Home     Getting Started     To Survive in the Universe    
Inhabited Sky
    News@Sky     Astro Photo     The Collection     Forum     Blog New!     FAQ     Press     Login  

HD 171993


Contents

Images

Upload your image

DSS Images   Other Images


Related articles

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).

Mesures de vitesses radiales. VIII. Accompagnement AU sol DU programme d'observation DU satellite HIPPARCOS
We publish 1879 radial velocities of stars distributed in 105 fields of4^{\circ} \times 4^{\circ}. We continue the PPO series \cite[(Fehrenbachet al. 1987;]{Feh87} \cite[Duflot et al. 1990, 1992 and 1995),]{Du90}using the Fehrenbach objective prism method. Table 1 only available inelectronic form at CDS via to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html

Catalogue of proper motions in the declination of stars of the Moscow zenith zone.
Not Available

Submit a new article


Related links

  • - No Links Found -
Submit a new link


Member of following groups:


Observation and Astrometry data

Constellation:Draco
Right ascension:18h34m32.69s
Declination:+55°56'00.4"
Apparent magnitude:7.673
Distance:271.739 parsecs
Proper motion RA:-2.3
Proper motion Dec:-78.6
B-T magnitude:7.961
V-T magnitude:7.697

Catalogs and designations:
Proper Names   (Edit)
HD 1989HD 171993
TYCHO-2 2000TYC 3909-1165-1
USNO-A2.0USNO-A2 1425-09202942
HIPHIP 91065

→ Request more catalogs and designations from VizieR