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1

Home Run or Wild Pitch? Assessing the Economic Impact of Major League Baseball's All-Star Game  

Microsoft Academic Search

Major League Baseball has rewarded cities that build new baseball stadiums with the chance to host the All-Star Game. Although the league asserts a significant boost to metropolitan economies due to the game, are these economic impact estimates published by the league credible? In two separate economic impact models, the authors find that All-Star Games since 1973 are actually associated

Robert A. Baade; Victor A. Matheson

2001-01-01

2

After-School All-Stars: Providing Structured Health and Physical Activity Programs in Urban Environments  

ERIC Educational Resources Information Center

|Physical education time has been reduced or even eliminated in middle and high schools in favor of more time for standardized test preparation, especially in urban schools and inner cities. One way to replace the time lost is by providing it after school as part of a comprehensive program. After-School All-Stars (ASAS) is such a program,…

Thompson, Walter R.

2009-01-01

3

After-School All-Stars: Providing Structured Health and Physical Activity Programs in Urban Environments  

ERIC Educational Resources Information Center

Physical education time has been reduced or even eliminated in middle and high schools in favor of more time for standardized test preparation, especially in urban schools and inner cities. One way to replace the time lost is by providing it after school as part of a comprehensive program. After-School All-Stars (ASAS) is such a program, networked…

Thompson, Walter R.

2009-01-01

4

Sodium laser guide star results at the Lick Observatory  

SciTech Connect

Results of return signal level and guide star spot size for a sodium laser guide star recently installed at the Lick Observatory are presented. Operational characteristics of frequency stability, amplitude stability, and pointing accuracy are discussed.

Friedman, H.; Erbert, G.; Kuklo, T. [and others

1995-10-01

5

The Tax Benefits of Hosting the Super Bowl and the MLB All-Star Game: The Houston Experience  

Microsoft Academic Search

This study adds to our knowledge of the effects of mega-events like Super Bowls and Major League Baseball All-Star games by looking specifically at a long time-series of monthly sales tax revenues to assess the impact of these events on the host city’s revenue. The analysis indicates that sales tax revenues in Houston may be statistically significantly higher as a

Dennis Coates

2006-01-01

6

Measurements of the Lick Observatory Sodium Laser Guide Star  

SciTech Connect

The Lick Observatory guide star laser has provided a beacon sufficient to close the adaptive optics loop and produce corrected images during runs in 1996 and 1997. This report summarizes measurements of the wavefront quality of the outgoing beam, photoreturn signal from the sodium beacon, and radiance distribution of the guide star on the sky, and follows with an analysis of the impact of the laser on adaptive optics system performance.

Gavel, D. T., LLNL

1998-03-01

7

Synthetic Lick Indices and Detection of ?-Enhanced Stars  

NASA Astrophysics Data System (ADS)

Synthetic Lick indices computed with solar scaled abundances and with ?-element enhancement are presented and compared with predictions from both theoretical computations (Tripicco & Bell; Thomas, Maraston, & Bender; Barbuy et al.) and empirical fitting functions (de Freitas Pacheco). We propose selected combinations of indices capable of singling out ?-enhanced stars without requiring previous knowledge of their main atmospheric parameters. By applying this approach to the 460 stars in the Worthey et al. catalog, we detected a list of 82 candidate ?-enhanced stars. The confirmation of ?-enhancement was obtained by searching the literature for individual element abundance determinations from high-resolution spectroscopy for a subsample of 34 stars. Preliminary discussion of the properties of the detected ?-enhanced stars with respect to their [Fe/H] values and kinematics is presented.

Franchini, M.; Morossi, C.; Di Marcantonio, P.; Malagnini, M. L.; Chavez, M.; Rodriguez-Merino, L.

2004-01-01

8

Lick Saturn-Voyager Reference Star Catalogue (Klemola+, 1979)  

NASA Astrophysics Data System (ADS)

The Lick Saturn-Voyager Reference Star Catalogue was prepared for purposes of determining up-to-date, reasonably accurate, equatorial coordinates for reference stars in a band of sky against which cameras of the Voyager spacecraft were aligned for observations in the region of Saturn during the flyby. The requirements were a surface density of about three reference stars per observation frame of 24 sq.arcmin of the cameras - somewhat greater that the SAO (Smithsonian Astrophsyical Observatory Staff 1966) and the AGK3 (Dieckvoss et al. 1975) densities - and a positional accuracy +/- 0.5". Visual magnitudes were also required. The completed catalog contains 4551 stars in the right ascension range 12h 40min to 14h 12min, declination zones +02deg. to -09deg. Mean errors of the positions, as derived from least squares solutions against the Perth 70 Catalogue (Hoeg and von der Heide 1976), are about 0.25"; however, individual residuals for some bright and excessively faint stars are as high as 0.5" to 1.0". The accidental error of one measurement, as deduced from a tabular histogram given in the original catalog publication (referenced below), is about 0.09". Apparent photographic and visual magnitudes were derived from iris photometer measurements, visual magnitude being approximated from a derived color-index relation using UBV stars selected from the USNO photoelectric catalog (Blanco et al. 1968) and extended with Perth 70 stars. The resulting magnitudes appear to have mean errors of at least 0.2mag - 0.3mag for the brighter stars (visual magnitude < 10mag) and uncertainties can be as much as 0.5mag for the fainter stars. The magnitudes are considered to be only approximate, especially on the faint end, because of a lack of photoelectric standards there. For additional information concerning the observations and reductions, the original publication (available from A. R. Klemola) should be consulted. (1 data file).

Klemola, A. R.; Taraji, H.; Ocampo, A.

1995-05-01

9

Performance of laser guide star adaptive optics at Lick Observatory  

SciTech Connect

A sodium-layer laser guide star adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use on the 3-meter Shane telescope at Lick Observatory. The system is based on a 127-actuator continuous-surface deformable mirror, a Hartmann wavefront sensor equipped with a fast-framing low-noise CCD camera, and a pulsed solid-state-pumped dye laser tuned to the atomic sodium resonance line at 589 nm. The adaptive optics system has been tested on the Shane telescope using natural reference stars yielding up to a factor of 12 increase in image peak intensity and a factor of 6.5 reduction in image full width at half maximum (FWHM). The results are consistent with theoretical expectations. The laser guide star system has been installed and operated on the Shane telescope yielding a beam with 22 W average power at 589 nm. Based on experimental data, this laser should generate an 8th magnitude guide star at this site, and the integrated laser guide star adaptive optics system should produce images with Strehl ratios of 0.4 at 2.2 {mu}m in median seeing and 0.7 at 2.2 {mu}m in good seeing.

Olivier, S.S.; An, J.; Avicola, K. [and others

1995-07-19

10

Lick Jupiter-Voyager Reference Star Catalogue (Klemola+ 1978)  

NASA Astrophysics Data System (ADS)

The catalog was prepared for purposes of determining up-to-date, reasonably accurate equatorial coordinates for reference stars in a band of sky against which cameras of the Voyager spacecraft were aligned for observations of Jovian satellites during the Jupiter flyby. The catalog contains accurate equatorial coordinates for equinox 1950.0, epoch 1978.27, photographic and visual magnitudes, AGK3 identifications and proper motions for 4983 stars. All of the reference stars are in the range 6h00m to 8h04m in right ascension (1950), declination zones +16 to +23 degrees, and 8h31m to 8h57m, zones +08 to +14 degrees. Mean errors of the positions are about 0.4 second of arc. Introduction The Lick Jupiter-Voyager Reference Star Catalogue. Klemola et al. (1978) was prepared for purposes of determining up-to-date, reasonably accurate, equatorial coordinates for reference stars in a band of sky against which cameras of the Voyager spacecraft were aligned for observations of Jovian satellites during the Jupiter flyby. The requirements were a surface density of three to four reference stars per observation frame of 24 sq. arcmin. of the cameras - somewhat greater than that provided by the AGK3 catalog (Dieckvoss et al. 1975) - and a positional accuracy approximately 0.5. Visual magnitudes were also required. The completed catalog contains 4983 stars in the right ascension ranges 6h00m to 8h04m, declination zones +16 deg. to +23 deg., and 8h31m to 8h57m, declination zones +08 deg. to +14 deg.. Mean errors of the positions, as derived from least squares solutions against the AGK3 reference stars, are about 0.4"; however, individual residuals are fairly numerous in the range 0.6" to 0.8" with some in the range 1.0" to 1.3" The accidental error of one measurement, as deduced from a tabular histogram given in the original catalog publication (referenced below), is about 0.11". Apparent photographic and visual magnitudes were derived from iris photometer measurements, m(v). being approximated from a derived color-index relation using the AGK3 reference stars. The resulting magnitudes appear to have mean errors of at least 0.2 mag while very blue and very red stars (C.I..le.0 mag, and C.I..ge.1.5, respectively) are less certain. The magnitudes are considered to be only approximate (residuals of approximately 0.5 mag are fairly common). For additional information concerning the observations and reductions, the original publication (available from A. R. Klemola) should be consulted. A copy of this document should be transmitted to any recipient of the machine-readable catalog. (1 data file).

Klemola, A. R.; Morabito, L.

1996-04-01

11

Lick adaptive optics survey searching for low-mass companions to young, nearby stars  

Microsoft Academic Search

Using the Shane 3 meter telescope at Lick Observatory, we surveyed 102 nearby young stars with the near-infrared adaptive optics system. Young stars were targetted in order to increase the sensitivity to low-mass companions. Of these 102 stars, 44 had at least one other source in the field of view with separations ranging from 0.4\\

Q. M. Konopacky; B. A. Macintosh; A. M. Ghez; B. Zuckerman; D. Kaisler; I. Song

2002-01-01

12

Improved performance of the laser guide star adaptive optics system at Lick Observatory  

SciTech Connect

Results of experiments with the laser guide star adaptive optics system on the 3-meter Shane telescope at Lick Observatory have demonstrated a factor of 4 performance improvement over previous results. Stellar images recorded at a wavelength of 2 {micro}m were corrected to over 40% of the theoretical diffraction-limited peak intensity. For the previous two years, this sodium-layer laser guide star system has corrected stellar images at this wavelength to {approx}10% of the theoretical peak intensity limit. After a campaign to improve the beam quality of the laser system, and to improve calibration accuracy and stability of the adaptive optics system using new techniques for phase retrieval and phase-shifting diffraction interferometry, the system performance has been substantially increased. The next step will be to use the Lick system for astronomical science observations, and to demonstrate this level of performance with the new system being installed on the 10-meter Keck II telescope.

An, J R; Avicola, K; Bauman, B J; Brase, J M; Campbell, E W; Carrano, C; Cooke, J B; Freeze, G J; Friedman, H W; Max, C E; Gates, E L; Gavel, D T; Kanz, V K; Kuklo, T C; Macintosh, B A; Newman, M J; Olivier, S S; Pierce, E L; Waltjen, K E; Watson, A

1999-07-20

13

Initial results from the Lick Observatory Laser Guide Star Adaptive Optics System  

SciTech Connect

A prototype adaptive optics system has been installed and tested on the 3 m Shane telescope at Lick Observatory. The adaptive optics system performance, using bright natural guide stars, is consistent with expectations based on theory. A sodium-layer laser guide star system has also been installed and tested on the Shane telescope. Operating at 15 W, the laser system produces a 9th magnitude guide star with seeing-limited size at 589 nm. Using the laser guide star, the adaptive optics system has reduced the wavefront phase variance on scales above 50 cm by a factor of 4. These results represent the first continuous wavefront phase correction using a sodium-layer laser guide star. Assuming tip-tilt is removed using a natural guide star, the measured control loop performance should produce images with a Strehl ratio of 0.4 at 2.2 {mu}m in 1 arc second seeing. Additional calibration procedures must be implemented in order to achieve these results with the prototype Lick adaptive optics system.

Olivier, S.S.; An, J.; Avicola, K. [and others

1995-11-08

14

Cartoon All-Stars to the Rescue. Joint Hearing before the Senate Committee on the Judiciary and the House Committee on the Judiciary on An Entertaining Way of Enlightening Children about the Dangers of Substance Abuse. One Hundred First Congress, Second Session.  

ERIC Educational Resources Information Center

|This document presents witness testimony and supplemental materials from a Congressional hearing called to examine Cartoon All-Stars to the Rescue, a cartoon designed to teach children about the danger of substance abuse. Opening statements are included by Senator Joseph Biden, Jr., chairman of the Senate Judiciary Committee, and by Senators…

Congress of the U.S., Washington, DC. House Committee on the Judiciary.

15

First significant image improvement from a sodium-layer laser guide star adaptive optics system at Lick Observatory  

SciTech Connect

Atmospheric turbulence severely limits the resolution of ground-based telescopes. Adaptive optics can correct for the aberrations caused by the atmosphere, but requires a bright wavefront reference source in close angular proximity to the object being imaged. Since natural reference stars of the necessary brightness are relatively rare, methods of generating artificial reference beacons have been under active investigation for more than a decade. In this paper, we report the first significant image improvement achieved using a sodium-layer laser guide star as a wavefront reference for a high- order adaptive optics system. An artificial beacon was created by resonant scattering from atomic sodium in the mesosphere, at an altitude of 95 km. Using this laser guide star, an adaptive optics system on the 3 m Shane Telescope at Lick Observatory produced a factor of 2.4 increase in peak intensity and a factor of 2 decrease in full width at half maximum of a stellar image, compared with image motion compensation alone. The Strehl ratio when using the laser guide star as the reference was 65% of that obtained with a natural guide star, and the image full widths at half maximum were identical, 0.3 arc sec, using either the laser or the natural guide star. This sodium-layer laser guide star technique holds great promise for the world`s largest telescopes. 24 refs., 4 figs., 1 tab.

Olivier, S.S.; Max, C.E.; Friedman, H.W.; An, J.; Avicola, K.; Beeman, B.V.; Bissinger, H.D.; Brase, J.M.; Erbert, G.V.; Gavel, D.T.; Kanz, K.; Macintosh, B.; Neeb, K.P.; Waltjen, K.E.

1997-07-14

16

Stellar parameters, ages and distances in F,G,K stars from spectra analysis via Lick/SDSS indices  

NASA Astrophysics Data System (ADS)

Examples of stellar parameter, age, and distance estimates from spectra analyses based on comparison of observed and synthetic spectral indices are presented. We use the new synthetic library of spectral feature indices, Lick/SDSS, computed from "ad hoc" synthetic spectra to fully exploit the content of the spectroscopic SDSS-DR7 stellar database. This system is well suited to derive homogeneous and self-consistent estimates of atmospheric parameter values, Teff , log g, [Fe/H], and to study alpha-element abundances in F, G, and K stars. Then, spectroscopic distances and ages can be obtained via a Bayesian approach by using theoretical isochrones. Eventually, hints on the membership of each stars to one of the different Galactic components can be derived by studing its galactic stellar orbit using the Galactic potential by Johnston et al. (1996). In this way we attempt to take into account possible stellar migration in order to evaluate the difference between current and birthplace positions.

Franchini, Mariagrazia; Morossi, Carlo; di Marcantonio, Paolo; Malagnini, Maria Lucia; Chavez, Miguel; Venturi, Fulvia; Pinamonti, Matteo

2012-01-01

17

"Stars should henceforth register themselves": astrophotography at the early Lick Observatory.  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to explain how apparently contradictory aims were pursued, by exploring the collaboration between Lick Observatory astronomers and a group of commercial engravers in the production of astronomical photographs in the late 1890s and early 1900s. The author begins with a brief introduction to photomechanical printing technology. Next, he describes how astronomers chose one printing method over another, and what their relationships with printers were like. The author then examines astronomical aesthetics, the standards by which photographs were judged, and the effects astronomers sought in reproductions of pictures.

Pang, A. S.-K.

1997-06-01

18

Lick sodium laser guide star: performance during the 1998 LGS observing campaign  

SciTech Connect

The performance of a sodium laser guide star adaptive optics system depends crucially on the characteristics of the laser guide star in the sodium layer. System performance is quite sensitive to sodium layer spot radiance, that is, return per unit sterradian on the sky, hence we have been working to improve projected beam quality via improvements to the laser and changes to the launched beam format. The laser amplifier was reconfigured to a ''bounce-beam'' geometry, which considerably improves wavefront quality and allows a larger round instead of square launch beam aperture. The smaller beacon makes it easier to block the unwanted Rayleigh light and improves the accuracy of Hartmann sensor wavefront measurements in the A0 system. We present measurements of the beam quality and of the resulting sodium beacon and compare to similar measurements from last year.

Bauman, B; Friedman, H; Gavel, D T

1999-07-19

19

The Lick-Carnegie Survey: A New Two-planet System around the Star HD 207832  

NASA Astrophysics Data System (ADS)

Keck/HIRES precision radial velocities of HD 207832 indicate the presence of two Jovian-type planetary companions in Keplerian orbits around this G star. The planets have minimum masses of Msin i = 0.56 M Jup and 0.73 M Jup, with orbital periods of ~162 and ~1156 days, and eccentricities of 0.13 and 0.27, respectively. Strömgren b and y photometry reveals a clear stellar rotation signature of the host star with a period of 17.8 days, well separated from the period of the radial velocity variations, reinforcing their Keplerian origin. The values of the semimajor axes of the planets suggest that these objects have migrated from the region of giant planet formation to closer orbits. In order to examine the possibility of the existence of additional (small) planets in the system, we studied the orbital stability of hypothetical terrestrial-sized objects in the region between the two planets and interior to the orbit of the inner body. Results indicated that stable orbits exist only in a small region interior to planet b. However, the current observational data offer no evidence for the existence of additional objects in this system.

Haghighipour, Nader; Butler, R. Paul; Rivera, Eugenio J.; Henry, Gregory W.; Vogt, Steven S.

2012-09-01

20

GMOS Calibration to the Lick Index System  

NASA Astrophysics Data System (ADS)

In studies of unresolved stellar populations, age and metallicity are often the two most sought after quantities of interest. By comparing the stellar absorption features of unresolved systems to those of the Lick standard stars, ages and metallicities of the underlying stellar populations can be determined. However, care must be taken in calibrating spectra to the Lick system, as the original Lick spectra were not flux calibrated. In order to properly calibrate unresolved spectra, it is necessary to observe many of the original Lick standard stars and derive offsets to the standard system. This project has collected and reduced all available Lick observations performed with the Gemini Multi-Object Spectrograph (GMOS). In addition, a new online database is being developed, in which the derived offsets and reduced spectra will eventually be available for download.

Mirocha, Jordan; Miller, B.; Trancho, G.

2010-01-01

21

THE LICK/SDSS LIBRARY. II. [Ca/Fe] AND [Mg/Fe] IN F, G, AND K STARS FROM SDSS-DR7  

SciTech Connect

We analyzed the spectra of 17,600 F, G, and K stars extracted from the seventh Sloan Digital Sky Survey Data Release (SDSS-DR7) database in order to derive ([{alpha}/Fe]), [Ca/Fe], and [Mg/Fe] ratios. Particular attention has been devoted to estimating homogeneous and self-consistent atmospheric parameter values, T{sub eff}, log g, and [Fe/H], by comparing synthetic and observational Lick/SDSS indices. We present results for the sub-sample of more than 4000 spectra whose overall quality allowed us to derive fairly accurate stellar atmospheric parameter values and, therefore, reliable abundance ratios. A Monte Carlo approach was adopted to evaluate both the errors in the observational Lick/SDSS indices and in the derived parameter estimates. The analysis of the trends of [Ca/Fe] and [Mg/Fe] versus [Fe/H] pointed out that (1) the [Ca/Fe] and [Mg/Fe] ratios increase with decreasing [Fe/H] with different slopes reaching maximum average levels of +0.25 and +0.40 dex at [Fe/H] {approx_equal} -1.75, respectively; (2) our sample contains, at a given [Fe/H], stars characterized by significantly different amounts of {alpha}-enhancement, thus belonging to different Galactic populations; and (3) the analyzed sample shows a predominance of thick disk stars for [Fe/H] > - 0.5 and the presence of stars belonging to the 'high-{alpha}' halo population for -2.0 < [Fe/H] <-0.5.

Franchini, M.; Morossi, C.; Di Marcantonio, P.; Malagnini, M. L. [INAF-Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste (Italy); Chavez, M., E-mail: franchini@oats.inaf.it, E-mail: morossi@oats.inaf.it, E-mail: dimarcan@oats.inaf.it, E-mail: malagnini@oats.inaf.it, E-mail: mchavez@inaoep.mx [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro 1, 72840 Tonantzintla, Puebla (Mexico)

2011-04-01

22

Lick Saturn-Voyager reference star catalogue (Klemola, Taraji, and Ocampo 1979): Documentation for the machine-readable version  

NASA Astrophysics Data System (ADS)

The machine readable version of the catalog, as it is currently being distributed from the Astronomical Data Center, is described. The catalog contains accurate equatorial coordinates for 4551 stars in a band of sky against which cameras of the Voyager spacecraft were pointed for observations in the region of Saturn during the flyby. All of the reference stars are in the range 12h 40m to 14h 12m in right ascension (1950) and +02 to -09 degs in declination. Mean errors of the positions are about 0.25 sec.

Warren, Wayne H., Jr.

1990-02-01

23

ALLStars: Overcoming Multi-Survey Selection Bias using Crowd-Sourced Active Learning  

NASA Astrophysics Data System (ADS)

Developing a multi-survey time-series classifier presents several challenges. One problem is overcoming the sample selection bias which arises when the instruments or observing cadences differ between the training and testing datasets. In this case, the probabilistic distributions characterizing the sources in the training survey dataset differ from the source distributions in the other survey, resulting in poor results when a classifier is naively applied. To resolve this, we have developed the ALLStars active learning framework which allows us to bootstrap a classifier onto a new survey using a small set of optimally chosen sources which are then presented to users for manual classification. Several iterations of this crowd-sourcing process results in a significantly improved classifier. Using this procedure, we have built a variable star light-curve classifier using OGLE, Hipparcos, and ASAS survey data.

Starr, D. L.; Richards, J. W.; Brink, H.; Miller, A. A.; Bloom, J. S.; Butler, N. R.; James, J. B.; Long, J. P.

2012-09-01

24

Performance of adaptive optics at Lick Observatory  

SciTech Connect

A prototype adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use at Lick Observatory. This system is based on an ITEX 69-actuator continuous-surface deformable mirror, a Kodak fast-framing intensified CCD camera, and a Mercury VME board containing four Intel i860 processors. The system has been tested using natural reference stars on the 40-inch Nickel telescope at Lick Observatory yielding up to a factor of 10 increase in image peak intensity and a factor of 6 reduction in image full width at half maximum (FWHM). These results are consistent with theoretical expectations. In order to improve performance, the intensified CCD camera will be replaced by a high-quantum-efficiency low-noise fast CCD camera built for LLNL by Adaptive Optics Associates using a chip developed by Lincoln Laboratory, and the 69-actuator deformable mirror will be replaced by a 127-actuator deformable mirror developed at LLNL. With these upgrades, the system should perform well in median seeing conditions on the 120-inch Shane telescope for observing wavelengths longer than {approximately}1 {mu}m and using natural reference stars brighter than m{sub R} {approximately} 10 or using the laser currently being developed at LLNL for use at Lick Observatory to generate a sodium-layer reference star.

Olivier, S.S.; An, J.; Avicola, K. [Lawrence Livermore National Lab., CA (United States)] [and others

1994-03-01

25

Lick NPM2 Catalog (Hanson+ 2003)  

NASA Astrophysics Data System (ADS)

The NPM2 Catalog is the second part of the Lick Northern Proper Motion (NPM) program to measure absolute proper motions, on an inertial system defined by distant galaxies, for nearly 400,000 stars over a blue apparent magnitude range from 8 to 18. There are 1246 6x6degree fields in the NPM survey (to declination -23 degrees). The NPM2 Catalog covers the 28% of the northern sky lying near the plane of the the Milky Way and contains some 232,000 stars in the 347 NPM fields remaining after the 1993 NPM1 Catalog (149,000 stars in 899 fields away from the Milky Way). Each NPM field was photographed with the 51cm Carnegie Double Astrograph at two epochs between 1947 and 1988. The mean first and second epochs are 1950 and 1977; the average epoch difference is 27 years. The first-epoch plates were taken in the blue only; both blue and yellow plates were taken at the second epoch. For NPM2, the plates were scanned by the Precision Measuring Machine (PMM) at the US Naval Observatory, Flagstaff. From the PMM scans, 120,000 faint (B>14) stars were chosen anonymously for the NPM astrometric reductions and for statistical studies of stellar motions. The NPM2 catalog also contains 92,000 bright (B<14) positional reference stars, mostly from the Tycho-2 Catalogue, and 35,000 stars chosen for astronomical interest from Klemola's "Lick Input Catalog of Special Stars". (These categories overlap). Details of the NPM2 star selection, data reductions, and catalog compilation will be presented in a paper being prepared for the Astronomical Journal. The completed version of the NPM2 Catalog totals 232,062 stars from all 347 NPM2 fields; it supersedes the September 2002 preliminary version (295 fields). Together with the NPM1 Catalog (Cat. I/199, or http://www.ucolick.org/~npm/NPM1/) the NPM2 Catalog completes the Lick Northern Proper Motion program after more than a half-century of work by three generations of Lick Observatory astronomers. The NPM2 catalog gives J2000 positions computed for the catalog epoch 2000, and is ordered in 108 one-degree declination zones from +83 degrees to -23 degrees. Following the convention of the NPM1 catalog, each NPM2 star has an NPM2 "name" (e.g. +83.0001) reflecting the declination zone and a running number in right ascension order within the zone. The NPM2 Catalog is also available as 108 separate files, one for each declination zone from +83 degrees (z+83n) to -23 degrees (z-23n), from http://www.ucolick.org/~npm/NPM2/zones/ Each star's entry includes the absolute proper motion and blue (B) magnitude. For 98.5% of the stars the B-V color is also given. Other data given for each star are: the original mean epoch, a stellar class code, the number of NPM fields on which the star was measured, and discrepancy flags for proper motion, and photometry. Tycho-2 numbers are given for the primary positional reference stars (40% of NPM2); for these stars the Tycho B,V photometry, transformed to Johnson B and B-V, has been averaged with the NPM2 photographic photometry, with appropriate weights. ACRS and Hipparcos numbers are also given for NPM2 stars selected from those catalogs. The RMS precision of the NPM2 individual proper motions is about 0.6"/cent (6mas/yr) in each coordinate, comparable to the NPM1 errors. The NPM2 relative proper motions in each field were reduced to absolute (ICRS system) using an average of 370 Tycho-2 stars per NPM2 field. Magnitude-dependent systematic errors for the brightest (8

Hanson, R. B.; Klemola, A. R.; Jones, B. F.; Monet, D. G.

2003-05-01

26

Progress with the lick adaptive optics system  

SciTech Connect

Progress and results of observations with the Lick Observatory Laser Guide Star Adaptive Optics System are presented. This system is optimized for diffraction-limited imaging in the near infrared, 1-2 micron wavelength bands. We describe our development efforts in a number of component areas including, a redesign of the optical bench layout, the commissioning of a new infrared science camera, and improvements to the software and user interface. There is also an ongoing effort to characterize the system performance with both natural and laser guide stars and to fold this data into a refined system model. Such a model can be used to help plan future observations, for example, predicting the point-spread function as a function of seeing and guide star magnitude.

Gavel, D T; Olivier, S S; Bauman, B; Max, C E; Macintosh, B

2000-03-01

27

The Lick-Carnegie Exoplanet Survey: A 3.1 M_Earth Planet in the Habitable Zone of the Nearby M3V Star Gliese 581  

Microsoft Academic Search

We present 11 years of HIRES precision radial velocities (RV) of the nearby\\u000aM3V star Gliese 581, combining our data set of 122 precision RVs with an\\u000aexisting published 4.3-year set of 119 HARPS precision RVs. The velocity set\\u000anow indicates 6 companions in Keplerian motion around this star. Differential\\u000aphotometry indicates a likely stellar rotation period of ~94 days

Steven S. Vogt; R. Paul Butler; Eugenio J. Rivera; Nader Haghighipour; Gregory W. Henry; Michael H. Williamson

2010-01-01

28

THE LICK-CARNEGIE EXOPLANET SURVEY: A 3.1 M{sub +} PLANET IN THE HABITABLE ZONE OF THE NEARBY M3V STAR GLIESE 581  

Microsoft Academic Search

We present 11 years of HIRES precision radial velocities (RVs) of the nearby M3V star Gliese 581, combining our data set of 122 precision RVs with an existing published 4.3-year set of 119 HARPS precision RVs. The velocity set now indicates six companions in Keplerian motion around this star. Differential photometry indicates a likely stellar rotation period of 94 days

Steven S. Vogt; E. J. Rivera; R. Paul Butler; N. Haghighipour; Gregory W. Henry; Michael H. Williamson

2010-01-01

29

The Lick-Carnegie Exoplanet Survey: A 3.1 M ? Planet in the Habitable Zone of the Nearby M3V Star Gliese 581  

Microsoft Academic Search

We present 11 years of HIRES precision radial velocities (RVs) of the nearby M3V star Gliese 581, combining our data set of 122 precision RVs with an existing published 4.3-year set of 119 HARPS precision RVs. The velocity set now indicates six companions in Keplerian motion around this star. Differential photometry indicates a likely stellar rotation period of ~94 days

Steven S. Vogt; R. Paul Butler; E. J. Rivera; N. Haghighipour; Gregory W. Henry; Michael H. Williamson

2010-01-01

30

The Lick-Carnegie Exoplanet Survey: A Saturn-Mass Planet in the Habitable Zone of the Nearby M4V Star HIP 57050  

Microsoft Academic Search

Precision radial velocities (RV) from Keck\\/HIRES reveal a Saturn-mass planet orbiting the nearby M4V star HIP 57050. The planet has a minimum mass of Msin i ~ 0.3 M J, an orbital period of 41.4 days, and an orbital eccentricity of 0.31. V-band photometry reveals a clear stellar rotation signature of the host star with a period of 98 days,

Nader Haghighipour; Steven S. Vogt; R. Paul Butler; Eugenio J. Rivera; Greg Laughlin; Stefano Meschiari; Gregory W. Henry

2010-01-01

31

THE LICK-CARNEGIE EXOPLANET SURVEY: A 3.1 M{sub +} PLANET IN THE HABITABLE ZONE OF THE NEARBY M3V STAR GLIESE 581  

SciTech Connect

We present 11 years of HIRES precision radial velocities (RVs) of the nearby M3V star Gliese 581, combining our data set of 122 precision RVs with an existing published 4.3-year set of 119 HARPS precision RVs. The velocity set now indicates six companions in Keplerian motion around this star. Differential photometry indicates a likely stellar rotation period of {approx}94 days and reveals no significant periodic variability at any of the Keplerian periods, supporting planetary orbital motion as the cause of all the RV variations. The combined data set strongly confirms the 5.37-day, 12.9-day, 3.15-day, and 67-day planets previously announced by Bonfils et al., Udry et al., and Mayor et al.. The observations also indicate a fifth planet in the system, GJ 581f, a minimum-mass 7.0 M{sub +} planet orbiting in a 0.758 AU orbit of period 433 days, and a sixth planet, GJ 581g, a minimum-mass 3.1 M{sub +} planet orbiting at 0.146 AU with a period of 36.6 days. The estimated equilibrium temperature of GJ 581g is 228 K, placing it squarely in the middle of the habitable zone of the star and offering a very compelling case for a potentially habitable planet around a very nearby star. That a system harboring a potentially habitable planet has been found this nearby, and this soon in the relatively early history of precision RV surveys, indicates that {eta}{sub +}, the fraction of stars with potentially habitable planets, is likely to be substantial. This detection, coupled with statistics of the incompleteness of present-day precision RV surveys for volume-limited samples of stars in the immediate solar neighborhood, suggests that {eta}{sub +} could well be on the order of a few tens of percent. If the local stellar neighborhood is a representative sample of the galaxy as a whole, our Milky Way could be teeming with potentially habitable planets.

Vogt, Steven S.; Rivera, E. J. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Butler, R. Paul [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States); Haghighipour, N. [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Henry, Gregory W.; Williamson, Michael H. [Tennessee State University, Center of Excellence in Information Systems, 3500 John A. Merritt Blvd., Box 9501, Nashville, TN 37209-1561 (United States)

2010-11-01

32

The Lick-Carnegie Exoplanet Survey: A 3.1 M ? Planet in the Habitable Zone of the Nearby M3V Star Gliese 581  

NASA Astrophysics Data System (ADS)

We present 11 years of HIRES precision radial velocities (RVs) of the nearby M3V star Gliese 581, combining our data set of 122 precision RVs with an existing published 4.3-year set of 119 HARPS precision RVs. The velocity set now indicates six companions in Keplerian motion around this star. Differential photometry indicates a likely stellar rotation period of ~94 days and reveals no significant periodic variability at any of the Keplerian periods, supporting planetary orbital motion as the cause of all the RV variations. The combined data set strongly confirms the 5.37-day, 12.9-day, 3.15-day, and 67-day planets previously announced by Bonfils et al., Udry et al., and Mayor et al.. The observations also indicate a fifth planet in the system, GJ 581f, a minimum-mass 7.0 M ? planet orbiting in a 0.758 AU orbit of period 433 days, and a sixth planet, GJ 581g, a minimum-mass 3.1 M ? planet orbiting at 0.146 AU with a period of 36.6 days. The estimated equilibrium temperature of GJ 581g is 228 K, placing it squarely in the middle of the habitable zone of the star and offering a very compelling case for a potentially habitable planet around a very nearby star. That a system harboring a potentially habitable planet has been found this nearby, and this soon in the relatively early history of precision RV surveys, indicates that ??, the fraction of stars with potentially habitable planets, is likely to be substantial. This detection, coupled with statistics of the incompleteness of present-day precision RV surveys for volume-limited samples of stars in the immediate solar neighborhood, suggests that ?? could well be on the order of a few tens of percent. If the local stellar neighborhood is a representative sample of the galaxy as a whole, our Milky Way could be teeming with potentially habitable planets.

Vogt, Steven S.; Butler, R. Paul; Rivera, E. J.; Haghighipour, N.; Henry, Gregory W.; Williamson, Michael H.

2010-11-01

33

Recent Science and Engineering Results with the Laser Guidestar Adaptive Optics System at Lick Observatory  

SciTech Connect

The Lick Observatory laser guide star adaptive optics system has undergone continual improvement and testing as it is being integrated as a facility science instrument on the Shane 3 meter telescope. Both Natural Guide Star (NGS) and Laser Guide Star (LGS) modes are now used in science observing programs. We report on system performance results as derived from data taken on both science and engineering nights and also describe the newly developed on-line techniques for seeing and system performance characterization. We also describe the future enhancements to the Lick system that will enable additional science goals such as long-exposure spectroscopy.

Gavel, D T; Gates, E; Max, C; Olivier, S; Bauman, B; Pennington, D; Macintosh, B; Patience, J; Brown, C; Danforth, P; Hurd, R; Severson, S; Lloyd, J

2002-10-17

34

Lick Northern Proper Motion: NPM1 Ref. Galaxies (Klemola+ 1987)  

NASA Astrophysics Data System (ADS)

The Lick Northern Proper Motion (NPM) program measured proper motions, positions, and photographic photometry for some 149,000 stars (NPM1 Catalog) covering the sky outside the Milky Way north of declination 23 degrees. The NPM1 proper motions were measured with respect to an absolute reference frame defined by some 50,000 faint galaxies (mostly 16 < B < 18 mag). The rms position errors for the NPM1 reference galaxies average 0.2 arcsec. The rms errors for the B magnitudes average 0.25 mag. More complete descriptive information is available in the ASCII or LaTeX documentation written by R.B. Hanson (UCO/Lick Obs.). (1 data file).

Klemola, A. R.; Hanson, R. B.; Jones, B. F.

1994-11-01

35

Lick Northern Proper Motion Program: NPM1 Catalog (Klemola+ 1987)  

NASA Astrophysics Data System (ADS)

The NPM1 catalog is the first part of the Lick Northern Proper Motion (NPM) program to measure absolute proper motions, on an inertial system defined by some 50,000 faint galaxies, for some 300,000 stars over a blue apparent magnitude range from 8 to 18. There are 1246 6-degree by 6-degree fields in the NPM survey (to declination -23 degrees). The NPM1 catalog covers the 72% of the northern sky lying outside the Milky Way and contains some 149,000 stars from measures in 899 of the 1246 NPM fields. A second catalog (NPM2) will cover the NPM Milky Way fields. The Yale Southern Proper Motion (SPM) program will complete the southern sky. Each NPM field was photographed at two epochs between 1947 and 1988. The mean first and second epochs are 1950 and 1977; the average epoch difference is 27 years. The first-epoch plates were taken in the blue only; both blue and yellow plates were taken at the second epoch. Some 94000 stars were chosen anonymously for the NPM astrometric reductions and for statistical studies of stellar motions. In addition, the NPM1 catalog contains some 28000 positional reference stars, and some 27000 stars were chosen from the Lick Input Catalog of Special Stars (ICSS). Positions are given for equinox B1950 and computed epoch 1950. Each star's entry includes the absolute proper motion and blue magnitude. For 97% of the stars the color is also given. Other data given for each star are: the original mean epoch, a stellar class code, the number of NPM fields measured, and discrepancy flags for position, proper motion, and photometry. Finally, as an additional identification, the AGK3 (north) or SAO (south) number (if any) is given. The rms errors of the NPM absolute proper motions are about 0.5"/cent in each coordinate. The rms position errors at the catalog epoch 1950 average about 0.15" in each coordinate. The rms errors for the NPM photographic photometry average about 0.2 mag in B, and 0.15 mag in B-V. More complete descriptive information is available in the ASCII or LaTeX documentation written by A.R. Klemola, R.B. Hansen, and R.B. Jones (UCO/Lick Obs.) (1 data file).

Klemola, A. R.; Hanson, R. B.; Jones, B. F.

1994-11-01

36

Distribution of Lick Indices in the Globular Cluster NGC 2808  

NASA Astrophysics Data System (ADS)

We have analyzed low resolution spectra for a large sample ( 200) of red giant branch (RGB) stars in the Galactic globular cluster NGC 2808 for indications of bimodality with respect to Lick indices and radial dispersion. Target stars were observed in nine fields over 5 nights in March 2010 with the Blanco 4m telescope and Hydra multi--object positioner and bench spectrograph located at Cerro Tololo Inter--American Observatory. The full wavelength coverage spans from 3900--8200 A; for nights 1 and 2, and from 4500--6950 A; for nights 3, 4, and 5. The low resolution data ( 500 for nights 1 and 2, 1200 for nights 3, 4, and 5; 70) were used to measure radial velocities (RVs) and to determine cluster membership. RVs were measured with the IRAF task xcsao using stars with known radial RVs included in our observed fields as templates. Template candidates were taken from Cacciari et al. (2004) and Carretta et al. (2006), and cross--matched by RA and Dec to stars in our sample. A conservative approach was adopted when including stars as cluster members, with RV= 101.9 ± 7.17 km s-1 (?=2.83). Indexf was employed to measure 12 Lick indices, with particular attention to CN1, CN2 and Na. The peak distribution of these indices appears to be correlated in stars 2.5--3.5 arc minutes from the cluster center. The correlation becomes less apparent in stars outside this radius.

O'Connell, Julia

2012-01-01

37

[Is being licked by dogs not dirty?].  

PubMed

Being licked by pet dogs is frequently a common advice in articles for the uninitiated. An overview is given about the special antibacterial and wound healing properties of human and canine saliva. New developments in the human area are presumably assigned to dog saliva. Because of the presence of a quite different mouth flora including various potential zoonotic pathogens, it is strictly not advised to let dogs lick the wounds or face of the human. PMID:23025205

Overgaauw, Paul; van Knapen, Frans

2012-09-01

38

Lick NPM2 Catalog Preliminary Version (Hanson+ 2002)  

NASA Astrophysics Data System (ADS)

The NPM2 Catalog is the second part of the Lick Northern Proper Motion (NPM) program to measure absolute proper motions, on an inertial system defined by some 50,000 faint galaxies, for nearly 400,000 stars over a blue apparent magnitude range from 8 to 18. There are 1246 6x6degree fields in the NPM survey (to declination -23°). The NPM2 Catalog covers the 28% of the northern sky lying near the plane of the the Milky Way and contains some 230,000 stars in the 347 NPM fields remaining after the 1993 NPM1 Catalog (149,000 stars in 899 fields away from the Milky Way). Each NPM field was photographed with the 51 cm Carnegie Double Astrograph at two epochs between 1947 and 1988. The mean first and second epochs are 1950 and 1977; the average epoch difference is 27 years. The first-epoch plates were taken in the blue only; both blue and yellow plates were taken at the second epoch. For NPM2, the plates were scanned by the Precision Measuring Machine (PMM) at the US Naval Observatory, Flagstaff. From the PMM scans, some 120,000 faint (B>14) stars were chosen anonymously for the NPM astrometric reductions and for statistical studies of stellar motions. In addition, the NPM2 catalog contains some 80,000 bright (B<14) positional reference stars, mostly from the Tycho-2 Catalogue, and some 35,000 stars chosen for astronomical interest from Klemola's "Lick Input Catalog of Special Stars" (ICSS). Details of the NPM2 star selection, data reductions, and catalog compilation will be presented in a paper being prepared for the Astronomical Journal. The present version (September 2002) of the NPM2 Catalog contains 196,639 stars from 295 of the 347 NPM2 fields (85%). The remaining 52 fields, in the Summer Milky Way from -02 to -23°, are now being processed, and will be added to the catalog in 2003. Together with the NPM1 Catalog (J2000 version at http://www.ucolick.org/~npm/NPM1/) the NPM2 Catalog completes the Lick Northern Proper Motion program after more than a half-century of work by three generations of Lick Observatory astronomers. The NPM2 catalog gives J2000 positions computed for the catalog epoch 2000, and is in the form of 108 one-degree declination zone files (e.g. z+83n) from +83 to -23°. Following the convention of the NPM1 catalog, each NPM2 star has an NPM2 "name" (e.g. +83.0001) reflecting the declination zone and a running number in right ascension order within the zone. Each star's entry includes the absolute proper motion and blue (B) magnitude. For 98.5% of the stars the B-V color is also given. Other data given for each star are: the original mean epoch, a stellar class code, the number of NPM fields on which the star was measured, and discrepancy flags for proper motion, and photometry. Tycho-2 numbers are given for the primary positional reference stars (40% of NPM2); for these stars the Tycho B,V photometry, transformed to Johnson B and B-V, is listed in preference to the NPM2 photographic photometry. ACRS and Hipparcos numbers are also given for NPM2 stars selected from those catalogs. The RMS errors of the NPM2 absolute proper motions are about 0.6"/centy (6mas/yr) in each coordinate, comparable to the NPM1 errors. The RMS position errors at the NPM2 catalog epoch 2000 average about 0.2" (200mas) in each coordinate, due mostly to the accumulated proper motion error from original plate epochs (average 1968) to 2000. The pure positional errors at the original epochs average 0.08" (80mas) in each coordinate. The RMS errors for the NPM photographic photometry average about 0.18mag in B, and 0.20mag in B-V. We thank the National Science Foundation for its long-term support of the NPM program. The NPM2 phase was supported by NSF grants AST-9530632 and AST-9988105. We thank the Yale Southern Proper Motion group (W. van Altena, I. Platais, and T. Girard) for their help in developing software to process the PMM plate scans. (1 data file).

Hanson, R. B.; Klemola, A. R.; Jones, B. F.; Monet, D. G.

2002-09-01

39

Lick Northern Proper Motion Program: NPM1 Catalog (Klemola+ 1987)  

NASA Astrophysics Data System (ADS)

The NPM1 catalog is the first part of the Lick Northern Proper Motion (NPM) program to measure absolute proper motions, on an inertial system defined by some 50,000 faint galaxies, for some 300,000 stars over a blue apparent magnitude range from 8 to 18. There are 1246 6-degree by 6-degree fields in the NPM survey (to declination -23 degrees). The NPM1 catalog covers the 72% of the northern sky lying outside the Milky Way and contains some 149,000 stars from measures in 899 of the 1246 NPM fields. A second catalog (NPM2) will cover the NPM Milky Way fields. The Yale Southern Proper Motion (SPM) program will complete the southern sky. Each NPM field was photographed at two epochs between 1947 and 1988. The mean first and second epochs are 1950 and 1977; the average epoch difference is 27 years. The first-epoch plates were taken in the blue only; both blue and yellow plates were taken at the second epoch. Some 94000 stars were chosen anonymously for the NPM astrometric reductions and for statistical studies of stellar motions. In addition, the NPM1 catalog contains some 28000 positional reference stars, and some 27000 stars were chosen from the Lick Input Catalog of Special Stars (ICSS). The previous version of the NPM1 Catalog (I/199) deposited with the data centers (ADC and CDS) gives positions for equinox B1950 and computed epoch 1950, and is in one data file (148,940 lines) concatenating the 114 one-degree declination zones from +90 degrees to -23 degrees. Each star has an NPM1 "name" reflecting the declination zone and a running number in right ascension order within the zone. The present J2000 version gives the NPM1 positions transformed into the J2000 system and updated to the epoch 2000 using the NPM1 proper motions. The proper motions have been rotated into the J2000 coordinate system. The J2000 NPM1 Catalog is ordered in zones from +90 degrees to -23 degrees, and within each zone, the stars are sorted in right ascension order. To avoid "renaming" stars, the B1950 NPM1 "names" were retained, but the user must note that these no longer strictly reflect the declination zone and right ascension order in the J2000 NPM1 Catalog. The J2000 NPM1 Catalog is also available as 114 separate files, one for each declination zone from +90 degrees (z+90j) to -23 degrees (z-23j), from http://www.ucolick.org/~npm/NPM1/zones/ Each star's entry includes the absolute proper motion and blue magnitude. For 97% of the stars the color is also given. Other data given for each star are: the original mean epoch, a stellar class code, the number of NPM fields measured, and discrepancy flags for position, proper motion, and photometry. Finally, as an additional identification, the AGK3 (north) or SAO (south) number (if any) is given. The rms errors of the NPM absolute proper motions are about 0.5"/cent in each coordinate. The rms position errors at the catalog epoch 1950 average about 0.15" in each coordinate. The rms errors for the NPM photographic photometry average about 0.2 mag in B, and 0.15 mag in B-V. More complete information is available in the PostScript documentation for the 1993 (B1950) NPM1 Catalog (npm1b.ps), written by R.B. Hanson. We thank the National Science Foundation for its continued support of the NPM program. Recent work was supported by NSF grant AST-9530632. Current work is supported by NSF grant AST-9988105. (1 data file).

Klemola, A. R.; Hanson, R. B.; Jones, B. F.

2000-05-01

40

Conceptual design for a user-friendly adaptive optics system at Lick Observatory  

SciTech Connect

In this paper, we present a conceptual design for a general-purpose adaptive optics system, usable with all Cassegrain facility instruments on the 3 meter Shane telescope at the University of California`s Lick Observatory located on Mt. Hamilton near San Jose, California. The overall design goal for this system is to take the sodium-layer laser guide star adaptive optics technology out of the demonstration stage and to build a user-friendly astronomical tool. The emphasis will be on ease of calibration, improved stability and operational simplicity in order to allow the system to be run routinely by observatory staff. A prototype adaptive optics system and a 20 watt sodium-layer laser guide star system have already been built at Lawrence Livermore National Laboratory for use at Lick Observatory. The design presented in this paper is for a next- generation adaptive optics system that extends the capabilities of the prototype system into the visible with more degrees of freedom. When coupled with a laser guide star system that is upgraded to a power matching the new adaptive optics system, the combined system will produce diffraction-limited images for near-IR cameras. Atmospheric correction at wavelengths of 0.6-1 mm will significantly increase the throughput of the most heavily used facility instrument at Lick, the Kast Spectrograph, and will allow it to operate with smaller slit widths and deeper limiting magnitudes. 8 refs., 2 figs.

Bissinger, H.D.; Olivier, S.; Max, C.

1996-03-08

41

Drinking spout orifice size affects licking behavior in inbred mice.  

PubMed

Using a lickometer, we assessed the effect of drinking spout orifice size on the licking behavior of inbred mice [C57BL/6J, SWR/J, 129P3/J and DBA/2J]. Animals licked from drinking spout sipper tubes that had what were defined as either a large (2.7 mm) or a small (1.5 mm) orifice. Mice took approximately twice as many licks from a stationary single small orifice drinking spout than when licking from a spout with a large orifice during separate 30-min sessions. However, their total intake volume was approximately the same. We calculated that mice received a mean of 0.55 muL per lick from the drinking tubes with a small orifice and a mean of 1.15 muL per lick from the drinking tubes with a large orifice. Thus, the animals appear to have regulated their fluid intake by proportionally adjusting their licking as a function of the lick volume. On average, this regulation occurred through modulation of the size of licking bursts and not their frequency. However, strain differences in compensation strategy were observed. When licking was restricted to a series of 5-s trials in a 30-min brief access test session, the smaller orifice size increased the range of responsiveness that was expressed. Mice increased their average licks per trial by 20% and took 60% more trials when licking from a spout with a small orifice. Interestingly, when the orifice size was quasi-randomly varied within a brief access session, licking was greater from large orifice drinking spouts, suggesting that water delivered from the two orifice sizes differs in its reinforcement efficacy. These findings demonstrate that drinking spout orifice size can significantly influence experimental outcomes in licking tests involving mice and care should be taken in controlling this variable in testing the effects of taste or other factors on ingestive behavior. PMID:16083923

Dotson, Cedrick D; Spector, Alan C

2005-08-01

42

An efficient auction based ticket booking scheme for NBA all-star event championship  

Microsoft Academic Search

The Basketball is uniquely American game and most popular in this country and now getting popularity in worldwide. National Basketball Association(NBA)is the major basket ball league conducting basketball matches event of every year in the month of february. In a basketball match, k tickets are available and more than k people give demand for a ticket to watch the match.

