § 993.21a Proper storage. Proper storage means storage of such...

Relativistic apsidal motion in eccentric eclipsing binaries

NASA Astrophysics Data System (ADS)

Wolf, M.; Claret, A.; Kotková, L.; Kučáková, H.; Kocián, R.; Brát, L.; Svoboda, P.; Šmelcer, L.

2010-01-01

Context. The study of apsidal motion in detached eclipsing binary systems is known to be an important source of information about stellar internal structure as well as the possibility of verifying of General Relativity outside the Solar System. Aims: As part of the long-term Ondřejov and Ostrava observational projects, we aim to measure precise times of minima for eccentric eclipsing binaries, needed for the accurate determination of apsidal motion, providing a suitable test of the effects of General Relativity. Methods: About seventy new times of minimum light recorded with photoelectric or CCD photometers were obtained for ten eccentric-orbit eclipsing binaries with significant relativistic apsidal motion. Their O-C diagrams were analysed using all reliable timings found in the literature, and new or improved elements of apsidal motion were obtained. Results: We confirm very long periods of apsidal motion for all systems. For BF Dra and V1094 Tau, we present the first apsidal-motion solution. The relativistic effects are dominant, representing up to 100% of the total observable apsidal-motion rate in several systems. The theoretical and observed values of the internal structure constant k 2 were compared for systems with lower relativistic contribution. Using the light-time effect solution, we predict a faint third component for V1094 Tau orbiting with a short period of about 8 years. Partly based on photoelectric observations secured at the Hvar Observatory, Faculty of Geodesy, Zagreb, Croatia, in October 2008.

Beam motions near separatrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. Ball et al.

1999-05-04

Experimental data on particle motion near the separatrix of the one dimensional (1-D) fourth-integer islands are an-alyzed. When the beam bunch is initially kicked to the separatrix orbit, we observed a strong decoherence in the coherent betatron motion. We find that, through intensive particle tracking simulation analysis, the decoherence has resulted from the beam being split into beamlets in the beta-tron phase space. However, we also observe an unexpected recoherence of coherence signal, which may result form a modulated closed orbit or the homoclinic structure near the separatrix.

Multiple-stage ambiguity in motion perception reveals global computation of local motion directions.

PubMed

Rider, Andrew T; Nishida, Shin'ya; Johnston, Alan

2016-12-01

The motion of a 1D image feature, such as a line, seen through a small aperture, or the small receptive field of a neural motion sensor, is underconstrained, and it is not possible to derive the true motion direction from a single local measurement. This is referred to as the aperture problem. How the visual system solves the aperture problem is a fundamental question in visual motion research. In the estimation of motion vectors through integration of ambiguous local motion measurements at different positions, conventional theories assume that the object motion is a rigid translation, with motion signals sharing a common motion vector within the spatial region over which the aperture problem is solved. However, this strategy fails for global rotation. Here we show that the human visual system can estimate global rotation directly through spatial pooling of locally ambiguous measurements, without an intervening step that computes local motion vectors. We designed a novel ambiguous global flow stimulus, which is globally as well as locally ambiguous. The global ambiguity implies that the stimulus is simultaneously consistent with both a global rigid translation and an infinite number of global rigid rotations. By the standard view, the motion should always be seen as a global translation, but it appears to shift from translation to rotation as observers shift fixation. This finding indicates that the visual system can estimate local vectors using a global rotation constraint, and suggests that local motion ambiguity may not be resolved until consistencies with multiple global motion patterns are assessed.

Space and motion in nature and Scripture: Galileo, Descartes, Newton.

PubMed

Janiak, Andrew

2015-06-01

In the Scholium to the Definitions in Principia mathematica, Newton departs from his main task of discussing space, time and motion by suddenly mentioning the proper method for interpreting Scripture. This is surprising, and it has long been ignored by scholars. In this paper, I argue that the Scripture passage in the Scholium is actually far from incidental: it reflects Newton's substantive concern, one evident in correspondence and manuscripts from the 1680s, that any general understanding of space, time and motion must enable readers to recognize the veracity of Biblical claims about natural phenomena, including the motion of the earth. This substantive concern sheds new light on an aspect of Newton's project in the Scholium. It also underscores Newton's originality in dealing with the famous problem of reconciling theological and philosophical conceptions of nature in the seventeenth century. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cluster observations of two separated cusp populations: double cusp or motion of the cusp?

NASA Astrophysics Data System (ADS)

Escoubet, C.-Philippe; Berchem, Jean; Trattner, Karlheinz; Pitout, Frederic; Richard, Robert; Taylor, Matt; Soucek, Jan; Grison, Benjamin; Laakso, Harri; Masson, Arnaud; Dunlop, Malcolm; Dandouras, Iannis; Reme, Henri; Fazakerley, Andrew; Daly, Patrick

2013-04-01

Modelling plasma entry in the polar cusp has been successful in reproducing ion dispersions observed in the cusp at low and mid-altitudes. The use of a realistic convection pattern allowed Wing et al. (2001) to predict double cusp signatures that were subsequently observed by the DMSP spacecraft. In this paper, we present a cusp crossing where two cusp populations are observed, separated by a gap around 1° ILAT wide. Cluster 1 (C1) and Cluster 2 (C2) observed these two cusp populations with a time delay of three minutes and about 15 and 42 minutes later, Cluster 4 (C4) and Cluster 3 (C3) observed, respectively, a single cusp population. A peculiarity of this event is the fact that the second cusp population seen on C1 and C2 was observed at the same time as the first cusp population on C4. This would tend to suggest that the two cusp populations were spatial features similar to the double cusp. Due to the nested crossing of C1 and C2 through the gap between the two cusp encounters, C2 being first to leave the cusp and last to re-enter it, these observations cannot be explained by two stable cusps with a gap of precipitation in between. On the other hand these observations are in agreement with a motion of the cusp first dawnward and then back duskward due to the effect of the IMF-By component.

An adaptive proper orthogonal decomposition method for model order reduction of multi-disc rotor system

NASA Astrophysics Data System (ADS)

Jin, Yulin; Lu, Kuan; Hou, Lei; Chen, Yushu

2017-12-01

The proper orthogonal decomposition (POD) method is a main and efficient tool for order reduction of high-dimensional complex systems in many research fields. However, the robustness problem of this method is always unsolved, although there are some modified POD methods which were proposed to solve this problem. In this paper, a new adaptive POD method called the interpolation Grassmann manifold (IGM) method is proposed to address the weakness of local property of the interpolation tangent-space of Grassmann manifold (ITGM) method in a wider parametric region. This method is demonstrated here by a nonlinear rotor system of 33-degrees of freedom (DOFs) with a pair of liquid-film bearings and a pedestal looseness fault. The motion region of the rotor system is divided into two parts: simple motion region and complex motion region. The adaptive POD method is compared with the ITGM method for the large and small spans of parameter in the two parametric regions to present the advantage of this method and disadvantage of the ITGM method. The comparisons of the responses are applied to verify the accuracy and robustness of the adaptive POD method, as well as the computational efficiency is also analyzed. As a result, the new adaptive POD method has a strong robustness and high computational efficiency and accuracy in a wide scope of parameter.

Direct observation of processive exoribonuclease motion using optical tweezers.

