Commotion in their Motions: Proper Motion Anomalies of Nearby AGB Stars
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Michele Woodland↗
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Proper motion survey with the 48-inch Schmidt telescope. 30: Proper motions for 1357 faint stars
A catalog of the proper motion of the faint stars and associated data is presented.
Luyten, W. J.↗
Proper motion survey with the forty-eight inch Schmidt telescope. 33: Proper motions for 3478 faint stars
Data for the motions of 3478 stars are presented. The data were obtained with the automated-computerized plate scanner and measuring machine. Only data for those stars for which no earlier determination of proper motions are included.
Luyten, W. J.↗
Joint Survey Processing. II. Stellar Proper Motions in the COSMOS Field from Hubble Space Telescope ACS and Subaru Telescope HSC Observations
We analyze stellar proper motions in the COSMOS field to assess the presence of bulk motions. At bright magnitudes (G-band 18.5–20.76 AB), we use the proper motions of 1010 stars in the Gaia DR2 catalog. At the faint end, we compute proper motions of 11,519 pointlike objects at i-band magnitudes 19–25 AB using Hubble ACS and Subaru HSC data, which span two epochs about 11 yr apart. In order to measure these proper motions with unprecedented accuracy at faint magnitudes, we developed a foundational set of astrometric tools that will be required for joint survey processing of data from the next generation of optical/infrared surveys. The astrometric grids of Hubble ACS and Subaru HSC mosaics were corrected at the catalog level using proper motion–propagated and parallax-corrected Gaia DR2 sources. These astrometric corrections were verified using compact extragalactic sources. Upon comparison of our measured proper motions with Gaia DR2, we estimate the uncertainties in our measurements to be ~2–3 mas yr –1 axis –1 , down to 25.5 AB mag. We correct proper motions for the mean motion of the Sun, and we find that late-type main-sequence stars predominantly in the thin disk in the COSMOS field have space velocities mainly toward the Galactic center. We detect candidate high-velocity (≥220 km s –1 ) stars, six of them at ~0.4–6 kpc, from the Gaia sample, and five of them at ~20 kpc, from the faint star HSC and ACS sample. The sources from the faint star sample may be candidate halo members of the Sangarius stream.
79 ASTRONOMY AND ASTROPHYSICS↗
Revised and New Proper Motions for Confirmed and Candidate Milky Way Dwarf Galaxies
A new derivation of systemic proper motions of Milky Way satellites is presented and applied to 59 confirmed or candidate dwarf galaxy satellites using Gaia Data Release 2. This constitutes all known Milky Way dwarf galaxies (and likely candidates) as of 2020 May, except for the Magellanic Clouds, the Canis Major and Hydra 1 stellar overdensities, and the tidally disrupting Bootes III and Sagittarius dwarf galaxies. We derive systemic proper motions for the first time for Indus 1, DES J0225+0304, Cetus 2, Pictor 2, and Leo T, but note that the latter three rely on photometry that is of poorer quality than that of the rest of the sample. We cannot resolve a signal for Bootes 4, Cetus 3, Indus 2, Pegasus 3, or Virgo 1. Our method is inspired by the maximum likelihood approach of Pace & Li and examines simultaneously the spatial, color–magnitude, and proper motion distribution of sources. Systemic proper motions are derived without the need to identify confirmed radial velocity members, although the proper motions of these stars, where available, are incorporated into the analysis through a prior on the model. The associated uncertainties on the systemic proper motions are on average a factor of ∼1.4 smaller than existing literature values. Analysis of the implied membership distribution of the satellites suggests that we accurately identify member stars with a contamination rate lower than 1 in 20.
