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Pulkovo compilation of radial velocities for 35495 stars in a common system.
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| New Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate
The birthrate of stars of masses >=10 Msolar is estimatedfrom a sample of just over 400 O3-B2 dwarfs within 1.5 kpc of the Sunand the result extrapolated to estimate the Galactic supernova ratecontributed by such stars. The solar-neighborhood Galactic-plane massivestar birthrate is estimated at ~176 stars kpc-3Myr-1. On the basis of a model in which the Galactic stellardensity distribution comprises a ``disk+central hole'' like that of thedust infrared emission (as proposed by Drimmel and Spergel), theGalactic supernova rate is estimated at probably not less than ~1 normore than ~2 per century and the number of O3-B2 dwarfs within the solarcircle at ~200,000.
| Pre-main sequence star Proper Motion Catalogue
We measured the proper motions of 1250 pre-main sequence (PMS) stars andof 104 PMS candidates spread over all-sky major star-forming regions.This work is the continuation of a previous effort where we obtainedproper motions for 213 PMS stars located in the major southernstar-forming regions. These stars are now included in this present workwith refined astrometry. The major upgrade presented here is theextension of proper motion measurements to other northern and southernstar-forming regions including the well-studied Orion and Taurus-Aurigaregions for objects as faint as V≤16.5. We improve the precision ofthe proper motions which benefited from the inclusion of newobservational material. In the PMS proper motion catalogue presentedhere, we provide for each star the mean position and proper motion aswell as important photometric information when available. We providealso the most common identifier. The rms of proper motions vary from 2to 5 mas/yr depending on the available sources of ancient positions anddepending also on the embedding and binarity of the source. With thiswork, we present the first all-sky catalogue of proper motions of PMSstars.
| Catalog of Galactic OB Stars
An all-sky catalog of Galactic OB stars has been created by extendingthe Case-Hamburg Galactic plane luminous-stars surveys to include 5500additional objects drawn from the literature. This work brings the totalnumber of known or reasonably suspected OB stars to over 16,000.Companion databases of UBVβ photometry and MK classifications forthese objects include nearly 30,000 and 20,000 entries, respectively.
| 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
| Statistical analysis of intrinsic polarization, IR excess and projected rotational velocity distributions of classical Be stars
We present the results of statistical analyses of a sample of 627 Bestars. The parameters of intrinsic polarization (p*),projected rotational velocity (v sin i), and near IR excesses have beeninvestigated. The values of p* have been estimated for a muchlarger and more representative sample of Be stars (~490 objects) thanpreviously. We have confirmed that most Be stars of early spectral typehave statistically larger values of polarization and IR excesses incomparison with the late spectral type stars. It is found that thedistributions of p* diverge considerably for the differentspectral subgroups. In contrast to late spectral types (B5-B9.5), thedistribution of p* for B0-B2 stars does not peak at the valuep*=0%. Statistically significant differences in the meanprojected rotational velocities (/line{vsin i}) are found for differentspectral subgroups of Be stars in the sense that late spectral typestars (V luminosity class) generally rotate faster than early types, inagreement with previously published results. This behaviour is, however,not obvious for the III-IV luminosity class stars. Nevertheless, thecalculated values of the ratio vt/vc of the truerotational velocity, vt, to the critical velocity forbreak-up, vc, is larger for late spectral type stars of allluminosity classes. Thus, late spectral type stars appear to rotatecloser to their break-up rotational velocity. The distribution of nearIR excesses for early spectral subgroups is bi-modal, the position ofthe second peak displaying a maximum value E(V-L)~ 1 . m 3for O-B1.5 stars, decreasing to E(V-L)~0. m8 for intermediatespectral types (B3-B5). It is shown that bi-modality disappears for latespectral types (B6-B9.5). No correlations were found betweenp* and near IR excesses and between