PubMed

Fazal, Furqan M; Koslover, Daniel J; Luisi, Ben F; Block, Steven M

2015-12-08

Bacterial RNases catalyze the turnover of RNA and are essential for gene expression and quality surveillance of transcripts. In Escherichia coli, the exoribonucleases RNase R and polynucleotide phosphorylase (PNPase) play critical roles in degrading RNA. Here, we developed an optical-trapping assay to monitor the translocation of individual enzymes along RNA-based substrates. Single-molecule records of motion reveal RNase R to be highly processive: one molecule can unwind over 500 bp of a structured substrate. However, enzyme progress is interrupted by pausing and stalling events that can slow degradation in a sequence-dependent fashion. We found that the distance traveled by PNPase through structured RNA is dependent on the A+U content of the substrate and that removal of its KH and S1 RNA-binding domains can reduce enzyme processivity without affecting the velocity. By a periodogram analysis of single-molecule records, we establish that PNPase takes discrete steps of six or seven nucleotides. These findings, in combination with previous structural and biochemical data, support an asymmetric inchworm mechanism for PNPase motion. The assay developed here for RNase R and PNPase is well suited to studies of other exonucleases and helicases.

Space Interferometry Mission: Dynamical Observations of Galaxies (SIMDOG)

NASA Technical Reports Server (NTRS)

Shaya, Edward J.; Borne, Kirk D.; Nusser, Adi; Peebles, P. J. E.; Tonry, John; Tully, Brent R.; Vogel, Stuart; Zaritsky, Dennis

2004-01-01

Space Interferometry Mission (SIM) will be used to obtain proper motions for a sample of 27 galaxies; the first proper motion measurements of galaxies beyond the satellite system of the Milky Way. SIM measurements lead to knowledge of the full 6-dimensional position and velocity vector of each galaxy. In conjunction with new gravitational flow models, the result will be the first total mass measurements of individual galaxies. The project, includes developnient of powerful theoretical methods for orbital calculations. This SIM study will lead to vastly improved determinations of individual galaxy masses, halo sizes, and the fractional contribution of dark matter. Astronomers have struggled to calculate the orbits of galaxies with only position and redshift information. Traditional N-body techniques are unsuitable for an analysis backward in time from a present distribution if any components of velocity or position are not very precisely known.

Orbit-attitude coupled motion around small bodies: Sun-synchronous orbits with Sun-tracking attitude motion

NASA Astrophysics Data System (ADS)

Kikuchi, Shota; Howell, Kathleen C.; Tsuda, Yuichi; Kawaguchi, Jun'ichiro

2017-11-01

The motion of a spacecraft in proximity to a small body is significantly perturbed due to its irregular gravity field and solar radiation pressure. In such a strongly perturbed environment, the coupling effect of the orbital and attitude motions exerts a large influence that cannot be neglected. However, natural orbit-attitude coupled dynamics around small bodies that are stationary in both orbital and attitude motions have yet to be observed. The present study therefore investigates natural coupled motion that involves both a Sun-synchronous orbit and Sun-tracking attitude motion. This orbit-attitude coupled motion enables a spacecraft to maintain its orbital geometry and attitude state with respect to the Sun without requiring active control. Therefore, the proposed method can reduce the use of an orbit and attitude control system. This paper first presents analytical conditions to achieve Sun-synchronous orbits and Sun-tracking attitude motion. These analytical solutions are then numerically propagated based on non-linear coupled orbit-attitude equations of motion. Consequently, the possibility of implementing Sun-synchronous orbits with Sun-tracking attitude motion is demonstrated.

Kinesthetic information disambiguates visual motion signals.

PubMed

Hu, Bo; Knill, David C

2010-05-25

Numerous studies have shown that extra-retinal signals can disambiguate motion information created by movements of the eye or head. We report a new form of cross-modal sensory integration in which the kinesthetic information generated by active hand movements essentially captures ambiguous visual motion information. Several previous studies have shown that active movement can bias observers' percepts of bi-stable stimuli; however, these effects seem to be best explained by attentional mechanisms. We show that kinesthetic information can change an otherwise stable perception of motion, providing evidence of genuine fusion between visual and kinesthetic information. The experiments take advantage of the aperture problem, in which the motion of a one-dimensional grating pattern behind an aperture, while geometrically ambiguous, appears to move stably in the grating normal direction. When actively moving the pattern, however, the observer sees the motion to be in the hand movement direction. Copyright 2010 Elsevier Ltd. All rights reserved.

Acoustic facilitation of object movement detection during self-motion

PubMed Central

Calabro, F. J.; Soto-Faraco, S.; Vaina, L. M.

2011-01-01

In humans, as well as most animal species, perception of object motion is critical to successful interaction with the surrounding environment. Yet, as the observer also moves, the retinal projections of the various motion components add to each other and extracting accurate object motion becomes computationally challenging. Recent psychophysical studies have demonstrated that observers use a flow-parsing mechanism to estimate and subtract self-motion from the optic flow field. We investigated whether concurrent acoustic cues for motion can facilitate visual flow parsing, thereby enhancing the detection of moving objects during simulated self-motion. Participants identified an object (the target) that moved either forward or backward within a visual scene containing nine identical textured objects simulating forward observer translation. We found that spatially co-localized, directionally congruent, moving auditory stimuli enhanced object motion detection. Interestingly, subjects who performed poorly on the visual-only task benefited more from the addition of moving auditory stimuli. When auditory stimuli were not co-localized to the visual target, improvements in detection rates were weak. Taken together, these results suggest that parsing object motion from self-motion-induced optic flow can operate on multisensory object representations. PMID:21307050

Difference of Horizontal-to-Vertical (H/V) Spectral Ratios of Microtremors and Earthquake Motions: Theory and Observation

NASA Astrophysics Data System (ADS)

Kawase, H.; Nagashima, F.; Matsushima, S.; Sanchez-Sesma, F. J.

2013-05-01

Horizontal-to-vertical spectral ratios (HVRs) of microtremors have been traditionally interpreted theoretically as representing the Rayleigh wave ellipticity or just utilized a convenient tool to extract predominant periods of ground. However, based on the diffuse field theory (Sánchez-Sesma et al., 2011) the microtremor H/V spectral ratios (MHVRs) correspond to the square root of the ratio of the imaginary part of horizontal displacement for a horizontally applied unit harmonic load and the imaginary part of vertical displacement for a vertically applied unit load. The same diffuse field concept leads us to derive a simple formula for earthquake HVRs (EHVRs), that is, the ratio of the horizontal motion on the surface for a vertical incidence of S wave divided by the vertical motion on the surface for a vertical incidence of P wave with a fixed coefficient (Kawase et al., 2011). The difference for EHVRs comes from the fact that primary contribution of earthquake motions would be of plane body waves. Traditionally EHVRs are interpreted as the responses of inclined SV wave incidence only for their S wave portions. Without these compact theoretical solutions, EHVRs and MHVRs are either considered to be very similar/equivalent, or totally different in the previous studies. With these theoretical solutions we need to re-focus our attention on the difference of HVRs. Thus we have compared here HVRs at several dozens of strong motion stations in Japan. When we compared observed HVRs we found that EHVRs tend to be higher in general than the MHVRs, especially around their peaks. As previously reported, their general shapes share the common features. Especially their fundamental peak and trough frequencies show quite a good match to each other. However, peaks in EHVRs in the higher frequency range would not show up in MHVRs. When we calculated theoretical HVRs separately at these target sites, their basic characteristics correspond to these observed differences. At this

General Automatic Components of Motion Sickness

NASA Technical Reports Server (NTRS)

Suter, S.; Toscano, W. B.; Kamiya, J.; Naifeh, K.