79 ASTRONOMY AND ASTROPHYSICS↗
Quasars with large proper motions: A selection from the LQAC-5 catalogue combined with Gaia EDR3: Focusing on astrometric and photometric properties
Thanks to the cross-identification between the Gaia EDR3 (E-Data Release 3) catalogue and the quasars’ compiled catalogue LQAC-5 (Large Quasar Astrometric Catalogue-5), accurate astrometric parameters as well as photometric measurements were available for a set of 416 113 quasars. After analysing the astrometric and photometric properties of these quasars, we concentrate our study on objects characterized by significant proper motion, which contradicts the postulate that they are fixed in the celestial sphere. We derived statistical properties of the positions, parallaxes, and proper motions of the quasars cross-matched with Gaia EDR3. We carried out a specific investigation of quasars with a proper motion larger than 10 mas yr -1 , and used colour-colour diagrams in mid-infrared to discriminate these quasars from stellar contamination. We discuss, in detail, a few cases where the abnormal proper motion could be caused by misidentifications. We note that 43% of LQAC-5 quasars were not detected by Gaia EDR3, mainly because of the cut-off magnitude at G = 21. The comparison between r(G) (Gaia) and r (SDSS) shows a normal distribution. The normalized distributions of parallaxes and proper motions are identical to that of the Gaia CRF2, as well as the distribution of the G BP -G RP colour index. We have identified 937 LQAC-5 objects (0.27% of the sample) with Gaia EDR3 proper motion which is significant at the 5σ level. We have clearly shown that below z = 0.35, the integrated magnitude G(r) obtained from SDSS spectra is smaller than G (Gaia), leading to the statement that the quasars are generally resolved under this threshold, which should lead to a bad determination of proper motion. Moreover, to discriminate quasars from stellar contamination, we have plotted them in a mid-infrared colour–colour diagram. Finally, we have made a final selection of 41 objects with μ > 10 mas yr -1 , satisfying drastic constraints, which makes them potential candidates for considering their proper motion as real. In this paper we carried out a complete analysis of the quasars of the LQAC-5 which were cross-identified with Gaia EDR3 ; this serves as an alternative and complementary study with respect to Gaia CRF2, involving a different population of quasars. We selected a set of 41 quasars with a proper motion exceeding 10 mas yr -1 , which can be considered as very high for objects which are a priori fixed in the celestial sphere.
79 ASTRONOMY AND ASTROPHYSICS↗
Quasars with Proper Motions and the Link to Double and Multiple AGNs
Gaia used a large sample of photometrically selected active galactic nuclei (AGNs) and quasars to remove the residual spin of its global proper motion system in order to achieve a maximally inertial reference frame. A small fraction of these reference objects have statistically significant astrometric proper motions in Gaia EDR3. We compile a source sample of 105,593 high-fidelity AGNs with accurate spectroscopically determined redshifts above 0.5 from the SDSS and normalized proper motions below 4. The rate of genuinely perturbed proper motions is at least 0.17%. A smaller high completeness sample of 152 quasars with excess proper motions at a confidence level of 0.9995 is examined in detail. Pan-STARRS images and Gaia-resolved pairs reveal that 29% of the sample are either double sources or gravitationally lensed quasars. An Anderson–Darling test on parameters of a smaller high-reliability sample and their statistical controls reveals 17 significant factors that favor multiplicity and multi-source structure as the main cause of perturbed astrometry. Using a nearest-neighbor distance statistical analysis and counts of close companions in Gaia on a much larger initial sample of AGNs, an excess of closely separated sources in Gaia is detected. At least 0.33% of all optical quasars are genuinely double or multiply imaged. We provide a list of 44 candidate double or multiple AGNs and four previously known gravitational lenses. Many proper motion quasars may be more closely separated, unresolved doubles exhibiting the variability imposed motion effect, and a smaller fraction may be chance alignments with foreground stars causing weak gravitational lensing.
Astrometric microlensing effect↗
The Solar Neighborhood. XXV. Discovery of New Proper Motion Stars with 0.40 sec/yr > mu > or = 0.18 sec/yr Between Declinations -47 deg and 00 deg
We present 2817 new southern proper motion systems with 0.40 sec/yr > mu > or = 0.18 sec/yr and declination between 47 deg and 00 deg. This is a continuation of the SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky. We use the same photometric relations as previous searches to provide distance estimates based on the assumption that the objects are single main-sequence stars. We find 79 new red dwarf systems predicted to be within 25 pc, including a few new components of previously known systems. Two systems--SCR 1731-2452 at 9.5 pc and SCR 1746-3214 at 9.9 pc--are anticipated to be within 10 pc. We also find 23 new white dwarf (WD) candidates with distance estimates of 15-66 pc, as well as 360 new red subdwarf candidates. With this search, we complete the SCR sweep of the southern sky for stars with mu > or = 0.18 sec/yr and R(sub 59F) < or = 16.5, resulting in a total of 5042 objects in 4724 previously unreported proper motion systems. Here we provide selected comprehensive lists from our SCR proper motion search to date, including 152 red dwarf systems estimated to be within 25 pc (9 within 10 pc), 46 WDs (10 within 25 pc), and 598 subdwarf candidates. The results of this search suggest that there are more nearby systems to be found at fainter magnitudes and lower proper motion limits than those probed so far.
