Contingut
Imatges
Carregar la teva Imatge
DSS Images Other Images
Articles Relacionats
Kinematics of gas and stars in the circumnuclear star-forming ring of NGC3351
We have measured gas and stellar velocity dispersions in fivecircumnuclear star-forming regions (CNSFRs) and the nucleus of thebarred spiral galaxy NGC3351. The stellar dispersions have been obtainedfrom high-resolution spectra of the CaII triplet (CaT) lines atλλ8494, 8542, 8662Å, while the gas velocitydispersions have been measured by Gaussian fits to the Hβλ4861Å line on high-dispersion spectra.The CNSFRs, with sizes of about 100 to 150pc in diameter, are seen to becomposed of several individual star clusters with sizes between 1.7 and4.9pc on a Hubble Space Telescope (HST) image. Using the stellarvelocity dispersions, we have derived dynamical masses for the entirestar-forming complexes and for the individual star clusters. Values ofthe stellar velocity dispersions are between 39 and 67kms-1.Dynamical masses for the whole CNSFRs are between 4.9 ×106 and 4.3 × 107Msolar andbetween 1.8 and 8.7 × 106Msolar for theindividual star clusters.Stellar and gas velocity dispersions are found to differ by about20kms-1 with the Hβ lines being narrower than both thestellar lines and the [OIII]λ5007Å lines. We have foundindications for the presence of two different kinematical components inthe ionized gas of the regions. The radial velocity curve showsdeviation from circular motions for the ionized hydrogen consistent withits infall towards the central regions of the galaxy at a velocity ofabout 25kms-1. To disentangle the origin of these twocomponents it will be necessary to map these regions with high spectraland spatial resolution and much better signal-to-noise ratio inparticular for the O2+ lines.
| 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.
| Evolved GK stars near the sun. I - The old disk population
A sample of nearly two thousand GK giants with intermediate band, (R,I),DDO and Geneva photometry has been assembled. Astrometric data is alsoavailable for most of the stars. The some 800 members of the old diskpopulation in the sample yield accurate luminosities (from two sources),reddening values and chemical abundances from calibrations of thephotometric parameters. Less than one percent of the objects arepeculiar in the sense that the flux distribution is abnormal. Thepeculiarity is signaled by strong CH (and Ba II) and weak CH. The CH+stars are all spectroscopic binaries, probably with white dwarfcompanions, whereas the CH- stars are not. A broad absorption band,centered near 3500 A, is found in the CH+ stars whereas the CH- objectshave a broad emission feature in the same region. The intensity of theseabsorptions and emissions are independent of the intensity of abnormalspectral features. Ten percent of the old disk sample have a heavyelement abundance from one and a half to three times the solar value.The distribution of the heavy element abundances is nearly a normal onewith a peak near solar abundance and ranges three times to one sixthsolar. The distribution of the (U, V) velocities is independent of theheavy element abundance and does not appear to be random. Ten percent ofthe old disk stars show a CN anomaly, equally divided between CN strongand CN weak. Several stars of individual astrometric or astrophysicalimportance are isolated.
| Large and kinematically unbiased samples of G- and K-type stars. VI - Evolved stars in the Moore-Paddock-Wayman sample
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990PASP..102..507E&db_key=AST
| Estimation of spectral classifications for bright southern stars with interesting Stromgren indices
This paper investigates the degree of success with which uvby photometrycan be applied to predict spectral classifications for 947 A, F, and Gstars brighter than an apparent magnitude of 8.3 and with four-colorindices indicating some kind of interesting, unusual, or peculiarspectrum. One or several possible spectral classifications are estimatedfor each star from photometry alone, double stars are distinguished, andthe estimates are compared with published classifications. The resultsshow that the framework provided by uvby photometry can be extended toinclude most G and K stars, reddened stars, peculiar stars, and certaintypes of double star.
| Radial Velocities, Spectral Types, and Luminosity Classes of 820 Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1950ApJ...112...48M&db_key=AST
|
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: | Taurus |
| Ascensió Recta: | 03h32m48.45s |
| Declinació: | -00°30'09.7" |
| Magnitud Aparent: | 8.485 |
| Distancia: | 258.398 parsecs |
| Moviment propi RA: | 3 |
| Moviment propi Dec: | 24.2 |
| B-T magnitude: | 9.604 |
| V-T magnitude: | 8.578 |
Catàlegs i designacions:
|
