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Photometry of symbiotic stars. XI. EG And, Z And, BF Cyg, CH Cyg, CI Cyg, V1329 Cyg, TX CVn, AG Dra, RW Hya, AR Pav, AG Peg, AX Per, QW Sge, IV Vir and the LMXB V934 Her
We present new photometric observations of EG And, Z And, BF Cyg, CHCyg, CI Cyg, V1329 Cyg, TX CVn, AG Dra, RW Hya, AG Peg, AX Per, IV Virand the peculiar M giant V934 Her, which were made in the standardJohnson UBV(R) system. QW Sge was measured in the Kron-Cousin B, V,RC, IC system and for AR Pav we present its newvisual estimates. The current issue gathers observations of theseobjects to December 2003. The main results can be summarized as follows:EG And: The primary minimum in the U light curve (LC) occurred at theend of 2002. A 0.2 -- 0.3 mag brightening in U was detected in theautumn of 2003. Z And: At around August 2002 we detected for the firsttime a minimum, which is due to eclipse of the active object by the redgiant. Measurements from 2003.3 are close to those of a quiescent phase.BF Cyg: In February 2003 a short-term flare developed in the LC. Adifference in the depth of recent minima was detected. CH Cyg: This starwas in a quiescent phase at a rather bright state. A shallow minimumoccurred at JD 2 452 730, close to the position of the inferiorconjunction of the giant in the inner binary of the triple-star model ofCH Cyg. CI Cyg: Our observations cover the descending branch of a broadminimum. TX CVn: At/around the beginning of 2003 the star entered abright stage containing a minimum at JD 2 452 660. AG Dra: Newobservations revealed two eruptions, which peaked in October 2002 and2003 at 9.3 in U. AR Pav: Our new visual estimates showed atransient disappearance of a wave-like modulation in the star'sbrightness between the minima at epochs E = 66 and E = 68 and itsreappearance. AG Peg: Our measurements from the end of 2001 showedrather complex profile of the LC. RW Hya: Observations follow behaviourof the wave-like variability of quiet symbiotics. AX Per: In May 2003 a0.5 mag flare was detected following a rapid decrease of the light to aminimum. QW Sge: CCD observations in B, V, RC, ICbands cover a period from 1994.5 to 2003.5. An increase in the star'sbrightness by about 1 mag was observed in all passbands in 1997. Lesspronounced brightening was detected in 1999/2000. V934 Her: Ourobservations did not show any larger variation in the optical as areaction to its X-ray activity.
| The symbiotic star CH Cygni - II. The ejecta from the 1998-2000 active phase
We present Hubble Space Telescope (HST) imaging, a Very Large Array(VLA) radio map (4.74 GHz), optical high-resolution (echelle)spectroscopy and UBV photoelectric photometry of the symbiotic star CHCyg obtained during its 1998-2000 active phase. The HST imaging, takenduring eclipse, shows the central stars are embedded in a nebulaextending to 620 +/- 150 au for a distance of 270 +/- 66 pc. The innernebula is strongly influenced by the onset of activity and associatedoutflow in 1998. The surface brightness contours of the contemporaneousradio VLA observation agree well with HST images. Photometricobservations of the broad 1999 U-minimum suggest that it is due to theeclipse of the active hot component by the giant on the long-period(14.5 yr) outer orbit. We also find that the onset of the 1998 and the1992 active periods occur at the same orbital phase of the inner binary.Spectroscopic observations reveal two types of outflow from the activestar: a high-velocity (>1200 km s-1) hot star windsporadically alternating with a more massive outflow indicated byP-Cygni-like profiles. We present evidence connecting the extendednebulosity with the high-velocity shocked outflow, and hence theactivity in the central binary.
