scholarly journals A redshift database towards the Shapley supercluster region

2020 ◽  
Vol 638 ◽  
pp. A27
Author(s):  
Hernán Quintana ◽  
Dominique Proust ◽  
Rolando Dünner ◽  
Eleazar R. Carrasco ◽  
Andreas Reisenegger
Keyword(s):  
Velocity Measurement ◽  
Average Velocity ◽  
Radial Velocities ◽  
Velocity Data ◽  
Velocity Measurements ◽  
General Terms ◽  
Future Publication

We present a database and catalogue of radial velocities of galaxies towards the region of the Shapley Supercluster (SSC) based on 18 129 measured velocities for 10 702 galaxies in the approximately 300 square degree area between 12h43m00s < RA < 14h17m00s and −23° 30′00″ > Dec >   − 38° 30′00″. The database contains velocity measurements that have been reported in the literature up until 2015. It also includes 5084 velocities, corresponding to 4617 galaxies, observed by us at Las Campanas Observatory and Cerro Tololo Inter-American Observatory, which had not been reported individually until now. Of the latter, 2585 correspond to galaxies with no other previously published velocity measurement before 2015. Every galaxy in the velocity database has been identified with a galaxy extracted from the SuperCOSMOS photometric catalogues. We also provide a combined average velocity catalogue for all 10 702 galaxies with measured velocities, adopting the SuperCOSMOS positions as a homogeneous base. A general magnitude cut-off at R2 = 18.0 mag was adopted (with exceptions only for some of the new reported velocities). In general terms, we confirm the overall structure of the SSC as reported in earlier papers. However, the more extensive velocity data show finer structures, which is to be discussed in a future publication.

scholarly journals Precise radial velocities of giant stars

2019 ◽  
Vol 625 ◽  
pp. A22 ◽  
Author(s):  
Katja Reichert ◽  
Sabine Reffert ◽  
Stephan Stock ◽  
Trifon Trifonov ◽  
Andreas Quirrenbach
Keyword(s):  
Radial Velocity ◽  
Statistical Power ◽  
Radial Velocities ◽  
Dynamical Stability ◽  
Published Data ◽  
Data Sets ◽  
Velocity Data ◽  
Velocity Measurements ◽  
Velocity Variations ◽  
Radial Velocity Data

Context. Radial-velocity variations of the K giant star Aldebaran (α Tau) were first reported in the early 1990s. After subsequent analyses, the radial-velocity variability with a period of ∼629 d has recently been interpreted as caused by a planet of several Jovian masses. Aims. We want to further investigate the hypothesis of an extrasolar planet around Aldebaran. Methods. We combine 165 new radial-velocity measurements from Lick Observatory with seven already published data sets comprising 373 radial-velocity measurements. We perform statistical analyses and investigate whether a Keplerian model properly fits the radial velocities. We also perform a dynamical stability analysis for a possible two-planet solution. Furthermore, the possibility of oscillatory convective modes as cause for the observed radial-velocity variability is discussed. Results. As best Keplerian fit to the combined radial-velocity data we obtain an orbit for the hypothetical planet with a smaller period (P = 607 d) and a larger eccentricity (e = 0.33 ± 0.04) than the previously proposed one. However, the residual scatter around that fit is still large, with a standard deviation of 117 ms−1. In 2006/2007, the statistical power of the ∼620 d period showed a temporary but significant decrease. Plotting the growth of power in reverse chronological order reveals that a period around 620 d is clearly present in the newest data but not in the data taken before ∼2006. Furthermore, an apparent phase shift between radial-velocity data and orbital solution is observable at certain times. A two-planet Keplerian fit matches the data considerably better than a single-planet solution, but poses severe dynamical stability issues. Conclusions. The radial-velocity data from Lick Observatory do not further support but in fact weaken the hypothesis of a substellar companion around Aldebaran. Oscillatory convective modes might be a plausible alternative explanation of the observed radial-velocity variations.

The CORAVEL Radial Velocity Data Base

2017 ◽  
Vol 13 (S334) ◽  
pp. 271-272
Author(s):  
Stéphane Udry ◽  
Maxime Marmier ◽  
Michel Mayor ◽  
Johannes Andersen ◽  
Birgitta Nordström
Keyword(s):  
Radial Velocity ◽  
Data Base ◽  
Radial Velocities ◽  
Velocity Data ◽  
Radial Velocity Data

AbstractFrom 1977 to 1999, thousands of accurate radial velocities in both hemispheres were made on a large variety of programmes with the two CORAVEL scanners. The data base of ~350000 individual observations will now be made available to complement the Gaia data.

