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J/AN/319/201  Alpha Per cluster low-mass members. I.   (Prosser+, 1998)
Identification of new low-mass members of the alpha Persei open cluster
by ROSAT. I.
       Prosser C.F., Randich S
      <Astron. Nachrichten 319, 201 (1998)>
      =1998AN....319..201P
ADC_Keywords: Clusters, open ; Photometry  ; X-ray sources ; Spectroscopy

Keywords: open clusters and associations: individual (alpha Per = Melotte 20) -
          stars: late-type - stars: coronae - stars: activity - X-rays: stars

Abstract:
    Following the work of Randich et al. (1996A&A...305..785R) involving a
    ROSAT raster scan survey of the α Persei open cluster, we
    present here the results of a photometric/spectroscopic program
    examining the possible optical counterparts to a group of 73 X-ray
    sources in the raster survey which were not matched to catalogued
    stars. Of the 73 sources investigated, ∼40 have an optical counterpart
    with photometry acceptable for cluster membership and ∼20 of these
    also have radial velocities consistent with membership. We discuss the
    X-ray properties of these potential new members and why they may not
    have been identified in earlier membership surveys of this cluster.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        55       73   Raster APX X-ray source list
table2.dat       106       89   Optical counterparts
notes.dat         80      102   Individual notes on finding charts (Appendix A)


See also:
       I/68 : Positions and Proper Motions in alpha Per cluster (Fresneau, 1980)
 J/AN/319/315 : Alpha Per cluster low-mass members. II. (Prosser+, 1998)


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

   Bytes Format Units   Label     Explanations

   1-  2  I2    ---     APX       [1/73] APX number
   4-  5  I2    h       RAh       Right ascension (J2000)
   7-  8  I2    min     RAm       Right ascension (J2000)
  10- 13  F4.1  s       RAs       Right ascension (J2000)
      15  A1    ---     DE-       Declination sign (J2000)
  16- 17  I2    deg     DEd       Declination (J2000)
  19- 20  I2    arcmin  DEm       Declination (J2000)
  22- 23  I2    arcsec  DEs       Declination (J2000)
  25- 29  F5.1  ---     MLh       Hardband Maximum Likelihood value
  31- 35  I5    s       ExpTime   Effective exposure time
  37- 42  F6.4  s-1    CountRate  Count rate
  44- 49  F6.4  s-1  e_CountRate  rms uncertainty on CountRate
      51  A1    ---     l_HR      Limit flag on HR
  52- 55  F4.1  ---     HR        Hardness ratio (1)

Note (1): HR=(H-S)/(H+S), where H and S are the count rates from the hard
           (0.4-2keV) and soft (0.1-0.4keV) bands respectively


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

   Bytes Format Units      Label     Explanations

   1-  2  I2    ---        APX       [1/73] APX number
   4- 10  A7    ---        Star      Star name (1)
      11  A1    ---        n_Star    [ab] Note detailed in notes.dat (2)
  12- 13  I2    h          RAh       Right ascension (J2000)
  15- 16  I2    min        RAm       Right ascension (J2000)
  18- 21  F4.1  s          RAs       Right ascension (J2000)
      23  A1    ---        DE-       Declination sign (J2000)
  24- 25  I2    deg        DEd       Declination (J2000)
  27- 28  I2    arcmin     DEm       Declination (J2000)
  30- 31  I2    arcsec     DEs       Declination (J2000)
  33- 37  F5.2  mag        Vmag      V magnitude
  39- 42  F4.2  mag        B-V       ? B-V colour index
      43  A1    ---        u_B-V     Uncertainty flag on B-V
  45- 48  F4.2  mag        V-Ik      ? (V-I)K colour index
      50  I1    ---        o_Vmag    ? Number of observation in V band
      51  I1    ---        o_Bmag    ? Number of observation in B band
      52  I1    ---        o_Imag    ? Number of observation in I band
  54- 57  F4.2  mag        B-V0      ? (B-V)0 colour index
  59- 63  F5.2  [solLum]   log(LX)   ? X-ray luminosity
  65- 69  F5.2  [solLum]  log(Lbol)  ? Bolometric luminosity
  71- 75  F5.2  ---    log(LX/Lbol)  ? X-ray to bolometric luminosity ratio
  78- 79  A2    ---        HaMemb    [YN ?] Hα member flag
      81  A1    ---        Halpha    [YN] Hα emission flag
  84- 86  F3.1  0.1nm      EWHa      ? Hα equivalent width
  88- 90  I3    km/s       RV1       ? Radial velocity for brighter stars,
                                        based on Hα observations
  92- 94  I3    km/s       RV2       ? Radial velocity for other stars,
                                        based on echelle observations
      97  A1    ---        l_vsini   Limit flag on vsini
  98- 99  I2    km/s       vsini     ? Rotational velocity for brighter stars,
                                        based on echelle observations
     100  A1    ---        u_vsini   Uncertainty flag on vsini
 102-103  A2    ---        MemRV     [YN ?] Membership from radial velocity
 105-106  A2    ---        Mem       [YN ?] Final membership

Note (1): APNNN: Cl*  Melotte 20 AP NNN in Simbad
          APXNN: APX NN in Simbad
         APXNNA: APX NNA in Simbad
        HE NNNN: Cl Melotte 20 NNNN in Simbad
Note (2): a: galaxy
          b: SB1 (see note in appena.dat file)


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

   Bytes Format Units   Label     Explanations

   1-  3  A3    ---     ---       [APX]
   4-  5  I2    ---     APX       APX Number
       6  A1    ---     m_APX     Multiplicity index
   8- 80  A73   ---     Note      Text of the note


History: Prepared via OCR at CDS.

(End)                           James Marcout, Patricia Bauer [CDS]  30-Apr-1999