Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
Extended Strömgren Photoelectric Photometry in NGC 752
Photoelectric photometry on the extended Strömgren system (uvbyCa)is presented for 7 giants and 21 main-sequence stars in the old opencluster NGC 752. Analysis of the hk data for the turnoff stars yields anew determination of the cluster mean metallicity. From 10 single-starmembers, [Fe/H]=-0.06+/-0.03, where the error quoted is the standarderror of the mean and the Hyades abundance is set at [Fe/H]=+0.12. Thisresult is unchanged if all 20 stars within the limits of the hkmetallicity calibration are included. The derived [Fe/H] is in excellentagreement with past estimates, using properly zeroed m1 data,transformed moderate-dispersion spectroscopy, and recent high-dispersionspectroscopy.
| 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
| Red giants in open clusters. VIII. NGC 752
The results of an 18-year radial-velocity survey of 30 red giants in thefield of the open cluster NGC 752 are presented. The membership of 15stars is confirmed. Four spectroscopic binaries have been discoveredamong the members and three orbits have been determined for H75, 110 and208, with periods of 3321, 127 and 5276 days respectively. The binaryfrequency (27%) is normal. A search for additional members in a widesurrounding area (2degr ) yielded two possible new members: both areclump red giant candidates. The red giant distribution in thecolour-magnitude diagram is somewhat unusual, with a clump containing 8stars and a second, fainter feature extending to the blue, defined by 3or 4 stars, which is not accounted for by theoretical isochrones. Basedon observations collected at the Haute-Provence Observatory (France)
| Classification of Population II Stars in the Vilnius Photometric System. II. Results
The results of photometric classification of 848 true and suspectedPopulation II stars, some of which were found to belong to Population I,are presented. The stars were classified using a new calibrationdescribed in Paper I (Bartkevicius & Lazauskaite 1996). We combinethese results with our results from Paper I and discuss in greaterdetail the following groups of stars: UU Herculis-type stars and otherhigh-galactic-latitude supergiants, field red horizontal-branch stars,metal-deficient visual binaries, metal-deficient subgiants, stars fromthe Catalogue of Metal-deficient F--M Stars Classified Photometrically(MDPH; Bartkevicius 1993) and stars from one of the HIPPARCOS programs(Bartkevicius 1994a). It is confirmed that high galactic latitudesupergiants from the Bartaya (1979) catalog are giants or even dwarfs.Some stars, identified by Rose (1985) and Tautvaisiene (1996a) as fieldRHB stars, appear to be ordinary giants according to our classification.Some of the visual binaries studied can be considered as physical pairs.Quite a large fraction of stars from the MDPH catalog are found to havesolar metallicity. A number of new possible UU Herculis-type stars, RHBstars and metal-deficient subgiants are identified.
| A catalogue of [Fe/H] determinations: 1996 edition
A fifth Edition of the Catalogue of [Fe/H] determinations is presentedherewith. It contains 5946 determinations for 3247 stars, including 751stars in 84 associations, clusters or galaxies. The literature iscomplete up to December 1995. The 700 bibliographical referencescorrespond to [Fe/H] determinations obtained from high resolutionspectroscopic observations and detailed analyses, most of them carriedout with the help of model-atmospheres. The Catalogue is made up ofthree formatted files: File 1: field stars, File 2: stars in galacticassociations and clusters, and stars in SMC, LMC, M33, File 3: numberedlist of bibliographical references The three files are only available inelectronic form at the Centre de Donnees Stellaires in Strasbourg, viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5), or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| DDO Metal Abundances of High-Luminosity Late-Type Stars in Galactic Open Clusters
Results from UBV and DDO photometry are presented for 54 high-luminositylate-type stars in the fields of 23 open clusters. The probability ofcluster membership for each observed star is evaluated using twoindependent photometric criteria. It is found that 32 stars are verylikely cluster members, the remaining ones being almost certainly fieldobjects. The recently improved calibrations of the DDO system have beenused to derive MK spectral types, effective temperatures, andmetallicities, while E(B-V) color excesses have been determined throughknown photometric and spectroscopic procedures. The DDO metallicitiesrange between values typical of moderately metal-poor ([Fe/H]=~ -0.3) tomoderately metal-rich ([Fe/H] =~ 0.2) clusters. The masses of thecluster giants range between 1 and 4 solar masses, with the scatterwithin a cluster being less than 1 solar mass. (SECTION: StellarClusters and Associations)
| A photometric and radial-velocity analysis of the intermediate-age open cluster NGC 752