Using Drifter Velocity Measurements to Assess and Constrain Coarse-Resolution Ocean Models

2021 ◽  
Author(s):  
Mengnan Zhao ◽  
Rui M. Ponte ◽  
Ou Wang ◽  
Rick Lumpkin
Keyword(s):  
Time Variable ◽  
Ocean Dynamics ◽  
Careful Examination ◽  
Velocity Data ◽  
Velocity Measurements ◽  
Data Errors ◽  
Coarse Resolution ◽  
Surface Circulation ◽  
Ocean Models ◽  
Data Constraints

AbstractProperly fitting ocean models to observations is crucial for improving model performance and understanding ocean dynamics. Near-surface velocity measurements from the Global Drifter Program (GDP) contain valuable information about upper ocean circulation and air-sea fluxes on various space and time scales. This study explores whether GDP measurements can be used for usefully constraining the surface circulation from coarse-resolution ocean models, using global solutions produced by the consortium for Estimating the Circulation and Climate of the Ocean (ECCO) as an example. To address this problem, a careful examination of velocity data errors is required. Comparisons between an ECCO model simulation, performed without any data constraints, and GDP and Ocean Surface Current Analyses Real-time (OSCAR) velocity data, over the period 1992–2017, reveal considerable differences in magnitude and pattern. These comparisons are used to estimate GDP data errors in the context of the time-mean and time-variable surface circulations. Both instrumental errors and errors associated with limitations in model physics and resolution (representation errors) are considered. Given the estimated model-data differences, errors and signal-to-noise ratios, our results indicate that constraining ocean state estimates to GDP can have a substantial impact on the ECCO large-scale time-mean surface circulation over extensive areas. Impact of GDP data constraints on the ECCO time-variable circulation would be weaker and mainly limited to low latitudes. Representation errors contribute substantially to degrading the data impacts.

scholarly journals The empirical period-radius relation for pulsating stars: a synthesis based on photometric and radial velocity measurements

1986 ◽  
Vol 118 ◽  
pp. 273-274
Author(s):  
G. Burki
Keyword(s):  
Radial Velocity ◽  
Stellar Evolution ◽  
Variable Stars ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
Pulsating Stars ◽  
Powerful Test ◽  
The Mean

The relation existing between the radius and the period for the pulsating stars of a given class constitutes a powerful test for the theory of stellar evolution and for the identification of the pulsation modes. In recent years, several authors have determined the mean radius of a lot of pulsating stars of various classes by applying the Baade-Wesselink method. Fig. 1 presents the resulting general logP - logR diagram grouping these determinations. The sources for the radii are given by Burki and Meylan (1986). The variable stars in known binaries have been excluded since the presence of a companion biases the radius calculation (Burki, 1984). The determinations marked by arrows are based on the radial velocities by CORAVEL (1m telescope at the Haute-Provence Observatory, France) or/and on the photometry in the Geneva system (40cm and 70cm telescopes at La Silla Observatory, Chile).

Average Velocity Measurements in Six Automotive Torque Converters: Part I — Pump Measurements

2001 ◽  
Vol 44 (4) ◽  
pp. 511-522 ◽  
Author(s):  
Warren D. Claudel ◽  
Ronald D. Flack ◽  
Alexander Yermakov
Keyword(s):  
Average Velocity ◽  
Velocity Measurements ◽  
Torque Converters

scholarly journals Dealing with activity in RV planet searches

2015 ◽  
Vol 11 (A29A) ◽  
pp. 193-195
Author(s):  
Isabelle Boisse
Keyword(s):  
Time Series ◽  
Radial Velocity ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
Stellar Activity ◽  
The Future

AbstractPrecise radial velocity measurements of a star allow to search for planets. But this method has to face with irregularly time series. Stellar variabilities: pulsation, granulation, stellar activity on a short and long timescale, also modify the measure of the radial velocities. There is indeed a growing literature of controversies on how a signal is interpreted as a planet or due to stellar activity. I present how the star variations change the measured RVs, which techniques and indices are used by several teams to disentangle activity and planets, and the future options that are being studied.

scholarly journals The LAMOST spectroscopic survey of planetary nebulae in M31 and M33