1985-01-01

A body of investigations performed in support of experiments aboard the space shuttle, and designed to counteract the symptoms of Space Adaptation Syndrome, which resemble those of motion sickness on Earth is reviewed. For these supporting studies, the automatic manifestations of earth-based motion sickness was examined. Heart rate, respiration rate, finger pulse volume and basal skin resistance were measured on 127 men and women before, during and after exposure to nauseogenic rotating chair tests. Significant changes in all autonomic responses were observed across the tests. Significant differences in autonomic responses among groups divided according to motion sickness susceptibility were also observed. Results suggest that the examination of autonomic responses as an objective indicator of motion sickness malaise is warranted and may contribute to the overall understanding of the syndrome on Earth and in Space.

Multiepoch VLBI observations of 4C 39.25 - Superluminal motion amid stationary structure

NASA Technical Reports Server (NTRS)

Shaffer, David B.; Marscher, Alan P.; Marcaide, Jon; Romney, Jonathan D.

1987-01-01

Eight VLBI maps of the quasar 4C 39.25 are presented, covering the time interval November 1979 to July 1985. During this period the compact components at the eastern and western ends of the source remained roughly stationary with respect to each other. A third component emerged from the western component in 1982 and proceeded to move (relative to the other two components) eastward at a rate of 0.16 + or - 0.02 marcsec per year. This corresponds to an average apparent speed between 3.2c and 8.4c for Hubble's constant between 100 and 50 km/s Mpc and q0 between 1 and 0. This superluminal motion contrasts with the stationary structure observed in the 1970s and also still observed between the eastern and western ends of the source. Possible explanations include superluminal feeding of a stationary compact counterpart to a classical radio lobe, an obstacle in a relativistic jet, a relativistic jet which alternatively expands and contracts owing to gradients in the confining pressure, and gravitational lensing of the compact radio emission.

Modal-Power-Based Haptic Motion Recognition

NASA Astrophysics Data System (ADS)

Kasahara, Yusuke; Shimono, Tomoyuki; Kuwahara, Hiroaki; Sato, Masataka; Ohnishi, Kouhei

Motion recognition based on sensory information is important for providing assistance to human using robots. Several studies have been carried out on motion recognition based on image information. However, in the motion of humans contact with an object can not be evaluated precisely by image-based recognition. This is because the considering force information is very important for describing contact motion. In this paper, a modal-power-based haptic motion recognition is proposed; modal power is considered to reveal information on both position and force. Modal power is considered to be one of the defining features of human motion. A motion recognition algorithm based on linear discriminant analysis is proposed to distinguish between similar motions. Haptic information is extracted using a bilateral master-slave system. Then, the observed motion is decomposed in terms of primitive functions in a modal space. The experimental results show the effectiveness of the proposed method.

Proper Names a Cognitive-Philosophical Study

ERIC Educational Resources Information Center

Garcia-Ramirez, Eduardo

2010-01-01

Proper Names appear at the heart of several debates in philosophy and the cognitive sciences. These include "reference", "intentionality", and the nature of "belief" as well as "language acquisition", "cognitive development", and "memory". This dissertation follows a cognitive approach to the philosophical problems posed by proper names. It puts…

SAGITTARIUS STREAM THREE-DIMENSIONAL KINEMATICS FROM SLOAN DIGITAL SKY SURVEY STRIPE 82

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koposov, Sergey E.; Belokurov, Vasily; Evans, N. Wyn

2013-04-01

Using multi-epoch observations of the Stripe 82 region from the Sloan Digital Sky Survey (SDSS), we measure precise statistical proper motions of the stars in the Sagittarius (Sgr) stellar stream. The multi-band photometry and SDSS radial velocities allow us to efficiently select Sgr members and thus enhance the proper-motion precision to {approx}0.1 mas yr{sup -1}. We measure separately the proper motion of a photometrically selected sample of the main-sequence turn-off stars, as well as spectroscopically selected Sgr giants. The data allow us to determine the proper motion separately for the two Sgr streams in the south found in Koposov etmore » al. Together with the precise velocities from SDSS, our proper motions provide exquisite constraints of the three-dimensional motions of the stars in the Sgr streams.« less

Ground-Motion Variability for a Strike-Slip Earthquake from Broadband Ground-Motion Simulations

NASA Astrophysics Data System (ADS)

Iwaki, A.; Maeda, T.; Morikawa, N.; Fujiwara, H.

2016-12-01

One of the important issues in seismic hazard analysis is the evaluation of ground-motion variability due to the epistemic and aleatory uncertainties in various aspects of ground-motion simulations. This study investigates the within-event ground-motion variability in broadband ground-motion simulations for strike-slip events. We conduct ground-motion simulations for a past event (2000 MW6.6 Tottori earthquake) using a set of characterized source models (e.g. Irikura and Miyake, 2011) considering aleatory variability. Broadband ground motion is computed by a hybrid approach that combines a 3D finite-difference method (> 1 s) and the stochastic Green's function method (< 1 s), using the 3D velocity model J-SHIS v2. We consider various locations of the asperities, which are defined as the regions with large slip and stress drop within the fault, and the rupture nucleation point (hypocenter). Ground motion records at 29 K-NET and KiK-net stations are used to validate our simulations. By comparing the simulated and observed ground motion, we found that the performance of the simulations is acceptable under the condition that the source parameters are poorly constrained. In addition to the observation stations, we set 318 virtual receivers with the spatial intervals of 10 km for statistical analysis of the simulated ground motion. The maximum fault-distance is 160 km. Standard deviation (SD) of the simulated acceleration response spectra (Sa, 5% damped) of RotD50 component (Boore, 2010) is investigated at each receiver. SD from 50 different patterns of asperity locations is generally smaller than 0.15 in terms of log10 (0.34 in natural log). It shows dependence on distance at periods shorter than 1 s; SD increases as the distance decreases. On the other hand, SD from 39 different hypocenter locations is again smaller than 0.15 in log10, and showed azimuthal dependence at long periods; it increases as the rupture directivity parameter Xcosθ(Somerville et al. 1997

Rotational motions from the 2016, Central Italy seismic sequence, as observed by an underground ring laser gyroscope

NASA Astrophysics Data System (ADS)

Simonelli, A.; Igel, H.; Wassermann, J.; Belfi, J.; Di Virgilio, A.; Beverini, N.; De Luca, G.; Saccorotti, G.

2018-05-01

We present the analysis of rotational and translational ground motions from earthquakes recorded during October/November, 2016, in association with the Central Italy seismic-sequence. We use co-located measurements of the vertical ground rotation rate from a large ring laser gyroscope (RLG), and the three components of ground velocity from a broadband seismometer. Both instruments are positioned in a deep underground environment, within the Gran Sasso National Laboratories (LNGS) of the Istituto Nazionale di Fisica Nucleare (INFN). We collected dozens of events spanning the 3.5-5.9 Magnitude range, and epicentral distances between 30 km and 70 km. This data set constitutes an unprecedented observation of the vertical rotational motions associated with an intense seismic sequence at local distance. Under the plane wave approximation we process the data set in order to get an experimental estimation of the events back azimuth. Peak values of rotation rate (PRR) and horizontal acceleration (PGA) are markedly correlated, according to a scaling constant which is consistent with previous measurements from different earthquake sequences. We used a prediction model in use for Italy to calculate the expected PGA at the recording site, obtaining consequently predictions for PRR. Within the modeling uncertainties, predicted rotations are consistent with the observed ones, suggesting the possibility of establishing specific attenuation models for ground rotations, like the scaling of peak velocity and peak acceleration in empirical ground-motion prediction relationships. In a second step, after identifying the direction of the incoming wave-field, we extract phase velocity data using the spectral ratio of the translational and rotational components.. This analysis is performed over time windows associated with the P-coda, S-coda and Lg phase. Results are consistent with independent estimates of shear-wave velocities in the shallow crust of the Central Apennines.