Using all available proper-motion and radial-velocity data, includingnew radial-velocity observations obtained for this investigation,probable members of the open cluster NGC 752 have been identified.Photoelectric data on six systems have been transformed and collated toform an internally consistent sample on the BV system. Binaries havebeen identified using photometric and radial-velocity data, including aphotographic survey for variability and the radial-velocity observationsof this study. Analysis of the data leads to the following clusterparameters and their probable errors: E(B - V) = 0.035 plus or minus0.005 mag, Fe/H = -0.15 plus or minus 0.05 dex, and (m - M) = 8.25 plusor minus 0.10 mag. The spread in color among stars in thecolor-magnitude diagram (cmd) along the main sequence from the turnoffto the unevolved main sequence is the consequence of a rich populationof binaries. Due to its age and the comprehensive data available for thecluster, NGC 752 provides an ideal test of a variety of evolutionaryphenomena. Comparison with theoretical isochrones normalized in aninternally consistent manner leads to the conclusion that the morphologyand distribution of stars in the cmd can best be matched using modelsthat include convective overshoot, particularly those of Schaller et al.(1992, A&AS, 96, 269). Despite their differences, the traditional andthe overshoot isochrones both imply very similar ages, 1.9 plus or minus0.2 Gyr and 1.7 plus or minus 0.1 Gyr, respectively, for the cluster.The Li abundances for the giants confirm that the giant branch isdominated by clump stars and first-ascent giants below the luminosity ofthe clump. The position and size of the Li dip among the main-sequencestars, compared to the Hyades, is readily explained by stellar evolutionwith convective overshoot. It is predicted that among turnoff stars inthe intermediate-age range Li will cease to be a unique function of ageat a given color. Chromospheric flux is shown to be a well-definedfunction of color for single, unevolved stars, identical to that foundfor the Hyades, and the relation for NGC 752 falls within theVaughan-Preston gap. However, the slope of the relation requires thatincreasing color implies increasing age for the bluer portion of theweak-emission boundary. The combined effect of small samples, randomerrors, emission limits, a possible selection bias in favor of turnoffstars, and metallicity corrections is to render highly questionable anyinterpretation of time-variable star formation within the Galaxy basedupon chromospheric ages.
| Evolved GK stars near the Sun. 2: The young disk population
From a sample of nearly 2000 GK giants a group of young disk stars withwell determined space motions has been selected. The zero point of theluminosity calibrations, both from the ultraviolet flux (modifiedStroemgren system) and that in the region of 4200 to 4900 A (DDOsystem), show a discontinuity of about a half magnitude at the border ofthe young disk and old disk domains. The population separation is basedon the space velocity components, which are also an age discriminant,with the population interface near 2 x 109 yr, based onmodels with convective overshoot at the core. This age corresponds togiant masses near 1.7 solar mass, near the critical mass separating theyoung stars that do not burn helium in degenerate cores from older starsthat do. Ten percent of both populations show CN anomalies in that thederived value of P(Fe/H) from CN (Cm) and fromFe(M1) differ by more than 0.1 dex and the weak and strong CNstars occur equally in the old disk but the weak CN stars predominate inthe young disk. Peculiar stars, where flux distortions affect theluminosity calibrations, are of the CH+(Ba II) and CH-(weak G band)variety and represent less than 1% of the stars in both populations. Theyoung disk giants are restricted to ages greater than about109 yr, because younger stars are bright giants orsupergiants (luminosity class 2 or 1), and younger than about 2 x109 yr, because the old disk-young disk boundary occurs near1.7 solar mass. The distribution of heavy element abundances, P(Fe/H),for young disk giants is both more limited in range (+/- 0.4 dex) and isskewed toward higher abundances, compared with the nearly normaldistribution for old disk giants. The distribution of (U,V) velocityvectors gives (U,V,W) and their dispersions = (+17.6 +/- 18.4, -14.8 +/-8.4, -6.9 +/- 13.0) and (+3.6 +/- 38.4, -20.7 +/- 27.5, -6.7 +/-17.3)km/s for young and old disk giants, respectively.
| Multicolour photoelectric photometry of the open cluster NGC 752
In the open cluster NGC 752, 89 stars are observed in the Vilniusseven-color photometric system, including probable members fainter thanobserved hitherto. Spectral classification of observed stars are madeand individual reddening values are determined. The mean reddening ofthe cluster stars is equivalent E(B - V) = 0.025 m. By fitting on colorindex-magnitude diagrams the cluster Main Sequence with the Hyades onethe distance modulus (m - M)0 = 8.15 +/- 0.15 m is found. For 11 redgiant members of the cluster absolute magnitudes are derived andcompared with ones of the standard calibration. It is obtained that thecluster giants are on average 0.6 m fainter than giants of thecorresponding spectral class in the solar vicinity.
