Dependence of the Solar Apex upon Proper Motion and Cause of the Different Positions of the Apex Yielded by Radial Velocities and Proper Motions

1917 ◽  
Vol 45 ◽  
pp. 103
Author(s):  
C. D. Perrine
Keyword(s):  
Proper Motion ◽  
Radial Velocities ◽  
Proper Motions

scholarly journals Relativistic and perspective effects in proper motions and radial velocities of stars

1986 ◽  
Vol 114 ◽  
pp. 193-198
Author(s):  
P. Stumpff
Keyword(s):  
Radial Velocity ◽  
Proper Motion ◽  
Additional Term ◽  
Radial Velocities ◽  
Proper Motions ◽  
Speed Of Light ◽  
Inertial Motion ◽  
Finite Speed ◽  
Numerical Example ◽  
Doppler Shifts

The heliocentric motion of stars is investigated by taking into account all effects due to the geometry and due to the finite speed of light. It is shown that the proper motions as given in star catalogues contain the main light retardation term; an additional term of this type modifies Schlesinger's (1917) term but is less significant than a 3rd order perspective term neglected in conventional astrometry. Kapteyn's star serves as a numerical example. The ambiguous relativistic relation between Doppler shifts and radial velocities is discussed and demonstrated in a diagram. The ambiguity is solved with rigorous equations which allow to compute the inertial motion of a star from its proper motion, classical radial velocity, and distance. -

scholarly journals Astrometric Distances of Globular Clusters

1988 ◽  
Vol 126 ◽  
pp. 523-524
Author(s):  
Kyle Cudworth ◽  
Ruth C. Peterson
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Proper Motion ◽  
Globular Clusters ◽  
Small Distance ◽  
Radial Velocities ◽  
Proper Motions ◽  
Velocity Dispersions

With high-precision radial velocities and proper motions, one can equate the proper motion and radial velocity dispersions to obtain astrometric distances independent of any standard candles. We discuss the method and the small distance it yields to M 22.

scholarly journals Proper motion of the spectrally selected structures in Herbig-Haro flows

2021 ◽  
pp. 495-501
Author(s):  
T. A. Movsessian ◽  
T. Yu. Magakyan
Keyword(s):  
Proper Motion ◽  
Physical Nature ◽  
Radial Velocities ◽  
Proper Motions ◽  
Low Velocity ◽  
Reverse Shock ◽  
Working Surface ◽  
Fabry Perot ◽  
Outflow System ◽  
Great Advance

We present some results of the investigations of proper motions of spectrally separated structures in the Herbig-Haro (HH) outflows with the aid of Fabry-Perot scanning interferometry. This project was started more than twenty years ago on the 2.6m telescope of Byurakan Observatory and afterwards was continued on 6m telescope (Russia). We describe the progress of research in the frames of this project and focus in more detail on the results of the latest observations of HH 83 outflow system. The method of Fabry-Perot scanning interferometry allowed to reveal the morphology of high and low velocity structures not only inside the terminal working surfaces of the jets but also in their internal knots. As the great advance we consider the development of a methodology for measuring proper motions of already separated kinematical structures using observations in two epochs, which made it possible to reveal the physical nature of these structures. Concerning the HH 83 collimated outflow it should be noted that our first observations of HH 83 revealed two structures in its working surface with strongly different radial velocities, and the second epoch data allowed to measure their proper motions. The proper motions of these structures are nearly equal, which points that they are physically connected and represents forward and reverse shock regions in the terminal working surface of HH 83.

scholarly journals Gaia DR2 reveals a very massive runaway star ejected from R136

2018 ◽  
Vol 619 ◽  
pp. A78 ◽  
Author(s):  
D. J. Lennon ◽  
C. J. Evans ◽  
R. P. van der Marel ◽  
J. Anderson ◽  
I. Platais ◽  
...  
Keyword(s):  
Lower Limit ◽  
Proper Motion ◽  
Evolutionary History ◽  
Massive Star ◽  
Position Angle ◽  
Proper Motions ◽  
Central Cluster ◽  
Dynamical Constraints ◽  
Runaway Stars ◽  
Gaia Dr2