2016 ◽  
Vol 12 (S323) ◽  
pp. 388-389
Author(s):  
Maosheng Xiang ◽  
Xiaowei Liu ◽  
Meng Zhang ◽  
Haibo Yuan ◽  
Zhiying Huo
Keyword(s):  
Radial Velocity ◽  
Planetary Nebulae ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
The Galaxy ◽  
Galaxy Center ◽  
Projected Distance

AbstractWe present LAMOST observations and radial velocity measurements of about 1500 planetary nebulae (PNe) in M31 and M33. Most of the PNe are previously known, but 36 of them are newly discovered in the outskirts of M31, and the furthest one has a projected distance larger than 50 kpc away from the galaxy center. Eighteen objects in the area of M33 are probably newly discovered PNe, and quite a few of them are associated with previously known clusters. For all the 1500 PNe, homogeneous radial velocities are measured from the LAMOST spectra, with a typical uncertainty of a few km s−1.

Reliability Of Peak And Average Velocity Measurements During Sit-to-stand Assessments Using A Portable Linear Transducer

2016 ◽  
Vol 48 ◽  
pp. 796
Author(s):  
Jamie C. Clark ◽  
Cameron S. Mackey ◽  
Ryan M. Thiele ◽  
Ty B. Palmer ◽  
Doug B. Smith
Keyword(s):  
Average Velocity ◽  
Velocity Measurements ◽  
Sit To Stand ◽  
Linear Transducer

AN EXPERIMENTAL INVESTIGATION OF FACTORS AFFECTING ELASTIC WAVE VELOCITIES IN POROUS MEDIA

Geophysics ◽  
1958 ◽  
Vol 23 (3) ◽  
pp. 459-493 ◽  
Author(s):  
M. R. J. Wyllie ◽  
A. R. Gregory ◽  
G. H. F. Gardner
Keyword(s):  
Experimental Investigation ◽  
Porous Media ◽  
Oil And Gas ◽  
Velocity Data ◽  
Velocity Measurements ◽  
Factors Affecting ◽  
Gas Saturation ◽  
Wave Velocities ◽  
Time Average ◽  
Made In

An experimental investigation has been made of the factors which affect the velocity of vibratory signals in porous media. It is shown from the results of experiments carried out on appropriate natural and synthetic porous systems that the time‐average formula previously suggested by Wyllie, Gregory, and L. W. Gardner is of considerable utility. This formula states that [Formula: see text] where [Formula: see text] measured, [Formula: see text] in saturating liquid, [Formula: see text] in rock solid, and ϕ=volumetric porosity fraction. The effects are examined of differential compacting pressures on the applicability of this formula to consolidated and unconsolidated rocks. It is shown that the time‐average relationship cannot be applied to determine the total volumetric porosity of carbonate rocks which are vugular and fractured. In such rocks, paradoxically, this circumstance may be advantageous because of the lithological information that may be obtained from an appropriate combination of velocity and nuclear log data. The effects of oil and gas saturation on velocity have been examined experimentally and are found to be comparatively minor. The combination of velocity data with information from electric logs in order to locate zones of oil and gas saturation is shown to be generally valuable; this is particularly so when holes are drilled with oil‐base mud. Some discussion is given of the possible effects on velocity measurements of the relative wettability of rock surfaces by various liquids. Owing to instrumental limitations, it cannot necessarily be assumed that measurements made in the laboratory are directly applicable to the interpretation of velocity data obtained under field conditions.

Velocity Measurement using the Fdoa Method in Ground-Based Radio Navigation System

2014 ◽  
Vol 21 (2) ◽  
pp. 363-376 ◽  
Author(s):  
Jarosław Sadowski
Keyword(s):  
Navigation System ◽  
Velocity Measurement ◽  
Moving Objects ◽  
Radio Networks ◽  
Position Estimation ◽  
Velocity Measurements ◽  
Radio Navigation ◽  
Wave Measurements ◽  
Radio Navigation System ◽  
Full Synchronization

Abstract Velocity is one of the main navigation parameters of moving objects. However some systems of position estimation using radio wave measurements cannot provide velocity data due to limitation of their performance. In this paper a velocity measurement method for the DS-CDMA radio navigation system is proposed, which does not require full synchronization of reference stations carrier frequencies. The article presents basics of FDOA (frequency difference of arrival) velocity measurements together with application of this method to an experimental radio navigation system called AEGIR and with some suggestions about the possibility to implement such FDOA measurements in other kinds of asynchronous DS-CDMA radio networks. The main part of this paper present results of performance evaluation of the proposed method, based on laboratory measurements

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