| Metallicities and radial velocities of old open clusters
Medium resolution spectra of giant stars in 24 open clusters with agesgreater than about 1 Gyr have been obtained and analyzed to provideradial velocities accurate to 10-15 km/s and (Fe/H) metallicitiesaccurate to 0.15 dex. The radial velocities of the older cluster systemsare consistent with those expected from the reflex of solar motion andsimple Galactic rotation. The cluster kinematics suggest strongly thatthey are drawn from the old thin disk stellar population. An abundancegradient in the Galactic disk of -0.09 +/- 0.02 dex/kpc is found. Thisgradient is in good agreement with that found for samples of youngeropen clusters, suggesting that there has been little change in theGalactic radial abundance gradient over time. The cluster sample showsno correlation between age and metallicity, regardless of Galactocentricradius. The clusters show an unexpected correlation between the Mg linestrength and age of the cluster at a fixed metallicity. Possible reasonsfor this are discussed.
| A catalogue of Fe/H determinations - 1991 edition
A revised version of the catalog of Fe/H determinations published by G.Cayrel et al. (1985) is presented. The catalog contains 3252 Fe/Hdeterminations for 1676 stars. The literature is complete up to December1990. The catalog includes only Fe/H determinations obtained from highresolution spectroscopic observations based on detailed spectroscopicanalyses, most of them carried out with model atmospheres. The catalogcontains a good number of Fe/H determinations for stars from open andglobular clusters and for some supergiants in the Magellanic Clouds.
| The studies of proper motions in the regions of open clusters. II - NGC 752
Relative proper motions of 1777 stars in the region of the open clusterNGC 752 have been determined from the PDS measurements of eleven Pulkovonormal astrograph plates. In a 110-arcmin-diameter circle around thecluster, 175 stars have membership probabilities P greater than 0percent. The total number of cluster stars, obtained by weighting themwith membership probabilities, reaches 130. The catalog of propermotions is complete down to m(pg) = 150 mag, the limiting value is 154mag. The average standard error of the catalog proper motions variesfrom + or - 000075 arcsec/yr to + or - 00011 arcsec/yr for the rest. Theluminosity function for cluster stars shows a deficiency of faint stars.
| Radial velocities of more old open clusters
Moderate-resolution CCD spectra in the Mg b region of red giants in 13old or metal-poor open clusters were obtained with the kitt Peak 2.1-mtelescope. Radial velocities for these giants, measured bycross-correlation techniques, are accurate to 10 km/s. For the sixclusters in the sample with previous measurements, the velocities are ingood agreement with published values. Results are presented for sevenclusters (NGC 1193, NGC 1817, NGC 6819, NGC 7142, Be 21, King 8, IC 166)with no previous radial-velocity measurements. The majority of clustersin the sample, supplemented with ten more clusters older than 1 Gyrwhich have published velocities, show radial velocities which areconsistent with those expected from the reflex of solar motion andsimple galactic rotation. A few of the clusters, including the newlymeasured NGC 1193 and NGC 1817, show surprisingly large radialvelocities, indicating significant deviation from the general rotationof the remaining old cluster system.
| Carbon isotope ratios and lithium abundances in open cluster giants
New high-resolution, high S/N spectra of CN lines at 8000 A and Li linesat 6707 A have been obtained for giants in about 20 Galactic openclusters and C-12/C-13 ratios and Li abundances determined for thesestars. The ages of the clusters vary from about 50 million years to 5billion years, and their turn-off masses vary from 1 solar mass to about6 solar masses. The ages and turn-off masses were determined by fittingtheoretical isochrones to the cluster color-magnitude diagrams.Correlation of the isotope ratio and the Li abundances with the clusterturn-off masses indicates the following: (1) the C-12/C-13 ratioincreases steeply with the turn-off mass until a mass of approximately2.2 solar masses when the ratio levels off abruptly to a value near 26;(2) older clusters with turn-off masses lower than about 2.2 solarmasses in general exhibit C-12/C-13 ratios that are considerably lowerthan the theoretically predicted values while those with larger turn-offmasses show ratios close to standard predictions; and (3) no strongcorrelation exists between the Li abundances and the cluster turn-offmass, and the Li abundances in giants are, in general, lower thantheoretically predicted values. Various theories to explain the observedabundance trends are discussed.
