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A catalogue of chromospherically active binary stars (third edition)
The catalogue of chromospherically active binaries (CABs) has beenrevised and updated. With 203 new identifications, the number of CABstars is increased to 409. The catalogue is available in electronicformat where each system has a number of lines (suborders) with a uniqueorder number. The columns contain data of limited numbers of selectedcross references, comments to explain peculiarities and the position ofthe binarity in case it belongs to a multiple system, classicalidentifications (RS Canum Venaticorum, BY Draconis), brightness andcolours, photometric and spectroscopic data, a description of emissionfeatures (CaII H and K, Hα, ultraviolet, infrared),X-ray luminosity, radio flux, physical quantities and orbitalinformation, where each basic entry is referenced so users can go to theoriginal sources.
| Dynamical evolution of active detached binaries on the logJo-logM diagram and contact binary formation
Orbital angular momentum (OAM, Jo), systemic mass (M) andorbital period (P) distributions of chromospherically active binaries(CAB) and W Ursae Majoris (W UMa) systems were investigated. Thediagrams of and logJo-logM were formed from 119 CAB and 102 WUMa stars. The logJo-logM diagram is found to be mostmeaningful in demonstrating dynamical evolution of binary star orbits. Aslightly curved borderline (contact border) separating the detached andthe contact systems was discovered on the logJo-logM diagram.Since the orbital size (a) and period (P) of binaries are determined bytheir current Jo, M and mass ratio, q, the rates of OAM loss(dlogJo/dt) and mass loss (dlogM/dt) are primary parametersto determine the direction and the speed of the dynamical evolution. Adetached system becomes a contact system if its own dynamical evolutionenables it to pass the contact border on the logJo-logMdiagram. The evolution of q for a mass-losing detached system is unknownunless the mass-loss rate for each component is known. Assuming q isconstant in the first approximation and using the mean decreasing ratesof Jo and M from the kinematical ages of CAB stars, it hasbeen predicted that 11, 23 and 39 per cent of current CAB stars wouldtransform to W UMa systems if their nuclear evolution permits them tolive 2, 4 and 6 Gyr, respectively.
| Search for associations containing young stars (SACY). I. Sample and searching method
We report results from a high-resolution optical spectroscopic surveyaimed to search for nearby young associations and young stars amongoptical counterparts of ROSAT All-Sky Survey X-ray sources in theSouthern Hemisphere. We selected 1953 late-type (B-V~≥~0.6),potentially young, optical counterparts out of a total of 9574 1RXSsources for follow-up observations. At least one high-resolutionspectrum was obtained for each of 1511 targets. This paper is the firstin a series presenting the results of the SACY survey. Here we describeour sample and our observations. We describe a convergence method in the(UVW) velocity space to find associations. As an example, we discuss thevalidity of this method in the framework of the β Pic Association.
| Mass loss and orbital period decrease in detached chromospherically active binaries
The secular evolution of the orbital angular momentum (OAM), thesystemic mass (M=M1+M2) and the orbital period of114 chromospherically active binaries (CABs) were investigated afterdetermining the kinematical ages of the subsamples which were setaccording to OAM bins. OAMs, systemic masses and orbital periods wereshown to be decreasing by the kinematical ages. The first-orderdecreasing rates of OAM, systemic mass and orbital period have beendetermined as per systemic OAM, per systemic mass and per orbitalperiod, respectively, from the kinematical ages. The ratio of d logJ/dlogM= 2.68, which were derived from the kinematics of the presentsample, implies that there must be a mechanism which amplifies theangular momentum loss (AML) times in comparison to isotropic AML ofhypothetical isotropic wind from the components. It has been shown thatsimple isotropic mass loss from the surface of a component or bothcomponents would increase the orbital period.
| A catalogue of eclipsing variables
A new catalogue of 6330 eclipsing variable stars is presented. Thecatalogue was developed from the General Catalogue of Variable Stars(GCVS) and its textual remarks by including recently publishedinformation about classification of 843 systems and making correspondingcorrections of GCVS data. The catalogue1 represents thelargest list of eclipsing binaries classified from observations.