Sajal Mukhopadhyay; Pramod Mane; D. Ghosh

2010-01-01

43

Analysing globular cluster observations. Models and analysis tools for Lick/IDS indices  

NASA Astrophysics Data System (ADS)

We have extended our evolutionary synthesis code, galev, to include Lick/IDS absorption-line indices for both simple and composite stellar population models (star clusters and galaxies), using polynomial fitting functions. We present a mathematically advanced Lick index analysis tool (LINO) for the determination of the ages and metallicities of globular clusters (CGs). An extensive grid of galev models for the evolution of star clusters at various metallicities over a Hubble time is compared to observed sets of Lick indices of varying completeness and precision. A dedicated ?^2-minimisation procedure selects the best model including 1 ? uncertainties on age and metallicity. We discuss the age and metallicity sensitivities of individual indices and show that these sensitivities themselves depend on age and metallicity; thus, we extend Worthey's (1994) concept of a "metallicity sensitivity parameter" for an old stellar population at solar metallicity to younger clusters of different metallicities. We find that indices at low metallicity are generally more age sensitive than at high metallicity. Our aim is to provide a robust and reliable tool for the interpretation of star-cluster spectra becoming available from 10 m class telescopes in a large variety of galaxies - metal-rich & metal-poor, starburst, post-burst, and dynamically young. We test our analysis tool using observations from various authors for Galactic and M 31 GCs, for which reliable age and metallicity determinations are available in the literature, and discuss to what extent the observational availability of various subsets of Lick indices affects the results. For M 31 GCs, we discuss the influence of non-solar abundance ratios on our results. All models are accessible from our website, http://www.astro.physik.uni-goettingen.de/~galev/

Lilly, T.; Alvensleben, U. Fritze-V.

2006-10-01

44

A. A. Michelson's Jovian Galilean-Satellite Interferometer at Lick Observatory in 1891  

NASA Astrophysics Data System (ADS)

Albert A. Michelson, America's first Nobel laureate in physics, measured the angular diameter of the red supergiant star Betelgeuse in 1920 with Francis G. Pease, using the 100-inch Mount Wilson reflector as the basis of his stellar interferometer. But he had first published the concept in 1890 and tested it on celestial objects with a telescope at Lick Observatory in 1891. He used its 12-inch refractor to measure the angular diameters of the four Galilean satellites of Jupiter, assisted at the telescope by W. W. Campbell, then a young astronomer who had just joined the Lick staff. Edward S. Holden, the Lick director, had invited Michelson to come to Mount Hamilton and use its telescopes as a guest observer. Michelson had first tried and proved his method on artificial circular disks in his laboratory at Clark University, Worcester, Mass., using a 2-inch "glass." Then in 1889 and 1890 he hoped to test it at Harvard College Observatory, but apparently the telescope or the atmospheric conditions did not work out. At Lick he did achieve success, and his measured angular diameters were nearer to the true values we know from close-up space measurements of today than those of any of the top visual observers of the time. Correspondence in the Lick Archives shows that Michelson intended to come back there to use its big 36-inch refractor to improve the measurements, but he never did so. Selections from Michelson's published papers and photographs of him, the telescope, and the instrument will be posted.

Osterbrock, D. E.

2004-12-01

45

Lick Adaptive Optics Observations of Early-Type Galaxy Centers  

Microsoft Academic Search

We have observed the centers of 10 nearby early-type galaxies using the Lick Adaptive Optics (AO) system in the H-band. The Lick AO system gives us near diffraction-limited performance in the H-band with a resolution of 0.\\

L. M. Raschke; P. Jonsson; S. Severson; S. M. Faber; B. A. Macintosh

2000-01-01

46

Differential control of operant and consummatory licking in rats.  

PubMed

The failure of rats to optimize their behavior when drinking from two retractable spouts available for single licks was analyzed. The rats were trained in an apparatus where the contacted spout was withdrawn after completion of a lick and the other spout was presented. After 5 days of such forced spout alternation training the animals continued to emit 2.7 instead of the optimum 1.0 lick per spout presentation (LPSP). With water available in one spout only the average LPSP at the empty spout dropped to 1.2 and increased to 3.6 at the water containing spout. It is argued that the operant licks at the dry spout approach the ideal value of 1.0 LPSP whereas the number of LPSPs at the water spout is increased by the consummatory nature of licking triggered by the presence of water in the oral cavity. PMID:2234493

Mamedov, Z; Bures, J

1990-07-31

47

Update on Optical Design of Adaptive Optics System at Lick Observatory  

SciTech Connect

In 1999, we presented our plan to upgrade the adaptive optics (AO) system on the Lick Observatory Shane telescope (3m) from a prototype instrument pressed into field service to a facility instrument. This paper updates the progress of that plan and details several important improvements in the alignment and calibration of the AO bench. The paper also includes a discussion of the problems seen in the original design of the tip/tilt (t/t) sensor used in laser guide star mode, and how these problems were corrected with excellent results.

Bauman, B J; Gavel, D T; Waltjen, K E; Freeze, G J; Hurd, R L; Gates, E I; Max, C E; Olivier, S S; Pennington, D M

2001-07-31

48

Laser Guide Star Based Astrophysics at Lick Observatory.  

National Technical Information Service (NTIS)

The resolution of ground-based telescopes is typically limited to 1 second of arc because of the blurring effects of atmospheric turbulence. Adaptive optics (AO) technology senses and corrects for the optical distortions due to turbulence hundreds of time...

C. Max D. Gavel H. Friedman S. Olivier B. Macintosh J. Brase K. Avicola S. Gibbard J. An

2000-01-01

49

IRCAL: the infrared camera for adaptive optics at Lick Observatory  

Microsoft Academic Search

We describe the design, characterization and performance of the IR Camera for Adaptive Optics at Lick (IRCAL). IRCAL is a 1-2.5 micron camera optimized for use with the LLNL Lick adaptive optics system on the Shane 3 m telescope. Using diamond-turned gold-coated optics, the camera provides high efficiency diffraction limited imaging throughout the near- IR. IRCAL incorporates optimizations for obtaining

James P. Lloyd; Michael C. Liu; Bruce A. Macintosh; Scott A. Severson; William T. Deich; James R. Graham

2000-01-01

50

library of Lick\\/IDS for binaries (Zhang+, 2006)  

Microsoft Academic Search

Using evolutionary population synthesis, we present 13 refined absorption-line indices defined by the Lick Observatory Image Dissector Scanner (Lick\\/IDS) system for an extensive set of instantaneous-burst binary stellar populations (BSPs) at high resolution (~0.3{AA}), and 38 indices at intermediate resolution (3{AA}). The ages of the populations are at an interval of 1Gyr in the range 115 Gyr, and the metallicities

F. Zhang; L. Li

2007-01-01

51

Library of Lick\\/IDS indices for binaries (Zhang+, 2006)  

Microsoft Academic Search

Using evolutionary population synthesis, we present 13 refined absorption-line indices defined by the Lick Observatory Image Dissector Scanner (Lick\\/IDS) system for an extensive set of instantaneous-burst binary stellar populations (BSPs) at high resolution (~0.3{AA}), and 38 indices at intermediate resolution (3{AA}). The ages of the populations are at an interval of 1Gyr in the range 115 Gyr, and the metallicities

F. Zhang; L. Li

2007-01-01

52

75 FR 9530 - FM TABLE OF ALLOTMENTS, French Lick, Indiana, and Irvington, Kentucky.  

Federal Register 2010, 2011, 2012, 2013

...RM-11412] FM TABLE OF ALLOTMENTS, French Lick, Indiana, and Irvington, Kentucky...modifies the license of Station WFLQ(FM), French Lick, Indiana, to specify operation...the licensee of Station WFLQ(FM), French Lick, Indiana, to show cause why...

2010-03-03

53

Proposed Multiconjugate Adaptive Optics Experiment at Lick Observatory  

SciTech Connect

While the theory behind design of multiconjugate adaptive optics (MCAO) systems is growing, there is still a paucity of experience building and testing such instruments. We propose using the Lick adaptive optics (AO) system as a basis for demonstrating the feasibility/workability of MCAO systems, testing underlying assumptions, and experimenting with different approaches to solving MCAO system issues.

Bauman, B J; Gavel, D T; Flath, L M; Hurd, R L; Max, C E; Olivier, S S

2001-08-15

54

Licking and liking: The assessment of hedonic responses in rodents  

Microsoft Academic Search

Affective processes are a key determinant of behaviour: At its simplest, liked stimuli are approached while disliked stimuli are avoided. Although assessing hedonic responses in nonverbal animals can be difficult, one relatively tractable approach relies on detailed analyses of rodents' consummatory behaviour. Rodents typically produce rhythmic sets of licks that can be grouped into clusters on the basis of the

Dominic M. Dwyer

2012-01-01

55

Licking and liking: The assessment of hedonic responses in rodents  

Microsoft Academic Search

Affective processes are a key determinant of behaviour: at its simplest, liked stimuli are approached while disliked stimuli are avoided. Although assessing hedonic responses in non-verbal animals can be difficult, one relatively tractable approach relies on detailed analyses of rodents’ consummatory behaviour. Rodents typically produce rhythmic sets of licks that can be grouped into clusters on the basis of the

Dominic M. Dwyer

2011-01-01

56

FIVE PLANETS AND AN INDEPENDENT CONFIRMATION OF HD 196885Ab FROM LICK OBSERVATORY  

SciTech Connect

We present time series Doppler data from Lick Observatory that reveal the presence of long-period planetary companions orbiting nearby stars. The typical eccentricity of these massive planets are greater than the mean eccentricity of known exoplanets. HD 30562b has Msin i = 1.29 M {sub Jup}, with semimajor axis of 2.3 AU and eccentricity 0.76. The host star has a spectral type F8V and is metal rich. HD 86264b has Msin i = 7.0 M {sub Jup}, a {sub rel} = 2.86 AU, an eccentricity e = 0.7 and orbits a metal-rich, F7V star. HD 87883b has Msin i = 1.78 M {sub Jup}, a {sub rel} = 3.6 AU, e = 0.53 and orbits a metal-rich K0V star. HD 89307b has Msin i = 1.78 M {sub Jup}, a {sub rel} = 3.3 AU, e = 0.24 and orbits a G0V star with slightly subsolar metallicity. HD 148427b has Msin i = 0.96 M {sub Jup}, a {sub rel} = 0.93 AU, eccentricity of 0.16 and orbits a metal rich K0 subgiant. We also present velocities for a planet orbiting the F8V metal-rich binary star, HD 196885A. The planet has Msin i = 2.58 M {sub Jup}, a {sub rel} = 2.37 AU, and orbital eccentricity of 0.48, in agreement with the independent discovery by Correia et al.

Fischer, Debra; Isaacson, Howard; Giguere, Matt; McCarthy, Chris [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States); Driscoll, Peter [Department of Earth and Planetary Science, Johns Hopkins University, Baltimore, MD (United States); Marcy, Geoffrey W.; Howard, Andrew; Peek, Katherine [Department of Astronomy, University of California, Berkeley, Berkeley, CA (United States); Valenti, Jeff [Space Telescope Science Institute, Baltimore, MD (United States); Wright, Jason T. [Cornell University, Ithaca, NY (United States); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Blvd., Box 9501, Nashville, TN 37209 (United States); Johnson, John Asher, E-mail: fischer@stars.sfsu.ed [NSF Astronomy and Astrophysics Postdoctoral Fellow, Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

2009-10-01

57

Stars  

NSDL National Science Digital Library

This section of the Windows to the Universe web site provides information and images about stars including star statistics, and a star gallery. Windows to the Universe is a user-friendly learning system pertaining to the Earth and Space sciences. The objective of this project is to develop an innovative and engaging web site that spans the Earth and Space sciences and includes a rich array of documents, including images, movies, animations, and data sets that explore the Earth and Space sciences and the historical and cultural ties between science, exploration and the human experience. Links at the top of each page allow users to navigate between beginner, intermediate and advanced levels.

Johnson, Roberta

2000-07-01

58

Library of Lick/IDS indices for binaries (Zhang+, 2006)  

NASA Astrophysics Data System (ADS)

Using evolutionary population synthesis, we present 13 refined absorption-line indices defined by the Lick Observatory Image Dissector Scanner (Lick/IDS) system for an extensive set of instantaneous-burst binary stellar populations (BSPs) at high resolution (~0.3{AA}), and 38 indices at intermediate resolution (3{AA}). The ages of the populations are at an interval of 1Gyr in the range 115 Gyr, and the metallicities are in the range 0.004-0.03. These indices are obtained by two methods: (i) using the empirical fitting functions (FFs method); (ii) measured directly from the synthetic spectra (DC method). Together with our previous paper, a data base of Lick/IDS spectral absorption-line indices for BSPs at high and intermediate resolutions is provided. This set of indices includes 21 indices of Worthey et al. (1994, Cat. ), four Balmer indices defined by Worthey & Ottaviani (1997, Cat. ), and 13 indices with the new passband definitions of Trager et al. (1998, Cat. , hereafter T98. (6 data files).

Zhang, F.; Li, L.

2007-04-01

59

library of Lick/IDS for binaries (Zhang+, 2006)  

NASA Astrophysics Data System (ADS)

Using evolutionary population synthesis, we present 13 refined absorption-line indices defined by the Lick Observatory Image Dissector Scanner (Lick/IDS) system for an extensive set of instantaneous-burst binary stellar populations (BSPs) at high resolution (~0.3{AA}), and 38 indices at intermediate resolution (3{AA}). The ages of the populations are at an interval of 1Gyr in the range 115 Gyr, and the metallicities are in the range 0.004-0.03. These indices are obtained by two methods: (i) using the empirical fitting functions (FFs method); (ii) measured directly from the synthetic spectra (DC method). Together with our previous paper, a data base of Lick/IDS spectral absorption-line indices for BSPs at high and intermediate resolutions is provided. This set of indices includes 21 indices of Worthey et al. (1994, Cat. ), four Balmer indices defined by Worthey & Ottaviani (1997, Cat. ), and 13 indices with the new passband definitions of Trager et al. (1998, Cat. , hereafter T98. (6 data files).

Zhang, F.; Li, L.

2007-04-01

60

Stellar Companions to Stars with Planets  

Microsoft Academic Search

A combination of high-resolution and wide-field imaging reveals two binary stars and one triple star system among the sample of the first 11 stars with planets detected by radial velocity variations. High-resolution speckle or adaptive optics (AO) data probe subarcsecond scales down to the diffraction limit of the Keck 10 m or the Lick 3 m, and direct images or

J. Patience; R. J. White; A. M. Ghez; C. McCabe; I. S. McLean; J. E. Larkin; L. Prato; Sungsoo S. Kim; J. P. Lloyd; M. C. Liu; J. R. Graham; B. A. Macintosh; D. T. Gavel; C. E. Max; B. J. Bauman; S. S. Olivier; P. Wizinowich; D. S. Acton

2002-01-01

61

Flux-calibrated stellar population models of Lick absorption-line indices with variable element abundance ratios  

NASA Astrophysics Data System (ADS)

We present new stellar population models of Lick absorption-line indices with variable element abundance ratios. The models are based on our new calibrations of absorption-line indices with stellar parameters derived from the MILES stellar library. The key novelty compared to our previous models is that they are now available at the higher spectral resolution of MILES (2.5 Å full width at half-maximum) and flux calibrated, hence not tied anymore to the Lick/IDS system. This is essential for the interpretation of galaxy spectra where calibration stars are not available, such as large galaxy redshift surveys or other high-redshift observations. We note that the MILES resolution appears to be comparable to Sloan Digital Sky Survey (SDSS) resolution, so that our models can be applied to SDSS data without any corrections for instrumental spectral resolution. For the first time we provide random errors for the model predictions based on the uncertainties in the calibration functions and the underlying stellar parameter estimates. We show that random errors are small except at the edges of the parameter space (high/low metallicities and young ages ?1 Gyr) where the stellar library is undersampled. We calibrate the base model for the parameters age, metallicity and ?/Fe ratio with galactic globular cluster and galaxy gradient data. We discuss two model flavours with different input stellar evolutionary tracks from the Frascati and Padova groups. The new model release now includes abundance variations of the elements C, N, Mg, Na, Si, Ca, Ti, Cr and Fe. The individual elements that are best accessible with these models and the standard set of Lick absorption features are C, N, Mg, Ca, Ti and Fe. The model data are available at ˜thomasd.

Thomas, Daniel; Maraston, Claudia; Johansson, Jonas

2011-04-01

62

Sizing up Asteroids at Lick Observatory with Adaptive Optics  

NASA Astrophysics Data System (ADS)

Using the Shane 3 meter telescope with adaptive optics at Lick Observatory, we have determined the triaxial dimensions and rotational poles of five asteroids, 3 Juno, 4 Vesta, 16 Psyche, 87 Sylvia, and 324 Bamberga. Parametric blind deconvolution was applied to images obtained mostly at 2.5 microns in 2004 and 2006. This is the first time Bamberga’s pole has been determined, and the results for the other four asteroids are in agreement with the analysis of decades of lightcurves by others. The techniques developed here to find sizes, shapes, and poles, in only one or two nights, can be applied to smaller asteroids that are resolved with larger telescopes.

Drummond, Jack D.; Christou, J.

2006-12-01

63

Parrot behavior at a Rio Manu (Peru) clay lick: temporal patterns, associations, and antipredator responses  

Microsoft Academic Search

Although eating clay at licks (a form of geophagy) has been described, there are few behavioral data on temporal patterns, social interactions, species associations, or reactions to potential predators. We examined the behavior of nine species of macaws, parrots, and parakeets at the Machiguenga Ccolpa, a clay lick on the Rio Manu, Peru in the dry season. Three distinct mixed-species

Joanna Burger; Michael Gochfeld

2003-01-01

64

The Lick AGN Monitoring Project 2. Photometric Light Curves  

NASA Astrophysics Data System (ADS)

The Lick AGN Monitoring Project (LAMP) targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. In conjunction with the spectroscopic monitoring, we obtained broad-band B and V imaging observations on most nights between the months of February and May 2008. The sample of 13 objects was divided between four telescopes: the 30-inch Katzman Automatic Imaging Telescope (KAIT), the 2-meter Multicolor Active Galactic Nuclei Monitoring (MAGNUM) telescope, the Palomar 60-inch telescope, and the 32-inch Tenagra II telescope. In this talk, we will discuss the observational methods, the photometric measurements, the resultant light curves, and the variability characteristics of each object.

Walsh, Jonell; LAMP Collaboration

2009-01-01

65

Adaptive optics at Lick Observatory: System architecture and operations  

SciTech Connect

We will describe an adaptive optics system developed for the 1 meter Nickel and 3 meter Shane telescopes at Lick Observatory. Observing wavelengths will be in the visible for the 1 meter telescope and in the near IR on the 3 meter. The adaptive optics system design is based on a 69 actuator continuous surface deformable mirror and a Hartmann wavefront sensor equipped with an intensified CCD framing camera. The system has been tested at the Cassegrain focus of the 1 meter telescope where the subaperture size is 12.5 cm. The wavefront control calculations are performed on a four processor single board computer controlled by a Unix-based system. We will describe the optical system and give details of the wavefront control system design. We will present predictions of the system performance and initial test results.

Brase, J.M.; An, J.; Avicola, K. [and others

1994-03-01

66

Nutrition or Detoxification: Why Bats Visit Mineral Licks of the Amazonian Rainforest  

PubMed Central

Many animals in the tropics of Africa, Asia and South America regularly visit so-called salt or mineral licks to consume clay or drink clay-saturated water. Whether this behavior is used to supplement diets with locally limited nutrients or to buffer the effects of toxic secondary plant compounds remains unclear. In the Amazonian rainforest, pregnant and lactating bats are frequently observed and captured at mineral licks. We measured the nitrogen isotope ratio in wing tissue of omnivorous short-tailed fruit bats, Carollia perspicillata, and in an obligate fruit-eating bat, Artibeus obscurus, captured at mineral licks and at control sites in the rainforest. Carollia perspicillata with a plant-dominated diet were more often captured at mineral licks than individuals with an insect-dominated diet, although insects were more mineral depleted than fruits. In contrast, nitrogen isotope ratios of A. obscurus did not differ between individuals captured at mineral lick versus control sites. We conclude that pregnant and lactating fruit-eating bats do not visit mineral licks principally for minerals, but instead to buffer the effects of secondary plant compounds that they ingest in large quantities during periods of high energy demand. These findings have potential implications for the role of mineral licks for mammals in general, including humans.

Voigt, Christian C.; Capps, Krista A.; Dechmann, Dina K. N.; Michener, Robert H.; Kunz, Thomas H.

2008-01-01

67

Nutrition or detoxification: why bats visit mineral licks of the Amazonian rainforest.  

PubMed

Many animals in the tropics of Africa, Asia and South America regularly visit so-called salt or mineral licks to consume clay or drink clay-saturated water. Whether this behavior is used to supplement diets with locally limited nutrients or to buffer the effects of toxic secondary plant compounds remains unclear. In the Amazonian rainforest, pregnant and lactating bats are frequently observed and captured at mineral licks. We measured the nitrogen isotope ratio in wing tissue of omnivorous short-tailed fruit bats, Carollia perspicillata, and in an obligate fruit-eating bat, Artibeus obscurus, captured at mineral licks and at control sites in the rainforest. Carollia perspicillata with a plant-dominated diet were more often captured at mineral licks than individuals with an insect-dominated diet, although insects were more mineral depleted than fruits. In contrast, nitrogen isotope ratios of A. obscurus did not differ between individuals captured at mineral lick versus control sites. We conclude that pregnant and lactating fruit-eating bats do not visit mineral licks principally for minerals, but instead to buffer the effects of secondary plant compounds that they ingest in large quantities during periods of high energy demand. These findings have potential implications for the role of mineral licks for mammals in general, including humans. PMID:18431492

Voigt, Christian C; Capps, Krista A; Dechmann, Dina K N; Michener, Robert H; Kunz, Thomas H

2008-04-23

68

Inefficient licking during forced spout alternation in rats: violation of the law of effect?  

PubMed

The efficiency of the neural control of licking was assessed in rats (n = 6) allowed 30-min daily access to water in a box equipped with two retractable drinking spouts. After completion of a photoelectrically monitored lick, the contacted spout was withdrawn by an electromechanical device which simultaneously made the other spout available at an adjacent wall opening. Although economy of behavior required the animals to lick at each spout only once, computer monitored licking showed that the rats emitted 2.9 +/- 0.2 and 2.5 +/- 0.1 licks per spout presentation (LPSP) on the first and fifth days of training, respectively. The transition time between spouts and the interlick interval were not significantly changed. Separation of the spouts by a vertical partition extending 24 mm into the box prolonged the transition time and increased LPSP to 3.9 and 3.3 on Days 1 and 4 of training, respectively. These values were not changed when the length of the partition was increased to 40 mm. The failure of rats to maximize reward by emitting single licks probably reflects limited control of the generator of licking and/or the tendency to avoid its frequent switching on and off. PMID:3575448

Mamedov, Z; Hernandez-Mesa, N; Bures, J

1987-01-01

69

Keepers of the double stars  

NASA Astrophysics Data System (ADS)

Astronomers have long tracked double stars in efforts to find those that are gravitationally-bound binaries and then to determine their orbits. Early catalogues by the Herschels, Struves, and others began with their own discoveries. In 1906 court reporter and amateur astronomer Sherburne Wesley Burnham published a massive double star catalogue containing data from many observers on more than 13,000 systems. Lick Observatory astronomer Robert Grant Aitken produced a much larger catalogue in 1932 and coordinated with Robert Innes of Johannesburg, who catalogued the southern systems. Aitken maintained and expanded Burnham's records of observations on handwritten file cards, and eventually turned them over to the Lick Observatory, where astrometrist Hamilton Jeffers further expanded the collection and put all the observations on punched cards. With the aid of Frances M. "Rete" Greeby he made two catalogues: an Index Catalogue with basic data about each star, and a complete catalogue of observations, with one observation per punched card. He enlisted Willem van den Bos of Johannesburg to add southern stars, and together they published the Index Catalogue of Visual Double Stars, 1961.0. As Jeffers approached retirement he became greatly concerned about the disposition of the catalogues. He wanted to be replaced by another "double star man," but Lick Director Albert E. Whitford had the new 120-inch reflector, the world's second largest telescope, and he wanted to pursue modern astrophysics instead. Jeffers was vociferously opposed to turning over the card files to another institution, and especially against their coming under the control of Kaj Strand of the United States Naval Observatory. In the end the USNO got the files and has maintained the records ever since, first under Charles Worley, and, since 1997, under Brian Mason. Now called the Washington Double Star Catalog (WDS), it is completely online and currently contains more than 1,200,000 measures of more than 125,000 star systems.

Tenn, Joseph S.

2013-03-01

70

Conditioned lick behavior and evoked responses using whisker twitches in head restrained rats  

PubMed Central

To examine whisker barrel evoked response potentials in chronically implanted rats during behavioral learning with very fast response times, rats must be calm while immobilized with their head restrained. We quantified their behaviors during training with an ethogram and measured each individual animals’ progress over the training period. Once calm under restraint, rats were conditioned to differentiate between a reward and control whisker twitch, then provide a lick response when presented with the correct stimulus, rewarded by a drop of water. Rats produced the correct licking response (after reward whisker twitch), and learned not to lick after a control whisker was twitched. By implementing a high density 64 channel electrocorticogram (ECoG) electrode array, we mapped the barrel field of the somatosensory cortex with high spatial and temporal resolution during conditioned lick behaviors. In agreement with previous reports, we observe a larger evoked response after training, probably related to mechanisms of cortical plasticity.

Topchiy, Irina A.; Wood, Rachael M.; Peterson, BreeAnne; Navas, Jinna A.; Rojas, Manuel J.; Rector, David M.

2008-01-01

71

The effect of direct administration of drugs into the licking generator in rats  

Microsoft Academic Search

Spontaneous licking of thirsty rats was investigated under the effect of GYKI (an AMPA\\/kainate receptor antagonist) and of 2-amino-5-phosphonopentanoic acid (AP5, an NMDA receptor antagonist) applied intracranially into the central rhythm generator of licking. Adult Long Evans male rats were stereotaxically implanted with guiding cannulae aimed at the oral part of nucleus reticularis gigantocellularis (NRG). After a recovery (1 week

O Vajnerova; G Brozek

2002-01-01

72

Importance of natural licks for the mammals in Bornean inland tropical rain forests  

Microsoft Academic Search

An intensive camera-trapping study and a nutrient analysis were carried out to understand how natural licks are important\\u000a for mammals in inland tropical rain forests where soil cations are usually depleted. Using camera traps, we investigated the\\u000a fauna, food habits, and the frequency of visitation by species at five natural licks in the Deramakot forest reserve, Sabah,\\u000a Malaysia. All food-habit

Hisashi Matsubayashi; Peter Lagan; Noreen Majalap; Joseph Tangah; Jum Rafiah Abd. Sukor; Kanehiro Kitayama

2007-01-01

73

Coal handling\\/The Licking River Terminal: a showcase in coal handling  

Microsoft Academic Search

Oglebay Norton Co.'s new Licking River Terminal near Cincinnati is moving low-sulfur Kentucky coal onto barge fleets plying the Ohio River to serve electric power generating stations. The Louisville and Nashville Railroad hauls coal some 250 to 300 mi from the Harlan and the Hazard coalfields to the DeCoursey yard three miles from the Licking River Terminal, delivering the coal

Yewell

1978-01-01

74

The Fine Temporal Structure of the Rat Licking Pattern: What Causes the Variabiliy in the Interlick Intervals and How is it Affected by the Drinking Solution?  

PubMed

Licking is a repetitive behavior controlled by a central pattern generator. Even though interlick intervals (ILIs) within bursts of licks are considered fairly regular, the conditions that affect their variability are unknown. We analyzed the licking pattern in rats that licked water, 10% sucrose solution, or 10% ethanol solution, in 90-min recording sessions after 4h of water deprivation. The histograms of ILIs indicate that licking typically occurred at a preferred ILI of about 130-140ms with evidence of bimodal or multimodal distributions due to occasional licking failures. We found that the longer the pause between bursts of licks, the shorter was the first ILI of the burst. When bursts of licks were preceded by a pause >4 s, the ILI was the shortest (~110ms) at the beginning of the burst, and then it increased rapidly in the first few licks and slowly in subsequent licks. Interestingly, the first ILI of a burst of licks was not significantly different when licking any of the 3 solutions, but subsequent licks exhibited a temporal pattern characteristic of each solution. The rapid deceleration in intraburst licking rate was due to an increase from ~27ms to ~56ms in the tongue-spout contact duration while the intercontact interval was only slightly changed (80-90ms). Therefore, the contact duration seems to be the major factor that increases the variability in the ILIs and could be another means for the rat to adjust the amount of fluid ingested in each individual lick. PMID:23902635

Lin, Xiong Bin; Pierce, Dwight R; Light, Kim Edward; Hayar, Abdallah

2013-07-31

75

Taste Coding in the Nucleus of the Solitary Tract of the Awake, Freely Licking Rat  

PubMed Central

It is becoming increasingly clear that the brain processes sensory stimuli differently according to whether they are passively or actively acquired, and these differences can be seen early in the sensory pathway. In the nucleus of the solitary tract (NTS), the first relay in the central gustatory neuraxis, a rich variety of sensory inputs generated by active licking converge. Here we show that taste responses in the NTS reflect these interactions. Experiments consisted of recordings of taste-related activity in the NTS of awake rats as they freely licked exemplars of the five basic taste qualities (sweet, sour, salty, bitter, umami). Nearly all taste-responsive cells were broadly tuned across taste qualities. A subset responded to taste with long latencies (>1.0 s), suggesting the activation of extra-oral chemoreceptors. Analyses of the temporal characteristics of taste responses showed that spike timing conveyed significantly more information than spike count alone in almost half of NTS cells, as in anesthetized rats, but with less information per cell. In addition to taste-responsive cells, the NTS contains cells that synchronize with licks. Since the lick pattern per se can convey information, these cells may collaborate with taste-responsive cells to identify taste quality. Other cells become silent during licking. These latter “anti-lick” cells show a surge in firing rate predicting the beginning and signaling the end of a lick bout. Collectively, the data reveal a complex array of cell types in the NTS, only a portion of which include taste-responsive cells, which work together to acquire sensory information.

Roussin, Andre T.; D'Agostino, Alexandra E.; Fooden, Andrew M.; Victor, Jonathan D.; Di Lorenzo, Patricia M.

2012-01-01

76

Externally Dispersed Interferometry with the Lick Observatory Echelle Spectrograph  

NASA Astrophysics Data System (ADS)

We demonstrate stellar and solar measurements of full-bandwidth echelle spectra using an externally dispersed interferometer (EDI). Spectral resolution of ~120k has been obtained using the ~60k resolution CAT facility at the Lick Observatory. The EDI is a series combination of a fixed delay interferometer and a grating spectrograph that increases the spectrograph's effective resolution by factors of 2 to 3. EDI uses a heterodyning effect to shift the input spectrum's high spectral resolution information to lower spatial frequencies that are less sensitive to the resolution limit caused by the spectrograph slit size and by the Nyquist limit of the detector. The resolution-boosted spectra is obtained by numerically reversing the heterodyning effect and combining these data with the ordinary spectrum simultaneously acquired within the EDI data. The interferometer fringes imprinted on the spectrum are exactly periodic in frequency space and acts as a fiducial net that uniformly covers the entire echelle bandwidth. Instrumental distortions that deviate the stellar signal also deviate these fiducial fringes, so the measurement, in comparison to a classical echelle data, is extremely robust to beam profile errors. Our method uses a uniform-phase interferometer fringe at the spectrograph entrance slit. Therefore the spectrograph may use either a 2d-echelle or slit-imaging format. The EDI has applications in Doppler radial velocimetry and high resolution spectroscopy. Work was partially supported by CalSpace/Lockheed, and NASA SARA research grants NAG5-9091 and NAG5-3051. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Erskine, D. J.; Edelstein, J.

2002-12-01

77

Development of a flood-warning system and flood-inundation mapping in Licking County, Ohio  

USGS Publications Warehouse

Digital flood-inundation maps for selected reaches of South Fork Licking River, Raccoon Creek, North Fork Licking River, and the Licking River in Licking County, Ohio, were created by the U.S. Geological Survey (USGS), in cooperation with the Ohio Department of Transportation; U.S. Department of Transportation, Federal Highway Administration; Muskingum Watershed Conservancy District; U.S. Department of Agriculture, Natural Resources Conservation Service; and the City of Newark and Village of Granville, Ohio. The inundation maps depict estimates of the areal extent of flooding corresponding to water levels (stages) at the following USGS streamgages: South Fork Licking River at Heath, Ohio (03145173); Raccoon Creek below Wilson Street at Newark, Ohio (03145534); North Fork Licking River at East Main Street at Newark, Ohio (03146402); and Licking River near Newark, Ohio (03146500). The maps were provided to the National Weather Service (NWS) for incorporation into a Web-based flood-warning system that can be used in conjunction with NWS flood-forecast data to show areas of predicted flood inundation associated with forecasted flood-peak stages. As part of the flood-warning streamflow network, the USGS re-installed one streamgage on North Fork Licking River, and added three new streamgages, one each on North Fork Licking River, South Fork Licking River, and Raccoon Creek. Additionally, the USGS upgraded a lake-level gage on Buckeye Lake. Data from the streamgages and lake-level gage can be used by emergency-management personnel, in conjunction with the flood-inundation maps, to help determine a course of action when flooding is imminent. Flood profiles for selected reaches were prepared by calibrating steady-state step-backwater models to selected, established streamgage rating curves. The step-backwater models then were used to determine water-surface-elevation profiles for up to 10 flood stages at a streamgage with corresponding streamflows ranging from approximately the 50 to 0.2-percent chance annual-exceedance probabilities for each of the 4 streamgages that correspond to the flood-inundation maps. The computed flood profiles were used in combination with digital elevation data to delineate flood-inundation areas. Maps of Licking County showing flood-inundation areas overlain on digital orthophotographs are presented for the selected floods. The USGS also developed an unsteady-flow model for a reach of South Fork Licking River for use by the NWS to enhance their ability to provide advanced flood warning in the region north of Buckeye Lake, Ohio. The unsteady-flow model was calibrated based on data from four flooding events that occurred from June 2008 to December 2011. Model calibration was approximate due to the fact that there were unmeasured inflows to the river that were not able to be considered during the calibration. Information on unmeasured inflow derived from NWS hydrologic models and additional flood-event data could enable the NWS to further refine the unsteady-flow model.

Ostheimer, Chad J.

2012-01-01

78

Asymmetric response to directional selection for licking behavior of Drosophila melanogaster males.  

PubMed

Selection for high and low licking rate was carried out on courting males of a cage-population of Drosophila melanogaster for 21 generations. The males were tested against a standard female tester genotype in every generation. The low-scoring line responded linearly to selection, reaching a plateau after eight generations. The attempt to raise the licking rate above the level of the base population was not effective. The realized heritability of the L and H line over the first seven generations was 41.0 and 0.4%, respectively. From the fourth generation onward, the two lines differed significantly. Reciprocal crossing between the two lines indicated the absence of X-chromosome and maternal effects. There was no significant dominance. The selection for licking in males had no discernible effect on female sexual activity. H-line males mated significantly faster with standard females than L-line males. PMID:1590728

Welbergen, P; van Dijken, F R

1992-01-01

79

Hamilton Jeffers and the Double Star Catalogues  

NASA Astrophysics Data System (ADS)

Astronomers have long tracked double stars in efforts to find those that are gravitationally-bound binaries and then to determine their orbits. Court reporter and amateur astronomer Shelburne Wesley Burnham (1838-1921) published a massive double star catalogue containing more than 13,000 systems in 1906. The next keeper of the double stars was Lick Observatory astronomer Robert Grant Aitken (1864-1951), who produced a much larger catalogue in 1932. Aitken maintained and expanded Burnham’s records of observations on handwritten file cards, eventually turning them over to Lick Observatory astrometrist Hamilton Moore Jeffers (1893-1976). Jeffers further expanded the collection and put all the observations on punched cards. With the aid of Frances M. "Rete" Greeby (1921-2002), he made two catalogues: an Index Catalogue with basic data about each star, and a complete catalogue of observations, with one observation per punched card. He enlisted Willem van den Bos of Johannesburg to add southern stars, and they published the Index Catalogue of Visual Double Stars, 1961.0. As Jeffers approached retirement he became greatly concerned about the disposition of the catalogues. He wanted to be replaced by another "double star man," but Lick Director Albert E. Whitford (1905-2002) had the new 120-inch reflector, the world’s second largest telescope, and he wanted to pursue modern astrophysics instead. Jeffers was vociferously opposed to turning over the card files to another institution, and especially against their coming under the control of Kaj Strand of the U.S. Naval Observatory. In the end the USNO got the files and has maintained the records ever since, first under Charles Worley (1935-1997), and, since 1997, under Brian Mason. Now called the Washington Double Star Catalog (WDS), it is completely online and currently contains more than 1,000,000 measures of more than 100,000 pairs.

Tenn, Joseph S.

2013-01-01

80

New Analyses of Star-to-Star Abundance Variations among Bright Giants in the Mildly Metal-poor Globular Cluster M5  

Microsoft Academic Search

We present a chemical composition analysis of 36 giant stars in the mildly metal-poor (=-1.21) globular cluster M5 (NGC 5904). The analysis makes use of high-resolution data acquired for 25 stars at the Keck I telescope, as well as a reanalysis of the high-resolution spectra for 13 stars acquired for an earlier study at Lick Observatory. We employed two analysis

Inese I. Ivans; Robert P. Kraft; Christopher Sneden; Graeme H. Smith; R. Michael Rich; Matthew Shetrone

2001-01-01

81

The StarScan Plate Measuring Machine: Overview and Calibrations  

Microsoft Academic Search

The StarScan machine at the U.S. Naval Observatory (USNO) completed measuring photographic astrograph plates to allow determination of proper motions for the USNO CCD Astrograph Catalog (UCAC) program. All applicable 1940 AGK2 plates, about 2200 Hamburg Zone Astrograph plates, 900 Black Birch (USNO Twin Astrograph) plates, and 300 Lick Astrograph plates have been measured. StarScan comprises a CCD camera, a

N. Zacharias; L. Winter; E. R. Holdenried; J.-P. de Cuyper; T. J. Rafferty; G. L. Wycoff

2008-01-01

82

THE LICK-CARNEGIE SURVEY: FOUR NEW EXOPLANET CANDIDATES  

SciTech Connect

We present new precise HIRES radial velocity (RV) data sets of five nearby stars obtained at Keck Observatory. HD 31253, HD 218566, HD 177830, HD 99492, and HD 74156 are host stars of spectral classes F through K and show RV variations consistent with new or additional planetary companions in Keplerian motion. The orbital parameters of the candidate planets in the five planetary systems span minimum masses of M sin i = 27.43 M{sub +} to 8.28 M{sub J}, periods of 17.05-4696.95 days and eccentricities ranging from circular to extremely eccentric (e {approx} 0.63). The fifth star, HD 74156, was known to have both a 52 day and a 2500 day planet, and was claimed to also harbor a third planet at 336 days, in apparent support of the 'Packed Planetary System' hypothesis. Our greatly expanded data set for HD 74156 provides strong confirmation of both the 52 day and 2500 day planets, but strongly contradicts the existence of a 336 day planet, and offers no significant evidence for any other planets in the system.

Meschiari, Stefano; Laughlin, Gregory; Vogt, Steven S.; Rivera, Eugenio J. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Butler, R. Paul [Department of Terrestrial Magnetism, Carnegie Institute of Washington, Washington, DC 20015 (United States); Haghighipour, Nader [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Jalowiczor, Peter

2011-02-01

83

The Salt Lick Creek layered intrusion, East Kimberley region, Western Australia  

Microsoft Academic Search

The Lower Proterozoic Salt Lick Creek intrusion, East Kimberley region, Western Australia, is a layered intrusion divisible into two well-defined zones, the Basal and Main Zones, whose combined stratigraphic thickness, as now exposed, is approximately 1000 metres. The Basal Zone, 360 metres thick, contains three members, two of which (Members 1 and 3) are dominated by olivine, plagioclase cumulates (including

J. F. G. Wilkinson; M. B. Duggan; H. K. Herbert; G. I. Z. Kalocsai

1975-01-01

84

Paleontologic investigations at Big Bone Lick State Park, Kentucky: A preliminary report  

USGS Publications Warehouse

The Big Bone Lick area in Kentucky, the first widely known collecting locality for vertebrate fossils in North America, is being investigated for further faunal and geologic evidence. Mammal bones, ranging in age from Wisconsin (Tazewell?) to Recent, were recovered in 1962 from four different faunal zones in two terrace fills.

Schultz, C. B.; Tanner, L. G.; Whitmore, Jr. , F. C.; Ray, L. L.; Crawford, E. C.

1963-01-01

85

Pesticide Poisoning of Pond Lick Lake, Ohio Investigation and Resolution, June 2-July 5, 1971.  

National Technical Information Service (NTIS)

This report prepared by the contractor describes the efforts of the United States Environmental Protection Agency in rendering assistance to the State of Ohio in order to combat a potentially dangerous spill of a pesticide mixture in the Pond Lick Reservo...

1971-01-01

86

Conceptual design for a user-friendly adaptive optics system at Lick Observatory.  

National Technical Information Service (NTIS)

In this paper, we present a conceptual design for a general-purpose adaptive optics system, usable with all Cassegrain facility instruments on the 3 meter Shane telescope at the University of California's Lick Observatory located on Mt. Hamilton near San ...

H. D. Bissinger S. Olivier C. Max

1996-01-01

87

Dilute bird nectars: viscosity constrains food intake by licking in a sunbird.  

PubMed

Floral nectars of bird-pollinated plants are relatively dilute. One hypothesis proposed to explain this concerns the difficulty for birds of drinking nectar of high viscosity. We examined the effects of viscosity, separately from those of sugar concentration, on feeding by captive whitebellied sunbirds (Cinnyris talatala). Viscosities of artificial nectar (sucrose solutions ranging in concentration from 0.25 to 1.5 mol/l) were altered with Tylose, an inert polysaccharide. Food consumption was measured over 3 h, and lick frequency and duration were recorded using photodetection devices on feeding apertures too small for the bill but large enough for the extended tongue. Volumetric intake rates (ml/s) were inversely proportional to nectar viscosity, and were similar over the range of sucrose concentrations when viscosity was held constant. Sucrose intake rates (mg/s) remained the same on pure sucrose solutions, but they decreased with increasing viscosity at a constant sucrose concentration. Lick frequencies and tongue loads were reduced at high viscosities, and lick duration increased, which confirms that sunbirds take longer to ingest viscous solutions. Licking behavior was remarkably similar in birds feeding on different sucrose concentrations if viscosity was held constant. Nectar ingestion rate is determined by viscosity; however, total food intake is mainly modulated by sugar concentration. Similar effects of food viscosity have been observed in insects that suck nectar. PMID:20686174

Köhler, Angela; Leseigneur, Carolina D C; Verburgt, Luke; Nicolson, Susan W

2010-08-04

88

The Eclipse Expeditions of the Lick Observatory and the Beginnings of Astrophysics in the United States  

NASA Astrophysics Data System (ADS)

During the years 1898 to 1932, Lick Observatory organized a remarkable series of 17 solar eclipse expeditions, all the more remarkable because Lick astronomers evidenced no enduring interest in solar physics. The science of these expeditions involved three issues of major significance during the development of astrophysics during the first three decades of the twentieth century: (1) testing of General Relativity; (2) non-LTE in extended atmospheres and gaseous nebulae; (3) role of magnetic fields in the sun. The expeditions made major contributions to the first two topics. Even though W.W. Campbell, the director of Lick, had extensive contact with George Ellery Hale, who had measured the magnetic fields of sunspots at Mt. Wilson, Lick astronomers missed the clues concerning the importance of magnetic fields in the corona. Campbell's measurement of the deflection of starlight at the eclipse of 1922 was his major achievement of the many eclipse expeditions. He had approached that test of General Relativity with considerable distrust of Einstein's theory and considered Eddington's 1919 results to be suspect. It is to Campbell's great credit that the results published jointly with Trumpler confirmed the predictions of Einstein with higher precision than Eddington had achieved. Donald Menzel joined the staff of Lick Observatory in 1926 as their first astrophysicist. Osterbrock describes him as a ``stranger in a strange land.'' He was given the analysis of the eclipse flash spectra. This work, published in 1931, represents the beginning of the astrophysical study of chromospheres and laid the foundation for the quantitative analysis of extended atmospheres and gaseous nebula.

Malville, J. McKim; Pearson, John

2012-09-01

89

Laser guide star measurements at Lawrence Livermore National Laboratory  

SciTech Connect

Recent studies from the Laser Guide Star Project at Lawrence Livermore National Laboratory are presented. Photometry of the return signal has shown that the photon return is approximately 10 photons/cm{sup 2}ms at the pupil of the receiving telescope in agreement with a detailed model of the sodium interaction. Wavefronts of the laser guide star have also been measured with a Shack-Hartmann technique and power spectra have been shown to agree with those of nearby natural stars. Plans for closed loop demonstrations using the laser guide star at LLNL and nearby Lick Observatory are discussed.

Friedman, H.; Avicola, K.; Bissinger, H.; Brase, J.; Duff, J.; Gavel, D.; Horton, J.; Max, C.; Olivier, S.; Rapp, D.; Salmon, T.; Smauley, D.; Waltjen, K.

1993-02-01

90

Laser guide star measurements at Lawrence Livermore National Laboratory  

NASA Astrophysics Data System (ADS)

Recent studies from the Laser Guide Star Project at Lawrence Livermore National Laboratory are presented. Photometry of the return signal has shown that the photon return is approximately 10 photons/sq cm/ms at the pupil of the receiving telescope in agreement with a detailed model of the sodium interaction. Wavefronts of the laser guide star have also been measured with a Shack-Hartmann technique and power spectra have been shown to agree with those of nearby natural stars. Plans for closed loop demonstrations using the laser guide star at LLNL and nearby Lick Observatory are discussed.

Friedman, H.; Avicola, K.; Bissinger, H.; Brase, J.; Duff, J.; Gavel, D.; Horton, J.; Max, C.; Olivier, S.; Rapp, D.

1993-02-01

91

Synthesis of Lick Spectral Indices With Overshooting and No-Overshooting Model Atmospheres  

NASA Astrophysics Data System (ADS)

Lick indices have been widely used for interpretation of stellar content in the Local Group of galaxies. The behavior of the empirical spectral indices with basic atmospheric parameters, which is used as an input for modeling stellar populations, hampers the study of stellar populations in elliptical galaxies due to its limitation parameter space. We have been investigating the potential of theoretical spectral indices based on atmospheric models in order to complement with the empirical indices. In our earlier works we have (Gulati et al., 1993, ApJ, 413, 166; Chavez, et al., 1996, ApJ 471, 726) looked into two generation of the Kurucz's model atmospheres for consistency with empirical indices. New generation of Kurucz's models, which take into account the convection with mixing length theory with and without approximate overshooting, and model colors based on the latter criterion seem to reproduce more observations. In this paper we investigate the role of convection on the Lick indices and present preliminary results.

Gulati, R. K.; Chavez, M.

1999-01-01

92

Licking behaviour and environmental contamination arising from pour-on ivermectin for cattle  

Microsoft Academic Search

Pour-on formulations of endectocides are extensively used to treat and control systemic parasitic diseases in cattle, worldwide. The purpose of the present study was to investigate the influence of the natural licking behaviour of cattle on the plasma and faecal disposition of topically administered ivermectin. Twelve Holstein cattle were given one single intravenous (i.v.) (200 ?g\\/kg) and topical (500 ?g\\/kg)

Ce Line M. Laffont; Michel Alvinerie; Alain Bousquet-Mélou; Pierre-Louis Toutain

2001-01-01

93

Initial Licking Responses of Mice to Sweeteners: Effects of Tas1r3 Polymorphisms  

Microsoft Academic Search

Recent studies have established that the T1R3 receptor plays a central role in the taste-mediated ingestive response to sweeteners by mice. First, transgenic mice lacking the gene for T1R3, Tas1r3, show dramatically reduced lick responsiveness to most sweeteners. Second, strains with the taster allele of Tas1r3 (T strains) are more sensitive to low sweetener concentrations than strains with the nontaster

John I. Glendinning; Susan Chyou; Ivy Lin; Maika Onishi; Puja Patel; Kun Hao Zheng

2005-01-01

94

Progress with Adaptive Optics Testbeds at the UCO\\/Lick Observatory Laboratory for Adaptive Optics  

Microsoft Academic Search

We report on experimental results with adaptive optics testbeds at the UCO\\/Lick Observatory. One testbed is dedicated to high contrast AO imaging and is a prototype for a ground-based extrasolar planet imager. The second testbed is dedicated to developing concepts and architectures for multi-laser guidestar tomography in wide-field AO applications. Concurrent with the testbed experiments we are evaluating the new

Donald Gavel

2007-01-01

95

Temporal and Qualitative Dynamics of Conditioned Taste Aversion Processing: Combined Generalization Testing and Licking Microstructure Analysis  

Microsoft Academic Search

The pattern of licking microstructure during various phases of a conditioned taste aversion (CTA) was evaluated. In Experiment 1, rats ingested lithium chloride (LiCl) for 3 trials and were then offered sodium chloride (NaCl) or sucrose on 3 trials. A CTA to LiCl developed and generalized to NaCl but not to sucrose. CTA intake suppression was characterized by reductions in

John-Paul Baird; Steven James St. John; Eric Anh-Nhat Nguyen

2005-01-01

96

Online correction of licking-induced brain motion during two-photon imaging with a tunable lens.  

PubMed

Abstract? Two-photon calcium imaging in awake, head-fixed animals enables the measurement of neuronal activity during behaviour. Often, licking for the retrieval of water reward is used as a measurable report of the animal's decision during reward-driven behaviour. However, licking behaviour can induce severe motion artifacts that interfere with two-photon imaging of cellular activity. Here, we describe a simple method for the online correction of licking-induced focus shifts for two-photon calcium imaging of neocortical neurons in the head-fixed mouse. We found that licking causes a stereotyped drop of neocortical tissue, shifting neurons up to 20 ?m out of focus. Based on the measurement of licking with a piezo film sensor, we developed a feedback model, which provides a corrective signal for fast optical focus adjustments with an electrically tunable lens. Using online correction with this feedback model, we demonstrate a reduction of licking-related focus changes below 3 ?m, minimizing motion artifact contamination of cellular calcium signals. Focus correction with a tunable lens is a simple and effective method to improve the ability to monitor neuronal activity during reward-based behaviour. PMID:23940380

Chen, Jerry L; Pfäffli, Oliver A; Voigt, Fabian F; Margolis, David J; Helmchen, Fritjof

2013-08-12

97

A high-resolution spectral atlas of carbon stars  

Microsoft Academic Search

We present a spectral atlas of six bright carbon stars (U Hya, TX Psc, RZ Peg, V Oph, Y CVn, and UV Cam) observed with the Hamilton Echelle Spectrograph at coude using the 3 m telescope at Lick Observatory. These data are of high resolution (0.13 A at 6100 A) and high signal-to-noise. The spectral range spans from 5080 to

Cecilia Barnbaum

1994-01-01

98

Early Photographs of the Distant Sierra Nevada Mountains Taken from Lick Observatory  

NASA Astrophysics Data System (ADS)

During World War I, a group of American chemists, physicists and astronomers developed processes for greatly increasing the infrared sensitivity of photographic emulsions, for long-distance reconnaissance from airplanes or the ground. After the war Lick Observatory astronomers, beginning with C.D. Shane and Mary Lea Heger, used long-focal-length astronomical cameras and these hypersensitization methods to photograph the distant Sierra Nevada range, including Yosemite Valley and Half Dome, nearly one hundred miles away across the Central Valley of California. These pictures, widely exhibited and admired, strengthened links between astronomers, the Eastman Kodak Company and the public.

