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From the Top to the Bottom of the Main Sequence: A Complete Mass Function of the Young Open Cluster M35
We present very deep and accurate photometry of the open cluster M35. Wehave observed this association in the Cousins R, I filters, togetherwith the Johnson V filter. We have covered a region of 27.5×27.5square arcmin, equivalent to a fifth of the total area of the cluster.The data range from Ic=12.5 to 23.5 mag, and the colorintervals are 0.4<=(V-I)c<=3.0,0.5<=(R-I)c<=2.5. Roughly, these values span from 1.6Msolar down to the substellar limit, in the case of clustermembers. By using the location of the stars on color-magnitude andcolor-color diagrams, we have selected candidate members of thiscluster. We have merged our sample with previously published data andobtained a color-magnitude diagram for the complete stellar populationof the cluster, covering the spectral range early B-mid M. Based on thedistribution of field and cluster stars in color-magnitude andcolor-color diagrams, we estimate that two-thirds of these candidatesare likely to be true members of M35. These stars approximately doublethe number of stars identified as candidate members of this cluster(~2700). We provide the photometry and accurate positions of thesestars. The deep photometry has allowed us to study the mass segregationwithin the cluster, the luminosity function, and mass function. We showthat in the magnitude range 13<=Ic<=22 there is areduced mass segregation, in opposition to what happens to higher massstars, where the mass segregation is stronger. The luminosity functionbehaves essentially as the one characteristic of the Pleiades,presenting a peak at Ic~19 mag (MI~9). Combiningour photometry with previous data corresponding to more massive stars,we find that the mass function increases monotonically, when plotted ina log-log form, until it reaches ~0.8 Msolar (α=2.59).It remains shallower for less massive stars (α=0.81 for 0.8-0.2Msolar), whereas a decrease is observed for stars close tothe substellar regime. These different behaviors suggest that at leastthree mechanisms play a role in the formation of stellar and substellarobjects. The total mass of the cluster is ~1600 Msolar in thearea covered by this study.
| Kinematics of Metal-poor Stars in the Galaxy. II. Proper Motions for a Large Nonkinematically Selected Sample
We present a revised catalog of 2106 Galactic stars, selected withoutkinematic bias and with available radial velocities, distance estimates,and metal abundances in the range -4.0<=[Fe/H]<=0.0. This updateof the 1995 Beers & Sommer-Larsen catalog includes newly derivedhomogeneous photometric distance estimates, revised radial velocitiesfor a number of stars with recently obtained high-resolution spectra,and refined metallicities for stars originally identified in the HKobjective-prism survey (which account for nearly half of the catalog)based on a recent recalibration. A subset of 1258 stars in this cataloghave available proper motions based on measurements obtained with theHipparcos astrometry satellite or taken from the updated AstrographicCatalogue (second epoch positions from either the Hubble Space TelescopeGuide Star Catalog or the Tycho Catalogue), the Yale/San Juan SouthernProper Motion Catalog 2.0, and the Lick Northern Proper Motion Catalog.Our present catalog includes 388 RR Lyrae variables (182 of which arenewly added), 38 variables of other types, and 1680 nonvariables, withdistances in the range 0.1 to 40 kpc.
| UBVI CCD photometry of M35 (NGC 2168)
UBVI CCD photometry has been obtained for the intermediate-age opencluster M35 (NGC 2168). From this new photometry we derived the clusterparameters (V_0 - M_V= 9.60 +/- 0.10 mag, E(B-V) = 0.255 +/- 0.024 mag),age (log t_age=8.3 +/-0.3) and a photometric abundance (Z ~ 0.008, i.e.[Fe/H] ~ - 0.3) from comparison with theoretical isochrones of thePadova group. A minimum binary frequency (35 +/- 5 per cent) wasestimated from the distribution of distance moduli of unevolved propermotion members. Faint photometric members were selected by usingdifferences in the reddening effect on colour indices.
| Colour excesses of F-G supergiants and Cepheids from Geneva photometry.
