Contingut
Imatges
Carregar la teva Imatge
DSS Images Other Images
Articles Relacionats
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
| Quasar Lyman Edge Regions in Polarized Light
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...450..501K&db_key=AST
| Placid stars and excited gas in NGC 4826
We present an investigation of the kinematics of the stars and theionized gas along the principal axes of the galaxy NGC 4826. This galaxyis known to contain two nested, counterrotating, gas disks of a few108 solar mass each, with the inner disk extending toapproximately 1 kpc and the outer disk extending beyond. The stellarkinematics along the major axis, extending across the transition regionbetween the two gas disks, show no hint of velocity reversal orincreased velocity dispersion. The stars always rotate in the same senseas the inner gas disk, and thus it is the outer disk which'counterrotates'. The projected circular velocities inferred from thestellar kinematics and from the H I disks agree to within approximately10 km/s, supporting other evidence that the stellar and gaseous disksare coplanar to approximately 7 deg. Using a detailed analysis of thestellar velocity distributions, we can limit the fraction ofcounterrotating stars in the outer disk to approximately less than or =0.05, or approximately less than or = 2 x 108 solar mass.This upper limit is comparable to the mass of detected counterrotatinggas. This low mass of counterrotating material, combined with thelow-velocity dispersion in the stellar disk, implies that NGC 4826cannot be the product of a retrograde merger of galaxies, unless theydiffered by at least an order of magnitude in mass. The velocities ofthe ionized gas along the major axis are in agreement with that of thestars for R less than 0.75 kpc. The subsequent transition towardapparent counterrotation of the ionized gas is spatially well resolved,extending over approximately 0.6 kpc in radius. The kinematics of thisregion are not symmetric with respect to the galaxy center. On thesoutheast side there is a significant region in which vproj(H II) much less than vcirc approximately 150 km/s, but sigma(H II) approximately 65 km/s. The kinematic asymmetries cannot beexplained with any stationary dynamical model, even is gas inflow orwarps were invoked. The gas in this transition region shows a diffusespatial structure, strong (N II) and (S II) emission, as well as thehigh-velocity dispersion. These data present us with the conundrum ofexplaining a galaxy in which a stellar disk, and two counterrotating H Idisks, at smaller and much larger radii, appear in equilibrium andnearly coplanar, yet in which the transition region between the gasdisks is not in steady state.
| 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.
| Observational Data for the Kinematics of the Local Universe - Part Two - Second Set of Radial Velocity Measurements
This paper is the second one in a series dedicated to the study of thekinematics of the local universe. It gives 361 new optical and radioredshifts measured at ESO, OHP and Nancay Observatories.
| A library of near-IR stellar spectra from 1.328 to 2.5 microns
We present a library of 56 stellar spectra from 1.428 to 2.5 microns,sampling the Hertzsprung-Russell diagram in luminosity class andeffective temperature. Relative fluxes defining the stellar energydistributions throughout the H and K atmospheric windows, an infraredcolor temperature used to set a continuum for equivalent widthmeasurements, and relations between various spectral signatures, colortemperatures and gravity are determined. H2O is the dominant absorber inthe latest M giant stars. Its absorption is measured in both wings ofthe signature around 1.9 micron and a combined effect of H2O and H(-)opacity is measured shortward of 1.6 micron. The CO equivalent widthlongward of 2.29 microns increases with decreasing gravity andtemperature. CO and the OH radical are responsible for numerousabsorption bands below 1.8 micron.
| The rotational break for G giants
New high-resolution spectroscopic observations have been obtained for 73G giants. Fourier analysis of their spectral lines yields rotationvelocities and macroturbulence dispersions. Combined with data from anearlier study, total of 86 analyses of luminosity class III giants isnow available. The existence of a rotational discontinuity forluminosity class III giants is confirmed, but it is found to be near G0III rather than G5 III, as indicated in the earlier work. Evidence forrotation being a single-valued function of spectral type isstrengthened. The observations are interpreted in terms of adynamo-generated magnetic brake and a 'rotostat' phenomenon.
| Polarimetric Observations of Nearby Stars in the Directions of the Galactic Poles and the Galactic Plane
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968ApJ...151..907A&db_key=AST
| MK Spectral Types for 185 Bright Stars
Not Available
|
Enviar un nou article
Enllaços Relacionats
- - No s'ha trobat enllaços -
Enviar un nou enllaç
Membre dels grups següents:
|
Dades d'Observació i Astrometria
| Constel·lació: | Canes Venatici |
| Ascensió Recta: | 13h42m28.80s |
| Declinació: | +41°40'27.0" |
| Magnitud Aparent: | 6.3 |
| Distancia: | 289.017 parsecs |
| Moviment propi RA: | -85.9 |
| Moviment propi Dec: | 12.9 |
| B-T magnitude: | 7.402 |
| V-T magnitude: | 6.388 |
Catàlegs i designacions:
|
INHABITED SKY