Osterbrock, Donald E.

2006-12-01

99

Fiber scrambling for precise radial velocities at Lick and Keck Observatories  

NASA Astrophysics Data System (ADS)

The detection of Earth analogs with radial velocity requires extreme Doppler precision and long term stability. Variations in the illumination of the slit and of the spectrograph optics occur on time scales of seconds and minutes, primarily because of guiding, seeing and focusing. These variations yield differences in the instrumental profile (IP). In order to stabilize the IP, we designed a fiber feed for the Hamilton spectrograph at Lick and for HIRES at Keck. Here, we report all results obtained with these fiber scramblers. We also present the design of a new double scrambler/pupil slicer for HIRES at Keck.

Spronck, J. F. P.; Fischer, D. A.; Kaplan, Z. A.; Schwab, C.

2012-09-01

100

A radial velocity spectrometer for the Automated Planet Finder Telescope at Lick Observatory  

NASA Astrophysics Data System (ADS)

The Ken and Gloria Levy Spectrometer is being constructed at the Instrument Development Laboratory (Technical Facilities) of UCO/ Lick Observatory for use on the 2.4 meter Automated Planet Finder Telescope at Mt. Hamilton. The mechanical design of the instrument has been optimized for precision Doppler measurements. A key component of the design is the space-frame structure that contains passive thermal compensation. Determinate hexapod structures are used to mount the collimator, prism, and echelle grating. In this paper we describe the instrument mechanical design and some features that will help it detect rocky planets in the habitable zone.

Radovan, Matthew V.; Cabak, Gerald F.; Laiterman, Lee H.; Lockwood, Christopher T.; Vogt, Steven S.

2010-07-01

101

A library of Lick Observatory Image Dissector Scanner indices for binary stellar populations  

NASA Astrophysics Data System (ADS)

Using evolutionary population synthesis, we present 13 refined absorption-line indices defined by the Lick Observatory Image Dissector Scanner (Lick/IDS) system for an extensive set of instantaneous-burst binary stellar populations (BSPs) at high resolution (~0.3 Å), and 38 indices at intermediate resolution (3 Å). The ages of the populations are at an interval of 1Gyr in the range 1-15Gyr, and the metallicities are in the range 0.004-0.03. These indices are obtained by two methods: (i) using the empirical fitting functions (FFs method); (ii) measured directly from the synthetic spectra (DC method). Together with our previous paper, a data base of Lick/IDS spectral absorption-line indices for BSPs at high and intermediate resolutions is provided. This set of indices includes 21 indices of Worthey et al., four Balmer indices defined by Worthey & Ottaviani, and 13 indices with the new passband definitions of Trager et al. The full set of synthetic indices and the integrated pseudo-continuum are listed in the Appendices, which are only available online at http://www.blackwell-synergy.com/ or from our website (http://www.ast9.com/), or on request from the first author. Moreover, the full set of the integrated spectral energy distributions can be obtained from our website. We compare the synthetic Lick/IDS indices obtained by the FFs method and those by the DC method for BSPs with various metallicities, and find that the discrepancies are significant: Ca4455 (index 6), Fe4668 (8), Mgb (13), Fe5709 (17), NaD (19), TiO1 (20) and TiO2 (21, except for Z = 0.02) in the W94 system, Ca4455T (6T), C24668T (8T), NaDT (19T), TiOT1 (20T) and TiOT2 (21T, except for Z = 0.02) in the T98 system obtained by the DC method are less (bluer) than the corresponding ones obtained by the FFs method for all metallicities. Ca4227 (index 3), Fe5782 (18), Ca4227T (3T) and Fe5782T (18T) are greater at Z = 0.03 and become bluer at Z = 0.004; the Fe5709T (17T) index is less at Z = 0.03 and becomes redder at Z = 0.004 than the corresponding ones obtained by the FFs method.

Zhang, Fenghui; Li, Lifang

2006-08-01

102

Image improvement from a sodium-layer laser guide star adaptive optics system  

SciTech Connect

A sodium-layer laser guide star beacon with high-order adaptive optics at Lick Observatory produced a factor of 2.4 intensity increase and a factor of 2 decrease in full width at half maximum for an astronomical point source, compared with image motion compensation alone. Image full widths at half maximum were identical for laser and natural guide stars (0.3 arc seconds). The Strehl ratio with the laser guide star was 65% of that with a natural guide star. This technique should allow ground-based telescopes to attain the diffraction limit, by correcting for atmospheric distortions.

Max, C. E., LLNL

1997-06-01

103

Population Synthesis in the Blue. IV. Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations  

NASA Astrophysics Data System (ADS)

We present a new set of model predictions for 16 Lick absorption line indices from H? through Fe5335 and UBV colors for single stellar populations with ages ranging between 1 and 15 Gyr, [Fe/H] ranging from -1.3 to +0.3, and variable abundance ratios. The models are based on accurate stellar parameters for the Jones library stars and a new set of fitting functions describing the behavior of line indices as a function of effective temperature, surface gravity, and iron abundance. The abundances of several key elements in the library stars have been obtained from the literature in order to characterize the abundance pattern of the stellar library, thus allowing us to produce model predictions for any set of abundance ratios desired. We develop a method to estimate mean ages and abundances of iron, carbon, nitrogen, magnesium, and calcium that explores the sensitivity of the various indices modeled to those parameters. The models are compared to high-S/N data for Galactic clusters spanning the range of ages, metallicities, and abundance patterns of interest. Essentially all line indices are matched when the known cluster parameters are adopted as input. Comparing the models to high-quality data for galaxies in the nearby universe, we reproduce previous results regarding the enhancement of light elements and the spread in the mean luminosity-weighted ages of early-type galaxies. When the results from the analysis of blue and red indices are contrasted, we find good consistency in the [Fe/H] that is inferred from different Fe indices. Applying our method to estimate mean ages and abundances from stacked SDSS spectra of early-type galaxies brighter than L*, we find mean luminosity-weighed ages of the order of ~8 Gyr and iron abundances slightly below solar. Abundance ratios, [X/Fe], tend to be higher than solar and are positively correlated with galaxy luminosity. Of all elements, nitrogen is the more strongly correlated with galaxy luminosity, which seems to indicate secondary nitrogen enrichment. If that interpretation is correct, this result may impose a lower limit of 50-200 Myr to the timescale of star formation in early-type galaxies. Unlike clusters, galaxies show a systematic effect whereby higher order, bluer, Balmer lines yield younger ages than H?. This age discrepancy is stronger for lower luminosity galaxies. We examine four possible scenarios to explain this trend. Contamination of the bluer indices by a metal-poor stellar population with a blue horizontal branch cannot account for the data. Blue stragglers and abundance-ratio effects cannot be ruled out, as they can potentially satisfy the data, even though this can only be achieved by resorting to extreme conditions, such as extremely high [O/Fe] or specific blue-straggler frequencies. The most likely explanation is the presence of small amounts of a young/intermediate-age stellar population component. We simulate this effect by producing two-component models and show that they provide a reasonably good match to the data when the mass fraction of the young component is typically a few percent. If confirmed, this result implies star formation has been extended in early-type galaxies, and more so in less massive galaxies, which seems to lend support to the ``downsizing'' scenario. Moreover, it implies that stellar population synthesis models are capable of constraining not only the mean ages of stellar populations in galaxies, but also their age spread.

Schiavon, Ricardo P.

2007-07-01

104

The Lick-index Calibration of the Gemini Multi-Object Spectrographs  

NASA Astrophysics Data System (ADS)

We present the calibration of the spectroscopic Lick/IDS standard line-index system for measurements obtained with the Gemini Multi-Object Spectrographs known as GMOS-North and GMOS-South. We provide linear correction functions for each of the 25 standard Lick line indices for the B600 grism and two instrumental setups, one with 0.''5 slit width and 1 × 1 CCD pixel binning (corresponding to ~2.5 Å spectral resolution) and the other with 0.''75 slit width and 2 × 2 binning (~4 Å). We find small and well-defined correction terms for the set of Balmer indices H?, H? A , and H? A along with the metallicity sensitive indices Fe5015, Fe5270, Fe5335, Fe5406, Mg2, and Mgb that are widely used for stellar population diagnostics of distant stellar systems. We find other indices that sample molecular absorption bands, such as TiO1 and TiO2, with very wide wavelength coverage or indices that sample very weak molecular and atomic absorption features, such as Mg1, as well as indices with particularly narrow passband definitions, such as Fe4384, Ca4455, Fe4531, Ca4227, and Fe5782, which are less robustly calibrated. These indices should be used with caution.

Puzia, Thomas H.; Miller, Bryan W.; Trancho, Gelys; Basarab, Brett; Mirocha, Jordan T.; Butler, Karen

2013-06-01

105

Effects of mGlu1 receptor blockade on anxiety-related behaviour in the rat lick suppression test  

Microsoft Academic Search

Rationale: Group I metabotropic glutamate re- ceptor antagonists, which block both the mGlu1 and mGlu5 receptors, have been shown to have anxiolytic effects in the lick suppression test in rats. Objective: The anxiolytic potential of the selective mGlu1 antagonist 3,4-dihydro- 2H-pyrano(2,3)?-quinolin-7-yl)(cis-4-methoxycyclohexyl) methanone (JNJ16259685) was investigated and compared with the mGlu5 antagonist MPEP. Methods: Anxiety-re- lated behaviour was assessed in lick

Thomas Steckler; Hilde Lavreysen; Ana M. Oliveira; Nancy Aerts; Hansfried Van Craenendonck; Jos Prickaerts; Anton Megens; Anne S. J. Lesage

2005-01-01

106

The StarScan plate measuring machine: overview and calibrations  

Microsoft Academic Search

The StarScan machine at the U.S. Naval Observatory (USNO) completed measuring\\u000aphotographic astrograph plates to allow determination of proper motions for the\\u000aUSNO CCD Astrograph Catalog (UCAC) program. All applicable 1940 AGK2 plates,\\u000aabout 2200 Hamburg Zone Astrograph plates, 900 Black Birch (USNO Twin\\u000aAstrograph) plates, and 300 Lick Astrograph plates have been measured. StarScan\\u000acomprises of a CCD camera,

Norbert Zacharias; Lars Winter; Ellis Holdenried; Jean-Pierre de Cuyper; Ted Rafferty; Gary Wycoff

2008-01-01

107

Acute effects of corticosterone on LiCl-induced rapid gustatory conditioning in rats: a microstructural analysis of licking patterns.  

PubMed

Acute administration of corticosterone (Cort) has been shown to potentiate a variety of learning processes. Here, the effects of Cort on rapid gustatory conditioning were examined using a lick monitoring system. Over a 3-day period, animals were given intraperitoneal (ip) injections of either a low dose of lithium chloride (LiCl; 0.75 mEq, ip) toxin or saline control (NaCl; 0.9%, ip) and then received an injection of Cort (5 mg/kg, ip) or cyclodextrin vehicle. In order to investigate the effect of acute increases in systemic Cort on gustatory conditioning, patterns of licking behavior were recorded while animals were exposed to a novel sucrose (0.3 M) tastant. Increased post-injection serum Cort levels were verified by radioimmunoassay analysis of trunk blood samples. Analysis of the licking patterns revealed evidence of rapid gustatory conditioning. Significantly reduced sucrose intake volumes and fewer total licks during the test sessions on Conditioning days were found in all groups that had received LiCl injections. Evidence of a Cort-potentiated conditioning effect was also found. Animals that had received Cort in addition to LiCl exhibited significantly shorter meal durations than did animals that had been administered LiCl alone and Cort significantly influenced the effects of LiCl on cluster number. These findings indicate that Cort facilitates conditioning, possibly by modulation of LiCl-induced visceral afferent and/or central feedback mechanisms. PMID:12385799

Kent, William D T; Cross-Mellor, Shelley K; Kavaliers, Martin; Ossenkopp, Klaus Peter

2002-10-17

108

Greater Superficial Petrosal Nerve Transection in Rats does not Change Unconditioned Licking Responses to Putatively Sweet Taste Stimuli  

Microsoft Academic Search

The greater superficial petrosal nerve (GSP), innervating taste buds in the palate, is known to be exceptionally responsive to sucrose, especially compared with the responsiveness of the chorda tympani nerve (CT). However, whereas transection of the CT (CTX) alone has little or no effect on unconditioned licking responses to many ''sweet'' stimuli, the impact of GSP transection (GSPX) alone is

Enshe Jiang; Ginger Blonde; Mircea Garcea; Alan C. Spector

2008-01-01

109

Sodium Laser Guide Star Adaptive Optics Imaging Polarimetry of Herbig Ae/Be Stars  

SciTech Connect

The future of high-resolution ground-based optical and infrared astronomy requires the successful implementation of laser guide star adaptive optics systems. We present the first science results from the Lick Observatory sodium beacon laser guide star system. By coupling this system to a near-infrared (J;H;Ks bands) dual-channel imaging polarimeter, we achieve very high sensitivity to light scattered in the circumstellar enviroment of Herbig Ae/Be stars on scales of 100-300 AU. Observations of LkH{alpha} 198 reveal a highly polarized, biconical nebula 10 arcseconds in diameter (6000 AU) . We also observe a polarized jet-like feature associated with the deeply embedded source LkH{alpha} 198-IR. The star LkH{alpha} 233 presents a narrow, unpolarized dark lane dividing its characteristic butterfly-shaped polarized reflection nebulosity. This linear structure is oriented perpendicular to an optical jet and bipolar cavity and is consistent with the presence of an optically thick circumstellar disk blocking our direct view of the star. These data suggest that the evolutionary picture developed for the lower-mass T Tauri stars is also relevant to the Herbig Ae/Be stars and demonstrate the ability of laser guide star adaptive optics systems to obtain scientific results competitive with natural guide star adaptive optics or space-based telescopes.

Perrin, M D; Graham, J R; Lloyd, J P; Kalas, P; Gates, E L; Gavel, D T; Pennington, D M; Max, C E

2004-01-08

110

Retired A Stars and Their Companions. III. Comparing the Mass-Period Distributions of Planets Around A-Type Stars and Sun-Like Stars  

NASA Astrophysics Data System (ADS)

We present an analysis of ~5 years of Lick Observatory radial velocity measurements targeting a uniform sample of 31 intermediate-mass (IM) subgiants (1.5 lsim M */M sunlsim 2.0) with the goal of measuring the occurrence rate of Jovian planets around (evolved) A-type stars and comparing the distributions of their orbital and physical characteristics to those of planets around Sun-like stars. We provide updated orbital solutions incorporating new radial velocity measurements for five known planet-hosting stars in our sample; uncertainties in the fitted parameters are assessed using a Markov-Chain Monte Carlo method. The frequency of Jovian planets interior to 3 AU is 26+9 -8%, which is significantly higher than the 5%-10% frequency observed around solar-mass stars. The median detection threshold for our sample includes minimum masses down to {0.2, 0.3, 0.5, 0.6, 1.3} M Jup within {0.1, 0.3, 0.6, 1.0, 3.0} AU. To compare the properties of planets around IM stars to those around solar-mass stars we synthesize a population of planets based on the parametric relationship dN vprop M ? P ? dlnMdlnP, the observed planet frequency, and the detection limits we derived. We find that the values of ? and ? for planets around solar-type stars from Cumming et al. fail to reproduce the observed properties of planets in our sample at the 4? level, even when accounting for the different planet occurrence rates. Thus, the properties of planets around A stars are markedly different than those around Sun-like stars, suggesting that only a small (~50%) increase in stellar mass has a large influence on the formation and orbital evolution of planets. Based on observations obtained at the Lick Observatory, which is operated by the University of California.

Bowler, Brendan P.; Johnson, John Asher; Marcy, Geoffrey W.; Henry, Gregory W.; Peek, Kathryn M. G.; Fischer, Debra A.; Clubb, Kelsey I.; Liu, Michael C.; Reffert, Sabine; Schwab, Christian; Lowe, Thomas B.

2010-01-01

111

Scanner Abundance in late-type evolved stars (Spinrad+ 1969)  

NASA Astrophysics Data System (ADS)

Abundance parameters have been derived from scanner observations of 229 stars. Observations were made with the Wampler photoelectric spectrum scanner (Wampler, 1966) on Lick Observatory's Crossley and 120inch telescopes. Data reductions were performed at UC Berkeley on the IBM 7094 computer using programs by L.V. Kuhi and B.J. Taylor. The method of reduction and the photometric standard system are described by Spinrad and Taylor (1969AJ.....72..320S). The file "color.dat" (tables 5 and 6 in the publication) gives colors between 3880 and 7400{AA} for program stars and survey stars, normalized so that I(5360)=1000. The file "block.dat" gives the blocking fractions for program stars. (4 data files).

Spinrad, H.; Taylor, B. J.

2002-04-01

112

Effects of movement and eating on chemosensory tongue-flicking and on labial-licking in the leopard gecko ( Eublepharis macularius )  

Microsoft Academic Search

Summary Two forms of lingual protrusion, tongueflicking and labial-licking, were differentially affected by combinations of movement and eating conditions in a eublepharid gecko (Eublepharis macularius). Tongue-flicking, in which the tongue contacts substrates beyond the lizard's body, occurred at increased rates during locomotion and during locomotion was significantly more frequent after eating than in a baseline condition. Labial-licking, in which a

William E. Cooper; C. S. DePerno; Laura J. Steele

1996-01-01

113

Retired A Stars and Their Companions: Exoplanets Orbiting Three Intermediate-Mass Subgiants  

Microsoft Academic Search

We report precision Doppler measurements of three intermediate-mass subgiants obtained at Lick and Keck Observatories. All three stars show variability in their radial velocities consistent with planet-mass companions in Keplerian orbits. We find a planet with a minimum mass MPsini=2.5 MJ in a 351.5 day orbit around HD 192699, a planet with a minimum mass of 2.0 MJ in a

John Asher Johnson; Debra A. Fischer; Geoffrey W. Marcy; Jason T. Wright; Peter Driscoll; R. Paul Butler; Saskia Hekker; Sabine Reffert; Steven S. Vogt

2007-01-01

114

Triaxial ellipsoid dimensions and rotational poles of seven asteroids from Lick Observatory adaptive optics images, and of Ceres  

NASA Astrophysics Data System (ADS)

Seven main belt asteroids, 2 Pallas, 3 Juno, 4 Vesta, 16 Psyche, 87 Sylvia, 324 Bamberga, and 707 Interamnia, were imaged with the adaptive optics system on the 3 m Shane telescope at Lick Observatory in the near infrared, and their triaxial ellipsoid dimensions and rotational poles have been determined with parametric blind deconvolution. In addition, the dimensions and pole for 1 Ceres are derived from resolved images at multiple epochs, even though it is an oblate spheroid.

Drummond, Jack; Christou, Julian

2008-10-01

115

The Selective Serotonin Reuptake Inhibitor Paroxetine Does Not Alter Consummatory Concentration-Dependent Licking of Prototypical Taste Stimuli by Rats  

PubMed Central

Serotonin and the 5HT1A receptor are expressed in a subset of taste receptor cells, and the 5HT3 receptor is expressed on afferent fibers innervating taste buds. Exogenous administration of the selective serotonin reuptake inhibitor, paroxetine, has been shown to increase taste sensitivity to stimuli described by humans as sweet and bitter. Serotonergic agonists also decrease food and fluid intake, and it is possible that modulations of serotonin may alter taste-based hedonic responsiveness; alternatively, or in combination, serotonin may interact with physiological state to impact ingestive behavior. In this study, the unconditioned licking of prototypical taste stimuli by rats in brief-access taste tests was assessed following paroxetine administration (0.3–10 mg/kg intraperitoneal). We also measured sucrose licking by rats in different deprivation states after paroxetine (5 mg/kg). In neither experiment did we find any evidence of an effect of paroxetine on licking relative to water to any of the taste stimuli in the brief-access test at doses that decreased food intake. However, in some conditions, paroxetine decreased trials initiated to tastants. Therefore, a systemic increase in serotonin via paroxetine administration can decrease appetitive behavior in brief-access tests but is insufficient to alter taste-guided consummatory behavior.

Spector, Alan C.

2011-01-01

116

THE LICK AGN MONITORING PROJECT: ALTERNATE ROUTES TO A BROAD-LINE REGION RADIUS  

SciTech Connect

It is now possible to estimate black hole (BH) masses across cosmic time, using broad emission lines in active galaxies. This technique informs our views of how galaxies and their central BHs coevolve. Unfortunately, there are many outstanding uncertainties associated with these 'virial' mass estimates. One of these comes from using the accretion luminosity to infer a size for the broad-line region (BLR). Incorporating the new sample of low-luminosity active galaxies from our recent monitoring campaign at Lick Observatory, we recalibrate the radius-luminosity relation with tracers of the accretion luminosity other than the optical continuum. We find that the radius of the BLR scales as the square root of the X-ray and H{beta} luminosities, in agreement with recent optical studies. On the other hand, the scaling appears to be marginally steeper with narrow-line luminosities. This is consistent with a previously observed decrease in the ratio of narrow-line to X-ray luminosity with increasing total luminosity. The radius of the BLR correlates most tightly with H{beta} luminosity, while the X-ray and narrow-line relations both have comparable scatter of a factor of 2. These correlations provide useful alternative virial BH masses in objects with no detectable optical/UV continuum emission, such as high-redshift galaxies with broad emission lines, radio-loud objects, or local active galaxies with galaxy-dominated continua.

Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Hood, Carol E.; Barth, Aaron J.; Bentz, Misty C.; Walsh, Jonelle L. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697-4575 (United States); Bennert, Vardha N.; Treu, Tommaso [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90024 (United States); Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul, Korea, 151-742 (Korea, Republic of)

2010-11-01

117

The Lick AGN Monitoring Project 2011: Fe II Reverberation from the Outer Broad-line Region  

NASA Astrophysics Data System (ADS)

The prominent broad Fe II emission blends in the spectra of active galactic nuclei have been shown to vary in response to continuum variations, but past attempts to measure the reverberation lag time of the optical Fe II lines have met with only limited success. Here we report the detection of Fe II reverberation in two Seyfert 1 galaxies, NGC 4593 and Mrk 1511, based on data from a program carried out at Lick Observatory in Spring 2011. Light curves for emission lines including H? and Fe II were measured by applying a fitting routine to decompose the spectra into several continuum and emission-line components, and we use cross-correlation techniques to determine the reverberation lags of the emission lines relative to V-band light curves. In both cases, the measured lag (?cen) of Fe II is longer than that of H?, although the inferred lags are somewhat sensitive to the choice of Fe II template used in the fit. For spectral decompositions done using the Fe II template of Véron-Cetty et al., we find ?cen(Fe II)/?cen(H?) = 1.9 ± 0.6 in NGC 4593 and 1.5 ± 0.3 in Mrk 1511. The detection of highly correlated variations between Fe II and continuum emission demonstrates that the Fe II emission in these galaxies originates in photoionized gas, located predominantly in the outer portion of the broad-line region.

Barth, Aaron J.; Pancoast, Anna; Bennert, Vardha N.; Brewer, Brendon J.; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor L.; Greene, Jenny E.; Li, Weidong; Malkan, Matthew A.; Sand, David J.; Stern, Daniel; Treu, Tommaso; Woo, Jong-Hak; Assef, Roberto J.; Bae, Hyun-Jin; Buehler, Tabitha; Cenko, S. Bradley; Clubb, Kelsey I.; Cooper, Michael C.; Diamond-Stanic, Aleksandar M.; Hönig, Sebastian F.; Joner, Michael D.; Laney, C. David; Lazarova, Mariana S.; Nierenberg, A. M.; Silverman, Jeffrey M.; Tollerud, Erik J.; Walsh, Jonelle L.

2013-06-01

118

THE LICK AGN MONITORING PROJECT 2011: REVERBERATION MAPPING OF MARKARIAN 50  

SciTech Connect

The Lick AGN Monitoring Project 2011 observing campaign was carried out over the course of 11 weeks in spring 2011. Here we present the first results from this program, a measurement of the broad-line reverberation lag in the Seyfert 1 galaxy Mrk 50. Combining our data with supplemental observations obtained prior to the start of the main observing campaign, our data set covers a total duration of 4.5 months. During this time, Mrk 50 was highly variable, exhibiting a maximum variability amplitude of a factor of {approx}4 in the U-band continuum and a factor of {approx}2 in the H{beta} line. Using standard cross-correlation techniques, we find that H{beta} and H{gamma} lag the V-band continuum by {tau}{sub cen} = 10.64{sup +0.82}{sub -0.93} and 8.43{sup +1.30}{sub -1.28} days, respectively, while the lag of He II {lambda}4686 is unresolved. The H{beta} line exhibits a symmetric velocity-resolved reverberation signature with shorter lags in the high-velocity wings than in the line core, consistent with an origin in a broad-line region (BLR) dominated by orbital motion rather than infall or outflow. Assuming a virial normalization factor of f = 5.25, the virial estimate of the black hole mass is (3.2 {+-} 0.5) Multiplication-Sign 10{sup 7} M{sub Sun }. These observations demonstrate that Mrk 50 is among the most promising nearby active galaxies for detailed investigations of BLR structure and dynamics.

Barth, Aaron J.; Thorman, Shawn J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697-4575 (United States); Pancoast, Anna; Bennert, Vardha N.; Sand, David J.; Treu, Tommaso; Brewer, Brendon J. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Li, Weidong; Filippenko, Alexei V.; Cenko, S. Bradley; Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Gates, Elinor L. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Stern, Daniel; Assef, Roberto J. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Boulevard, Pasadena, CA 91109 (United States); Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Bae, Hyun-Jin [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of); Buehler, Tabitha, E-mail: barth@uci.edu [Department of Physics and Astronomy, N283 ESC, Brigham Young University, Provo, UT 84602-4360 (United States); and others

2011-12-10

119

A low-cost solution to measure mouse licking in an electrophysiological setup with a standard analog-to-digital converter.  

PubMed

Licking behavior in rodents is widely used to determine fluid consumption in various behavioral contexts and is a typical example of rhythmic movement controlled by internal pattern-generating mechanisms. The measurement of licking behavior by commercially available instruments is based on either tongue protrusion interrupting a light beam or on an electrical signal generated by the tongue touching a metal spout. We report here that licking behavior can be measured with high temporal precision by simply connecting a metal sipper tube to the input of a standard analog/digital (A/D) converter and connecting the animal to ground (via a metal cage floor). The signal produced by a single lick consists of a 100-800 mV dc voltage step, which reflects the metal-to-water junction potential and persists for the duration of the tongue-spout contact. This method does not produce any significant electrical artifacts and can be combined with electrophysiological measurements of single unit activity from neurons involved in the control of the licking behavior. PMID:16364450

Hayar, Abdallah; Bryant, Jeri L; Boughter, John D; Heck, Detlef H

2005-12-20

120

Measurement of the reaeration coefficients of the North Fork Licking River at Utica, Ohio by radioactive tracers  

USGS Publications Warehouse

Reaeration coefficients of the North Fork Licking River at Utica, Ohio were measured by the radioactive-tracer method. The tests were conducted on a 2.1-mile reach on September 23 and October 7, 1981, during low-flow conditions. Krypton-85 gas and tritium were the radioopactive tracers, which were used in conjunction with rhodamine-WT dye. The reaertion coefficients determined on September 23 were 3.09 days-1 (subreach 1-2) and 3.32 days-1 (subreach 2-3). On October 7, the values were 2.04 days -1 and 2.23 days-1 respectively.

Hren, Janet

1983-01-01

121

THE LICK AGN MONITORING PROJECT: RECALIBRATING SINGLE-EPOCH VIRIAL BLACK HOLE MASS ESTIMATES  

SciTech Connect

We investigate the calibration and uncertainties of black hole (BH) mass estimates based on the single-epoch (SE) method, using homogeneous and high-quality multi-epoch spectra obtained by the Lick Active Galactic Nucleus (AGN) Monitoring Project for nine local Seyfert 1 galaxies with BH masses <10{sup 8} M{sub Sun }. By decomposing the spectra into their AGNs and stellar components, we study the variability of the SE H{beta} line width (full width at half-maximum intensity, FWHM{sub H{beta}} or dispersion, {sigma}{sub H{beta}}) and of the AGN continuum luminosity at 5100 A (L{sub 5100}). From the distribution of the 'virial products' ({proportional_to} FWHM{sub H{beta}}{sup 2} L{sup 0.5}{sub 5100} or {sigma}{sub H{beta}}{sup 2} L{sup 0.5}{sub 5100}) measured from SE spectra, we estimate the uncertainty due to the combined variability as {approx}0.05 dex (12%). This is subdominant with respect to the total uncertainty in SE mass estimates, which is dominated by uncertainties in the size-luminosity relation and virial coefficient, and is estimated to be {approx}0.46 dex (factor of {approx}3). By comparing the H{beta} line profile of the SE, mean, and root-mean-square (rms) spectra, we find that the H{beta} line is broader in the mean (and SE) spectra than in the rms spectra by {approx}0.1 dex (25%) for our sample with FWHM{sub H{beta}} <3000 km s{sup -1}. This result is at variance with larger mass BHs where the difference is typically found to be much less than 0.1 dex. To correct for this systematic difference of the H{beta} line profile, we introduce a line-width dependent virial factor, resulting in a recalibration of SE BH mass estimators for low-mass AGNs.

Park, Daeseong; Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Treu, Tommaso; Bennert, Vardha N. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Barth, Aaron J.; Walsh, Jonelle [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697-4575 (United States); Bentz, Misty C. [Department of Physics and Astronomy, Georgia State University Atlanta, GA 30303 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, 900 University Ave., Riverside, CA 92521 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Malkan, Matthew A., E-mail: woo@astro.snu.ac.kr [Department of Physics and Astronomy, University of California, Los Angeles, CA 90024 (United States)

2012-03-01

122

Extreme Stars  

Microsoft Academic Search

Over the past 200 years, our knowledge of stars has expanded enormously. From seeing myriad dots of different brightnesses, we haved moved on to measure their distances, temperatures, sizes, chemical compositions, and even ages, finding both young and ancient stars that dwarf our Sun and are dwarfed by it. Unique in its approach, Extreme Stars describes the lives of stars

James B. Kaler

2001-01-01

123

Stars and Star Myths.  

ERIC Educational Resources Information Center

|Myths and tales from around the world about constellations and facts about stars in the constellations are presented. Most of the stories are from Greek and Roman mythology; however, a few Chinese, Japanese, Polynesian, Arabian, Jewish, and American Indian tales are also included. Following an introduction, myths are presented for the following…

Eason, Oliver

124

Precise radial velocities of giant stars. III. Spectroscopic stellar parameters  

NASA Astrophysics Data System (ADS)

Context: A radial velocity survey of about 380 G and K giant stars is ongoing at Lick observatory. For each star we have a high signal to noise ratio template spectrum, which we use to determine spectroscopic stellar parameters. Aims: The aim of this paper is to present spectroscopic stellar parameters, i.e. effective temperature, surface gravity, metallicity and rotational velocity for our sample of G and K giant stars. Methods: Effective temperatures, surface gravities and metallicities are determined from the equivalent width of iron lines, by imposing excitation and ionisation equilibrium through stellar atmosphere models. Rotational velocities are determined from the full width at half maximum (FWHM) of moderate spectral lines. A calibration between the FWHM and total broadening (rotational velocity and macro turbulence) is obtained from stars in common between our sample and the sample from Gray (1989, ApJ, 347, 1021). Macro turbulence is determined from the macro turbulence vs. spectral type relations from Gray (2005, The Observation and Analysis of Stellar Photospheres). Results: The metallicity we derive is essentially equal to the literature values, while the effective temperature and surface gravity are slightly higher by 56 K and 0.15 dex, respectively. A method comparison is performed with 72 giants in common with Luck & Heiter (2007, AJ, 133, 2464), which shows that both methods give similar results. Our rotational velocities are comparable with those obtained by Gray (1989, ApJ, 347, 1021), but somewhat higher than those of de Medeiros & Mayor (1999, A&AS, 139, 433), which is consistent with the different diagnostics used to determine them. Conclusions: We are able to determine spectroscopic stellar parameters for about 380 G and K giant stars uniformly (112 stars are being analysed spectroscopically for the first time). For stars available in the literature, we find reasonable agreement between literature values and values determined in the present work. In addition, we show that the metallicity enhancement of companion hosting stars might also be valid for giant stars, with the planet hosting giants being 0.13 ± 0.03 dex (i.e. 35 ± 10%) more metal rich than our total sample of stars. Based on data obtained at UCO/Lick Observatory, USA. Table 4 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/475/1003

Hekker, S.; Meléndez, J.

2007-12-01

125

Liquid Feed Passage Route into Stomach Compartments, Influence of Abomasal Infusions on Plasma Glucose, and Supplementation of Dry Rations with Liquid Feeds from Lick-Wheel Feeders1  

Microsoft Academic Search

Passage route into stomach compart- ments of liquid feeds containing a marker was studied by feeding a liquid supple- ment and molasses from a lick-wheel feeder and by infusing the liquid supple- ment into the reticulorumen 30 rain prior to sampling contents of the reticuloru- men and abomasum and 4 h prior to sampling blood for plasma glucose. Re- covery

L. H. Whitlow; S. P. Marshall; H. H. Van Horn; J. R. Flores

1976-01-01

126

Variable stars  

SciTech Connect

This book covers the following topics: pulsating variables; eruptive variables; eclipsing stars; supplement to the classification; the discovery of variable stars; the significance of variable stars for research on the structure of the galaxy and stellar evolution; and observational methods and organizations.

Hoffmeister, C.; Richter, G.; Wenzel, W.

1985-01-01

127

The remote-controlled spectrograph, area scanner, and spectropolarimeter for the Lick 3-m telescope  

NASA Astrophysics Data System (ADS)

A Cassegrain spectrograph used in conjunction with an image-tube, image-dissector scanner (ITS) is discussed with reference to its design features and operation. The spectrograph has a remote control feature, and its parameters, such as slit width, decker position, filter selection, focus, and grating selection, can be easily changed by computer command or a hard-wired control box. The discussion also includes the area scanner modification which allows raster scanning and limited picture taking. Finally, the design of a two-channel polarization analyzer is presented which allows simultaneous sky and sky-plus-star observations and faint-object polarimetry.

Miller, J. S.; Robinson, L. B.; Schmidt, G. D.

1980-10-01

128

The Washington Visual Double Star Catalog (Mason+ 2001-2013)  

NASA Astrophysics Data System (ADS)

The Washington Visual Double Star Catalog (WDS) is the successor to the Index Catalogue of Visual Double Stars, 1961.0 (IDS; Jeffers and van den Bos, Publ. Lick Obs. 21). Three earlier double star catalogs in XXth century, those by Burnham (BDS, 1906, "General Catalogue of Double Stars within 121 degrees of the North Pole", Carnegie Institution of Washington), Innes (SDS, 1927, "Southern Double Star Catalogue -19 to -90 degrees", Union Observatory, Johannesburg, South Africa), and Aitken (ADS, 1932 "New General Catalogue of Double Stars within 121 degrees of the North Pole", Carnegie Institution of Washington), each covered only a portion of the sky. Both the IDS and the WDS cover the entire sky, and the WDS is intended to contain all known visual double stars for which at least one differential measure has been published. The WDS is continually updated as published data become available. Prior to this, three major updates have been published (Worley and Douglass 1984, "Washington Visual Double Star Catalog, 1984.0", U.S. Naval Observatory, Washington; Worley and Douglass 1997A&AS..125..523W, Cat. I/237; Mason, Wycoff, Hartkopf, Douglass and Worley 2001AJ....122.3466M; and Mason et al. 2006.5). The Washington Double Star Catalog (WDS) has seen numerous changes since the last major release of the catalog. The application of many techniques and considerable industry over the past few years has yielded significant gains in both the number of systems and the number of measures. Is is maintained by the US Naval Observatory, and represents the world's principal database of astrometric double and multiple star information. The WDS contains positions (J2000), discoverer designations, epochs, position angles, separations, magnitudes, spectral types, proper motions, and, when available, Durchmusterung numbers and notes for the components of the systems. (3 data files).

Mason, B. D.; Wycoff, G. L.; Hartkopf, W. I.; Douglass, G. G.; Worley, C. E.

2013-10-01

129

Ground-Water Data and Flow Directions in the Vicinity of Swamp Road, Licking County, Ohio, 2006-07  

USGS Publications Warehouse

The Natural Resources Conservation Service (NRCS) is proposing to build a dry dam on the South Fork Licking River to mitigate flood impacts. Concerns have been raised regarding the effects of impounded floodwaters on ground-water conditions in the Swamp Road neighborhood. To obtain a better understanding of existing ground-water conditions, the U.S. Geological Survey, in cooperation with the NRCS, installed three monitoring wells and collected ground-water-quality samples on two occasions from these and four residential wells. In addition, transducers were placed in these seven wells to obtain hourly water-level measurements from August, 2006 to early March, 2007. Intermittent water levels also were measured in another seven residential wells in the area. Water-quality samples were collected in September 2006 and January 2007. Samples were analyzed for nutrients, inorganic elements, and fecal-indicator bacteria. In general, the ground-water quality was very hard with large iron concentrations of 1,700 ?g/L and above. Although the aquifer underlying the Swamp Road area is confined, the continuous water-level records indicate a rapid response to precipitation. Comparison of the well hydrographs with the stage hydrograph for the nearby South Fork Licking River indicates a hydraulic connection between the river and the aquifer. In the vicinity of Swamp Road, the ground-water-flow direction was southeast during the duration of the study. The ground-water-level elevations were above the planned maximum elevation for water impounded by the dam, thus the impounded floodwater should have minimal impact on ground-water conditions along Swamp Road.

Dumouchelle, Denise H.

2007-01-01

130

Massive binary stars as a probe of massive star formation  

NASA Astrophysics Data System (ADS)

Massive stars are among the largest and most influential objects we know of on a sub-galactic scale. Binary systems, composed of at least one of these stars, may be responsible for several types of phenomena, including type Ib/c supernovae, short and long gamma ray bursts, high-velocity runaway O and B-type stars, and the density of the parent star clusters. Our understanding of these stars has met with limited success, especially in the area of their formation. Current formation theories rely on the accumulated statistics of massive binary systems that are limited because of their sample size or the inhomogeneous environments from which the statistics are collected. The purpose of this work is to provide a higher-level analysis of close massive binary characteristics using the radial velocity information of 113 massive stars (B3 and earlier) and binary orbital properties for the 19 known close massive binaries in the Cygnus OB2 Association. This work provides an analysis using the largest amount of massive star and binary information ever compiled for an O-star rich cluster like Cygnus OB2, and compliments other O-star binary studies such as NGC 6231, NGC 2244, and NGC 6611. I first report the discovery of 73 new O or B-type stars and 13 new massive binaries by this survey. This work involved the use of 75 successful nights of spectroscopic observation at the Wyoming Infrared Observatory in addition to observations obtained using the Hydra multi-object spectrograph at WIYN, the HIRES echelle spectrograph at KECK, and the Hamilton spectrograph at LICK. I use these data to estimate the spectrophotometric distance to the cluster and to measure the mean systemic velocity and the one-sided velocity dispersion of the cluster. Finally, I compare these data to a series of Monte Carlo models, the results of which indicate that the binary fraction of the cluster is 57 +/- 5% and that the indices for the power law distributions, describing the log of the periods, mass-ratios, and eccentricities, are --0.2 +/- 0.3, 0.3 +/- 0.3, and --0.8 +/- 0.3 respectively (or not consistent with a simple power law distribution). The observed distributions indicate a preference for short period systems with nearly circular orbits and companions that are not likely drawn from a standard initial mass function, as would be expected from random pairing. An interesting and unexpected result is that the period distribution is inconsistent with a standard power-law slope stemming mainly from an excess of periods between 3 and 5 days and an absence of periods between 7 and 14 days. One possible explanation of this phenomenon is that the binary systems with periods from 7--14 days are migrating to periods of 3--5 days. In addition, the binary distribution here is not consistent with previous suggestions in the literature that 45% of OB binaries are members of twin systems (mass ratio near 1).

Kiminki, Daniel C.

2010-10-01

131

The StarScan Plate Measuring Machine: Overview and Calibrations  

NASA Astrophysics Data System (ADS)

The StarScan machine at the U.S. Naval Observatory (USNO) completed measuring photographic astrograph plates to allow determination of proper motions for the USNO CCD Astrograph Catalog (UCAC) program. All applicable 1940 AGK2 plates, about 2200 Hamburg Zone Astrograph plates, 900 Black Birch (USNO Twin Astrograph) plates, and 300 Lick Astrograph plates have been measured. StarScan comprises a CCD camera, a telecentric lens, an air-bearing granite table, stepper motor screws, and Heidenhain scales to operate in a step-stare mode. The repeatability of StarScan measures is about 0.2 ?m. The CCD mapping as well as the global table coordinate system has been calibrated using a special dot calibration plate and the overall accuracy of StarScan y data is derived to be 0.5 ?m. Application to real photographic plate data shows that position information of at least 0.65 ?m accuracy can be extracted from coarse-grain 103a-type emulsion astrometric plates. Transformations between "direct" and "reverse" measures of fine-grain emulsion plate measures are obtained on the 0.3 ?m level per well-exposed stellar image and coordinate, a level that is at the limit of the StarScan machine.

Zacharias, N.; Winter, L.; Holdenried, E. R.; de Cuyper, J.-P.; Rafferty, T. J.; Wycoff, G. L.

2008-05-01

132

Symbiotic Stars  

NASA Astrophysics Data System (ADS)

During the production of the Henry Draper Catalog, Wilhemina Fleming identified several M-type stars with unusually strong hydrogen emission lines. Paul Merrill obtained higher quality spectra of these `stars with combination spectra' and found intense emission from He II or [O III] and [Ne III] in addition to H I. All of these stars varied by 0.5-1 mag on a timescale of several years. A few syst...

Kenyon, S.; Murdin, P.

2000-11-01

133

Sea Stars  

NSDL National Science Digital Library

At first glance, starfish, more properly called sea stars, arenât doing much of anything. In this video, Jonathanâs investigations reveal a slow-motion predator that hunts and attacks its prey. Traveling the world, Jonathan investigates sea stars from the tropics to the Antarctic and uses time-lapse photography to reveal an amazing complexity to the world of the sea star. Please see the accompanying study guide for educational objectives and discussion points.

Productions, Jonathan B.

2010-10-06

134

The Graeme Bell All Stars: Play On  

Microsoft Academic Search

In the golden era of Australian jazz, the Graeme Bell Allstars were icons. From touring the globe to hosting their own television show, they captured the world with their music.\\u000aGraeme Bell came out of retirement at the age of 88 to reform his band. For over 3 years they enjoyed sold out performances and standing ovations at jazz festivals

Marco Ianniello

2006-01-01

135

Spectrophotometry of 237 Stars in 7 Open Clusters  

NASA Astrophysics Data System (ADS)

Spectrophotometry is presented for 237 stars in 7 nearby open clusters: Hyades, Pleiades, Alpha Persei, Praesepe, Coma Berenices, IC 4665, and M39. The observations were taken by Lee McDonald and David Burstein using the Wampler single-channel scanner on the Crossley 0.9m telescope at Lick Observatory from July 1973 through December 1974. Sixteen bandpasses spanning the spectral range 3500 Angstroms to 7780 Angstroms were observed for each star, with bandwidths 32Angstroms, 48 Angstroms or 64 Angstroms. Data are standardized to the Hayes-Latham system to mutual accuracy of 0.016 mag per passband. The accuracy of the spectrophotometry is assessed in three ways on a star-by-star basis. First, comparisons are made with previously published spectrophotometry for 19 stars observed in common. Second, (B-V) colors and uvby colors are compared for 236 stars and 221 stars, respectively. Finally, comparsions are made for 200 main sequence stars to the spectral synthesis models of Kurucz, fixing log g = 4.0 and [Fe/H] = 0.0, and only varying effective temperature. The accuracy of tests using uvby colors and the Kurucz models are shown to track each other closely, yielding an accuracy estimate (1 sigma ) of 0.01 mag for the 13 colors formed from bandpasses longward of the Balmer jump, and 0.02 mag for the 3 colors formed from the three bandpasses below the Balmer jump. In contrast, larger scatter is found relative to the previously published spectrophotometry of Bohm-Vitense & Johnson (16 stars in common) and Gunn & Stryker (3 stars). We also show that the scatter in the fits of the spectrophotometric colors and the uvby filter colors is a reasonable way to identify the observations of which specific stars are accurate to 1 sigma , 2 sigma , .... As such, the residuals from both the filter color fits and the Kurucz model fits are tabulated for each star where it was possible to make a comparison, so users of these data can choose stars according to the accuracy of the data that is appropriate to their needs. The very good agreement between the models and these data verifies the accuracy of these data, and also verifies the usefulness of the Kurucz models to define spectrophotometry for stars in this temperature range (>5000 K). These data define accurate spectrophotometry of bright, open cluster stars that can be used as a secondary flux calibration for CCD-based spectrophotometric surveys.

Clampitt, Lori; Burstein, David

1997-08-01

136

Lucky Star  

NSDL National Science Digital Library

Watch this video from Cyberchase and then play the Lucky Star game! The Lucky Star game show the will ask you math-related questions and give you four possible answers to choose from. Your goal is to answer the questions correctly and score as many points as you can. You can score points during two different rounds: the pick-a-star round and the lightning round. During the pick-a-star round you have as much time as you want to answer the questions. During the lightning round you have to think fast in order to earn the points. Good luck!

2008-01-01

137

Star Images, Star Performances (College Course File).  

ERIC Educational Resources Information Center

|Describes a course that focuses attention on the position of the actor, especially the star actor, in cinematic and television signification. Divides the course into three sections: "The Star System,""Stars as Images," and "Star Performance." (RS)|

Butler, Jeremy G.

1990-01-01

138

The effect of self-licking behavior on pharmacokinetics of eprinomectin and clinical efficacy against Psoroptes cuniculi in topically administered rabbits  

Microsoft Academic Search

Ear mange mite Psoroptes cuniculi, one of the predominant parasites in rabbits, can cause considerable weight loss, low favorable fee conversion rates, and\\u000a meningitis. The present experiment was to investigate the difference of plasma disposition and the variation of clinical efficacy\\u000a under the effect of animal self-licking behavior in topically administered rabbits. Ten rabbits for pharmacokinetic study\\u000a in two groups

Huiqiang Wen; Baoliang Pan; Fangfei Wang; Zhenzhong Yang; Zhujun Wang; Shuai Liu; Ming Wang

2010-01-01

139

One-trial simultaneous and backward excitatory fear conditioning in rats: Lick suppression, freezing, and rearing to CS compounds and their elements  

Microsoft Academic Search

Three experiments with rat subjects sought to enhance one-trial excitatory simultaneous and backward fear conditioning by\\u000a using a two-element compound conditioned stimulus (CS) instead of only a single element. During conditioning, experimental\\u000a groups received a 4-sec CS either coextensively with a 1-mA grid-shock unconditioned stimulus (US) or immediately after US\\u000a termination. In subsequent tests, CSs evoked more lick suppression and

Melody Albert; John J. B. Ayres

1997-01-01

140

Compact Stars  

NASA Astrophysics Data System (ADS)

Neutron stars are the smallest denses stars known, with densities some 1014 times that of the Earth. They rotate with periods of fractions of a second, and their magnetic fields drive intense interstellar dynamos, lighting up entire nebulae. This text discusses the physics of these extreme objects. It includes the needed background in classical general relativity in nuclear and particle physics.

Glendenning, Norman K.

141

Rogue Star  

NSDL National Science Digital Library

This program calculates and depicts the effects of a rogue star coming through our solar system. Users adjust the date, the rogue star's mass, approach distance in astronomical units (AU) and flyby speed to run an animation of what would happen to the planets under the specified conditions.

Hamilton, Douglas

142

Star Journey  

NSDL National Science Digital Library

This National Geographic web-site contains information about the Hubble Space Telescope (HST) along with a star chart and facts about objects in the night sky. The HST section contains details about the building and structure of the HST, how it captures light, positioning the HST to targets, instruments used to record and measure infrared through UV wavelengths, how the HST is powered and communicates with the Earth. Star Attractions discusses properties of constellations, the Milky Way galaxy, other galaxies, star clusters and nebulae. This information is then put together on the National Geographic Star Chart. This chart contains maps of the heavens for the northern and southern hemispheres. The chart contains constellation names, location of stars and other objects, and links to HST images of various galaxies and objects on the chart with names and detailed descriptions. There is an image index to find HST images from the site, details about chart symbol meanings, and links for more information.

Anderson, Carolyn

143

RESULTS OF THE LICK OBSERVATORY SUPERNOVA SEARCH FOLLOW-UP PHOTOMETRY PROGRAM: BVRI LIGHT CURVES OF 165 TYPE Ia SUPERNOVAE  

SciTech Connect

We present BVRI light curves of 165 Type Ia supernovae (SNe Ia) from the Lick Observatory Supernova Search follow-up photometry program from 1998 through 2008. Our light curves are typically well sampled (cadence of 3-4 days) with an average of 21 photometry epochs. We describe our monitoring campaign and the photometry reduction pipeline that we have developed. Comparing our data set to that of Hicken et al., with which we have 69 overlapping supernovae (SNe), we find that as an ensemble the photometry is consistent, with only small overall systematic differences, although individual SNe may differ by as much as 0.1 mag, and occasionally even more. Such disagreement in specific cases can have significant implications for combining future large data sets. We present an analysis of our light curves which includes template fits of light-curve shape parameters useful for calibrating SNe Ia as distance indicators. Assuming the B - V color of SNe Ia at 35 days past maximum light can be presented as the convolution of an intrinsic Gaussian component and a decaying exponential attributed to host-galaxy reddening, we derive an intrinsic scatter of {sigma} = 0.076 {+-} 0.019 mag, consistent with the Lira-Phillips law. This is the first of two papers, the second of which will present a cosmological analysis of the data presented herein.

