Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
Rotational velocities of A-type stars. III. Velocity distributions
Aims.A sample of v sin i of B9 to F2-type main sequence single stars hasbeen built from highly homogeneous {v sin i} parameters determined for alarge sample cleansed of objects presenting the Am and Ap phenomenon aswell as of all known binaries. The aim is to study the distributions ofrotational velocities in the mass range of A-type stars for normalsingle objects. Methods: .Robust statistical methods are used torectify the {v sin i} distributions for the projection effect and theerror distribution. The equatorial velocity distributions are obtainedfor about 1100 stars divided in six groups defined by the spectral type,under the assumption of randomly orientated rotational axes.Results: .We show that late B and early A-type main-sequence stars havegenuine bimodal distributions of true equatorial rotational velocitiesprobably due to angular momentum loss and redistribution that the starunderwent before reaching the main sequence. A striking lack of slowrotators is noticed among intermediate and late A-type stars.Full Table [see full text] is 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/cgi-bin/qcat?J/A+A/463/671 Appendices areonly available in electronic form at http://www.aanda.org
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| 3D mapping of the dense interstellar gas around the Local Bubble
We present intermediate results from a long-term program of mapping theneutral absorption characteristics of the local interstellar medium,motivated by the availability of accurate and consistent parallaxes fromthe Hipparcos satellite. Equivalent widths of the interstellar NaID-line doublet at 5890 Å are presented for the lines-of-sighttowards some 311 new target stars lying within ~ 350 pc of the Sun.Using these data, together with NaI absorption measurements towards afurther ~ 240 nearby targets published in the literature (for many ofthem, in the directions of molecular clouds), and the ~ 450lines-of-sight already presented by (Sfeir et al. \cite{sfeir99}), weshow 3D absorption maps of the local distribution of neutral gas towards1005 sight-lines with Hipparcos distances as viewed from a variety ofdifferent galactic projections.The data are synthesized by means of two complementary methods, (i) bymapping of iso-equivalent width contours, and (ii) by densitydistribution calculation from the inversion of column-densities, amethod devised by Vergely et al. (\cite{vergely01}). Our present dataconfirms the view that the local cavity is deficient in cold and neutralinterstellar gas. The closest dense and cold gas ``wall'', in the firstquadrant, is at ~ 55-60 pc. There are a few isolated clouds at closerdistance, if the detected absorption is not produced by circumstellarmaterial.The maps reveal narrow or wide ``interstellar tunnels'' which connectthe Local Bubble to surrounding cavities, as predicted by the model ofCox & Smith (1974). In particular, one of these tunnels, defined bystars at 300 to 600 pc from the Sun showing negligible sodiumabsorption, connects the well known CMa void (Gry et al. \cite{gry85}),which is part of the Local Bubble, with the supershell GSH 238+00+09(Heiles \cite{heiles98}). High latitude lines-of-sight with the smallestabsorption are found in two ``chimneys'', whose directions areperpendicular to the Gould belt plane. The maps show that the LocalBubble is ``squeezed'' by surrounding shells in a complicated patternand suggest that its pressure is smaller than in those expandingregions.We discuss the locations of several HI and molecular clouds. Usingcomparisons between NaI and HI or CO velocities, in some cases we areable to improve the constraints on their distances. According to thevelocity criteria, MBM 33-37, MBM 16-18, UT 3-7, and MBM 54-55 arecloser than ~ 100 pc, and MBM 40 is closer than 80 pc. Dense HI cloudsare seen at less than 90 pc and 85 pc in the directions of the MBM 12and MBM 41-43 clouds respectively, but the molecular clouds themselvesmay be far beyond. The above closest molecular clouds are located at theneutral boundary of the Bubble. Only one translucent cloud, G192-67, isclearly embedded within the LB and well isolated.These maps of the distribution of local neutral interstellar NaI gas arealso briefly compared with the distribution of both interstellar dustand neutral HI gas within 300 pc.Tables 1 and 2 are only 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/411/447
| Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i