| Rotational Velocities of B Stars
We measured the projected rotational velocities of 1092 northern B starslisted in the Bright Star Catalogue (BSC) and calibrated them againstthe 1975 Slettebak et al. system. We found that the published values ofB dwarfs in the BSC average 27% higher than those standards. Only 0.3%of the stars have rotational velocities in excess of two-thirds of thebreakup velocities, and the mean velocity is only 25% of breakup,implying that impending breakup is not a significant factor in reducingrotational velocities. For the B8-B9.5 III-V stars the bimodaldistribution in V can be explained by a set of slowly rotating Ap starsand a set of rapidly rotating normal stars. For the B0-B5 III-V starsthat include very few peculiar stars, the distributions in V are notbimodal. Are the low rotational velocities of B stars due to theoccurrence of frequent low-mass companions, planets, or disks? Therotational velocities of giants originating from late B dwarfs areconsistent with their conservation of angular momentum in shells.However, we are puzzled by why the giants that originate from the earlyB dwarfs, despite having 3 times greater radii, have nearly the samerotational velocities. We find that all B-type primaries in binarieswith periods less than 2.4 days have synchronized rotational and orbitalmotions; those with periods between 2.4 and 5.0 days are rotating withina factor 2 of synchronization or are ``nearly synchronized.'' Thecorresponding period ranges for A-type stars are 4.9 and 10.5 days, ortwice as large. We found that the rotational velocities of the primariesare synchronized earlier than their orbits are circularized. The maximumorbital period for circularized B binaries is 1.5 days and for Abinaries is 2.5 days. For stars of various ages from 107.5 to1010.2 yr the maximum circularized periods are a smoothexponential function of age.
| Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i
This work is the second part of the set of measurements of v sin i forA-type stars, begun by Royer et al. (\cite{Ror_02a}). Spectra of 249 B8to F2-type stars brighter than V=7 have been collected at Observatoirede Haute-Provence (OHP). Fourier transforms of several line profiles inthe range 4200-4600 Å are used to derive v sin i from thefrequency of the first zero. Statistical analysis of the sampleindicates that measurement error mainly depends on v sin i and thisrelative error of the rotational velocity is found to be about 5% onaverage. The systematic shift with respect to standard values fromSlettebak et al. (\cite{Slk_75}), previously found in the first paper,is here confirmed. Comparisons with data from the literature agree withour findings: v sin i values from Slettebak et al. are underestimatedand the relation between both scales follows a linear law ensuremath vsin inew = 1.03 v sin iold+7.7. Finally, thesedata are combined with those from the previous paper (Royer et al.\cite{Ror_02a}), together with the catalogue of Abt & Morrell(\cite{AbtMol95}). The resulting sample includes some 2150 stars withhomogenized rotational velocities. Based on observations made atObservatoire de Haute Provence (CNRS), France. Tables \ref{results} and\ref{merging} are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/897
| Polarimetric and Photometric Observations of the Star CH Cygni
The results of photometric and polarimetric observations of the star CHCygni in the B, V, and R filters are presented. Variations of brightnessand color indices are given as functions of the time of observation. Afairly irregular character was found, both in the brightness variationsand in the variations of color indices. The polarization observationsshowed that the light of CH Cygni is intrinsically polarized.
| Features of the Energy Distribution in the Spectrum of the Symbiotic Star CH Cyg in Different Brightness States
The results of spectrophotometric observations of CH Cyg in an activephase and during emergence from it are given: the spectral energydistribution in the 3225-7500 range with 23 resolution, the absolutemonochromatic illuminances at eight selected wavelengths in the3225-8015 , and the emission fluxes in the H and H lines. The featuresof the energy distribution in the stellar spectrum and the observedforms of variability, different between the short-wavelength and redparts of the spectrum, are determined by the instability of both of thesystem's components. In the active phase, CH Cyg's emission in theobserved spectral range can be represented as the total emission from acool M6 III giant and a hot hydrogen gas with a temperature T e =10,000-15,000 K. In the low-brightness state, the star's energydistribution fully corresponds to that of a cool giant, the spectrum ofwhich varies from M6 III to M7 III. The photometric variability of thecool component in the 8015 range is 0 m .3-0 m .4. An increase in thebrightness of the cool giant preceded a bright outburst of the hotcomponent.
| 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).