E(V-L) and vsin i for thedifferent subgroups of Be stars. In contrast to near IR excesses, arelation between p* and far IR excesses at 12 mu m is clearlyseen. A clear relation between p* and vsin i (as well asbetween p* and /line{vsin i}/vc) is found by thefact that plots of these parameters are bounded by a ``triangular"distribution of p*: vsin i, with a decrease of p*towards very small and very large vsin i (and /line{vsini}/vc) values. The latter behaviour can be understood in thecontext of a larger oblateness of circumstellar disks for the stars witha rapid rotation. From the analysis of correlations between differentobservational parameters we conclude that circumstellar envelopes forthe majority of Be stars are optically thin disks with the range of thehalf-opening angle of 10degr
| Analysis of correlations between polarimetric and photometric characteristics of young stars. A new approach to the problem after eleven years' study
We present the results of the investigation of correlations between thepolarimetric and photometric characteristics of a sample (496 objects)of young Herbig Ae/Be (HAEBE) stars and T Tauri (TT) stars. It is shownthat, for 85% of the sample stars there is a general relation betweenthe degree of optical polarization and the infrared colour index(V-L)_obs and the colour excess E(V-L) due to the contribution of acircumstellar dust shell. Polarimetric data were also compared with thevalue of vsin i to search for a possible correlation between thepolarization and an inclination of circumstellar disks. Polarimetricdata as well as IR excesses are considered and compared for differentsubgroups of young stars namely: HAEBE and TT stars with Algol-likeminima of brightness (26 objects), Vega-type stars and post HAEBE stars(114 objects) and young solar-type stars (58 objects). For statisticalpurposes the data for young stars were compared with those collected fordifferent groups of evolved objects such as: classical Be stars (~300objects), Mira Ceti stars (39 objects), early-type supergiants from theSerkowski et al. (\cite{serk}) catalogue (120 objects) and main sequence(MS) stars within 50 pc from the Sun from the Leroy (\cite{leroy})catalogue (68 objects). The value of polarization is discussed incontext with the stages of evolution of circumstellar shells which wereestablished by comparison of spectral energy distribution in the far IR(using the IRAS data). It is shown that most young stars havestatistically larger value of polarization in comparison with the starswhich are on a stage of evolution close to MS. We are able to contendthat the changes in polarimetric behaviour of young stars are connectedwith evolution of their circumstellar shells. Appendices 1 to 5 are onlyavailable in electronic form at http://www.edpsciences.org
| ISO spectroscopy of young intermediate-mass stars in the BD+40deg4124 group
We present the results of ISO SWS and LWS grating scans towards thethree brightest members of the BD+40deg4124 group in theinfrared: BD+40deg4124 (B2Ve), LkHα 224 (A7e) and theembedded source LkHα 225. Emission from the pure rotational linesof H_2, from ro-vibrational transitions of CO, from PAHs, from H irecombination lines and from the infrared fine structure lines of [Feii], [Si ii], [S i], [O i], [O iii] and [C ii] was detected. Theseemission lines arise in the combination of a low-density (~102 cm-3) H ii region with a clumpy PDR in thecase of BD+40deg4124. The lower transitions of the infrared Hi lines observed in BD+40deg4124 are optically thick; mostlikely they arise in either a dense wind or a circumstellar disk. Thissame region is also responsible for the optical H i lines and the radiocontinuum emission. In the lines of sight towards LkHα 224 andLkHα 225, the observed emission lines arise in a non-dissociativeshock produced by a slow (~ 20 km s-1) outflow arising fromLkHα 225. Toward LkHα 225 we also observe a dissociativeshock, presumably located closer to the outflow source than thenon-dissociative shock. In the line of sight towards LkHα 225 weobserved absorption features due to solid water ice and amorphoussilicates, and due to gas-phase H_2O, CO and CO_2. No solid CO_2 wasdetected towards LkHα 225, making this the first line of sightwhere the bulk of the CO_2 is in the gas-phase. Based on observationswith ISO, an ESA project with instruments funded by ESA Member States(especially the PI countries: France, Germany, the Netherlands and theUnited Kingdom) and with the participation of ISAS and NASA.
