Evidence of a Massive Black Hole Companion in the Massive Eclipsing Binary V Puppis
Up to now, most stellar-mass black holes have been discovered inX-ray-emitting binaries, in which the black holes are formed through acommon-envelope evolution. Here we give evidence for the presence of amassive black hole candidate as a tertiary companion in the massiveeclipsing binary V Puppis. We found that the orbital period of thisshort-period binary (P=1.45 days) shows a periodic variation while itundergoes a long-term increase. The cyclic period oscillation can beinterpreted by the light-travel time effect via the presence of a thirdbody with a mass of no less than 10.4 Msolar. However, nospectral lines of the third body were discovered, which indicates thatit is a massive black hole candidate. The black hole candidate maycorrespond to the weak X-ray source close to V Pup, discovered by theUhuru, Copernicus, and ROSAT satellites, produced by accreting materialsfrom the massive binary via a stellar wind. The circumstellar matterwith many heavy elements around this binary may have been formed by thesupernova explosion of the progenitor of the massive black hole. All ofthe observations suggest that a massive black hole is orbiting themassive close binary V Pup with a period of 5.47 yr. Meanwhile, we foundthat the central close binary is undergoing a slow mass transfer fromthe secondary to the primary star on a nuclear timescale of thesecondary component, revealing that the system has passed through arapid mass transfer stage.
|
13 New Eclipsing Binaries with Additional Variability in the ASAS Catalogue
We present 13 new ASAS eclipsing binaries that exhibit additionalperiodic variability due to pulsations, eclipses with another period orspots. All contact and semi-detached binaries from the ASAS Cataloguewere investigated.
|
Very Large Array Plus Pie Town Astrometry of 46 Radio Stars
We have used the Very Large Array, linked with the Pie Town Very LongBaseline Array antenna, to determine astrometric positions of 46 radiostars in the International Celestial Reference Frame (ICRF). Positionswere obtained in the ICRF directly through phase referencing of thestars to nearby ICRF quasars whose positions are accurate at the 0.25mas level. Radio star positions are estimated to be accurate at the 10mas level, with position errors approaching a few milliarcseconds forsome of the stars observed. Our measured positions were combined withprevious measurements taken from as early as 1978 to obtainproper-motion estimates for all 46 stars with average uncertainties of~1.7 mas yr-1. We compared our radio star positions andproper motions with the Hipparcos Catalogue data and found consistencyin the reference frames produced by each data set on the 1 σlevel, with errors of ~2.7 mas per axis for the reference frameorientation angles at our mean epoch of 2003.78. No significant spin isfound between our radio data frame and the Hipparcos Celestial ReferenceFrame, with the largest rotation rates of +0.55 and -0.41 masyr-1 around the x- and z-axes, respectively, with 1 σerrors of 0.36 mas yr-1. Thus, our results are consistentwith a nonrotating Hipparcos frame with respect to the ICRF.
|
Pulsating Components of Eclipsing Binaries in the ASAS-3 Catalog
As a result of the search among about 11000 stars from the public ASAS-3database, we report detection of pulsating components in eleveneclipsing binaries. In particular, we have found three classical Algols,MX Pav, IZ Tel, and VY Mic, with delta Sct-type primary components. Insix other eclipsing binaries, the short-period variability can also beinterpreted in terms of delta Sct-type pulsations, but in these systemsboth components are probably main-sequence stars. In HD99612, thepulsation mode shows significant amplitude decrease during the timeinterval covered by observations. In addition, we find variability inone of the components of the eclipsing and double-lined spectroscopicO-type binary ALS 1135 which we interpret as a beta Cep-type pulsation.Finally, we find Y Cir to be a good candidate for an SPB star in aneclipsing binary system.
|
FR Scuti: a Triple VV Cephei-type System of Particular Interest
We analyse ASAS, Hipparcos and other archival photometry of FR Sct toshow it is a hierarchical triple system of VV Cephei type consisting ofa M-type supergiant and close binary of OB stars.
|
Aus den IBVS.
