תוכן
תמונות
הוסף תמונה שלך
DSS Images Other Images
מאמרים קשורים
Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Mira kinematics in the post-Hipparcos era
The complete data set of Mira variables from the 4th edition of theGeneral Catalog of Variable Stars was analyzed and supplemented by theproper motions and radial velocities presently available for Miras. Theresulting sample of 724 Miras with periods between 78 and 612 dayscontains proper motions reduced to the Hipparcos system, radialvelocities and V magnitudes. For each of 10 subgroups of Miras dividedaccording to their periods and spectral types, statistical parallaxeswere determined by application of five different methods. The meanabsolute magnitudes, the spatial velocities and their dispersions aswell as the elements of the Galactic orbits were computed as functionsof the periods. The (Mbol-< ~ g P) relation obtained wasfound to be considerably steeper than the PLR usually assumed for LMCMiras. For Miras in the period range 145-200 days, no significant netmotion radially outwards in the Galaxy as suggested by Feast &Whitelock (2000) was found. The predicted frequency of Miras wascomputed as a function of the visual magnitude.
| Polarimetry of 167 Cool Variable Stars: Data
Multicolor photoelectric polarimetry is presented for 167 stars, most ofwhich are variable stars. The observations constitute a data set thatfor some stars covers a time span of 35 yr. Complex variations are foundover time and wavelength and in both the amount of polarization and itsposition angle, providing constraints for understanding the polarizingenvironments in and around these cool stars.
| Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
| Infrared colours for Mira-like long-period variables found in the (Mȯ<~10-7 Msolar yr-1) Hipparcos Catalogue
Near-infrared, JHKL, photometry is presented for 193 Mira andsemi-regular variables that were observed by Hipparcos; periods,bolometric magnitudes and amplitudes are derived for 92 of them. Becauseof the way in which the Hipparcos targets were selected, this group ofstars provides a useful data base of Miras with low mass-loss rates(Mȯ<~10-7Msolaryr-1).Various period-colour relationships are discussed in detail. The colour,particularly BCK = 10.86 - 38.10 K (J - K)0 +64.16(J - K)20 - 50.72(J -K)30 + 19, K-L, at a given period is found todepend on the pulsation amplitude of the star. A comparison with modelssuggests that this is a consequence of atmospheric extension, in thesense that large-amplitude pulsators have very extended atmospheres andredder Mȯ<10-7Msolaryr-1, K-L and H-K but bluerJ-H than their lower amplitude counterparts. The stars with veryextended atmospheres also have higher values of K-[12] and hence highermass-loss rates. This finding provides further evidence for the causalconnection between pulsation and mass loss. Two sequences are identifiedin the Hp-K versus logP diagram (where Hp is the Hipparcos broad-bandmagnitude) at short periods (logP<2.35). At a given period these twogroups have, on average, the same pulsation amplitude, but differentJHKL colours and spectral types. The short-period stars in the bluersequence have similar near-infrared colours to the Miras found inglobular clusters. Long-term trends in the infrared light curves arediscussed for stars that have sufficient data.
| Mira kinematics from Hipparcos data: a Galactic bar to beyond the Solar circle
The space motions of Mira variables are derived from radial velocities,Hipparcos proper motions and a period-luminosity relation. Thepreviously known dependence of Mira kinematics on the period ofpulsation is confirmed and refined. In addition, it is found that Miraswith periods in the range 145-200d in the general Solar neighbourhoodhave a net radial outward motion from the Galactic Centre of75+/-18kms-1. This, together with a lag behind the circularvelocity of Galactic rotation of 98+/-19kms-1, is interpretedas evidence for an elongation of their orbits, with their major axesaligned at an angle of ~17° with the Sun-Galactic Centre line,towards positive Galactic longitudes. This concentration seems to be acontinuation to the Solar circle and beyond of the bar-like structure ofthe Galactic bulge, with the orbits of some local Miras probablypenetrating into the bulge. These conclusions are not sensitive to thedistance scale adopted. A further analysis is given of the short-period(SP) red group of Miras discussed in companion papers in this series. InAppendix A the mean radial velocities and other data for 842 oxygen-richMira-like variables are tabulated. These velocities were derived frompublished optical and radio observations.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| Lumnosity attenuation and distances of red giant stars