| Revisiting Hipparcos data for pre-main sequence stars
We cross-correlate the Herbig & Bell and Hipparcos Catalogues inorder to extract the results for young stellar objects (YSOs). Wecompare the distances of individual young stars and the distance oftheir presumably associated molecular clouds, taking into accountpost-Hipparcos distances to the relevant associations and usingHipparcos intermediate astrometric data to derive new parallaxes of thepre-main sequence stars based on their grouping. We confirm that YSOsare located in their associated clouds, as anticipated by a large bodyof work, and discuss reasons which make the individual parallaxes ofsome YSOs doubtful. We find in particular that the distance of TaurusYSOs as a group is entirely consistent with the molecular clouddistance, although Hipparcos distances of some faint Taurus-Auriga starsmust be viewed with caution. We then improve some of the solutions forthe binary and multiple pre-main sequence stars. In particular, weconfirm three new astrometric young binaries discovered by Hipparcos:RY Tau, UX Ori, and IXOph. Based on observations made with the ESA Hipparcosastrometry satellite
| A Photometric Catalog of Herbig AE/BE Stars and Discussion of the Nature and Cause of the Variations of UX Orionis Stars
UBVR photometric monitoring of Herbig Ae/Be stars and some relatedobjects has been carried out at Maidanak Observatory in Uzbekistan since1983. More than 71,000 observations of about 230 stars have beenobtained and are made available for anonymous ftp. Virtually all HerbigAe/Be stars observed are irregular variables (called ``UXors'' after UXOri), but there is a wide range of amplitudes from barely detectable tomore than 4 mag in V. Our data confirm the results of previous studies,which indicate that large-amplitude variability is confined to starswith spectral types later than B8. The distribution of variabilityranges is quite similar to what is seen in classical T Tauri stars. Acareful search has failed to reveal any evidence for periodic variationsup to 30 days, which can be interpreted as rotation periods. This is aclear distinction between the light variations of low-mass and high-masspre-main-sequence stars. The Herbig Ae/Be stars evidently do not possesseither the large, stable cool spots or persistent hot spots associatedwith strong surface magnetic fields and magnetically funneled accretionin classical T Tauri stars. A wide variety of shapes, timescales, andamplitudes exists, but the most common behavior is well illustrated bythe light curve of LkHα 234. There are two principal components:(1) irregular variations on timescales of days around a mean brightnesslevel that changes on a much longer timescale (typically years),sometimes in a quasi-cyclic fashion, and (2) occasional episodes of deepminima, occurring at irregular intervals but more frequently near thelow points of the brightness cycles. Our data suggest that many T Tauristars of K0 and earlier spectral type share the same variabilitycharacteristics as Herbig Ae/Be stars and should be regarded as UXors.Two FU Orionis stars (``FUors''), FU Ori and V1515 Cyg, also have recentlight curves that are similar, in some respects, to UXors. The mostdeveloped model to account for the variations of some large-amplitudeUXors involves variable obscuration by circumstellar dust clumpsorbiting the star in a disk viewed nearly edge-on. However, there areproblems in extending this model to the entire class, which lead us topropose an alternative mechanism, i.e., unsteady accretion. Evidencefavoring the accretion model over the obscuration model is presented. Itis suggested that the thermal instability mechanism responsible foroutbursts in interacting binary system disks, and possibly FUors, may bethe cause of the deep minima in UXors.
| Catalogue of H-alpha emission stars in the Northern Milky Way
The ``Catalogue of Stars in the Northern Milky Way Having H-alpha inEmission" appears in Abhandlungen aus der Hamburger Sternwarte, Band XIin the year 1997. It contains 4174 stars, range {32degr <= l() II< 214degr , -10degr < b() II < +10degr } having the Hαline in emission. HBH stars and stars of further 99 lists taken from theliterature till the end of 1994 were included in the catalogue. We givethe cross-identification of stars from all lists used. The catalogue isalso available in the Centre de Données, Strasbourg ftp130.79.128.5 or http://cdsweb.u-strasbg.fr and at the HamburgObservatory via internet.
| HIPPARCOS observations of pre-main-sequence stars
We present first results of Hipparcos observations of nearby low-masspre-main-sequence (PMS) stars (TTauri and Herbig Ae/Be stars). The dataobtained by Hipparcos allow us to derive weighted mean parallaxes forthree major nearby star-forming regions (SFRs), Lupus, Chamaeleon I andTaurus-Auriga. Furthermore, results on the isolated objects AB Dor andTW Hya are presented. Finally, we discuss the evolutionary status ofHerbig Ae/Be (HAEBE) stars on the basis of Hipparcos results.