Ganeshalingam, Mohan; Li Weidong; Filippenko, Alexei V.; Anderson, Carmen; Foster, Griffin; Griffith, Christopher V.; Joubert, Niels; Leja, Joel; Macomber, Brent; Pritchard, Tyler; Thrasher, Patrick; Winslow, Dustin [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor L.; Grigsby, Bryant J.; Lowe, Thomas B. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States)

2010-10-15

144

Maternal licking regulates hippocampal glucocorticoid receptor transcription through a thyroid hormone-serotonin-NGFI-A signalling cascade  

PubMed Central

Variations in parental care direct phenotypic development across many species. Variations in maternal pup licking/grooming (LG) in the rat regulate the development of individual differences in hypothalamic–pituitary–adrenal responses to stress. The adult offspring of mothers that show an increased frequency of pup LG have increased hippocampal glucocorticoid receptor (GR) expression and more modest pituitary–adrenal responses to stress. This parental effect is mediated by the epigenetic programming of a GR exon 1 promoter (exon 17) through the binding of the transcription factor nerve growth factor-inducible factor A (NGFI-A). In this paper, we report that: (i) the association of NGFI-A with the exon 17 GR promoter is dynamically regulated by mother–pup interactions; (ii) this effect is mimicked by artificial tactile stimulation comparable to that provided by pup LG; (iii) that serotonin (5-HT) induces an NGFI-A-dependent increase in GR transcription in hippocampal neurons and NGFI-A overexpression is sufficient for this effect; and (iv) that thyroid hormones and 5-HT are key mediators of the effects of pup LG and tactile stimulation on NGFI-A binding to the exon 17 GR promoter in hippocampus. These findings suggest that pup LG directly activates 5-HT systems to initiate intracellular signalling pathways in the hippocampus that regulate GR transcription.

Hellstrom, Ian C.; Dhir, Sabine K.; Diorio, Josie C.; Meaney, Michael J.

2012-01-01

145

Manganese Abundances in Globular Cluster and Halo Field Stars  

NASA Astrophysics Data System (ADS)

We have derived Mn abundances for more than 100 stars in nine Galactic globular clusters: M3, M4, M5, M10, M13, M15, M71, Pal5 and NGC 7006. In addition, Mn abundance determinations have been made for a comparable number of halo field stars possessing an overlapping range of metallicities and stellar parameters. The spectra of the cluster giants were obtained as a part of the Lick-Texas investigations into globular cluster chemistry. The spectra of the field stars are a part of a large study by Simmerer et al. (2004, ApJ, submitted). Data were collected at the McDonald, Lick ,and Keck Observatories and were analyzed using the synthetic spectra of the 6000 Å Mn I triplet. Hyperfine structure parameters were included in the synthetic spectra computations. It is well known that metal-poor field stars possess [Mn/Fe] ratios approximately a factor of two lower than solar values (Wallerstein et al. 1963, Gratton et al.1989, McWilliam et al. 1997). Our analysis shows that for the metallicity range -0.5 > [Fe/H] > -2.8 field stars have a mean relative abundance of <[Mn/Fe]> = -0.28±0.01 (sigma = 0.08), a value esssentially identical to that of the nine globular clusters: <[Mn/Fe]> = -0.28±0.01 (sigma = 0.12). It is evident that [Mn/Fe] ratios of metal-poor stars do not depend upon their environment. Our Mn abundance results viewed in conjunction with the globular cluster Cu abundances of Simmerer et al. (2003) suggest the following possibilities: one, the production of these elements is extremely metallicity-dependent or two, these elements were manufactured in the Galactic halo prior to cluster formation. Ongoing support from NSF, currently through grants AST-0307495 to CS and AST-0098453 to RPK, is gratefully acknowledged. Research for III is currently supported by NASA through Hubble Fellowship grant HST-HF-01151.01-A from the Space Telescope Science Institute.

Sobeck, J. S.; Simmerer, J. A.; Fulbright, J. P.; Sneden, C.; Kraft, R. P.; Ivans, I. I.

2004-05-01

146

Stars equilibrium  

NSDL National Science Digital Library

What causes the fusion reaction in a star's core? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to processes inside a star. Students read about the equilibrium process in a star, in which outward gas pressure equals inward gravitational pressure. Then, an interactive lab activity offers students the opportunity to predict temperature, pressure, and gravity changes that occur during equilibrium. The chemical reactions of the fusion process are presented, and more specific detailed reactions are available in a pop-up box. Student practice quizzes about the equilibrium process and pressure and gravity interactions inside the star are included, as are answers. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

147

Van Gogh's Starry Nights, Lincoln's Moon, Shakespeare's Stars, and More: Tales of Astronomy in Art, History, and Literature  

NASA Astrophysics Data System (ADS)

How do astronomical methods make it possible to calculate dates and times for Vincent van Gogh's night-sky paintings? Why is there a blood-red sky in Edvard Munch's The Scream? How can the 18.6-year cycle of the lunar nodes and the Moon's declination on the night of August 29-30, 1857, explain a long-standing mystery about Abraham Lincoln's honesty in the murder case known as the almanac trial? Why is a bright star described in Act 1, Scene 1, of Hamlet? There is a long tradition of astronomical methods employed to analyze works of art, to understand historical events, and to elucidate passages in literature. Both Edmond Halley and George Biddell Airy calculated lunar phases and tide tables in attempts to determine the landing beach where Julius Caesar invaded Britain in 55 B.C. Henry Norris Russell computed configurations of Jupiter and Saturn to determine a date for a 14th-century celestial event mentioned in Chaucer's Troilus and Criseyde. In this tradition, our Texas State group has published a series of articles in Sky & Telescope over the last two decades, applying astronomy to art, history, and literature. Don Osterbrock worked with us 3 years ago when my students and I calculated dates for moonrise photographs taken by Ansel Adams in Yosemite National Park. The peaks of the Sierra Nevada crest in Yosemite are more than 125 miles from Lick Observatory, but the mountains can become visible from Lick on clear winter days and were photographed from there on early infrared-sensitive plates during the 1920s and 1930s. As we tested our topographic software by identifying the peaks that appear in the Lick plates, it was a pleasure to come to know Don, a former director of Lick Observatory and the person in whose honor this talk is dedicated.

Olson, Donald W.

2009-01-01

148

THE LICK AGN MONITORING PROJECT 2011: DYNAMICAL MODELING OF THE BROAD-LINE REGION IN Mrk 50  

SciTech Connect

We present dynamical modeling of the broad-line region (BLR) in the Seyfert 1 galaxy Mrk 50 using reverberation mapping data taken as part of the Lick AGN Monitoring Project (LAMP) 2011. We model the reverberation mapping data directly, constraining the geometry and kinematics of the BLR, as well as deriving a black hole mass estimate that does not depend on a normalizing factor or virial coefficient. We find that the geometry of the BLR in Mrk 50 is a nearly face-on thick disk, with a mean radius of 9.6{sup +1.2}{sub -0.9} light days, a width of the BLR of 6.9{sup +1.2}{sub -1.1} light days, and a disk opening angle of 25 {+-} 10 deg above the plane. We also constrain the inclination angle to be 9{sup +7}{sub -5} deg, close to face-on. Finally, the black hole mass of Mrk 50 is inferred to be log{sub 10}(M{sub BH}/M{sub Sun }) = 7.57{sup +0.44}{sub -0.27}. By comparison to the virial black hole mass estimate from traditional reverberation mapping analysis, we find the normalizing constant (virial coefficient) to be log{sub 10} f = 0.78{sup +0.44}{sub -0.27}, consistent with the commonly adopted mean value of 0.74 based on aligning the M{sub BH}-{sigma}* relation for active galactic nuclei and quiescent galaxies. While our dynamical model includes the possibility of a net inflow or outflow in the BLR, we cannot distinguish between these two scenarios.

Pancoast, Anna; Brewer, Brendon J.; Treu, Tommaso; Bennert, Vardha N.; Sand, David J. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Barth, Aaron J.; Cooper, Michael C. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697-4575 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li, Weidong; Cenko, S. Bradley; Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor L. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Stern, Daniel; Assef, Roberto J. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Boulevard, Pasadena, CA 91109 (United States); Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Bae, Hyun-Jin [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of); Buehler, Tabitha, E-mail: pancoast@physics.ucsb.edu [Department of Physics and Astronomy, N283 ESC, Brigham Young University, Provo, UT 84602-4360 (United States); and others

2012-07-20

149

Neutron Stars and Quark Stars  

NASA Astrophysics Data System (ADS)

The tremendous densities reached in the centers of neutron stars provide a high pressure environment in which exciting particles processes are likely compete with each other and novel phases of matter may exist. The particle processes range from the generation of hyperons, to quark deconfinement, to the formation of kaon condensates and H-matter. Another striking possibility concerns the formation of absolutely stable strange quark matter. In the latter event all neutron stars could in fact be strange (quark matter) stars, which would be largely composed of pure quark matter possibly enveloped in a thin nuclear crust made up ordinary hadronic matter. This paper gives an overview of the properties of both classes of stars.

Weber, Fridolin

2004-08-01

150

A survey of the central-star characteristics of mostly faint planetary nebulae  

NASA Astrophysics Data System (ADS)

From a survey of 70 planetary nebulae whose spectra have been studied with the image-tube scanner (ITS) at the Shane 3-m telescope of Lick Observatory, the authors assess the characteristics of the central stars. About two dozen appear to have central stars with continuous spectra; a slightly large number is classified as weak-emission-line objects with N III, C III, and C IV lines; seven are of the Wolf-Rayet type. Most of the observed objects lie in the direction of the galactic bulge; the others were scattered in galactic longitude to the anticenter. There appears to be no evidence for a systematic concentration of the types with respect to galactic longitude.

Aller, L. H.; Keyes, C. D.

1985-12-01

151

Proper Motions of 8790 Stars with Ref. to Galaxies (Klemola+ 1971)  

NASA Astrophysics Data System (ADS)

Proper motions are given for 7978 stars measured with reference to the system of galaxies are presented. The proper motions are based on two series of plates taken with the 20-inch Carnegie Astrograph of the Lick Observatory at epochs separated on the average by 19.2 years. There are 83 fields with an average of 56 galaxies per field. The mean error of the reference frame affects the proper motion in each coordinate by an average amount of 0.16"/cen. The mean error of an individual proper motion is about 0.7"/cen. in each coordinate, and that of a blue magnitude is about 0.2mag. The file contains a running number for each field, an AGK3 or Yale Zone number and magnitude, if available, the X and Y coordinates of the star on the first epoch plates, and the type of image measured and the proper motions and magnitudes from this project.

Klemola, A. R.; Vasilevskis, S.; Shane, C. D.; Wirtanen, C. A.

2000-02-01

152

Chameleon stars  

SciTech Connect

We consider a gravitating spherically symmetric configuration consisting of a scalar field nonminimally coupled to ordinary matter in the form of a perfect fluid. For this system we find static, regular, asymptotically flat solutions for both relativistic and nonrelativistic cases. It is shown that the presence of the nonminimal interaction leads to substantial changes both in the radial matter distribution of the star and in the star's total mass. A simple stability test indicates that, for the choice of parameters used in the paper, the solutions are unstable.

Dzhunushaliev, Vladimir [Institute for Basic Research, Eurasian National University, Astana, 010008 (Kazakhstan); Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Folomeev, Vladimir [Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Singleton, Douglas [Institute for Basic Research, Eurasian National University, Astana, 010008 (Kazakhstan); Physics Department, CSU Fresno, Fresno, California 93740-8031 (United States)

2011-10-15

153

Manganese Abundances in Globular Cluster and Halo Field Stars  

NASA Astrophysics Data System (ADS)

We have derived Mn abundances for more than 100 stars in eleven Galactic globular clusters: M3 (NGC 5272), M4 (NGC 6121), M5 (NGC 5904), M10 (NGC 6254), M13 (NGC 6205), M15 (NGC 7078), M71 (6838), M92 (6341), Pal5, Pal 12 and NGC 7006. In addition, Mn abundance determinations have been made for a comparable number of halo field stars possessing an overlapping range of metallicities and stellar parameters. Data were collected at the McDonald, Lick and Keck Observatories and were analyzed using synthetic spectra of the 6000 Å Mn I triplet. Hyperfine structure parameters were included in the synthetic spectra computations. Our analysis shows that for the metallicity range -0.8 > [Fe/H] > -2.7 field stars have a mean relative abundance of <[Mn/Fe]> = -0.27±0.01 (? = 0.08), a value essentially identical to that of the eleven globular clusters: <[Mn/Fe]> = -0.28±0.01 (? = 0.12). Our Mn abundance results viewed in conjunction with the globular cluster Cu abundances of Simmerer et al. (2003) suggest the following possibilities: one, the production of these elements is extremely metallicity-dependent or two, these elements were manufactured in the Galactic halo prior to cluster formation.

Sobeck, J. S.; Simmerer, J. A.; Fulbright, J. P.; Sneden, C.; Kraft, R. P.; Ivans, I. I.

2005-09-01

154

Variable Stars  

NASA Astrophysics Data System (ADS)

It is a tradition to observe variable stars using small telescopes; actually, variable stars are the favorites of small telescopes. What it is needed is those telescopes to be well-equipped (to get good observations), and to be supplied with users (to be productive). The first can be easily achieved; the second, related to the poor job prospects, seems more difficult. Keeping in mind that there is no any Observatory, that could cover the whole sky and that an astronomical event can not be repeated, each individual observation, is very valuable. Especially that of variable stars, where the variability of their luminosity can be caused by many reasons, intrinsic or extrinsic. What is missing -from at least some of the small telescopes spread in whole Europe- is better organization. This means that, besides either some research projects of personal interest, or(/and) students training, some others -being parts of international programs- could also be carried out, focusing to specific objects and goals. The work carried out in the field of variable stars with the use of small telescopes in some European countries, will be presented.

Rovithis-Livaniou, Helen

155

Brittle Star  

USGS Multimedia Gallery

A tiny brittle star (the central disc is smaller than a dime) clings to the branches of a soft coral in a sample bucket brought into the shipboard laboratory from a submersible dive. This creature makes its home on the deep, dark ocean floor. ...

2010-04-15

156

Star quality.  

PubMed

Around 150 wards are participating in the voluntary Star Wards scheme to provide mental health inpatients with more activities with therapeutic value. Suggested activities range from a library, to horse riding Internet access and comedy. Service users are particularly keen to have more exercise, which can be a challenge in inpatient settings. PMID:17970387

Dent, Emma

2007-09-20

157

RETIRED A STARS AND THEIR COMPANIONS. III. COMPARING THE MASS-PERIOD DISTRIBUTIONS OF PLANETS AROUND A-TYPE STARS AND SUN-LIKE STARS  

SciTech Connect

We present an analysis of approx5 years of Lick Observatory radial velocity measurements targeting a uniform sample of 31 intermediate-mass (IM) subgiants (1.5 approx< M{sub *}/M{sub sun}approx< 2.0) with the goal of measuring the occurrence rate of Jovian planets around (evolved) A-type stars and comparing the distributions of their orbital and physical characteristics to those of planets around Sun-like stars. We provide updated orbital solutions incorporating new radial velocity measurements for five known planet-hosting stars in our sample; uncertainties in the fitted parameters are assessed using a Markov-Chain Monte Carlo method. The frequency of Jovian planets interior to 3 AU is 26{sup +9}{sub -8}%, which is significantly higher than the 5%-10% frequency observed around solar-mass stars. The median detection threshold for our sample includes minimum masses down to left brace0.2, 0.3, 0.5, 0.6, 1.3right brace M{sub Jup} within left brace0.1, 0.3, 0.6, 1.0, 3.0right brace AU. To compare the properties of planets around IM stars to those around solar-mass stars we synthesize a population of planets based on the parametric relationship dN propor to M {sup a}lpha P {sup b}eta dlnMdlnP, the observed planet frequency, and the detection limits we derived. We find that the values of alpha and beta for planets around solar-type stars from Cumming et al. fail to reproduce the observed properties of planets in our sample at the 4sigma level, even when accounting for the different planet occurrence rates. Thus, the properties of planets around A stars are markedly different than those around Sun-like stars, suggesting that only a small (approx50%) increase in stellar mass has a large influence on the formation and orbital evolution of planets.

Bowler, Brendan P.; Johnson, John Asher; Liu, Michael C. [Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Marcy, Geoffrey W.; Peek, Kathryn M. G. [Department of Astronomy, University of California, MS 3411, Berkeley, CA 94720-3411 (United States); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Blvd., Box 9501, Nashville, TN 37209 (United States); Fischer, Debra A.; Clubb, Kelsey I. [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States); Reffert, Sabine; Schwab, Christian [ZAH-Landessternwarte, Koenigstuhl 12, 69117 Heidelberg (Germany); Lowe, Thomas B., E-mail: bpbowler@ifa.hawaii.ed [UCO/Lick Observatory, Santa Cruz, CA 95064 (United States)

2010-01-20

158

Stars : the end of a star  

NSDL National Science Digital Library

What happens during the death of a star? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the final processes of stars. Here students read about low-mass, medium-mass, and massive stars. Low-mass stars produce white dwarfs. A pop-up window describes how white dwarfs form. Medium-mass stars produce neutron stars and supernova. Pop-up information explains the supernova process. Massive stars undergo carbon burning. An interactive lab activity presents students the opportunity to predict temperature, pressure, and gravity changes that occur during carbon fusion. In a final lab activity, students compare initial star size with the type of death that occurs. Activity questions about star death are provided for each star size and are recordable and printable. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

159

Evolution of Galaxies- Star Formation Histories in Nearby Spheroids  

NASA Astrophysics Data System (ADS)

This thesis is about an investigation into the formation of spheroidal type galaxies. The investigation began with modelling studies of early-type galaxies and spiral bulges (SBs). From galaxy formation modelling studies led by experiments with a sample galaxy, some results were obtained; non-solar abundance ratios in Elliptical galaxies (Es) achieved better fits between model and data than solar abundance ratios. For both early-type and late-type galaxies, best fits with non-solar abundance ratios were more constrained than in the solar abundance ratio case. A strong link between star formation histories and the supernova Ia rate for the early and late-type galaxies was shown. The model code itself was tested by way of pseudo galaxy experiments, and shown to reliably reproduce model parameters. In the topic area of galaxy formation, regions of spectra particularly sensitive to a galaxy's age and metallicity were measured as equivalent widths and then calibrated to the common scale of the Lick Indices. The Lick Indices were used in deriving all key results throughout the thesis. The modelled sample of galaxies from Proctor & Sansom (2002) lacked data on low velocity dispersion (?) galaxies for line strengths versus kinematics correlations. In regards to low ? galaxies, Low Luminosity Es (LLEs) were considered to be likely candidates. Long-slit spectra of a sample of 12 LLEs, taken at the European Southern Observatory New Technology Telescope, were sub-selected for their low velocity dispersions. The spectra of 10 of these LLEs were successfully reduced. Line strengths and kinematics were measured. The Lick Indices of these LLEs were correlated with velocity dispersion (?), alongside the previously modelled companion data set. Ages and metallicities of the LLEs were estimated. From these results, the LLEs were found to have significant correlations of line strength versus ? with SBs. However, the LLEs do not appear to be younger than SBs, but younger than Es. The LLEs seem to consist of a low metallicity group (possibly misclassified dwarf spheroidal galaxies) and a high metallicity group. Future possible work that may uncover which models of galaxy formation for high and low metallicity LLEs these results support is suggested.

Northeast, M.

160

Death Star  

NSDL National Science Digital Library

Death Star, a program from the PBS NOVA series, probes the deep mysteries of gamma-ray bursts, the most powerful celestial explosions since the Big Bang. A description of what would happen to Earth if a gamma-ray burst occurred in our own galaxy, a celestial glossary, and a virtual tour of the electromagnetic spectrum are included. Additional websites and published works about space topics are given, and the accompanying video is available to order.

161

Symbiotic Stars  

NASA Astrophysics Data System (ADS)

Symbiotic stars are interacting binary systems composed of a white dwarf (WD) accreting at high rate from a cool giant companion, which frequently fills its Roche lobe. The WD usually is extremely hot and luminous, and able to ionize a sizeable fraction of the cool giant wind, because it is believed the WD undergoes stable hydrogen nuclear burning on its surface of the material accreted from the companion. This leads to consider symbiotic stars as good candidates for the yet-to-be-identified progenitors of type Ia supernovae. Symbiotic stars display the simultaneous presence of many different types of variability, induced by the cool giant, the accreting WD, the circumstellar dust and ionized gas, with time scales ranging from seconds to decades. The long orbital periods (typically a couple of years) and complex outburst patterns, lasting from a few years to a century, make observations from professionals almost impossible to carry out, and open great opportunities to amateur astronomers to contribute fundamental data to science.

Munari, U.

2012-06-01

162

Exceptional Stars  

NASA Astrophysics Data System (ADS)

As part of our Interdisciplinary Scientist effort (PI, Kulkarni) for the Space Interferometry Mission (SIM) we proposed an investigation with SIM of a number of exceptional stars. With SIM we plan to observe dozens of nearby white dwarfs and search for planets surviving the evolution away from the main sequence as well as (newly formed) planets formed in the circumbinary disks of post-AGB binaries or as a result of white dwarf mergers. We propose to measure the proper motion of a sample of X-ray binaries and Be star binaries with the view of understanding the originof high latitude objects and inferring natal kicks and pre-supernova orbits. We plan to observe several compact object binaries to determine the mass of the compact star. Of particular importance is the proposed observation of SS 433 (for which we propose to use the spectrometer on SIM to measure the proper motion of the emission line clumps embedded in the relativistic jets). Separately we are investigating the issue of frame tie between SIM and the ecliptic frame (by observing binary millisecond pulsars with SIM; the position of these objects is very well determined by pulsar timing) and the degree to which highly precise visibility amplitude measurements can be inverted to infer binary parameters.

Kulkarni, S. R.; Hansen, B.; van Kerkwijk, M.; Phinney, E. S.

2005-12-01

163

True-sky demonstration of an autonomous star tracker  

NASA Astrophysics Data System (ADS)

An autonomous star tracker (AST) is basically a `star field in, attitude out' device capable of determining its attitude without requiring any a priori attitude knowledge. In addition to this attitude acquisition capability, an AST can perform attitude updates autonomously and is able to provide its attitude `continuously' while tracking a star field. The Lockheed Palo Alto Research Laboratory is developing a reliable, low-cost, miniature AST that has a one arcsec overall accuracy, weighs less than 1.5 kg, consumes less than 7 watts of power, and is sufficiently sensitive to be used at all sky locations. The device performs attitude acquisition in a fraction of a second and outputs its attitude at a 10 Hz rate when operating in its tracking mode. Besides providing the functionality needed for future advanced attitude control and navigation systems, an AST also improves spacecraft reliability, mass, power, cost, and operating expenses. The AST comprises a-thermalized, refractive optics, a frame-transfer CCD with a sensitive area of 1024 by 1024 pixels, camera electronics implemented with application- specific integrated circuits, a compact single board computer with a radiation hard 32 bit RISC processor, and an all-sky guide star database. Star identification is performed by a memory- efficient and highly robust algorithm that finds the largest group of observed stars matching a group of guide stars. An important milestone has recently been achieved with the validation of the attitude acquisition capability through correct and rapid identification of all 704 true-sky star fields obtained at the Lick Observatory, using an uncalibrated prototype AST with a 512 by 1024 pixel frame-transfer CCD and a 50 mm f/1.2 lens that provided an effective 6.5 by 13.2 degree field of view. The overlapping fields cover 47% of the sky, including both rich and sparse areas. The paper contains a description of the AST, a summary of the functions enabled or improved by the device, an overview of the identification algorithm, results obtained with a realistic simulation program, a description of the true-sky star field identification method and a presentation of the results obtained. The AST tolerates the presence of bright objects as was demonstrated by a field that included Jupiter.

van Bezooijen, Roelof W.

1994-07-01

164

The AP stars  

Microsoft Academic Search

Ap stars are stars with peculiar characteristics which made it difficult to assign them to the stellar types of the conventional classification scheme. Ap stars are frequently observed. Up to 10% Ap stars are found in the case of the concerned spectral types. Attention is given to the spectroscopic properties of the Ap stars, aspects of stellar spectrum and stellar

H. Muthsam

1977-01-01

165

Star formation in disks  

Microsoft Academic Search

It is noted that the principal characteristics of the stellar populations in galaxies depend on the history of star formation and the initial mass spectrum with which the stars are formed. Whereas there have been a number of attempts to model the history of star formation in galaxies using various quasi-theoretical descriptions of star formation, star formation remains poorly understood

R. B. Larson

1983-01-01

166

Observations of comet P/Shoemaker-Levy 9 impact on Jupiter from Lick Obseravtory using a high resolution speckle imaging camera  

SciTech Connect

During the week of the impacts of Comet Shoemaker-Levy 9 into Jupiter, we used a speckle imaging camera mounted on the Lick Observatory 3 meter Telescope to record a continuous stream of images of the planet. Because the speckle imaging technique compensates for atmospheric blurring, the resulting images were most likely the highest resolution of any taken from the ground. These images compliment the Hubble Space Telescope data by covering time periods when Hubble was not observing Jupiter. We collected full planet 1024 by 1024 pixel CCD images taken 20 per minute for 4 hours per night over 6 nights July 15 to 22. Only a portion of this raw data has been reduced to high resolution images to date.

Max, C.; Gavel, D.; Johansson, E.; Sherwood, B.; Liu, M.; Bradford, B.

1996-03-15

167

RW Tauri as a weak W Serpentis star  

NASA Astrophysics Data System (ADS)

Observations of the short-period eclipsing binary RW Tau made with the LWR and SWP cameras of the IUE satellite and with the ITS scanner at the 3-m Shane telescope of the Lick Observatory in August and October, 1982, are reported and analyzed. At total eclipse, weak excess continuous radiation in the LWR range and emission lines at Si IV (1), C IV (1), Al III (1), Fe III (34), and Mg II (1) in the SWP range were detected. These findings are similar to those for W Ser-type binaries such as U Cep. The parameters of the system are estimated using a bilinearly interpolated atmospheric model of the type developed by Kurucz (1979): primary-star T(eff) = 11,750 K, log g = 4.2, cool-component spectral type = K0 III, E(B-V) color excess = 0.14 mag, system distance = 270 pc. The implications of these findings for proposed models of the W Ser binaries are discussed, and the observation of a possible distant optical companion star 45 arcsec from RW Tau is reported.

Plavec, M. J.; Dobias, J. J.

1983-09-01

168

Proper motions of field HB stars (Sakamoto+, 2003)  

NASA Astrophysics Data System (ADS)

We set new limits on the mass of the Milky Way, making use of the latest kinematic information for Galactic satellites and halo objects. Our sample consists of 11 satellite galaxies, 137 globular clusters, and 413 field horizontal-branch (FHB) stars up to distances of 10kpc from the Sun. Roughly half of the objects in this sample have measured proper motions, permitting the use of their full space motions in our analysis. The field horizontal branch stars presented in table1 was created from the list of Wilhelm 1999 (J/AJ/117/2329) as the source of magnitudes, radial velocities and [Fe/H]; the proper motions were extracted from one or more proper-motion catalogs: STARNET Catalog (Roeser 1996), Yale-San Juan Southern Proper Motion Catalog (SPM 2.0: Platais et al. 1998, Cat. I/283), Lick Northern Proper Motion Catalog (NPM1: Klemola et al. 1994, Cat. I/199), and TYCHO-2 Catalog (Hog et al. 2000, Cat. I/259). (1 data file).

Sakamoto, T.; Chiba, M.; Beers, T. C.

2002-11-01

169

Lifestyles of the Stars.  

ERIC Educational Resources Information Center

|Some general information on stars is provided in this National Aeronautics and Space Administration pamphlet. Topic areas briefly discussed are: (1) the birth of a star; (2) main sequence stars; (3) red giants; (4) white dwarfs; (5) neutron stars; (6) supernovae; (7) pulsars; and (8) black holes. (JN)|

National Aeronautics and Space Administration, Cocoa Beach, FL. John F. Kennedy Space Center.

170

Theories of star formation  

Microsoft Academic Search

A well defined theory of star formation does not yet exist. A serious deficiency therefore remains in current theories of the structure and evolution of stars. Since stars must be forming at the present phase of Galactic evolution, it is pertinent to investigate what conditions favour star formation. Observational evidence for the pre-main sequence phase of stellar evolution is entirely

D. McNally

1971-01-01

171

Extragalactic Star Clusters: the Resolved Star Approach  

NASA Astrophysics Data System (ADS)

The physical processes leading to the dissolution of star clusters is a topic barely studied and still not understood. We started a pilot project to develop a new approach to directly detect and study the properties of stellar clusters while they are being destroyed. Our technique currently under development makes use of the exceptional spatial resolution and sensitivity of the ACS camera onboard HST to resolve individual stars in nearby galaxies. PSF stellar photometry and color-magnitude diagrams allows us to separate the most massive stars (more likely to be in clusters) from the star field background. While applying the method to the normal spiral galaxy NGC1313, we found that the method of studying star clusters through resolved stars in nearby galaxies is even more powerful than we first expected. The stellar maps obtained for NGC1313 show that a large fraction of early B-type stars contained in the galaxy are already part of the star field background rather that being in star clusters. Such stars live for 5 to 25 Myr. Since most stars form in clusters, the presence of such massive stars in the field means that they must have left their birthplace very rapidly. It also means that the processes involved in the dissolution of the clusters are extremely efficient. The only plausible explanation for so many young stars to be in the field background is the infant mortality of star clusters. We will present the latest results on the two galaxies NGC 1313 and IC 2475 and discuss the potential of the new approach for studying extragalactic stellar clusters.

Pellerin, Anne; Meyer, M. J.; Jason, H.; Calzetti, D.

2006-12-01

172

Herschel's Star Gages  

NSDL National Science Digital Library

The EJS Herschel's Star Gages Model illustrates William Herschel's methods of "star gages" by which he attempted to map out the shape of our galaxy in 1785. Herschel's star gages (sic) relied on two important assumptions: that Herschel's telescope (his "large 20 foot" with an 18.5 inch aperture) could see to the ends of the galaxy, and that within the galactic system stars are distributed uniformly. If the first assumption holds then the stars seen in the telescope all lie within a conical region of space with the apex at the telescope and the base at the edge of the galaxy. If the second assumption holds then the number of stars seen in the telescope is proportional to the volume of this cone. Since the volume of the cone is proportional to the cube of its height, the distance to the galactic edge in any direction is proportional to the cube root of the number of stars seen in that direction. This simulation allows the user to use Herschel's method of star gages to map out the shape of an artificial "star system" for which Herschel's assumptions are valid. One window shows the view through a telescope, with a slider to change the telescopes direction (around a single fixed axis). Another window shows a 3D view of the star system, showing either all of the stars in the system or only those stars visible through the telescope. A third window shows a plot of the star gages. Plotting star gages for many different directions maps out a cross-section of the star system. An optional slider allows the user to decrease the distance to at which stars are no longer visible, and a menu allows the user to select a star system in which the stars are not distributed uniformly. These options let the user explore how violations of Herschel's two fundamental assumptions invalidate his star gage method.

Timberlake, Todd

2011-05-28

173

Star Formation in Galaxies  

NASA Astrophysics Data System (ADS)

The process of star formation is at the core of the evolutionary cycle of galaxies, as newborn stars produce new chemical elements, dust, and light. The energetic output delivered first by stellar winds and then by supernovae a few Myr after a star formation episode may also directly impact on the evolution of galaxies and their interstellar medium (ISM), as well as having an effect on the intergalactic medium (IGM), through feedback and outflows.This chapter concerns star formation on galactic scales. First, the galactic processes that may affect large-scale star formation are presented. Second, the various methods to measure star formation rates are discussed (star formation tracers, timescales, calibrations, limits). Finally, the observational status concerning star formation in galaxies (its relation to other quantities and its evolution) is presented. The Schmidt Law (star formation rate-gas relationship) is amply discussed.

Boissier, Samuel

174

14 CFR 91.145 - Management of aircraft operations in the vicinity of aerial demonstrations and major sporting...  

Code of Federal Regulations, 2013 CFR

...Team (Golden Knights); (4) Summer/Winter Olympic Games; (5) Annual Tournament of Roses Football Game; (6) World Cup Soccer; (7) Major League Baseball All-Star Game; (8) World Series; (9) Kodak Albuquerque...

2013-01-01

175

National Organ and Tissue Donation Initiative  

MedlinePLUS

... this animated video to see what happens during organ donation and transplantation, how someone becomes a donor, and ... Alonzo Mourning: NBA All-Star OPOs Recognized for Organ Donation Outreach Sharing Hope and Life Donation For People ...

176

Who Really Coined the Word Supernova? Who First Predicted Neutron Stars?  

NASA Astrophysics Data System (ADS)

The answer to both questions is Walter Baade and Fritz Zwicky. They used the word and postulated that the remnants could be neutron stars in the abstract of their joint paper ``Supernovae and Cosmic Rays," presented orally by Zwicky at an American Physical Society meeting at Stanford in December 1933. The abstract was published in the Physical Review in early 1934, and was a condensation of their two joint papers in PNAS in 1934. The concept that there is a special class of ``much more luminous novae" (Lundmark 1923), which we today call supernovae, was put forward by Knut Lundmark (1920), who called them ``giant novae," and independently by Heber D. Curtis (1921). Hubble (1929) referred to them as ``exceptional novae," and Baade (1929), writing in German, as ``Hauptnovae" (chief novae). According to a review article by Zwicky (1940), he and Baade introduced the term supernovae in seminars and an astrophysics course at Caltech in 1931. Lundmark (1933) actually first published the word (as ``super-Novae") in a paper dated December 31, 1932 but published in 1933. He was at Lick and Mount Wilson during the fall and winter of 1932-33, and it is much more probable that he heard it there than that he coined it himself. In their abstract and PNAS papers Baade and Zwicky ``advanced the view" that supernovae represent the collapse of ``ordinary stars into neutron stars," because that gave about the right total energy released in the outburst. Many physicists believe that Lev Landau (1932) had introduced this concept, but actually his paper is about relativistically degenerate stars and does not mention neutrons, neutron stars, nor a density. Freeman Dyson (1971) in his published lectures on neutron stars and pulsars correctly credited the concept to Baade and Zwicky (1934). Extracts from these and other related papers will be posted.

Osterbrock, D. E.

2001-12-01

177

A Conceptual Design Study for an Upgraded Dual-Channel Near-Infrared Imager/Spectrometer at the Shane 3m Telescope at Lick Observatory  

NASA Astrophysics Data System (ADS)

A wide variety of astrophysical sources (cool brown dwarfs and exoplanets, obscured Galactic regions, high redshift SN/GRBs) are only accessible and/or characterizable at near-infrared (NIR) wavelengths. The development and declining costs of wide-format NIR detectors makes their use on 3-5m class telescopes for survey and synoptic studies an increasingly viable option. We describe a conceptual design study for a multichannel, NIR imager/spectrometer for the Shane 3m telescope at Lick Observatory, aimed to replace the existing Gemini camera (McLean et al. 1993). We perform a scientific cost/benefit analysis of various instrumentation features, including: tradeoffs in field-of-view, angular resolution and sensitivity; tradeoffs in long-wavelength detector cutoffs, cooling requirements and site environment; filter complement; capability for multiple dichroic options; inclusion of grism spectroscopy and polarimetry capabilities, and the option of a third optical (CCD) channel. We also examine these considerations in the context of existing 1-5m class NIR instrumentation, and identify areas in which the proposed instrument would enable unique and novel science.

Bowsher, Emily C.; Burgasser, A.

2011-05-01

178

Carlsberg Meridian Catalogues, La Palma. Numbers 1 - 11, 1999. Observations of positions of stars and planets, May 1984 to May 1998 including extinction and meteorological data.  

NASA Astrophysics Data System (ADS)

This composite catalogue contains 180812 positions and magnitudes of 176591 stars north of declination -40°, 155005 proper motions, and 25848 positions and magnitudes of 184 Solar System objects obtained with the Carlsberg Automatic Meridian Circle on La Palma during the period May 1984 to May 1998. It includes CMC1 - 11; i.e. it comprises all the observations made with the moving-slit micrometer since the instrument began operation on La Palma. The positions of the stars are for the epoch of observation and the equinox J2000.0, and are referred to the new International Celestial Reference Frame. The limiting magnitude is V = 15.4. The catalogue mainly comprises observations and proper motions for the following programmes: 36000 International Reference Stars, 30000 faint reference stars in a global net, 18000 reference stars in the fields of radio sources, 17000 stars in the Lick Northern Proper Motion catalogue, 5000 reference stars for calibration of Schmidt plates, 2600 stars in the Gliese catalogue of nearby stars, 5000 stars in nearby OB associations, 10500 F-type stars within 100 pc, 9000 G-type d&g, K-type g stars within 300 pc, 2200 unbiased sample of K/M-typed stars, 19400 reference stars near Veron-Cetty galaxies, 4700 variable stars (12 - 14 mag) in GCVS, 12400 stars (11 - 14 mag) with pm > 0?-18/yr in NLTT, and several smaller programmes mainly aimed at galactic kinematics. Positions and magnitudes of 12 novae and 8 supernovae which occurred in the years 1991 to 1998 are included. The catalogue also contains observations of the following Solar System objects: Callisto, Ganymede, Rhea, Titan, Iapetus, Hyperion, Uranus, Oberon, Neptune, Pluto and 173 minor planets and comet P/Wild 2. The mean error of a catalogue position in the zenith is 0-09 in right ascension and declination in CMC1 - 6, improving to 0-06 in CMC7 - 11. The accuracy in magnitude is 0.05 mag in CMC1 - 10, improving to 0.03 mag in CMC11. The mean error of the proper motions, derived by combining the position in this catalogue with those at earlier epochs, is typically in the range 0??003 to 0??004 per year. Cross-references are given to DM, AGK, SAO, HD and the Washington Double Star catalogues. The catalogue also contains 12216 mean annual observed positions of the FK5 stars used to transfer the instrumental system to the FK5 frame in the years 1984 - 1995. A compilation of all the meteorological data collected in the years 1984 - 1998, including the atmospheric extinction, is appended.

179

Astronomy: A Star Party  

NSDL National Science Digital Library

This lesson is designed to teach students about the functions of a telescope, the daylight uses of a telescope, the parts of the telescope, and to identify and view certain stars and planets during a star party at night.

180

Quark core stars, quark stars and strange stars  

SciTech Connect

A recent one flavor quark matter equation of state is generalized to several flavors. It is shown that quarks undergo a first order phase transition. In addition, this equation of state depends on just one parameter in the two flavor case, two parameters in the three flavor case, and these parameters are constrained by phenomenology. This equation of state is then applied to the hadron-quark transition in neutron stars and the determination of quark star stability, the investigation of strange matter stability and possible strange star existence. 43 refs., 6 figs.

Grassi, F.

1988-01-01

181

Star formation in irregular galaxies  

Microsoft Academic Search

The problems associated with star formation in irregular galaxies are outlined. The basic model of star formation is reviewed. Global star formation rates, feedback processes, the physical conditions of the interstellar medium which affect star formation, and the internal structures of star-forming regions in irregular galaxies are discussed. In addition, star formation in the amorphous irregular galaxies described by Sandage

D. A. Hunter; J. S. Gallagher III

1989-01-01

182

QCD in Neutron Stars and Strange Stars  

SciTech Connect

This paper provides an overview of the possible role of Quantum Chromo Dynamics (QCD) for neutron stars and strange stars. The fundamental degrees of freedom of QCD are quarks, which may exist as unconfined (color superconducting) particles in the cores of neutron stars. There is also the theoretical possibility that a significantly large number of up, down, and strange quarks may settle down in a new state of matter known as strange quark matter, which, by hypothesis, could be more stable than even the most stable atomic nucleus, {sup 56}Fe. In the latter case new classes of self-bound, color superconducting objects, ranging from strange quark nuggets to strange quark stars, should exist. The properties of such objects will be reviewed along with the possible existence of deconfined quarks in neutron stars. Implications for observational astrophysics are pointed out.

Weber, Fridolin [Department of Physics, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-1233 (United States); Negreiros, Rodrigo [FIAS, Goethe University, Ruth Moufang Str 1, 60438 Frankfurt (Germany)

2011-05-24

183

Managing the star performer.  

PubMed

Our culture seems to be endlessly fascinated with its stars in entertainment, athletics, politics, and business, and holds fast to the idea that extraordinary talent accounts for an individual's extraordinary performance. At first glance, managing a star performer in your medical practice may seem like it would be an easy task. However, there's much more to managing a star performer than many practice managers realize. The concern is how to keep the star performer happy and functioning at a high level without detriment to the rest of the medical practice team. This article offers tips for practice managers who manage star performers. It explores ways to keep the star performer motivated, while at the same time helping the star performer to meld into the existing medical practice team. This article suggests strategies for redefining the star performer's role, for holding the star performer accountable for his or her behavior, and for coaching the star performer. Finally, this article offers practical tips for keeping the star performer during trying times, for identifying and cultivating new star performers, and for managing medical practice prima donnas. PMID:23767124

Hills, Laura

184

Superbursts from Strange Stars  

Microsoft Academic Search

Recent models of carbon ignition on accreting neutron stars predict superburst ignition depths that are an order of magnitude larger than those observed. We explore a possible solution to this problem, that the compact stars in low-mass X-ray binaries that have shown superbursts are in fact strange stars with a crust of normal matter. We calculate the properties of superbursts

Dany Page; Andrew Cumming

2005-01-01

185

Dark Stars: D\\\\  

Microsoft Academic Search

The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the universe. This and the previous contribution present the story of Dark Stars.

Douglas Spolyar; Katherine Freese; Paolo Gondolo; Anthony Aguirre; Peter Bodenheimer; Jeremy A. Sellwood; Naoki Yoshida

2009-01-01

186

Dark Stars: Begynnelsen  

Microsoft Academic Search

The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the universe. This and the following contribution present the story of Dark Stars.

Paolo Gondolo; Katherine Freese; Douglas Spolyar; Anthony Aguirre; Peter Bodenheimer; Jeremy A. Sellwood; Naoki Yoshida

2009-01-01

187

The Neutron Star Census  

Microsoft Academic Search

The paucity of old isolated accreting neutron stars in ROSAT observations is used to derive a lower limit on the mean velocity of neutron stars at birth. The secular evolution of the population is simulated following the paths of a statistical sample of stars for different values of the initial kick velocity, drawn from an isotropic Gaussian distribution with mean

S. B. Popov; M. Colpi; A. Treves; R. Turolla; V. M. Lipunov; M. E. Prokhorov

2000-01-01

188

Star Formation in Galaxies  

Microsoft Academic Search

Star formation on a galactic scale is regulated by the self-gravity of the gas, as shown by the Jeans-length spacing of giant cloud complexes along spiral arms and the sensitivity of the star formation rate to the gravitational stability parameter Q. Simple models based on this scenario reproduce the general properties of galactic star formation in both normal and starburst

B. G. Elmegreen

1999-01-01

189

Theory of Star Formation  

Microsoft Academic Search

We review current understanding of star formation, outlining an overall theoretical framework and the observations that motivate it. A conception of star formation has emerged in which turbulence plays a dual role, both creating overdensities to initiate gravitational contraction or collapse, and countering the effects of gravity in these overdense regions. The key dynamical processes involved in star formation---turbulence, magnetic

Christopher F. McKee; Eve C. Ostriker

2007-01-01

190

Analyzing Star Trails  

NSDL National Science Digital Library

In this activity, students examine a photograph of the night sky and answer questions about their observations. The picture, taken by a high school student in upstate New York, offers insight into the Earth's rotation, apparent star motion, the location of Polaris (the North Star), circumpolar constellations, and pointer stars.

Kluge, Steve

191

Star Trail Photography  

NSDL National Science Digital Library

This web page contains information about taking photographs of star trails, which illustrate the rotation of the Earth. The site provides techniques to take successful star trail photos, including a technique using a series of short exposures and assembling them with computer software. Techniques for including foreground images of ground objects are given. Examples of star trail photos are provided.

Peiker, E. J.

2007-10-15

192

Eclipsing Binary Stars  

NSDL National Science Digital Library

Eclipsing Binary Stars model simulates the detection of eclipsing binary stars. In this method, the light curve from the combination of the two stars, and how it changes over time due to each star transiting (or being occulted or eclipsing the other), is observed and then analyzed. In this simulation each star orbits the other in circular motion via Kepler's third law.  When one star passes in front of the other (transits), it blocks part of the starlight of the other star. This decrease in starlight is shown on the graph.  In the simulation the binary star system is shown as seen from Earth (edge on view) and from overhead, but magnified greatly, and with the star sizes not shown to the scale of the orbit. The mass, radius, and temperature of each star can be changed. The simulation uses either simple 3D or Java 3D (if installed) to render the view the stars. If Java 3D is not installed, the simulation defaults to simple 3D using Java. The Eclipsing Binary Stars model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_eclipsing_binaries.jar file will run the program if Java is installed.

Belloni, Mario

2010-07-15

193

THE LICK-CARNEGIE EXOPLANET SURVEY: A URANUS-MASS FOURTH PLANET FOR GJ 876 IN AN EXTRASOLAR LAPLACE CONFIGURATION  

SciTech Connect

Continued radial velocity (RV) monitoring of the nearby M4V red dwarf star GJ 876 with Keck/High Resolution Echelle Spectrograph has revealed the presence of a Uranus-mass fourth planetary companion in the system. The new planet has a mean period of P{sub e} = 126.6 days (over the 12.6-year baseline of the RV observations), and a minimum mass of m{sub e} sin i{sub e} = 12.9 {+-} 1.7 M {sub +}. The detection of the new planet has been enabled by significant improvements to our RV data set for GJ 876. The data have been augmented by 36 new high-precision measurements taken over the past five years. In addition, the precision of all of the Doppler measurements have been significantly improved by the incorporation of a high signal-to-noise template spectrum for GJ 876 into the analysis pipeline. Implementation of the new template spectrum improves the internal rms errors for the velocity measurements taken during 1998-2005 from 4.1 m s{sup -1} to 2.5 m s{sup -1}. Self-consistent, N-body fits to the RV data set show that the four-planet system has an invariable plane with an inclination relative to the plane of the sky of i = 59.{sup 0}5. The fit is not significantly improved by the introduction of a mutual inclination between the planets 'b' and 'c', but the new data do confirm a non-zero eccentricity, e{sub d} = 0.207 {+-} 0.055 for the innermost planet, 'd'. In our best-fit coplanar model, the mass of the new component is m{sub e} = 14.6 {+-} 1.7 M {sub +}. Our best-fitting model places the new planet in a three-body resonance with the previously known giant planets (which have mean periods of P{sub c} = 30.4 and P{sub b} = 61.1 days). The critical argument, {psi}{sub Laplace} = {lambda} {sub c} - 3{lambda} {sub b} + 2{lambda} {sub e}, for the Laplace resonance librates with an amplitude of {Delta}{psi}{sub Laplace} = 40{sup 0} {+-} 13{sup 0} about {psi}{sub Laplace} = 0{sup 0}. Numerical integration indicates that the four-planet system is stable for at least a billion years (at least for the coplanar cases). This resonant configuration of three giant planets orbiting an M dwarf primary differs from the well-known Laplace configuration of the three inner Galilean satellites of Jupiter, which are executing very small librations about {psi}{sub Laplace} = 180{sup 0} and which never experience triple conjunctions. The GJ 876 system, by contrast, comes close to a triple conjunction between the outer three planets once per every orbit of the outer planet, 'e'.

Rivera, Eugenio J.; Laughlin, Gregory; Vogt, Steven S.; Meschiari, Stefano [UCO/Lick Observatory, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Butler, R. Paul [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington DC, 20015-1305 (United States); Haghighipour, Nader, E-mail: rivera@ucolick.or [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Monoa, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

2010-08-10

194

The Lick-Carnegie Exoplanet Survey: a Uranus-Mass Fourth Planet for GJ 876 in an Extrasolar Laplace Configuration  

NASA Astrophysics Data System (ADS)

Continued radial velocity (RV) monitoring of the nearby M4V red dwarf star GJ 876 with Keck/High Resolution Echelle Spectrograph has revealed the presence of a Uranus-mass fourth planetary companion in the system. The new planet has a mean period of Pe = 126.6 days (over the 12.6-year baseline of the RV observations), and a minimum mass of me sin ie = 12.9 ± 1.7 M ?. The detection of the new planet has been enabled by significant improvements to our RV data set for GJ 876. The data have been augmented by 36 new high-precision measurements taken over the past five years. In addition, the precision of all of the Doppler measurements have been significantly improved by the incorporation of a high signal-to-noise template spectrum for GJ 876 into the analysis pipeline. Implementation of the new template spectrum improves the internal rms errors for the velocity measurements taken during 1998-2005 from 4.1 m s-1 to 2.5 m s-1. Self-consistent, N-body fits to the RV data set show that the four-planet system has an invariable plane with an inclination relative to the plane of the sky of i = 59fdg5. The fit is not significantly improved by the introduction of a mutual inclination between the planets "b" and "c," but the new data do confirm a non-zero eccentricity, ed = 0.207 ± 0.055 for the innermost planet, "d." In our best-fit coplanar model, the mass of the new component is me = 14.6 ± 1.7 M ?. Our best-fitting model places the new planet in a three-body resonance with the previously known giant planets (which have mean periods of Pc = 30.4 and Pb = 61.1 days). The critical argument, phivLaplace = ? c - 3? b + 2? e , for the Laplace resonance librates with an amplitude of ?phivLaplace = 40° ± 13° about phivLaplace = 0°. Numerical integration indicates that the four-planet system is stable for at least a billion years (at least for the coplanar cases). This resonant configuration of three giant planets orbiting an M dwarf primary differs from the well-known Laplace configuration of the three inner Galilean satellites of Jupiter, which are executing very small librations about phivLaplace = 180° and which never experience triple conjunctions. The GJ 876 system, by contrast, comes close to a triple conjunction between the outer three planets once per every orbit of the outer planet, "e." Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology.

Rivera, Eugenio J.; Laughlin, Gregory; Butler, R. Paul; Vogt, Steven S.; Haghighipour, Nader; Meschiari, Stefano

2010-08-01

195

Aeronautics Learning Laboratory for Science, Technology, and Research (ALLSTAR).  

National Technical Information Service (NTIS)

We finished the material development of Level 1, Level 2 and most of Level 3. We created three new galleries, one of streaming videos enabling the user to select his/her appropriate speed of Internet connectivity for better performance. The second gallery...

C. Levy M. A. Ebadian

1998-01-01

196

Evolution of variable stars  

SciTech Connect

Throughout the domain of the H R diagram lie groupings of stars whose luminosity varies with time. These variable stars can be classified based on their observed properties into distinct types such as ..beta.. Cephei stars, delta Cephei stars, and Miras, as well as many other categories. The underlying mechanism for the variability is generally felt to be due to four different causes: geometric effects, rotation, eruptive processes, and pulsation. In this review the focus will be on pulsation variables and how the theory of stellar evolution can be used to explain how the various regions of variability on the H R diagram are populated. To this end a generalized discussion of the evolutionary behavior of a massive star, an intermediate mass star, and a low mass star will be presented. 19 refs., 1 fig., 1 tab.