The Mv of M red variable stars is increased by the molecularTiO bands which grow from M0 to M10 in an inherent spectral darkeningsequence. The Mv is the result of both the effective visualflux and the equivalent radius. The equivalent radius is apparentlysmaller than the empirical radius due to a molecular covering process instars later than M3. The full range of optical red giant stars forms asequence from the brightest M early spectral types (S Car, M0(max),Mv approx = -3.2 mag) to the faintest M-latest spectral types(IK Tau, M10.5 min), Mv approx. = 16.5 mag). The typicalMiras and SR stars of M-medium and M-late spectral types are betweenthese two extremes. The sequence has a range of 20 mag on the visual(HR) diagram which extends from the red giant branch (RGB) passingbeyond the Mv of red dwarf stars as far as the point where itintercepts with the prolongation of the zero-age main sequence (ZAMS) inthe latest spectral type. Typical M10-stars at 200 pc has a V approx. =20 mag. M-latest stars at larger distances are unobservable stars in thevisual band. The distances of 134 variable stars are also given. Thedistances to 86 stars were determined by using a pure photometricmethod, while preliminary distances (less than 200 pc) for the remaining48 M-latest stars were determined by the spectral-photometric method.Since the local stellar density of M stars up to 100 pc rises at least7.5 times, it is possible to discuss that the long-standing problem ofdark matter in spiral galaxies could be resolved by these very dimmassive giant stars and by the molecular covered stars at the extremeend of the attenuating sequence. Furthermore, post M-latest stars may bethe only nonvisual stellar objects that can explain the enormousquantity of faint and point infrared sources found by IRAS. These weakobjects suggest the existence of an infrared Milky Way which is moredense than the optical one.
| The general catalogue of trigonometric [stellar] paralaxes
Not Available
| A large, complete, volume-limited sample of G-type dwarfs. I. Completion of Stroemgren UVBY photometry
Four-colour photometry of potential dwarf stars of types G0 to K2,selected from the Michigan Spectral Catalogues (Vol. 1-3), has beencarried out. The results are presented in a catalogue containing 4247uvby observations of 3900 stars, all south of δ = -26deg. Theoverall internal rms errors of one observation (transformed to thestandard system) of a program star in the interval 8.5 < V < 10.5are 0.0044, 0.0021, 0.0039, and 0.0059, respectively, in V, b-y, m_1_ ,and c_1_. The purpose of the catalogue, combined with earliercatalogues, is to allow selection of a large, complete, volume-limitedsample of G- and K-type dwarfs, investigate their metallicitydistribution, and compare it to predictions of various models ofgalactic chemical evolution. Future papers in this series will discussthese subjects.
| Short- and intermediate-period oxygen-rich Miras
Available IR photometry and the period-IR luminosity relationship areused to analyze a nearly complete sample of oxygen-rich Miras atGalactic latitudes with /b/ greater than 30 deg. In agreement withprevious kinematic studies, a marked difference is found in the spatialdistributions between the stars with periods less than and those withperiods greater than 300 d. For stars with periods in the range 300-400d, the exponential scale height from the Galactic plane is close to 240pc, the projected surface density is about 100/sq kpc, and the localspace density is about 210/cu kpc. The progenitors of the Miras withperiods greater than 300 d appear to be disk dwarfs with typicalmain-sequence masses of between 1.0 and 1.2 solar masses. The masses ofthe main-sequence progenitors of the short-period Miras are 1.1 solarmasses or less. The duration of the Mira phase for theintermediate-period stars is estimated to be about 20,000 yr, somewhatlonger than other recent estimates. Both short- and intermediate-periodoxygen-rich Miras characteristically lose mass at about 10 exp -7 solarmass/yr.
| A survey for infrared excesses among high galactic latitude SAO stars
This project involves extending the previous analysis of infraredexcesses among a volume-limited sample of 134 nearby A-K main-sequencestars to a magnitude-limited sample of stars, culled from the SAOCatalog, with excesses determined from the IRAS Point Source Catalogflux density ratios. This new sample includes 5706 B-M type stars, 379of which have infrared excesses. The objective involved use of astatistically complete survey of objects in a standard catalog in orderto assess the frequency with which different physical processes canaffect the infrared output of stars. These processes include, but arenot limited to, orbiting cold particle clouds and the onset of rapidmass loss. It is concluded that cold disks are consistent with theinfrared excesses found among A-G dwarfs and G-K giants in the sample.