This work is the second part of the set of measurements of v sin i forA-type stars, begun by Royer et al. (\cite{Ror_02a}). Spectra of 249 B8to F2-type stars brighter than V=7 have been collected at Observatoirede Haute-Provence (OHP). Fourier transforms of several line profiles inthe range 4200-4600 Å are used to derive v sin i from thefrequency of the first zero. Statistical analysis of the sampleindicates that measurement error mainly depends on v sin i and thisrelative error of the rotational velocity is found to be about 5% onaverage. The systematic shift with respect to standard values fromSlettebak et al. (\cite{Slk_75}), previously found in the first paper,is here confirmed. Comparisons with data from the literature agree withour findings: v sin i values from Slettebak et al. are underestimatedand the relation between both scales follows a linear law ensuremath vsin inew = 1.03 v sin iold+7.7. Finally, thesedata are combined with those from the previous paper (Royer et al.\cite{Ror_02a}), together with the catalogue of Abt & Morrell(\cite{AbtMol95}). The resulting sample includes some 2150 stars withhomogenized rotational velocities. Based on observations made atObservatoire de Haute Provence (CNRS), France. Tables \ref{results} and\ref{merging} are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/897
| Rotational velocities of A-type stars. I. Measurement of v sin i in the southern hemisphere
Within the scope of a Key Programme determining fundamental parametersof stars observed by HIPPARCOS, spectra of 525 B8 to F2-type starsbrighter than V=8 have been collected at ESO. Fourier transforms ofseveral line profiles in the range 4200-4500 Å are used to derivev sin i from the frequency of the first zero. Statistical analysis ofthe sample indicates that measurement error is a function of v sin i andthis relative error of the rotational velocity is found to be about 6%on average. The results obtained are compared with data from theliterature. There is a systematic shift from standard values from\citet{Slk_75}, which are 10 to 12% lower than our findings. Comparisonswith other independent v sin i values tend to prove that those fromSlettebak et al. are underestimated. This effect is attributed to thepresence of binaries in the standard sample of Slettebak et al., and tothe model atmosphere they used. Based on observations made at theEuropean Southern Observatory (ESO), La Silla, Chile, in the frameworkof the Key Programme 5-004-43K. Table 4 is only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5)or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/381/105
| Radial velocities of HIPPARCOS southern B8-F2 type stars
Radial velocities have been determined for a sample of B8-F2 type starsobserved by the Hipparcos satellite. Observations were obtained withinthe framework of an ESO key-program. Radial velocities have beenmeasured using a cross-correlation method, the templates being a grid ofsynthetic spectra. The obtained precision depends on effectivetemperature and projected rotational velocity of the star as well as ona possible asymmetry of the correlation peak generally due to secondarycomponents. New spectroscopic binaries have been detected from theseasymmetries and the variability of the measured radial velocity.Simulations of binary and triple systems have been performed. Forbinaries our results have been compared with Hipparcos binary data.Adding the variable radial velocities, the minimum binary fraction hasbeen found 60% for physical systems. Radial velocities have beendetermined for 581 B8-F2 stars, 159 being new. Taking into accountpublished radial velocities, 39% south A-type stars with V magnitudelower than 7.5 have a radial velocity. Based on observations obtained atthe European Southern Observatory (ESO, La Silla, Chile) and on datafrom the ESA Hipparcos astrometry satellite.}\fnmsep \thanks{Tables 7, 8and 9 are only available in electronic form at the CDS via anonymous ftpto cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| UVBY CCD photometry of the upper main sequence in Omega Centauri
CCD frames on the uvby system of a field in Omega Centauri are obtainedand analyzed in order to constrain the intrinsic dispersion of heavyelements among its unevolved stars. Results from direct measurements onthe metallicity using m1 and from indirect measures using the colorspread in (b-y) near the turnoff imply an intrinsic dispersion in Fe/Hof about 1 dex, similar to the results of spectroscopic analysis of theevolved stars. The color spread near the turnoff is consistent withlittle spread in age, though the constraint is weak. The variable bluestraggler E39 is recovered showing an additional blue-stragglercandidate. The variation in c1 as a function of magnitude for probableupper-main-sequence members suggests that previous evolutionarycorrections for metal-poor stars were overestimated.