| Optical Photometry and Spectroscopy of the Suspected ``Cool Algol'' AV Delphini: Determination of the Physical Properties
We present new spectroscopic and BVRI photometric observations of thedouble-lined eclipsing binary AV Del (period=3.85 days) conducted oversix observing seasons. A detailed radial velocity and light-curveanalysis of the optical data shows the system to be most likelysemidetached, with the less massive and cooler star filling its Rochelobe. The system is probably a member of the rare class of ``coolAlgol'' systems, which are distinguished from the ``classical'' Algolsystems in that the mass-gaining component is also a late-type starrather than a B- or A-type star. By combining the spectroscopic andphotometric analyses, we derive accurate absolute masses for thecomponents of M1=1.453+/-0.028Msolar andM2=0.705+/-0.014Msolar and radii ofR1=2.632+/-0.030Rsolar andR2=4.233+/-0.060Rsolar, as well as effectivetemperatures of 6000+/-200 and 4275+/-150 K for the primary andsecondary, respectively. There are no obvious signs of activity(spottedness) in the optical light curve of the binary.
| The Eclipsing Binary System AR Monocerotis
New differential UBV photoelectric photometry and echelle spectroscopyfor the eclipsing binary AR Mon are presented. A total of 46 radialvelocities for each component are obtained using the TODCOR procedure.We solve the new and previously published multicolor light curvessimultaneously with the new radial velocities using the latest versionof the Wilson-Devinney program. We confirm that AR Mon is a semidetachedbinary consisting of two evolved giant stars and is a member of the rareclass of ``cool Algols.'' The size of the primary, more massivecomponent is about 1/3 that of its limiting lobe, and the secondary staris a lobe filler. We present two solutions, one without third light, theother including amounts of third light of 8% in V, 6% in B, and 5% in U.We determine magnitudes and colors for AR Mon's two components, as wellas for the third star. If real, the latter is estimated to be a dwarfforeground star. The mass and radius of the primary(2.480+/-0.014Msolar, 8.002+/-0.089Rsolar) placethe star very close to the evolutionary track of a 2.5Msolarsingle star of solar chemical composition, indicating that the star mayhave adjusted its structure to mass gained from its companion.Synchronous rotation rates for both stars are in excellent agreementwith vsini values determined from line profiles.
| Up-to-Date Linear Elements of Eclipsing Binaries
About 1800 O-C diagrams of eclipsing binaries were analyzed and up-todate linear elements were computed. The regularly updated ephemerides(as a continuation of SAC) are available only in electronic form at theInternet address: http://www.as.ap.krakow.pl/ephem/.
| Kinematics of chromospherically active binaries and evidence of an orbital period decrease in binary evolution
The kinematics of 237 chromospherically active binaries (CABs) werestudied. The sample is heterogeneous with different orbits andphysically different components from F to M spectral-type main-sequencestars to G and K giants and supergiants. The computed U, V, W spacevelocities indicate that the sample is also heterogeneous in velocityspace. That is, both kinematically younger and older systems exist amongthe non-evolved main sequence and the evolved binaries containing giantsand subgiants. The kinematically young (0.95 Gyr) subsample (N= 95),which is formed according to the kinematical criteria of moving groups,was compared with the rest (N= 142) of the sample (3.86 Gyr) toinvestigate any observational clues of binary evolution. Comparing theorbital period histograms between the younger and older subsamples,evidence was found supporting the finding of Demircan that the CABs losemass (and angular momentum) and evolve towards shorter orbital periods.The evidence of mass loss is noticeable on the histograms of the totalmass (Mh+Mc), which is compared between theyounger (only N= 53 systems available) and older subsamples (only N= 66systems available). The orbital period decrease during binary evolutionis found to be clearly indicated by the kinematical ages of 6.69, 5.19and 3.02 Gyr which were found in the subsamples according to the periodranges of logP<= 0.8, 0.8 < logP<= 1.7 and 1.7 < logP<=3, respectively, among the binaries in the older subsample.
