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Merged catalogue of reflection nebulae
Several catalogues of reflection nebulae are merged to create a uniformcatalogue of 913 objects. It contains revised coordinates,cross-identifications of nebulae and stars, as well as identificationswith IRAS point sources.The catalogue is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/399/141
| Speckle Interferometry of New and Problem Hipparcos Binaries. II. Observations Obtained in 1998-1999 from McDonald Observatory
The Hipparcos satellite made measurements of over 9734 known doublestars, 3406 new double stars, and 11,687 unresolved but possible doublestars. The high angular resolution afforded by speckle interferometrymakes it an efficient means to confirm these systems from the ground,which were first discovered from space. Because of its coverage of adifferent region of angular separation-magnitude difference(ρ-Δm) space, speckle interferometry also holds promise toascertain the duplicity of the unresolved Hipparcos ``problem'' stars.Presented are observations of 116 new Hipparcos double stars and 469Hipparcos ``problem stars,'' as well as 238 measures of other doublestars and 246 other high-quality nondetections. Included in these areobservations of double stars listed in the Tycho-2 Catalogue andpossible grid stars for the Space Interferometry Mission.
| 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.
| CH(+) in the interstellar medium
This paper describes observations of interstellar CH(+) along the linesof sight to O and B stars with E(B-V)s up to +1.13. Along some lines ofsight with strong detections of CH(+), we find distinct radial velocityshifts between the CH(+) lines and other neutral species, such as Ca Iand CH. The shifts are small but are predicted by shock models of CH(+)formation in which the shock is inclined with respect to the observer.We have also found no column densities exceeding approximately1013.8/sq cm. When these data are examined along with theother CH(+) data collected from the literature, the previously seentendency of CH(+) column density to increase with E(B-V) does notcontinue beyond reddenings of about +0.6. These findings offer supportto the shock model of CH(+) formation for at least some lines of sight.
| An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
| LkH-alpha 198 and V 376 Cassiopeiae - Speckle interferometric and polarimetric observations of circumstellar dust
The circumstellar material close to the stellar sources is investigated,and its distribution and its relations to the general optical appearanceand the orientation of the molecular outflow are determined. Speckleobservations were carried out with a near-infrared speckleinterferometer between September 1986 and October 1989. LkH-alpha 198shows a complicated structure without clear alignment, and this is alsotrue on subarcsec (less than 1000 AU) scales. V 376 Cas appears to be abipolar nebula, seen nearly edge-on, oriented at position angle 120 deg.The orientations of LkH-alpha 198 and V 376 show no obvious relationswith the interstellar field direction. The near-infrared albedo ofcircumstellar dust is quite high both in the case of LkH-alpha 198 and V376 Cas, which indicates a larger particle size than typical forinterstellar dust.
| The compact star-forming regions associated with the Herbig Ae/Be stars LK H-alpha 198 and LK H-alpha 234
Photoelectric photometry and spectral classification are presented for19 stars in the region of Lk H-alpha 198 and 35 stars in the region ofLk H-alpha 234. Interstellar extinction in compact star-forming regionis compared with the CO emission map. It is found that the distance tothe Lk H-alpha 198 region is 630 + or - 30 pc. The distance to the LkH-alpha region is 1250 + or - 50 pc. The extensions of the regions are 2pc and 10 pc for Lk H-alpha 198 and 234, respectively. Also, the totalmasses of the regions are found to be 800 solar masses for Lk H-alpha198 and 2000 solar masses for Lk H-alpha 234. The light curve sectionsfor the regions and results of polarimetry for the stars in the LkH-alpha 234 region are given.
| A survey of ultraviolet objects
An all-sky survey of ultraviolet objects is presented together with astatistical analysis that leads to the conclusion that there is asignificantly higher population of hot subdwarfs lying below themain-sequence than hitherto thought. The distribution of all ultravioletobjects, main sequence ultraviolet objects, and MK unclassifiedultraviolet objects are shown in galactic coordinates, and the absolutemagnitudes and color-color diagrams for these groups are presented.Scale heights are derived, giving values similar to planetary nebulaefor the hottest groups.
| Molecular clouds associated with reflection nebulae. I - A survey of carbon monoxide emission
The paper presents 2.6 mm wavelength CO and (C-13)O observations of 130molecular clouds associated with reflection nebulae. Enhanced COemission was found in the vicinity of the illuminating star in abouthalf the objects studied. There is a tendency for the CO peak to beslightly displaced from the star. Many examples of peaks that appear toresult from heating of the cloud by the nearby star are found, whileothers appear to be associated with independent concentrations ofmaterial.
| Spectral classification and UBV H BET photometry.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977ApJ...213..105D&db_key=AST
| Stars in reflection nebulae
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968AJ.....73..233R&db_key=AST
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