An analysis of the AGK3 comparison star positions
Proper motions formed with the use of positions in the AGK3 and other, older catalogues are investigated for systematic trends.
Herget, P.↗
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G61-29, a helium emission-line star.
G61-29 is the first star discovered in which helium alone has been observed in emission. Three spectrograms of the star were obtained at the Lick 120-inch telescope. The most prominent spectral features in the blue region are the He I triplet lines at 4471, 4026, and 3889 A. All He I lines are extremely broad. The high proper motion of the star limits its maximum distance to about 200 pc or less if the star is gravitationally bound to the Galaxy.
Burbidge, E. M.↗
Concerning the planetary system of Barnard's Star.
Reanalyzed data pertaining to the proper motion of Barnard's Star indicate that at least two dark companions are required to explain the observations. It is found that the orbits of the two companions are not coplanar, but have a relative inclination of nearly 50 deg.
Black, D. C.↗
A photometric study of the Orion OB 1 association. 1: Observational data
An extensive catalog of observational data is presented for stars in the region of the young stellar association Orion OB 1. In addition to new photoelectric observations obtained on the uvbyB and UBV systems, photoelectric and spectroscopic data were compiled for the stars observed and for several bright members of the association having available photometric indices. Mean weighted values were computed for the uvbyB and UBV data and are tabulated in summary tables which include all references for individual values. These tables are expected to be reasonably complete for association members earlier than spectral type A0. From an analysis of currently available proper motion, radial velocity, and photometric data, membership criteria were derived and qualitative membership probabilities for 526 stars were summarized. A set of charts is included for assistance in identification of the program stars in all regions of the association.
Warren, W. H., Jr.↗
Space telescope optical telescope assembly/scientific instruments. Phase B: Preliminary design and program definition study. Volume 2A(3): Astrometry
Wide field measurements, namely, measurements of relative angular separations between stars over a relatively wide field for parallax and proper motion determinations, were made with the third fine guidance sensor. Narrow field measurements, i.e., double star measurements, are accomplished primarily with the area photometer or faint object camera at f/96. The wavelength range required can be met by the fine guidance sensor which has a spectral coverage from 3000 to 7500 A. The field of view of the fine guidance sensor also exceeds that required for the wide field astrometric instrument. Requirements require a filter wheel for the wide field astrometer, and so one was incorporated into the design of the fine guidance sensor. The filter wheel probably would contain two neutral density filters to extend the dynamic range of the sensor and three spectral filters for narrowing effective double star magnitude difference.
Source record↗
Differential radio astronomy of galactic objects
A differential astrometry technique is discussed. An improved proper motion and a parallax limit for pulsar 1929 + 10 is presented as well as a limit on the space velocity of the enigmatic object in SgrA.
Backer, D. C.↗
Documentation for the machine-readable version of the Perth 70: A catalogue of positions of 24900 stars tape B, mean values of the observation
The Perth 70 catalog contains accurate positions of 24978 stars, plus other useful data such as approximate proper motions, radial velocities, and parallaxes. The Perth 70 is a result of meridian circle observations made by the Hamburg observatory expedition to Perth as part of the international effort of Southern References Stars (SRS). Tape B, which contains mean values of the observations and corresponds to the printed catalog is described.
Warren, W. H., Jr.↗
On the computation of acceleration parallaxes
Rigorous formulas are derived with which one can compute from three observed (coplanar) directions the proper-motion components and the product of parallax and radial velocity of an object (star) which moves uniformly with respect to the observer (earth). The errors of the determination of distance by parallactic acceleration are analyzed and the possibility of determining distances by this method is discussed.
Eichhorn, H.↗
Evidence for extended X-ray emission from globular clusters
Deep exposures with the Einstein Observatory show evidence for diffuse X-ray emission from three globular clusters. One possible interpretation of these observations is that the interaction between a cluster wind and a hot gaseous galactic halo is being observed. The one cluster for which the proper motion has been measured is consistent with this interpretation.
Hartwick, F. D. A.↗
Discovery of carbon stars in the Draco dwarf spheroidal galaxy
A grating prism survey of the Draco dwarf spheroidal galaxy that is 97% areally complete has led to the discovery of three carbon stars. Membership of these stars in Draco is firmly established from luminosity, proper motion, and radial velocity considerations. Optical and preliminary infrared photometry suggest that the Draco carbon stars are more closely related to the CH stars in omega Cen than to the luminous carbon stars found in the Fornax and Carina dwarfs. One of the carbon stars possesses an unusual emission line spectrum which might be indicative of either a very hot degenerate companion or a preplanetary evolutionary stage. Carbon stars have now been located in all four of the dwarf spheroidals that have been examined using transmission grating prism techniques. The rarity of these stars in galactic globulars, systems with which the dwarf spheroidals are often compared, indicates a fundamental population difference whose cause is not yet fully understood.
Aaronson, M.↗
Observations of dynamical phenomena in sunspots
A preliminary report of the results of one observing run based on data from one spectral line, the photospheric magnetic line Fe 6303, is presented as part of a series of observations of dynamical phenomena in sunspots using photographic spectra with the SPO vacuum tower telescope and echelle spectrograph. The ejection of a magnetic feature from the outer edge of the penumbra was observed. The initial total field strength of the feature was about 1000 gauss, which appeared to decrease as the feature moved away from the sunspot. The proper motion was about 2 km/s, and the velocity field measured in the V profile showed a downflow of 400 m/s on the spotward side of the moving magnetic feature. Umbral oscillations at the photospheric level with a herringbone structure characteristic of horizontally propagating waves, suggesting some overtone mode of membrane oscillation in the umbra, were seen. The peak amplitude of the oscillation was about 200 m/s, and the mean power spectrum had several clear peaks.