LOW MASS STARS↗
Halo common proper motion stars - Subdwarf distance scale, halo binary fraction, and UBVRI colors
Common proper motion stars identified by Luyten (1979, 1980) were selected according to reduced proper motion and photometric criteria to produce a list of candidate halo objects. UBVRI photometry was obtained to identify genuine halo parts. About 20 percent of the stars with (Fe/H) less than -1.0 were found to have random errors not less than several x 0.1 mag in distance modulus, in addition to the photometric errors, thought to be due to the existence of close binary companions to some of the common proper motion stars. The implications of these errors for kinematic studies of field Population II stars are considered. Systematic errors of order 16 percent were also detected in distances derived from the U-B,B-V deblanketing technique. It is suggested that Population II field stars did not originate in globular clusters which subsequently disintegrated but formed in less dense environments. Several K subdwarfs were found with very high UV excesses, comparable with those predicted by some synthetic colors.
Ryan, Sean G.↗
A Quantitative Analysis of Systematic Differences in the Positions and Proper Motions of Gaia DR2 with Respect to VLBI
We have analysed the differences in positions of 9081 matched sources between the GaiaData Release 2 (DR2) and very long baseline interferometry (VLBI) catalogues. The medianposition uncertainty of matched sources in the VLBI catalogue is a factor of two larger thanthe median position uncertainty in Gaia DR2. There are 9 per cent matched sources withstatistically significant offsets between both catalogues. We found that the reported positionalerrors should be rescaled by a factor of 1.3 for VLBI and 1.06 for Gaia and, in addition, the Gaiaerrors should be multiplied by the square root of chi squared per degree of freedom in order tobest fit the normalized position differences to the Rayleigh distribution. We have establishedthat the major contributor to statistically significant position offsets is the presence of opticaljets. Among the sources for which the jet direction was determined, the position offsets areparallel to the jet directions for 62 per cent of the outliers. Among the matched sources withsignificant proper motion, the fraction of objects with proper motion directions parallel tojets is a factor of three greater than on average. Such sources have systematically higher chisquared per degree of freedom. We explain these proper motions as a manifestation of thesource position jitter caused by flares, which we predicted earlier. Therefore, the assumptionthat quasars are fixed points, and thus that differential proper motions determined with respectto quasar photocentres can be regarded as absolute proper motions, should be treated withgreat caution.
Petrov, L.↗
The Proper Motion of the Central Compact Object RX J0822-4300 in the Supernova Remnant Puppis A
Using the High Resolution Camera (HRC) aboard the Chandra X-ray Observatory, we have re-examined the proper motion of the central compact object RX J0822-4300 in the supernova remnant Puppis A. New data from 2010 August, combined with three archival data sets from as early as 1999 December, provide a baseline of 3886 days (more than 10 1/2 years) to perform the measurement. Correlating the four positions of RX J0822-4300 measured in each data set implies a projected proper motion of mu = 71 +/- 12 mas/yr. For a distance of 2 kpc this proper motion is equivalent to a recoil velocity of 672 +/- 115 km/s. The position angle is found to be 244 +/- 11 degrees. Both the magnitude and direction of the proper motion are in agreement with RX J0822-4300 originating near the optical expansion center of the supernova remnant. For a displacement of 371 +/- 31 arcsec between its birth place and today's position we deduce an age of (5.2 +/- 1.0) 10(exp 3) yrs for RX J0822-4300. The age inferred from the neutron star proper motion and filament motions can be considered as two independent measurements of the same quantity. They average to 4450 +/- 750 yrs for the age of the supernova remnant Puppis A.