| Photometry of symbiotic stars. IX. TX CVn, CH Cyg, AX Per and AR Pav
We present new photometric observations of TX CVn, CH Cyg, AX Per and ARPav. The main results can be summarized as follows: TX CVn: Thehistorical 1893-2000 photographic/B-band light curve (LC) is presentedfor the first time. From 1892 to ~1920, the star was quiet, but thenentered a series of outbursts peaking in 1920, 1945, 1952 and 1962. From~1988 till the present time, TX Cvn has gradually declined. CH Cyg: Ourobservations cover an active phase, which began in May 1998. At thebeginning of June 1999 the star's brightness in the U band rapidlydecreased due to an eclipse of the active inner binary (the symbioticpair) by a cool giant in the outer orbit. AX Per: The historical1887-2000 photographic/B-band LC is summarized here for the first time.It is characterized by long-lasting periods of quiescence with thesuperposition of a few bright stages lasting about 1.5 orbital cycles.Our photoelectric U,B,V observations revealed a drastic change in the LCprofile, which occurred after JD 2 450 000 (1995.8). A small 0.6 magflare at that time and consequently very broad wave-like variation inthe LC developed. This event was caused by the dilution of a shellaround the hot star. AR Pav: Our observations show that the recentactive phase, which began in 1985.7 is over. During the activity, AR Pavdeveloped a complex wave-like variation at the level of ~1.5 mag in thevisual band. The transition to a quiet phase was rapid -- the wave-likevariation disappeared.
| Photometric study of the eclipsing binary EG CEP
New photoelectric B and V observations of EG Cep were taken and 11 newminima times were determined. They confirm the long-term increase of theorbital period. The light-curve analysis shows that the system issemi-detached. Mass transfer from the less to the more massive componentis responsible for the observed orbital period increase. Variations inthe transferred matter projected onto the surface of the components areresponsible for the colour dependent variable shift of the minima. Thiseffect, more pronounced in the secondary minima, explains also thedisagreement of the limb-darkening coefficient of the secondarycomponent with the theoretical value.
| The Tokyo PMC catalog 90-93: Catalog of positions of 6649 stars observed in 1990 through 1993 with Tokyo photoelectric meridian circle
The sixth annual catalog of the Tokyo Photoelectric Meridian Circle(PMC) is presented for 6649 stars which were observed at least two timesin January 1990 through March 1993. The mean positions of the starsobserved are given in the catalog at the corresponding mean epochs ofobservations of individual stars. The coordinates of the catalog arebased on the FK5 system, and referred to the equinox and equator ofJ2000.0. The mean local deviations of the observed positions from theFK5 catalog positions are constructed for the basic FK5 stars to comparewith those of the Tokyo PMC Catalog 89 and preliminary Hipparcos resultsof H30.
| Photometric Peculiarities of CH Cyg during its Recent, 1997-97, Quiescent Phase
Not Available
| Multifrequency observations of the eclipsing symbiotic triple system CH CYG during the 1992-94 active phase.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996MNRAS.282..327S&db_key=AST
| Time-resolved high-resolution spectroscopy of CH Cygni: evidence for a magnetic propeller state in 1994
We present high-resolution, time- and spatially resolved spectroscopicobservations of CH Cyg carried out in the period 1994 May-August. A timeresolution of ~10 min and S/N ratios up to 300 have been achieved. Largevariations in the main peak as well as in the wings of hydrogen emissionlines have been observed to evolve on time-scales from minutes to days.Discrete emission components on the red and blue sides of the mainemission peak reach velocities in excess of 2000 km s^-1. Blue-shiftedabsorption components cluster at mean velocities -500 km s^-1 and -700km s^-1. The presence of these high-velocity, highly variable componentsis explained in terms of a magnetic propeller state of the star on itsway toward a new bright maximum. A low-density nebula at 1-arcsecdistance from CH Cyg and aligned with the direction of the 1984 radiojet is seen in [NII], and tentatively confirmed in [OIII].
| The ROSAT all-sky survey catalogue of optically bright OB-type stars.
For the detailed statistical analysis of the X-ray emission of hot starswe selected all stars of spectral type O and B listed in the Yale BrightStar Catalogue and searched for them in the ROSAT All-Sky Survey. Inthis paper we describe the selection and preparation of the data andpresent a compilation of the derived X-ray data for a complete sample ofbright OB stars.
| Photometric Observations of Eclipses in the Symbiotic Triple System CH Cygni
Not Available
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| The long-period symbiotic binary CH Cygni. IV. High velocity spectral features as the result of a propeller action.