Becker, S.A.

1986-08-01

197

Stars main sequence  

NSDL National Science Digital Library

What happens during most of a star's life? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the main sequence phase of a star's existence. This phase is where a star lives out the majority of its life. In an interactive lab activity, students predict the length of the main sequence for four different stars. The predictions can be printed for later evaluation. Students view diagrams that compare the size and color of stars to human lives, and equilibrium within a star is stressed. Finally, students choose between two hypotheses about the length of life of a star. Students write a one- to three-sentence explanation for their hypotheses. The correct answer is provided. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

198

Toward Understanding the B[e] Phenomenon. II. New Galactic FS CMa Stars  

NASA Astrophysics Data System (ADS)

FS CMa stars form a group of objects with the B[e] phenomenon that were previously known as unclassified B[e] stars or B[e] stars with warm dust (B[e]WD) until recently. They exhibit strong emission-line spectra and strong IR excesses, most likely due to recently formed circumstellar dust. These properties have been suggested to be due to ongoing or recent rapid mass exchange in binary systems with hot primaries and various types of secondaries. The first paper of this series reported an analysis of the available information about previously known Galactic objects with the B[e] phenomenon, the initial selection of the FS CMa group objects, and a qualitative explanation of their properties. This paper reports the results of our new search for more FS CMa objects in the IRAS Point Source Catalog. We present new photometric criteria for identifying FS CMa stars as well as the first results of our observations of nine new FS CMa group members. With this addition, the FS CMa group has now 40 members, becoming the largest among the dust-forming hot star groups. We also present nine objects with no evidence for the B[e] phenomenon, but with newly discovered spectral line emission and/or strong IR excesses. Partially based on data obtained at the 6 m BTA Telescope of the Russian Academy of Sciences, 3.6 m Canada-France-Hawaii Telescope, 3 m Shane Telescope of the Lick Observatory, 2.7 m Harlan J. Smith and 2.1 m Otto Struve Telescopes of the McDonald Observatory, 2.1 m telescope of the San Pedro Martir Observatory, 1.5 m telescope of the Loiano Observatory, and 0.8 m telescope of the Dark Sky Observatory.

Miroshnichenko, A. S.; Manset, N.; Kusakin, A. V.; Chentsov, E. L.; Klochkova, V. G.; Zharikov, S. V.; Gray, R. O.; Grankin, K. N.; Gandet, T. L.; Bjorkman, K. S.; Rudy, R. J.; Lynch, D. K.; Venturini, C. C.; Mazuk, S.; Puetter, R. C.; Perry, R. B.; Levato, H.; Grosso, M.; Bernabei, S.; Polcaro, V. F.; Viotti, R. F.; Norci, L.; Kuratov, K. S.

2007-12-01

199

Massive stars, disks, and clustered star formation  

NASA Astrophysics Data System (ADS)

The formation of an isolated massive star is inherently more complex than the relatively well-understood collapse of an isolated, low-mass star. The dense, clustered environment where massive stars are predominantly found further complicates the picture, and suggests that interactions with other stars may play an important role in the early life of these objects. In this thesis we present the results of numerical hydrodynamic experiments investigating interactions between a massive protostar and its lower-mass cluster siblings. We explore the impact of these interactions on the orientation of disks and outflows, which are potentially observable indications of encounters during the formation of a star. We show that these encounters efficiently form eccentric binary systems, and in clusters similar to Orion they occur frequently enough to contribute to the high multiplicity of massive stars. We suggest that the massive protostar in Cepheus A is currently undergoing a series of interactions, and present simulations tailored to that system. We also apply the numerical techniques used in the massive star investigations to a much lower-mass regime, the formation of planetary systems around Solar- mass stars. We perform a small number of illustrative planet-planet scattering experiments, which have been used to explain the eccentricity distribution of extrasolar planets. We add the complication of a remnant gas disk, and show that this feature has the potential to stabilize the system against strong encounters between planets. We present preliminary simulations of Bondi-Hoyle accretion onto a protoplanetary disk, and consider the impact of the flow on the disk properties as well as the impact of the disk on the accretion flow.

Moeckel, Nickolas Barry

200

Star Show Classroom Activity  

NSDL National Science Digital Library

In this lesson from Math Machines, the class will "plan and conduct a simulated astronomical observing session to photgraph a variety of star types." The instructor will set up several "stars" around the classroom, and students will then set up a telescope location and estimate the altitude and azimuth to photograph each star. A participant handout (including worksheet) and facilitator notes are made available for download in DOC file format. Links to calculator programs are also included.

Thomas, Fred

2011-11-03

201

Dark Stars: D\\\\\\  

Microsoft Academic Search

The first phase of stellar evolution in the history of the universe may be\\u000aDark Stars, powered by dark matter heating rather than by fusion. Weakly\\u000ainteracting massive particles, which are their own antiparticles, can\\u000aannihilate and provide an important heat source for the first stars in the\\u000auniverse. This and the previous contribution present the story of Dark Stars.

Douglas Spolyar; Katherine Freese; Paolo Gondolo; Anthony Aguirre; Peter Bodenheimer; Jeremy A. Sellwood; Naoki Yoshida

2009-01-01

202

The Neutron Stars Census  

Microsoft Academic Search

The paucity of old isolated accreting neutron stars in ROSAT observations is\\u000aused to derive a lower limit on the mean velocity of neutron stars at birth.\\u000aThe secular evolution of the population is simulated following the paths of a\\u000astatistical sample of stars for different values of the initial kick velocity,\\u000adrawn from an isotropic Gaussian distribution with mean

S. B. Popov; M. Colpi; A. Treves; R. Turolla; V. M. Lipunov; M. E. Prokhorov

1999-01-01

203

Impulsively Triggered Star Formation  

Microsoft Academic Search

I review several different modes of impulsively triggered star formation, starting with star formation in turbulent molecular\\u000a clouds, and exploring the origin of the clump mass function and the scaling relations between clump mass, radius and internal\\u000a velocity dispersion. This leads to the identification of a critical ram pres-sure for triggering rapid star formation, and\\u000a a reappraisal of the minimum

A. P. Whitworth

2003-01-01

204

Preliminary Map Star Catalog  

NASA Astrophysics Data System (ADS)

As part of an ongoing study, the Allegheny Observatory is in the process of measuring high precision, (1 milliarcsec), parallaxes and proper motions for approximately 900 stars selected at random in the northern sky. The spectral type of these stars is also being determined from UBVRI, uvby, H-Beta, and DDO photometry. This catalog represents a unique and complete statistical set of data for 900 stars of visual magnitude 6-12. A preliminary catalog will be presented.

Persinger, T.; Gatewood, G.; Castelaz, M.

1995-05-01

205

Our Super Star  

NSDL National Science Digital Library

Our star, the Sun, is an ordinary star. It is not particularly special compared to other stars in the universe; however, it is crucially important to us. As the massive energy source at the center of our solar system, the Sun is responsible for Earth's climate, weather, and life. In this lesson, students use observations, activities, and videos to learn basic facts about the Sun. Students also model the mechanics of day and night and use solar energy to make a tasty treat.

Foundation, Wgbh E.

2009-07-10

206

Star Trek Generations  

NSDL National Science Digital Library

Paramount Pictures and Viacom Online have developed a World Wide Web site to herald the upcoming motion picture Star Trek Generations. The site offers a galaxy of unique Star Trek elements for downloading, including pictures, sounds and a preview of the movie, in addition to behind-the-scenes information. Make sure to give Paramount "Your Input"- all respondents will receive a digital version of the Star Trek Generations movie poster

207

Delta Scuti stars: Theory  

SciTech Connect

The purpose of asteroseismology is not only to derive the internal structure of individual stars from their observed oscillation frequencies, but also to test and extend one`s understanding of the physics of matter under the extremes of temperature, density, and pressure found in stellar interiors. In this review, the author hopes to point out what one can learn about the Sun by studying {delta} Scuti stars, as well as what one can learn about stars more massive or evolved than the Sun. He discusses some of the difficulties in theoretical approaches to asteroseismology for {delta} Scuti stars, using FG Vir, {delta} Scuti, and CD-24{degree} 7599 as examples.

Guzik, J.A.

1998-03-01

208

Global Star Formation Revisited  

NASA Astrophysics Data System (ADS)

A general treatment of disk star formation is developed from a dissipative multiphase model, with the dominant dissipation due to cloud collisions. The Schmidt-Kennicutt (SK) law emerges naturally for star-forming disks and starbursts. We predict that there should be an inverse correlation between Tully-Fisher law and SK law residuals. The model is extended to include a multiphase treatment of supernova feedback that leads to a turbulent pressure-regulated generalization of the star formation law and is applicable to gas-rich starbursts. Enhanced pressure, as expected in merger-induced star formation, enhances star formation efficiency. An upper limit is derived for the disk star formation rate in starbursts that depends on the ratio of global ISM to cloud pressures. We extend these considerations to the case where the interstellar gas pressure in the inner galaxy is dominated by outflows from a central active galactic nucleus (AGN). During massive spheroid formation, AGN-driven winds trigger star formation, resulting in enhanced supernova feedback and outflows. The outflows are comparable to the AGN-boosted star formation rate and saturate in the super-Eddington limit. Downsizing of both SMBH and spheroids is a consequence of AGN-driven positive feedback. Bondi accretion feeds the central black hole with a specific accretion rate that is proportional to the black hole mass. AGN-enhanced star formation is mediated by turbulent pressure and relates spheroid star formation rate to black hole accretion rate. The relation between black hole mass and spheroid velocity dispersion has a coefficient (Salpeter time to gas consumption time ratio) that provides an arrow of time. Highly efficient, AGN-boosted star formation can occur at high redshift.

Silk, Joseph; Norman, Colin

2009-07-01

209

A Comprehensive Examination of Several Symbiotic Stars.  

NASA Astrophysics Data System (ADS)

Contemporaneous observations of five northern symbiotic stars with the IUE satellite and Lick ITS throughout the spectral range 1200 - 8000 A. are analyzed. The objects studied are AG Pegasi, AG Draconis, YY Herculis, V443 Herculis, and RW Hydrae. Late component spectral types, emitting region electron temperatures and densities, hot component Zanstra temperatures, and stellar parameters are determined. All of the objects studied appear to be binaries. Photoionization is, in all cases except possibly AG Dra, the energy input mechanism. Our object, YY Her, appears to be embedded in a disk-like structure of accreting material. Electron densities in the emitting region characterized by the ultraviolet intercombination lines of N III}, O IV}, and O III} are in the range 1 x 10('9) to 5 x 10('10). These values are considerably higher than those seen in planetary nebulae and gaseous H II regions and are a factor of 100 or so higher than crude estimates made from optical region features. The mean electron temperatures characteristic of the {O III} and N V emitting zones range between 9000 K. and 20,000 K. The hot components of all the objects are well below the main sequence, indeed, and He II Zanstra temperatures of all the hot components are on the order of 100,000 K. With the possible exception of AG Dra, the hot component ultraviolet spectrum is probably not produced by nuclear burning of a thin hydrogen shell of material accreted onto a white dwarf as suggested by Paczynski and Rudak (1980). The supercritical wind accretion disk model of Bath (1977) may operate, especially in YY Her, but the accreting component must be a subdwarf in AG Peg, the system for which we have performed the most detailed analysis. Furthermore, accretion fueled by mass transfer via Roche lobe overflow does not appear to be currently occurring in AG Peg and, possibly, AG Dra. No information is available for RW Hya. At least one system, AG Peg, appears to be an evolved object in or near the second stage of mass transfer, however, the AG Peg slow nova outburst may not have been the result of a planetary nebula-like shell ejection episode. We quite often see bound-free and free-free emission from the nebular regions in these systems. Variations of this emission seem to account for most of the observed optical region brightness fluctuations. This emission contributes strongly in the satellite ultraviolet so that the hot component may not always be seen directly. Therefore, simple model atmosphere continuum-fitting procedures should be regarded with extreme caution.

Keyes, Charles Dayton

210

Effects of supplementary urea-minerals lick block on the kinetics of fibre digestion, nutrient digestibility and nitrogen utilization of low quality roughages*  

PubMed Central

Three yearling lambs with a rumen cannula were used to investigate the effects of supplementation with an urea-minerals lick block (ULB) on the kinetics of ruminal fibre digestion, nutrient digestibility and nitrogen (N) utilization of rice straw (RS), ammonia bicarbonate (AB)-treated RS (ABRS) and hay prepared from natural pasture. The digestibility of dry matter and organic matter of RS increased by 13.1% and 12.7% (P<0.05) when the diet was supplemented with ULB, and approached to that of ABRS, indicating that the effect of ULB on digestibility of RS is similar to that of AB treatment. The digestibility of ABRS was slightly improved by the ULB feeding. Nitrogen retention was highest in lambs fed on ABRS alone, followed by hay with ULB, and was lowest in animals fed on RS with ULB. However, both the amount and proportion of N retention to N intake were enhanced by ULB supplementation to lambs fed on hay. The proportion of N retained to N digested decreased due to ULB supplementation to lambs fed on RS or ABRS. Supplementing ULB did not greatly influence the rumen degradation of either dry matter or crude protein in each of the three diets. RS and hay had similar values in the potential extent of digestion (PED) and digestion rate of PED (kd) of fibrous materials, but the discrete lag time for RS was lower than that for hay. The AB treatment significantly increased the PED (P<0.05) and kd (P<0.05) of RS. Neither the PED nor kd for RS and ABRS was influenced by ULB supplementation, but the kd for hay significantly increased due to ULB. The lag time for hay was also shortened by the ULB feeding. The ULB improved the digestion of fibre in the rumen of lambs fed on low quality roughage. It is inferred that while ULB is effective in increasing nutrient digestibility of low quality roughages by improving ruminal fibre digestion. A synchronized supply of N and energy to rumen microbes should be considered to improve the efficiency of N utilization when the basal diet is ammoniated straw.

Wu, Yue-ming; Hu, Wei-lian; Liu, Jian-xin

2005-01-01

211

Observing Double Stars  

NASA Astrophysics Data System (ADS)

Double stars have been systematically observed since William Herschel initiated his program in 1779. In 1803 he reported that, to his surprise, many of the systems he had been observing for a quarter century were gravitationally bound binary stars. In 1830 the first binary orbital solution was obtained, leading eventually to the determination of stellar masses. Double star observations have been a prolific field, with observations and discoveries - often made by students and amateurs - routinely published in a number of specialized journals such as the Journal of Double Star Observations. All published double star observations from Herschel's to the present have been incorporated in the Washington Double Star Catalog. In addition to reviewing the history of visual double stars, we discuss four observational technologies and illustrate these with our own observational results from both California and Hawaii on telescopes ranging from small SCTs to the 2-meter Faulkes Telescope North on Haleakala. Two of these technologies are visual observations aimed primarily at published "hands-on" student science education, and CCD observations of both bright and very faint doubles. The other two are recent technologies that have launched a double star renaissance. These are lucky imaging and speckle interferometry, both of which can use electron-multiplying CCD cameras to allow short (30 ms or less) exposures that are read out at high speed with very low noise. Analysis of thousands of high speed exposures allows normal seeing limitations to be overcome so very close doubles can be accurately measured.

Genet, Russell M.; Fulton, B. J.; Bianco, Federica B.; Martinez, John; Baxter, John; Brewer, Mark; Carro, Joseph; Collins, Sarah; Estrada, Chris; Johnson, Jolyon; Salam, Akash; Wallen, Vera; Warren, Naomi; Smith, Thomas C.; Armstrong, James D.; McGaughey, Steve; Pye, John; Mohanan, Kakkala; Church, Rebecca

2012-05-01

212

Magnetism in Massive Stars  

NASA Astrophysics Data System (ADS)

Stars with mass more than 8 solar masses end their lives as neutron stars, which we mostly observe as highly magnetized objects. Where does this magnetic field come from? Such a field could be formed during the collapse, or is a (modified) remnant of a fossil field since the birth of the star, or otherwise generated by a dynamo during its lifetime in the pre-collapse stages. The answer is unknown, but traditionally magnetic massive stars should not exist since they do not have a convective layer such as the Sun. In the last decade, however, a number of magnetic massive stars have been found, which likely possess a stable field from their birth, and indirect evidence is accumulating that localized fields can indeed be generated during the main-sequence lifetime and beyond. These observational facts opened a new field of research, which is the topic of this review. Among the indirect evidence is a large range of observational phenomena among O and B stars that cannot be explained without the presence of surface magnetic fields. These phenomena include photospheric turbulence, wind clumping, cyclic wind variability observed in UV lines, other types of wind variability in optical lines, anomalous X-ray emission, and non-thermal emission in the radio region. A summary of the properties of observed magnetic massive OB stars is given and the role of magnetic fields in massive stars will be discussed, including how to identify new magnetic candidates.

Henrichs, H. F.

2012-12-01

213

Close triple star systems  

Microsoft Academic Search

Triple-star systems, especially those in which one star has very small mass, are examined. Observations that provide information about the physical nature of close systems, in particular, changes of the period of orbital revolution, are discussed. It is shown that the detection and study of these changes is best obtained by observations of the precise times of light minima in

F. B. Wood

1985-01-01

214

Hyperons in neutron stars  

SciTech Connect

Generalized beta equilibrium involving nucleons, hyperons, and isobars is examined for neutron star matter. The hyperons produce a considerable softening of the equation of state. It is shown that the observed masses of neutron stars can be used to settle a recent controversy concerning the nuclear compressibility. Compressibilities less than 200 MeV are incompatible with observed masses. 7 refs., 9 figs.

Glendenning, N.K.

1986-04-01

215

Carbon star effective temperatures  

Microsoft Academic Search

Possible methods for measuring the effective temperatures of individual carbon stars are discussed. Since calibrations of broad or narrow-band photometric colors is impractical at present, empirical corrections to narrow band color temperatures is the only valid procedure. The effective temperature of the star TW Oph is estimated, based on preliminary reduction of the occultation and associated photometry

S. T. Ridgway; G. H. Jacoby; R. R. Joyce; D. C. Wells

1981-01-01

216

The Violent Neutron Star  

NASA Astrophysics Data System (ADS)

Neutron stars enable us to study both the highest densities and the highest magnetic fields in the known Universe. In this article I review what can be learned about such fundamental physics using magnetar bursts. Both the instability mechanisms that trigger the bursts, and the subsequent dynamical and radiative response of the star, can be used to explore stellar and magnetospheric structure and composition.

Watts, A. L.

2012-12-01

217

Quarkonium at STAR.  

National Technical Information Service (NTIS)

The STAR detector is capable of reconstruction the J/(psi) meson in its dielectron decay channel, along with continuum dielectrons from heavy quark decay. The limitation is not instrumental--the ability of the STAR detector to identify electrons--rather, ...

T. J. LeCompte

1998-01-01

218

Stars for Navigation  

NASA Astrophysics Data System (ADS)

During World War II, stars were important navigation aids for pilots flying long night patrols. Several aspects of navigation by stars are discussed from personal experience by the author who flew Catalina aircraft over the ocean and North Africa during this period. This paper is based on a talk given to the Southland Astronomical Society.

Neave, Tom

2001-09-01

219

Party with the Stars.  

ERIC Educational Resources Information Center

|Describes a Star Party which involves comparing the different colors of the stars, demonstrating how astronomers measure the sky with degrees, determining the cardinal direction, discussing numerous stories that ancient civilizations gave to constellations, exercising science process skills, and using science instruments. (JRH)|

Blaine, Lloyd

1997-01-01

220

Build Your Own Star  

NSDL National Science Digital Library

This SEED website from Schlumberger provides a simulation of the life-cycle of a star. The user chooses the initial mass and "metal" (non-hydrogen/helium) content, and the site shows how the star evolves and ultimately how it dies. The site also explains "the most famous graph in astronomy," the H-R diagram.

2007-06-12

221

Why Observe Double Stars?  

NASA Astrophysics Data System (ADS)

Like many branches of astronomy, the observation of double stars can be appreciated 5 at several levels. For those who enjoy the night sky, double stars offer some of 6 the most attractive sights around and they are particularly good in small telescopes 7 where the colours are much more obvious.

Argyle, Bob; Argyle, R. W.

222

Metallicity and Ionization Balance in a Very Metal-Poor Galactic Halo Turnoff Star  

NASA Astrophysics Data System (ADS)

We have derived the iron metallicity of the very metal-poor main-sequence turnoff star HD 84937, using many Fe I and Fe II transitions over the largest wavelength range to date, 2300-7500A. The high resolution spectra for this work were taken with the Lick 3.0m Hamilton, the Magellan MIKE, and the Hubble Space Telescope STIS echelle spectrographs. From a standard LTE analysis, we derive metallicities for HD 84937 from both Fe I and Fe II lines that are consistent with literature values, [Fe/H] -2.2. These are the first results in our project to provide new abundances for many Fe-peak elements from their neutral and ionized species using both visible and UV wavelength data. HD 84937 provides a benchmark for assessing the departures from LTE ionization equilibria in cooler, lower gravity very metal-poor stars. This work has been supported by The University of Texas Astronomy Department Cox Undergraduate Excellence Fund to MAA, NSF grants AST-0607708, AST-0908978 to CS and AST-0707447 to JJC, and NASA Grant NNX08AQ09G to JEL.

Alvarez, Matthew; Sneden, C.; Fulbright, J.; Lawler, J. E.; Sobeck, J. S.; Cowan, J. J.

2010-01-01

223

Observing Variable Stars  

NASA Astrophysics Data System (ADS)

Observing variable stars is one of the major contributions amateur astronomers make to science. There are 36,000 variable stars listed in the General Catalogue of Variable Stars, so it is clearly impossible for the limited number of professional observatories to target even the majority of them. That's where amateur astronomers come in - thousands of them turning their telescopes to the sky every night. Variable star observing is the most popular of "real science" activities for amateurs, and Gerry Good's book provides everything needed. The first part of the book provides a highly detailed account of the various classes of variable star, with examples, illustrations and physical descriptions. The second section covers practical aspects of observing, everything from preparation and planning, through observing techniques, to data management and reduction.

Good, Gerry A.

224

Overexpression of neuropeptide Y in the dorsomedial hypothalamus increases trial initiation but does not significantly alter concentration-dependent licking to sucrose in a brief-access taste test.  

PubMed

Evidence in the literature raises the possibility that alterations in neuropeptide Y (NPY) in the dorsomedial hypothalamus (DMH) may contribute to hyperphagia leading to body weight gain. Previously, we have shown that compared to AAVGFP controls, adeno-associated virus (AAV)-mediated overexpression of NPY in the DMH of lean rats resulted in significantly higher body weight gain that was attributed to increased food intake, and this was further exacerbated by a high-fat diet. Here, we tested AAVNPY and AAVGFP control rats in a brief-access taste procedure (10-s trials, 30-min sessions) to an array of sucrose concentrations under ad libitum and partial food and water access conditions. The test allows for some segregation of the behavioral components by providing a measure of trial initiation (appetitive) and unconditioned licks at each concentration (consummatory). Consistent with previous findings suggesting that NPY has a primary effect on appetitive function, overexpression of DMH NPY did not significantly alter concentration-dependent licking response to sucrose but when tested in a non-restricted food and water schedule, AAVNPY rats initiated significantly more sucrose trials compared to AAVGFP controls in a brief-access taste test. PMID:23313404

Treesukosol, Yada; Bi, Sheng; Moran, Timothy H

2013-01-10

225

Computational Star Formation (IAU S270)  

NASA Astrophysics Data System (ADS)

1. Historical introduction; 2. Individual star formation: observations; 3. Low-mass star formation: observations; 4. Individual star formation: theory; 5. Formation of clusters: observations; 6. Formation of clusters: theory; 7. Numerical methods: MHD; 8. Numerical methods: radiative dynamics; 9. Local star formation processes; 10. Star formation feedback; 11. Star formation on galactic scales; 12. Special purpose hardware; 13. Computational methods; 14. Radiation diagnostics of star formation; 15. Large scale star formation; 16. Cosmological star formation; 17. Computational star formation: Summary; Index.

Alves, João.; Elmegreen, Bruce G.; Girart, Josep M.; Trimble, Virginia

2011-05-01

226

Scope on the Skies: Star light, star bright  

NSDL National Science Digital Library

In astronomy, the brightness of a star is described in terms of a star's magnitude. Stellar magnitude is expressed two different ways, using the terms apparent magnitude and absolute magnitude . For both magnitudes, the numbering scale is the same, with negative numbers being brighter stars and positive numbers being dimmer stars. This month's column sheds light on the stars and how astronomers measure distances to these celestial objects.

Riddle, Bob

2009-03-01

227

The Constellations and their Stars  

NSDL National Science Digital Library

This website is a tutorial on constellations and the stars in them. It offers an alphabetical and monthly listing of the constellations. It also provides a listing of stars, messier objects, and a list of the brightest stars in the sky. The user can also use the website's interactive star chart, Milky Way photos, or helpful links.

Dolan, Chris

2005-05-15

228

Infrared studies of star formation  

Microsoft Academic Search

Infrared observations at wavelengths of a few microns to 1 mm are reviewed which pertain to the problem of star formation. The data considered include observations of large gas and dust clouds within which stars may be forming and detailed studies of individual objects within these clouds. Stages of star formation are outlined, the IR luminosity of forming stars is

M. W. Werner; E. E. Becklin; G. Neugebauer

1977-01-01

229

Lithium in stars with exoplanets  

Microsoft Academic Search

Our recent study of solar-type stars from the HARPS GTO sample provides highly accurate information with regard to Lithium abundances in stars with and without detected planets (Israelian et al. 2009). When the Li abundances of planet bearing stars are compared with the ``single'' stars, we find an excess of Li depletion in planet hosts with effective temperatures in the

Garik Israelian

2010-01-01

230

Visual Binary Star Observations  

NASA Astrophysics Data System (ADS)

A special mathematics course (MAT298AC) was offered in the fall 2010 and spring 2011 semesters at the Estrella Mountain Community College (EMCC), providing students the opportunity to gain real-world experience through observations, applied mathematics and research techniques. The students and instructor in MAT298AC chose to pursue visual binary star observations with the goal of contributing to the scientific knowledge base. Visual observations of selected binary stars were obtained by utilizing EMCC campus astronomical equipment. Data collected includes the separation of potential binary stars and their position angle.

Darling, Kodiak; Diaz, Kristy; Lucas, Arriz; Santo, Travis; Walker, Douglas

2011-05-01

231

Possible Nova among Hyades stars  

NASA Astrophysics Data System (ADS)

A new(?) very red 6th mag star was discovered among the stars of the Hyades from images obtained on 2012 October 22 04:28 EDT (10:28 UT). The coordinates of the star are RA,Dec (J2000.0): 04:23:29, +17:58:29 (+/-10"). This position is 2.23 arcmin south of the star GSC 1268-1045; and although this faint (13th mag) star does not appear on the discovery images, it is not believed to be the new star. Follow-up observations, especially spectroscopy are very desirable to confirm the presence and nature of the new star.

Shelton, Ian

2012-10-01

232

Variable star data online  

NASA Astrophysics Data System (ADS)

Roger Pickard, Andy Wilson and Gary Poyner describe the online database of the British Astronomical Association Variable Star Section, a treasure trove of observations stretching back nearly 125 years.

Pickard, Roger; Wilson, Andy; Poyner, Gary

2012-06-01

233

Detector limitations, STAR.  

National Technical Information Service (NTIS)

Every detector has limitations in terms of solid angle, particular technologies chosen, cracks due to mechanical structure, etc. If all of the presently planned parts of STAR (Solenoidal Tracker At RHIC) were in place, these factors would not seriously li...

D. G. Underwood

1998-01-01

234

Cosmions and stars  

SciTech Connect

Hypothetical particles such as the heavy neutrino, the photino, or the sneutrino/emdash/generically called cosmions/emdash/may solve the so called missing mass problem. If they exist, the cosmions may close the Universe. In addition to their gravitational effect on cosmological scales, the cosmions may also be captured by stars and concentrate in their cores. Since cosmions are able to transport heat outside stellar cores much more efficiently than photons, they may seriously affect the thermodynamics of the inner layer of stars. We have done an exact calculation of the accretion rate of cosmions by main sequence stars and we have studied the suppression of their central convection. We concluded that central convection inside stars between 0.3 Msub solar and 1 Msub solar is broken in the presence of cosmions. 6 refs., 2 figs.

Salati, P.

1987-12-01

235

Structure of Neutron Stars.  

National Technical Information Service (NTIS)

Structure of neutron stars consisting of a cold and catalyzed superdense matter were investigated by integrating the equations for hydrostatic equilibrium based on the General Relativity theory. The equations of state were obtained with the help of semiem...

C. K. Cheong

1974-01-01

236

Inside a Star . . .  

ERIC Educational Resources Information Center

|Describes classroom activities to understand the evolution of elements as it occurs in the stars. Activities can be undertaken in groups. Explicit instructions and background materials are included. (PS)|

Akerman, Jane; Wentzel, Donat G.

1973-01-01

237

AM CVn stars  

Microsoft Academic Search

I review our observational and theoretical knowledge of AM CVn stars,\\u000afocusing on recent developments. These include newly discovered systems, the\\u000apossibility that two recently discovered extremely short period objects are AM\\u000aCVn stars and an update on X-ray, UV an optical studies. Theoretical advances\\u000ainclude the study of the details of both the donor and accretor, and the\\u000aphysics

Gijs Nelemans

2004-01-01

238

The Bibliographical Star Index  

NASA Astrophysics Data System (ADS)

The Bibliographical Star Index (BSI) is a bibliographical survey of astrophysical papers on stars that were published in 12 journals from 1950 to 1972 or have been published in about 40 journals since 1972. Difficulties that prevented complete coverage of the stellar literature are discussed, along with limitations of and errors in the BSI. The contents of the BSI for the period from 1950 to 1978 are summarized, and the availability of the index is briefly noted.

Ochsenbein, F.

239

SSE: Single Star Evolution  

NASA Astrophysics Data System (ADS)

SSE is a rapid single-star evolution (SSE) code; these analytical formulae cover all phases of evolution from the zero-age main-sequence up to and including remnant phases. It is valid for masses in the range 0.1-100 Msun and metallicity can be varied. The SSE package contains a prescription for mass loss by stellar winds. It also follows the evolution of rotational angular momentum for the star.

Hurley, Jarrod R.; Pols, Onno R.; Tout, Christopher A.

2013-03-01

240

What Drives Star Formation?  

Microsoft Academic Search

Current theoretical models for what drives star formation (especially low-mass star formation) are: (1) magnetic support of self-gravitating clouds with ambipolar diffusion removing support in cores and triggering collapse, and (2) compressible turbulence forming self-gravitating clumps that collapse as soon as the turbulent cascade produces insufficient turbulent support. A crucial observational difference between the two models is the mass to

R. M. Crutcher

2003-01-01

241

Reaching for the STARs  

Microsoft Academic Search

\\u000a The prototype STAR (Signal Transduction and Activation of RNA) protein is Sam68, the Src-associated substrate during mitosis of 68 kDa. Sam68, like all other STAR proteins, belongs to the large class of heteronuclear ribonucleoprotein particle K (hnRNP\\u000a K) homology (KH) domain family of RNA-binding proteins. The KH domain is an evolutionarily conserved RNA binding domain that\\u000a consists of 70–100 amino

Stéphane Richard

242

Physics and Star Trek  

NSDL National Science Digital Library

Created and maintained by physicist Jason Hinson, the Physics and Star Trek Web site investigates faster than light travel and subspace physics. Each topic is presented as a mix of factual information along with speculation on the author's part on how these phenomena could or could not work. Although the site consists of much text and few graphics, which may turn away some potential readers, the interesting subject will definitely appeal to hard core Star Trek or physics junkies.

1999-01-01

243

Post-AGB Stars  

NASA Astrophysics Data System (ADS)

In this contribution, a review is presented on the ample data obtained on post-AGB stars, both on the central stars and their circumstellar material. The fast evolutionary phase is characterized by a rapid change in the properties of the objects, but the variety is so large that there is yet no clear consensus on how the detailed studies of individual objects are linked together by evolutionary channels. The absence of strong molecular veiling in the photospheres of the central stars, together with a spread in intrinsic metallicity make post-AGB stars very useful in constraining AGB chemical evolutionary models. We discuss the surprisingly wide variety of chemical signatures observed. The onset in the creation process of the panoply of structures and shapes observed in planetary nebulae occurs during the short post-AGB evolution, but the physical nature of the processes involved is still badly understood. In the rapidly growing field of circumstellar mineralogy, post-AGB stars have their story to tell and also the molecular envelope changes significantly due to dilution and hardening of the stellar radiation. The real-time evolution of some objects suffering a late thermal flash is reviewed and their possible link to other hydrogen-deficient objects is discussed. Any review on stellar evolution has a section on binaries and this contribution is no exception because binaries make up a significant fraction of the post-AGB stars known to date.

van Winckel, Hans

244

The Star*s Family - an Update  

NASA Astrophysics Data System (ADS)

We shall present the current situation of the Star*s Family, a growing collection of products: directories, dictionaries, databases, data sets, and so on. The directories gather together all practical data available on organizations involved in astronomy, space sciences and related fields, while the dictionaries concern abbreviations, acronyms, contractions and symbols encountered in the same fields. The databases correspond both to the dictionaries and directories. They are currently accessible on line at the European Southern Observatory (ESO) through Starcat and at the European Space Agency (ESA) through ESIS. Their implementation is presently carried out at Strasbourg astronomical Data Center (CDS). Other agreements are currently being negociated. Practical information on the availability of all products can be obtained from the author (telefax: +33-88491255).

Heck, Andre

1993-05-01

245

A fast star image extraction algorithm for autonomous star sensors  

NASA Astrophysics Data System (ADS)

Star sensors have been developed to acquire accurate orientation information in recent decades superior to other attitude measuring instruments. A star camera takes photos of the night sky to obtain star maps. An important step to acquire attitude knowledge is to compare the features of the observed stars in the maps with those of the cataloged stars using star identification algorithms. To calculate centroids of the star images before this step, they are required to be extracted from the star maps in advance. However, some large or ultra large imaging detectors are applied to acquire star maps for star sensors with the development of electronic imaging devices. Therefore, star image extraction occupies more and more portions of the whole attitude measurement period of time. It is required to shorten star image extraction time in order to achieve higher response rate. In this paper, a novel star image extraction algorithm is proposed which fulfill the tasks efficiently. By scanning star map, the pixels brighter than the gray threshold are found and their coordinates and brightness are stored in a cross-linked list. Data of these pixels are linked by pointers, while other pixels are neglected. Therefore, region growing algorithm can be used by choosing the first element in the list as a starting seed. New seeds are founded if the neighboring pixels are brighter than the threshold, and the last seed is deleted from the list. Next search continues until no neighboring pixels are in the list. At that time, one star image is extracted, and its centroid is calculated. Likely, other star images may be extracted, and then the examined seeds are deleted which are never considered again. A new star image search always begins from the first element for avoiding unnecessary scanning. The experiments have proved that for a 1024×1024 star map, the image extraction takes nearly 16 milliseconds. When CMOS APS is utilized to transfer image data, the real-time extraction can be almost achieved.

Zhu, Xifang; Wu, Feng; Xu, Qingquan

2012-11-01

246

Observing Iron Stars with Spitzer  

NASA Astrophysics Data System (ADS)

Only two so-called Iron stars exist: XX Oph and AS 325. XX Oph was first observed in 1924 by Merrill. He noted strong, doubly ionized iron emission lines were present in the spectra, thus the name iron star. AS325 was noted to be a similar type object by Howell and Bopp (1982). Further observations of both stars have led to the development of a model (Cool et al., 2005) for both stars which explains the optical emission lines and that the stars consist of two separate stars, possibly in a binary. The current model has each Iron Star composed of a Be star and a late type (supergiant) companion separated by 1-2 thousand AU. We plan to use Spitzer to observethe dust environment in the star AS325.

Thomas, Beth; Howell, Steve; Chapple, Lauren; Daou, Doris; Rapp, Steve; Roelofson, Theresa; Weehler, Cindy

2005-02-01

247

How star clusters could survive low star formation efficiencies  

NASA Astrophysics Data System (ADS)

After the stars of a new, embedded star cluster have formed they blow the remaining gas out of the cluster. Especially winds of high mass stars and definitely the on-set of the first super novae can remove the residual gas from a cluster. This leads to a very violent mass-loss and leaves the cluster out of virial equilibrium. Standard models predict that the star formation efficiency (SFE) has to be about 33 per cent for sudden (within one crossing-time of the cluster) gas expulsion to retain some of the stars in a bound cluster. If the efficiency is lower the stars of the cluster disperse completely. Recent observations reveal that in strong star bursts star clusters do not form in isolation but in complexes containing dozens and up to several hundred star clusters (super-clusters). By carrying out numerical experiments we demonstrate that in these environments (i.e. the deeper potential of the star cluster complex and the merging process of the star clusters within these super-clusters) the SFEs could be as low as 20 per cent, leaving a gravitationally bound stellar population. We demonstrate that the merging of the first clusters happens faster than the dissolution time therefore enabling more stars to stay bound within the merger object. Such an object resembles the outer Milky Way globular clusters and the faint fuzzy star clusters recently discovered in NGC 1023.

Fellhauer, Michael; Kroupa, Pavel

2004-12-01

248

Star Caught Smoking  

NASA Astrophysics Data System (ADS)

VLTI Snapshots Dusty Puff Around Variable Star Using ESO's Very Large Telescope Interferometer, astronomers from France and Brazil have detected a huge cloud of dust around a star. This observation is further evidence for the theory that such stellar puffs are the cause of the repeated extreme dimming of the star. ESO PR Photo 34a/07 ESO PR Photo 34a/07 Dust Cloud in a R CrB Star (Artist's Impression) R Coronae Borealis stars are supergiants exhibiting erratic variability. Named after the first star that showed such behaviour [1], they are more than 50 times larger than our Sun. R Coronae Borealis stars can see their apparent brightness unpredictably decline to a thousandth of their nominal value within a few weeks, with the return to normal light levels being much slower. It has been accepted for decades that such fading could be due to obscuration of the stellar surface by newly formed dusty clouds. This 'Dust Puff Theory' suggests that mass is lost from the R Coronae Borealis (or R CrB for short) star and then moves away until the temperature is low enough for carbon dust to form. If the newly formed dust cloud is located along our line-of-sight, it eclipses the star. As the dust is blown away by the star's strong light, the 'curtain' vanishes and the star reappears. RY Sagittarii is the brightest member in the southern hemisphere of this family of weird stars. Located about 6,000 light-years away towards the constellation of Sagittarius (The Archer), its peculiar nature was discovered in 1895 by famous Dutch astronomer Jacobus Cornelius Kapteyn. In 2004, near-infrared adaptive optics observations made with NACO on ESO's Very Large Telescope allowed astronomers Patrick de Laverny and Djamel Mékarnia to clearly detect the presence of clouds around RY Sagittarii. This was the first direct confirmation of the standard scenario explaining the light variations of R CrB stars by the presence of heterogeneities in their envelope surrounding the star. ESO PR Photo 32e/07 ESO PR Photo 34b/07 Clouds around RY Sagittarii (NACO/VLT) However, the precise place where such dust clouds would form was still unclear. The brightest cloud detected was several hundred stellar radii from the centre, but it had certainly formed much closer. But how much closer? To probe the vicinity of the star, the astronomers then turned to ESO's Very Large Telescope Interferometer. Combining two different pairs of the 8.2-m Unit Telescopes and using the mid-infrared MIDI instrument that allows detecting cold structures, the astronomers explored the inner 110 astronomical units [2] around the star. Given the remoteness of RY Sagittarii, this corresponds to looking at details on a one-euro coin that is about 75 km away! The astronomers found that a huge envelope, about 120 times as big as RY Sagittarii itself, surrounds the supergiant star. But more importantly, the astronomers also found evidence for a dusty cloud lying only about 30 astronomical units away from the star, or 100 times the radius of the star. "This is the closest dusty cloud ever detected around a R CrB-type variable since our first direct detection in 2004," says Patrick de Laverny, leader of the team. "However, it is still detected too far away from the star to distinguish between the different scenarios proposed within the Dust Puff Theory for the possible locations in which the dusty clouds form." If the cloud moves at the speed of 300 km/s, as one can conservatively assume, it was probably ejected more than 6 months before its discovery from deeper inside the envelope. The astronomers are now planning to monitor RY Sagittarii more carefully to shed more light on the evolution of the dusty clouds surrounding it. "Two hundred years after the discovery of the variable nature of R CrB, many aspects of the R CrB phenomenon remain mysterious," concludes de Laverny.

2007-08-01

249

The Double Star mission  

NASA Astrophysics Data System (ADS)

The Double Star Project DSP is the first major collaboration between Europe and China on a scientific space mission It comprises two spacecraft launched in December 2003 and July 2004 to study the Earth s magnetosphere in close coordination with ESA s Cluster mission The two Double Star orbits were explicitly designed to facilitate simultaneous observations when Double Star and Cluster are in separate but related regions e g Double Star 1 can observe in the reconnection region on the dayside of the magnetosphere while Cluster observes in the so-called cusp region where it can detect plasma flowing deep into the Earth s magnetosphere after entering the magnetosphere in the reconnection region By exploiting such measurements scientists are improving their understanding of the global magnetosphere much better than from either mission alone This talk will outline the key features of Double Star and its coordination with other activities It will show how this small science mission has complemented existing investments and thereby increased the overall scientific return

Hapgood, M.

250

Fingerprinting Nearby Star Suspects  

NASA Astrophysics Data System (ADS)

To identify and characterize the Sun's neighbors, we propose to obtain red spectra (5300-9900+ Å) for suspected nearby red, brown, and white dwarfs. These spectra play an important role in a new parallax effort initiated as part of a small telescope consortium operating at CTIO. This new effort, CTIOPI2, will be an expansion of the highly successful CTIOPI effort - an NOAO Surveys Program in which we are measuring parallaxes for more than 200 southern nearby stars. Both are carried out under the RECONS (Research Consortium on Nearby Stars) effort based at Georgia State U., Johns Hopkins U., and U. Virginia. During RECONS' two previous CTIO spectroscopic observing runs, we had two partly cloudy nights in Feb 1998, and three rainy nights in Jul 2001. Nonetheless, from the earlier run's meager data we have identified six new stars within 25 pc, two of which lie within 10 pc. High quality spectra for these new nearby stars are being provided to the fundamental database of the NASA/NSF NStars Project. This proposal is similar to our previous proposal, 2001A-0270, although we now include three new samples of stars that are being examined for CTIOPI2 targets. These samples are being used for both PhD (Jao, Subasavage) and undergraduate senior (Bean, Walkowicz) theses.

Henry, Todd J.; Bean, Jacob; Golimowski, Dave; Jao, Wei-Chun; Subasavage, John; Walkowicz, Lucianne

2002-02-01

251

Blurred Star Image Processing for Star Sensors under Dynamic Conditions  

PubMed Central

The precision of star point location is significant to identify the star map and to acquire the aircraft attitude for star sensors. Under dynamic conditions, star images are not only corrupted by various noises, but also blurred due to the angular rate of the star sensor. According to different angular rates under dynamic conditions, a novel method is proposed in this article, which includes a denoising method based on adaptive wavelet threshold and a restoration method based on the large angular rate. The adaptive threshold is adopted for denoising the star image when the angular rate is in the dynamic range. Then, the mathematical model of motion blur is deduced so as to restore the blurred star map due to large angular rate. Simulation results validate the effectiveness of the proposed method, which is suitable for blurred star image processing and practical for attitude determination of satellites under dynamic conditions.

Zhang, Weina; Quan, Wei; Guo, Lei

2012-01-01

252

Blurred star image processing for star sensors under dynamic conditions.  

PubMed

The precision of star point location is significant to identify the star map and to acquire the aircraft attitude for star sensors. Under dynamic conditions, star images are not only corrupted by various noises, but also blurred due to the angular rate of the star sensor. According to different angular rates under dynamic conditions, a novel method is proposed in this article, which includes a denoising method based on adaptive wavelet threshold and a restoration method based on the large angular rate. The adaptive threshold is adopted for denoising the star image when the angular rate is in the dynamic range. Then, the mathematical model of motion blur is deduced so as to restore the blurred star map due to large angular rate. Simulation results validate the effectiveness of the proposed method, which is suitable for blurred star image processing and practical for attitude determination of satellites under dynamic conditions. PMID:22778666

Zhang, Weina; Quan, Wei; Guo, Lei

2012-05-22

253

General Relativity&Compact Stars  

SciTech Connect

Compact stars--broadly grouped as neutron stars and white dwarfs--are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of tens to thousands of millions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms--hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star, ashes and all, falls at the end of the luminous phase. Neutron stars are the smallest, densest stars known. Like all stars, neutron stars rotate--some as many as a few hundred times a second. A star rotating at such a rate will experience an enormous centrifugal force that must be balanced by gravity or else it will be ripped apart. The balance of the two forces informs us of the lower limit on the stellar density. Neutron stars are 10{sup 14} times denser than Earth. Some neutron stars are in binary orbit with a companion. Application of orbital mechanics allows an assessment of masses in some cases. The mass of a neutron star is typically 1.5 solar masses. They can therefore infer their radii: about ten kilometers. Into such a small object, the entire mass of our sun and more, is compressed.

Glendenning, Norman K.

2005-08-16

254

Electrophotometry of variable stars  

NASA Astrophysics Data System (ADS)

Sample observations of eclipsing variables made in Berlin, Germany, using a 25-cm Schmidt-Cassegrain telescope and an electric photometer with an EMI 9781B tube and UBV filters are presented, with the aim of demonstrating the usefulness and attainable precision of amateur observations of these stars. The photometer calibration procedure is outlined, and light curves of XY Leo, WW CnC, SAO 072799, BM Cas, V695 Gyg, Zeta And, RX Cas, and the 'c' object in Lynx (discovered by Frank in January, 1983) are discussed. The latter is found in preliminary observations to have a period of 0.197 day (assuming it is an eclipsing binary), and the fact that its B minimum occurs about 4 min later than its V minimum suggests that it may be a Delta-Scuti-type binary containing an A star. It is pointed out that a large number of unmeasured variable stars are of sufficient brightness for amateur photometric observations.

Fernandes, M.

1983-09-01

255

BSE: Binary Star Evolution  

NASA Astrophysics Data System (ADS)

BSE is a rapid binary star evolution code. It can model circularization of eccentric orbits and synchronization of stellar rotation with the orbital motion owing to tidal interaction in detail. Angular momentum loss mechanisms, such as gravitational radiation and magnetic braking, are also modelled. Wind accretion, where the secondary may accrete some of the material lost from the primary in a wind, is allowed with the necessary adjustments made to the orbital parameters in the event of any mass variations. Mass transfer occurs if either star fills its Roche lobe and may proceed on a nuclear, thermal or dynamical time-scale. In the latter regime, the radius of the primary increases in response to mass-loss at a faster rate than the Roche-lobe of the star. Prescriptions to determine the type and rate of mass transfer, the response of the secondary to accretion and the outcome of any merger events are in place in BSE.

Hurley, Jarrod R.; Tout, Christopher A.; Pols, Onno R.

2013-03-01

256

Energy Production in Stars  

NSDL National Science Digital Library

Energy Production in Stars is part of the Astronomy 162: Stars, Galaxies, and Cosmology course offered by the Department of Physics and Astronomy at the University of Tennessee. This section covers the mass-energy relation of special relativity; the curve of binding energy, and its implications for fusion and fission reactions, and stellar energy production; nuclear reactions, and their relation to the Coulomb barrier, and quantum mechanical tunneling; temperature and pressure in stars, including the kinetic theory of gases, ideal gas law, and the Gamow window for charged particle reactions; the proton-proton chain; the carbon-nitrogen-oxygen (CNO) cycle; the triple-alpha process, mass-5 and mass-8 bottlenecks; advanced burning stages; stellar energy transport; and the solar neutrino problem.

2007-04-13

257

Stars in the braneworld  

NASA Astrophysics Data System (ADS)

We show that, in a Randall-Sundrum II type braneworld, the vacuum exterior of a spherical star is not in general a Schwarzschild spacetime, but has radiative-type stresses induced by five-dimensional graviton effects. Standard matching conditions do not lead to a unique exterior on the brane because of these five-dimensional graviton effects. We find an exact uniform-density stellar solution on the brane, and show that the general relativity upper bound GM/R<49 is reduced by five-dimensional high-energy effects. The existence of neutron stars leads to a constraint on the brane tension that is stronger than the big bang nucleosynthesis constraint, but weaker than the Newton-law experimental constraint. We present two different non-Schwarzschild exteriors that match the uniform-density star on the brane, and we give a uniqueness conjecture for the full five-dimensional problem.

Germani, Cristiano; Maartens, Roy

2001-12-01

258

Double Neutron Star Systems and Natal Neutron Star Kicks  

Microsoft Academic Search

We study the four double neutron star systems found in the Galactic disk in terms of the orbital characteristics of their immediate progenitors and the natal kicks imparted to neutron stars. Analysis of the effect of the second supernova explosion on the orbital dynamics, combined with recent results from simulations of rapid accretion onto neutron stars, lead us to conclude

Chris Fryer; Vassiliki Kalogera

1997-01-01

259

Computational astrophysics: Pulsating stars  

NASA Astrophysics Data System (ADS)

The field of computational astrophysics in pulsating star studies has grown considerably since the advent of the computer. Initially calculations were done on the IBM 704 with 32K of memory and now we use the CRAY YMP computers with considerably more memory. Our early studies were for models of pulsating stars using a 1D Lagrangian hydrodynamic code (SPEC) with radiation diffusion. The radiative transfer was treated in the equilibrium diffusion approximation and the hydrodynamics was done utilizing the approximation of artificial viscosity. The early calculations took many hours of 704 CPU time. Early in 1965 we decided to improve on the usual treatment of the radiative transfer used in our codes by utilizing the method of moments, the so-called variable Eddington approximation. In this approximation the material energy field is uncoupled from the radiation energy field and the angular dependence is introduced through the Eddington factor. A multigroup frequency dependent method may also be applied. The Eddington factor is determined by snapshots of the stars structure utilizing a y-line approximation. The full radiative transfer approximation appears necessary in order to understand the light curves for W Virginia stars and may be important for the light curves of RR Lyrae stars. A detailed radiative transfer method does not appear to be necessary for the understanding of Cepheid light curves. A recent improvement to our models for pulsating stars is in the use of an adaptive mesh scheme to resolve the sharp features in the nonlinear hydrodynamic structure. From these improved structures, better analysis of the radius, velocity, and light curves could be obtained.

Davis, C. G.