Becker, Werner↗
X-ray Proper Motions and Shock Speeds along the Northwest Rim of SN1006
We report the results of an X-ray proper motion measurement for the NW rim of SN 1006, carried out by comparing Chandra observations from 2001 and 2012. The NW limb has predominantly thermal X-ray emission, and it is the only location in SN 1006 with signi cant optical emission: a thin, Balmer-dominated lament. For most of the NW rim, the proper motion is approximately equal to 0.30"yr(exp -1), essentially the same as has been measured from the H alpha lament. Isolated regions of the NW limb are dominated by nonthermal emission, and here the proper motion is much higher, 0:49"yr(exp -1), close to the value measured in X-rays along the much brighter NE limb, where the X-rays are overwhelmingly nonthermal. At the 2.2 kpc distance to SN 1006, the proper motions imply shock velocities of approximately 3000 kms(exp -1) and approximately 5000 kms(exp -1) in the thermal and nonthermal regions, respectively. A lower velocity behind the H alpha filament is consistent with the picture that SN 1006 is encountering denser gas in the NW, as is also suggested by its overall morphology. In the thermally-dominated portion of the X-ray shell, we also see an o set in the radial profiles at different energies; the 0.5-0.6 keV peak dominated by O VII is closer to the shock front than that of the 0.8-3 keV emission|due to the longer times for heavier elements to reach ionization states where they produce strong X-ray emission.
Katsuda, Satoru↗
Absolute proper motions of distant Galactic satellites
We describe the motivation for a new program to determine the absolute proper motions (transverse velocities) for distant Galactic globular clusters and satellite dwarf spheroidal galaxies. The topic of globular-cluster proper motions is reviewed with emphasis on the correction from relative to absolute proper motions. Our project relies on astrometry from deep 2-5 m prime focus plates which contain images of numerous faint galaxies which are used to set a precise extragalactic reference frame. We discuss first results from the survey, determinations of the space motions for the clusters Palomar 5 and Palomar 3, at distances of 21 and 88 kpc, respectively.
Majewski, S. R.↗
On the separations of common proper motion binaries containing white dwarfs
It is expected, on the basis of proper motion and estimated colors, that over 500 known common proper motion binaries (CPMBs) contain at least one white dwarf (WD) component, usually paired with a late type main sequence (MS) star. This paper examines 210 probable MS + MS and 26 probable WD + MS pairs from the LDS catalog to determine whether significant orbital expansion occurred as a consequence of the post-MS mass loss expected to accompany the formation of WDs in the CPMBs. It was found that, in the WD + MS pairs, the physical separation is nearly twice that in the MS + MS pairs.
Oswalt, T. D.↗
The proper motion of Herbig-Haro Objects. IV - RNO 40 and 43
Proper motions and spectra of the Herbig-Haro Objects RNO 40 and 43 have been obtained. The proper-motion vectors point away from far-infrared sources. The spectra were used to infer shock velocities. These shock velocities agree with the tangential motion in the case of RNO 40, but are smaller than the tangential motion in the case of RNO 43. RNO 43 appears to be associated with an entire family of comoving knots.
Jones, B. F.↗
The First X-Ray Proper-Motion Measurements of the Forward Shock in the Northeastern Limb of Sn 1006
We report on the first X-ray proper-motion measurements of the nonthermally-dominated forward shock in the northeastern limb of SN 1006, based on two Chandra observations taken in 2000 and 2008. We find that the proper motion of the forward shock is about 0.48"/yr and does not vary around the rim within the approx.10% measurement uncertainties. The proper motion measured is consistent with that determined by the previous radio observations. The mean expansion index of the forward shock is calculated to be approx..0.54 which matches the value expected based on an evolutionary model of a Type Ia supernova with either a power-law or an exponential ejecta density profile. Assuming pressure equilibrium around the periphery from the thermally-dominated northwestern rim to the nonthermally-dominated northeastern rim, we estimate the ambient density to the northeast of SN 1006 to be approx..0.085/cu cm.
Katsuda, Satoru↗
The positions and proper motions of HZ Herculis and 12 neighboring stars
The positions and proper motions of HZ Her, the optical counterpart of the X-ray source Her X-1, and 12 field stars are determined in the system of the FK4. The proper motion of HZ Her is consistent with that expected for an object with a relatively low peculiar velocity located at the approximate 3-kpc distance estimated for Her X-1.
Gatewood, G.↗
The origin and goals of the automated stellar proper motion survey
The historical background of the automation of the stellar proper motion survey is traced from its beginnings to the taking of the series of plates with the 48 inch Schmidt telescope at Mount Palomar covering 77% of the sky with 936 plates. The design goal for the automation is the documentation of the proper motions of stars from tenth through twentieth red magnitude. A typical scanning time for a pair of 14 inch star plates is projected to be about 45 minutes with the total processing time estimated at between one and two years for the complete set of plates.
Luyten, W. J.↗