| Early type high-velocity stars in the solar neighborhood. IV - Four-color and H-beta photometry
Results are presented from photometric obaservations in the Stromgrenuvby four-color and H-beta systems of early-type high-velocity stars inthe solar neighborhood. Several types of photometrically peculiar starsare selected on the basis of their Stromgren indices and areprovisionally identified as peculiar A stars, field horizontal-branchstars, metal-poor stars near the Population II and old-disk turnoffs,metal-poor blue stragglers, or metallic-line A stars. Numerousphotometrically normal stars were also found.
| Empirical temperature calibrations for early-type stars
Three temperature calibrations of suitable photometric quantities havebeen derived for O and B stars. A sample of 120 stars with reliableT(eff.) determinations has been used for establishing each calibration.The different calibrations have been critically discussed and compared.Temperature determinations for 1009 program stars have been obtainedwith an accuracy of the order of 10 percent.
| Early-type high-velocity stars in the solar neighborhood. III - Radial velocities, rotation indices, and line-strength indices for southern candidates
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983AJ.....88.1349S&db_key=AST
| Spectral Classification and DDO Photometry of a Southern Group of Stars with Common Motions - Part One
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1982PASP...94..304L&db_key=AST
| Early-type high-velocity stars in the solar neighborhood. II Photometry for 78 candidates
H-beta and four-color photometry are presented for 78 early-type,high-velocity star candidates consisting of: (1) 74 candidates listed ina previous paper; and (2) four candidates identified by Eggen (1970).All of the sample appears to be near the main sequence, with theexception of five of the AO-type stars that are probably on the fieldPopulation II horizontal branch. Almost one-third of the main-sequence Astars and nearly all of the F stars are seen as true high-velocityobjects, and several of the high-velocity F stars appear to have solarmetal abundances. The existence of young, metal-rich, high-velocitystars is supported by the data, and it is concluded that this populationmay contribute one A star to every thousand stars in the solarneighborhood.
| Early-type high-velocity stars in the solar neighborhood. I - List of candidates
Suspected nearby high-velocity stars of spectral types B and A areidentified by their proper motions, which are generally too small forthe stars to have been included in previous catalogs of high-velocitystars. The same selection process is then extended to spectral type Fstars, in order to both provide a companion sample and investigatewhether the hypothetical high-velocity, metal-rich population continuesto later spectral types. Of the presented list of 371 stars withconfirmed proper motions, 168 are of A and B spectral types. Photometricand spectroscopic observations of these stars are required to eliminatethose with misclassified spectra and convert proper motions into spacevelocities. The identification of type of stars is important forunderstanding apparent exceptions to the correlation between stellarages, metal abundances, and kinematic properties.
| Polarization measurements of 313 nearby stars
The linear polarization of 313 low galactic latitude stars has beenmeasured. With few exceptions all program stars have a spectral typelater than B9 and are within 600 parsec of the sun. 181 stars aresituated at the southern sky and 132 at the northern sky.
| Radial Velocities and three-colour photometry of 52 stars with large proper motions
Abstract image available at:http://adsabs.harvard.edu/abs/1965MNRAS.129...63P
| Stars, Parallax of : Stellar parallaxes determined photogrphically at the Cape Observatory (seventeenth list)
Not Available
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
| Созвездие: | Паруса |
| Прямое восхождение: | 10h14m50.21s |
| Склонение: | -41°43'33.9" |
| Видимая звёздная величина: | 6.544 |
| Расстояние: | 80.841 парсек |
| Собственное движение RA: | -114.3 |
| Собственное движение Dec: | 32.4 |
| B-T magnitude: | 6.736 |
| V-T magnitude: | 6.56 |
Каталоги и обозначения:
|
