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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
| Far-Ultraviolet (912--1900 Angstrom ) Energy Distribution in Early-Type Main-Sequence Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...449..280C&db_key=AST
| A Study of the Kinematics of the Local Dark Clouds
Not Available
| CCD observations of diffuse interstellar bands in reflection nebulae
CCD spectra of 59 stars have been obtained in order to measure diffuseband strengths between 5690 and 5870 A. Most (37) off the stars are inreflection nebulae, and the rest are relatively unreddened comparisonstars. The pixel spacing corresponds to 0.2 A, and the signal-to-noise(S/N) ratio ranges from 60 up to 600. Six diffuse bands are measurablein the data: 5705, 5778, 5780, 5797, 5844, and 5849 A. Based on thedegree of correlation between the bands in pairs, as well as with E(B-V)and the 2175 A extinction bump, the bands can be divided into threegroups. The first one consists of the narrow bands at 5780, 5797, and5849 A. The second group contains the broad bands at 5778 and 5844 A,while 5705 A lies in between these groups in terms of correlationbehavior. The second group correlates very badly with E(B-V), and thevery broad 5778 A band is the only one that shows a very goodcorrelation with the 2175 A bump.
| BVR observations of polarization parameters of stars in reflection nebulas
The observed polarizations of the nuclei of reflection nebulas and fieldstars in B, V, R filters are given. A connection has been found betweenthe direction of the polarization vector, the structure of thereflection nebula, and the shape of the cloud in which the nebula issituated. The direction of the plane of polarization for stars seenthrough the filamentary structure of a nebula is the same as thedirection of the filaments. Stars situated at the edges of clouds andchannels have direction of the polarization vector the same as theapparent boundary of the cloud.
| Optical observations of ultraviolet objects. II - Classification and photometry /l = 0 to 145 deg/
UBV photometry and MK spectral classification are presented for a sampleof stars originally selected as UV objects from satellite photometrywith the S2/68 experiment. Although most stars of the sample arespectroscopically normal, a number of hot, subluminous stars were alsofound. Radial velocities are given for some of the stars observed. It isproposed that the majority of the apparently normal early B stars athigh galactic latitudes which are not runaway stars are subluminousdisc-population analogues of horizontal branch B stars of Population II.
| Polarization of stars in R-associations - Observational data
Polarimetric data are assembled for 95 stars that are illuminatingreflection nebulae. Most of these belong to 18 standard R-associations.The observed dependence of the percentage polarization P on wavelengthand color excess E(B-V) suggest that the unpolarized light ofR-association members may become polarized as it traverses an ensembleof dust grains aligned by a magnetic field which in some cases (Tau R2,Ori R1/R2, Sco R1, Cep R2) is intrinsic to the association. In certainR-associations the grain size is variable and the stochastic magneticfield component fluctuates on a scale of 10-30 pc.
| A survey of interstellar neutral potassium. I - Abundances and physical conditions in clouds toward 188 early-type stars
Observations of interstellar absorption in the resonance doublet 7664,7698 A of neutral potassium toward 188 early-type stars at a spectralresolution of 8 km/s are reported. The 7664 A line is successfullyseparated from nearly coincident telluric O2 absorption for all but afew of the 165 stars for which K I absorption is detected, makingpossible an abundance analysis by the doublet ratio method. Therelationships between the potassium abundances and other atomicabundances, the abundance of molecular hydrogen, and interstellarreddening are investigated.
| R associations. VI - The reddening law in dust clouds and the nature of early-type emission stars in nebulosity from a study of five associations
Positions, identification charts, UBVRIKLMN photometry and spectraltypes are given for stars, illuminating reflection nebulae that arevisible on the POSS prints, which have been identified in fiveassociations. With a ratio of total to selective extinction of 4.2, thereddening law applicable to the dust clouds in which the stars areembedded is steeper than normal. The five associations exhibit 18early-type stars with circumstellar shells, of which those with spectraltypes earlier than B5 characteristically have weak IR excesses, incontrast to the strong excesses indicative of circumstellar dust, oflater-type stars. Color-magnitude charts show a distribution lying abovethe ZAMS by up to about 2 mag for both the circumstellar shell stars andthose classified as rapid rotators. It is suggested that (1) rapidrotation accounts for the scatter in the color-magnitude diagram, and(2) many of the nebulous early-type emission-line stars are rapidrotators rather than pre-main sequence objects.
| 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.
| The differential blanketing of the main-sequence and near-main-sequence M67 stars relative to the Hyades and Coma
The blanketing of main-sequence stars in the Hyades, Coma, and M67, andof F subgiants in M67 is compared on the basis of red photometry. Therequired reddening corrections are derived by several techniques thatare insensitive or probably insensitive to blanketing. The meanreddening values obtained are E(B-V) of approximately 0.016 for theHyades, 0.006 for Coma, and 0.053 for M67. These reddening values areshown to imply that there is measurable reddening well inside 100 pc,that Crawford's (1975) A- and F-star relations must be slightly revised,that significant numbers of relatively nearby field A stars are slightlyreddened, that the North Galactic Pole stars of Hilditch et al. (1976)are reddened by 0.01 to 0.03 in B-V, and that Hyades-field F-star b-ycomparisons must be revised. It is found from the reddening-correctedphotometry that: (1) the differential Hyades-M67 blocking is greater inabsolute value for early G late F stars; (2) effects of evolution on theF IV stars in M67 are clearly discernible in the UV and marginally so inB-V; and (3) the F stars on and very near the M67 main sequence haveapproximately the Coma blocking and considerably less than the Hyadesblocking, which indicates that the zero-age metallicity of M67 issolar-normal.
| CO observations of galactic reflection nebulae
Carbon monoxide emission has been observed toward about 35 galacticreflection nebulae. The peaking of CO temperatures near the hotter starsindicates substantial local heating of the gas and dust by the embeddedstars. Wide low-level emission wings are seen on several of the (C-12)Oline profiles; these are most plausibly interpreted as due to cloudmaterial accelerated by such processes as radiation pressure from thenewborn stars.
| Stars in reflection nebulae
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968AJ.....73..233R&db_key=AST
| A study of reflection nebulae.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966AJ.....71..990V&db_key=AST
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Лисичка |
| Прямое восхождение: | 19h26m11.32s |
| Склонение: | +22°45'26.3" |
| Видимая звёздная величина: | 8.622 |
| Расстояние: | 892.857 парсек |
| Собственное движение RA: | 1.2 |
| Собственное движение Dec: | -6.6 |
| B-T magnitude: | 8.777 |
| V-T magnitude: | 8.635 |
Каталоги и обозначения:
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