| Hyades and Sirius supercluster members brighter than magnitude(V) 7.1. I - The first six hours of right ascension
This is the first of four papers listing the probable members of theHyades and Sirius superclusters among stars brighter than V = 7.1 mag.The star sample is contained in the Bright Star Catalogue and itsSupplement, augmented with a further supplement of 550 stars foundduring various observing programs over the past 40 years. Accurate,four-color and H-beta, or (RI), photometry is available for most of thesupercluster members. The criteria for membership are the comparisons ofthe proper motion, radial velocity, and luminosity obtained from thesupercluster parameters with the observed motions and the luminosityderived from the photometric parameters. New proper motions, based onall available catalogs, have been derived for the additional 550 starsdiscussed here, as well as for all supercluster members.
| Red variable stars. I - UBVRI photometry and photometric properties
In all phases of the light cycle of red variables stars, theirnear-infrared colors define a narrow sequence in the two color (V - R, R- I) diagram. This does not occur with other cool variable stars oftypes Ce, Se, and Ne. The position of a red variable on this sequence isvery sensitive to the Me spectral type. The colors are molecularabsorption indices, fundamentally of TiO, rather than indices of thecolor temperature. In general, the photometric magnitudes for a given Mestar result from surfaces of different stellar radius and depend on thepresence or absence of absorbing bands in the observed spectralcontinuum. This result is discussed in terms of amplitudes, radius,visual absolute magnitudes, and effective temperature, all of them freeof or affected by TiO. Finally, these results give more information onwhich to build a model whose radial structure would have a relativelyhigh stellar effective temperature and several cool covers of TiOmolecules.
| Variable stars in the General Catalogue of Trigonometric Parallaxes
Not Available
| The physical properties of the ZZ Ceti stars and their pulsations
Stromgren colors for the ZZ Ceti variables are used to fix the meanpositions of individual stars in the H-R diagram. The ZZ Ceti stars arefound to be normal white dwarfs occurring in the temperature range fromabout 10,500 K to 13,500 K on the DA cooling sequence. The onset ofvariability among DA white dwarfs is shown to be an evolutionary effectoccurring at the maximum of hydrogen capacity on the DA sequence.Time-resolved Stromgren photometry is used to examine the changes of theeffective temperature, the radius, and the effective surface gravitywith time during a pulsation to evaluate the relative contribution ofthese parameters to the total luminosity variation. The increase ineffective temperature during a pulsation is observed to be sufficient toaccount for the entire change in luminosity. Changes in the radius ofthe star and the effective gravity during a pulsation are shown to besmall. It is suggested that the partial ionization zones associated withthe high opacity provide the driving mechanism for the ZZ Ceti stars.
| Statistical analysis of the light curves of variable stars.
Not Available
| The classification of intrinsic variables. VII - The medium-amplitude red variables
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977ApJ...213..767E&db_key=AST
| Photoelectric photometry of late-type variable stars
We present 168 photoelectric (UBV) observations of 30 late-type variablestars of long period which were made systematically during 8 observingruns from 1972 December to 1973 September. The B-V and U-B color indicesobtained near maximum and minimum in V are plotted in the two-colordiagram.
| Revised Catalog of Spectra of Mira Variables of Types ME and Se
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJS...28..271K&db_key=AST
| Narrow-and broad-band photometry of red stars. VII. Luminosities and temperatures for halo-population red stars of high luminosity
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972ApJ...172..639E&db_key=AST
| A Catalogue of Spectra of Mira Variables of Types ME and Se
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966ApJS...13..333K&db_key=AST
| The long period variables
Abstract image available at:http://adsabs.harvard.edu/abs/1963MNRAS.125..367F
| The proper-motions of 315 red stars
Not Available
| Stars having peculiar spectra. Eleven new variable stars.
Not Available
|
הכנס מאמר חדש
לינקים קשורים
הכנס לינק חדש
משמש של הקבוצה הבאה
|
תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | צייר |
| התרוממות ימנית: | 04h46m09.55s |
| סירוב: | -49°14'45.0" |
| גודל גלוי: | 7.894 |
| מרחק: | 448.43 פארסק |
| תנועה נכונה: | 35.6 |
| תנועה נכונה: | 37.2 |
| B-T magnitude: | 9.913 |
| V-T magnitude: | 8.061 |
קטלוגים וכינוים:
|