260

High mass stars: starbursts  

NASA Astrophysics Data System (ADS)

Starbursts are the preferred place where massive stars form; the main source of thermal and mechanical heating in the interstellar medium, and the factory where the heavy elements form. Thus, starbursts play an important role in the origin and evolution of galaxies. Starbursts are bright at ultraviolet (UV) wavelengths, and after the pioneering IUE program, high spatial and spectral resolution UV observations of local starburst galaxies, mainly taken with HST and FUSE, have made relevant contributions to the following issues: a) The determination of the initial mass function in violent star forming systems in low and high metallicity environments, and in dense (e.g. in stellar clusters) and diffuse environments. b) The modes of star formation: Starburst clusters are an important mode of star formation. c) The role of starbursts in AGN. d) The interaction between massive stars and the interstellar and intergalactic media. e) The contribution of starbursts to the reionization of the universe. Despite the very significant progress obtained over the past two decades of UV observations of starbursts, there are important problems that still need to be solved. High-spatial resolution UV observations of nearby starbursts are crucial to further progress in understanding the violent star formation processes in galaxies, the interaction between the stellar clusters and the interstellar medium, and the variation of the IMF. Thus, a new UV mission furnished with an intermediate spectral resolution long-slit spectrograph with high spatial resolution and high UV sensitivity is required to further progress in the study of starburst galaxies and their impact on the evolution of galaxies.

González Delgado, R. M.

2006-08-01

261

Morphodynamics of star dunes  

NASA Astrophysics Data System (ADS)

Star dunes are among the biggest and the most impressive dunes in Earth sand seas. Nonetheless, they remain poorly studied, probably because of their apparent complexity. They are massive pyramidal dunes with interlaced arms whose slip faces are oriented in various directions. Being large, they can integrate wind properties over a wide range of time scales. Thus, they are observed for wind regimes with multiple directions, and may result from the amalgamation of dunes or from the development of arms on a well-established dune pattern. In both cases, the roles of wind directional variability and secondary flow have been emphasized but not precisely quantified. Here, we report simulations where the star dune shape results from a a combination of longitudinal dunes, which form the star dune arms. These arms may radiate and so interact with the other dunes in the field. This mass exchange, controlled by the morphodynamics of star dunes arms, must play an important role in the large-scale arrangement of star dunes networks. We first demonstrate that star dune arms orientation maximizes the flux in the direction of crests. This is opposed to the usually admit dunes orientation, which maximizes the sediment transport perpendicular to the crest. Indeed, depending on sand availability, dunes development results from the growth of a wave on a sand bed or from a net transport of sediment, which grows and extends an isolated longitudinal dune over a non-erodible soil. These two different mechanisms lead to two different modes of crests orientation. Then, we show that the propagating arms reach a stationary state characterized by constant width, height and growth rate. These are controlled by the frequency at which the wind changes direction. Arm width and height increase, whereas the propagation speed decreases with a decreasing frequency. These morphodynamics properties are helpful to assess from pattern observation the variability of wind directionality over several time scales.

Zhang, D.; Narteau, C.; Rozier, O.; Courrech du Pont, S.

2012-04-01

262

American Urban Star Fest  

NASA Astrophysics Data System (ADS)

Over the last couple of decades New York City implemented, and continues to carry out, several schemes of eradicating luminous graffiti. One result has been the gradual recovery of the natural night sky. By 1994 the normal clear sky transparency over Manhattan deepened to fourth magnitude and has been slowly creeping deeper, until in 2002 it is at magnitude 4 to 4.5. In the spring of 1995, during some lazing on a Manhattan rooftop under a sky full of stars, several New York astronomers hatched the idea of letting the whole people celebrate the renewed starry sky. In due course they, through the Amateur Astronomers Association, engaged the New York City Parks Department and the Urban Park Rangers in an evening of quiet picnicking to enjoy the stars in their natural sky. Thus the Urban Star Fest was born. The event thrilled about 3,000 visitors in Central Park's Sheep Meadow on Saturday 30 September 1995. This year's Fest, the eighth in the series demonstrated the City's upper skyline of stars on Saturday 5 October 2002 to about 2,200 enthused visitors. Although the Fest is always noted as cancelable for inclement weather, so far, it has convened every year, with attendance ranging from 4,000 down to a mere 1,000, this latter being under the smoke plume of the World Trade Center in 2001. Despite this swing in attendance, the American Urban Star Fest is America's largest regularly scheduled public astronomy event. Of course, special occasions, like comets or eclipses, can and do attract far larger interest both in the city and elsewhere. The presentation shows the setup and program of the American Urban Star Fest, to illustrate how the general public can actively become aware of the night sky and see for themselves the result of their very own efforts at removing light pollution--and note where improvement is yet to come.

Pazmino, John

2003-12-01

263

Star Formation in Irregular Galaxies.  

ERIC Educational Resources Information Center

|Examines mechanisms of how stars are formed in irregular galaxies. Formation in giant irregular galaxies, formation in dwarf irregular galaxies, and comparisons with larger star-forming regions found in spiral galaxies are considered separately. (JN)|

Hunter, Deidre; Wolff, Sidney

1985-01-01

264

The Death of a Star  

ERIC Educational Resources Information Center

|Theories associated with the gravitational collapse of a star into black holes" are described. Suggests that the collapse and compression might go through the stages from white dwarf star to neutron core to black hole." (TS)|

Thorne, Kip S.

1971-01-01

265

THE SOLAR NEIGHBORHOOD. XXVI. AP Col: THE CLOSEST (8.4 pc) PRE-MAIN-SEQUENCE STAR  

SciTech Connect

We present the results of a multi-technique investigation of the M4.5Ve flare star AP Col, which we discover to be the nearest pre-main-sequence star. These include astrometric data from the CTIO 0.9 m, from which we derive a proper motion of 342.0 {+-} 0.5 mas yr{sup -1}, a trigonometric parallax of 119.21 {+-} 0.98 mas (8.39 {+-} 0.07 pc), and photometry and photometric variability at optical wavelengths. We also provide spectroscopic data, including radial velocity (22.4 {+-} 0.3 km s{sup -1}), lithium equivalent width (EW) (0.28 {+-} 0.02 A), H{alpha} EW (-6.0 to -35 A), vsin i (11 {+-} 1 km s{sup -1}), and gravity indicators from the Siding Spring 2.3 m WiFeS, Lick 3 m Hamilton echelle, and Keck-I HIRES echelle spectrographs. The combined observations demonstrate that AP Col is the closer of only two known systems within 10 pc of the Sun younger than 100 Myr. Given its space motion and apparent age of 12-50 Myr, AP Col is likely a member of the recently proposed {approx}40 Myr old Argus/IC 2391 Association.

Riedel, Adric R.; Henry, Todd J.; Jao, Wei-Chun [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302-4106 (United States); Murphy, Simon J. [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Melis, Carl [Center for Astrophysics and Space Sciences, University of California, San Diego, CA 92093-0424 (United States); Subasavage, John P., E-mail: riedel@chara.gsu.edu, E-mail: thenry@chara.gsu.edu, E-mail: jao@chara.gsu.edu, E-mail: murphysj@mso.anu.edu.au, E-mail: cmelis@ucsd.edu, E-mail: jsubasavage@ctio.noao.edu [Cerro Tololo Inter-American Observatory, La Serena (Chile)

2011-10-15

266

Stability of relativistic stars  

NASA Astrophysics Data System (ADS)

Stable relativistic stars form a two-parameter family, parametrized by mass and angular velocity. Limits on each of these quantities are associated with relativistic instabilities discovered by Chandrasekhar: A radial instability, to gravitational collapse or explosion, marks the upper and lower limits on their mass; and an instability driven by gravitational waves may set an upper limit on their spin. Our summary of relativistic stability theory given here is based on and includes excerpts from the book Rotating Relativistic Stars, by the present authors (Friedman & Sterigioulas 2011).

Friedman, John L.; Stergioulas, Nikolaos

2011-03-01

267

Ten Famous Double Stars  

NASA Astrophysics Data System (ADS)

In this chapter we move out from the Sun and look at some of the neighbouring double and multiple stars which have been observed for centuries. In some cases there are still secrets to be revealed. The beauty of a sunset on Earth has inspired poets and artists for millennia—what must it be like when there is not one sunset but two or more with each sun glowing in a different color. The chiaroscuro would be impressive to say the least. Not all double and multiple systems have different colors—some contain stars of essentially the same spectral class and therefore color (Table 9.1).

Argyle, Bob; Argyle, R. W.

268

Star cluster dynamics.  

PubMed

Dynamical evolution plays a key role in shaping the current properties of star clusters and star cluster systems. A detailed understanding of the effects of evolutionary processes is essential to be able to disentangle the properties that result from dynamical evolution from those imprinted at the time of cluster formation. In this review, I focus my attention on globular clusters, and review the main physical ingredients driving their early and long-term evolution, describe the possible evolutionary routes and show how cluster structure and stellar content are affected by dynamical evolution. PMID:20083508

Vesperini, Enrico

2010-02-28

269

Isolating Triggered Star Formation  

SciTech Connect

Galaxy pairs provide a potentially powerful means of studying triggered star formation from galaxy interactions. We use a large cosmological N-body simulation coupled with a well-tested semi-analytic substructure model to demonstrate that the majority of galaxies in close pairs reside within cluster or group-size halos and therefore represent a biased population, poorly suited for direct comparison to 'field' galaxies. Thus, the frequent observation that some types of galaxies in pairs have redder colors than 'field' galaxies is primarily a selection effect. We use our simulations to devise a means to select galaxy pairs that are isolated in their dark matter halos with respect to other massive subhalos (N= 2 halos) and to select a control sample of isolated galaxies (N= 1 halos) for comparison. We then apply these selection criteria to a volume-limited subset of the 2dF Galaxy Redshift Survey with M{sub B,j} {le} -19 and obtain the first clean measure of the typical fraction of galaxies affected by triggered star formation and the average elevation in the star formation rate. We find that 24% (30.5 %) of these L* and sub-L* galaxies in isolated 50 (30) h{sup -1} kpc pairs exhibit star formation that is boosted by a factor of {approx}> 5 above their average past value, while only 10% of isolated galaxies in the control sample show this level of enhancement. Thus, 14% (20 %) of the galaxies in these close pairs show clear triggered star formation. Our orbit models suggest that 12% (16%) of 50 (30) h{sup -1} kpc close pairs that are isolated according to our definition have had a close ({le} 30 h{sup -1} kpc) pass within the last Gyr. Thus, the data are broadly consistent with a scenario in which most or all close passes of isolated pairs result in triggered star formation. The isolation criteria we develop provide a means to constrain star formation and feedback prescriptions in hydrodynamic simulations and a very general method of understanding the importance of triggered star formation in a cosmological context.

Barton, Elizabeth J.; Arnold, Jacob A.; /UC, Irvine; Zentner, Andrew R.; /KICP, Chicago /Chicago U., EFI; Bullock, James S.; /UC, Irvine; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC

2007-09-12

270

Tech Stars Scholarship Program  

NSDL National Science Digital Library

Seek grant funding for scholarships that target engineering technology. Unique scholarships and associated benefits will help differentiate your program from others. The Tech Stars program at Florence-Darlington Technical College is a successful example of this strategy. The loan-to-own laptop computer feature of this scholarship program is resulting in higher enrollments and more full-time students in the target majors. Tech Star students must agree to certain guidelines to receive the laptop or awards used for books, tuition or computer technology certification fees.

2009-07-15

271

Synthetic guide star generation  

DOEpatents

A system for assisting in observing a celestial object and providing synthetic guide star generation. A lasing system provides radiation at a frequency at or near 938 nm and radiation at a frequency at or near 1583 nm. The lasing system includes a fiber laser operating between 880 nm and 960 nm and a fiber laser operating between 1524 nm and 1650 nm. A frequency-conversion system mixes the radiation and generates light at a frequency at or near 589 nm. A system directs the light at a frequency at or near 589 nm toward the celestial object and provides synthetic guide star generation.

Payne, Stephen A. (Castro Valley, CA); Page, Ralph H. (Castro Valley, CA); Ebbers, Christopher A. (Livermore, CA); Beach, Raymond J. (Livermore, CA)

2008-06-10

272

Global Star-Formation Rates  

Microsoft Academic Search

I review the basic modes of quiescent star formation and starbursts. Star-formation efficiency is the key to reconciling hierarchical\\u000a galaxy formation with observed galaxy colours and counts. A unified viewpoint is that all star formation is, at some level,\\u000a bursty. This is motivated both by local observations and by theory. I describe how self-regulation of star formation provides\\u000a prescriptions for

Joseph Silk

2005-01-01

273

Star formation and the Galaxy  

Microsoft Academic Search

This review discusses the extent of star formation in the Milky Way with emphasis on the role of large-scale phenomena. Consideration is given to the problems of star formation in the disk in the particular context of density-wave shock theory. Some tests of the relationships between the density-wave shock and star formation, the rate of star formation, the role of

F. J. Kerr

1977-01-01

274

External triggers of star formation  

Microsoft Academic Search

The local processes leading to star-formation are not well known; gravitational instabilities can be triggered by shocks and stellar winds, and it is believed that star-formation can thus propagate. Cloud-cloud collisions have been assumed to trigger star-formation or at least giant molecular clouds formation. On the kpc scale, the star-formation rate seems to be proportional to some power of the

F. Combes

1993-01-01

275

The Wolf-Rayet stars  

Microsoft Academic Search

The characteristics of Wolf-Rayet stars and stars with properties similar to the Wolf-Rayet stars are discussed. The observational features of Wolf-Rayet stars, which were originally distinguished as objects with very broad spectral emissions, are presented with attention given to spectra in the photographic region, spectral classification, spectral correlations, near-infrared and ultraviolet observations, elements present, line profiles, spatial distribution, absolute magnitudes,

J. Sahade

1980-01-01

276

Star Formation Through Cosmic Time  

Microsoft Academic Search

I will review the literature on the star formation history of the Universe, from the first stars up to the current day. The first (population III) stars appear to be responsible for the re-ionization of the Universe, and for seeding the inter-galactic medium with heavy elements, facilitating the formation of subsequent generations. There are now many lines of evidence from

Michael A. Dopita

2007-01-01

277

Initial Conditions for Star Formation  

Microsoft Academic Search

Recent studies have provided important information on the initial conditions for the formation of low mass stars. These studies, using submillimeter continuum and line observations, have identified objects in the earliest stages of star formation as cold, dense cores in which most molecules are frozen onto dust grains. We are placing constraints on different theories of star formation with these

N. J. Evans

2002-01-01

278

Star Formation in Spiral Arms  

Microsoft Academic Search

The origin and types of spiral arms are reviewed with an emphasis on the connections between these arms and star formation. Flocculent spiral arms are most likely the result of transient instabilities in the gas that promote dense cloud formation, star formation, and generate turbulence. Long irregular spiral arms are usually initiated by gravitational instabilities in the stars, with the

B. G. Elmegreen

2011-01-01

279

The Life of a Star  

NSDL National Science Digital Library

This website provides an introduction to what a star is and the evolution of high and low mass stars. It details the life of a star that is one solar mass and over ten solar masses. Pictures, graphs, and links are also provided for the user within the site.

2004-12-18

280

A Vanishing Star Revisited  

NASA Astrophysics Data System (ADS)

VLT Observations of an Unusual Stellar System Reinhold Häfner of the Munich University Observatory (Germany) is a happy astronomer. In 1988, when he was working at a telescope at the ESO La Silla observatory, he came across a strange star that suddenly vanished off the computer screen. He had to wait for more than a decade to get the full explanation of this unusual event. On June 10-11, 1999, he observed the same star with the first VLT 8.2-m Unit Telescope (ANTU) and the FORS1 astronomical instrument at Paranal [1]. With the vast power of this new research facility, he was now able to determine the physical properties of a very strange stellar system in which two planet-size stars orbit each other. One is an exceedingly hot white dwarf star , weighing half as much as the Sun, but only twice as big as the Earth. The other is a much cooler and less massive red dwarf star , one-and-a-half times the size of planet Jupiter. Once every three hours, the hot star disappears behind the other, as seen from the Earth. For a few minutes, the brightness of the system drops by a factor of more than 250 and it "vanishes" from view in telescopes smaller than the VLT. A variable star named NN Serpentis ESO PR Photo 30a/99 ESO PR Photo 30a/99 [Preview - JPEG: 400 x 468 pix - 152k] [Normal - JPEG: 800 x 936 pix - 576k] [High-Res - JPEG: 2304 x 2695 pix - 4.4M] Caption to ESO PR Photo 30a/99 : The sky field around the 17-mag variable stellar system NN Serpentis , as seen in a 5 sec exposure through a V(isual) filter with VLT ANTU and FORS1. It was obtained just before the observation of an eclipse of this unsual object and served to centre the telescope on the corresponding sky position. The field shown here measures 4.5 x 4.5 armin 2 (1365 x 1365 pix 2 ; 0.20 arcsec/pix). The field is somewhat larger than that shown in Photo 30b/99 and has the same orientation to allow comparison: North is about 20° anticlockwise from the top and East is 90° clockwise from that direction. The unsual star in question is designated NN Serpentis , or just NN Ser . As the name indicates, it is located in the constellation of Serpens (The Serpent), about 12° north of the celestial equator. A double letter, here "NN", is used to denote variable stars [2]. It is a rather faint object of magnitude 17, about 25,000 times fainter than what can be perceived with the unaided eye. The distance is about 600 light-years (180 pc). In July 1988, Reinhold Häfner performed observations of NN Ser (at that time still known by its earlier name PG 1550+131 ) with the Danish 1.54-m telescope at La Silla. He was surprised, but also very pleased to discover that it underwent a very deep eclipse every 187 minutes. Within less than 2 minutes, the brightness dropped by a factor of more than 100 (5 magnitudes). During the next 9 minutes, the star completely disappeared from view - it was too faint to be observed with this telescope. It then again reappeared and the entire event was over after just 11 minutes. Why eclipses are so important for stellar studies An eclipse occurs when one of the stars in a binary stellar system moves in front of the other, as seen by the observer. The effect is similar to what happens during a solar eclipse when the Moon moves in front of the Sun. In both cases, the eclipse may be partial or total , depending on whether or not the eclipsed star (or the Sun) is completely hidden from view. The occurence of eclipses in stellar systems, as seen from the Earth, depends on the spatial orientation of the orbital plane and the sizes of the two stars. Two eclipses take place during one orbital revolution, but they may not both be observable. The physical properties of the two stars in a binary system (e.g., the sizes of the stars, the size and shape of the orbit, the distribution of the light on the surfaces of the stars, their temperatures etc.) can be determined from the measured "light-curve" of the system (a plot of brightness vrs. time). The stars are always too close to each other to be seen as anything but a point of lig

1999-07-01

281

Infrared Stars. The Interaction between Stars and Interstellar Clouds Produces 'Infrared Stars' of Two Different Kinds.  

National Technical Information Service (NTIS)

Searches for very cool stars have revealed three kinds of objects: very cool Mira stars, perhaps cooler than any of this type previously known; extremely dense interstellar clouds, more dense than any known heretofore; and probably, cool circumstellar clo...

H. L. Johnson

1967-01-01

282

Superbursts from Strange Stars  

NASA Astrophysics Data System (ADS)

Recent models of carbon ignition on accreting neutron stars predict superburst ignition depths that are an order of magnitude larger than those observed. We explore a possible solution to this problem, that the compact stars in low-mass X-ray binaries that have shown superbursts are in fact strange stars with a crust of normal matter. We calculate the properties of superbursts on strange stars and the resulting constraints on the properties of strange quark matter. We show that the observed ignition conditions exclude fast neutrino emission in the quark core, for example, by the direct Urca process, which implies that strange quark matter at stellar densities should be in a color superconducting state. For slow neutrino emission in the quark matter core, we find that reproducing superburst properties requires a definite relation between three poorly constrained properties of strange quark matter: its thermal conductivity (K), its slow neutrino emissivity (??~=Q?T89), and the energy released by converting a nucleon into strange quark matter (QSQM).

Page, Dany; Cumming, Andrew

2005-12-01

283

The North (Wall) Star  

NSDL National Science Digital Library

Celestial navigation is the art and science of finding one's geographic position by means of astronomical observations, particularly by measuring altitudes of celestial objects â sun, moon, planets or stars. This activity starts with a basic, but very important and useful, celestial measurement.

Integrated Teaching And Learning Program

284

Reaching for the Stars.  

ERIC Educational Resources Information Center

|Describes "Reaching for the Stars," a program which develops teaming and mentoring skills in senior physics students. Phase 1 requires student pairs to design a rocket; Phase 2 pairs seniors with gifted second graders who build the rocket from written instructions; and in Phase 3, pairs of seniors create a children's storybook explaining one of…

Roper-Davis, Sharon

1999-01-01

285

Physics of the Stars  

ERIC Educational Resources Information Center

|Describes how astrophysics can be a do-it-yourself project within a school boy's budget and background, by giving detailed instruction on equipment construction. In addition, this article describes many experiments to undertake, with the equipment, such as determining color temperature, star spectra, chemical composition and others. (BR)|

Haig, G. Y.

1974-01-01

286

SI Traceable Stars  

NASA Astrophysics Data System (ADS)

Astronomy, satellite, and defense programs require accurate SI traceable standards in space for calibrating telescope-based sensors, assessing their accuracy, and ensuring that their measurements can be compared with other sensors. For satellites, including space-based telescopes, the lack of such standards makes it difficult to ensure that the pre-launch calibration is maintained following exposure of the sensor to launch vibration, high-energy radiation, and out-gassed vapor condensation. Stars have been used for calibration; however star catalogs show discrepancies from 2~% to 5~%, even though approximately 50~% of stars have photometric stabilities greater than 0.5~%. Historically, absolute stellar calibration has been challenged by the lack of available optical standards that closely mimic stellar spectral and angular distributions, of measurement methods to use such standards, and of knowledge of the temporally variable transmittance of the atmosphere. In this talk, we will address these deficiencies with the goal of establishing a suite of SI traceable stars for optical sensor calibration with a radiometric uncertainty of 0.5~% over the spectral range from 380~nm to 2500~nm.

Yoon, H. W.; Lykke, K. R.; Brown, S. W.; Johnson, B. C.; Fraser, G. T.

2007-12-01

287

Rotating Relativistic Stars  

NASA Astrophysics Data System (ADS)

1. Stationary, axisymmetric equilibria; 2. 3+1 split, action, Lagrangian and Hamiltonian formalisms; 3. Asymptotics, virial identities and nonaxisymmetric equilibria; 4. Numerical schemes; 5. Equilibrium models; 6. Approximation methods; 7. Perturbation theory of relativistic fluids; 8. Quasinormal modes; 9. Stellar stability; 10. Nonlinear dynamics of rotating relativistic stars; Appendix.

Friedman, John L.; Stergioulas, Nikolaos

2013-04-01

288

Magnetic Dynamos and Stars  

SciTech Connect

Djehuty is a code that has been developed over the last five years by the Lawrence Livermore National Laboratory (LLNL), from earlier code designed for programmatic efforts. Operating in a massively parallel environment, Djehuty is able to model entire stars in 3D. The object of this proposal was to continue the effort to introduce magneto-hydrodynamics (MHD) into Djehuty, and investigate new classes of inherently 3D problems involving the structure, evolution and interaction of stars and planets. However, towards the end of the second year we discovered an unexpected physical process of great importance in the evolution of stars. Consequently for the third year we changed direction and concentrated on this process rather than on magnetic fields. Our new process was discovered while testing the code on red-giant stars, at the 'helium flash'. We found that a thin layer was regularly formed which contained a molecular-weight inversion, and which led therefore to Rayleigh-Taylor instability. This in turn led to some deeper-than-expected mixing, which has the property that (a) much {sup 3}He is consumed, and (b) some {sup 13}C is produced. These two properties are closely in accord with what has been observed over the last thirty years in red giants, whereas what was observed was largely in contradiction to what earlier theoretical models predicted. Thus our new 3D models with Djehuty explain a previously-unexplained problem of some thirty years standing.

Eggleton, P P

2007-02-15

289

Reaching for the Stars  

ERIC Educational Resources Information Center

|Dr. Mae Jemison is the world's first woman astronaut of color who continues to reach for the stars. Jemison was recently successful in leading a team that has secured a $500,000 federal grant to make interstellar space travel a reality. The Dorothy Jemison Foundation for Excellence (named after Jemison's mother) was selected in June by the…

Terry, Dorothy Givens

2012-01-01

290

The Double Star mission  

Microsoft Academic Search

The Double Star Programme (DSP) was first proposed by China in March, 1997 at the Fragrant Hill Workshop on Space Science, Beijing, organized by the Chinese Academy of Science. It is the first mission in collaboration between China and ESA. The mission is made of two spacecraft to investigate the magnetospheric global processes and their response to the interplanetary disturbances

Z. X. Liu; C. P. Escoubet; Z. Pu; H. Laakso; J. K. Shi; C. Shen; M. Hapgood

2005-01-01

291

Trek to the Stars  

ERIC Educational Resources Information Center

|"Star Trek", which was aired on television for three years, brought the creatures and conflicts of the "outer reaches" of space into our living rooms. Here its new episodes and reruns are analyzed by elementary students as part of a social studies/elementary science curriculum. (Author/RK)|

Rubinstein, Robert E.

1977-01-01

292

Physics of the Stars  

ERIC Educational Resources Information Center

Describes how astrophysics can be a do-it-yourself project within a school boy's budget and background, by giving detailed instruction on equipment construction. In addition, this article describes many experiments to undertake, with the equipment, such as determining color temperature, star spectra, chemical composition and others. (BR)

Haig, G. Y.

1974-01-01

293

Division Iv: Stars  

NASA Astrophysics Data System (ADS)

This Division IV was started on a trial basis at the General Assembly in The Hague 1994 and was formally accepted at the Kyoto General Assembly in 1997. Its broad coverage of ``Stars'' is reflected in its relatively large number of Commissions and so of members (1266 in late 2011). Its kindred Division V, ``Variable Stars'', has the same history of its beginning. The thinking at the time was to achieve some kind of balance between the number of members in each of the 12 Divisions. Amid the current discussion of reorganizing the number of Divisions into a more compact form it seems advisable to make this numerical balance less of an issue than the rationalization of the scientific coverage of each Division, so providing more effective interaction within a particular field of astronomy. After all, every star is variable to a certain degree and such variability is becoming an ever more powerful tool to understand the characteristics of every kind of normal and peculiar star. So we may expect, after hearing the reactions of members, that in the restructuring a single Division will result from the current Divisions IV and V.

Corbally, Christopher; D'Antona, Francesca; Spite, Monique; Asplund, Martin; Charbonnel, Corinne; Docobo, Jose Angel; Gray, Richard O.; Piskunov, Nikolai E.

2012-04-01

294

The First Stars  

NSDL National Science Digital Library

The very first stars in the universe died a long time before astronomers could get a look at them. Billions of years after the last of these first stars expired, telescopes are finally tracking them down. This radio broadcast uncovers new research into how the transition from dark to light came about. After the Big Bang which established time, space and matter, there was a dark age - a stretch of 100 million years which persisted until the first lights appeared. The broadcast explains why the first stars - before the stars and galaxies we know today came into being - are believed to have been phenomenally large protostars with a mass - or weight - around 100 times greater than our own Sun and occupying a vastly greater volume of space. So far, no visual trace of these megastars has been found, but we could be on the threshold of finding it, perhaps with the NGST telescope (Next Generation Space Telescope). The broadcast is 30 minutes in length.

295

Emmy's Moon and Stars  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about the relative position of common objects seen in the sky. The probe is designed to find out if students recognize how far away the stars are in relation to the Earth and the Moon.

Eberle, Francis; Tugel, Joyce; Keeley, Page

2007-01-01

296

Asteroseismology of Binary Stars  

NASA Astrophysics Data System (ADS)

The study of stellar oscillations, asteroseismology, enables us to draw conclusions on the inner structure of stars; thereby helping improve stellar models. Given that the majority of stars are found in binary or multiple systems, we expect to find many such systems containing pulsators. Binary stars, and in particular eclipsing binaries, play a crucial role in stellar astrophysics. Eclipse shapes, radial velocities, and other geometric properties of orbits are related to the physical properties of the components, such as radius and mass. These properties can, therefore, easily be derived from spectroscopic and photometric observations by simply applying the laws of physics and without relying on any assumptions of stellar-structure models. Hence, the understanding of eclipsing binary systems with pulsating components provide accurate constraints on the input physics for asteroseismic models. We will study nine different eclipsing binary stars containing pulsating components that range in masses from about 2-8 Mo. We will make use of high-precision photometry provided by the Kepler satellite and combine them with high-resolution spectroscopy gathered with the HERMES spectrograph mounted on the Mercator telescope, located on La Palma, Spain. The prospects of this challenging project will be presented and illustrated by the means of a case study.

Schmid, Valentina; Aerts, Conny; Debosscher, Jonas

2013-06-01

297

Bohr Sommerfeld star products  

NASA Astrophysics Data System (ADS)

We relate the Bohr Sommerfeld conditions to formal deformation quantization of symplectic manifolds by classifying star products adapted to some Lagrangian submanifold L, i.e. products preserving the classical vanishing ideal IL of L up to IL-preserving equivalences.

Carl, Michael

2008-05-01

298

Millet's Shooting Stars  

NASA Astrophysics Data System (ADS)

In this essay two paintings by the French artist Jean-Francois Millet are described. These paintings, Les Etoiles Filantes and Nuit Etoilée are particularly interesting since they demonstrate the rare artistic employment of the shooting-star image and metaphor.

Beech, M.

1988-12-01

299

The Stars of Heaven  

Microsoft Academic Search

Do a little armchair space travel, rub elbows with alien life forms, and stretch your mind to the furthest corners of our uncharted universe. With this astonishing guidebook, you don't have to be an astronomer to explore the mysteries of stars and their profound meaning for human existence. Clifford A. Pickover tackles a range of topics from stellar evolution to

Clifford A. Pickover

2004-01-01

300

Star Trek Physics  

NSDL National Science Digital Library

The authors suggest several ways to catch and hold student interest in physics. One excellent method is to use the television series Star Trek to extend the science curriculum. The beauty of this program is that the writers based their creations

Cole, Lynn; Radhe, Sue E.

2002-03-01

301

H-cluster stars  

NASA Astrophysics Data System (ADS)

The study of dense matter at ultrahigh density has a very long history, which is meaningful for us to understand not only cosmic events in extreme circumstances but also fundamental laws of physics. It is well known that the state of cold matter at supranuclear density depends on the non-perturbative nature of quantum chromodynamics (QCD) and is essential for modelling pulsars. A so-called H-cluster matter is proposed in this paper as the nature of dense matter in reality. In compact stars at only a few nuclear densities but low temperature, quarks could be interacting strongly with each other there. That might render quarks grouped in clusters, although the hypothetical quark clusters in cold dense matter have not been confirmed due to the lack of both theoretical and experimental evidence. Motivated by recent lattice QCD simulations of the H-dibaryons (with structure uuddss), we therefore consider here a possible kind of quark clusters, H-clusters, that could emerge inside compact stars during their initial cooling as the dominant components inside (the degree of freedom could then be H-clusters there). Taking into account the in-medium stiffening effect, we find that at baryon densities of compact stars H-cluster matter could be more stable than nuclear matter. We also find that for the H-cluster matter with lattice structure, the equation of state could be so stiff that it would seem to be `superluminal' in the most dense region. However, the real sound speed for H-cluster matter is in fact difficult to calculate, so at this stage we do not put constraints on our model from the usual requirement of causality. We study the stars composed of H-clusters, i.e. H-cluster stars, and derive the dependence of their maximum mass on the in-medium stiffening effect, showing that the maximum mass could be well above 2 M? as observed and that the resultant mass-radius relation fits the measurement of the rapid burster under reasonable parameters. Besides a general understanding of different manifestations of compact stars, we expect further observational and experimental tests for the H-cluster stars in the future.

Lai, X. Y.; Gao, C. Y.; Xu, R. X.

2013-06-01

302

Star Formation During Galaxy Formation  

NASA Astrophysics Data System (ADS)

Young galaxies are clumpy, gas-rich, and highly turbulent. Star formation appears to occur by gravitational instabilities in galactic disks. The high dispersion makes the clumps massive and the disks thick. The star formation rate should be comparable to the gas accretion rate of the whole galaxy, because star formation is usually rapid and the gas would be depleted quickly otherwise. The empirical laws for star formation found locally hold at redshifts around 2, although the molecular gas consumption time appears to be smaller, and mergers appear to form stars with a slightly higher efficiency than the majority of disk galaxies.

Elmegreen, B. G.

2011-11-01

303

Weighing the Smallest Stars  

NASA Astrophysics Data System (ADS)

VLT Finds Young, Very Low Mass Objects Are Twice As Heavy As Predicted Summary Thanks to the powerful new high-contrast camera installed at the Very Large Telescope, photos have been obtained of a low-mass companion very close to a star. This has allowed astronomers to measure directly the mass of a young, very low mass object for the first time. The object, more than 100 times fainter than its host star, is still 93 times as massive as Jupiter. And it appears to be almost twice as heavy as theory predicts it to be. This discovery therefore suggests that, due to errors in the models, astronomers may have overestimated the number of young "brown dwarfs" and "free floating" extrasolar planets. PR Photo 03/05: Near-infrared image of AB Doradus A and its companion (NACO SDI/VLT) A winning combination A star can be characterised by many parameters. But one is of uttermost importance: its mass. It is the mass of a star that will decide its fate. It is thus no surprise that astronomers are keen to obtain a precise measure of this parameter. This is however not an easy task, especially for the least massive ones, those at the border between stars and brown dwarf objects. Brown dwarfs, or "failed stars", are objects which are up to 75 times more massive than Jupiter, too small for major nuclear fusion processes to have ignited in its interior. To determine the mass of a star, astronomers generally look at the motion of stars in a binary system. And then apply the same method that allows determining the mass of the Earth, knowing the distance of the Moon and the time it takes for its satellite to complete one full orbit (the so-called "Kepler's Third Law"). In the same way, they have also measured the mass of the Sun by knowing the Earth-Sun distance and the time - one year - it takes our planet to make a tour around the Sun. The problem with low-mass objects is that they are very faint and will often be hidden in the glare of the brighter star they orbit, also when viewed in large telescopes. Astronomers have however found ways to overcome this difficulty. For this, they rely on a combination of a well-considered observational strategy with state-of-the-art instruments. High contrast camera First, astronomers searching for very low mass objects look at young nearby stars because low-mass companion objects will be brightest while they are young, before they contract and cool off. In this particular case, an international team of astronomers [1] led by Laird Close (Steward Observatory, University of Arizona), studied the star AB Doradus A (AB Dor A). This star is located about 48 light-years away and is "only" 50 million years old. Because the position in the sky of AB Dor A "wobbles", due to the gravitational pull of a star-like object, it was believed since the early 1990s that AB Dor A must have a low-mass companion. To photograph this companion and obtain a comprehensive set of data about it, Close and his colleagues used a novel instrument on the European Southern Observatory's Very Large Telescope. This new high-contrast adaptive optics camera, the NACO Simultaneous Differential Imager, or NACO SDI [2], was specifically developed by Laird Close and Rainer Lenzen (Max-Planck-Institute for Astronomy in Heidelberg, Germany) for hunting extrasolar planets. The SDI camera enhances the ability of the VLT and its adaptive optics system to detect faint companions that would normally be lost in the glare of the primary star. A world premiere ESO PR Photo 03/05 ESO PR Photo 03/05 Infrared image of AB Doradus A and its companion [Preview - JPEG: 400 x 406 pix - 99k] [Normal - JPEG: 800 x 812 pix - 235k] Caption: ESO PR Photo 03/05 is an enhanced, false-colour near-infrared image of AB Dor A and C. The faint companion "AB Dor C" - seen as the pink dot at 8 o'clock - is 120 times fainter than its primary star. The tiny separation between A and C, only 0.156 arcsec, is smaller than a one Euro coin seen at 20 km distance. Nevertheless, the new NACO SDI camera was able to

2005-01-01

304

Black Holes and Neutron Stars  

NASA Astrophysics Data System (ADS)

Black holes and neutron stars are the compact remnants of massive stars. They represent one of the key intersections between astronomy and fundamental physics - both are classes of objects which are sufficiently compact that Newtonian gravity cannot be used to describe the forces near their surfaces. The structure of neutron stars furthermore presents one of the few key tests of the equation of state of nuclear matter. This chapter will review some of the key theoretical results underpinning the current understanding of neutron stars and black holes. It will also describe the observations of neutron stars and black holes both in isolation (as thermal emitters and as radio pulsars for the case of neutron stars) and in close binaries, where accretion processes can make these objects bright X-ray sources. Additionally, this chapter will detail the formation processes of both neutron stars and black holes in general, and also the formation of close binaries containing such objects.

Maccarone, Thomas J.

305

Activity on young stars.  

NASA Astrophysics Data System (ADS)

Simultaneous photometry and spectroscopy were made of 6 young stars during two observing periods mainly to study short-term variability on time-scales from minutes to a few hours. The material includes two classical T Tauri stars (CTTS): SY Ori and VW Cha; three T Tauri stars with weak emission line spectra (WTTS): San 1, SZ Cha and ADA 481 and one post-T Tauri candidate: HD 70309B. Both UBV and Stroemgren photometry was made. In the visible spectral region we resolved rapid fluctuations - events - with total amplitudes of about 5% (0.05 magnitudes). In the ultraviolet, the corresponding limit of detection was usually <=10%. On the basis of totally about 100 hours of monitoring we conclude that the normal state of these stars is that they are completely constant in brightness or that they vary only slowly with small amplitudes over several hours. Only a few percent of the time, on the average, is a given star caught at brightness changes >=0.2mag. during one night. No event reached a total amplitude of >=0.3mag. VW Cha is the most active star, but no events were seen on SY Ori and HD 70309B. This confirms earlier indications that powerful "flaring" on T Tauri stars is not frequent. We make a detailed study of all events and find two types of slow events, usually with d(U or u)/dt<=0.1mag/hour. One is caused by changes in the continuous emission (the veiling) superimposed on the stellar photospheric spectrum and operates mainly on VW Cha. These events have nothing to do with stellar surface flares of the type observed on flare stars and we suggest that they originate from inhomogeneous mass accretion from a circumstellar disk to the stellar surface. The time-scales support models with magnetically controlled accretion along the stellar dipole field to rings or spots at the stellar surface. The other type of event appears to originate from relatively rapid changes in the opacity of circumstellar dust in the line-of-sight to the star. This effect dominates on SZ Cha, a WTTS surrounded by a substantial dust reservoir. Also for the rapid events we distinguish two types. On two WTTS we detected a few flare-like events produced by a sudden increase in emission in the Balmer continuum and the Balmer lines and no detectable change of the continuum long-ward of the Balmer jump. With only UBV photometry the Balmer flares could erronously been interpreted as very hot blackbody radiators. We suggest that these events are genuine surface flares with total energies of 10^33^ to 10^34^erg, and discuss the implication of energy supply. On ADA 481 we detected 2 flare-like events in white light. If these are due to the ignition of a source of blackbody radiation, the inferred temperature of the flare is low compared to what is normally observed for flare stars. Even though the events are rare and have small total amplitudes in UV, they are extremely powerful, with the same total energies as the largest flares seen on flare stars. The flare stars may show much larger changes in UV, but the difference comes from the lower contrast of the flares on the TTS. If all TTS have surface magnetic activity similar to the flare stars, only the radii being larger, then we conclude that the frequency distribution of the flare-like events on WTTS are similar to flare stars in the field, but much higher than for the dwarfs in the Pleiades. No flare-like event was seen on the CTTS and we discuss possible implications. For the long-term changes (over days) we conclude that very dark spots on the rotating surfaces of SY Ori and San 1 dominates, while VW Cha varies because of variable veiling, but with an uncertain period. For SZ Cha variable circumstellar extinction operates, also in phase with the hydrogen line absorption. The situation for ADA 481 is still unclear. HD 70309B did not vary.

Gahm, G. F.; Loden, K.; Gullbring, E.; Hartstein, D.

1995-09-01

306

Massive star forming environments  

NASA Astrophysics Data System (ADS)

We present a study of the earliest stages of massive star formation, in which we focus on Infrared Dark Clouds (IRDCs) and young massive clusters. We present Very Large Array spectral line observations of ammonia (NH 3) and CCS toward four IRDCs. The NH3 lines provide diagnostics of the temperature and density structure within IRDCs. Based upon the NH 3 column density, IRDCs have masses of ˜ 103 to 10 4 M? . We detect twenty NH3 clumps within four IRDCs, with radii < 0.3 pc and masses ˜ 102 to 103 M? . A majority of the clumps are associated with signatures of star formation: 24 mum emission, H2O masers, 8 GHz continuum emission, and/or outflows. The physical properties of the clumps are consistent with massive cluster progenitors. From the NH3 emission we also find distinct velocity components, or "subclouds", within each IRDC. Although they appear ubiquitous in IRDCs, subclouds have not previously been reported. Subclouds may represent an intermediate stage of molecular cloud fragmentation, between filamentary structure and clump formation. The spatial distribution of the CCS and NH3 emission is generally anti-correlated, with the NH 3 predominantly in the high-density clumps, and CCS in lower-density gas. This spatial distribution may be explained by chemical evolution models for star forming gas, where in chemically young clouds with recently disrupted gas CCS forms quickly. In early clump formation CCS is abundant and in the centers of more evolved star forming clumps CCS is depleted. Near infrared observations of three embedded massive star forming regions are presented from the Near Infrared Imager (NIRIM) camera on the 3.5 m WIYN telescope. We report J, H, and K' band photometry in the clusters AFGL437, AFGL5180, and AFGL5142 and use these results to probe the stellar populations, extinction, and ages of the clusters. We find that all three clusters suffer significant extinction (AK ˜1), have ages ? 5 Myr, and are actively forming stars. We conclude that the properties of these embedded clusters are consistent with their evolving from IRDC clumps.

Devine, Kathryn Elizabeth

2010-12-01

307

Hyperons and neutron stars  

NASA Astrophysics Data System (ADS)

In this work we briefly review some of the effects of hyperons on neutron and proto-neutron star properties. We revise the problem of the strong softening of the EoS, and the consequent reduction of the maximum mass, due to the presence of hyperons, a puzzle which has become more intriguing due the recent measurements of the unusually high masses of the millisecond pulsars PSR J1614-2230 (1.97±0.04M?) and PSR J1903+0327 (1.667±0.021M?). We examine also the role of hyperons on the cooling properties of newly born neutron stars and on the so-called r-mode instability.

Vidaña, Isaac

2013-09-01

308

Interacting Star Clusters  

NASA Astrophysics Data System (ADS)

The early evolution of star cluster formation is a complicated phase in which several astrophysical processes with different time-scales operate simultaneously. From kinematical data of the young massive cluster R136 it was recently found that the cluster is in virial equilibrium; despite its young age it has already settled in a dynamical equilibrium. Somewhat surprisigly, about a quarter of the (kinetic) energy is in a rotational component. From HST observations of R136 a small clump of stars to the North-East of R136 was found, with indications that this clump is interacting/merging with R136. In this talk I will discuss whether these two observational results should be connected, i.e. whether the rotation signal is due to an ongoing "dry" interaction. The results are illustrated with a suite of N-body simulations of R136 like systems.

Gieles, M.

2013-06-01

309

Double Star Sketching  

NASA Astrophysics Data System (ADS)

The details of your growing record of double star observations can easily be kept in a spreadsheet with columns included for position angle, separation, magnitude, and color. Those entries provide the raw data needed to describe your stellar journeys. However, the essence of what draws you to doubles may not be as obvious when you review your notes. What inspires you to observe double stars? Is it the challenge of resolving a close pair, or pulling a faint secondary out of its companion's glare? Or is it the stunning beauty of a colorful duo or closely matched twins? Do you enjoy tracking the progress of short-period doubles? All of these passions and more can be readily captured by sketches in a way that vividly supplements your tabular data.

Perez, Jeremy; Argyle, R. W.

310

Pulsating Stars Harbouring Planets  

NASA Astrophysics Data System (ADS)

Why bother with asteroseismology while studying exoplanets? There are several answers to this question. Asteroseismology and exoplanetary sciences have much in common and the synergy between the two opens up new aspects in both fields. These fields and stellar activity, when taken together, allow maximum extraction of information from exoplanet space missions. Asteroseismology of the host star has already proved its value in a number of exoplanet systems by its unprecedented precision in determining stellar parameters. In addition, asteroseismology allows the possibility of discovering new exoplanets through time delay studies. The study of the interaction between exoplanets and their host stars opens new windows on various physical processes. In this review I will summarize past and current research in exoplanet asteroseismology and explore some guidelines for the future.

Moya, A.

311

Pulsating stars harbouring planets  

NASA Astrophysics Data System (ADS)

Why bother with asteroseismology while studying exoplanets? There are several answers to this question. Asteroseismology and exoplanetary sciences have much in common and the synergy between the two opens up new aspects in both fields. These fields and stellar activity, when taken together, allow maximum extraction of information from exoplanet space missions. Asteroseismology of the host star has already proved its value in a number of exoplanet systems by its unprecedented precision in determining stellar parameters. In addition, asteroseismology allows the possibility of discovering new exoplanets through time delay studies. The study of the interaction between exoplanets and their host stars opens new windows on various physical processes. In this review I will summarize past and current research in exoplanet asteroseismology and explore some guidelines for the future.

Moya, A.

2013-04-01

312

Orthographic star coordinates.  

PubMed

Star coordinates is a popular projection technique from an nD data space to a 2D/3D visualization domain. It is defined by setting n coordinate axes in the visualization domain. Since it generally defines an affine projection, strong distortions can occur: an nD sphere can be mapped to an ellipse of arbitrary size and aspect ratio. We propose to restrict star coordinates to orthographic projections which map an nD sphere of radius r to a 2D circle of radius r. We achieve this by formulating conditions for the coordinate axes to define orthographic projections, and by running a repeated non-linear optimization in the background of every modification of the coordinate axes. This way, we define a number of orthographic interaction concepts as well as orthographic data tour sequences: a scatterplot tour, a principle component tour, and a grand tour. All concepts are illustrated and evaluated with synthetic and real data. PMID:24051828

Lehmann, Dirk J; Theisel, Holger

2013-12-01

313

Dynamics in Young Star Clusters: From Planets to Massive Stars  

NASA Astrophysics Data System (ADS)

The young star clusters we observe today are the building blocks of a new generation of stars and planets in our Galaxy and beyond. Despite their fundamental role we still lack knowledge about the conditions under which star clusters form and the impact of these often harsh environments on the evolution of their stellar and substellar members. We demonstrate the vital role numerical simulations play to uncover both key issues. Using dynamical models of different star cluster environments we show the variety of effects stellar interactions potentially have. Moreover, our significantly improved measure of mass segregation reveals that it can occur rapidly even for star clusters without substructure. This finding is a critical step to resolve the controversial debate on mass segregation in young star clusters and provides strong constraints on their initial conditions.

Olczak, C.; Spurzem, R.; Henning, Th.; Kaczmarek, T.; Pfalzner, S.; Harfst, S.; Portegies Zwart, S.

314

Star of Bethlehem  

Microsoft Academic Search

Star of Bethlehem are grown as cut flower and potted plant crops throughout the world. A relatively new crop, Ornithogalum is favored for its unusual flower shapes, coloration, and use for holiday (Christmas) floral designs. The leaves are variable,\\u000a ranging from grass-like to strap-shaped. While the inflorescence is a raceme, its appearance changes due to varying floret\\u000a peduncle lengths. Most

Gail Littlejohn

315

SIRTF autonomous star tracker  

Microsoft Academic Search

Two redundant AST-301 autonomous star trackers (AST) serve as the primary attitude sensors for JPL's space infrared telescope facility (SIRTF). These units, which employ a 1553B interface to output their attitude quaternions and uncertainty at a 2 Hz rate, provide a 1 sigmaaccuracy of better than 0.18, 0.18, and 5.1 arcsec about their X, Y, and Z axes, respectively. This

Roelof W. H. van Bezooijen

2003-01-01

316

GALEX and star formation  

Microsoft Academic Search

Wide-field far-UV (FUV, 1344–1786 Å) and near-UV (NUV, 1771–2831 Å) imaging from GALEX provides a deep, comprehensive view of the young stellar populations in hundreds of nearby galaxies, shedding new light on\\u000a the process of star formation (SF) in different environments, and on the interplay between dust and SF. GALEX’s FUV-NUV color is extremely sensitive to stellar populations of ages up to

Luciana Bianchi

2011-01-01

317

Dilepton Measurements at STAR  

NASA Astrophysics Data System (ADS)

In the study of hot and dense nuclear matter, created in relativistic heavy-ion collisions, dilepton measurements play an essential role. Leptons, when compared to hadrons, have only little interaction with the strongly interacting system. Thus, dileptons provide ideal penetrating probes that allow the study of such a system throughout its space-time evolution. In the low mass range (Mll < 1.1 GeV/c2), the dominant source of dileptons originates from the decay of vector mesons which may see effects from chiral symmetry restoration. In the intermediate mass range (1.1 < Mll < 3.0 GeV/c2), the main contributions to the mass spectrum are expected to originate from the thermal radiation of a quark-gluon plasma as well as the decays of charm mesons. In the high mass range (Mll > 3.0 GeV/c2), dilepton measurements are expected to see contributions from primordial processes involving heavy quarks, and Drell-Yan production. With the introduction of the Time-of-Flight detector, the STAR detector has been able to perform large acceptance, high purity electron identification. In this contribution, we will present STAR's recent dielectron measurements in the low and intermediate mass range for RHIC beam energies ranging between 19.6 and 200 GeV. Compared to electrons, muon measurements have the advantage of reduced bremsstrahlung radiation in the surrounding detector materials. With the upcoming detector upgrades, specifically the muon detector (MTD), STAR will be able to include such measurements in its (di-)lepton studies. We will discuss the future dilepton program at STAR and the physics cases for these upgrades.