Not Available
|
VLA Radio Positions of Stars: 1978-1995
VLA astrometric positions of the radio emission from 52 stars arereported, from observations obtained between 1978 and 1995. Thepositions of these stars have been obtained and reduced in a uniformmanner. Based on our measurements, the offset of the optical (Hipparcos)frame from the radio reference frame is in agreement with the Hipparcosextragalactic link results, within their mean errors. Comparison of theVLA measurements with the Hipparcos optical positions confirms earlierestimates of the accuracy of these positions as 30 mas. Long-termmeasurements of UX Ari have improved its proper motion.
|
Hipparcos red stars in the HpV_T2 and V I_C systems
For Hipparcos M, S, and C spectral type stars, we provide calibratedinstantaneous (epoch) Cousins V - I color indices using newly derivedHpV_T2 photometry. Three new sets of ground-based Cousins V I data havebeen obtained for more than 170 carbon and red M giants. These datasetsin combination with the published sources of V I photometry served toobtain the calibration curves linking Hipparcos/Tycho Hp-V_T2 with theCousins V - I index. In total, 321 carbon stars and 4464 M- and S-typestars have new V - I indices. The standard error of the mean V - I isabout 0.1 mag or better down to Hp~9 although it deteriorates rapidly atfainter magnitudes. These V - I indices can be used to verify thepublished Hipparcos V - I color indices. Thus, we have identified ahandful of new cases where, instead of the real target, a random fieldstar has been observed. A considerable fraction of the DMSA/C and DMSA/Vsolutions for red stars appear not to be warranted. Most likely suchspurious solutions may originate from usage of a heavily biased color inthe astrometric processing.Based on observations from the Hipparcos astrometric satellite operatedby the European Space Agency (ESA 1997).}\fnmsep\thanks{Table 7 is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/397/997
|
The comparative accuracy of photographic observations of radio stars observed at the Engelhardt Astronomical Observatory
At the Engelhardt Astronomical Observatory (EAO), we observedphotographic positions of 113 Galactic Radio Sources (GRS) in the systemPPM catalogue (Rizvanov & Dautov 1998). Analysis of their accuracyis made by comparison with the Hipparcos catalogue (Perryman et al.1997) and astrometric catalogue of radio stars in the radio window fromthe article of Walter et al. (1991). Table 2 is only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/375/670
|
Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
|
JHK photometry of symbiotic stars
We present the results of multi-epoch JHK photometry of a sample of 30known or suspected symbiotics and related objects. These are the firstresults of an ongoing programme of near-IR monitoring of symbiotic starsfrom the Mt. Abu IR Observatory of Physical Research Laboratory (PRL).
|
Early Radio Positions of Stars
Early radio positions for a sample of 100 Hipparcos stars, threeTycho-only stars, and nine radio stars with optical positions referredto the Hipparcos/ICRS frame are analyzed. The optical proper motions areused to compare the optical and radio positions. From an original sampleof 247 radio positions for the above 112 stars, a set of 220 showscoincidence between the optical and radio centers of emission closerthan 500 mas. This set is analyzed for systematic departures between theoptical and radio positions. A smaller subset of 136 early radiopositions for 72 stars show radio-minus-optical offsets smaller than 100mas and are useful for monitoring of the spin of the Hipparcos frame.
|
Silicate and hydrocarbon emission from Galactic M supergiants
Following our discovery of unidentified infrared (UIR) band emission ina number of M supergiants in h and chi Per, we have obtained 10-μmspectra of a sample of 60 galactic M supergiants. Only three newsources, V1749 Cyg, UW Aql and IRC+40 427, appear to show the UIR bands;the others show the expected silicate emission or a featurelesscontinuum. The occurrence of UIR-band emission in M supergiants istherefore much higher in the h and chi Per cluster than in the Galaxy asa whole. Possible explanations for the origin and distribution of UIRbands in oxygen-rich supergiants are discussed. We use our spectra toderive mass-loss rates ranging from 10^-8 to 10^-4 M_solar yr^-1 for thenew sample, based on the power emitted in the silicate feature. Therelationship between mass-loss rate and luminosity for M supergiants isdiscussed, and correlations are explored between their mid-infraredemission properties.