| Optical Photometry and X-Ray Monitoring of the ``Cool Algol'' BD +05°706: Determination of the Physical Properties
We present new photometric observations in the BVRI bands of thedouble-lined eclipsing binary BD +05°706 conducted over threeobserving seasons, as well as new X-ray observations obtained with ROSATcovering a full orbital cycle (P=18.9 days). A detailed light-curveanalysis of the optical data shows the system to be semidetached,confirming indications from an earlier analysis by Torres et al.(published in 1998), with the less massive and cooler star filling itsRoche lobe. The system is a member of the rare class of cool Algolsystems, which are different from the ``classical'' Algol systems inthat the mass-gaining component is also a late-type star rather than aB- or A-type star. By combining the new photometry with a reanalysis ofthe spectroscopic observations reported by Torres et al., we deriveaccurate absolute masses for the components ofM1=2.633+/-0.028 Msolar andM2=0.5412+/-0.0093 Msolar, radii ofR1=7.55+/-0.20 Rsolar andR2=11.02+/-0.21 Rsolar, as well as effectivetemperatures of 5000+/-100 and 4640+/-150 K, for the primary andsecondary, respectively. There are obvious signs of activity(spottedness) in the optical light curve of the binary. Our X-ray lightcurve clearly shows the primary eclipse but not the secondary eclipse,suggesting that the primary star is the dominant source of the activityin the system. The depth and duration of the eclipse allow us to infersome of the properties of the X-ray-emitting region around that star.
| 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
| The ROSAT Bright Survey: II. Catalogue of all high-galactic latitude RASS sources with PSPC countrate CR > 0.2 s-1
We present a summary of an identification program of the more than 2000X-ray sources detected during the ROSAT All-Sky Survey (Voges et al.1999) at high galactic latitude, |b| > 30degr , with countrate above0.2 s-1. This program, termed the ROSAT Bright Survey RBS, isto more than 99.5% complete. A sub-sample of 931 sources with countrateabove 0.2 s-1 in the hard spectral band between 0.5 and 2.0keV is to 100% identified. The total survey area comprises 20391deg2 at a flux limit of 2.4 x 10-12 ergcm-2 s-1 in the 0.5 - 2.0 keV band. About 1500sources of the complete sample could be identified by correlating theRBS with SIMBAD and the NED. The remaining ~ 500 sources were identifiedby low-resolution optical spectroscopy and CCD imaging utilizingtelescopes at La Silla, Calar Alto, Zelenchukskaya and Mauna Kea. Apartfrom completely untouched sources, catalogued clusters and galaxieswithout published redshift as well as catalogued galaxies with unusualhigh X-ray luminosity were included in the spectroscopic identificationprogram. Details of the observations with an on-line presentation of thefinding charts and the optical spectra will be published separately.Here we summarize our identifications in a table which contains opticaland X-ray information for each source. As a result we present the mostmassive complete sample of X-ray selected AGNs with a total of 669members and a well populated X-ray selected sample of 302 clusters ofgalaxies with redshifts up to 0.70. Three fields studied by us remainwithout optical counterpart (RBS0378, RBS1223, RBS1556). While the firstis a possible X-ray transient, the two latter are isolated neutron starcandidates (Motch et al. 1999, Schwope et al. 1999).
