Home     Per cominciare     Sopravvivere Nell'Universo    
Inhabited Sky
    News@Sky     Astro Foto     La collezione     Forum     Blog New!     FAQ     Stampa     Login  

HD 21940


Contenuti

Immagini

Carica la tua immagine

DSS Images   Other Images


Articoli relazionati

Statistical Constraints for Astrometric Binaries with Nonlinear Motion
Useful constraints on the orbits and mass ratios of astrometric binariesin the Hipparcos catalog are derived from the measured proper motiondifferences of Hipparcos and Tycho-2 (Δμ), accelerations ofproper motions (μ˙), and second derivatives of proper motions(μ̈). It is shown how, in some cases, statistical bounds can beestimated for the masses of the secondary components. Two catalogs ofastrometric binaries are generated, one of binaries with significantproper motion differences and the other of binaries with significantaccelerations of their proper motions. Mathematical relations betweenthe astrometric observables Δμ, μ˙, and μ̈ andthe orbital elements are derived in the appendices. We find a remarkabledifference between the distribution of spectral types of stars withlarge accelerations but small proper motion differences and that ofstars with large proper motion differences but insignificantaccelerations. The spectral type distribution for the former sample ofbinaries is the same as the general distribution of all stars in theHipparcos catalog, whereas the latter sample is clearly dominated bysolar-type stars, with an obvious dearth of blue stars. We point outthat the latter set includes mostly binaries with long periods (longerthan about 6 yr).

Secondary standards for H-beta photometry in the Southern Hemisphere (second series).
Not Available

UBV (RI)c standard stars in the E- and F-regions and in the Magellanic Clouds - a revised catalogue.
Not Available

UBV(RI)c photometry of some standard sequences in the Harvard F regions and in the Magellanic Clouds
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1988MNRAS.231.1047M&db_key=AST

DDO Observations of Southern Stars
Not Available

Standard Stars for VRI Photometry with S25 Response Photocathodes
Not Available

Further observations of magnitude with a coarse grating
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1952MNRAS.112..665W&db_key=AST

Sottometti un nuovo articolo


Link relazionati

  • - Nessun link trovato -
Sottometti un nuovo link


Membro dei seguenti gruppi:


Osservazione e dati astrometrici

Costellazione:Idro
Ascensione retta:03h24m36.88s
Declinazione:-76°44'46.6"
Magnitudine apparente:6.801
Distanza:94.162 parsec
Moto proprio RA:-42.1
Moto proprio Dec:-67.9
B-T magnitude:7.05
V-T magnitude:6.822

Cataloghi e designazioni:
Nomi esatti   (Edit)
HD 1989HD 21940
TYCHO-2 2000TYC 9363-826-1
USNO-A2.0USNO-A2 0075-00565633
HIPHIP 15886

→ Richiesta di ulteriori cataloghi da VizieR