Садржај
Слике
Уплоадјуј своје слике
DSS Images Other Images
Везани чланци
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.
| The Vienna-KPNO search for Doppler-imaging candidate stars. I. A catalog of stellar-activity indicators for 1058 late-type Hipparcos stars
We present the results from a spectroscopic Ca ii H&K survey of 1058late-type stars selected from a color-limited subsample of the Hipparcoscatalog. Out of these 1058 stars, 371 stars were found to showsignificant H&K emission, most of them previously unknown; 23% withstrong emission, 36% with moderate emission, and 41% with weak emission.These spectra are used to determine absolute H&K emission-linefluxes, radial velocities, and equivalent widths of theluminosity-sensitive Sr ii line at 4077 Ä. Red-wavelengthspectroscopic and Strömgren y photometric follow-up observations ofthe 371 stars with H&K emission are used to additionally determinethe absolute Hα -core flux, the lithium abundance from the Li i6708 Å equivalent width, the rotational velocity vsin i, theradial velocity, and the light variations and its periodicity. Thelatter is interpreted as the stellar rotation period due to aninhomogeneous surface brightness distribution. 156 stars were found withphotometric periods between 0.29 and 64 days, 11 additional systemsshowed quasi-periodic variations possibly in excess of ~50 days. Further54 stars had variations but no unique period was found, and four starswere essentially constant. Altogether, 170 new variable stars werediscovered. Additionally, we found 17 new SB1 (plus 16 new candidates)and 19 new SB2 systems, as well as one definite and two possible new SB3systems. Finally, we present a list of 21 stars that we think are mostsuitable candidates for a detailed study with the Doppler-imagingtechnique. Tables A1--A3 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| The ROSAT All-Sky Survey of Active Binary Coronae. III. Quiescent Coronal Properties for the BY Draconis--Type Binaries
We present X-ray observations of 35 active late-type BY Draconis dwarfbinary systems and 28 evolved binary systems, similar in nature to theRS Canum Venaticorum systems, obtained with the Position SensitiveProportional Counter (PSPC) during the ROSAT All-Sky Survey phase of themission. Of this sample, 52 targets were detected in exposures ofroughly 600 s or less. When these new data are combined with the earlierresults from Dempsey et al. (1993b), this survey represents the largestsample of active binary systems observed to date at any wavelength,including X-rays. We expand our investigation of how coronal properties(e.g., surface flux, luminosity, etc.) correlate with stellar parameters(e.g., rotation period, color, etc.) and confirm the conclusions ofDempsey et al. (1993b). Rotation period provides the best correlationwith X-ray surface flux with F_{{X}}~P^{-0.59+/-0.10}_{{rot}} for theentire sample. We find no evidence for a "basal" or nonmagnetic X-rayflux component. We model the low-resolution pulse-height spectra for 12systems with two-temperature thermal plasmas. The derived temperaturesfor the BY Dra systems are identical to those previously derived foractive evolved giants and subgiants in close binaries (Dempsey et al.1993c). We also show that the dependence of temperature and emissionmeasures on rotation period is the same for the dwarf, subgiant, andgiant binaries.
| The ROSAT All-Sky Survey of active binary coronae. I - Quiescent fluxes for the RS Canum Venaticorum systems
One hundred and thirty-six RS CV(n) active binary systems were observedwith the ROSAT Position Sensitive Proportional Counter (PSPC) during theAll-Sky Survey component of the mission. The entire sky was surveyed,which represents the largest sample of RS CV(n) systems observed to dateat any wavelength, including X-rays. X-ray surface fluxes for the RSCV(n) systems are found to lie in the range 10 exp 4 to 10 exp 8 ergs/sqcm seconds. Surface flux as a function of (B - V) color is reported. Adecrease in surface flux with increasing rotation period for the entiresample is observed. The rotation period provides the best stellar ororbital parameter to predict the X-ray surface flux level. The absenceof correlation of F(x) or L(x) with Gamma is noted due to the fact thatthe coronal heating mechanism for these active stars must be magnetic incharacter, and the magnetic field depends on the interaction betweenconvection and differential rotation inside the star. X-ray propertiesof the RS CV(n) systems with 6 cm radio and C IV UV emission systems iscompared.
| Amateur Variable Star Observing in Japan
Activities and publications of various astronomical groups in Japan aredescribed.
| The 70th Name-List of Variable Stars
Not Available
| Spectroscopic binaries near the north Galactic pole. XVII - HD 111425
Photoelectric radial-velocity measurements of HD 111425 from May 1980 toMarch 1988 are presented. The observations show that the source is adouble-lined spectroscopic binary. It is found that the components ofthe binary have types of about F8 V and G6 V and are in a 51-day orbitof moderate eccentricity.
| Photometric Detection of Eclipse in the Spectroscopic Binary HD 116093
Not Available
| Spectroscopic binaries near the North Galactic Pole. XVI - HD 116093
Photoelectric radial-velocity measurements show that HD 116093 is adouble-lined spectroscopic binary in a very eccentric 53-day orbit. Verylittle else is known about the system, but circumstantial evidence isconsistent with the hypothesis that the component's types are near to F3V and F8 V. If that is so, the orbit must be seen very nearly edge-on; asearch for eclipses is warranted and an ephemeris for them is given.
|
Додај нови чланак
Линкови у сродству са темом
Додај нови линк
Чланови следећих група \:
|
Посматрања и Астрометриски подаци
Каталог и designations:
|