| On X-Ray Variability in Active Binary Stars
We have compared the X-ray emissions of active binary stars observed atvarious epochs by the Einstein and ROSAT satellites in order toinvestigate the nature of their X-ray variability. The primary aim ofthis work is to determine whether or not active binaries exhibitlong-term variations in X-ray emission, perhaps analogous to theobserved cyclic behavior of solar magnetic activity. We find that, whilethe mean level of emission of the sample remains steady, comparison ofdifferent ROSAT observations of the same stars shows significantvariation on timescales <~2 yr, with an ``effective variability''ΔI/I=0.32+/-0.04, where I and ΔI represent the mean emissionand variation from the mean emission, respectively. A comparison of theROSAT All-Sky Survey and later pointed observations with earlierobservations of the same stars carried out with Einstein yields onlymarginal evidence for a larger variation (ΔI/I=0.38+/-0.04 forEinstein vs. ROSAT All-Sky Survey and 0.46+/-0.05 for Einstein vs. ROSATpointed) at these longer timescales (~10 yr), thus indicating thepossible presence of a long-term component to the variability. Whetheror not this long-term component is due to the presence of cyclicvariability cannot be decided on the basis of existing data. However,assuming that this component is analogous to the observed cyclicvariability of the Sun, we find that the relative magnitude of thecyclic component in the ROSAT passband can, at most, be a factor of 4,i.e., I_cyc/I_min<4. This is to be compared with the correspondingbut significantly higher solar value of ~10-10^2 derived from GOES,Yohkoh, and Solrad data. These results are consistent with thesuggestions of earlier studies that a turbulent or distributive dynamomight be responsible for the observed magnetic activity on the mostactive, rapidly rotating stars.
| Radio star catalogue observed in San Juan (RSSJ95)
Using the data observed in San Juan with the photoelectric AstrolabeMark II of the Beijing Astronomical Observatory from February, 1992 toMarch, 1997, the radio star catalogue in San Juan(RSSJ95) has beencompiled. There are 69 radio stars in this catalogue. The positions ofthe radio stars are for the epoch of observation and the equinox J2000.0and a system close to that of the system FK5. The mean precisions are+/-2.2 ms and +/-0.035'' in right ascensions and declinations,respectively. The magnitudes of stars are from 0.9 to 10.7. Thedeclinations are from -2fdg 5 to -60(deg) . The mean epoch is 1995.1.Finally, the comparison results between the Hipparcos catalogue andRSSJ95 are given.
| Magnetic activity and evolution of Algol-type stars - II
We examine the possibility of probing dynamo action in mass-losingstars, components of Algol-type binaries. Our analysis is based on thecalculation of non-conservative evolution of these systems. We model thesystems USge and betaPer where the more massive companion fills itsRoche lobe at the main sequence (case AB) and where it has a smallhelium core (early case B) respectively. We show that to maintainevolution of these systems at the late stages which are presumablydriven by stellar `magnetic braking', an efficient mechanism forproducing large-scale surface magnetic fields in the donor star isneeded. We discuss the relevance of dynamo operation in the donor starto the accelerated mass transfer during the late stages of evolution ofAlgol-type binaries. We suggest that the observed X-ray activity inAlgol-type systems may be a good indicator of their evolutionary statusand internal structure of the mass-losing stellar components.
| BD +05 706: A New Member of the Class of ``Cool Algols''
We report the serendipitous discovery of an Algol-type binary with anorbital period of 18.9 days, in which both components are cool giants(G8 III and K1-K2 III). Few systems with these characteristics are knownand are referred to as ``cool Algols,'' as opposed to the ``classicalAlgols'' in which the mass-gaining component resembles an early-typemain-sequence star. The nature of this object, which is a strong X-raysource, was discovered in the course of a spectroscopic search for TTauri stars among ROSAT All-Sky Survey sources. We derive a double-linedspectroscopic orbit leading to minimum masses of M_A = 2.481 +/- 0.023M_ȯ and M_B = 0.515 +/- 0.011 M_ȯ and a corresponding mass ratioof q ~ 0.21. We measure also projected rotational velocities of 22 and31 km s^-1, respectively, and a luminosity ratio of l_B/l_A = 1.06 +/-0.04 at ~5200 Å. The system is probably semidetached, with theaxial spin of the components synchronized with the orbital motion, andthe probability of eclipses is high. The general properties of BD +05deg706, most likely a result of case B mass exchange, are very similarto those of the other known members of this class. We discuss thecorrelation between the mass of the hotter, detached components andtheir effective temperature for all cool Algols, noted previously by D.M. Popper, as well as a trend with the orbital period. Chromosphericactivity indicators in BD +05 deg706 are compared with those of othermembers of its class, as well as with those of the classical Algols andthe RS CVn binaries. Some of the observations reported here wereobtained with the Multiple Mirror Telescope, a joint facility of theSmithsonian Institution and the University of Arizona. Based onobservations obtained during program 57.E-0646 with the 1.5 m telescopeof the European Southern Observatory on La Silla, Chile. Based onobservations obtained with the 1.23 m and 2.2 m telescopes of theGerman-Spanish Calar Alto Observatory, Spain.