Self-evaluation on Motion Adaptation for Service Robots

NASA Astrophysics Data System (ADS)

Funabora, Yuki; Yano, Yoshikazu; Doki, Shinji; Okuma, Shigeru

We suggest self motion evaluation method to adapt to environmental changes for service robots. Several motions such as walking, dancing, demonstration and so on are described with time series patterns. These motions are optimized with the architecture of the robot and under certain surrounding environment. Under unknown operating environment, robots cannot accomplish their tasks. We propose autonomous motion generation techniques based on heuristic search with histories of internal sensor values. New motion patterns are explored under unknown operating environment based on self-evaluation. Robot has some prepared motions which realize the tasks under the designed environment. Internal sensor values observed under the designed environment with prepared motions show the interaction results with the environment. Self-evaluation is composed of difference of internal sensor values between designed environment and unknown operating environment. Proposed method modifies the motions to synchronize the interaction results on both environment. New motion patterns are generated to maximize self-evaluation function without external information, such as run length, global position of robot, human observation and so on. Experimental results show that the possibility to adapt autonomously patterned motions to environmental changes.

A Pursuit Theory Account for the Perception of Common Motion in Motion Parallax.

PubMed

Ratzlaff, Michael; Nawrot, Mark

2016-09-01

The visual system uses an extraretinal pursuit eye movement signal to disambiguate the perception of depth from motion parallax. Visual motion in the same direction as the pursuit is perceived nearer in depth while visual motion in the opposite direction as pursuit is perceived farther in depth. This explanation of depth sign applies to either an allocentric frame of reference centered on the fixation point or an egocentric frame of reference centered on the observer. A related problem is that of depth order when two stimuli have a common direction of motion. The first psychophysical study determined whether perception of egocentric depth order is adequately explained by a model employing an allocentric framework, especially when the motion parallax stimuli have common rather than divergent motion. A second study determined whether a reversal in perceived depth order, produced by a reduction in pursuit velocity, is also explained by this model employing this allocentric framework. The results show than an allocentric model can explain both the egocentric perception of depth order with common motion and the perceptual depth order reversal created by a reduction in pursuit velocity. We conclude that an egocentric model is not the only explanation for perceived depth order in these common motion conditions. © The Author(s) 2016.

Dynamic strain and rotation ground motions of the 2011 Tohoku earthquake from dense high-rate GPS observations in Taiwan

NASA Astrophysics Data System (ADS)

Huang, B. S.; Rau, R. J.; Lin, C. J.; Kuo, L. C.

2017-12-01

Seismic waves generated by the 2011 Mw 9.0 Tohoku, Japan earthquake were well recorded by continuous GPS in Taiwan. Those GPS were operated in one hertz sampling rate and densely distributed in Taiwan Island. Those continuous GPS observations and the precise point positioning technique provide an opportunity to estimate spatial derivatives from absolute ground motions of this giant teleseismic event. In this study, we process and investigate more than one and half hundred high-rate GPS displacements and its spatial derivatives, thus strain and rotations, to compare to broadband seismic and rotational sensor observations. It is shown that continuous GPS observations are highly consistent with broadband seismic observations during its surface waves across Taiwan Island. Several standard Geodesy and seismic array analysis techniques for spatial gradients have been applied to those continuous GPS time series to determine its dynamic strain and rotation time histories. Results show that those derivate GPS vertical axis ground rotations are consistent to seismic array determined rotations. However, vertical rotation-rate observations from the R1 rotational sensors have low resolutions and could not compared with GPS observations for this special event. For its dese spatial distribution of GPS stations in Taiwan Island, not only wavefield gradient time histories at individual site was obtained but also 2-D spatial ground motion fields were determined in this study also. In this study, we will report the analyzed results of those spatial gradient wavefields of the 2011 Tohoku earthquake across Taiwan Island and discuss its geological implications.

Disorders of motion and depth.

PubMed

Nawrot, Mark

2003-08-01

Damage to the human homologue of area MT produces a motion perception deficit similar to that found in the monkey with MT lesions. Even temporary disruption of MT processing with transcranial magnetic stimulation can produce a temporary akinetopsia [127]. Motion perception deficits, however, also are found with a variety of subcortical lesions and other neurologic disorders that can best be described as causing a disconnection within the motion processing stream. The precise role of these subcortical structures, such as the cerebellum, remains to be determined. Simple motion perception, moreover, is only a part of MT function. It undoubtedly has an important role in the perception of depth from motion and stereopsis [112]. Psychophysical studies using aftereffects in normal observers suggest a link between stereo mechanisms and the perception of depth from motion [9-11]. There is even a simple correlation between stereo acuity and the perception of depth from motion [128]. Future studies of patients with cortical lesions will take a closer look at depth perception in association with motion perception and should provide a better understanding of how motion and depth are processed together.

Central Inhibition Ability Modulates Attention-Induced Motion Blindness

ERIC Educational Resources Information Center

Milders, Maarten; Hay, Julia; Sahraie, Arash; Niedeggen, Michael

2004-01-01

Impaired motion perception can be induced in normal observers in a rapid serial visual presentation task. Essential for this effect is the presence of motion distractors prior to the motion target, and we proposed that this attention-induced motion blindness results from high-level inhibition produced by the distractors. To investigate this, we…

On-Line Detection and Segmentation of Sports Motions Using a Wearable Sensor.

PubMed

Kim, Woosuk; Kim, Myunggyu

2018-03-19

In sports motion analysis, observation is a prerequisite for understanding the quality of motions. This paper introduces a novel approach to detect and segment sports motions using a wearable sensor for supporting systematic observation. The main goal is, for convenient analysis, to automatically provide motion data, which are temporally classified according to the phase definition. For explicit segmentation, a motion model is defined as a sequence of sub-motions with boundary states. A sequence classifier based on deep neural networks is designed to detect sports motions from continuous sensor inputs. The evaluation on two types of motions (soccer kicking and two-handed ball throwing) verifies that the proposed method is successful for the accurate detection and segmentation of sports motions. By developing a sports motion analysis system using the motion model and the sequence classifier, we show that the proposed method is useful for observation of sports motions by automatically providing relevant motion data for analysis.

Synthesis of High-Frequency Ground Motion Using Information Extracted from Low-Frequency Ground Motion

NASA Astrophysics Data System (ADS)

Iwaki, A.; Fujiwara, H.

