Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
Red giants in open clusters. XIV. Mean radial velocities for 1309 stars and 166 open clusters
Context: Radial velocities have proved to be an efficient method formembership determination if there are at least 2 or 3 red giants in acluster. They are necessary for galactic studies, but are still missingfor many open clusters. Aims: We present the final catalogues of along-term observing programme performed with the two coravelspectrovelocimeters for red giants in open clusters. The main aims wereto detect spectroscopic binaries and determine their orbital parameters,determine the membership, and compute mean velocities for the stars andopen clusters. Methods: We computed weighted mean radial velocities for1309 stars from 10 517 individual observations, including the systemicradial velocities from spectroscopic orbits and for cepheids. Results:The final results are contained in three catalogues collecting 10 517individual radial velocities, mean radial velocities for 1309 redgiants, and mean radial velocities for 166 open clusters among whichthere are 57 new determinations. We identified 891 members and 418non-members. We discovered a total of 288 spectroscopic binaries, amongwhich 57 are classified as non-members. In addition 27 stars were judgedto be variable in radial velocities and they are all red supergiants. Conclusions: The present material, combined with recent absolute propermotions, will permit various investigation of the galactic distributionand space motions of a large sample of open clusters. However, thedistance estimates still remain the weakest part of the necessary data.This paper is the last one in this series devoted to the study of redgiants in open clusters based on radial velocities obtained with thecoravel instruments.Based on observations collected at the Haute-Provence Observatory(France) and on observations collected with the Danish 1.54-m telescopesat the European Southern Observatory, La Silla, Chile. Full Tables [seefull textsee full textsee full textsee full textsee full text] to [seefull textsee full textsee full textsee full textsee full text] are onlyavailable and Tables [see full textsee full textsee full textsee fulltextsee full text] and [see full textsee full textsee full textsee fulltextsee full text] are also available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/485/303
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| SB9: The ninth catalogue of spectroscopic binary orbits
The Ninth Catalogue of Spectroscopic Binary Orbits(http://sb9.astro.ulb.ac.be) continues the series of compilations ofspectroscopic orbits carried out over the past 35 years by Batten andcollaborators. As of 2004 May 1st, the new Catalogue holds orbits for2386 systems. Some essential differences between this catalogue and itspredecessors are outlined and three straightforward applications arepresented: (1) completeness assessment: period distribution of SB1s andSB2s; (2) shortest periods across the H-R diagram; (3)period-eccentricity relation.
| An optical study of X-ray sources in the old open clusters NGC 752 and NGC 6940
We observed the optical counterparts of X-ray sources in the old openclusters NGC 752 and NGC 6940 to search for the origin of the X-rays.The photometric variability reported earlier for the blue straggler H209 is not confirmed by our light curves, nor is an indication forvariability seen in the spectra; thus its X-rays remain unexplained. TheX-rays of VR 111 and VR 114 are likely not a result of magnetic activityas these stars lack strong Ca II H&K emission, while in VR 108 thelevel of activity could be enhanced. The short-period binary H 313 is aphotometric variable; this supports the interpretation that it is amagnetically active binary. From the detection of the Li I 6707.8Å line, we classify the giant in VR 84 as a first-ascent giant;this leaves its circular orbit unexplained. As a side-result we reportthe detection of Li I 6707.8 Å in the spectrum of the giant H 3and the absence of this line in the spectrum of the giant H 11; thisclassifies H 3 as a first-ascent giant and H 11 as a core-helium-burningclump star, and confirms the faint extension of the red-giant clump inNGC 752. Based on observations made with the Jacobus Kapteyn Telescopeand the William Herschel Telescope operated on the island of La Palma bythe Isaac Newton Group in the Spanish Observatorio del Roque de losMuchachos of the Instituto de Astrofisica de Canarias.
| Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 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
| Soft X-ray emission from intermediate-age open clusters: NGC 6940.