| San Juan radio star catalogue and comparison with HIPPARCOS catalogue.
Not Available
| Accurate Positions for Radio Stars as Determined from CCD Observations in the Extragalactic Reference Frame.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.1679S&db_key=AST
| EUV Emission from RS Canum Venaticorum binaries.
We performed a study of 104 RS CVn systems in the extreme ultraviolet(EUV) using the all-sky survey data obtained by the Extreme UltravioletExplorer (EUVE). The present sample includes several new RS CVndetections; 11 more than in the published EUVE catalogs, and 8 more thanin the ROSAT Wide Field Camera catalog. The ratio of detections tonon-detections remained constant throughout the sky, implying that ourdetections are not limited by the exposure time but are most likelylimited by absorption from the interstellar medium. A general trend ofincreasing Lex/B (50-180Å) flux with decreasing rotational periodis clear. The dwarf systems exhibit a leveling-off for the fasterrotators. In contrast, the evolved systems exhibit no such effect. Forthe RS CVn systems the losses in the EUV represent a smaller fraction ofthe coronal radiative losses, as compared to active late-type dwarfs.
| RS CVn Versus Algol-Type Binaries: A Comparative Study of Their X-Ray Emission
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....111.2415S&db_key=AST
| The emission of the RS CVn binaries in the IRAS passbands.
In the literature, there is an ambiguity pertaining to the existence ofa far-IR excess in RS CVn systems. In the current paper we undertook astudy of the behaviour of 103 such systems in the IRAS passbands. Wefound 72 acceptable detections in the 12μm band, and 40 in the25μm band (50% more than the IRAS Point Source Catalog). Although ourfindings may be interpreted as indicating towards the existence of anexcess beyond 12μm for some systems, the evidence is not conclusivein all but two cases. These are systems GX Lib and HR 7428, with Capellabeing the only system where the IRAS fluxes in all four bands originatefrom the stellar photosphere. Given the accuracy of the data we did notfind 12μm excess for any system. We argue that the IRAS data alonecannot settle the issue, as their uncertainty is, in many cases, higherthan what the Signal-to-Noise ratio of each observation implies.Furthermore, at the higher wavelength bands the IRAS angular resolutiondrops from 0.5' at 12μm to 2' at 100μm and the background becomesvery complex, so one cannot be certain about the origin of the observedflux. The existence of IR excess in the RS CVn stars is important as faras the evolutionary scenarios for these systems are concerned. Futuremissions such as the Infrared Space Observatory will return moresensitive and accurate measurements and the ambiguity can be removed.The fluxes we quote will be helpful when planning these futureobservations, as we provide more accurate photometry and for a largerselection of sources than the IRAS Point Source Catalog.