| Wind diagnostics and correlations with the near-infrared excess in Herbig Ae/Be stars
Intermediate dispersion spectroscopic observations of 37 Herbig Ae/Bestars reveal that the equivalent widths of their [OI]lambda 6300 andHα emission lines, are related to their near-infrared colours inthe same fashion as the T-Tauri stars. Such a correlation stronglysupports the idea that the winds from Herbig Ae/Be stars arise in thesame manner as those from T-Tauri stars, i.e. through accretion drivenmass-loss. We also find that the [OI]lambda 6300 line luminositycorrelates better with excess infrared luminosity than with stellarluminosities, again supporting the idea that Herbig Ae/Be winds areaccretion driven. If one includes the lower mass analogues of the HerbigAe/Be stars with forbidden line emission, i.e. the classical T-Tauristars, the correlation between mass-loss rate and infrared excess spans5 orders of magnitude in luminosity and a range of masses from0.5Msun to approximately 10Msun. Our observationstherefore extend the findings of Cohen et al. (1989) and Cabrit et al.(1990) for low mass young stars and, taken in conjunction with otherevidence (Corcoran & Ray 1997), strongly support the presence ofcircumstellar disks around intermediate mass stars with forbidden lineemission. An implication of our findings is that the same outflow modelmust be applicable to these Herbig Ae/Be stars and the classical T Tauristars. Based on observations made at the La Palma Observatory, theCaltech Submillimeter Observatory, and the European SouthernObservatory/Max Planck Institute 2.2m Telescope.
| HIPPARCOS photometry of Herbig Ae/Be stars
The photometric behaviour of a sample of 44 Herbig Ae/Be (HAeBe)candidate stars was studied using a uniform set of optical photometryobtained by the Hipparcos mission. Astrophysical parameters (distance,temperature, luminosity, mass, age) of this sample of stars were derivedas well by combining the astrometric data provided by Hipparcos withdata from literature. Our main conclusions can be summarized as follows:(1) More than 65% of all HAeBe stars show photometric variations with anamplitude larger than 0\fm05; (2) HAeBes with a spectral type earlierthan A0 only show moderate (amplitude < 0\fm5) variations, whereasthose of later spectral type can (but not necessarily have to) showvariations of more than 2\fm5. We explain this behaviour as being due tothe fact that stars with lower masses become optically visible, andhence recognizable as Herbig Ae stars, while still contracting towardsthe zero-age main sequence (ZAMS), whereas their more massivecounterparts only become optically visible after having reached theZAMS; (3) The Herbig stars with the smallest infrared excesses do notshow large photometric variations. This can be understood by identifyingthe stars with lower infrared excesses with the more evolved objects inour sample; (4) No correlation between the level of photometricvariability and the stellar v sin i could be found. If the largephotometric variations are due to variable amounts of extinction by dustclouds in the equatorial plane of the system, the evolutionary effectsprobably disturb the expected correlation between the two. Based on datafrom the Hipparcos astrometry satellite.
| 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.
| MWC 297, B1.5Ve: a zero-age main-sequence star in the Aquila Rift
Moderate-resolution optical spectra of the significantly reddened HerbigBe star MWC 297 are presented. The data are of sufficient quality thatit has been possible to obtain a spectral type for this star bycomparing heavy element absorption features with those present in earlyB field stars of known spectral type. The best fit is to B1.5V, with anuncertainty of half a sub-type. It is estimated that vsini for MWC 297is about 350 +/- 50 km s^-1, suggesting that the star's rotation axis isalmost in the plane of the sky. The reddening towards this object isreviewed and is derived afresh from spectra at wavelengths spanning theB-R optical bands. Using A_v~=8 and the absolute magnitude correspondingto B1.5V, it is argued that the distance to MWC 297 is 250 +/- 50 pcrather than ~500 pc as has recently been quoted in the literature. Atthis distance the star can be located very plausibly in the Aquila Rift. We go on to present a MERLIN 5-GHz radio map of the source which showsit to be markedly elongated in the north-south direction (to a dimensionof 125 au at 250 pc). Existing data on the optical linear polarizationof MWC 297 suggest a complicated picture that leaves open the questionof whether the radio axis might trace an ionized electron-scatteringequatorial disc. We also present and briefly discuss high-resolutionBralpha and Hei1.083-μm line profiles obtained within a week of theoptical spectra. The Hei profile is very complex, but confirms that MWC297 is an outflow source. It is noted that the Hi emission lines areundoubtedly highly variable, although the time-scales for this are notyet clear.
| Close binary systems in star-forming regions. V502 CYG in the association CYG T2.