Geurts, Frank; STAR Collaboration

2013-08-01

318

Adsorption of star polymers  

NASA Astrophysics Data System (ADS)

The adsorption of star polymers on a flat solid surface is analyzed by means of scalling arguments based on the Daoud-Cotton blob model. For the adsorption of a single star, consisting of f arms comprising each N monomers, we distinguish three regimes determined by the adsorption energy of a monomer at the surface, ? kT. 1) Strong adsorption characterized by the full adsorption of all arms occurs for ? > (f/N)^{3/5}. 2) A “Sombrero” like structure comprising f_ads fully adsorbed arms and f{-}f_ads free arms is obtained for (f/N)^{3/5}> ? > f^{9/20}/N^{3/5}. 3) Weakly adsorbed stars retain, essentially, the structure of a free star. This regime occurs for ? < f^{9/20}/N^{3/5}. The weakly adsorbed structure may also exist as a metastable state if ? > f^{9/5}/N^{3/5}. Nous étudions l'adsorption de polymères en étoile sur une surface solide en utilisant une approche de lois d'échelles basée sur le modèle de blobs de Daoud et Cotton. Pour une étoile formée de f bras contenant chacun N monomères, nous distinguons trois régimes suivant la valeur de l'énergie d'adsorption d'un monomère sur la surface ? kT. 1) L'adsorption forte caractérisée par une adsorption complète de tous les bras se produit lorsque ? > (f/N)^{3/5}. 2) Une structure en “sombrero” avec f_ads bras adsorbés et f{-}f_ads bras libres est obtenue si f^{9/20}/N^{3/5}? < (f/N)^{3/5}. 3) Les étoiles faiblement adsorbées gardent une structure très similaire à celle des étoiles libres en solution. Ce régime existe si ? < f^{9/20}/N^{3/5}. La structure correspondant aux étoiles faiblement adsorbées peut aussi exister comme un état métastable si ? > f^{9/5}/N^{3/5}.

Halperin, A.; Joanny, J. F.

1991-06-01

319

Life Cycle of Stars  

NSDL National Science Digital Library

This lesson plan is part of the Center for Educational Resources (CERES), a series of web-based astronomy lessons created by a team of master teachers, university faculty, and NASA researchers. In this lesson, students analyze characteristics that indicate human life cycles, then apply these principles to various NASA images of stars to synthesize patterns of stellar life cycles. This lesson contains expected outcomes for students, materials, background information, follow-up questions, and assessment procedures.

Tuthill, George; Obbink, Kim

320

PhotonStar project  

NASA Astrophysics Data System (ADS)

The PhotonStar SETI project is an enterprise to detect extraterrestrial laser signals that involves many individual small telescopes acting together as a geographically diverse large array which together comprise a large collection area, thereby, offering a better chance of detection if signals exist. Widely separated small telescopes, each with a sensitive photon detection capability, can be aimed simultaneously at the same star system with precise timing that enables looking at the same time for short pulse detection. Each individual telescope can be located via GPS so that the differential distance from the star compared to every other telescope can be determined beforehand. Coordination via the Internet would enable each telescope to operate as one element of the array. This project allows direct public participation by amateur astronomers into the search for extraterrestrial intelligence as there are thousands of telescopes of eight inches or greater in use, so that the total collection area can be very substantial with public participation. In this way, each telescope is part of a larger array with data being sent via the Internet to a central station. This approach is only feasible now with the advent of GPS, the Internet, and relatively low- cost single photon detector technology.

Ross, Monte; Kingsley, Stuart A.

2001-08-01

321

Stable dark energy stars  

NASA Astrophysics Data System (ADS)

The gravastar picture is an alternative model to the concept of a black hole, where there is an effective phase transition at or near where the event horizon is expected to form, and the interior is replaced by a de Sitter condensate. In this work a generalization of the gravastar picture is explored by considering matching of an interior solution governed by the dark energy equation of state, ? ? p/? < -1/3, to an exterior Schwarzschild vacuum solution at a junction interface. The motivation for implementing this generalization arises from the fact that recent observations have confirmed an accelerated cosmic expansion, for which dark energy is a possible candidate. Several relativistic dark energy stellar configurations are analysed by imposing specific choices for the mass function. The first case considered is that of a constant energy density, and the second choice that of a monotonic decreasing energy density in the star's interior. The dynamical stability of the transition layer of these dark energy stars to linearized spherically symmetric radial perturbations about static equilibrium solutions is also explored. It is found that large stability regions exist that are sufficiently close to where the event horizon is expected to form, so that it would be difficult to distinguish the exterior geometry of the dark energy stars, analysed in this work, from an astrophysical black hole.

Lobo, Francisco S. N.

2006-03-01

322

The Double Star mission  

NASA Astrophysics Data System (ADS)

The Double Star Programme (DSP) was first proposed by China in March, 1997 at the Fragrant Hill Workshop on Space Science, Beijing, organized by the Chinese Academy of Science. It is the first mission in collaboration between China and ESA. The mission is made of two spacecraft to investigate the magnetospheric global processes and their response to the interplanetary disturbances in conjunction with the Cluster mission. The first spacecraft, TC-1 (Tan Ce means "Explorer"), was launched on 29 December 2003, and the second one, TC-2, on 25 July 2004 on board two Chinese Long March 2C rockets. TC-1 was injected in an equatorial orbit of 570x79000 km altitude with a 28° inclination and TC-2 in a polar orbit of 560x38000 km altitude. The orbits have been designed to complement the Cluster mission by maximizing the time when both Cluster and Double Star are in the same scientific regions. The two missions allow simultaneous observations of the Earth magnetosphere from six points in space. To facilitate the comparison of data, half of the Double Star payload is made of spare or duplicates of the Cluster instruments; the other half is made of Chinese instruments. The science operations are coordinated by the Chinese DSP Scientific Operations Centre (DSOC) in Beijing and the European Payload Operations Service (EPOS) at RAL, UK. The spacecraft and ground segment operations are performed by the DSP Operations and Management Centre (DOMC) and DSOC in China, using three ground station, in Beijing, Shanghai and Villafranca.

Liu, Z. X.; Escoubet, C. P.; Pu, Z.; Laakso, H.; Shi, J. K.; Shen, C.; Hapgood, M.

2005-11-01

323

Minimal surfaces over stars  

NASA Astrophysics Data System (ADS)

A JS surface is a minimal graph over a polygonal domain that becomes infinite in magnitude at the domain boundary. Jenkins and Serrin characterized the existence of these minimal graphs in terms of the signs of the boundary values and the side-lengths of the polygon. For a convex polygon, there can be essentially only one JS surface, but a non-convex domain may admit several distinct JS surfaces. We consider two families of JS surfaces corresponding to different boundary values, namely JS0 and JS1, over domains in the form of regular stars. We give parameterizations for these surfaces as lifts of harmonic maps, and observe that all previously constructed JS surfaces have been of type JS0. We give an example of a JS1 surface that is a new complete embedded minimal surface generalizing Scherk's doubly periodic surface, and show also that the JS0 surface over a regular convex 2n-gon is the limit of JS1 surfaces over non-convex stars. Finally we consider the construction of other JS surfaces over stars that belong neither to JS0 nor to JS1.

McDougall, Jane; Schaubroeck, Lisbeth

2008-04-01

324

Efficiencies of Low-Mass Star and Star Cluster Formation  

Microsoft Academic Search

Using a quantitative model for bipolar outflows driven by hydromagnetic\\u000aprotostellar winds, we calculate the efficiency of star formation assuming that\\u000aavailable gas is either converted into stars or ejected in outflows. We\\u000aestimate the efficiency of a single star formation event in a protostellar\\u000acore, finding 25%-70% for cores with various possible degrees of flattening.\\u000aThe core mass function

Christopher D. Matzner; Christopher F. McKee

2000-01-01

325

RR Lyrae Stars, Metal-Poor Stars, and the Galaxy  

NASA Astrophysics Data System (ADS)

This online book contains the proceedings of a meeting on "RR Lyrae Stars, Metal-Poor Stars, and the Galaxy" held at the Carnegie Observatories, Pasadena, California, in January 2011, to honor the 80th year of George W. Preston III. The book comprises the 5th volume of the Carnegie Observatories Astrophysics Series, and contains reviews and research articles on recent developments in the area of RR Lyrae stars, including results from the Kepler space mission. Review and research articles on metal-poor stars and Galactic structure are also included.

McWilliam, Andrew

2011-08-01

326

RUNAWAY STARS, HYPERVELOCITY STARS, AND RADIAL VELOCITY SURVEYS  

SciTech Connect

Runaway stars ejected from the Galactic disk populate the halo of the Milky Way. To predict the spatial and kinematic properties of runaways, we inject stars into a Galactic potential, compute their trajectories through the Galaxy, and derive simulated catalogs for comparison with observations. Runaways have a flattened spatial distribution, with higher velocity stars at Galactic latitudes less than 30{sup 0}. Due to their shorter stellar lifetimes, massive runaway stars are more concentrated toward the disk than low mass runaways. Bound (unbound) runaways that reach the halo probably originate from distances of 6-12 kpc (10-15 kpc) from the Galactic center, close to the estimated origin of the unbound runaway star HD 271791. Because runaways are brighter and have smaller velocities than hypervelocity stars (HVSs), radial velocity surveys are unlikely to confuse runaway stars with HVSs. We estimate that at most one runaway star contaminates the current sample. We place an upper limit of 2% on the fraction of A-type main-sequence stars ejected as runaways.

Bromley, Benjamin C. [Department of Physics, University of Utah, 115 S 1400 E, Rm 201, Salt Lake City, UT 84112 (United States); Kenyon, Scott J.; Brown, Warren R.; Geller, Margaret J., E-mail: bromley@physics.utah.ed, E-mail: skenyon@cfa.harvard.ed, E-mail: wbrown@cfa.harvard.ed, E-mail: mgeller@cfa.harvard.ed [Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States)

2009-12-01

327

The Birth of Stars and Planets  

NASA Astrophysics Data System (ADS)

Part I. Stars and Clusters: 1. Our Cosmic Backyard; 2. Looking up at the night sky; 3. The dark clouds of the Milky Way; 4. Infant stars; 5. Companions in birth: binary stars; 6. Outflows from young stars; 7. Towards adulthood; 8. The social life of stars: stellar groups; 9. Chaos in the nest: The brief lives of massive stars. Part II. Planetary Systems: 10. Solar systems in the making; 11. Messengers from the past; 12. Hazards to planet formation; 13. Planets around other stars; Part III. The Cosmic Context: 14. Cosmic cycles; 15. Star formation in galaxies; 16. The first stars and galaxies; 17. Astrobiology, origins, and SETI.

Bally, John; Reipurth, Bo

2006-08-01

328

Investigating the Highest Proper Motion Stars  

Microsoft Academic Search

There currently are 601 stars (502 systems) with proper motion faster than 1 arcsec\\/year (hereafter, MOTION stars). Among these MOTION stars, there are 186 systems (37%) without complete VRI photometric information on a standard system. We propose to obtain VRI band photometry from both CTIO and KPNO in order to characterize these stars. 75% of MOTION stars are estimated to

Wei-Chun Jao; Todd Henry; John Subasavage; Jacob Bean

2002-01-01

329

The Constellations and Their Stars  

NSDL National Science Digital Library

This comprehensive site looks at constellations, stars, the Milky Way, and Messier objects. Constellations are listed alphabetically as well as by month, and data covers star names and Messier objects in the constellation, the meaning of their names, and stories behind the constellation. There are also links to a regular star chart, and an interactive star chart where the constellation can be viewed in a variety of ways. Stars are listed alphabetically or by catalog number, and link to star name, designation, coordinates (declination and right ascension), brightness, and spectral type. There is also a description of known Messier objects, Milky Way photographs, a constellation abbreviation table, a Moon phases demonstration, and references and links for more information.

330

Do Iron Stars Really Exist?  

NASA Astrophysics Data System (ADS)

Only two stars have been classified as Iron Stars: XX Oph and AS 325. This distinction is bestowed upon them as their optical spectra consist entirely of a forest of emission lines, most of which are due to the ionized metals of iron, chromium, and titanium. Over the years, XX Oph (Merrill's iron star) and AS 325 have received various classifications including spectral types from B to M and even thought to be binary stars. Using new optical and near-IR spectroscopy we have finally observed the stellar photospheres in these two objects. They appear to be evolved stars trapped in a dense region of the Rho Oph star forming region. Taking our multi-wavelength observations plus past work by others, we have developed a new model for what these two unique objects really are.

Peña, M. A.; Cool, R. J.; Howell, S. B.; Adamson, A.

2004-12-01

331

Star Forming Regions in Cepheus  

NASA Astrophysics Data System (ADS)

The northern Milky Way in the constellation of Cepheus (100° ? l ? 120°; 0° ? b ? 20°) contains several star forming regions. The molecular clouds of the Cepheus Flare region at b > 10°, are sites of low and intermediate mass star formation located between 200 and 450 pc from the Sun. Three nearby OB associations, Cep OB2, Cep OB3, Cep OB4, located at 600--800 pc, are eac= h involved in forming stars, like the well known high mass star forming regio= n S 140 at 900 pc. The reflection nebula NGC 7129 around 1 kpc harbors young, compact clusters of low and intermediate mass stars. The giant star forming complex NGC 7538 and the young open cluster NGC 7380, associated with the Perseus arm, are located at d > 2 kpc.

Kun, M.; Kiss, Z. T.; Balog, Z.

2008-12-01

332

Massive star clusters in galaxies.  

PubMed

The ensemble of all star clusters in a galaxy constitutes its star cluster system. In this review, the focus of the discussion is on the ability of star clusters, particularly the systems of old massive globular clusters (GCs), to mark the early evolutionary history of galaxies. I review current themes and key findings in GC research, and highlight some of the outstanding questions that are emerging from recent work. PMID:20083511

Harris, William E

2010-02-28

333

Binary Stars in Globular Clusters  

NASA Astrophysics Data System (ADS)

Globular clusters have long been known to be among the richest stellar groupings within our Galaxy, but for many years they were believed to be largely devoid of the most minimal stellar group: binary stars (see BINARY STARS: OVERVIEW). For many years, the only evidence that any binaries existed in these clusters came from the presence of BLUE STRAGGLERS—stars that appear to be significantly you...

Mateo, M.; Murdin, P.

2000-11-01

334

Star Formation in Spiral Arms  

Microsoft Academic Search

The origin and types of spiral arms are reviewed with an emphasis on the\\u000aconnections between these arms and star formation. Flocculent spiral arms are\\u000amost likely the result of transient instabilities in the gas that promote dense\\u000acloud formation, star formation, and generate turbulence. Long irregular spiral\\u000aarms are usually initiated by gravitational instabilities in the stars, with\\u000athe

Bruce G. Elmegreen

2011-01-01

335

Nuclear Star Clusters & Black Holes  

NASA Astrophysics Data System (ADS)

We summarize the recent results of our survey of the nearest nuclear star clusters. The purpose of the survey is to understand nuclear star cluster formation mechanisms and constrain the presence of black holes using adaptive optics assisted integral field spectroscopy, optical spectroscopy, and HST imaging in 13 galaxies within 5 Mpc. We discuss the formation history of the nuclear star cluster and possible detection of an intermediate mass BH in NGC 404, the nearest S0 galaxy.

Seth, Anil; Cappellari, Michele; Neumayer, Nadine; Caldwell, Nelson; Bastian, Nate; Olsen, Knut; Blum, Robert; Debattista, Victor P.; McDermid, Richard; Puzia, Thomas; Stephens, Andrew

2010-06-01

336

Proper Motions of Hypervelocity Stars  

NASA Astrophysics Data System (ADS)

I will present preliminary measurements of HST-based proper motions for 15 hypervelocity massive young stars that appear to have been ejected from the center of the Galaxy. Measurement of their proper motions can confirm their Galactic-center origin and tell us about the shape of the Galaxy's dark-matter potential. In order to measure absolute motions for these stars, we must carefully measure the displacement of the stars with respect to background galaxies in frames separated by several years.

Anderson, Jay; Gnedin, Oleg; Bond, Howard

2013-06-01

337

The Elements: Forged in Stars  

NSDL National Science Digital Library

All the stars in the universe, including the Sun, are nuclear furnaces fueled by fusion. Beginning with the fusion of hydrogen and continuing with fusion of successively heavier elements, stars form all the naturally occurring elements heavier than hydrogen and helium. This video segment illustrates the critical role that stars play in creating the elements, and describes the process of nucleosynthesis, in which increasingly heavier elements up through iron are formed, at which point the star collapses and explodes in a supernova, during which elements heavier than iron are created. The segment is three minutes forty-two seconds in length. A background essay and discussion questions are included.

338

Photometry of astrometric reference stars  

NASA Astrophysics Data System (ADS)

UBVRI, DDO, and uvby, H-beta photometry of astrometric reference stars is presented. Spectral types and luminosity classifications made from the colors are used to determine their spectroscopic parallaxes. In this paper, colors for 309 stars in 25 regions are given, and classifications for 210 stars have been made. These stars form reference frames in the Allegheny Observatory Multichannel Astrometric Photometer astrometric program, and in the Praesepe cluster reduced by Russell (1976). It is found that the present photometric spectral types are reliable to within 2.5 spectral subclasses.

Castelaz, Michael W.; Persinger, Tim; Stein, John W.; Prosser, James; Powell, Harry D.

1991-12-01

339

Flattest Star Ever Seen  

NASA Astrophysics Data System (ADS)

VLT Interferometer Measurements of Achernar Challenge Stellar Theory Summary To a first approximation, planets and stars are round. Think of the Earth we live on. Think of the Sun, the nearest star, and how it looks in the sky. But if you think more about it, you realize that this is not completely true. Due to its daily rotation, the solid Earth is slightly flattened ("oblate") - its equatorial radius is some 21 km (0.3%) larger than the polar one. Stars are enormous gaseous spheres and some of them are known to rotate quite fast, much faster than the Earth. This would obviously cause such stars to become flattened. But how flat? Recent observations with the VLT Interferometer (VLTI) at the ESO Paranal Observatory have allowed a group of astronomers [1] to obtain by far the most detailed view of the general shape of a fast-spinning hot star, Achernar (Alpha Eridani) , the brightest in the southern constellation Eridanus (The River). They find that Achernar is much flatter than expected - its equatorial radius is more than 50% larger than the polar one! In other words, this star is shaped very much like the well-known spinning-top toy, so popular among young children. The high degree of flattening measured for Achernar - a first in observational astrophysics - now poses an unprecedented challenge for theoretical astrophysics . The effect cannot be reproduced by common models of stellar interiors unless certain phenomena are incorporated, e.g. meridional circulation on the surface ("north-south streams") and non-uniform rotation at different depths inside the star. As this example shows, interferometric techniques will ultimately provide very detailed information about the shapes, surface conditions and interior structure of stars . PR Photo 15a/03 : The VLT Interferometer configuration for the Achernar measurements PR Photo 15b/03 : Achernar's "profile" , as measured by the VLTI. PR Photo 15c/03 : Models of Achernar's spatial shape. VLTI observations of Achernar ESO PR Photo 15a/03 ESO PR Photo 15a/03 [Preview - JPEG: 400 x 502 pix - 40k [Normal - JPEG: 800 x 1004 pix - 216k] Caption :PR Photo 15a/03 shows the configuration of the VLT Interferometer (VLTI) for the measurements of Achernar , described in this press release. The moveable, 40-cm test telescopes were positioned at specific "stations" (E0 + G1; B3 + M0; with baselines of 66 m and 140 m, respectively), allowing contiguous measurements in two nearly perpendicular directions. The two light beams were then sent via the path-compensating VLTI Delay Lines to the VINCI test instrument where they combined to form interferometric fringes. The positions of the four 8.2-m VLT Unit Telescopes are indicated by numbered circles. Test observations with the VLT Interferometer (VLTI) at the Paranal Observatory proceed well [2], and the astronomers have now begun to exploit many of these first measurements for scientific purposes. One spectacular result, just announced, is based on a series of observations of the bright, southern star Achernar (Alpha Eridani; the name is derived from "Al Ahir al Nahr" = "The End of the River"), carried out between September 11 and November 12, 2002. The two 40-cm siderostat test telescopes that served to obtain "First Light" with the VLT Interferometer in March 2001 were also used for these observations. They were placed at selected positions on the VLT Observing Platform at the top of Paranal to provide a "cross-shaped" configuration with two "baselines" of 66 m and 140 m, respectively, at 90° angle, cf. PR Photo 15a/03 . At regular time intervals, the two small telescopes were pointed towards Achernar and the two light beams were directed to a common focus in the VINCI test instrument in the centrally located VLT Interferometric Laboratory. Due to the Earth's rotation during the observations, it was possible to measure the angular size of the star (as seen in the sky) in different directions. Achernar's profile ESO PR Photo 15b/03 ESO PR Photo 15b/03 [

2003-06-01

340

From gas to stars: regulation of star formation  

Microsoft Academic Search

The author reviews recent progress in our understanding of the empirical form and physical basis of the star formation law, and identifies some of the key issues for future work. The successes and failures of the Schmidt law are reviewed, with emphasis on those problems for which the Schmidt law does serve as a useful parametrization of the star formation

R. C. Kennicutt

1997-01-01

341

How to Cook a Star: The reason stars shine  

NSDL National Science Digital Library

The site discusses the eraly theories that attempted to explain why the sun shines. By the end of the article the author discusses the process of nuclear fusion in the sun and other stars. At the end of the article there is a link to another articel that discusses what happens when stars run out of hydrogen.

Tung, Brian

2007-01-04

342

WNLh Stars - The Most Massive Stars in the Universe?  

NASA Astrophysics Data System (ADS)

We propose to conclude our intensive and complete time-dependent spectroscopic study of all 47 known WNL stars in the LMC, an ideal laboratory to study the effect of lower ambient metallicity, Z, on stellar evolution. WNL stars are luminous, cooler WR stars of the nitrogen sequence. This will allow us to: 1) determine the binary frequency. The Roche-lobe overflow (RLOF) mechanism in close binaries is predicted to be responsible for the formation of a significant fraction of WR stars in low Z environments such as the LMC. 2) determine the masses. Since some of these stars (denoted WNL(h) or WNLh) are supposed to be hydrogen-burning and thus main-sequence stellar objects of the highest luminosity, they may be the most massive stars known. 3) study wind-wind collision (WWC) effects in WR+O binaries involving very luminous WNL stars with strong winds. Interesting in itself as a high-energy phenomenon, WWC is in competition with conservative RLOF (i.e. mass transfer to the secondary star), and therefore has to be taken into account in this context.

Schnurr, Olivier; St-Louis, Nicole; Moffat, Anthony F. J.; Foellmi, Cedric

2002-08-01

343

WNL Stars - the Most Massive Stars in the Universe?  

NASA Astrophysics Data System (ADS)

We propose to carry out an intensive and complete time-dependent spectroscopic study of all 47 known WNL stars in the LMC, an ideal laboratory to study the effect of lower ambient metallicity, Z, on stellar evolution. WNL stars are luminous, cooler WR stars of the nitrogen sequence. This will allow us to: 1) determine the binary frequency. The Roche-lobe overflow (RLOF) mechanism in close binaries is predicted to be responsible for the formation of a significant fraction of WR stars in low Z environments such as the LMC. 2) determine the masses. Since some of these stars (denoted WNL(h) or WNLh) are supposed to be hydrogen-burning and thus main-sequence stellar objects of the highest luminosity, they may be the most massive stars known. 3) study wind-wind collision (WWC) effects in WR+O binaries involving very luminous WNL stars with strong winds. Interesting in itself as a high-energy phenomenon, WWC is in competition with conservative RLOF (i.e. mass transfer to the secondary star), and therefore has to be taken into account in this context.

Schnurr, Olivier; Moffat, Anthony F. J.; St-Louis, Nicole; Skalkowski, Gwenael; Niemela, Virpi; Shara, Michael M.

2001-08-01

344

Combinations of 148 Navigation Stars and the Star Tracker.  

National Technical Information Service (NTIS)

The angular separation of all star combinations for 148 nav star on the onboard software for space transportation system-3 flight and following missions is presented as well as the separation of each pair that satisfies the viewing constraints of using bo...

R. Duncan

1980-01-01

345

Star-forming galaxy models: Blending star formation into TREESPH  

NASA Astrophysics Data System (ADS)

We have incorporated star-formation algorithms into a hybrid N-body/smoothed particle hydrodynamics code (TREESPH) in order to describe the star forming properties of disk galaxies over timescales of a few billion years. The models employ a Schmidt law of index n approximately 1.5 to calculate star-formation rates, and explicitly include the energy and metallicity feedback into the Interstellar Medium (ISM). Modeling the newly formed stellar population is achieved through the use of hybrid SPH/young star particles which gradually convert from gaseous to collisionless particles, avoiding the computational difficulties involved in creating new particles. The models are shown to reproduce well the star-forming properties of disk galaxies, such as the morphology, rate of star formation, and evolution of the global star-formation rate and disk gas content. As an example of the technique, we model an encounter between a disk galaxy and a small companion which gives rise to a ring galaxy reminiscent of the Cartwheel (AM 0035-35). The primary galaxy in this encounter experiences two phases of star forming activity: an initial period during the expansion of the ring, and a delayed phase as shocked material in the ring falls back into the central regions.

Mihos, J. Christopher; Hernquist, Lars

1994-12-01

346

The Death of Stars II: High Mass Stars  

NSDL National Science Digital Library

This article from the Australian Telescope National Facility describes the death of massive stars. It discusses the formation and characteristics of supernovae, hypernovae, neutron stars/pulsars, and black holes. The article includes an animated diagram showing how the pulsar beam is observed from Earth.

2009-06-03

347

Stars with Extended Atmospheres  

NASA Astrophysics Data System (ADS)

This Workshop consisted of a full-day meeting of the Working Group "Sterren met Uitgebreide Atmosferen" (SUA, Working Group Stars with Extended Atmospheres), a discussion group founded in 1979 by Kees de Jager, Karel van der Hucht and Pik Sin The. This loose association of astronomers and astronomy students working in the Dutch-speaking part of the Low Countries (The Netherlands and Flanders) organised at regular intervals one-day meetings at the Universities of Utrecht, Leiden, Amsterdam and Brussels. These meetings consisted of the presentation of scientific results by junior as well as senior members of the group, and by discussions between the participants. As such, the SUA meetings became a forum for the exchange of ideas, and for asking questions and advice in an informal atmosphere. Kees de Jager has been chairman of the WG SUA from the beginning in 1979 till today, as the leading source of inspiration. At the occasion of Prof. Kees de Jager's 80th birthday, we decided to collect the presented talks in written form as a Festschrift in honour of this well-respected and much beloved scientist, teacher and friend. The first three papers deal with the personality of Kees de Jager, more specifically with his role as a supervisor and mentor of young researchers and as a catalyst in the research work of his colleagues. And also about his remarkable role in the establishment of astronomy education and research at the University of Brussels. The next presentation is a very detailed review of solar research, a field in which Cees was prominently active for many years. Then follow several papers dealing with stars about which Kees is a true expert: massive stars and extended atmospheres.

Sterken, C.

2002-12-01

348

Physics of compact stars  

NASA Astrophysics Data System (ADS)

This thesis starts with a pedagogical introduction to the study of white dwarfs and neutron stars. We will present a step-by-step study of compact stars in hydrostatic equilibrium leading to the equations of stellar structure. Through the use of a simple finite-difference algorithm, solutions to the equations for stellar structure both for white dwarfs and neutron stars are presented. While doing so, we will also introduce the physics of the equation of state and insights on dealing with units and rescaling the equations. The next project consists of the development of a "semi-classical" model to describe the equation of state of neutron-rich matter in the "Coulomb frustrated" phase known as nuclear pasta. In recent simulations we have resorted to a classical model that, while simple, captures the essential physics of the nuclear pasta, which consists of the interplay between long range Coulomb repulsion and short range nuclear attraction. However, for the nuclear pasta the de Broglie wavelength is comparable to the average inter- particle separation. Therefore, fermionic correlations are expected to become important. In an effort to address this challenge, a fictitious "Pauli potential" is introduced to mimic the fermionic correlations. In this thesis we will examine two issues. First, we will address some of the inherent difficulties in a widely used version of the Pauli potential. Second, we will refine the potential in a manner consistent with the most basic properties of a degenerate free Fermi gas, such as its momentum distribution and its two-body correlation function. With the newly refined potential, we study various physical observables, such as the two-body correlation function via Metropolis Monte-Carlo simulations.

Taruna, Jutri

2008-10-01

349

Variations in surface roughness of seven orthodontic archwires: an SEM-profilometry study  

PubMed Central

Objective The purpose of this study was to evaluate the surface roughness (SR) of 2 types of orthodontic archwires made by 4 different manufacturers. Methods This in vitro experimental study was conducted on 35 specimens of 7 different orthodontic archwires, namely, 1 nickel-titanium (NiTi) archwire each from the manufacturers American Orthodontics, OrthoTechnology, All-Star Orthodontics, and Smart Technology, and 1 stainless steel (SS) archwire each from the manufacturers American Orthodontics, OrthoTechnology, and All-Star Orthodontics. After analyzing the composition of each wire by energy-dispersive X-ray analysis, the SR of each wire was determined by scanning electron microscopy (SEM) and surface profilometry. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests (? < 0.05). Results The average SR of NiTi wires manufactured by Smart Technology, American Orthodontics, OrthoTechnology, and All-Star Orthodontics were 1,289 ± 915 A°, 1,378 ± 372 A°, 2,444 ± 369 A°, and 5,242 ± 2,832 A°, respectively. The average SR of SS wires manufactured by All-Star Orthodontics, OrthoTechnology, and American Orthodontics were 710 ± 210 A°, 1,831 ± 1,156 A°, and 4,018 ± 2,214 A°, respectively. Similar to the results of profilometry, the SEM images showed more defects and cracks on the SS wire made by American Orthodontics and the NiTi wire made by All-Star Orthodontics than others. Conclusions The NiTi wire manufactured by All-Star Orthodontics and the SS wire made by American Orthodontics were the roughest wires.

Rakhshan, Vahid; Pousti, Maryam; Rahimi, Hajir; Shariati, Mahsa; Aghamohamadi, Bahareh

2012-01-01

350

SCQGP in quark stars  

NASA Astrophysics Data System (ADS)

From an analogy with non-relativistic degenerate QED plasma we make an estimate of the coupling strength of QGP hypothesized to be present in compact star interiors. At densities ranging from 3 ? 0-10 ? 0 (normal nuclear density ? 0=0.16 fm-3), quark matter is found to be strongly to intermediately coupled. The equation of state for QED plasma obtained via Pade approximation, modified to QGP, yields stable stellar sequences with maximum mass ?2 M ? for B 1/4?215 MeV.

Ramadas, Sineeba; Bannur, Vishnu M.

2012-04-01

351

Star Atlases and Software  

NASA Astrophysics Data System (ADS)

In the 7 years or so that have passed since the first edition of this book was published perhaps one of the areas that has changed the most has been in the area of charts and software. The realm of the paper chart has pretty much been taken over by software in all its guises. It would perhaps not have been possible to have foreseen 10 years ago that one could look up double stars and their information on your phone as you can do on many of today's smart phones. The popularity of tablets and netbooks also means that much more information is now available in the field that it was before.

Brazell, Owen; Argyle, R. W.

352

Al-Sufi's Investigation of Stars, Star Clusters and Nebulae  

NASA Astrophysics Data System (ADS)

The distinguished Arabic astronomer, Al-Sufi (AD 903-986) is justly famous for his Book of the Fixed Stars, an outstanding Medieval treatise on astronomy that was assembled in 964. Developed from Ptolemy's Algamest, but based upon al-Sufi's own stellar observations, the Book of the Fixed Stars has been copied down through the ages, and currently 35 copies are known to exist in various archival repositories around the world. Among other things, this major work contains 55 astronomical tables, plus star charts for 48 constellations. For the first time a long-overdue English translation of this important early work is in active preparation. In this paper we provide biographical material about Al-Sufi and the contents of his Book of the Fixed Stars, before examining his novel stellar magnitude system, and his listing of star clusters and nebulae (including the first-ever mention of the Great Nebula in Andromeda).

Hafez, Ihsan; Stephenson, F. R.; Orchiston, W.

2011-01-01

353

The Dependence of Signal-To-Noise Ratio (S/N) Between Star Brightness and Background on the Filter Used in Images Taken by the Vulcan Photometric Planet Search Camera  

NASA Astrophysics Data System (ADS)

The Vulcan Photometric Planet Search is the ground-based counterpart of Kepler Mission Proposal. The Kepler Proposal calls for the launch of telescope to look intently at a small patch of sky for four year. The mission is designed to look for extra-solar planets that transit sun-like stars. The Kepler Mission should be able to detect Earth-size planets. This goal requires an instrument and software capable of detecting photometric changes of several parts per hundred thousand in the flux of a star. The goal also requires the continuous monitoring of about a hundred thousand stars. The Kepler Mission is a NASA Discovery Class proposal similar in cost to the Lunar Prospector. The Vulcan Search is also a NASA project but based at Lick Observatory. A small wide-field telescope monitors various star fields successively during the year. Dozens of images, each containing tens of thousands of stars, are taken any night that weather permits. The images are then monitored for photometric changes of the order of one part in a thousand. These changes would reveal the transit of an inner-orbit Jupiter-size planet similar to those discovered recently in spectroscopic searches. In order to achieve a one part in one thousand photometric precision even the choice of a filter used in taking an exposure can be critical. The ultimate purpose of an filter is to increase the signal-to-noise ratio (S/N) of one's observation. Ideally, filters reduce the sky glow cause by street lights and, thereby, make the star images more distinct. The higher the S/N, the higher is the chance to observe a transit signal that indicates the presence of a new planet. It is, therefore, important to select the filter that maximizes the S/N.

Mena-Werth, Jose

1998-10-01

354

Fate of most massive stars  

NASA Astrophysics Data System (ADS)

The first generations of stars are thought to have been more massive than Pop I stars and therefore some of these are thought to have produced pair creation supernovae (PCSNe) at the end of their life. However, the chemical signature of PCSNe is not observed in extremely metal poor stars (e.g. Umeda and Nomoto 2002) and it raises the following questions: Were stars born less (or more massive) than the mass range expected to lead to the PCSNe? Or was mass loss too strong during the evolution of these stars and prevented them from retaining enough mass to produce PCSNe? The discovery of very massive stars (VMS, M > 100 M ?) in the Milky Way and LMC (Crowther et al. 2010) shows that VMS can form and exist. The observations of PCSN candidates (2006gy & 2007bi) also seems to indicate that such SNe may occur. Mass loss plays a crucial role in the life of VMS since the star will only die as a PCSN if the star retains a high mass throughout its life. In this paper, we shall describe the dependence of VMS evolution on metallicity and present stellar evolution models at various metallicities, including the effects of mass loss and rotation. Based on our models, we will give our predictions concerning the fate of these VMS, either a PCSN or SNIc (possibly GRBs in some cases) as a function of metallicity.

Yusof, Norhasliza; Hirschi, Raphael; Kassim, Hasan Abu

2012-09-01

355

KAON CONDENSATION IN NEUTRON STARS.  

SciTech Connect

We discuss the kaon-nucleon interaction and its consequences for the change of the properties of the kaon in the medium. The onset of kaon condensation in neutron stars under various scenarios as well its effects for neutron star properties are reviewed.

RAMOS,A.; SCHAFFNER-BIELICH,J.; WAMBACH,J.

2001-04-24

356

On observing neutron star oscillations  

Microsoft Academic Search

To investigate detecting and identifying neutron star oscillations in x ray sources, a technique for computing the light curves produced from polar cap hotspots on rotating, oscillating neutron stars is developed. The calculations include the effects of general relativity on the photon trajectories and allow for anisotropic beaming of radiation from the polar caps. A simple model, based on stellar

Tod E. Strohmayer

1992-01-01

357

Radio emission from WR stars  

Microsoft Academic Search

It is pointed out that in principle radio observations of WR stars offer the best possibility of determining the rate of mass loss, since for a simple model of the extended atmosphere the mass loss rate depends primarily on quantities which are observable. Until now, detections of Wolf-Rayet stars have been limited by the sensitivity and resolution of available telescopes.

D. E. Hogg

1982-01-01

358

The Spectral Types of Stars  

NSDL National Science Digital Library

This article outlines the discovery of spectra and stellar spectral classifications. Included are mnemonics of the spectral sequence, what spectra lines can tell astronomers about a star, how temperature and luminosity relate to the Hertzsprung-Russell diagram, and luminosity classifications for stars.

Macrobert, Alan

2004-07-14

359

H? observations of Be stars  

NASA Astrophysics Data System (ADS)

We present here the H? spectra of 44 Be stars taken at a resolution of 0.5 Å. From the spectra, different emission line parameters have been deduced. A study of the correlations between different pairs of these parameters has been made with a view to understanding the mechanisms of line formation and shaping in Be stars.

Banerjee, D. P. K.; Rawat, S. D.; Janardhan, P.

2000-12-01

360

Distortion model for star tracker  

Microsoft Academic Search

In order to provide the beneficial expression of lens distortion for star trackers, the numerical results of the grid distortions of four typical star tracker lens systems have been investigated, and then data fitting is done with combined multinomial of different number of terms and powers of radial radius. The results indicate that the expression of relative distortion including terms

Hai-Bo Liu; Yi-Zhou Tan; Ding-Yi Sheng; Jian-Kun Yang; Ji-Chun Tan; Weng-Liang Wang; De-Zhi Su

2010-01-01

361

Dust near luminous ultraviolet stars  

NASA Astrophysics Data System (ADS)

This report describes research activities related to the Infrared Astronomical Satellite (IRAS) sky survey. About 745 luminous stars were examined for the presence of interstellar dust heated by a nearby star. The 'cirrus' discovered by IRAS is thermal radiation from interstellar dust at moderate and high galactic latitudes. The IRAS locates the dust which must (at some level) scatter ultraviolet starlight, although it was expected that thermal emission would be found around virtually every star, most stars shown no detectable emission. And the emission found is not uniform. It is not that the star is embedded in 'an interstellar medium', but rather what is found are discrete clouds that are heated by starlight. An exception is the dearth of clouds near the very hottest stars, implying that the very hottest stars play an active role with respect to destroying or substantially modifying the dust clouds over time. The other possibility is simply that the hottest stars are located in regions lacking in dust, which is counter-intuitive. A bibliography of related journal articles is attached.

Henry, Richard C.

1993-09-01

362

Photometric variability of magnetic stars  

Microsoft Academic Search

An analytic expression for the radiative flux from Ap stars is derived which can account for observational data that strongly suggest an inhomogeneous distribution of chemical elements on the stellar surface. The radiative flux from the visible hemisphere of a star is calculated as a function of the angle of inclination of the magnetic axis with respect to the rotational

F. A. Catalano

1975-01-01

363

Star formation in the multiverse  

SciTech Connect

We develop a simple semianalytic model of the star formation rate as a function of time. We estimate the star formation rate for a wide range of values of the cosmological constant, spatial curvature, and primordial density contrast. Our model can predict such parameters in the multiverse, if the underlying theory landscape and the cosmological measure are known.

Bousso, Raphael; Leichenauer, Stefan [Center for Theoretical Physics, Department of Physics, University of California, Berkeley, California 94720-7300 (United States) and Lawrence Berkeley National Laboratory, Berkeley, California 94720-8162 (United States)

2009-03-15

364

Recent star formation in galaxies  

Microsoft Academic Search

In recent years the study of starburst galaxies has become a very popular subject because of their intimate connection with the global star formation history of the Universe. Current estimates of the star formation rate of the Unvierse have been interpreted on the basis of our understanding of local analogous galaxies, in particular through UV continuum and optical line emission.

Alessandro Bressan

2002-01-01

365

White Dwarf Stars  

NASA Astrophysics Data System (ADS)

White dwarfs are the final stage for more than 95% of all stars. Their population statistics and properties contain a wealth of information about the history of star formation in our galaxy, the ages of stellar systems, and the relation between original mass at birth and that of the final remnant. They are also interesting individually as laboratories for physical conditions not easily reached in terrestrial labs: macroscopic manifestation of the Pauli principle, high densities and pressures, and extremely high magnetic fields. After a brief introduction with some historical milestones the observational status is reviewed: spectroscopic classification, determination of stellar parameters from spectroscopic and photometric observations, effective temperatures, surface gravities, radii, and masses. The next sections deal with the physics of the interior and evolution of white dwarfs, leading to the mass-radius relation and cooling times. Going back closer to the observations again, the physical processes in the outer layers are discussed: gravitational separation, diffusion, radiative levitation, accretion, and convective mixing. This leads to a review of our current understanding of the origin of spectral types and their interrelation. A final section gives brief introductions to topics at the center of current research: white dwarfs in open and globular clusters, debris disks, the origin of accreted metals in the atmospheres, magnetic fields and their origin, variable white dwarfs, and white dwarfs in binaries. This chapter was finished in February 2010 and reflects the status of knowledge at that time.

Koester, Detlev

366

Really Hot Stars  

NASA Astrophysics Data System (ADS)

Spectacular VLT Photos Unveil Mysterious Nebulae Summary Quite a few of the most beautiful objects in the Universe are still shrouded in mystery. Even though most of the nebulae of gas and dust in our vicinity are now rather well understood, there are some which continue to puzzle astronomers. This is the case of a small number of unusual nebulae that appear to be the subject of strong heating - in astronomical terminology, they present an amazingly "high degree of excitation". This is because they contain significant amounts of ions, i.e., atoms that have lost one or more of their electrons. Depending on the atoms involved and the number of electrons lost, this process bears witness to the strength of the radiation or to the impact of energetic particles. But what are the sources of that excitation? Could it be energetic stars or perhaps some kind of exotic objects inside these nebulae? How do these peculiar objects fit into the current picture of universal evolution? New observations of a number of such unusual nebulae have recently been obtained with the Very Large Telescope (VLT) at the ESO Paranal Observatory (Chile). In a dedicated search for the origin of their individual characteristics, a team of astronomers - mostly from the Institute of Astrophysics & Geophysics in Liège (Belgium) [1] - have secured the first detailed, highly revealing images of four highly ionized nebulae in the Magellanic Clouds, two small satellite galaxies of our home galaxy, the Milky Way, only a few hundred thousand light-years away. In three nebulae, they succeeded in identifying the sources of energetic radiation and to eludicate their exceptional properties: some of the hottest, most massive stars ever seen, some of which are double. With masses of more than 20 times that of the Sun and surface temperatures above 90 000 degrees, these stars are truly extreme. PR Photo 09a/03: Nebula around the hot star AB7 in the SMC. PR Photo 09b/03: Nebula near the hot Wolf-Rayet star BAT99-2 in the LMC. PR Photo 09c/03: Nebula near the hot binary star BAT99-49 in the LMC. PR Photo 09d/03: The N44C Nebula in the LMC. Four unique images of highly excited nebulae in the Magellanic Clouds ESO PR Photo 09a/03 ESO PR Photo 09a/03 [Preview - JPEG: 400 x 472 pix - 74k [Normal - JPEG: 800 x 943 pix - 720k] [Full-Res - JPEG: 1200 x 1414 pix - 1.2M] ESO PR Photo 09b/03 ESO PR Photo 09b/03 [Preview - JPEG: 400 x 466 pix - 70k [Normal - JPEG: 800 x 931 pix - 928k] [Full-Res - JPEG: 1200 x 1397 pix - 1.8M] ESO PR Photo 09c/03 ESO PR Photo 09c/03 [Preview - JPEG: 400 x 469 pix - 74k [Normal - JPEG: 800 x 937 pix - 1.1M] [Full-Res - JPEG: 1200 x 1405 pix - 2.2M] ESO PR Photo 09d/03 ESO PR Photo 09d/03 [Preview - JPEG: 400 x 473 pix - 28k [Normal - JPEG: 800 x 945 pix - 368k] [Full-Res - JPEG: 1200 x 1418 pix - 600k] Captions: PR Photo 09a/03 is a reproduction of a "near-true" three-colour composite image of the highly excited nebula around the hot double star AB7 in the Small Magellanic Cloud (SMC), obtained in January 2002 with the FORS1 multi-mode instrument at the 8.2-m VLT MELIPAL telescope at the Paranal Observatory (Chile). It is based on three exposures through narrow-band optical (interference) filters that isolate the light from specific atoms and ions. In this rendering, the blue colour represents the light from singly ionized Helium (He II; wavelength 468.6 nm; exposure time 30 min), green corresponds to doubly ionized oxygen ([O III]; 495.7 + 500.7 nm; 5 min) and red to hydrogen atoms (H; H-alpha line at 656.2 nm; 5 min). Of these three ions, He II is the tracer of high excitation, i.e. the bluest areas of the nebula are the hottest. The sky field measures 400 x 400 arcsec2; the original pixel size on the 2k x 2k CCD is 0.23 arcsec. North is up and east to the left. Before combination, the CCD frames were flat-fielded and cleaned of cosmic-rays. Moreover, the stars in the blue (He II) image were removed in order to provide a clearer view of the surrounding nebular emission. The reproduced brightness is proportional to the squar

2003-04-01

367

The Stars of Heaven  

NASA Astrophysics Data System (ADS)

Do a little armchair space travel, rub elbows with alien life forms, and stretch your mind to the furthest corners of our uncharted universe. With this astonishing guidebook, you don't have to be an astronomer to explore the mysteries of stars and their profound meaning for human existence. Clifford A. Pickover tackles a range of topics from stellar evolution to the fundamental reasons why the universe permits life to flourish. He alternates sections that explain the mysteries of the cosmos with sections that dramatize mind-expanding concepts through a fictional dialog between futuristic humans and their alien peers (who embark on a journey beyond the reader's wildest imagination). This highly accessible and entertaining approach turns an intimidating subject into a scientific game open to all dreamers. Told in Pickover's inimitable blend of fascinating state-of-the-art science and whimsical science fiction, and packed with numerous diagrams and illustrations, The Stars of Heaven unfolds a world of paradox and mystery, one that will intrigue anyone who has ever pondered the night sky with wonder.

Pickover, Clifford A.

2004-05-01

368

Photometric Observations of 6000 Stars in the Cygnus Field.  

National Technical Information Service (NTIS)

A small photometer to detect transits by extrasolar planets has been assembled and is being tested at Lick Observatory on Mt. Hamilton, California. The Vulcan photometer is constructed from a 30 cm focal length, F/2.5 AeroEktar reconnaissance lens and Pho...

W. Borucki D. Caldwell D. Koch J. Jenkins Z. Ninkov

1999-01-01

369

Relativistic Strange Stars with Anisotropy  

NASA Astrophysics Data System (ADS)

We study a compact star comprising strange matter content in the presence of pressure anisotropy. Considering strange matter with equation of state p = (?-4B)/3, where B is Bag parameter, we analyze the effect of pressure anisotropy on the Bag parameter for a compact star described by Vaidya-Tikekar metric. The values of B inside and on surface of the star are determined for different anisotropy parameter ?. It is found that in the vicinity of the center of a compact star, B parameter is almost constant. However, away from the center B varies with the radial distance and finally at the surface B attains a value independent of the anisotropy. It is also noted that for some values of ?, B remains constant throughout the star. Given ? and spheriodicity a, B is found to be decreasing with the increase in compactness factor. The models admitting B increasing with ? for a given spheriodicity parameter (a) and compactness are also found.

Paul, B. C.; Chattopadhyay, P. K.; Karmakar, S.; Tikekar, R.

370

FLARES ON A Bp STAR  

SciTech Connect

Two large X-ray flares have been reported from the direction of a magnetic B2p star ({sigma} Ori E). Sanz-Forcada et al. have suggested that the flares did not occur on the B2p star but on a companion of late spectral type. A star which is a candidate for a late-type flare star near {sigma} Ori E has recently been identified by Bouy et al. However, based on the properties of the flares, and based on a recent model of rotating magnetospheres, we argue that, rather than attributing the two flares to a late-type dwarf, it is a viable hypothesis that the flares were magnetic phenomena associated with the rotating magnetosphere of the B2p star itself.

Mullan, D. J. [Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States)

2009-09-01

371

Bag model and quark star  

NASA Astrophysics Data System (ADS)

In this paper, incorporating the property of the vacuum negative pressure, namely, the bag constant, we present a new model of the equation of state (EOS) of quark matter at finite chemical potential and zero temperature. By comparing our EOS with Fraga et al.’s EOS and SQM1 model, one finds that our EOS is softer than Fraga et al.’s EOS and SQM1 model. The reason for this difference is analyzed. With these results we investigate the structure of a quark star. A comparison between our model of the quark star and other models is made. The obtained mass of the quark star is 1.3˜1.66M? and the radius is 9.5˜14Km. One can see that our star’s compactness is smaller than that of the other two models.

Li, Hua; Luo, Xin-Lian; Zong, Hong-Shi

2010-09-01

372

Infant stars at feeding time  

NASA Astrophysics Data System (ADS)

Astronomers have used ESO's Very Large Telescope Interferometer to conduct the first high resolution survey that combines spectroscopy and interferometry on intermediate-mass infant stars. They obtained a very precise view of the processes acting in the discs that feed stars as they form. These mechanisms include material infalling onto the star as well as gas being ejected, probably as a wind from the disc. Disc around young star ESO PR Photo 35/08 Disc Around Young Star Infant stars form from a disc of gas and dust that surrounds the new star and, later, may also provide the material for a planetary system. Because the closest star-forming regions to us are about 500 light-years away, these discs appear very small on the sky, and their study requires special techniques to be able to probe the finer details. This is best done with interferometry, a technique that combines the light of two or more telescopes so that the level of detail revealed corresponds to that which would be seen by a telescope with a diameter equal to the separation between the interferometer elements, typically 40 to 200 metres. ESO's Very Large Telescope Interferometer (VLTI) has allowed astronomers to reach a resolution of about a milli-arcsecond, an angle equivalent to the size of the full stop at the end of this sentence seen from a distance of about 50 kilometres. "So far interferometry has mostly been used to probe the dust that closely surrounds young stars," says Eric Tatulli from Grenoble (France), who co-led this international project. "But dust is only one percent of the total mass of the discs. Their main component is gas, and its distribution may define the final architecture of planetary systems that are still forming." The ability of the VLTI and the AMBER instrument to take spectra while probing objects at milli-arcsecond resolution has allowed astronomers to map the gas. Astronomers studied the inner gaseous environments of six young stars belonging to the family of Herbig Ae/Be objects. These objects have masses a few times that of our Sun and are still forming, increasing in mass by swallowing material from the surrounding disc. The team used these observations to show that gas emission processes can be used to trace the physical processes acting close to the star. "The origin of gas emissions from these young stars has been under debate until now, because in most earlier investigations of the gas component, the spatial resolution was not high enough to study the distribution of the gas close to the star," says co-leader Stefan Kraus from Bonn in Germany. "Astronomers had very different ideas about the physical processes that have been traced by the gas. By combining spectroscopy and interferometry, the VLTI has given us the opportunity to distinguish between the physical mechanisms responsible for the observed gas emission." Astronomers have found evidence for matter falling into the star for two cases, and for mass outflow in four other stars, either in an extended stellar wind or in a disc wind. It also seems that, for one of the stars, dust may be present closer to the star than had been generally expected. The dust is so close that the temperature should be high enough for it to evaporate, but since this is not observed, it must mean that gas shields the dust from the star's light. These new observations demonstrate that it is now possible to study gas in the discs around young stars. This opens new perspectives for understanding this important phase in the life of a star. "Future observations using VLTI spectro-interferometry will allow us to determine both the spatial distribution and motion of the gas, and might reveal whether the observed line emission is caused by a jet launched from the disc or by a stellar wind", concludes Stefan Kraus.