A reddening scale for F-G supergiants and Cepheids is presented.Supergiants with low reddenings or in clusters form the basis of thecalibration. In this sense, it is entirely empirical. The data have beenobtained in the Geneva photometric system. Comparisons with otherreddening scales show no disagreement. The only problem is with Fernie'sscale for Cepheids (1990), where a systematic trend exists. Its originis not clear. It is suggested to extend the number of supergiants withindependently obtained colour excesses in order to test the existence ofa possible luminosity dependence of the calibration. A period-colourrelation for Cepheids is deduced, on the basis of the present reddeningcorrections. It gives strong support for V473 Lyr being a secondovertone pulsator.
| Kinematics of metal-poor stars in the galaxy
We discuss the kinematic properties of a sample of 1936 Galactic stars,selected without kinematic bias, and with abundances (Fe/H) is less thanor equal to -0.6. The stars selected for this study all have measuredradial velocities, and the majority have abundances determined fromspectroscopic or narrow-/intermediate-band photometric techniques. Incontrast to previous examinations of the kinematics of the metal-poorstars in the Galaxy, our sample contains large numbers of stars that arelocated at distances in excess of 1 kpc from the Galactic plane. Thus, amuch clearer picture of the nature of the metal-deficient populations inthe Galaxy can now be drawn.
| Kinematics of Sandage-Fouts stars in three cardinal directions
V and (B - V) for 429, 442, and 427 stars are observed in the directionsof the anticenter, Cygnus, and the NGP, respectively, and DDO colors forthose stars G0 and later. The samples observed are ones for whichSandage and Fouts (1987) have published radial velocities. W, V, and Wcomponents of space velocity are derived from DDO distances withavailable proper motions. A clear correlation was found to exist betweenthe velocity dispersions and Fe/H with the dispersions decreasing asFe/H increases to about + 0.00, where V then becomes significantlynegative. The 'thick disk' component is clearly recognized, with sigma(W) approximately equal to 36 km/sec. In the 'old thin disk' and the'young thin disk', 43 percent and 42 percent of the stars have negativeV values, respectively.
| U, V, W velocity components for the old disk using radial velocities of 1295 stars in the three cardinal Galactic directions
New radial velocities are presented for 1295 stars chosen at random nearthe three cardinal Galactic directions of l = 180 deg, b = 0; l = 90deg, b = 0 deg; and b = 90 deg, giving the distribution in U, V, and W,respectively, from the radial velocities alone. The measurements weremade with the coude spectrograph of the Mount Wilson 100 in. Hookerreflector. The purpose of the program is to set limits on the densitynormalization in the solar neighborhood of the old thin disk, the oldthick disk, and the halo. Many more high-velocity stars are present inthe unbiased sample than expected from previous estimates of thenormalization. The data suggest the density ratios in the solarneighborhood to be about 90 percent, 10 percent, and about 0.5 percentfor the thin disk, thick disk, and halo populations, respectively.
| Estimation of spectral classifications for bright northern stars with interesting Stromgren indices
The purpose of this investigation is to provide spectroscopic observerswith finding lists of potentially interesting objects. From anunpublished UVBY catalogue of 7026 northern stars (mostly brighter than8.3m) 1094 objects with interesting combinations of UVBY indices havebeen selected. Most stars with post-HD classifications have beenexcluded, as well as late F dwarfs belonging to the intermediatepopulation II. For the 792 remaining stars estimated spectralclassifications are given. The techniques and experience from a previouspaper dealing with southern stars have been utilized here. Among thepredicted spectral classifications are 40 OB stars; 262 Ap, Am, or Fmstars; 16 supergiants of types A to G; 110 bright giants of types A to K(class II); 156 double stars or objects with composite spectra; 26 lateF dwarfs; 91 weak-lined dwarf and giant stars of types F to K, includingearly F-type population II field blue stragglers; and a few possiblefield horizontal branch stars, lambda Bootis-type stars, and late-typehalo giants.
| Relative proper motions in the region of the open cluster NGC 2168 (M35).
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..475C&db_key=AST
| Etoiles doubles nouvelles decouvertes a l'Observatoire de Nice (2eme serie).
Not Available
| A catalogue of proper motions of stars in 13 open clusters and in their vicinity.
Not Available
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Близнецы |
| Прямое восхождение: | 06h09m15.94s |
| Склонение: | +24°25'40.4" |
| Видимая звёздная величина: | 7.426 |
| Собственное движение RA: | 1.4 |
| Собственное движение Dec: | -3.8 |
| B-T magnitude: | 8.876 |
| V-T magnitude: | 7.546 |
Каталоги и обозначения:
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