Contingut
Imatges
Carregar la teva Imatge
DSS Images Other Images
Articles Relacionats
Apsidal motion in eccentric eclipsing binaries: CW Cephei, V478 Cygni, AG Persei, and IQ Persei
Aims.About thirty new times of minimum light recorded with photoelectricor CCD photometers were obtained for four early-type eccentric-orbiteclipsing binaries CW Cep (P=2.73d, e=0.029), V478 Cyg ( 2.88d, 0.016),AG Per ( 2.03d, 0.071), and IQ Per ( 1.74d, 0.076). Methods:.Their O-C diagrams were analysed using all reliable timings found inthe literature, and elements of apsidal motion were improved.Results: .We confirm relatively short periods of apsidal motion of about46, 27, 76, and 124 years for CW Cep, V478 Cyg, AG Per, and IQ Per,respectively. The corresponding internal structure constants, log k_2,are then found to be -2.12, -2.25, -2.15, and -2.36, under theassumption that the component stars rotate pseudosynchronously. Therelativistic effects are negligible, being up to 8% of the total apsidalmotion rate in all systems. Using the light-time effect solution, wehave predicted a faint third component orbiting with a period of about39 years for CW Cep.
| Precision Kinematics and Related Parameters of the α Persei Open Cluster
A kinematical study of the nearby open cluster α Persei ispresented based on the astrometric proper motions and positions in theTycho-2 catalog and Second USNO CCD Astrographic Catalog (UCAC2). Usingthe astrometric data and photometry from the Tycho-2 and ground-basedcatalogs, 139 probable members of the cluster are selected, 18 of themnew. By the classical convergent point method, systematic motions ofstars inside the cluster and velocity dispersions are estimated. Asdirectly observed, the upper limit on the internal velocity dispersionper coordinate is 1.1 km s-1. The actual velocity dispersionis much smaller than that value, since all of it appears to come fromthe expected errors of the astrometric proper motions. The relativeposition of the convergent point with respect to the cluster starsyields the ``astrometric'' radial velocity, which turns out larger by afew km s-1 than the mean observed spectroscopic radialvelocity. This implies an overall contraction of the cluster. Kinematicparallaxes are computed for each member, and an improved H-R diagram isconstructed. An age of 52 Myr is determined by isochrone fitting. Thestar α Per itself fits an isochrone of this age computed withovershooting from the boundary of the convective zone. The theoreticalmass of the star α Per is 6.65 Msolar. With respect tothe common center of mass, half of the higher mass members (earlier thanG) are located within a radius of 10.3 pc. The cluster appears to beroughly twice as large, or as sparse, as the Pleiades, retainingnonetheless a similar dynamical coherence. The low rate of binaries isanother feature of this cluster, where we find only about 20% of membersto be known or suspected spectroscopic, astrometric, or visual binariesor multiple systems. X-ray emitters in the cluster appear to have thesame dispersion of internal velocities as the rest of the membership.The cluster is surrounded by an extended, sparse halo of comovingdwarfs, which are found by combining the proper-motion data from UCAC2with Two Micron All-Sky Survey infrared photometry. Since many of theseexternal stars are outside the tidal radius, the cluster being in anactive stage of disintegration or evaporation could be considered. Thishypothesis is not supported by the weak compression and thenonmeasurable velocity dispersion found in the kinematic analysis. Asearch for stars ejected from the α Persei cluster is carried outby tracking a large number of nearby stars 70 Myr back in time andmatching their positions with the past location of the cluster. Only oneplausible ejection is found prior to 10 Myr ago. The nearby star GJ 82,an active M dwarf with a strong Hα emission, is likely a formermember ejected 47 Myr ago at 5 km s-1.
| Photometry and Analysis of the Eclipsing Binary IQ Persei
Photoelectric observations of the eclipsing binary IQ Persei have beencarried out in B and V colours at Ege University Observatory. Thecorresponding light curves were analyzed by synthesis techniques. Theabsolute physical parameters and apsidal motion period (122 yr) of thesystem were obtained. The results have been compared with theoreticalevolutionary models which include both mass loss and convectiveovershooting. Theoretical evolutionary tracks of the component starsindicate an age of 1.3 × 108 years and an apsidalmotion constant of 0.0040 which is greater than its observed value byonly about 5%. The A7 secondary of the eclipsing pair is still close tothe zero-age main sequence but B7 primary is about halfway through itsmain sequence life-time.
| Photometric versus empirical surface gravities of eclipsing binaries.
Systematic differences in photometric stellar surface gravitydetermination are studied by means of the comparison with empiricalvalues derived from detached double-lined eclipsing binaries.Photometric gravities were computed using Moon & Dworetsky(1985MNRAS.217..305M) grids based on Kurucz (1979ApJS...40....1K)atmosphere models, and empirical gravities were taken from Andersen(1991A&ARv...3...91A). Individual Stroemgren colours and βindices of each component of the binary system have to be taken intoaccount to correctly analyze the observed differences. A compilation ofdata on a sample containing 30 detached double-lined eclipsing binarieswith accurate (=~1-2%) determination of mass and radius and availableuvbyHbeta_ photometric data is also presented. Correction ofthe differences in terms of T_eff_ and logg for the range11000K
| Photoelectric minima of 30 eclipsing binary systems
Not Available
| Stellar spectrophotometric standards. II
Not Available
| Apsidal Motion of IQ Persei
Not Available
| Absolute dimensions and masses of eclipsing binaries. V - IQ Persei
New photometric and spectroscopic observations of the 1.7 day eclipsingbinary IQ Persei (B8 + A6) have been analyzed to yield very accuratefundamental properties of the system. Reticon spectroscopic observationsobtained at McDonald Observatory were used to determine accurate radialvelocities of both stars in this slightly eccentric large light-ratiobinary. A new set of VR light curves obtained at McDonald Observatorywere analyzed by synthesis techniques, and previously published UBVlight curves were reanalyzed to yield accurate photometric orbits.Orbital parameters derived from both sets of photometric observationsare in excellent agreement. The absolute dimensions, masses,luminosities, and apsidal motion period (140 yr) derived from theseobservations agree well with the predictions of theoretical stellarevolution models. The A6 secondary is still very close to the zero-agemain sequence. The B8 primary is about one-third of the way through itsmain-sequence evolution.
| UBV photometry of eclipsing binaries with visual companions
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971PASP...83...69H&db_key=AST
| A UBV photometric study of IQ Persei
Abstract image available at:http://adsabs.harvard.edu/abs/1970PASP...82.1077H
|
Enviar un nou article
Enllaços Relacionats
- - No s'ha trobat enllaços -
Enviar un nou enllaç
Membre dels grups següents:
|
Dades d'Observació i Astrometria
| Constel·lació: | Perseus |
| Ascensió Recta: | 04h00m20.47s |
| Declinació: | +47°34'18.0" |
| Magnitud Aparent: | 8.366 |
| Distancia: | 299.401 parsecs |
| Moviment propi RA: | 17.3 |
| Moviment propi Dec: | -25.9 |
| B-T magnitude: | 8.618 |
| V-T magnitude: | 8.387 |
Catàlegs i designacions:
|