2012-12-01

Broadband ground motion computations of scenario earthquakes are often based on hybrid methods that are the combinations of deterministic approach in lower frequency band and stochastic approach in higher frequency band. Typical computation methods for low-frequency and high-frequency (LF and HF, respectively) ground motions are the numerical simulations, such as finite-difference and finite-element methods based on three-dimensional velocity structure model, and the stochastic Green's function method, respectively. In such hybrid methods, LF and HF wave fields are generated through two different methods that are completely independent of each other, and are combined at the matching frequency. However, LF and HF wave fields are essentially not independent as long as they are from the same event. In this study, we focus on the relation among acceleration envelopes at different frequency bands, and attempt to synthesize HF ground motion using the information extracted from LF ground motion, aiming to propose a new method for broad-band strong motion prediction. Our study area is Kanto area, Japan. We use the K-NET and KiK-net surface acceleration data and compute RMS envelope at four frequency bands: 0.5-1.0 Hz, 1.0-2.0 Hz, 2.0-4.0 Hz, .0-8.0 Hz, and 8.0-16.0 Hz. Taking the ratio of the envelopes of adjacent bands, we find that the envelope ratios have stable shapes at each site. The empirical envelope-ratio characteristics are combined with low-frequency envelope of the target earthquake to synthesize HF ground motion. We have applied the method to M5-class earthquakes and a M7 target earthquake that occurred in the vicinity of Kanto area, and successfully reproduced the observed HF ground motion of the target earthquake. The method can be applied to a broad band ground motion simulation for a scenario earthquake by combining numerically-computed low-frequency (~1 Hz) ground motion with the empirical envelope ratio characteristics to generate broadband ground motion

Detection of individual atoms in helium buffer gas and observation of their real-time motion

NASA Technical Reports Server (NTRS)

Pan, C. L.; Prodan, J. V.; Fairbank, W. M., Jr.; She, C. Y.

1980-01-01

Single atoms are detected and their motion measured for the first time to our knowledge by the fluorescence photon-burst method in the presence of large quantities of buffer gas. A single-clipped digital correlator records the photon burst in real time and displays the atom's transit time across the laser beam. A comparison is made of the special requirements for single-atom detection in vacuum and in a buffer gas. Finally, the probability distribution of the bursts from many atoms is measured. It further proves that the bursts observed on resonance are due to single atoms and not simply to noise fluctuations.

Analysis of Local Variations in Free Field Seismic Ground Motion.

DTIC Science & Technology

1981-01-01

analysis) can conveniently account for material damping through the introduction of complex moduli into the equations of motion. This method can...determined, and the total response is obtained by superposition. This technique, however, can not properly account for the spatial variation of damping...2.9. Most available data only consider the variation of shear modulus and damping ratio with shear strain amplitude. In principle , two moduli and two

Maggi's equations of motion and the determination of constraint reactions

NASA Astrophysics Data System (ADS)

Papastavridis, John G.

1990-04-01

This paper presents a geometrical derivation of the constraint reaction-free equations of Maggi for mechanical systems subject to linear (first-order) nonholonomic and/or holonomic constraints. These results follow directly from the proper application of the concepts of virtual displacement and quasi-coordinates to the variational equation of motion, i.e., Lagrange's principle. The method also makes clear how to compute the constraint reactions (kinetostatics) without introducing Lagrangian multipliers.

Motion-based prediction explains the role of tracking in motion extrapolation.

PubMed

Khoei, Mina A; Masson, Guillaume S; Perrinet, Laurent U

2013-11-01

During normal viewing, the continuous stream of visual input is regularly interrupted, for instance by blinks of the eye. Despite these frequents blanks (that is the transient absence of a raw sensory source), the visual system is most often able to maintain a continuous representation of motion. For instance, it maintains the movement of the eye such as to stabilize the image of an object. This ability suggests the existence of a generic neural mechanism of motion extrapolation to deal with fragmented inputs. In this paper, we have modeled how the visual system may extrapolate the trajectory of an object during a blank using motion-based prediction. This implies that using a prior on the coherency of motion, the system may integrate previous motion information even in the absence of a stimulus. In order to compare with experimental results, we simulated tracking velocity responses. We found that the response of the motion integration process to a blanked trajectory pauses at the onset of the blank, but that it quickly recovers the information on the trajectory after reappearance. This is compatible with behavioral and neural observations on motion extrapolation. To understand these mechanisms, we have recorded the response of the model to a noisy stimulus. Crucially, we found that motion-based prediction acted at the global level as a gain control mechanism and that we could switch from a smooth regime to a binary tracking behavior where the dot is tracked or lost. Our results imply that a local prior implementing motion-based prediction is sufficient to explain a large range of neural and behavioral results at a more global level. We show that the tracking behavior deteriorates for sensory noise levels higher than a certain value, where motion coherency and predictability fail to hold longer. In particular, we found that motion-based prediction leads to the emergence of a tracking behavior only when enough information from the trajectory has been accumulated

Induced rotational motion with nonabutting inducing and induced stimuli: implications regarding two forms of induced motion.

PubMed

Reinhardt-Rutland, A H

2003-07-01

Induced motion is the illusory motion of a static stimulus in the opposite direction to a moving stimulus. Two types of induced motion have been distinguished: (a) when the moving stimulus is distant from the static stimulus and undergoes overall displacement, and (b) when the moving stimulus is pattern viewed within fixed boundaries that abut the static stimulus. Explanations of the 1st type of induced motion refer to mediating phenomena, such as vection, whereas the 2nd type is attributed to local processing by motion-sensitive neurons. The present research was directed to a display that elicited induced rotational motion with the characteristics of both types of induced motion: the moving stimulus lay within fixed boundaries, but the inducing and induced stimuli were distant from each other. The author investigated the properties that distinguished the two types of induced motion. In 3 experiments, induced motion persisted indefinitely, interocular transfer of the aftereffect of induced motion was limited to about 20%, and the time-course of the aftereffect of induced motion could not be attributed to vection. Those results were consistent with fixed-boundary induced motion. However, they could not be explained by local processing. Instead, the results might reflect the detection of object motion within a complex flow-field that resulted from the observer's motion.

Depletion force induced collective motion of microtubules driven by kinesin

NASA Astrophysics Data System (ADS)

Inoue, Daisuke; Mahmot, Bulbul; Kabir, Arif Md. Rashedul; Farhana, Tamanna Ishrat; Tokuraku, Kiyotaka; Sada, Kazuki; Konagaya, Akihiko; Kakugo, Akira

2015-10-01

Collective motion is a fascinating example of coordinated behavior of self-propelled objects, which is often associated with the formation of large scale patterns. Nowadays, the in vitro gliding assay is being considered a model system to experimentally investigate various aspects of group behavior and pattern formation by self-propelled objects. In the in vitro gliding assay, cytoskeletal filaments F-actin or microtubules are driven by the surface immobilized associated biomolecular motors myosin or dynein respectively. Although the F-actin/myosin or microtubule/dynein system was found to be promising in understanding the collective motion and pattern formation by self-propelled objects, the most widely used biomolecular motor system microtubule/kinesin could not be successfully employed so far in this regard. Failure in exhibiting collective motion by kinesin driven microtubules is attributed to the intrinsic properties of kinesin, which was speculated to affect the behavior of individual gliding microtubules and mutual interactions among them. In this work, for the first time, we have demonstrated the collective motion of kinesin driven microtubules by regulating the mutual interaction among the gliding microtubules, by employing a depletion force among them. Proper regulation of the mutual interaction among the gliding microtubules through the employment of the depletion force was found to allow the exhibition of collective motion and stream pattern formation by the microtubules. This work offers a universal means for demonstrating the collective motion using the in vitro gliding assay of biomolecular motor systems and will help obtain a meticulous understanding of the fascinating coordinated behavior and pattern formation by self-propelled objects.Collective motion is a fascinating example of coordinated behavior of self-propelled objects, which is often associated with the formation of large scale patterns. Nowadays, the in vitro gliding assay is being

Visual motion integration for perception and pursuit

NASA Technical Reports Server (NTRS)

Stone, L. S.; Beutter, B. R.; Lorenceau, J.

