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Speckle Interferometry of New and Problem HIPPARCOS Binaries
The ESA Hipparcos satellite made measurements of over 12,000 doublestars and discovered 3406 new systems. In addition to these, 4706entries in the Hipparcos Catalogue correspond to double star solutionsthat did not provide the classical parameters of separation and positionangle (rho,theta) but were the so-called problem stars, flagged ``G,''``O,'' ``V,'' or ``X'' (field H59 of the main catalog). An additionalsubset of 6981 entries were treated as single objects but classified byHipparcos as ``suspected nonsingle'' (flag ``S'' in field H61), thusyielding a total of 11,687 ``problem stars.'' Of the many ground-basedtechniques for the study of double stars, probably the one with thegreatest potential for exploration of these new and problem Hipparcosbinaries is speckle interferometry. Results are presented from aninspection of 848 new and problem Hipparcos binaries, using botharchival and new speckle observations obtained with the USNO and CHARAspeckle cameras.
| Spectral classifications in the near infrared of stars with composite spectra. III. Study of a sample of 137 objects with the Aurelie spectrograph
We provide spectral classifications for a sample of 137 stars mentionedas having composite spectra. The classifications were carried out on 33Angstroms /mm spectra in the region 8370 - 8870 Angstroms. Of these 137objects, 115 correspond in the infrared to cool stars (G, K or M) ofluminosity classes III, II and I; for 22 stars, we find only hot spectraof types B, A, F or Am, so that they do not fulfil our definition ofcomposite spectra. We detect four new Am stars, and one Am star (HD70826) turns out to be a composite spectrum object. As in Paper II, thecool components of composite spectra show a strong concentration in thevicinity of G8III. Based upon observations carried out at Observatoirede Haute-Provence (OHP).
| Interstellar Reddening in the Southern Hemisphere. II. Analysis of the uvby-Beta Observations
Photometric color excesses and distances plus heliocentric coordinatesare calculated for 3,762 southern A and early F stars. The presentresults, combined with those previously published for the northernhemisphere, complete the coverage of the spatial distribution ofinterstellar reddening in the entire solar neighborhood. The newreddening maps show that the interstellar matter within 300 pc of theSun forms a single very large cloud complex that is somewhatasymmetrical with respect to both the galactic center and the galacticplane. This complex is characterized by pronounced local irregularitiesin both density and spatial extent. The observations further indicatethat (1) the cloud complex is not associated with Gould's belt; (2)there exist large regions of the sky devoid of dust; (3) interstellarreddening is negligible at the galactic poles; (4) the role ofintercloud dust in the southern hemisphere; (5) the Sun is not locatedin a dust-free, spherically symmetric bubble as previously thought; and(6) the Sun is, however, located in an elongated dust-free region knownas the "local trough.". (SECTION: Interstellar Medium and Nebulae)
| The light curve of CV Serpentis, the sometimes-eclipsing Wolf-Rayet star
New photoelectric observations of the B-magnitude of CV Ser made in 1973and 1974 show no clear evidence of an eclipse, but they establishnight-to-night variability of several percent, a systematic brightnesschange of 0.035 mag during a portion of the single orbit observed in1973, and irregular flaring in 1974. We made iris photometermeasurements of Harvard patrol plates taken between 1905 June and 1953July, and find no evidence of a very deep eclipse such as observed byHjellming and Hiltner. We present several new light curves and discussthen in the light of the recent results of Cowley et al.
| A survey of stars with composite spectra.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Yilan |
| Sað Açýklýk: | 18h19m37.17s |
| Yükselim: | -10°56'00.5" |
| Görünürdeki Parlaklýk: | 8.011 |
| Uzaklýk: | 490.196 parsek |
| özdevim Sað Açýklýk: | 5.2 |
| özdevim Yükselim: | -3.1 |
| B-T magnitude: | 9.54 |
| V-T magnitude: | 8.138 |
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