Near-Contact Binaries with Mass Transfer: V473 Cassiopeiae and II Persei
Photometric solutions of two short period close binaries, V473 Cas andII Per, are derived with the 2003 version Wilson-Van Hamme code. It isshown that V473 Cas is a semidetached system with the primary componentor the secondary component at its critical Roche Lobe, while II Per is amarginal contact binary system with both components filling theircritical Roche Lobes, but with a large temperature difference betweenthe two components. Both systems belong to near-contact binaries withthe light curves enhanced around the left shoulder of secondary minimum,which can be explained by hot spots on the secondary components due tothe mass transfer via a stream hitting the facing surface of thesecondary components. The orbital period investigations based on allavailable times of light minimum show a secular period existing in thesetwo targets decreasing at the rate of dP/dt = –7.61 ×10–8 days yr–1 for V473 Casand dP/dt = –7.54 ×10–8 days yr–1 for II Per.The decrease of the orbital period can be the result of mass transferfrom the primary component to the secondary one, which is consistentwith the asymmetric light curves of V473 Cas and II Per. Therefore, V473Cas and II Per are other examples displaying evidence of mass transferbetween the two components. We have collected NCBs with secular periodvariation and find that almost all SD1-type NCBs show decreasing periodsand enhancing luminosity on the left shoulder of secondary minimum intheir light curves. So the semidetached configuration with the lobefilling primary is more plausible for V473 Cas. Furthermore, thedetected enhancing amplitude of luminosity for SD2-type NCBs is smallerthan other types of NCBs, which implies that the mass transfer from theprimary component to the secondary one is stronger than the transfer inopposite direction. With the orbital period decrease, V473 Cas and IIPer will evolve into overcontact binaries with true thermal contact.
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The Near-Contact Binary RU Ursae Minoris
The near-contact binary RU UMi with an F0-type primary and a K-typesecondary was observed in 2003. With the latest version of theWilson-Devinney code, the photometric elements were computed. Theresults reveal that RU UMi is a semi-detached system with the secondarycomponent filling its Roche lobe, which should lead to an increase ofthe period for conservative mass transfer between the two components.However, an orbital period analysis shows that the orbital period ofthis system undergoes a continuous decrease at a rate ofdP/dt=-1.72×10-8d yr-1. Therefore, thecontinuous period decrease may demonstrate that the system isnonconservative. This can result from a combined effect of mass transferfrom the secondary component to the primary one and mass and angularmomentum loss from the system. With the secular mass and angularmomentum losses, RU UMi may evolve from the present short-periodnear-contact system into an A-type contact binary.
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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.
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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/.
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Catalogue of Algol type binary stars
A catalogue of (411) Algol-type (semi-detached) binary stars ispresented in the form of five separate tables of information. Thecatalogue has developed from an earlier version by including more recentinformation and an improved layout. A sixth table lists (1872) candidateAlgols, about which fewer details are known at present. Some issuesrelating to the classification and interpretation of Algol-like binariesare also discussed.Catalogue is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/417/263
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Short-period near-contact binary systems at the beginning of the overcontact phase
A detailed analysis of orbital period changes of seven near-contactbinary stars (NCBs) (BL And, V473 Cas, XZ CMi, BV Eri, RU Eri, UU Lynand GR Tau) with period less than 1 d has been performed and theirrespective O-C diagrams are formed and discussed. It is found that allsystems analysed show secular period decreasing. For V473 Cas, theanalysis of the period change was performed based on data collected byMoschner, Frank & Bastian. For XZ CMi, its period shows some complexchanges, a possible cyclic oscillation is discovered to superpose on thesecular decrease that can be explained either by the presence of a thirdbody or by magnetic activity cycles of the components. Since thethird-body assumption is consistent with the photometric solution ofRafert, XZ CMi may be a truly triple system. For BV Eri, the perioddecrease is only supported by weak evidence. All the seven systems areshort-period NCBs with AF-type primary components where both componentsare filling or nearly filling the critical Roche lobe. As the perioddecreases, the separation between both components will be reducing andthus these systems will evolve into A-type overcontact binaries. Theperiod decrease may be caused by mass transfer or/and by angularmomentum loss via magnetic braking. Combined with the published data onthe other systems of the same type, a possible statistical connectionbetween orbital period P and its rate of decrease dP/dt is obtained:dP/dt=-5.3 × 10-7×P+ 1.3 × 10-7d yr-1. This correlation indicates that the smaller theorbital period P is, the smaller its rate of change dP/dt will be. Thecorrelation found in this paper indicates that there may be a smoothtransition from A- and F-type NCBs with period decreases to the A- andF-type overcontact binaries that have period increases, and in thatsense one may postulate that the NCBs may be the progenitors of theA-type W UMa systems and will be oscillating around a marginal-contactstate as predicted by thermal relaxation oscillation (TRO) theory.
