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J/A+AS/128/29      X-ray/optical observations of A8-G2V stars     (Piters+ 1998)
X-ray/optical observations of stars with shallow convection zones (A8-G2 V)
       Piters A.J.M., Van Paradijs J., Schmitt J.H.M.M.
      <Astron. Astrophys. Suppl. Ser. 128, 29 (1998)>
      =1998A&AS..128...29P      (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Photometry, VBLUW ; Effective temperatures ;
              X-ray sources
Keywords: stars: activity; fundamental parameters - X-rays: stars


Description:
    Table 1 lists the sample of 173 stars observed for this study. They
    are selected from the Bright Star Catalogue (Cat. V/50), with the
    following selection criteria:
    - Spectral type between A8 and G2; no spectral peculiarities noted;
       not double in spectral type classification (e.g., HR 32 with
       spectral type F2V+F6V is excluded);
    - Luminosity class V;
    - Right ascension between 0h and 2h, or between 14h and 24 h,
       declination south of +10 degrees (defining the region on the sky
       visible during the appointed observation times);
    - Binaries for which both components occurred in the BSC are excluded,
       if the separation is less than 10". Not listed are five stars for
       which no (Walraven photometric and ROSAT X-ray) data are available.
       These are HR 591, HR 5542, HR 6593, HR 8245 and HR 8735.
    Table 2 lists the Walraven photometric (VBLUW) data for all but four
    stars from Table 1. Also listed in Table 2 are the effective
    temperature, surface gravity and the reddening, as derived from
    comparison with theoretical colours.
    Table 5 lists the ROSAT All Sky Survey data for all but 11 stars from
    Table 1.
    For a description of the Walraven photometric system, see e.g. GCPD/11

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1            23      173   Sample stars
table2           123      169   Walraven photometry data
table5           110      162   ROSAT X-ray data


Byte-by-byte Description of file: table1

   Bytes Format Units   Label     Explanations

   1-  4  I4    ---     HR        HR (Cat. V/50) number
       6  A1    ---     Note      [AB] See Note (1)
   8- 12  A5    ---     Type      Spectral Type (2)
  14- 18  F5.2  mag     Vmag      Apparent visual Johnson V magnitude (2)
  20- 23  F4.2  mag     B-V       Johnson's B-V colour (2)

Note (1): A: No Walraven data available
          B: No ROSAT data available
Note (2): Data from HR (Cat. V/50) catalog



Byte-by-byte Description of file: table2

   Bytes Format Units   Label     Explanations

   1-  4  I4    ---     HR        HR number (as in table1)
       6  A1    ---     Note      [*] See Note (1)
   8- 15  F8.5  mag     VWmag     visual (Walraven) magnitude V
  17- 23  F7.5  mag     e_VWmag   standard deviation in VWmag
  25- 31  F7.5  mag     V-B       Walraven colour V-B
  33- 39  F7.5  mag     e_V-B     Standard deviation in V-B
  41- 47  F7.5  mag     B-U       Walraven colour B-U
  49- 55  F7.5  mag     e_B-U     Standard deviation in B-U
  57- 63  F7.5  mag     U-W       Walraven colour U-W
  65- 71  F7.5  mag     e_U-W     Standard deviation in U-W
  73- 79  F7.5  mag     B-L       Walraven colour B-L
  81- 87  F7.5  mag     e_B-L     Standard deviation in B-L
  89- 90  I2    ---     o_B-L     Number of observations
  92- 95  I4    K       Teff      Effective temperature
  97- 99  I3    K       e_Teff    ? Uncertainty in Teff (2)
 101-104  F4.2  [cm/s2] logg      Logarithm of surface gravity
 106-109  F4.2  [cm/s2] e_logg    ? Uncertainty in logg (2)
 111-116  F6.4  mag     E(V-B)    The reddening E(V-B)
 118-123  F6.4  mag     e_E(V-B)  ? Uncertainty in E_V-B (2)

Note (1): *: Probably variable: standard deviation of the brightness or one of
              the Walraven colours is more than 4 times as large as the average
              standard deviation.
Note (2): If the uncertainties are not given, no consistent stellar parameters
           could be found by the method applied here (minimum chi-square
           larger than 10).


Byte-by-byte Description of file: table5

   Bytes Format    Units      Label     Explanations

   1-  4  I4       ---        HR        HR number (as in table1)
       6  A1       ---        Note      [U] See Note (1)
   8- 11  F4.2     s-1        Count     X-ray count rate
  13- 16  F4.2     s-1        E_Count   ? Positive uncertainty in Count
  18- 21  F4.2     s-1        e_Count   ? Negative uncertainty in Count
  23- 26  F4.2     ---        XHR       ? Hardness ratio
  28- 31  F4.2     ---        E_XHR     ? Positive uncertainty in XHR
  33- 36  F4.2     ---        e_XHR     ? Negative uncertainty in XHR
  38- 42  F5.2    [10+7cm2/J] logCx     Log of energy-conversion factor (2)
  44- 47  F4.2    [10+7cm2/J] E_logCx   ? Positive uncertainty in logCx
  49- 52  F4.2    [10+7cm2/J] e_logCx   ? Negative uncertainty in logCx
  54- 58  F5.2     [cm-2]     lognH     Logarithm of hydrogen column density
  60- 63  F4.2     [cm-2]     e_lognH   Uncertainty in lognH
  65- 69  F5.2     ---        logRx     Log of Normalized X-ray flux density (3)
  71- 74  F4.2     ---        E_logRx   ? Positive uncertainty in logRx
  76- 79  F4.2     ---        e_logRx   ? Negative uncertainty in logRx
  81- 84  F4.2     ---        logFx     Log of X-ray surface flux density (3)
  86- 89  F4.2     ---        E_logFx   ? Positive uncertainty in logFx
  91- 94  F4.2     ---        e_logFx   ? Negative uncertainty in logFx
  96-100  F5.2     ---        logLx     Logarithmic X-ray luminosity (3)
 102-105  F4.2     ---        E_logLx   ? Positive uncertainty in logLx
 107-110  F4.2     ---        e_logLx   ? Negative uncertainty in logLx

Note (1): U: upper limit values for Count, logRx, logFx, and logLx;
          hardness ratio h and the uncertainties (E_h, e_h, E_logRx, e_logRx,
          E_logFx, e_logFx, E_logLx, and e_logLx-) are not given (left blank).
Note (2): The unit of the energy-conversion factor CX is: cm^2/ergs, so that
           fX = rs / CX is the flux density in ergs/(sec.cm^2) received at
           the detector.
Note (3): log Rx = log fX + 0.1(VJ + BC) + 4.574 (BC: bolometric correction)
          log Fx = log Rx + 4logTeff - 4.246
          log Lx = log Fx + 2log(R*/R☉) + 22.784


Acknowledgements: Ankie Piters 

(End) Ankie Piters [Astron. Inst., Amsterdam], Patricia Bauer [CDS]  09-Sep-1997