2000-01-01

To examine the relationship between visual motion processing for perception and pursuit, we measured the pursuit eye-movement and perceptual responses to the same complex-motion stimuli. We show that humans can both perceive and pursue the motion of line-figure objects, even when partial occlusion makes the resulting image motion vastly different from the underlying object motion. Our results show that both perception and pursuit can perform largely accurate motion integration, i.e. the selective combination of local motion signals across the visual field to derive global object motion. Furthermore, because we manipulated perceived motion while keeping image motion identical, the observed parallel changes in perception and pursuit show that the motion signals driving steady-state pursuit and perception are linked. These findings disprove current pursuit models whose control strategy is to minimize retinal image motion, and suggest a new framework for the interplay between visual cortex and cerebellum in visuomotor control.

Coastal Vertical Land motion in the German Bight

NASA Astrophysics Data System (ADS)

Becker, Matthias; Fenoglio, Luciana; Reckeweg, Florian

2017-04-01

In the framework of the ESA Sea Level Climate Change Initiative (CCI) we analyse a set of GNSS equipped tide gauges at the German Bight. Main goals are the determination of tropospheric zenith delay corrections for altimetric observations, precise coordinates in ITRF2008 and vertical land motion (VLM) rates of the tide gauge stations. These are to be used for georeferencing the tide gauges and the correction of tide gauge observations for VLM. The set of stations includes 38 GNSS stations. 19 stations are in the German Bight, where 15 of them belong to the Bundesanstalt für Gewässerkunde, 3 to EUREF and 1 to GREF. These stations are collocated with tide gauges (TGs). The other 19 GNSS stations in the network belong to EUREF, IGS and GREF. We analyse data in the time span from 2008 till the end of 2016 with the Bernese PPP processing approach. Data are partly rather noisy and disturbed by offsets and data gaps at the coastal TG sites. Special effort is therefore put into a proper estimation of the VLM. We use FODITS (Ostini2012), HECTOR (Bos et al, 2013), CATS (Williams, 2003) and the MIDAS approach of Blewitt (2016) to robustly derive rates and realistic error estimates. The results are compared to those published by the European Permanent Network (EPN), ITRF and the Système d'Observation du Niveau des Eaux Littorales (SONEL) for common stations. Vertical motion is small in general, at the -1 to -2 mm/yr level for most coastal stations. A comparison of the standard deviations of the velocity differences to EPN with the mean values of the estimated velocity standard deviations for our solution shows a very good agreement of the estimated velocities and their standard deviations with the reference solution from EPN. In the comparison with results by SONEL the standard deviation of the differences is slightly higher. The discrepancies may arise from differences in the time span analyzed and gaps, offsets and data preprocessing. The combined estimation of functional

Stellar motion induced by gravitational instabilities in protoplanetary discs

NASA Astrophysics Data System (ADS)

Michael, Scott; Durisen, R. H.

2010-07-01

We test the effect of assumptions about stellar motion on the behaviour of gravitational instabilities (GIs) in protoplanetary discs around solar-type stars by performing two simulations that are identical in all respects except the treatment of the star. In one simulation, the star is assumed to remain fixed at the centre of the inertial reference frame. In the other, stellar motion is handled properly by including an indirect potential in the hydrodynamic equations to model the star's reference frame as one which is accelerated by star/disc interactions. The discs in both simulations orbit a solar mass star, initially extend from 2.3 to 40 au with a ϖ-1/2 surface density profile, and have a total mass of 0.14 Msolar. The γ = 5/3 ideal gas is assumed to cool everywhere with a constant cooling time of two outer rotation periods. The overall behaviour of the disc evolution is similar, except for weakening in various measures of GI activity by about at most tens of per cent for the indirect potential case. Overall conclusions about disc evolution in earlier papers by our group, where the star was always assumed to be fixed in an inertial frame, remain valid. There is no evidence for independent one-armed instabilities, like the Stimulation by the Long-range Interaction of Newtonian Gravity (SLING), in either simulation. On the other hand, the stellar motion about the system centre of mass (COM) in the simulation with the indirect potential is substantial, up to 0.25 au during the burst phase, as GIs initiate, and averaging about 0.9 au during the asymptotic phase, when the GIs reach an overall balance of heating and cooling. These motions appear to be a stellar response to non-linear interactions between discrete global spiral modes in both the burst and asymptotic phases of the evolution, and the star's orbital motion about the COM reflects the orbit periods of disc material near the corotation radii of the dominant spiral waves. This motion is, in principle

Grs 1915+105: a superluminal source in the Galaxy.

PubMed Central

Rodríguez, L F; Mirabel, I F

1995-01-01

We present the results of additional observations of the high energy source GRS 1915+105, which produces ejecta with apparent superluminal motions. The observations reported here were carried out with the Very Large Array at 3.5 cm and 20 cm. The 3.5-cm observations made during 1994 May allowed us to continue following the proper motions of the bright 1994 March 19 ejecta, as well as those of a subsequent, fainter ejection. The proper motions of the 1994 March 19 ejecta continued to be ballistic (i.e., constant) over the period of about 75 days where they remained detectable. From the observations in 1994 March-May we have identified three ejections of pairs of plasma clouds moving ballistically in approximately the same direction on the sky with similar proper motions. The 20-cm observations made during 1994 November and December were used to search, yet unsuccessfully, for extended jets or lobes associated with GRS 1915+105. PMID:11607605

Rigidity and definition of Caribbean plate motion from COCONet and campaign GPS observations

NASA Astrophysics Data System (ADS)

Mattioli, Glen; Miller, Jamie; DeMets, Charles; Jansma, Pamela

2014-05-01

The currently accepted kinematic model of the Caribbean plate presented by DeMets et al. (2007) is based on velocities from 6 continuous and 14 campaign GPS sites. COCONet is a multi-hazard GPS-Met observatory, which extends the existing infrastructure of the Plate Boundary Observatory in North America into the Caribbean basin. In 2010, UNAVCO in collaboration with UCAR, was funded by NSF to design, build, and initially maintain a network of 50 new cGPS/Met sites and include data from another 50 existing sites in the Caribbean region. The current COCONet siting plan calls for 46 new stations, 21 refurbished stations, and 77 existing stations across 26 nations in the Caribbean region. Data from all COCONet sites flow into the UNAVCO archive and are processed by the PBO analysis centers and are also processed independently by the UTA Geodesy Lab using GIPSY-OASISII (v.6.2) using an absolute point positioning strategy and final, precise orbits, clocks, and Earth orientation parameters from JPL in the IGS08 frame. We present here our refined estimate of Caribbean plate motion by evaluating data from an expanded number of stations with an improved spatial distribution. In order to better constrain the eastern margin of the plate near the Lesser Antilles subduction interface, campaign GPS observations have been collected on the island of Dominica over the last decade. These are combined with additional campaign observations from the western Caribbean, specifically from Honduras and Nicaragua. We have analyzed a total of 117 sites from the Caribbean region, including campaign data and the data from the cGPS stations that comprise COCONet. An updated velocity field for the Caribbean plate is presented and an inversion of the velocities for 24 sites yields a plate angular velocity that differs from previously published models. Our best fitting inversion to GPS velocities from these 24 sites suggests that 2-plate model for the Caribbean is required to fit the GPS

Rigidity and definition of Caribbean plate motion from COCONet and campaign GPS observations

NASA Astrophysics Data System (ADS)

Mattioli, G. S.; Miller, J. A.; DeMets, C.; Jansma, P. E.