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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.
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Differential Corrections Analysis of the UBVRI Observations of AG Phoenicis
The first photoelectric analysis of the Algol-like system AG Phe basedon U, B, V, R and I light curves and modeled using the Wilson andDevinney approach, is presented. The light curves are defined by 9246individual observations. The components and the orbit appears to bestable. The primary, more massive, more luminous and greater component,eclipsed (total transit) at primary minimum, is detached from its Rochelobe (79%). The secondary nearly fills its Roche lobe (99%) and has atemperature difference of Delta T=-3310 K. Preliminary derived absolutedimensions M_1/Modot=1.42, R_1/Rodot=1.66,L_1/Lodot=7.83, log g_1=4.15 assign normal MS characteristicsand a low degree of evolution to the A8V primary, whileM_2/Mȯ=0.22, R_2/Rodot=0.93, L_2/Lodot=0.29,log g_2=3.84 suggest an evolved K2 sub-giant secondary.
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Accurate Positions Of Variable Stars Near The South Galactic Pole
Not Available
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The Period of AG Phoenicis has Decreased
Not Available
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Times of Minima of Southern Eclipsing Binaries
Not Available
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Early type high-velocity stars in the solar neighborhood. IV - Four-color and H-beta photometry
Results are presented from photometric obaservations in the Stromgrenuvby four-color and H-beta systems of early-type high-velocity stars inthe solar neighborhood. Several types of photometrically peculiar starsare selected on the basis of their Stromgren indices and areprovisionally identified as peculiar A stars, field horizontal-branchstars, metal-poor stars near the Population II and old-disk turnoffs,metal-poor blue stragglers, or metallic-line A stars. Numerousphotometrically normal stars were also found.
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I.A.U. Archives of Unpublished Observations of Variable Stars - 1981-1984 Data
Not Available
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Early-type high-velocity stars in the solar neighborhood. III - Radial velocities, rotation indices, and line-strength indices for southern candidates
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983AJ.....88.1349S&db_key=AST
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A photometric orbit for the eclipsing binary AG Phoenicis
In each of the UBV bandpasses about 1760 observations define for thefirst time the photoelectric light variation of the binary system AGPhe. A consistent set of elements is derived in the framework of theclassical model. The system would be a well-detached binary consistingof two normal A9 and K0 main-sequence components.
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IAU Archives of Unpublished Observations of Variable Stars
Not Available
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Information on the Photoelectric Observations of Variable Stars Deposited at Odessa Astronomical Observatory
Not Available
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Early-type high-velocity stars in the solar neighborhood. I - List of candidates
Suspected nearby high-velocity stars of spectral types B and A areidentified by their proper motions, which are generally too small forthe stars to have been included in previous catalogs of high-velocitystars. The same selection process is then extended to spectral type Fstars, in order to both provide a companion sample and investigatewhether the hypothetical high-velocity, metal-rich population continuesto later spectral types. Of the presented list of 371 stars withconfirmed proper motions, 168 are of A and B spectral types. Photometricand spectroscopic observations of these stars are required to eliminatethose with misclassified spectra and convert proper motions into spacevelocities. The identification of type of stars is important forunderstanding apparent exceptions to the correlation between stellarages, metal abundances, and kinematic properties.
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Individual observations of AG Phe.
Not Available
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Light Elements of AG Phoenicis
Not Available
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Contact binaries . III. Early-type systems.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978AJ.....83..288E&db_key=AST
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59th Name-List of Variable Stars
Not Available
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New Bright Southern Variable Stars
Not Available
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A finding list of early-type stars near the south galactic pole.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..338S&db_key=AST
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INHABITED SKY