| Lithium in giant stars in NGC 752 and M67
Spectra of giant stars in the intermediate-age galactic cluster NGC 752and in the old cluster M67 were studied for the presence of Li I 6707 A.The lithium feature is not present in any of the M67 giants observed;this may be because these giants evolve from progenitors in the regionof the main-sequence lithium dip. While lithium is not present in mostNGC 752 giants, the feature is strong in Heinemann 77 and 208. Theabundances are log epsilon (Li) = + 1.1 and + 1.4, respectively.
| Washington photometry of open cluster giants - The metal-rich clusters
Abundances of more than one hundred giants in a large sample ofmetal-rich open clusters in the Galaxy are investigated with Washingtonphotometry. Most of these clusters have no high-dispersion spectroscopicabundance determinations. A revision of the empirical abundancecalibrations for Population I giants, based on a much improved data setover previous calibrations, is first presented. The M-T(1) (Feabundance) calibration changes slightly for stars with Fe/H of about-0.5. The C-M (Fe + CN abundance) calibration is substantially alteredfor abundances above solar. The net effect brings the two abundanceindices into close agreement and eliminates the apparent CN enhancementspreviously determined for several open clusters. An enhanced sensitivityto Fe abundance is found for both the M - T(1) and especially the C - Mindex over that determined in previous investigations. Indeed, Delta(C -M) has an Fe abundance sensitivity that exceeds any other photometricabundance index. In view of the relative rarity of CN strengthvariations in Pop I giants, this index is most useful as a metallicityindicator for these stars. Abundances with an uncertainty of about 0.1dex are derived for a total of 18 open clusters observed with theWashington system. The abundances are generally in good agreement withprior abundance analyses. No strong evidence is found for CN variationsor anomalies in any of the clusters. A comparison with Population Ifield giants shows that the open cluster giants have normal CNabundances for their FE abundances.
| Positions and Magnitudes in the Area of the Open Cluster NGC752
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985RMxAA..11..103S&db_key=AST
| A catalogue of Fe/H determinations, 1984 edition
The present version of the Cayrel de Strobel et al. (1981) catalog ofFe/H abundance ratio determinations contains 1921 values for 1035 stars,which represents an augmentation over the previous publication of 48 and47 percent, respectively. In addition, the literature search conductedis complete up to December, 1983. Stellar metal abundance, effectivetemperature, spectroscopic gravity, spectral type, and photometricindices are covered.
| A DDO astrophysical study of NGC 752
DDO intermediate-band photometry of 11 red giants in the field of thesparsely populated open cluster NGC 752 is reported. Physical propertiesof the 11 stars, such as heavy-element abundances, surface gravities,and effective temperatures, are determined. A cluster age of 1.1 plus orminus 0.1 billion years is obtained by means of a comparison withPatenaude's (1978) theoretical isochrones. A true distance modulus of7.9 plus or minus 0.2 mag is estimated for NGC 752, along with a truedistance of 380 plus or minus 40 pc, an Fe/H abundance ratio of 0.0 plusor minus 0.1, and a red-giant mean mass of 1.5 plus or minus 0.2 solarmasses. It is concluded that NGC 752 is on the metal-rich side of thedistribution of intermediate and old open clusters, at about the sameFe/H value as NGC 7789 and halfway between NGC 2477 and NGC 2243.
| (R-I) colors of cepheids and yellow supergiants in open clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976ApJ...203..466S&db_key=AST
| Four-color and H-beta photometry of open clusters - V - NGC 752.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..946C&db_key=AST
| Photoelectric Photometry of 1160 Late-Type Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....2....1D&db_key=AST
| Vitesses radiales dans la region de l'amas NGC 752.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&A.....4..404R&db_key=AST
| Scanner Abundance Studies. I. an Investigation of Supermetallicity in Late-Type Evolved Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...157.1279S&db_key=AST
| Radial Velocities of Yellow Giants in Four Galactic Clusters
Not Available
| Photometry of the galactic cluster NGC 752
Not Available
| A catalogue of proper motions of stars in 13 open clusters and in their vicinity.
Not Available
| The Spectrum-Luminosity Diagram for NGC 752.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1955ApJ...121..454R&db_key=AST
| Magnitudes and Colors in NGC 752.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1953ApJ...117..356J&db_key=AST
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
| Созвездие: | Андромеда |
| Прямое восхождение: | 01h57m38.95s |
| Склонение: | +37°46'12.4" |
| Видимая звёздная величина: | 9.037 |
| Собственное движение RA: | 9 |
| Собственное движение Dec: | -10.5 |
| B-T magnitude: | 10.293 |
| V-T magnitude: | 9.141 |
Каталоги и обозначения:
|
INHABITED SKY
