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471. Radial velocities of 47 Oph
ID:
ivo://CDS.VizieR/J/AJ/149/110
Title:
Radial velocities of 47 Oph
Short Name:
J/AJ/149/110
Date:
21 Oct 2021
Publisher:
CDS
Description:
Although 47 Oph has been shown to be a binary with a period of ~27days using both spectroscopic and interferometric techniques, only a preliminary orbit has been obtained in the previous work due to the shortage of high precision measurements. Since 1997, new spectroscopic and interferometric measurements have been obtained with much higher precision by the spectrograph of the 2.16m telescope at Xinglong station and the Navy Precision Optical Interferometer, respectively. Combining all of the measurements, a three-dimensional orbit is obtained with high precision in this work. Thus, the component masses are calculated to be 1.50+/-0.06 and 1.34+/-0.06M_{sun}_, respectively. The orbital parallax is 32.6+/-0.6mas, which is consistent with the Hipparcos parallax. With the known apparent magnitudes and color indices of the components, the derived luminosities are 7.80+/-0.36 and 3.41+/-0.25L_{sun}_. The estimated radii of the components are 2.06+/-0.07 and 1.36+/-0.06R_{sun}_. Finally, the evolutionary status of the components are investigated with the help of a stellar evolution model.
472. Radial Velocities of Stars in M4
ID:
ivo://CDS.VizieR/J/ApJ/443/124
Title:
Radial Velocities of Stars in M4
Short Name:
J/ApJ/443/124
Date:
21 Oct 2021
Publisher:
CDS
Description:
The internal stellar velocity distribution of the globular cluster M4 is evaluated from nearly 200 new radial velocity measurements good to 1 km/s and a rederivation of existing proper motions. The mean radial velocity of the cluster is 70.9 +/- 0.6 km/s. The velocity dispersion is 3.5 +/- 0.3 km/s at the core, dropping marginally towards the outskirts. Such a low internal dispersion is somewhat at odds with the cluster's orbit, for which the perigalacticon is sufficiently close to the galactic center that the probability of cluster disruption is high; a tidal radius two-thirds the currently accepted value would eliminate the discrepancy. The cluster mass-to-light ratio is also small, M/L_V = 1.0 +/- 0.4 in solar units. M4 thus joins M22 as a cluster of moderate mass and concentration with a mass-to-light ratio among the lowest known. The astrometric distance to the cluster is also smaller than expected, 1.72 +/- 0.14 kpc. This is only consistent with conventional estimates of the luminosity of horizontal branch stars provided an extinction law R = A_V/E(B-V) ~ 4 is adopted, as has been suggested recently by several authors.
473. Radial velocities & orbital data, 5 triple stars
ID:
ivo://CDS.VizieR/J/AJ/160/251
Title:
Radial velocities & orbital data, 5 triple stars
Short Name:
J/AJ/160/251
Date:
21 Oct 2021
Publisher:
CDS
Description:
Joint analysis of radial velocities and position measurements of five hierarchical stellar systems is undertaken to determine elements of their inner and outer orbits and, whenever possible, their mutual inclinations. The inner and outer periods are 12.9 and 345yr for HD12376 (ADS1613), 1.14 and ~1500yr for HD19971 (ADS2390), 8.3 and 475yr for HD89795 (ADS7338), 1.11 and 40yr for HD152027, 0.69 and 7.4yr for HD190412. The latter system with its coplanar and quasi-circular orbits belongs to the family of compact planetary-like hierarchies, while the orbits in HD12376 have a mutual inclination of 131{deg}.