Not Available
| Catalogue of stars in the northern Milky Way having H-alpha in emission
Not Available
| Astrometric observational results of the Hipparcos satellite and the Hubble Space Telescope.
The following aspects are reviewed: (1) the preliminary observationalresults for the Hipparcos catalogue and the Tycho catalogue obtained inthe thirty months (80% of the total Hipparcos observations); (2) theperformance test of the HST Fine Guidance Sensor, and the observationresults of the astrometric and photometric observations; (3) the recentprogress in observations and improvements of the instruments for theHipparcos satellite and the HST; (4) the authors' work in spaceastrometry.
| Hα emission from pre-main sequence stars.
We present the results of an Hα emission line observational studyof a sample of 75 pre-main sequence stars consisting of 17 HAEBE, 47 CTTand 11 WTT stars. Approximately half of the stars are faint, with abrightness in the V band >13. The spectra have been taken atresolutions =~30km/s and =~80km/s. The data shown provide information onequivalent width, radial velocity, variability and line profile.
| Hubble Space Telescope astrometric observations of pre-main sequence stars from the HIPPARCOS Program. II.
We report on high angular resolution observations with Fine GuidanceSensor (FGS) No. 3 aboard the Hubble Space Telescope of five low-masspre-main sequence stars (T Tauri stars), which have also been observedwith the Hipparcos satellite. We have observed BP Tau, RU Lup, RY Lup,AK Sco, and DI Cep and have found that none of them have companions ofcomparable brightness with a projected separation larger than the FGSresolution limit 0".01. Nebular emission from around RY Lup, RU Lup andAK Sco has been detected. Previous observations with FGS of fiveintermediate-mass pre-main sequence stars (Herbig Ae/Be stars) haveresulted in the discovery of the first sub-arc second binary of thisclass. These previous observations are also discussed here in thecontext of the physics of the objects.
| Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
| Herbig Ae/Be stars
Herbig Ae/Be stars are the higher mass counterparts of the T Tauristars. In comparison with the latter, however, relatively little isknown about them. After a historical introduction, we briefly reviewtheir optical and ultraviolet (UV) spectroscopic properties. We considerthe evidence for and against disks around Herbig Ae/Be stars; theexistence of which remains highly controversial. We also examinein-depth their interaction with the surrounding medium as manifestedthrough optical outflows. It is shown that although there aresimilarities with analogous outflows from lower mass young stars, thosefrom Herbig Ae/Be stars may be more poorly collimated. Jets, however,are found in at least some cases.
| Uvbyβ photometry of Orion population stars and related objects associated with six star forming regions
Homogeneous uvbyβ photometry of 150 stars associated with the starforming regions Taurus-Auriga, Orion, Canis Mayoris, Ophiuchus, Serpensand Cygnus, is presented here. We also present uvbyβ photometry of10 Herbig Ae/Be stars not belonging to the specific regions studiedhere. Using the (V,b-y), (β,[m1]), ([c1],[m1]) and ([u-b], T_eff_)diagrams we study the photometric properties of the sample. The effectsof duplicity, stellar rotation, and interstellar extinction on thelocation in the magnitude-color and color-color diagrams of our programstars are briefly investigated. We derive reliable photometric spectraltypes and discuss membership to the regions and to the Orion population,as well as peculiarities of the individual stars. We also find new Bstars associated with the CMa R1 star forming region and newintermediate-low mass PMS members associated with theBD+404124/BD+413731 region. The FU-Orionis stars Z CMa, V1515 Cyg andV1057 Cyg have a peculiar position in the reddening free (β,[m1])diagram. With diagrams such as (V-M _v_-5 log r+5) vs. E(b-y), E(c1) vs.E(b-y), E(m1) vs. E(b-y) and E(u-b) vs. E(b-y) we investigate the ISextinction law towards the star-forming regions. We find that the totalto selective extinction ratio to these regions is steeper than normalwith R_y_=5.4 (R_v_=4.0) and the coefficients E(c1)/E(b-y) andE(m1)/E(b-y) used to define the reddening free indices [c1] and [m1]should be numerically smaller than the generally adopted values.