A short description of the behaviour of the long-period (P=5700 days)peculiar symbiotic binary CH Cyg during 1992-1994 is given. PhotometricUBV observations carried out at Tartu, Torun and Olsztyn Observatoriesshow the ever increasing brightness of the star, in particular, atshorter wavelengths. The spectrum is that of an M giant superimposed bythe hot continuum and the emission lines of HI, HeI, CaII, FeII, [FeII],[SII], [Ne III] etc. The Balmer lines occasionally show additional blue-or red-shifted emission and/or absorption components with radialvelocities ranging up to "Great Attractor" 700km/s. We interpret theseresults on the basis of the magnetic rotator model which assumes amagnetic (B~10^7^Gs) rapidly rotating white dwarf as a hot component ofthe symbiotic system. According to this model, CH Cyg is now in apropeller state, with the white dwarf's rapidly rotating magnetosphereexpelling outward the accreted matter and forming a quasi-stableenvelope close to the white dwarf. The envelope probably is becomingoptically thick. The Balmer line profiles indicate that the ejection ofmatter from the magnetosphere could take place in separate clumps.
| UBV Photometry of CH Cygni in 1993: Increasing Activity.
Not Available
| Improved Mean Positions and Proper Motions for the 995 FK4 Sup Stars not Included in the FK5 Extension
Not Available
| CH Cygni in 1992-1993: High Level of Activity
Not Available
| Renewed Activity on CH Cyg
Not Available
| An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
| The Longperiod Symbiotic Binary Ch-Cygni - Part Two - the M Giant Component - Increasing Pulsation Period and Spot-Like Activity
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1992A&A...254..127M&db_key=AST
| CH Cygni: a Very Deep Minimum Accompanied by an Episode of Activity
Not Available
| Symbiotic binaries. III - Flickering variability of CH Cygni: Magnetic rotator model
Rapid (flickering) and slow (UBV light curve) variability of CH Cyg in1974-1989 is analyzed. The flickering was present during all the1977-1987 active phase, and disappeared only at the time of eclipse in1985. In summer 1989, at the time of transitory increase of activity,the flickering reappeared for a few weeks. The flickering does notdistinguish any spotlike region. Observed changes of the absoluteamplitude of the flickering and the hot component brightness can beexplained in terms of the oblique magnetic rotator model. Rapid coherentoscillations with P of about 500 sec, observed during 3 nights in 1986and 1989, are probably due to rotation of the magnetic (B of about 10MG) white dwarf.
| A long-period symbiotic binary CH Cygni. I - A hundred years' history of variability
Results are reported from a study of the visual and blue light curves ofCH Cyg for the period 1885-1988. The data and analysis results arepresented in extensive tables, graphs, and sample spectra andcharacterized in detail. It is shown that a period of inactivity from1885 to 1963 was followed by four outburst episodes of increasingmagnitude and duration, with abrupt phase-transition-like changes frominactive to high-activity periods. These features are found to beconsistent with the three-step accretion model of Mikolajewski andMikolajewska (1988), in which a magnetic-white-dwarf active component isaccreting mass from the stellar wind of an M giant companion. Thephysical mechanisms involved in the inactive, propeller, and accretorstages of this model are explored.
| 500-sec flickering's period of CH Cyg.
Not Available
| Polarization in CH Cygni in quiet and active phases.
Not Available
| CH Cyg - Still in Activity
Not Available
| UBV Observations of Symbiotic Stars in July and October 1982
Not Available
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Osservazione e dati astrometrici
| Costellazione: | Cigno |
| Ascensione retta: | 19h23m23.80s |
| Declinazione: | +50°16'17.0" |
| Magnitudine apparente: | 6.51 |
| Distanza: | 259.74 parsec |
| Moto proprio RA: | 2.5 |
| Moto proprio Dec: | 16.6 |
| B-T magnitude: | 6.404 |
| V-T magnitude: | 6.493 |
Cataloghi e designazioni:
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