474. Radial Velocities with Astrometric Data
ID:
ivo://CDS.VizieR/III/239
Title:
Radial Velocities with Astrometric Data
Short Name:
III/239
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalogue of radial velocities of Galactic stars with high precision astrometric data (CRVAD) is the result of a merging of star lists from the General Catalog of Mean Radial Velocities (GCRV, Cat. III/213) and from the All-sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5, Cat. I/280). The cross identification of GCRV and ASCC-2.5 objects was carried out with help of coordinate, magnitude, colour and/or spectral type criteria. Data from the Catalogue of Components of Double and Multiple Stars (CCDM, Cat. I/274) were taken into account for the identification of multiple system components. 34553 stars of the ASCC-2.5 were identified with 33509 stars of the GCRV, i.e. 33509 stars of the GCRV have one entry in the ASCC-2.5, and 1044 objects have two entries. The catalogue includes accurate equatorial coordinates J2000, proper motions and trigonometric parallaxes in the Hipparcos system, B and V magnitudes in Johnson system, spectral classes, multiplicity and variability flags from the ASCC-2.5, and radial velocities, stellar magnitudes and spectra from the GCRV. Stars are sorted in right ascension J2000 order. 3967 stars were selected as radial velocity standard candidates (file rv_std.dat). These stars: - do not have any multiplicity and/or variability flags both in the GCRV and ASCC-2.5; - have standard errors of equatorial coordinates e <= 40 mas; - have standard errors of proper motions e_pm <= 4 mas/yr; - have standard errors of V magnitude e_V <= 0.05 mag and (B-V) colour e_(B-V) <= 0.07 mag; - have standard errors of radial velocity e_RV <= 2 km/s or quality index A or B, which corresponds to e_RV 0.74 and 1.78 km/s; - have at least four RV observations N_RV.
475. Radio-optical reference frame link
ID:
ivo://CDS.VizieR/I/325
Title:
Radio-optical reference frame link
Short Name:
I/325
Date:
21 Oct 2021
Publisher:
CDS
Description:
Between 1997 and 2004 several observing runs were conducted mainly with the CTIO 0.9m to image ICRF counterparts (mostly QSOs) in order to determine accurate optical positions. Contemporary to these deep CCD images the same fields were observed with the USNO astrograph in the same bandpass. These provide accurate positions on the Hipparcos/Tycho-2 system for stars in the 10 to 16 magnitude range used as reference stars for the deep CCD imaging data. Here we present final optical position results of 413 sources based on astrograph data reductions using UCAC2 and UCAC4 type reference stars. These optical positions are compared to radio VLBI positions. The current optical system is not perfectly aligned to the ICRF radio system with rigid body rotation angles of 3 to 5 mas (3{sigma}) found between them for all 3 axes. Furthermore, statistically, the optical-radio position differences are found to exceed the total, combined, known errors in the observations. Systematic errors in the optical reference stars as well as physical offsets between the centers of optical and radio emissions are both identified as likely causes. A detrimental, astrophysical, random noise (DARN) component is postulated to be on about the 10mas level. If confirmed by future observations, this could severely limit the Gaia to ICRF reference frame alignment accuracy to an error of about 0.5mas per coordinate axis with the current number of sources envisioned to provide the link. A list of 36 ICRF sources without the detection of an optical counterpart to a limiting magnitude of about R=22 is provided as well.
476. Radio reference frame
ID:
ivo://CDS.VizieR/J/AJ/110/880
Title:
Radio reference frame
Short Name:
J/AJ/110/880
Date:
21 Oct 2021
Publisher:
CDS
Description:
A catalogue is presented based on the radio positions of 436 extragalactic sources distributed over the entire sky. The positional accuracy of the sources is better than 3 milliarcsec (mas) in both coordinates, with the majority of the sources having errors better than 1mas. This catalogue is based upon a general solution of all applicable dual frequency 2.3 and 8.4GHz Mark-III VLBI data available through the end of 1993 consisting of 1,015,292 pairs of group delay and phase delay rate observations. Details and positions are also given for an additional 124 objects that either need further observation or are currently unsuitable for the definition of a reference frame. The final orientation of the catalogue has been obtained by a rotation of the positions into the system of the International Earth Rotation Service and is consistent with the FK5 J2000.0 optical system, within the limits of the link accuracy.