2008-10-01

373

Grand unification of neutron stars  

PubMed Central

The last decade has shown us that the observational properties of neutron stars are remarkably diverse. From magnetars to rotating radio transients, from radio pulsars to isolated neutron stars, from central compact objects to millisecond pulsars, observational manifestations of neutron stars are surprisingly varied, with most properties totally unpredicted. The challenge is to establish an overarching physical theory of neutron stars and their birth properties that can explain this great diversity. Here I survey the disparate neutron stars classes, describe their properties, and highlight results made possible by the Chandra X-Ray Observatory, in celebration of its 10th anniversary. Finally, I describe the current status of efforts at physical “grand unification” of this wealth of observational phenomena, and comment on possibilities for Chandra’s next decade in this field.

Kaspi, Victoria M.

2010-01-01

374

The Nuclear Physics of Stars  

NASA Astrophysics Data System (ADS)

Atomic nuclei are at the core of all the matter around us and are the fuel of stars. Nuclear reactions produce the energy in our sun that enables live on our planet and nuclear processes during the live and death of stars produce most of the chemical elements in our world. The atomic nucleus in every atom and molecule in our bodies and the world around us is a remnant of the star in which it was produced. Thus in the most literal sense we are all star dust. Many aspects of the production of the chemical elements have been solved but many mysteries remain. In this talk I will summarize what we know about the production of the elements in stars and show how nuclear physics experiments carried out at TRIUMF, Canada's national laboratory for particle and nuclear physics in Vancouver, can help to answer the open questions in this quest for understanding the origins of the chemical elements.

Kruecken, Reiner

2012-10-01

375

Neutron stars, strange stars, and the nuclear equation of state  

SciTech Connect

This article consists of three parts. In part one we review the present status of dense nuclear matter calculations, and introduce a representative collection of realistic nuclear equations of state which are derived for different assumptions about the physical behavior of dense matter (baryon population, pion condensation,.possible transition of baryon matter to quark matter). In part two we review recently performed non-rotating and rotating compact star calculations performed for these equations of state. The minimum stable rotational periods of compact stars, whose knowledge is of decisive importance for the interpretation of rapidly rotating pulsars, axe determined. For this purpose two different limits on stable rotation are studied: rotation at the general relativistic Kepler period (below which mass shedding at the star`s equator sets in), and, secondly, rotation at the gravitational radiation-reaction instability (at which emission of gravitational waves set in which slows the star down). Part three of this article deals with the properties of hypothetical strange stars. Specifically we investigate the amount of nuclear solid crust that can be carried by a rotating strange star, and answer the question whether such objects can give rise to the observed phenomena of pulsar glitches, which is at the present time the only astrophysical test of the strange-quark-matter hypothesis.

Weber, F.; Glendenning, N.K.

1992-11-02

376

Populations of Be stars: stellar evolution of extreme stars  

NASA Astrophysics Data System (ADS)

Among the emission-line stars, the classical Be stars known for their extreme properties are remarkable. The Be stars are B-type main sequence stars that have displayed at least once in their life emission lines in their spectrum. Beyond this phenomenological approach some progresses were made on the understanding of this class of stars. With high-technology techniques (interferometry, adaptive optics, multi-objects spectroscopy, spectropolarimetry, high-resolution photometry, etc) from different instruments and space mission such as the VLTI, CHARA, FLAMES, ESPADONS-NARVAL, COROT, MOST, SPITZER, etc, some discoveries were performed allowing to constrain the modeling of the Be stars stellar evolution but also their circumstellar decretion disks. In particular, the confrontation between theory and observations about the effects of the stellar formation and evolution on the main sequence, the metallicity, the magnetic fields, the stellar pulsations, the rotational velocity, and the binarity (including the X-rays binaries) on the Be phenomenon appearance is discussed. The disks observations and the efforts made on their modeling is mentioned. As the life of a star does not finish at the end of the main sequence, we also mention their stellar evolution post main sequence including the gamma-ray bursts. Finally, the different new results and remaining questions about the main physical properties of the Be stars are summarized and possible ways of investigations proposed. The recent and future facilities (XSHOOTER, ALMA, E-ELT, TMT, GMT, JWST, GAIA, etc) and their instruments that may help to improve the knowledge of Be stars are also briefly introduced.

Martayan, Christophe; Rivinius, Thomas; Baade, Dietrich; Hubert, Anne-Marie; Zorec, Jean

2011-07-01

377

StarGuides Plus  

NASA Astrophysics Data System (ADS)

StarGuides Plus represents the most comprehensive and accurately validated collection of practical data on organizations involved in astronomy, related space sciences and other related fields. This invaluable reference source (and its companion volume, StarBriefs Plus) should be on the reference shelf of every library, organization or individual with any interest in these areas. The coverage includes relevant universities, scientific committees, institutions, associations, societies, agencies, companies, bibliographic services, data centers, museums, dealers, distributors, funding organizations, journals, manufacturers, meteorological services, national norms & standard institutes, parent associations & societies, publishers, software producers & distributors, and so on. Besides astronomy and associated space sciences, related fields such as aeronautics, aeronomy, astronautics, atmospheric sciences, chemistry, communications, computer sciences, data processing, education, electronics, engineering, energetics, environment, geodesy, geophysics, information handling, management, mathematics, meteorology, optics, physics, remote sensing, and so on, are also covered where appropriate. After some thirty years in continuous compilation, verification and updating, StarGuides Plus currently gathers together some 6,000 entries from 100 countries. The information is presented in a clear, uncluttered manner for direct and easy use. For each entry, all practical data are listed: city, postal and electronic-mail addresses, telephone and fax numbers, URLs for WWW access, foundation years, numbers of members and/or numbers of staff, main activities, publications titles (with frequencies, ISS-Numbers and circulations), names and geographical coordinates of observing sites, names of planetariums, awards (prizes and/or distinctions) granted, etc. The entries are listed alphabetically in each country. An exhaustive index gives a breakdown not only by different designations and acronyms, but also by location and major terms in names. Thematic sub-indices are also provided as well as a list of telephone and telefax national codes. In short, almost anyone involved in any way in the fields of astronomy and related space sciences will find invaluable contact and background information in this volume. All entries have been compiled from data supplied by the listed organizations and all data have been independently verified - making this compilation the most accurate and relevant source available. Link: http://www.wkap.nl/prod/b/1-4020-1926-2

Heck, A.

378

Zenith Star Launch System  

NASA Astrophysics Data System (ADS)

The Zenith Star Launch System (ZSLS) will be used by the SDIO to loft the Alpha Laser and its Large Adaptive Mirror system to orbit. ZSLS performance requirements were rendered especially severe by the weights of these systems, which involved not only the 40,000 lbs of the laser and 15,000 lbs of the mirror, but the weight of laser fuel, laser coolant, beam-control system, target acquisition system, and laser pointing/tracking system. The Titan IV launch vehicle could not have lifted more than 40,000 lbs to LEO. The requisite 100,000 lbs will instead be boosted by a composite launch vehicle consisting of three Shuttle SRBs surrounding a cluster of six Delta II liquid-propellant first stages, and an air-started Delta II first stage. The payload fits within a Titan IV fairing.

Stafford, Larry; Rendine, Michael J.

1990-09-01

379

GENERAL: Double Degenerate Stars  

NASA Astrophysics Data System (ADS)

Regardless of the formation mechanism, an exotic object, the double degenerate star (DDS), is introduced and investigated, which is composed of baryonic matter and some unknown fermion dark matter. Different from the simple white dwarfs (WDs), there is additional gravitational force provided by the unknown fermion component inside DDSs, which may strongly affect the structure and the stability of such kind of objects. Many possible and strange observational phenomena connecting with them are concisely discussed. Similar to the normal WD, this object can also experience thermonuclear explosion as type Ia supernova explosion when DDS's mass exceeds the maximum mass that can be supported by electron degeneracy pressure. However, since the total mass of baryonic matter can be much lower than that of WD at Chandrasekhar mass limit, the peak luminosity should be much dimmer than what we expect before, which may throw a slight shadow on the standard candle of SN Ia in the research of cosmology.

Luo, Xin-Lian; Bai, Hua; Zhao, Lei

2008-07-01

380

Star in the making  

SciTech Connect

As the result of a recent series of high-frequency molecular-line observations, astronomers may have detected the infalling envelope around an embedded radiation source, providing the first direct glimpse at the actual process of star formation. The object in question is known as IRAS 16293-2422 and was initially uncovered in a sky survey by the Infrared Astronomical Satellite. It is in an outlying region of the Ophiuchus dark nebula, near rho Ophiuchi just north of Antares, about 520 light-years away. Using the 12-m-diameter radio telescope of the National Radio Astronomy Observatory at Kitt Peak, emissions from a spectral line of the carbon monosulfide molecule (CS) were observed at a frequency near 245,000 MHz, corresponding to a wavelength of about 1 mm; the asymmetric shape of the emission curve is just what would be expected from a collapsing gas.

Lada, C.J.

1986-10-01

381

Delayed star formation in galaxies  

SciTech Connect

The problem of delayed star formation in galaxies is formulated, and some possible approaches to solving it are discussed. Observational evidence suggests that galaxies undergo long periods (10/sup 8/--10/sup 10/ yr) when star formation is suppressed. Two modes of star formation are considered: 1) gravitational collapse and fragmentation of initially rarefied gas; 2) creation of stars through collisions of interstellar clouds. In these contexts three mechanisms are examined for suppressing star formation, each involving supernova outbursts: a) the gas density in the disk of a galaxy drops below its critical value; b) gravitationally bound fragments are disrupted through heating by external radiation sources (supernovae and supernova remnants); c) the cool interstellar gas phase decays when the heating rate rises above a critical value. Estimates of the heating rate indicate that star formation will be suppressed by mechanisms b and c. If the number of supernovae and supernova remnants was formerly one to three orders of magnitude greater than today, as could have happened in the Galaxy during active evolutionary phases, then star formation could indeed have been suppressed.

Suchkov, A.A.; Shchekinov, Y.A.

1979-11-01

382

Star Formation at z ~ 1  

NASA Astrophysics Data System (ADS)

We propose using FLAMINGOS in MOS mode to obtain near-infrared spectra of ~ 200 GOODS galaxies at z ~ 1, using the 4-m telescope on Kitt Peak. This will, for the first time, provide a sample of sufficient size to allow for a statistically sound analysis of the star formation rate at z ~ 1; a crucial epoch in the star formation history of the Universe. Several controversial issues will be addressed using this dataset. H(alpha), used routinely as a local star formation indicator, will be directly measured in order to determine the global star formation rate at z ~ 1, where many conflicting results exist. Star formation rates derived from the H(alpha) emission will also be used to calibrate star formation derived from existing MIPS 24 (mu) m data, equivalent at z ~ 1 to 12 (mu) m rest frame emission, which is caused by PAHs and warm, small-grain thermal continuum. Finally, star formation estimates from the most commonly used indicators, namely H(alpha), [OII], radio, UV and PAH features, will be compared and assessed. Line ratios from features in the FLAMINGOS near-IR and recently obtained Keck optical spectra will allow for the quantification of extinction and metallicity.

MacDonald, Emily; Dickinson, Mark; Mobasher, Bahram; Allen, Paul; Papovich, Casey

2006-02-01

383

Strange-quark-matter stars  

SciTech Connect

We investigate the implications of rapid rotation corresponding to the frequency of the new pulsar reported in the supernovae remnant SN1987A. It places very stringent conditions on the equation of state if the star is assumed to be bound by gravity alone. We find that the central energy density of the star must be greater than 13 times that of nuclear density to be stable against the most optimistic estimate of general relativistic instabilities. This is too high for the matter to consist of individual hadrons. We conclude that it is implausible that the newly discovered pulsar, if its half-millisecond signals are attributable to rotation, is a neutron star. We show that it can be a strange quark star, and that the entire family of strange stars can sustain high rotation if strange matter is stable at an energy density exceeding about 5.4 times that of nuclear matter. We discuss the conversion of a neutron star to strange star, the possible existence of a crust of heavy ions held in suspension by centrifugal and electric forces, the cooling and other features. 34 refs., 10 figs., 1 tab.

Glendenning, N.K.

1989-11-01

384

Different type of maser star  

SciTech Connect

A systematic survey of short-period, semiregular variable stars has been made resulting in the detection of six new water masers. Of the 14 short-period maser stars now known, nine are classified as SRb variables. All are very late spectral type SRb's typically M7, while the overwhelming majority of normal SRb stars is M4 to M6. Their (2.2 ..mu..)--(11 ..mu..) colar indices are among the lowest of any known maser stars. They are presumably less dusty as well. Four of the SRb stars and two of the remainder do not obey the correlation between period and velocity spread of the emission features that is found for the Mira and long-period, semiregular variables. Finally, high galactic latitudes dominate; 13 of the 14 are in excess of 13/sup 0/, and nine of these are greater than 25/sup 0/. These facts suggest that the short-period semiregular variables: particularly the SRb stars: may be a very different type of maser star than the Mira and long-period semiregular variables.

Dickinson, D.F.; Dinger, A.S.C.

1982-03-01

385

Long-term treatment with standardized extract of Ginkgo biloba L. enhances the conditioned suppression of licking in rats by the modulation of neuronal and glial cell function in the dorsal hippocampus and central amygdala.  

PubMed

Our group previously demonstrated that short-term treatment with a standardized extract of Ginkgo biloba (EGb) changed fear-conditioned memory by modulating gene expression in the hippocampus, amygdaloid complex and prefrontal cortex. Although there are few controlled studies that support the long-term use of EGb for the prevention and/or treatment of memory impairment, the chronic use of Ginkgo is common. This study evaluated the effects of chronic treatment with EGb on the conditioned emotional response, assessed by the suppression of ongoing behavior and in the modulation of gene and protein expression. Male adult Wistar rats were treated over 28days and assigned to five groups (n=10) as follows: positive control (4mgkg(-1) Diazepam), negative control (12% Tween 80), EGb groups (0.5 and 1.0gkg(-1)) and the naïve group. The suppression of the licking response was calculated for each rat in six trials. Our results provide further evidence for the efficacy of EGb on memory. For the first time, we show that long-term treatment with the highest dose of EGb improves the fear memory and suggests that increased cAMP-responsive element-binding protein (CREB)-1 and glial fibrillary acidic protein (GFAP) mRNA and protein (P<0.001) in the dorsal hippocampus and amygdaloid complex and reduced growth and plasticity-associated protein 43 (GAP-43) (P<0.01) in the hippocampus are involved in this process. The fear memory/treatment-dependent changes observed in our study suggest that EGb might be effective for memory enhancement through its effect on the dorsal hippocampus and amygdaloid complex. PMID:23321541

Oliveira, D R; Sanada, P F; Filho, A C S; Conceição, G M S; Cerutti, J M; Cerutti, S M

2013-01-12

386

Exoplanets bouncing between binary stars  

NASA Astrophysics Data System (ADS)

Exoplanetary systems are found not only among single stars, but also among binaries of widely varying parameters. Binaries with separations of 100-1000 au are prevalent in the solar neighbourhood; at these separations, planet formation around a binary member may largely proceed as if around a single star. During the early dynamical evolution of a planetary system, planet-planet scattering can eject planets from a star's grasp. In a binary, the motion of a planet ejected from one star has effectively entered a restricted three-body system consisting of itself and the two stars, and the equations of motion of the three-body problem will apply as long as the ejected planet remains far from the remaining planets. Depending on its energy, escape from the binary as a whole may be impossible or delayed until the three-body approximation breaks down, and further close interactions with its planetary siblings boost its energy when it passes close to its parent star. Until then, this planet may be able to transition from the space around one star to the other, and chaotically 'bounce' back and forth. In this paper, we directly simulate scattering planetary systems that are around one member of a circular binary, and quantify the frequency of bouncing in scattered planets. We find that a great majority (70-85 per cent) of ejected planets will pass at least once through the space of it's host's binary companion, and depending on the binary parameters about 35-75 per cent will begin bouncing. The time spent bouncing is roughly lognormally distributed with a peak at about 104 yr, with only a small percentage bouncing for more than 1 Myr. This process may perturb and possibly incite instability among existing planets around the companion star. In rare cases, the presence of multiple planets orbiting both stars may cause post-bouncing capture or planetary swapping.

Moeckel, Nickolas; Veras, Dimitri

2012-05-01

387

Do Massive Stars Have Planets?  

NASA Astrophysics Data System (ADS)

We recently conducted a near- and mid-infrared survey of a sample of 117 DA white dwarfs from the Palomar-Green (PG) survey. The white dwarfs in this sample are decedent from 1-7 solar mass stars; this survey constrained the frequency of planetary systems in the elusive intermediate-mass regime. We found that at least 4.3% of 1-7 Msol stars host planetary systems. However, the mass distribution of our sample is strongly biased toward lower mass white dwarfs, descendants of M < 3 Msol main-sequence stars. To constrain the frequency of dusty disks around massive white dwarfs, and in turn the frequency of planets around their massive progenitor main-sequence stars, we propose to observe 100 massive white dwarfs from the Sloan Digital Sky Survey in the IRAC 4.5 micron band. We restrict our sample to M > 0.8 Msol white dwarfs (> 3 Msol progenitor stars) and Teff = 9500 - 22,500 K. All but one of the known dusty white dwarfs have temperatures in this range, where dust orbiting within the tidal radius of the star will remain solid. However, no previous Spitzer survey has targeted massive WDs in this temperature range, and this unique discovery space remains unexplored. Assuming a similar disk frequency for normal and massive WDs, we are 99.5% confident that our proposed survey of 100 stars will find at least one dusty WD and it will provide stringent constraints on the frequency of planets around massive stars for the first time. This result will provide an important test for the planet formation models around sun-like and higher mass stars.

Barber, Sara; Kilic, Mukremin; Leggett, Sandy

2012-12-01

388

`Bare' Strange Stars Might Not Be Bare  

Microsoft Academic Search

It is proposed that the `bare' strange matter stars might not be bare, and the observed pulsars might be in fact the `bare' strange stars. As intensely magnetized strange matter stars rotate, the induced unipolar electric fields would be large enough to construct magnetospheres. This situation is very similar to that discussed by many authors for rotating neutron stars. Also,

Ren-xin Xu; Guo-jun Qiao

1998-01-01

389

Poly(ethylene glycol) Star Polymer Hydrogels  

Microsoft Academic Search

Poly(ethylene glycol) (PEG) star polymer hydrogels were prepared by Á-irradiation of aqueous solutions of star PEG polymers. The swelling behavior of these gels in deionized water at 37 °C indicated that the gels prepared from PEG star polymers with a small number of long arms swelled to a greater extent than those prepared from PEG star polymers with a large

Kelley Britton Keys; Fotios M. Andreopoulos; Nikolaos A. Peppas

1998-01-01

390

Delays of star formation in galaxies  

Microsoft Academic Search

Evidence for the extended supression of star formation in galaxies is reviewed, and possible mechanisms for these delays are examined. Observations of metallic abundances and kinetics of stars are presented as evidence for gaps of up to 10 billion years between periods of star formation in the Milky Way and other galaxies. Consideration is then given to models of star

A. A. Suchkov; Y. A. Shchekinov

1979-01-01

391

Controlling factors for global star formation  

Microsoft Academic Search

Here I attempt to address the question: What do we know, or can we know, about the controlling factors for global star formation? First, I open with a very brief review of measurements of current star formation rates. While absolute estimates of current star formation rates carry a significant degree of uncertainty, the comparison of current star formation rates has

Evan D. Skillman

1997-01-01

392

Bimodal Star Formation, Starbursts, and Galaxy Formation  

Microsoft Academic Search

A phenomenological approach is developed for studying star formation in the galactic disk, in starbursts, and in protogalaxies. The evidence is reviewed for bimodal star formation, and physical mechanisms are mentioned. A simple expression for the star formation rate in the disk is derived, and applied to estimate star formation time scales in the disk, in starbursts, and in protogalaxies.

Joseph Silk

1988-01-01

393

Insights from simulations of star formation  

Microsoft Academic Search

Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of nearly singular peaks in density, followed by the accretional growth of embryo stars that form at these density peaks. Circumstellar discs often form from the

Richard B Larson

2007-01-01

394

Star formation in colliding and merging galaxies  

Microsoft Academic Search

The process of star formation in interacting galaxies is discussed, reviewing the results of recent observational and theoretical investigations. Topics examined include the general characteristics of starburst galaxies, the spatial distribution of star formation, the mechanisms governing the formation of molecular gas, star-formation rates, star-formation efficiency, and initial mass functions. It is suggested that galactic collisions or mergers may lead

Francois Schweizer

1987-01-01

395

Star formation in active galaxies and quasars  

Microsoft Academic Search

The observationaal evidence for a causal or statistical link between star formation and active galactic nuclei are reviewed. The chief difficulty is in quantitatively ascertaining the star formation rate in active galaxies: most of the readily observable manifestations of star formation superficially resemble those of an active nucleus. Careful multi-wavelength spatially-resolved observations demonstrate that many Seyfert galaxies are undergoing star

Timothy M. Heckman

1987-01-01

396

A Heavy Flavor Tracker for STAR  

SciTech Connect

We propose to construct a Heavy Flavor Tracker (HFT) for the STAR experiment at RHIC. The HFT will bring new physics capabilities to STAR and it will significantly enhance the physics capabilities of the STAR detector at central rapidities. The HFT will ensure that STAR will be able to take heavy flavor data at all luminosities attainable throughout the proposed RHIC II era.

Xu, Z.; Chen, Y.; Kleinfelder, S.; Koohi, A.; Li, S.; Huang, H.; Tai, A.; Kushpil, V.; Sumbera, M.; Colledani, C.; Dulinski, W.; Himmi,A.; Hu, C.; Shabetai, A.; Szelezniak, M.; Valin, I.; Winter, M.; Surrow,B.; Van Nieuwenhuizen, G.; Bieser, F.; Gareus, R.; Greiner, L.; Lesser,F.; Matis, H.S.; Oldenburg, M.; Ritter, H.G.; Pierpoint, L.; Retiere, F.; Rose, A.; Schweda, K.; Sichtermann, E.; Thomas, J.H.; Wieman, H.; Yamamoto, E.; Kotov, I.

2005-03-14

397

Subluminous Wolf-Rayet stars - Observations  

Microsoft Academic Search

Even though the loss of the outer, H-rich envelope may be a necessary condition for forming WR stars, it is clearly not a sufficient one. This is because the majority of planetary nuclei do not have a WR-type spectrum. The question why some central stars are WR stars while others are, say, O stars is addressed here. The question is

S. R. Heap

1982-01-01

398

Where Are the Distant Worlds? Star Maps  

NSDL National Science Digital Library

This fun hands-on astronomy activity lets learners use star maps (included) to find constellations and to identify stars with extrasolar planets (Northern Hemisphere only, naked eye). Use this activity at a star party on a dark, clear night. Included in the PDF are activity suggestions, background information, and over 30 pages of printable star maps and planetary postcards.

Pacific, Astronomical S.

2009-01-01

399

Modeling of the Be Stars  

NASA Astrophysics Data System (ADS)

The Be stars are still a big unknown in respect to the origin and geometry of the circumstellar disk around the star. Program shellspec is designed to solve the simple radiative transfer along the line of sight in three-dimensional moving media. Our goal was to develop an effective method to search in parameter space, which can allow us to find a good estimate of the physical parameters of the disk. We also present here our results for Be star 60 Cyg using the modified code.

Šejnová, K.; Votruba, V.; Koubský, P.

2012-04-01

400

A Mystery of Space: Stars  

NSDL National Science Digital Library

This resource covers stars, the Sun, black holes, the Solar System, and cosmic phenomena. Users may choose between two different levels: one for kids 12 and under, and one for teachers and anyone over 13. The Galactic Glossary explains complicated space terms. There are six lesson plans, each of which encourage the Internet style of learning, and feature numerous hands-on activities. Three animated tutorials on supernovas, the life of a star, and the sun, offer students a fun way to learn about stars. The Gallery contains an art and picture post, a story and sighting post, a constellation myth post, and a constellation poll.

Masnick, Max; Schwartzman, Josh

1999-01-01

401

Sodium laser guide star system at Lawrence Livermore National Laboratory: System description and experimental results  

SciTech Connect

The architecture and major system components of the sodium-layer kw guide star system at LLNL will be described, and experimental results reported. The subsystems include the laser system, the beam delivery system including a pulse stretcher and beam pointing control, the beam director, and the telescope with its adaptive-optics package. The laser system is one developed for the Atomic Vapor Laser Isotope Separation (AVLIS) Program. This laser system can be configured in various ways in support of the AVLIS program objectives, and was made available to the guide star program at intermittent times on a non-interference basis. The first light transmitted into the sky was in July of 1992, at a power level of 1. 1 kW. The laser pulse width is about 32 ns, and the pulse repetition rate was 26 kHz for the 1. 1 kW configuration and 13 kHz for a 400 W configuration. The laser linewidth is tailored to match the sodium D{sub 2} absorption line, and the laser system has active control of beam pointing and wavefront quality. Because of the short pulse length the sodium transition is saturated and the laser power is not efficiently utilized. For this reason a pulse stretcher was developed, and the results of this effort will be reported. The beam is delivered via an evacuated pipe from the laser building to the guide star site, a distance of about 100 meters, and then launched vertically. A beam director provides the means to track the sky in the full AO system, but was not used in the experiments reported here. The return signal is collected by a 1/2 meter telescope with the AO package. This telescope is located 5 meters from the km launch tube. Smaller packages for photometry, wavefront measurement, and spot image and motion analysis have been used. Although the unavailability of the AVLIS laser precluded a full AO system demonstration, data supporting feasibility and providing input to the system design for a Lick Observatory AO system was obtained.

Avicola, K.; Brase, J.; Morris, J. [and others

1994-03-02

402

Star-disk interaction in Herbig Ae/Be stars  

NASA Astrophysics Data System (ADS)

The question of the mechanism of certain types of stars is important. Classical T Tauri (CTTS) stars accrete magnetospherically, and Herbig Ae/Be stars (higher-mass analogs to CTTS) are thought to also accrete magnetospherically, but the source of a kG magnetic field is unknown, since these stars have radiative interiors. For magnetospheric accretion, an equation has been derived (Hartmann, 2001) which relates the truncation radius, stellar radius, stellar mass, mass accretion rate and magnetic field strength. Currently the magnetic field of Herbig stars is known to be somewhere between 0.1 kG and 10 kG. One goal of this research is to further constrain the magnetic field. In order to do that, I use the magnetospheric accretion equation. For CTTS, all of the variables used in the equation can be measured, so I gather this data from the literature and test the equation and find that it is consistent. Then I apply the equation to Herbig Ae stars and find that the error introduced from using random inclinations is too large to lower the current upper limit of the magnetic field range. If Herbig Ae stars are higher-mass analogs to CTTS, then they should have a similar magnetic field distribution. I compare the calculated Herbig Ae magnetic field distribution to several typical magnetic field distributions using the Kolmogorov-Smirnov test, and find that the data distribution does not match any of the distributions used. This means that Herbig Ae stars do not have well ordered kG fields like CTTS.

Speights, Christa Marie

2012-09-01

403

Revised Metallicity Classes for Low-Mass Stars: Dwarfs (dM), Subdwarfs (sdM), Extreme Subdwarfs (esdM), and Ultrasubdwarfs (usdM)  

NASA Astrophysics Data System (ADS)

The current classification system of M stars on the main sequence distinguishes three metallicity classes (dwarfs: dM; subdwarfs: sdM; and extreme subdwarfs: esdM). The spectroscopic definition of these classes is based on the relative strength of prominent CaH and TiO molecular absorption bands near 7000 Å, as quantified by three spectroscopic indices (CaH2, CaH3, and TiO5). The boundaries between the metallicity classes were initially defined from a relatively small sample of only 79 metal-poor stars (subdwarfs and extreme subdwarfs). We re-examine this classification system in light of our ongoing spectroscopic survey of stars with proper motion ?>0.45'' yr-1, which has increased the census of spectroscopically identified metal-poor M stars to over 400 objects. Kinematic separation of disk dwarfs and halo subdwarfs suggest deficiencies in the current classification system. Observations of common proper motion doubles indicates that the current dM/sdM and sdM/esdM boundaries in the [TiO5, CaH2+CaH3] index plane do not follow isometallicity contours, leaving some binaries inappropriately classified as dM+sdM or sdM+esdM. We propose a revision of the classification system based on an empirical calibration of the TiO/CaH ratio for stars of near solar metallicity. We introduce the parameter ?TiO/CaH, which quantifies the weakening of the TiO band strength due to metallicity effect, with values ranging from ?TiO/CaH=1 for stars of near-solar metallicity to ?TiO/CaH~=0 for the most metal-poor (and TiO depleted) subdwarfs. We redefine the metallicity classes based on the value of the parameter ?TiO/CaH and refine the scheme by introducing an additional class of ultrasubdwarfs (usdM). We introduce sequences of sdM, esdM, and usdM stars to be used as formal classification standards. Based on observations conducted at the MDM observatory, operated jointly by the University of Michigan, Dartmouth College, Ohio State University, Columbia University, and the University of Ohio. Based on observations conducted at the Lick Observatory, operated by the University of California system.

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

2007-11-01

404

Massive Stars in Clusters and the Field  

NASA Astrophysics Data System (ADS)

What is the relation between field massive stars and clusters? Do they represent an extreme in the universal, power-law relation for stellar clustering? Or do they represent a substantially different mode of star formation? What is the origin of the clustering law itself? We examine the massive star population of the Small Magellanic Cloud and find a continuous, power-law relation between field stars and clusters. This implies that the fraction of field massive stars ranges from about 35% to 7% for most astrophysical situations, with a weak dependence on the galaxy size and/or star formation rate. We also examine the star formation history of the Galactic complex W3/W4, which is a system of three generations of hierarchical, triggered star formation. This lends some of the strongest evidence to date that superbubbles indeed trigger star formation. We speculatively link this hierarchical process to the power-law clustering of stars.

Oey, M. S.; King, N. L.; Parker, J. W.; Watson, A. M.; Kern, K. M.

2004-12-01

405

The Stars behind the Curtain  

NASA Astrophysics Data System (ADS)

ESO is releasing a magnificent VLT image of the giant stellar nursery surrounding NGC 3603, in which stars are continuously being born. Embedded in this scenic nebula is one of the most luminous and most compact clusters of young, massive stars in our Milky Way, which therefore serves as an excellent "local" analogue of very active star-forming regions in other galaxies. The cluster also hosts the most massive star to be "weighed" so far. NGC 3603 is a starburst region: a cosmic factory where stars form frantically from the nebula's extended clouds of gas and dust. Located 22 000 light-years away from the Sun, it is the closest region of this kind known in our galaxy, providing astronomers with a local test bed for studying intense star formation processes, very common in other galaxies, but hard to observe in detail because of their great distance from us. The nebula owes its shape to the intense light and winds coming from the young, massive stars which lift the curtains of gas and clouds revealing a multitude of glowing suns. The central cluster of stars inside NGC 3603 harbours thousands of stars of all sorts (eso9946): the majority have masses similar to or less than that of our Sun, but most spectacular are several of the very massive stars that are close to the end of their lives. Several blue supergiant stars crowd into a volume of less than a cubic light-year, along with three so-called Wolf-Rayet stars - extremely bright and massive stars that are ejecting vast amounts of material before finishing off in glorious explosions known as supernovae. Using another recent set of observations performed with the SINFONI instrument on ESO's Very Large Telescope (VLT), astronomers have confirmed that one of these stars is about 120 times more massive than our Sun, standing out as the most massive star known so far in the Milky Way [1]. The clouds of NGC 3603 provide us with a family picture of stars in different stages of their life, with gaseous structures that are still growing into stars, newborn stars, adult stars and stars nearing the end of their life. All these stars have roughly the same age, a million years, a blink of an eye compared to our five billion year-old Sun and Solar System. The fact that some of the stars have just started their lives while others are already dying is due to their extraordinary range of masses: high-mass stars, being very bright and hot, burn through their existence much faster than their less massive, fainter and cooler counterparts. The newly released image, obtained with the FORS instrument attached to the VLT at Cerro Paranal, Chile, portrays a wide field around the stellar cluster and reveals the rich texture of the surrounding clouds of gas and dust. Notes [1] The star, NGC 3603-A1, is an eclipsing system of two stars orbiting around each other in 3.77 days. The most massive star has an estimated mass of 116 solar masses, while its companion has a mass of 89 solar masses. More information ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and VISTA, the largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large op

2010-02-01

406

Neutron stars, strange stars, and the nuclear equation of state  

SciTech Connect

This article consists of three parts. In part one we review the present status of dense nuclear matter calculations, and introduce a representative collection of realistic nuclear equations of state which are derived for different assumptions about the physical behavior of dense matter (baryon population, pion condensation,.possible transition of baryon matter to quark matter). In part two we review recently performed non-rotating and rotating compact star calculations performed for these equations of state. The minimum stable rotational periods of compact stars, whose knowledge is of decisive importance for the interpretation of rapidly rotating pulsars, axe determined. For this purpose two different limits on stable rotation are studied: rotation at the general relativistic Kepler period (below which mass shedding at the star's equator sets in), and, secondly, rotation at the gravitational radiation-reaction instability (at which emission of gravitational waves set in which slows the star down). Part three of this article deals with the properties of hypothetical strange stars. Specifically we investigate the amount of nuclear solid crust that can be carried by a rotating strange star, and answer the question whether such objects can give rise to the observed phenomena of pulsar glitches, which is at the present time the only astrophysical test of the strange-quark-matter hypothesis.

Weber, F.; Glendenning, N.K.

1992-11-02

407

Galactic orbits of Hipparcos stars: Classification of stars  

NASA Astrophysics Data System (ADS)

The Galactic orbits of 27 440 stars of all classes with accurate coordinates and parallaxes of more than 3 mas from the Hipparcos catalogue, proper motions from the Tycho-2 catalogue, and radial velocities from the Pulkovo Compilation of Radial Velocities (PCRV) are analyzed. The sample obtained is much more representative than the Geneva-Copenhagen survey and other studies of Galactic orbits in the solar neighborhood. An estimation of the influence of systematic errors in the velocities on orbital parameters shows that the errors of the proper motions due to the duplicity of stars are tangible only in the statistics of orbital parameters for very small samples, while the errors of the radial velocities are noticeable in the statistics of orbital parameters for halo stars. Therefore, previous studies of halo orbits may be erroneous. The distribution of stars in selection-free regions of the multidimensional space of orbital parameters, dereddened colors, and absolute magnitudes is considered. Owing to the large number of stars and the high accuracy of PCRV radial velocities, nonuniformities of this distribution (apart from the well-known dynamical streams) have been found. Stars with their peri- and apogalacticons in the disk, perigalacticons in the bulge and apogalacticons in the disk, perigalacticons in the bulge and apogalacticons in the halo, and perigalacticons in the disk and apogalacticons in the halo have been identified. Thus, the bulge and the halo are inhomogeneous structures, each consisting of at least two populations. The radius of the bulge has been determined: 2 kpc.

Gontcharov, G. A.; Bajkova, A. T.

2013-10-01

408

Research and simulation of star capture based on star sensor  

NASA Astrophysics Data System (ADS)

The starlight refraction navigation is considered to be one of the most promising methods for satellite autonomous navigation. This paper mainly did research on the capture of navigation stars in starlight refraction navigation. By studying on the geometry relation between measurement star and satellite, a measurement star orientation method can be deduced which can be used to simulate the actual orbital navigation. According to this method the measurement star can be obtained at any satellite position. Then the measurement information can be modeled through which the laboratory digital simulation of starlight refraction navigation and integrated navigation can both be performed. At the mean time, confirm the navigation measurement starlight orientation combined with the star catalog. Then use starlight refraction navigation to calculate the satellite positions and velocities based on the Unscented Kalman Filter. At last, use the starlight refraction and starlight elevation integrated navigation based on the information fusion method to resolve the matter that the refraction measurement star can not be captured. Compared with merely using starlight refraction navigation, the precision of integrated navigation can be effectively improved.

Hu, Jing; Yang, Bo; Wu, Chenhao

2009-07-01

409

AGB (asymptotic giant branch): Star evolution  

SciTech Connect

Asymptotic giant branch stars are red supergiant stars of low-to-intermediate mass. This class of stars is of particular interest because many of these stars can have nuclear processed material brought up repeatedly from the deep interior to the surface where it can be observed. A review of recent theoretical and observational work on stars undergoing the asymptotic giant branch phase is presented. 41 refs.

Becker, S.A.

1987-01-01

410

Spectral atlas of helium-rich stars  

Microsoft Academic Search

An atlas of coude spectra of 33 helium-rich O- and B-stars and 11 comparison stars in the 3700-4600 A spectral range is presented. The atlas comprises stars with temperatures from 10,000 to 60,000 deg K in which He lines are visible in the spectra, and includes variable He stars; stars with spectral types O8 to B5 and magnitudes (m(v)) less

J. P. Kaufmann; U. Theil

1980-01-01

411

Molecular cloud evolution and star formation  

Microsoft Academic Search

The origin and growth of molecular clouds is described and mechanisms for molecular cloud support are reviewed. Cloud disruption\\u000a is discussed with emphasis on star formation efficiency. Issues pertaining to massive star enhanced star formation are summarized,\\u000a and a mechanism for bimodal star formation is presented. Applications are made to the global star formation rate and to starburst\\u000a galaxies.

Joseph Silk

1985-01-01

412

U Antliae --- A Dying Carbon Star  

NASA Astrophysics Data System (ADS)

U Antliae is one of the brightest carbon stars in the southern sky. It is classified as an N0 carbon star and an Lb irregular variable. This star has a very unique spectrum and is thought to be in a transition stage from an asymptotic giant branch star to a planetary nebula. This paper discusses possible atomic and molecular line identifications for features seen in high-dispersion spectra of this star at wavelengths from 4975 Å through 8780 Å.

Bidelman, W. P.; Cowley, C. R.; Luttermoser, D. G.

2009-09-01

413

Supernovae in the Lives of Stars  

NSDL National Science Digital Library

Many people think the different stages in the life of a star are actually different types of stars, rather than just stages in the life of a single star. In this fun activity learners discover the lifecycle of stars and learn when supernovae happen. This activity can be used indoors or outdoors, before a star party, in a classroom, or at a club meeting. The pdf contains step-by-step instructions, photos, presentation tips, background information, and ready-to-print handouts.

Pacific, Astronomical S.

2008-01-01

414

Integrated Focal Plane Star Sensor.  

National Technical Information Service (NTIS)

A theoretical analysis on the detectors suitable for the Infrared Space Observer (ISO) Integrated Focal Plane Star Sensor (IFPSS) design are presented, together with system configuration concepts. A simplified configuration with respect to the electronic ...

G. Borghi M. Carboncini M. Stagi

1987-01-01

415

Kepler Mission Star Field Lithograph  

NSDL National Science Digital Library

This two-sided 8in. X 10in. print document depicts the Kepler Mission Field of View imposed upon a star field that includes the constellations Cygnus and Delphinus on the front. A description of the mission, the star selection constraints, the location of the field in the night sky, distances to the stars, and the CCD layout is included on the back. An image on the back also illustrates the distance the field is from the galactic center and the size of the field of view. NASA's Kepler mission is a spaceborne telescope specifically designed to survey our region of the Milky Way galaxy to detect and characterize hundreds of Earth-size and smaller planets in or near the habitable zone. The habitable zone encompasses the distances from a star where liquid water can exist on a planet's surface.

2007-04-01

416

Spots on T Tauri stars  

NASA Astrophysics Data System (ADS)

Periodic light curves were recorded for the following 15 T Tauri stars (for nine of which this was the first detection of periodic variability): V 410 Tau, DF Tau, UX Tau A, FK 1, FK 2, WK 2, DN Tau, GW Ori, SY Cha, LH(alpha) 332-20, LH(alpha) 332-21, CoD-33-deg 10685, RY Lup, SR 12, and SR 9. The previously reported periodic variability of the SY Cha and RY Lup stars was confirmed. These periodic variations are thought to result from rotational modulation by a group of spots at the stellar surface. The properties of spots on 11 stars were deduced from extensive light-curve synthesis. In most cases, they were found to be comparable to the properties of spots found on RS CVn stars.

Bouvier, J.; Bertout, C.

1989-02-01

417

Effective temperatures of AP stars  

Microsoft Academic Search

A new method of determination of the effective temperatures of Ap stars is proposed. The method is based on the fact that the slopes of the energy distribution in the Balmer continuum near the Balmer jump for ``normal\\

N. A. Sokolov

1998-01-01

418

Star Formation a Literature Survey.  

National Technical Information Service (NTIS)

The formation of stars from galactic clouds is considered. Dynamic collapse, fragmentation, and the Helmholtz-Kelvin contraction are discussed. Galactic cloud rotation and the influence of a magnetic field on stellar evolution are reviewed. The formation ...

P. Ingvarson

1970-01-01

419

A young star's hectic months  

NASA Astrophysics Data System (ADS)

We present preliminary results ol the optical photometric and spectroscopic monitoring ol the young eruptive variable star PV Cephei, performed during its recent conspicuous lading in 2008-2009, and try to find the reasons of the observed variations.

Elek, Elza; Kun, Mária

2010-03-01

420

Star Formation in Molecular Clouds  

NASA Astrophysics Data System (ADS)

Stars and star clusters form by gravoturbulent fragmentation of interstellar gas clouds. The supersonic turbulence ubiquitously observed in Galactic molecular gas generates strong density fluctuations with gravity taking over in the densest and most massive regions. Collapse sets in to build up stars. Turbulence plays a dual role. On global scales it provides support, while at the same time it can promote local collapse. Stellar birth is thus intimately linked to the dynamical behavior of parental gas cloud, which governs when and where protostars form, and how they contract and grow in mass via accretion from the surrounding cloud material. The thermodynamic behavior of the star forming gas plays a crucial part in this process and influences the stellar mass function as well as the dynamic properties of the nascent stellar cluster. This lecture provides a critical review of our current understanding of stellar birth and compares observational data with competing theoretical models.

Klessen, R. S.

2011-11-01

421

Sleuthing the Isolated Compact Stars  

NASA Astrophysics Data System (ADS)

In the early 1990's, isolated thermally-emitting neutron stars accreting from the interstellar medium were predicted to show up in their thousands in the ROSAT soft X-ray all-sky survey. The glut of sources would provide unprecedented opportunities for probing the equation of state of ultra-dense matter. Only seven objects have been firmly identified to date. The reasons for this discrepency are discussed and recent high resolution X-ray spectroscopic observations of these objects are described. Spectra of the brightest of the isolated neutron star candidates, RX J1856.5-3754, continue to present interpretational difficulties for current neutron star model atmospheres and alternative models are briefly discussed. RX J1856.5-3754 remains a valid quark star candidate.

Drake, J. J.

2004-08-01

422

Neutron skins and neutron stars  

NASA Astrophysics Data System (ADS)

Background: The neutron skin of a heavy nucleus as well as many neutron-star properties are highly sensitive to the poorly constrained density dependence of the symmetry energy.Purpose: To provide for the first time meaningful theoretical errors and to assess the degree of correlation between the neutron-skin thickness of 208Pb and several neutron-star properties.Methods: A proper covariance analysis based on the predictions of an accurately calibrated relativistic functional “FSUGold” is used to quantify theoretical errors and correlation coefficients.Results: We find correlation coefficients of nearly 1 (or -1) between the neutron-skin thickness of 208Pb and a host of observables of relevance to the structure, dynamics, and composition of neutron stars.Conclusions: We suggest that a follow-up Lead Radius Experiment (PREX) measurement, ideally with a 0.5% accuracy, could significantly constrain the equation of state of neutron-star matter.

Fattoyev, F. J.; Piekarewicz, J.

2012-07-01

423

Zenith Star Support Experiment Design.  

National Technical Information Service (NTIS)

Experiments are proposed that can be performed on the SPICE structure in support of the Zenith Star Experiments. The fourteen experimental proposals fall into four categories: isolation of a space beam expander from on-board disturbances, evaluation of po...

J. W. Dettmer

1995-01-01

424

The Star Guide: Learn How To Read the Night Sky Star by Star, 2nd Edition  

NASA Astrophysics Data System (ADS)

A thorough revision of the bestselling guide to the night sky - over 100,000 copies sold! The first edition of The Star Guide introduced readers of all ages to the wonders of the night sky. Now comes the highly anticipated revised edition, expertly updated by one of the world's leading writers on astronomy and space. Illustrated throughout in full color, the guide features spectacular new photographs from the Hubble Space Telescope, more than 60 easy-to-use star charts, and an invaluable detachable planisphere. Special sections explain the nature of stars and galaxies and what makes the universe tick.

Kerrod, Robin

2005-02-01

425

Pulsars and Isolated Neutron Stars  

Microsoft Academic Search

The idea of neutron stars can be traced back to the early 1930s, when Subrahmanyan Chandrasekhar discovered that there is no way for a collapsed stellar\\u000a core with a mass more than 1.4 times the solar mass, M{in?}, to hold itself up against gravity once its nuclear fuel is exhausted.\\u000a This implies that a star left with M > 1.4

W. Becker; F. Haberl; J. Trümper

2002-01-01

426

Maximum mass of neutron stars  

NASA Astrophysics Data System (ADS)

We determine the structure of neutron stars within a Brueckner-Hartree-Fock approach based on realistic nucleon-nucleon, nucleon-hyperon, and hyperon-hyperon interactions. Our results indicate rather low maximum masses below 1.4 solar masses. This feature is insensitive to the nucleonic part of the EOS due to a strong compensation mechanism caused by the appearance of hyperons and represents thus strong evidence for the presence of nonbaryonic “quark” matter in the interior of heavy stars.

Schulze, H.-J.; Polls, A.; Ramos, A.; Vidaña, I.

2006-05-01

427

?-condensation and neutron star cooling  

NASA Astrophysics Data System (ADS)

We show, within the context of an independent particle model, that ?- condensation should occur in neutron stars having baryon densities exceeding~0.4 - 0.5 fm-3. This high concentration of ?- implies a very fast cooling rate for `hot' neutron stars. Work supported by the Air Force Office of Scientific Research, Office of Aerospace Research, United States Air Force, under AFOSR Grant 70-1866A.

Kogut, J.; Manassah, J. T.

1972-09-01

428

Neutron Star in Cassiopeia A  

NASA Video Gallery

This brief animation shows Cassiopeia A, the remains of a massive star 11,000 light years away from Earth, along with an illustrated inset of a neutron star within the supernova. X-rays from NASA's Chandra X-ray Observatory are shown in red, green and blue along with optical data from the Hubble Space Telescope in gold. Credit: X-ray: NASA/CXC/xx; Optical: NASA/STScI; Illustration: NASA/CXC/ M.Weiss

Sydney B

2011-02-23

429

Complexity and neutron star structure  

NASA Astrophysics Data System (ADS)

We apply the statistical measure of complexity introduced by López-Ruiz, Mancini and Calbet (1995) [1] to neutron star structure. We continue the recent application of Sañudo and Pacheco (2009) [2] to white dwarfs. The interplay of gravity, the short-range nuclear force and the very short-range weak interaction shows that neutron stars, under the current theoretical framework, are ordered (low complexity) systems.

Chatzisavvas, K. Ch.; Psonis, V. P.; Panos, C. P.; Moustakidis, Ch. C.

2009-10-01

430

Northern Astrographic Catalog reference stars  

Microsoft Academic Search

A high density reference star catalog is being compiled at the U.S. Naval Observatory for the purpose of making new reductions of the Astrographic Catalog. The first version of this catalog will contain 215,000 stars on the system of FK4. The northern half is completed and contains 130,000 positions and proper motions with mean errors less than 0\\

T. E. Corbin; S. E. Urban

1989-01-01

431

How Far Are the Stars?  

ERIC Educational Resources Information Center

|On any night, the stars seen in the sky can be as close to Earth as a few light-years or as distant as a few thousand light-years. Distances this large are hard to comprehend. The stars are so far away that the fastest spacecraft would take tens of thousands of years to reach even the nearest one. Yet, astronomers have been able to accurately…

Murphy, Edward; Bell, Randy L.

2005-01-01

432

STAR Vertex Detector Upgrade Development  

SciTech Connect

We report on the development and prototyping efforts undertaken with the goal of producing a micro-vertex detector for the STAR experiment at the RHIC accelerator at BNL. We present the basic detector requirements and show a sensor development path, conceptual mechanical design candidates and readout architecture. Prototyping and beam test results with current generation MimoSTAR-2 sensors and a readout system featuring FPGA based on-the-fly hit finding and data sparsification are also presented.

Greiner, Leo C.; Matis, Howard S.; Stezelberger, Thorsten; Vu,Chinh Q.; Wieman, Howard; Szelezniak, Michal; Sun, Xiangming

2008-01-28

433

GRBs from the First Stars  

SciTech Connect

We present an estimate of the Gamma Ray Bursts which should be expected from metal-free, elusive first generation of stars known as PopulationIII (PopIII). We derive the GRB rate from these stars from the Stellar Formation Rate obtained in several Reionization scenarios available in the literature. In all of the analyzed models we find that GRBs from PopIII are subdominant with respect to the ''standard'' (PopII) ones up to z {approx} 10.

Iocco, Fabio; /Naples U. /KIPAC, Menlo Park

2007-04-16

434

Star Formation in Dense Clusters  

NASA Astrophysics Data System (ADS)

A model of core-clump accretion with equally likely stopping describes star formation in the dense parts of clusters, where models of isolated collapsing cores may not apply. Each core accretes at a constant rate onto its protostar, while the surrounding clump gas accretes as a power of protostar mass. Short accretion flows resemble Shu accretion and make low-mass stars. Long flows resemble reduced Bondi accretion and make massive stars. Accretion stops due to environmental processes of dynamical ejection, gravitational competition, and gas dispersal by stellar feedback, independent of initial core structure. The model matches the field star initial mass function (IMF) from 0.01 to more than 10 solar masses. The core accretion rate and the mean accretion duration set the peak of the IMF, independent of the local Jeans mass. Massive protostars require the longest accretion durations, up to 0.5 Myr. The maximum protostar luminosity in a cluster indicates the mass and age of its oldest protostar. The distribution of protostar luminosities matches those in active star-forming regions if protostars have a constant birthrate but not if their births are coeval. For constant birthrate, the ratio of young stellar objects to protostars indicates the star-forming age of a cluster, typically ~1 Myr. The protostar accretion luminosity is typically less than its steady spherical value by a factor of ~2, consistent with