2015-12-01

The kinematic model of the Caribbean plate presented by DeMets et al. (2007) is based on velocities from 6 continuous and 14 campaign GPS sites. COCONet is a multi-hazard GPS-Met observatory, which extends the existing infrastructure of the PBO in North America into the Caribbean basin. In 2010, UNAVCO in collaboration with UCAR, was funded by NSF to design, build, and initially maintain a network of 50 new cGPS/Met sites and include data from another 50 existing sites in the Caribbean region. The COCONet siting plan is for 46 new stations, 21 refurbished stations, and 77 existing stations across 26 nations in the Caribbean region. Data from all COCONet sites flow into the UNAVCO archive and are processed by the PBO analysis centers and are also processed independently by the UTA Geodesy Lab using GIPSY-OASISII (v.6.3) using an APP strategy and final, precise orbits, clocks, and EOP from JPL in the IGS08r frame. We present a refined estimate of Caribbean plate motion by evaluating data from an expanded number of stations with an improved spatial distribution. In order to better constrain the eastern margin of the plate near the Lesser Antilles subduction interface, campaign GPS observations have been collected on the island of Dominica over the last decade. These are combined with additional campaign observations from the western Caribbean, specifically from Honduras and Nicaragua. We have analyzed a total of 117 sites from the Caribbean region, including campaign data and the data from the cGPS stations that comprise COCONet. An updated velocity field for the Caribbean plate is presented and an inversion of the velocities for 24 sites yields a plate angular velocity that differs from previously published models. Our best fitting inversion to GPS velocities from these 24 sites suggests that 2-plate model for the Caribbean is required to fit the GPS observations, which implies that the Caribbean is undergoing modest (1-3 mm/yr) deformation within its interior. Some

Multisensory Self-Motion Compensation During Object Trajectory Judgments

PubMed Central

Dokka, Kalpana; MacNeilage, Paul R.; DeAngelis, Gregory C.; Angelaki, Dora E.

2015-01-01

Judging object trajectory during self-motion is a fundamental ability for mobile organisms interacting with their environment. This fundamental ability requires the nervous system to compensate for the visual consequences of self-motion in order to make accurate judgments, but the mechanisms of this compensation are poorly understood. We comprehensively examined both the accuracy and precision of observers' ability to judge object trajectory in the world when self-motion was defined by vestibular, visual, or combined visual–vestibular cues. Without decision feedback, subjects demonstrated no compensation for self-motion that was defined solely by vestibular cues, partial compensation (47%) for visually defined self-motion, and significantly greater compensation (58%) during combined visual–vestibular self-motion. With decision feedback, subjects learned to accurately judge object trajectory in the world, and this generalized to novel self-motion speeds. Across conditions, greater compensation for self-motion was associated with decreased precision of object trajectory judgments, indicating that self-motion compensation comes at the cost of reduced discriminability. Our findings suggest that the brain can flexibly represent object trajectory relative to either the observer or the world, but a world-centered representation comes at the cost of decreased precision due to the inclusion of noisy self-motion signals. PMID:24062317

Aging and the Visual Perception of Motion Direction: Solving the Aperture Problem.

PubMed

Shain, Lindsey M; Norman, J Farley

2018-07-01

An experiment required younger and older adults to estimate coherent visual motion direction from multiple motion signals, where each motion signal was locally ambiguous with respect to the true direction of pattern motion. Thus, accurate performance required the successful integration of motion signals across space (i.e., accurate performance required solution of the aperture problem) . The observers viewed arrays of either 64 or 9 moving line segments; because these lines moved behind apertures, their individual local motions were ambiguous with respect to direction (i.e., were subject to the aperture problem). Following 2.4 seconds of pattern motion on each trial (true motion directions ranged over the entire range of 360° in the fronto-parallel plane), the observers estimated the coherent direction of motion. There was an effect of direction, such that cardinal directions of pattern motion were judged with less error than oblique directions. In addition, a large effect of aging occurred-The average absolute errors of the older observers were 46% and 30.4% higher in magnitude than those exhibited by the younger observers for the 64 and 9 aperture conditions, respectively. Finally, the observers' precision markedly deteriorated as the number of apertures was reduced from 64 to 9.

General autonomic components of motion sickness

NASA Technical Reports Server (NTRS)

Cowings, Patricia S.; Suter, Steve; Toscano, William B.; Kamiya, Joe; Naifeh, Karen

1986-01-01

This report refers to a body of investigations directed toward the examination of autonomic nervous system responses to motion sickness. Heart rate, respiration rate, finger pulse volume, and basal skin resistance were measured on 127 men and women before, during, and after exposure to a nauseogenic rotating chair test. Significant changes in all autonomic responses were observed across the tests (p less than .05). Significant differences in autonomic responses among groups divided according to motion sickness susceptibility were also observed (p less than .05). Results suggest that the examination of autonomic responses as an objective indicator of motion sickness malaise is warranted and may contribute to the overall understanding of the syndrome.

Reference frames, gauge transformations and gravitomagnetism in the post-Newtonian theory of the lunar motion

NASA Astrophysics Data System (ADS)

Xie, Yi; Kopeikin, Sergei

2010-01-01

We construct a set of reference frames for description of the orbital and rotational motion of the Moon. We use a scalar-tensor theory of gravity depending on two parameters of the parametrized post-Newtonian (PPN) formalism and utilize the concepts of the relativistic resolutions on reference frames adopted by the International Astronomical Union in 2000. We assume that the solar system is isolated and space-time is asymptotically flat. The primary reference frame has the origin at the solar-system barycenter (SSB) and spatial axes are going to infinity. The SSB frame is not rotating with respect to distant quasars. The secondary reference frame has the origin at the Earth-Moon barycenter (EMB). The EMB frame is local with its spatial axes spreading out to the orbits of Venus and Mars and not rotating dynamically in the sense that both the Coriolis and centripetal forces acting on a free-falling test particle, moving with respect to the EMB frame, are excluded. Two other local frames, the geocentric (GRF) and the selenocentric (SRF) frames, have the origin at the center of mass of the Earth and Moon respectively. They are both introduced in order to connect the coordinate description of the lunar motion, observer on the Earth, and a retro-reflector on the Moon to the observable quantities which are the proper time and the laser-ranging distance. We solve the gravity field equations and find the metric tensor and the scalar field in all frames. We also derive the post-Newtonian coordinate transformations between the frames and analyze the residual gauge freedom of the solutions of the field equations. We discuss the gravitomagnetic effects in the barycentric equations of the motion of the Moon and argue that they are beyond the current accuracy of lunar laser ranging (LLR) observations.

The effect of regularization in motion compensated PET image reconstruction: a realistic numerical 4D simulation study.

