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Golden Ratio Sinusoidal Sequences and the Multimode Pulsation of the δ Sct Star V784 Cassiopeiae
Non periodic ordered sequences obtained by production rules in formalgrammars are applied to the analysis of the multi-periodicity of theδ-Scuti type variable star V784 Cas. An artificial light curvefor V784 Cas is generated by a non deterministic derivation in acontext-sensitive grammar by concatenation of two sinusoidal fragmentsfollowing certain word sequences. The two basic building blocksrepresent temporal segments in a golden ratio and the number of long andshort segments in a word are also in a golden ratio.
| Observations of Star-Forming Regions with the Midcourse Space Experiment
We have imaged seven nearby star-forming regions, the Rosette Nebula,the Orion Nebula, W3, the Pleiades, G300.2-16.8, S263, and G159.6-18.5,with the Spatial Infrared Imaging Telescope on the Midcourse SpaceExperiment (MSX) satellite at 18" resolution at 8.3, 12.1, 14.7, and21.3 μm. The large angular scale of the regions imaged (~7.2-50deg2) makes these data unique in terms of the combination ofsize and resolution. In addition to the star-forming regions, twocirrus-free fields (MSXBG 160 and MSXBG 161) and a field near the southGalactic pole (MSXBG 239) were also imaged. Point sources have beenextracted from each region, resulting in the identification over 500 newsources (i.e., no identified counterparts at other wavelengths), as wellas over 1300 with prior identifications. The extended emission from thestar-forming regions is described, and prominent structures areidentified, particularly in W3 and Orion. The Rosette Nebula isdiscussed in detail. The bulk of the mid-infrared emission is consistentwith that of photon-dominated regions, including the elephant trunkcomplex. The central clump, however, and a line of site toward thenorthern edge of the cavity show significantly redder colors than therest of the Rosette complex.
| The multimode pulsation of the delta Scuti star V784 Cassiopeae
We present an analysis of new Johnson and Strömgren photometric andmedium-resolution spectroscopic observations of the delta Scuti typevariable star V784 Cassiopeae. The data were obtained in threeconsecutive years between 1999 and 2001. The period analysis of thelight curve resulted in the detection of four frequencies ranging from9.15 d-1 to 15.90 d-1, while there is a suggestionfor more, unresolved frequency components, too. The mean Strömgrenindices and Hipparcos parallax were combined to calculate the followingphysical parameters: < T_eff >= 7100 +/- 100 K, log g= 3.8 +/-0.1, M_bol= 1\fm50 +/- 0\fm15. The position of the star in the HRdiagram was used to derive evolutionary mass and age yielding to aconsistent picture of an evolved delta Scuti star with a mixture ofradial plus non-radial modes. Based on spectroscopic data obtained atthe David Dunlap Observatory, University of Toronto and photometricobservations obtained at the Sierra Nevada Observatory, IAA-CSIC.
| 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
| ROSAT HRI survey of the open cluster Stock 2
We have obtained two deep HRI observations toward the open cluster Stock2 in order to assess the X-ray luminosity level of the 112high-probability cluster members falling in the area we have surveyed.Members have been selected on the basis of the result of a recent propermotion study based on the same photographic material and the samereduction scheme as the GSC-II project. We have reached a limitingsensitivity of L_X ~ 3 x 1029 erg/sec for Stock 2 members andhave detected 19 X-ray sources. The attained limiting sensitivity hasprevented a complete sampling of the coronal emission level of Stock 2,and we have detected only three solar-type and one B9V members. We havederived the X-ray luminosity function for the Stock 2 stars in the 0.43< (B-V)_o < 0.8 color range and have compared it with the X-rayluminosity functions of the dG members of Praesepe, Hyades and Pleiadesopen clusters. While the limiting sensitivity of our observations andthe present uncertainties in Stock 2 and other cluster distances do notallow to derive firm conclusion, yet, our data indicate that the coronalemission level of Stock 2 solar-type stars is more similar to that ofthe Hyades (or the Praesepe) than to the Pleiades one. This in turnsuggests that either Stock 2 is older than previously reported or thatthe current age-rotation-activity paradigm need to be revised. In thislatter case Stock 2 would likely belong to the small group of openclusters (Praesepe, NGC6333 and IC 4675) for which recent X-ray surveysindicate a more complex age-rotation-activity relation than currentlythought.