We present the results of soft X-ray observations of theintermediate-age open cluster NGC 6940 performed with the ROSAT PSPC. Wedetected 18 sources, four of which are identified with member stars ofthe cluster and five with active field stars. Another source isidentified with an active giant star that could belong to the cluster,although it is not classified as a cluster member. The remaining eight,most likely of extragalactic nature, need to be identified throughoptical follow-up. As in the case of old clusters such as M 67 and NGC752, a high fraction of the detected members are binaries: in NGC 6940three out of four of the identified members are among the only sixbinaries known in the cluster. All four sources have X-ray luminositiestypical of RS CVn binaries. However, only two of the three detectedbinaries have system characteristics typical of active X-ray binaries.The high X-ray luminosity of the other two sources needs to beexplained. All four identified members are red giants, in agreement withthe presence of a saturation level. The four field stars identified ascounterparts of X-ray sources are all very active, with X-rayluminosities in the range 10^29^-10^30^erg/s, and deserve furtheroptical investigation. We confirm the results found in other old openclusters, i.e. that binaries are still very active coronal sources at anage greater than 1Gyr, and that good spatial resolution images in theX-ray band are a powerful tool to investigate their evolution inclusters of different ages.
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| Tidal circularization and the eccentricity of binaries containing giant stars.
We show that the predicted amount of tidal circularization in a detachedbinary containing a giant is, according to Zahn's theory, determinedonly by observable properties of its orbit, and a single integral alongthe giant's stellar evolutionary sequence. We perform these integrals,display them graphically, and provide fitting formulae. Spectroscopicbinaries in open clusters are ideal for testing the theory of tidalcircularization, since the stars' mass, luminosity and temperature canall be determined with precision. We apply our calculations to 28binaries in 12 open clusters. We show that the orbital parameters of allcan be understood within the circularization theory, and that the mixinglength parameter in Zahn's theory is well constrained:1<~α<~3. We show that the orbital period alone does notseparate circular and eccentric orbits, and point out that theeccentricity of the orbit can sometimes distinguish between giant starsand core helium burning `clump' stars even in circumstances where thisis difficult spectroscopically. In some special types of binary systems,the circularization is sensitive to aspects of stellar evolution theorythat are not well understood: the maximum depth of penetration of theouter convective zone, the radius at first dredge-up, the maximum radiiof stars at the tips of the giant and asymptotic giant branches. It thusappears that the orbits of binaries containing giants may prove to be auseful tool for studying stellar evolution.
| Red giants in open clusters. I - Binarity and stellar evolution in five Hyades-generation clusters: NGC 2447, 2539, 2632, 6633, and 6940
The present analysis for membership-determination and binary-detectionof radial velocity observations for 62 red giant stars in the HyadeslikeNGC 2447, 2539, 2632, 6633, and 6940 open clusters has yielded a binarypercentage of the order of 25-33 percent. Twelve orbits have beendetermined, and two triple systems identified. At least nine of the tenstars found in the Hertzsprung gap are composite binaries of the (gK +dA) type; the radial velocity dispersion in each cluster is close to thevalue expected on the basis of the virial theorem, assuming typicalvalues of the total mass of 1000 solar masses, and of a half-mass radiusof 3 pc.
| Galactic cluster star radial velocities obtained with a focal reducer field spectrograph. I - The clusters IC 1805, NGC 2287, NGC 2548, IC 4665, NGC 6633, NGC 6940 and NGC 7092
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...62..301G&db_key=AST
| The Radial Velocity of NGC 6940
Not Available
| Relative proper motions of stars in the region of the open cluster NGC 6940.
Abstract image available at:http://adsabs.harvard.edu/abs/1957AJ.....62..175V
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
| Созвездие: | Лисичка |
| Прямое восхождение: | 20h34m22.92s |
| Склонение: | +28°21'41.3" |
| Видимая звёздная величина: | 10.459 |
| Собственное движение RA: | -2.4 |
| Собственное движение Dec: | -8.4 |
| B-T magnitude: | 11.289 |
| V-T magnitude: | 10.528 |
Каталоги и обозначения:
|