| A new catalogue of members and candidate members of the Herbig Ae/Be (HAEBE) stellar group
A new up-to-date catalogue of Herbig Ae/Be (HAEBE) stars and relatedobjects is certainly needed, for both well-seasoned researchers and, inparticular, for new investigators starting to study the many interestingastrophysical properties of these very young objects. We present a briefdiscussion of the current observational characteristics that distinguishthis class from their main sequence counterparts. The HAEBE and relatedstars are listed in five tables, containing 287 objects. Table 1contains all Ae and Be stars which historically are recognized as trueHAEBE stars or potential candidate members. Table 2 gives the stars ofspectral type Fe, and emission line stars with very uncertain or unknownspectral type. In Table 3 are given all known Extreme Emission LineObjects (EELOs), of which most have not been identified to belong to anyspecific group. Table 4a and b list other Bep or B[e] stars with strongIR-excess and unknown spectral type. Table 5 contains the non-emissionline possible young objects. Furthermore, Table 6 contains 35 starsrejected from former published lists of HAEBE stars. In these tables weare including coordinates, spectral types, visual magnitudes, ranges inphotometric variability and references of several key publicationsrelated to each object. Relevant remarks, such as the presence of anebula in the vicinity of an object, are also given.
| A Study of the Kinematics of the Local Dark Clouds
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| Hubble space telescope astrometric observations of pre-main sequence stars for the HIPPARCOS program
We report on the first set of high angular resolution observations withFine Guidance Sensor (FGS) #3 aboard the Hubble Space Telescope of asample of T-Tauri and Herbig Ae/Be pre-main sequence stars, which havealso been observed with the HIPPARCOS satellite. Among the 5 Ae/Be starsobserved so far of particular interest is the new double HIPPARCOS InputCatalog (HIC) 35488 the first close visual pair in this class of starsand possibly a candidate orbital binary. Repeated FGS astrometrycombined with the parallaxes provided by HIPPARCOS could yield the firstdirect determination of the mass of an Ae/Be type pre-main sequencesystem. Finally, the timely availability of these FGS measurements willhelp the validation of the algorithms applied to the HIPPARCOS data todetect and possibly measure close pairs.
| A high-sensitivity survey of radio continuum emission from Herbig Ae/Be stars
Results of a high-sensitivity VLA/Australia Telescope survey of radiocontinuum emission from the 57 Herbig Ae/Be stars and candidates in the1984 catalog of Finkenzeller and Mundt are presented. Twelve stars weredetected at the primary observing wavelength of 3.6 cm, on the basisthat not less than 4 sigma radio sources lie within 1 arcsec of theoptical positions. It is suggested that the radio emission ispredominantly thermal and in many cases wind-related. The unusualeclipsing binary TY CrA is an exception and is classified as anonthermal radio source on the basis of its decidedly negative spectralindex (alpha = -1.2). A simple spherically symmetric free-fall accretionmodel is used to show that the predicted radio fluxes due to accretionat rates, estimated in the literature, of about 10 exp -6 to 10 exp -5solar mass/yr are one to four orders of magnitude larger than observed.
| A search for Herbig-Haro objects near Herbig Ae/Be stars
I have conducted an S II forbidden-line imaging search for Herbig-Haroobjects in the vicinity of 32 Herbig Ae/Be stars. This survey shouldprovide the basis for the study of optical outflows associated withintermediate-mass young stars. New Herbig-Haro objects were found nearHK Ori, BD+46 deg 3731, and probably BD+41 deg 3471. Possible jets werefound associated with a faint star near HK Ori, another faint star nearElias 1, and AS 310. Only the HK Ori Herbig-Haro object has beenconfirmed spectroscopically.
| Water Masers Associated with Herbig Be-Stars
Abstract image available at:http://adsabs.harvard.edu/abs/1993A&A...272..249P
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Observation and Astrometry data
| Constellation: | はくちょう座 |
| Right ascension: | 20h24m15.71s |
| Declination: | +42°18'01.4" |
| Apparent magnitude: | 9.931 |
| Proper motion RA: | -4.7 |
| Proper motion Dec: | -6.4 |
| B-T magnitude: | 9.943 |
| V-T magnitude: | 9.932 |
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INHABITED SKY