| A catalog of rotational and radial velocities for evolved stars
Rotational and radial velocities have been measured for about 2000evolved stars of luminosity classes IV, III, II and Ib covering thespectral region F, G and K. The survey was carried out with the CORAVELspectrometer. The precision for the radial velocities is better than0.30 km s-1, whereas for the rotational velocity measurementsthe uncertainties are typically 1.0 km s-1 for subgiants andgiants and 2.0 km s-1 for class II giants and Ib supergiants.These data will add constraints to studies of the rotational behaviourof evolved stars as well as solid informations concerning the presenceof external rotational brakes, tidal interactions in evolved binarysystems and on the link between rotation, chemical abundance and stellaractivity. In this paper we present the rotational velocity v sin i andthe mean radial velocity for the stars of luminosity classes IV, III andII. Based on observations collected at the Haute--Provence Observatory,Saint--Michel, France and at the European Southern Observatory, LaSilla, Chile. Table \ref{tab5} also available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The Hα behavior in bright giant stars.
We report high resolution spectroscopic observations of the Hαline profile for a sample of 32 bright giant stars with spectral typebetween F3II and G5II. By studying the link between the Hαbehavior and the stellar rotation in such class of luminosity we havefound no clear evidence that the rotational discontinuity establishedaround F9II is related with the Hα profiles. No emission features,neither time variations or asymmetries on the Hα line profileshave been detected for the bright giants analysed in the present work.
| 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)
| New UBVRI photometry for 900 supergiants
A description is presented of the results obtained in connection with asystematic program of supergiant photometry on the Johnson UBVRI system.During the eight years after the start of the program, almost 1000 starshave been observed, about 400 three or more times each. The originalselection of stars used the spectral type catalog of Jaschek et al.(1964) to choose supergiants. Since observations were possible from bothChile and Canada, no declination limits were imposed, and no particularselection criteria were imposed other than to eliminate carbon stars.These are so red as to require enormous extrapolations of thetransformation equations.
| A spectrophotometric survey of stars along the Milky Way. IV
In the present paper a catalogue of spectrophotometric quantities,spectral types, monochromatic magnitudes and colour equivalents is givenfor all stars brighter than the magnitude m4400 = 10.5 in aregion of the Milky Way in Perseus. No absorption is found for starscloser than about r = 100 pc. The absorbing clouds are situated atdistances closer than 1 kpc and at about 2.5 kpc in the local arm andthe Perseus arm, respectively. The space between the two arms is freefrom absorption. It is also concluded that the Perseus arm continuesbeyond l = 140 deg, containing not only hydrogen gas but also dust to atleast l = 150 deg), while the content of OB stars decreases abruptly atl = 140 deg.
| Evolved stars in open clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976ApJS...30..451H&db_key=AST
| Photometric and Polarimetric Observations of the Nearby Strongly Reddened Open Cluster Stock 2
Abstract image available at:http://adsabs.harvard.edu/abs/1967ApJ...147..988K
| La mesure des vitesses radiales au prisme objectif - X - 4e liste de vitesses radiales déterminées au prisme objectif à vision directe
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| Takýmyýldýz: | Zincirli Prenses |
| Sað Açýklýk: | 02h19m41.53s |
| Yükselim: | +60°00'47.0" |
| Görünürdeki Parlaklýk: | 7.196 |
| Uzaklýk: | 240.385 parsek |
| özdevim Sað Açýklýk: | -9.3 |
| özdevim Yükselim: | -9.9 |
| B-T magnitude: | 8.449 |
| V-T magnitude: | 7.3 |
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