|
Classification and Identification of IRAS Sources with Low-Resolution Spectra
IRAS low-resolution spectra were extracted for 11,224 IRAS sources.These spectra were classified into astrophysical classes, based on thepresence of emission and absorption features and on the shape of thecontinuum. Counterparts of these IRAS sources in existing optical andinfrared catalogs are identified, and their optical spectral types arelisted if they are known. The correlations between thephotospheric/optical and circumstellar/infrared classification arediscussed.
|
Radio stars for linking celestial reference frames
Radio stars play a key role in establishing the link between opticalreference frames and the conventional celestial reference frame based onextragalactic radio sources. The relevant astrometric, astrophysical andradio quantities are compiled of 66 cardinal radio stars currentlysuited to frame connection and maintenance of the link. The catalogueentries are supplied with ample bibliographical codes and annotationsfor easy data retrieval. The catalogue is available electronically atthe CDS via anonymous ftp 130.79.128.5 and viahttp://cdsweb.u-strasbg.fr/Abstract.html
|
Comparison of the Carlsberg optical reference frame with the International Celestial Reference Frame.
The optical positions of 63 extragalactic nebulae measured in the framedefined by the annual series of Carlsberg Meridian Catalogues Nos 1-8are compared with their VLBI radio positions in the InternationalCelestial Reference Frame. The differences between these radio andoptical positions are interpreted as showing the global distortion ofthe Carlsberg optical frame, which is linked to that of the FK5. Northof the equator the Carlsberg optical frame is within 0.05" of the ICRF;but south of the equator it deviates by 0.07" in right ascension and0.10" in declination. The general form of the deviations follow those ofthe FK5, which are revealed in a recent comparison of FK5 with apreliminary version of the Hipparcos catalogue (H30).
|
Optical positions of radio emitting stars.
In order to contribute to the alignment of the radio and opticalreference frames, 50 stars with confirmed radio emission and publishedradio positions were observed by astrographical means. Additionally, twoconfirmed radio-stars of fainter magnitude were observed using a CCDdirect camera with a long focus, large aperture telescope. Thereductions are made relative to four catalogues: the Carlsberg MeridianCatalogue #4, the International Reference Stars Catalogue, the Positionsand Proper Motion Catalogue and the Astrographical Catalogue ofReference Stars. The best results were obtained with the CAMC catalogue.The plate error of a radio star position is 0.07" for both rightascension and declination, rising to 0.10"-0.20" for bright stars. Tenof the program stars are not in the HIPPARCOS Input Catalogue and 12 donot belong to any of the major reference catalogues used. As soon as theHIPPARCOS results become available, its reference stars already measuredin the plates will enable us to get positions for those 10 radio starsin the HIPPARCOS system.
|
ROSAT Observations of Symbiotic Binaries and Related Objects
Not Available
|
Comparison of radio and optical positions of radio stars
A comparison between radio and optical positions of radio stars ispresented. Eighty-eight optical minus radio differences from 56 starsare considered. To produce this comparison with high precision, acatalog was compiled based on the Carlsberg Meridian Catalogues Nos. 4,5, and 6, and on a catalog of 221 radio stars observed with the Bordeauxautomatic meridian circle. Most of the radio positions are from the VeryLarge Array (VLA) facilities. The overall average differences lead to atie between the radio and optical frames at the level of 30milliarcseconds. Also the relative orientation between the two frames isexamined and is found to coincide within the limit of errors. Finally,it is found that different morphological types of radio stars give riseto different levels of agreement between the radio and optical systems.
|
Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
|
A 5 GHz VLA survey of the galactic plane
We have used the Very Large Array (VLA) to survey the inner Galaxy(absolute value of b less than 0.4 deg, l = 350-40 deg) at 5 GHz to alimiting sensitivity of between 2.5 and 10 mJy. The survey has resultedin a catalog of 1272 discrete sources (including 100 sources outside theformal survey area) of which we have tentatively identifiedapproximately 450 as ultracompact H II regions and approximately 45 asplanetary nebulae. Approximately 30% of the radio sources are detectedin the Infrared Astronomy Satellite (IRAS) Point source Catalog. Theresults confirm a scale height of only 30 pc for ultracompact H IIregions. We show that source lists generated from the IRAS Point SourceCatalog alone suffer serious selection effects; the combination of theIRAS and radio surveys allows us to produce a much more complete censusof the regions of massive star formation in our Galaxy.
