Access to Astronomical Catalogues

J/PAZh/34/21       New spectral types for Tycho2 stars        (Tsvetkov+, 2008)
Inaccuracies in the spectral classification of stars from the Tycho-2 Spectral
Type Catalogue.
    Tsvetkov A.S., Popov A.V., Smirnov A.A.
   <Pis'ma Astron. Zh. 34, 21 (2008)>
   =2008PAZh...34...21T
   =2008AstL...34...17T
ADC_Keywords: Stars, nearby ; Spectral types ; MK spectral classification;
              Parallaxes, spectroscopic; Parallaxes, trigonometric ;
              Magnitudes, absolute
Keywords: stars - properties - classification - fundamental astronomy -
          astrometry - spectral classification - Tycho-2, Hipparcos

Abstract:
    We compare the spectroscopic and trigonometric parallaxes of common
    stars from the Tycho-2 Spectral Type and Hipparcos Catalogues. This
    comparison has revealed that the distance estimations for the
    overwhelming majority of stars by both methods yield very similar
    results. However, there is a small fraction of stars for which the
    distance estimates differences.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        50       61   Tabulated B-V color indices and absolute magnitudes
                             M for stars of various spectra and of luminosity
                             classes I, III and V
table2.dat        57      164   Stars with |δlogr|>1, their corrected
                             spectral types, and the logarithms of their
                             distances obtained by the spectroscopic
                             parallax method


See also:
      I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
    III/231 : The Tycho-2 Spectral Type Catalog (Wright+, 2003)


Byte-by-byte Description of file: table1.dat

   Bytes Format Units   Label     Explanations

   1-  2  A2    ---     SpClass   Spectral class
   5- 10  F6.3  mag     MAG-1     Absolute magnitude for Luminosity class I
  13- 18  F6.3  mag     (B-V)1    B-V index for Luminosity class I
  21- 26  F6.3  mag     MAG-3     Absolute magnitude for Luminosity class III
  29- 34  F6.3  mag     (B-V)3    B-V index for Luminosity class III
  37- 42  F6.3  mag     MAG-5     Absolute magnitude for Luminosity class V
  45- 50  F6.3  mag     (B-V)5    B-V index for Luminosity class V


Byte-by-byte Description of file: table2.dat

   Bytes Format Units   Label     Explanations

   1-  6  I6    ---     HIP       HIP (Cat. I/239) number
   8- 11  F4.2  [pc]    logRt     Logarithm of the distance derived from the
                                   trigonometric parallax
  13- 17  F5.2  [pc]    logRs     Logarithm of the distance derived from the
                                   spectroscopic parallax
  19- 23  F5.2  mag     BT-VT     B-V colour index from the Tycho-2 Spectral
                                   Types Catalogue (Cat. III/231)
  25- 29  F5.2  mag     VTmag     Apparent magnitude from the Tycho-2 Spectral
                                   Type Catalogue (Cat. III/231)
  31- 36  A6    ---     SpType    Spectral type from the Tycho-2 Spectral Type
                                   Catalogue (Cat. III/231)
      38  A1    ---     Type      [VHDMCNB] Star type (1)
  40- 49  A10   ---     SpType1   New (presumed) spectral type
  51- 52  A2    ---    n_SpType1  [sSlL ] Note on SpType1 (2)
  54- 57  F4.2  [pc]    logR1     ? Logarithm of the distance calculated from
                                     SpType1

Note (1): Star type as follows:
      V = variable star
      H = high-proper-motion star
      D = double star
      M = multiple star
      C = star observed against the background of a cluster
      N = carbon star
      B = star erroneously identified with Barnard's star
Note (2): Note on new spectral type as follows:
      S = spectral type and luminosity class from the SIMBAD database were used
      s = only the spectral type from the SIMBAD data base was used
          (the luminosity class is unavailable or ignored)
      L = luminosity class III was assigned
      l = luminosity class V was assigned
     sL = combination of the s and L flags

(End)            Veta Avedisova [INASAN],  Patricia Vannier [CDS]    09-Apr-2008