A previous spectroscopic study identified the very massive O2 III star VFTS 16 in the Tarantula Nebula as a runaway star based on its peculiar line-of-sight velocity. We use the Gaia DR2 catalog to measure the relative proper motion of VFTS 16 and nearby bright stars to test if this star might have been ejected from the central cluster, R136, via dynamical ejection. We find that the position angle and magnitude of the relative proper motion (0.338±0.046 mas yr−1, or approximately 80±11 km s−1) of VFTS 16 are consistent with ejection from R136 approximately 1.5±0.2 Myr ago, very soon after the cluster was formed. There is some tension with the presumed age of VFTS 16 that, from published stellar parameters, cannot be greater than 0.9+0.3−0.2 Myr. Older ages for this star would appear to be prohibited due to the absence of He I lines in its optical spectrum, since this sets a firm lower limit on its effective temperature. The dynamical constraints may imply an unusual evolutionary history for this object, perhaps indicating it is a merger product. Gaia DR2 also confirms that another very massive star in the Tarantula Nebula, VFTS 72 (alias BI 253; O2 III-V(n)((f*)), is also a runaway on the basis of its proper motion as measured by Gaia. While its tangential proper motion (0.392±0.062 mas yr−1 or 93±15 km s−1) would be consistent with dynamical ejection from R136 approximately 1 Myr ago, its position angle is discrepant with this direction at the 2σ level. From their Gaia DR2 proper motions we conclude that the two ∼100 M⊙ O2 stars, VFTS 16 and VFTS 72, are fast runaway stars, with space velocities of around 100 km s−1 relative to R136 and the local massive star population. The dynamics of VFTS 16 are consistent with it having been ejected from R136, and this star therefore sets a robust lower limit on the age of the central cluster of ∼1.3 Myr.

scholarly journals Proper motions in the Galactic bulge: Plaut's window

2007 ◽  
Vol 3 (S245) ◽  
pp. 351-354
Author(s):  
Katherine Vieira ◽  
Dana Cassetti-Dinescu ◽  
René A. Méndez ◽  
R. Michael Rich ◽  
Terrence M. Girard ◽  
...  
Keyword(s):  
Proper Motion ◽  
Galactic Rotation ◽  
Red Giants ◽  
Proper Motions ◽  
Motion Study ◽  
Solar Motion ◽  
Two Samples ◽  
Red Clump ◽  
Good Agreement ◽  
Peak Value

AbstractA proper motion study of a field of 20′ × 20′ inside Plaut's low extinction window (l,b)=(0o, −8o), has been completed. Relative proper motions and photographicBVphotometry have been derived for ~ 21,000 stars reaching toV~ 20.5 mag, based on the astrometric reduction of 43 photographic plates, spanning over 21 years of epoch difference. Proper motion errors are typically 1 mas yr−1. Cross-referencing with the 2MASS catalog yielded a sample of ~ 8700 stars, from which predominantly disk and bulge subsamples were selected photometrically from theJHcolor-magnitude diagram. The two samples exhibited different proper-motion distributions, with the disk displaying the expected reflex solar motion. Galactic rotation was also detected for stars between ~2 and ~3 kpc from us. The bulge sample, represented by red giants, has an intrinsic proper motion dispersion of (σl, σb) = (3.39, 2.91)±(0.11, 0.09) mas yr−1, which is in good agreement with previous results. A mean distance of$6.37^{+0.87}_{-0.77}$kpc has been estimated for the bulge sample, based on the observedKmagnitude of the horizontal branch red clump. The metallicity [M/H] distribution was also obtained for a subsample of 60 bulge giants stars, based on calibrated photometric indices. The observed [M/H] shows a peak value at [M/H] ~ −0.1 with an extended metal poor tail and around 30% of the stars with supersolar metallicity. No change in proper motion dispersion was observed as a function of [M/H]. We are currently in the process of obtaining CCDUBV RIphotometry for the entire proper-motion sample of ~ 21,000 stars.

Investigation of relative motion in the triple system ADS 48 on the basis of Gaia DR2 and Pulkovo 26-inch refractor observations

2021 ◽  
pp. 89-98
Author(s):  
O. V. KIYAEVA ◽  
R. YA. ZHUCHKOV ◽  
I.S. IZMAILOV
Keyword(s):  
High Precision ◽  
Relative Motion ◽  
Apparent Motion ◽  
Triple System ◽  
Radial Velocities ◽  
Proper Motions ◽  
The Family ◽  
Outer Pair ◽  
Motion Parameters ◽  
Gaia Dr2

There are high-precision positions, proper motions, parallaxes and radial velocities at the instant 2015.5 for all three components of the star ADS 48 ABF in the catalogue Gaia DR2 (2018). According to these data relative motions and the family of orbits were calculated by the Apparent Motion Parameters (AMP) method (Kiselev and Kiyaeva, 1980), and the best orbit was chosen for the inner pair AB. A perturbation with the period of 11 years was discovered according to Pulkovo observations of the outer pair. The reasons for the perturbation are discussed.

scholarly journals Wading Through the Quagmire of Schmidt-Plate Coordinate Systematics

1998 ◽  
Vol 179 ◽  
pp. 384-385 ◽  
Author(s):  
C.-L Lu ◽  
I. Platais ◽  
T.M. Girard ◽  
V. Kozhurina-Platais ◽  
W.F. Van Altena ◽  
...  
Keyword(s):  
Proper Motion ◽  
San Juan ◽  
Proper Motions ◽  
Positional Accuracy

We attempted to quantify the magnitude-dependent systematics in a sample of Schmidt plates by comparison to positions from the Yale/San Juan Southern Proper Motion program which offers star positions and absolute proper motions down to B = 18 with a mean density of about 50 stars per square degree and a positional accuracy of 0.1″ (Platais et al. 1995).

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