477. Radio source distribution
ID:
ivo://CDS.VizieR/J/A+A/506/1477
Title:
Radio source distribution
Short Name:
J/A+A/506/1477
Date:
21 Oct 2021
Publisher:
CDS
Description:
Information on physical characteristics of astrometric radio sources, such as magnitude and redshift, is of great importance for many astronomical studies. However, data usually used in radio astrometry is often incomplete and outdated. Our purpose is to study the optical characteristics of more than 4000 radio sources observed by the astrometric VLBI technique since 1979. We also studied the effect of the asymmetry in the distribution of the reference radio sources on the correlation matrices between vector spherical harmonics of the first and second degrees. The radio source characteristics were mainly taken from the NASA/IPAC Extragalactic Database (NED). Characteristics of the gravitational lenses were checked with the CfA-Arizona Space Telescope LEns Survey. SIMBAD and HyperLeda databases were also used to clarify the characteristics of some objects. Also we simulated and investigated a list of 4000 radio sources evenly distributed around the celestial sphere. We estimated the correlation matrices between the vector spherical harmonics using the real as well as modelled distribution of the radio sources.
478. Radio source selection for the ICRF
ID:
ivo://CDS.VizieR/J/A+A/493/317
Title:
Radio source selection for the ICRF
Short Name:
J/A+A/493/317
Date:
21 Oct 2021
Publisher:
CDS
Description:
The most accurate realization of a quasi inertial reference frame, the International Celestial Reference Frame (ICRF), is made of 212 defining extragalactic radio sources whose coordinates are determined using VLBI observations. Recent studies demonstrated however that using other sets of sources could improve the frame stability. This study examines a simple radio source selection scheme to define celestial reference frame axes more stable than the ones as currently defined by the ICRF. After having derived source coordinate time series from 26 years of VLBI observations, we select the most suitable sources on the basis of their positional variability (rms and slope), and observational history. We determine the axis stability of the frame defined by the selection, as well as its suitability for global geodetic VLBI analyses, i.e., determination of Earth orientation parameters and source and station coordinates.
479. Radio star proper motions
ID:
ivo://CDS.VizieR/J/AJ/133/906
Title:
Radio star proper motions
Short Name:
J/AJ/133/906
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the Very Large Array, linked with the Pie Town Very Long Baseline Array antenna, to determine astrometric positions of 46 radio stars in the International Celestial Reference Frame (ICRF). Positions were obtained in the ICRF directly through phase referencing of the stars to nearby ICRF quasars whose positions are accurate at the 0.25mas level. Radio star positions are estimated to be accurate at the 10mas level, with position errors approaching a few milliarcseconds for some of the stars observed. Our measured positions were combined with previous measurements taken from as early as 1978 to obtain proper-motion estimates for all 46 stars with average uncertainties of ~1.7mas/yr.
480. Redshift of 97 spirals
ID:
ivo://CDS.VizieR/J/A+A/310/353
Title:
Redshift of 97 spirals
Short Name:
J/A+A/310/353
Date:
21 Oct 2021
Publisher:
CDS
Description:
Persistent claims have been made over the last ~15yr that extragalactic redshifts, when corrected for the Sun's motion around the Galactic centre, occur in multiples of ~24 or ~36km/s. A recent investigation by us of 40 spiral galaxies out to 1000km/s, with accurately measured redshifts, gave evidence of a periodicity ~37.2-37.7km/s. Here we extend our enquiry out to the edge of the Local Super cluster (~2600km/s), applying a simple and robust procedure to a total of 97 accurately determined redshifts. We find that, when corrected for related vectors close to recent estimates of the Sun's galactocentric motion, the redshifts of spirals are strongly periodic (P~37.6km/s). The formal confidence level of the result is extremely high, and the signal is seen independently with different radio telescopes. We also examine a further sample of 117 spirals observed with the 300-foot Green Bank telescope alone. The periodicity phenomenon appears strongest for the galaxies linked by group membership, but phase coherence probably holds over large regions of the Local Supercluster.

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