Nye, A. H.↗
The exciting stars of Herbig-Haro objects
Accurate astrometry and infrared photometry are presented for 16 objects that are believed to represent the exciting stars for Herbig-Haro (HH) objects in their vicinities. These identifications are made on the bases of steeply rising energy distributions, proper motions of HH objects, alignment of sources with HH objects, or far-infrared emission. Exciting stars for the following HH objects are newly discovered or recognized: HH 17; HH 31; HH 32; HH 33 and 40; HH 34; HH 38 and 43; HH group 14 in NGC 2264; RNO 40; RNO 43; and GGD 33a, 33b, and 35. Geometrical alignments of some sources with HH objects support the view that young stars are capable of channeling kinetic energy into small solid angles, as does the fact that some sources are slightly displaced from the apices of fan nebulae (HH 17, R Mon, Haro 6-10). These exciting stars span a wide range of bolometric luminosity, although all are likely to be very young.
Cohen, M.↗
A search for Earth-crossing asteroids, supplement
The ground based electro-optical deep space surveillance program involves a network of computer controlled 40 inch 1m telescopes equipped with large format, low light level, television cameras of the intensified silicon diode array type which is to replace the Baker-Nunn photographic camera system for artificial satellite tracking. A prototype observatory was constructed where distant artificial satellites are discriminated from stars in real time on the basis of the satellites' proper motion. Hardware was modified and the technique was used to observe and search for minor planets. Asteroids are now routinely observed and searched. The complete observing cycle, including the 2"-3" measurement of position, requires about four minutes at present. The commonality of asteroids and artificial satellite observing, searching, data reduction, and orbital analysis is stressed. Improvements to the hardware and software as well as operational techniques are considered.
Taff, L. G.↗
Submilliarcsecond VLBI Observations of the Close Pair GC 1342+662 and GC 1342+663
Differential VLBI was simultaneously performed on the source pair GC 1342+662 and GC 1342+663 (4.4-arcminute separation) using S-band on the Goldstone/Madrid baseline. These measurements were acquired on two separate observing sessions: 30 December 1982 and 14 May 1983. The change in separation of GC 1342+662 relative to GC 1342+663 between the two epochs was 0.03 + or 0.08 milliarcsecond. The differences of the relative position measurements between epochs of GC 1342+662 relative to GC 1342+663 were -0.29 + or - 0.05 milliarcsecond in right ascension and 0.14 + or - 0.09 milliarcsecond in declination. These measurements demonstrate submilliarcsecond accuracy and repeatability. The discrepancies outside of the formal uncertainties could be attributed to the intrinsic properties of the sources such as structure and to a lesser probability, proper motion. These discrepancies could also be attributed to excursions in UT1-UTC of about four times the quoted BIH uncertainty.
Morabito, D. D.↗
Astrometry
Progress in astrometry is reviewed. Aspects of photographic astrometry are addressed, including the use and optimization of emulsions as detectors and the application of side-field and long-focus photographic astrometry to the determination of stellar positions, to proper motion surveys, the determination of more accurate parallaxes, the study of binaries, and the examination of the membership and internal motions of star clusters. The advantages and disadvantages of photoelectric astrometry are summarized, and the instruments used in this field is discussed, including scanners, detector arrays, stellar interferometers, space telescopes, and satellites. Promising observational methods for studying binary stars are addressed. Astrometry derived from meridian circle observations is considered, emphasizing the FK4 system. The use of radio astrometry is briefly discussed.
Van Altena, W. F.↗
Radio stars - A possible link between the Hipparcos optical reference frame and an extra-galactic very long baseline interferometry reference frame
The concept of typing the Hipparcos optical and the JPL VLBI frames of reference by means of VLBI measurements of the positions and proper motions of the radio components of some bright stars is considered. The properties of the thermal and non-thermal radio-stars are discussed and 22 candidate stars are selected to achieve this tie. A description is given of the first VLBI attempt to detect these stars on the intercontinental baselines of the Deep Space Network with the Mark II recording system.
Lestrade, J.-F.↗
On the origin of delta spots
Mount Wilson sunspot drawings from 1966 through 1980 were used in conjunction with H-alpha filtergrams from Big Bear Solar Observatory to examine the origin of delta spots, spots with bipolar umbrae within one penumbra. Of the six cases studied, five were formed by the union of non-paired spots. They are either shoved into one another by two neighboring growing bipoles or by a new spot borne piggy-back style on an existing spot of opposite polarity. Proper motions of the growing spots take on curvilinear paths around one another to avoid a collision. This is the shear motion observed in delta spots (Tanaka, 1979). In the remaining case, the delta spot was formed by spots that emerged as a pair. The findings indicate no intrinsic differences in the formation or the behavior between delta spots and spots of normal magnetic configuration.
Tang, F.↗
A high-resolution study of Herbig-Haro objects 1 and 2
Observations have been conducted of Herbig-Haro objects 1 and 2 with high spectral and spatial resolution in order to test shock models for the line emission. A detailed bow shock model has been constructed which yields line widths and optical and UV spectra in reasonable agreement with observation for maximum shock velocities approximately 200 km/s. Such velocities are comparable to the transverse velocities of the knots in HH 1 and 2 inferred from proper motion studies. The observations suggest that HH objects are rapidly moving, dense clouds shocking with less dense interstellar medium. The large energy requirements of these objects, combined with their small apparent size as seen from the exciting star, seem to require unreasonably large stellar mass loss rates. However, it is possible that the HH objects subtended a much larger solid angle at the star when originally accelerated.
Hartmann, L.↗