| On the Role of Mass Transfer in X-Ray Emission of RS CVN Systems
Abstract image available at:http://adsabs.harvard.edu/abs/1995AJ....109.2187W
| Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
| Eclipse observations of RS CVn binaries. 2: A parametric model of extended matter
We have surveyed ten RS CVn binary systems and have detected largeregions of extended, prominencelike material which we have shown to be acommon feature in these systems. These extended regions are apparent asanomalous absorption features in the spectra when they obscure the diskof the eclipsed star and as weak emission features when they appear withno disk behind. We have constructed a first-generation model to verifythe general prominencelike nature of the material and to estimate itsextent and its most basic physical characteristics. In this paper wepresent our results of our modeling on four of the systems in our surveythat showed clear signatures of extended material: AW Her, MM Her, SSBoo, and UV Psc. We find that these stellar prominencelike structuresare very much larger than their solar counterparts, though their grossphysical characteristics (i.e., their electron density and temperatureand their general appearance as tenuous, vertically oriented,magnetically confined structures) are similar to those seen in solarprominences. These features appear to evolve fairly rapidly, sincemoderate- to high-velocity flows ranging from several tens of km/s to170 km/s are apparent. However, in at least one case (SS Boo) they arerecurrent over a time scale of at least a year. We conclude bydiscussing the implications of this work regarding the nature of closebinary star active structures and their evolution.
| The active dynamo stars: RS CVn, BY Dra, FK Com, Algol, W UMa, and T Tau
Not Available
| A catalog of chromospherically active binary stars (second edition)
The catalog contains 206 spectroscopic binary systems with at least onelate-type component that shows Ca II H and K emission in its spectrum.These systems include the classical RS CVn binaries and BY Dra binaries.The catalog summarizes information on the photometric, spectroscopic,orbital, and physical properties of the systems as well as space motionsand positions. Up to 42 'parameters' for each stellar system are listedfollowed by the appropriate reference to direct interested colleagues tothe original papers. A comprehensive selection of further informationfor each star is given in the individual notes. In addition, the catalogcontains a candidate list of 138 stars that have similar characteristicsbut are not definitely known binaries or have not had Ca II H and Kemission observed.
| Catalogue of astrophysical parameters of binary systems
Not Available
| Eclipse observations of RS CVn binaries. I - A survey for extended matter
We survey a number of RS CVn systems to determine the frequency andnature of circumstellar matter in these chromospherically activebinaries. A growing body of data suggests that large extended regions ofcool, prominence-like matter may be a common phenomenon in thesesystems. Our targets are eclipsing systems as the established geometriesand occultations are useful probes for such extended material. In thispaper we discuss our methods and present the results of our survey andour spectroscopic phase monitoring of these systems. We find extendedmaterial in eight of the ten systems on our present survey.
| A uvby-beta survey of northern-hemisphere active binaries. II - The m1 deficiency
New photometric observations, using the uvby and H-beta systems of 72northern-hemisphere active binaries are discussed in order to explainthe main characteristics of their spectral light intensity distribution.Values of the parameter delta(m1) range from 0.0 to 0.3 mag, whichcannot be explained in terms of metal underabundance alone. Theexistence of some mechanism responsible for such a color-index anomalyis thus suggested and is found to be in close relation with the involveddegree of solar-type activity.
| Orbits of close binaries with CA II H and K in emission. IV - Three systems with mass ratios far from unity
The properties of three semidetached systems with mass ratios differinggreatly from unity, AD Cap, RT Lac, and RV Lib, are discussed. Ca II Hand K emission is present in both components of each system, theemission appearing stronger in the hotter, detached components. Allthree system show irregularities and changes in their light curves,although photometric material is available in appreciable quantity onlyfor RT Lac. The spectral types of the detached, hotter, more massivecomponents of RT Lac and RV Lib are much later than the types ofmain-sequence stars of the same mass. However, the masses, mass ratios,and orbital angular momenta if these systems lie within the same rangesas in 'classical' Algol systems, for which the spectral types of thedetached components are generally similar to those of the stars indetached binaries with the same masses. Possible explanations for thisdichotomy are examined.
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| קבוצת-כוכבים: | גדי |
| התרוממות ימנית: | 21h39m48.92s |
| סירוב: | -16°00'21.0" |
| גודל גלוי: | 9.792 |
| תנועה נכונה: | 44.3 |
| תנועה נכונה: | 0.7 |
| B-T magnitude: | 10.935 |
| V-T magnitude: | 9.887 |
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