Principal     Comenzar     To Survive in the Universe    
Inhabited Sky
    News@Sky     Astrofotografía     La Colección     Foro     Blog New!     FAQ     Prensa     Login  

HD 19409


Contenidos

Imágenes

Subir su imagen

DSS Images   Other Images


Artículos relacionados

Revised Stellar Temperatures for Magellanic Cloud O Supergiants from Far Ultraviolet Spectroscopic Explorer and Very Large Telescope UV-Visual Echelle Spectrograph Spectroscopy
We have undertaken quantitative analysis of four LMC and SMC O4-9.7extreme supergiants using far-ultraviolet FUSE, ultraviolet IUE/HubbleSpace Telescope, and optical Very Large Telescope UV-Visual EchelleSpectrograph spectroscopy. Extended, non-LTE model atmospheres thatallow for the consistent treatment of line blanketing, developed byHillier & Miller, are used to analyze wind and photosphericsspectral features simultaneously. Using Hα to constrain mass-lossrates, He I-He II photospheric lines reveal stellar temperatures thatare systematically (5-7.5 kK) and substantially (15%-20%) lower thanpreviously derived from unblanketed, plane-parallel, non-LTEphotospheric studies. We have confidence in these revisions sincederived temperatures generally yield consistent fits across the entire912-7000 Å observed spectral range. In particular, we are able toresolve the UV-optical temperature discrepancy identified for AzV 232(O7 Iaf+) in the SMC by Fullerton and coworkers. Thetemperature and abundance sensitivity of far-ultraviolet, UV, andoptical lines are discussed. ``Of'' classification criteria are directlylinked to (strong) nitrogen enrichment (via N III λ4097) and(weak) carbon depletion (via C III λλ4647-4651), providingevidence for mixing of unprocessed and CNO-processed material at theirstellar surfaces. Oxygen abundances are more difficult to constrain,except via O II lines in the O9.7 supergiant, for which it is also foundto be somewhat depleted. Unfortunately, He/H is very difficult todetermine in individual O supergiants because of uncertainties inmicroturbulence and the atmospheric scale height. The effect of windclumping is also investigated, for which P V λλ1118-1128potentially provides a useful diagnostic in O star winds, unlessphosphorus can be independently demonstrated to be underabundantrelative to other heavy elements. Revised stellar properties affectexisting calibrations of (1) Lyman continuum photons-a factor of 2 lowerfor the O4 supergiant-and (2) kinetic energy released into the ISM by Osupergiants. Our results also have importance for the calibration of thewind momentum-luminosity relationship for OB stars, particularly sincethe stars studied here are among the visually brightest OB stars inexternal galaxies. Based on observations made with the NASA-CNES-CSA FarUltraviolet Spectroscopic Explorer. FUSE is operated for NASA by JohnsHopkins University under NASA contract NAS 5-32985. Also based in parton observations collected at the European Southern Observatory VeryLarge Telescopes in programs 65.H-0705 and 67.D-0238, plus archival dataobtained with the NASA-ESA Hubble Space Telescope and NASA-ESA-PPARCInternational Ultraviolet Explorer.

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. V - Evolved stars in the selected areas at + 15-deg declination
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990PASP..102..242E&db_key=AST

Photoelectric radial velocities. IV. 528 7 to 10 mag stars in the +15degree selected areas.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971MNRAS.155....1G&db_key=AST

Enviar un nuevo artículo


Enlaces relacionados

  • - No se han encontrado enlaces -
En viar un nuevo enlace


Miembro de los siguientes grupos:


Datos observacionales y astrométricos

Constelación:Carnero
Ascensión Recta:03h07m50.72s
Declinación:+16°04'23.6"
Magnitud Aparente:9.404
Movimiento Propio en Ascensión Recta:0.7
Movimiento Propio en Declinación:-22.1
B-T magnitude:10.936
V-T magnitude:9.531

Catálogos y designaciones:
Nombres Propios   (Edit)
HD 1989HD 19409
TYCHO-2 2000TYC 1225-370-1
USNO-A2.0USNO-A2 1050-00834404
HIPHIP 14550

→ Solicitar más catálogos y designaciones a VizieR