|
Radio emission from stars: A survey at 250 GHz
We have used the IRAM 30 m-telescope together with the Max PlanckInstitute for Radio Astronomy (MPIfR) bolometer to survey nearly 270stars of different types for 250 GHz continuum emission. We comparethese data with their low frequency (cm-range) properties. Early typestars show very often a deviation from the uniformly expanding windmodel which we tentatively attribute to temperature and/or densityfluctuations in their deeper atmospheric layers. For WR stars thisdeviation seems to depend on the effective temperature. Pre-mainsequence stars usually seem to be surrounded by a shell of warm dustmaking a substantial contribution to the 250 GHz flux density value. Wehave found especially for nearby giants and supergiants that a layer atthe transition from photosphere to chromosphere emits ample 250 GHzradiation. We show that the present data can still be explained by asimple uniformly illuminated disk model with the known stellar radius.Optically variable stars are not very strong emitters at 250 GHz. Wepreferentially detected the more exotic ones, a few Beta Lyr-type andsymbiotic stars. Comments on many individual objects are given in theappropriate sections.
|
Photometry of VV Cep stars
Not Available
|
Infrared spectra and circumstellar emission of IRAS sources with ten-micron silicate absorption
Results are presented of near-infrared photometry carried out in the J,H, K, and L bands for 33 IRAS sources with a 10-micron silicateabsorption features. The observed sources were found to be mostlycomprised of two groups of stars which showed very different spectralcharacteristics from each other between 1 and 100 microns. These starswere either evolved OH/IR stars, which generally showed IR photometricspectra similar to black-body spectra; or they were young stellarobjects showing much broader spectral energy distributions thanblack-body spectra.
|
The SVS Numbering Series Discontinued
Not Available
|
Symbiotic stars in 1988-1989
Visual observations of 28 stars are discussed. These represent the firstBAA contribution to an international campaign of long-term photometricmonitoring of symbiotic stars.
|
Photometry of symbiotic stars - an international campaign.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1991CoSka..21..303H&db_key=AST
|
An astrometric catalogue of radio stars
The first part is presented of a radio star catalog encompassing 186objects whose selection was guided by the priority criteria of theHipparchos Input Catalogue Consortium. Since these criteria are wellsuited to the need for linkage of ground-based optical systems to radioreference frames, this first selection is also considered a suitablebase for the catalog. Seventeen categories of stellar parameters arefurnished for each of the stars, including optical and radio positions,optical and radio parallax, radial velocity, type of variability, andoptical structure.
|
Comparison of optical and radio positions of stars
Optical positions of 23 radio stars obtained recently with the automatedmeridian circle at Bordeaux in France and the Carlsberg AutomaticMeridian Circle on La Palma are compared with their radio positions. Anoffset between the radio and optical positions of 0.5 arcsec in rightascension is found for 54 Cam. No other significant offset is found. Theoptical and radio reference frames defined by the remaining 22 starsagree to within the accuracy of measurement.
|
Mass-losing M supergiants in the solar neighborhood
A list of the 21 mass-losing red supergiants (20 M type, one G type; Lgreater than 100,000 solar luminosities) within 2.5 kpc of the sun iscompiled. These supergiants are highly evolved descendants ofmain-sequence stars with initial masses larger than 20 solar masses. Thesurface density is between about 1 and 2/sq kpc. As found previously,these stars are much less concentrated toward the Galactic center thanW-R stars, which are also highly evolved massive stars. Although withconsiderable uncertainty, it is estimated that the mass return by the Msupergiants is somewhere between 0.00001 and 0.00003 solar mass/sq kpcyr. In the hemisphere facing the Galactic center there is much less massloss from M supergiants than from W-R stars, but, in the anticenterdirection, the M supergiants return more mass than do the W-R stars. Theduration of the M supergiant phase appears to be between 200,000 and400,000 yr. During this phase, a star of initially at least 20 solarmasses returns perhaps 3-10 solar masses into the interstellar medium.
|