PubMed

Tsoumpas, C; Polycarpou, I; Thielemans, K; Buerger, C; King, A P; Schaeffter, T; Marsden, P K

2013-03-21

Following continuous improvement in PET spatial resolution, respiratory motion correction has become an important task. Two of the most common approaches that utilize all detected PET events to motion-correct PET data are the reconstruct-transform-average method (RTA) and motion-compensated image reconstruction (MCIR). In RTA, separate images are reconstructed for each respiratory frame, subsequently transformed to one reference frame and finally averaged to produce a motion-corrected image. In MCIR, the projection data from all frames are reconstructed by including motion information in the system matrix so that a motion-corrected image is reconstructed directly. Previous theoretical analyses have explained why MCIR is expected to outperform RTA. It has been suggested that MCIR creates less noise than RTA because the images for each separate respiratory frame will be severely affected by noise. However, recent investigations have shown that in the unregularized case RTA images can have fewer noise artefacts, while MCIR images are more quantitatively accurate but have the common salt-and-pepper noise. In this paper, we perform a realistic numerical 4D simulation study to compare the advantages gained by including regularization within reconstruction for RTA and MCIR, in particular using the median-root-prior incorporated in the ordered subsets maximum a posteriori one-step-late algorithm. In this investigation we have demonstrated that MCIR with proper regularization parameters reconstructs lesions with less bias and root mean square error and similar CNR and standard deviation to regularized RTA. This finding is reproducible for a variety of noise levels (25, 50, 100 million counts), lesion sizes (8 mm, 14 mm diameter) and iterations. Nevertheless, regularized RTA can also be a practical solution for motion compensation as a proper level of regularization reduces both bias and mean square error.

MFP scanner motion characterization using self-printed target

NASA Astrophysics Data System (ADS)

Kim, Minwoong; Bauer, Peter; Wagner, Jerry K.; Allebach, Jan P.

2015-01-01

Multifunctional printers (MFP) are products that combine the functions of a printer, scanner, and copier. Our goal is to help customers to be able to easily diagnose scanner or print quality issues with their products by developing an automated diagnostic system embedded in the product. We specifically focus on the characterization of scanner motions, which may be defective due to irregular movements of the scan-head. The novel design of our test page and two-stage diagnostic algorithm are described in this paper. The most challenging issue is to evaluate the scanner performance properly when both printer and scanner units contribute to the motion errors. In the first stage called the uncorrected-print-error-stage, aperiodic and periodic motion behaviors are characterized in both the spatial and frequency domains. Since it is not clear how much of the error is contributed by each unit, the scanned input is statistically analyzed in the second stage called the corrected-print-error-stage. Finally, the described diagnostic algorithms output the estimated scan error and print error separately as RMS values of the displacement of the scan and print lines, respectively, from their nominal positions in the scanner or printer motion direction. We validate our test page design and approaches by ground truth obtained from a high-precision, chrome-on-glass reticle manufactured using semiconductor chip fabrication technologies.

Simultaneous teleseismic and geodetic observations of the stick-slip motion of an Antarctic ice stream.

PubMed

Wiens, Douglas A; Anandakrishnan, Sridhar; Winberry, J Paul; King, Matt A

2008-06-05

Long-period seismic sources associated with glacier motion have been recently discovered, and an increase in ice flow over the past decade has been suggested on the basis of secular changes in such measurements. Their significance, however, remains uncertain, as a relationship to ice flow has not been confirmed by direct observation. Here we combine long-period surface-wave observations with simultaneous Global Positioning System measurements of ice displacement to study the tidally modulated stick-slip motion of the Whillans Ice Stream in West Antarctica. The seismic origin time corresponds to slip nucleation at a region of the bed of the Whillans Ice Stream that is likely stronger than in surrounding regions and, thus, acts like an 'asperity' in traditional fault models. In addition to the initial pulse, two seismic arrivals occurring 10-23 minutes later represent stopping phases as the slip terminates at the ice stream edge and the grounding line. Seismic amplitude and average rupture velocity are correlated with tidal amplitude for the different slip events during the spring-to-neap tidal cycle. Although the total seismic moment calculated from ice rigidity, slip displacement, and rupture area is equivalent to an earthquake of moment magnitude seven (M(w) 7), seismic amplitudes are modest (M(s) 3.6-4.2), owing to the source duration of 20-30 minutes. Seismic radiation from ice movement is proportional to the derivative of the moment rate function at periods of 25-100 seconds and very long-period radiation is not detected, owing to the source geometry. Long-period seismic waves are thus useful for detecting and studying sudden ice movements but are insensitive to the total amount of slip.

Utilization of kinematical redundancy of a rehabilitation robot to produce compliant motions under limitation on actuator performance.

PubMed

Goto, Takaaki; Dobashi, Hiroki; Yoshikawa, Tsuneo; Loureiro, Rui C V; Harwin, William S; Miyamura, Yuga; Nagai, Kiyoshi

2017-07-01

This paper addresses the mechanical structure and control method of a redundant drive robot (RDR) to produce compliant motions, and show how the design parameters of the RDR can effect the produced motions and the mechanical and performance limitations of the actuators of the RDR. The structure and control method of the RDR can have been proper to produce compliant motions, but the effect of the design parameters of the RDR to the mechanical and performance limitations have not been clear. Therefore, the feasibility of producing compliant motions in the case of the prototype of the RDR is confirmed by conducting simulations and experiments, and then the design parameters of the RDR to the mechanical and performance limitations are verified by conducting simulations.

Experimental Study of Short-Time Brownian Motion

NASA Astrophysics Data System (ADS)

Mo, Jianyong; Simha, Akarsh; Riegler, David; Raizen, Mark

2015-03-01

We report our progress on the study of short-time Brownian motion of optically-trapped microspheres. In earlier work, we observed the instantaneous velocity of microspheres in gas and in liquid, verifying a prediction by Albert Einstein from 1907. We now report a more accurate test of the energy equipartition theorem for a particle in liquid. We also observe boundary effects on Brownian motion in liquid by setting a wall near the trapped particle, which changes the dynamics of the motion. We find that the velocity autocorrelation of the particle decreases faster as the particle gets closer to the wall.

Motion-based nearest vector metric for reference frame selection in the perception of motion.

PubMed

Agaoglu, Mehmet N; Clarke, Aaron M; Herzog, Michael H; Ögmen, Haluk

2016-05-01

We investigated how the visual system selects a reference frame for the perception of motion. Two concentric arcs underwent circular motion around the center of the display, where observers fixated. The outer (target) arc's angular velocity profile was modulated by a sine wave midflight whereas the inner (reference) arc moved at a constant angular speed. The task was to report whether the target reversed its direction of motion at any point during its motion. We investigated the effects of spatial and figural factors by systematically varying the radial and angular distances between the arcs, and their relative sizes. We found that the effectiveness of the reference frame decreases with increasing radial- and angular-distance measures. Drastic changes in the relative sizes of the arcs did not influence motion reversal thresholds, suggesting no influence of stimulus form on perceived motion. We also investigated the effect of common velocity by introducing velocity fluctuations to the reference arc as well. We found no effect of whether or not a reference frame has a constant motion. We examined several form- and motion-based metrics, which could potentially unify our findings. We found that a motion-based nearest vector metric can fully account for all the data reported here. These findings suggest that the selection of reference frames for motion processing does not result from a winner-take-all process, but instead, can be explained by a field whose strength decreases with the distance between the nearest motion vectors regardless of the form of the moving objects.

Low-mode internal tides and balanced dynamics disentanglement in altimetric observations: Synergy with surface density observations

NASA Astrophysics Data System (ADS)