FU Orionis: A Binary Star?
By using the Adaptive Optics with a Laser for Astronomy system at the3.6 m telescope of the Calar Alto Observatory, we detected a faint redstar in the apparent vicinity of FU Ori, the prototype of the FUoroutburst stars. Independent confirmation of the detection is obtainedfrom archival Probing the Universe with EnhancedOptics/Canada-France-Hawaii Telescope images. The separation between thecompanion candidate and FU Ori is 0.50", and their brightness contrastis around 4 mag. We discuss the possible nature of the newly detectedstar based on near-infrared photometry and its proper motion relative toFU Ori. The photometric data are consistent with a nearby late-typemain-sequence star, a background giant star, and a pre-main-sequencestar. On the basis of the proper motion and the stellar surface densityin the direction toward FU Ori, we argue that the probabilities of thefirst two options are very low.
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Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions
The FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over a longinterval of time and summarized mainly in the FK5. Part III of the FK6(abbreviated FK6(III)) contains additional fundamental stars with directsolutions. Such direct solutions are appropriate for single stars or forobjects which can be treated like single stars. Part III of the FK6contains in total 3272 stars. Their ground-based data stem from thebright extension of the FK5 (735 stars), from the catalogue of remainingSup stars (RSup, 732 stars), and from the faint extension of the FK5(1805 stars). From the 3272 stars in Part III, we have selected 1928objects as "astrometrically excellent stars", since their instantaneousproper motions and their mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,354 of the stars in Part III are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives, in addition to the SI mode, the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(III) proper motion in the single-star mode is 0.59 mas/year. This isa factor of 1.34 better than the typical HIPPARCOS errors for thesestars of 0.79 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(III) proper motions have atypical mean error of 0.93 mas/year, which is by a factor of about 2better than the corresponding error for the HIPPARCOS values of 1.83mas/year (cosmic errors included).
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Continuous declination system set up by observations of photoelectric astrolabe Mark I In Irkutsk. The first results of international cooperation between CSAO and VS NIIFTRI
The Photoelectric Astrolabe Mark I (PHA I) has been revised with a newcombined prism which could work as an almucantar with zenith distance of45(deg) , to measure continuous declinations at the latitude of Irkutsk,Russia (phi = 52fdg2 ). The PHA I has been working at the astronomicalbase of VS NIIFTRI in Irkutsk since Nov. 1995 based on an internationalcooperation agreement of near 4 years for star catalogue and EOPmeasurements. The first observing program was ended in June 1997, givingcorrections in both right ascension and declination to 200 stars with noblind zone in declination determination, which most astrolabe cataloguesin the world usually would have. Appendix is only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html.
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Photoelectric Photometry of Herbig Ae/be and Related Stars in the Vilnius Photometric System
A catalog of photoelectric photometry of 62 Herbig Ae/Be and relatedstars in the Vilnius system is presented. It contains stars down to V =12 mag located mainly in the northern hemisphere and observed in theperiod of 1994--1996.
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A study of the candidates for Herbig Ae/Be stars HD 35929 and HD 203024.
Not Available
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Photometric variability of the Herbig Ae/Be star HD 200775
We present results of photometric monitoring of HD 200775 in thepassbands X and V of the VILGEN system obtained over the period fromSeptember 1994 to May 1995. It is shown that the star varies with aperiod of 10.225+/- 0.041 days and an amplitude of 0.02 mag in Xpassband. The variations on the time scale of several hours and/or daysare also confirmed.
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Narrow-band photometry of the long-period variables.
Not Available
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Improved Mean Positions and Proper Motions for the 995 FK4 Sup Stars not Included in the FK5 Extension
Not Available
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On the distance of dark clouds in the vicinity of the reflection nebula NGC 7023 in Cepheus
Distance to a group of dark clouds at moderate galactic latitudes Lynds1147, 1148, 1152, 1155, 1157, 1158, 1167, 1168, 1170, 1171, 1172, 1173,and 1174 is estimated from the extinction AV vs distance plot. Thisdependence is based on photometry of 79 stars down to V = 12.5 in theVilnius photometric system and their two-dimensional classification. Thedistance of the L1147/1158 group of clouds is found to be 325 +/- 13 pcand that of the L1167/1174 or NGC 7023 group of clouds is 288 +/- 25 pc.A number of stars with peculiar energy distribution has been found.
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On the possibility of obtaining strip distributions of radio brightness by the minimal phase method
Minimal-phase strip distributions of the radio brightness have beenobtained for 15 cosmic sources at frequency 1425 MHz. It is shown thatthe minimal phase method for recovering the radio brightnessdistribution may be more effective than the principal solution methodand the fitting method.
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Interstellar extinction and polarimetric properties of the star HD 200775
Reddening and polarization are obtained and separated into intrinsic andinterstellar components for the Herbig Be star HD 200775, which issurrounded by the NGC 7023 reflection nebula. A reddening map based onstar counts is used to derive the relation between (C-13)O columndensity and extinction, and the maximum interstellar polarization isfound to be 0.88 percent at the maximum wavelength of 0.532 microns;this indicates that the size distribution of the particles in the cloudresponsible for the optical extinction and polarization is rathersimilar to that of the surrounding interstellar medium.
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Optical monitoring of Orion population stars. I - Results for some T Tauri and Herbig Ae/Be stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1982AJ.....87.1710H&db_key=AST
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B V Observations of Six Red Variable Stars
Not Available
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Spectral types for early-type stars observed by SKYLAB
MK spectral types are presented for 246 early-type stars observed withthe S-019 ultraviolet stellar astronomy experiment on Skylab. K-linetypes are also given where applicable, and various peculiar stars areidentified. The peculiar stars include five silicon stars, a shell star,a helium-rich star, a silicon-strontium star, a chromium-europium star,and two marginal metallic-line stars.
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Photoelektrische Photometrie von Shell-Sternen
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...15..311H&db_key=AST
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INHABITED SKY
