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J/PASP/98/1133      The open cluster NGC 346                    (Niemela+, 1986)
The young open cluster NGC 346 in the Small Magellanic Cloud
       NIEMELA V.S., MARRACO H.G, CABANNE M.L.
      <Publ. Astron. Soc. Pac. 98, 1133 (1986)>
      =1986PASP...98.1133N      (SIMBAD/NED Reference)
ADC_Keywords: Magellanic Clouds; Clusters, open; Photometry, CCD

Keywords: open cluster - CCD photometry - radial velocities - O-type stars


Abstract:
     We present CCD photometry and spectrographic observations for stars
     in the open cluster NGC 346, which excites the largest H II region
     in the Small Magellanic Cloud. These observations show that NGC 346
     is an extremely young cluster, containing more than 20 hot O-type
     stars. A radial-velocity study of the brightest stars, and also of
     the nearby supergiant Of star Sk 80, discloses atmospheric expansion
     due to strong stellar winds, but no large-amplitude radial-velocity
     variations due to short-period binary motion. However, two stars
     are probably longer period binaries.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1            31       58   NGC 346 VRI (Kron-Cousins) CCD photometry


Byte-by-byte Description of file: table1

   Bytes Format  Units   Label    Explanations

   1-  2  I2     ---     Id       Star number
   9- 13  F5.2   mag     Vmag     V magnitude
  16- 20  F5.2   mag     V-R      V-R colour index
  23- 27  F5.2   mag     V-I      V-I colour index
      31  I1     ---     Rem      [1-6]? Remarks (1)

Note (1): 1: integrated magnitude of a double star, not in Figure 3 and 4.
          2: data correspond only to the brightest member of the group.
          3: V observation affected by a cosmic ray, not in Figures 3 and 4.
          4: red star, not in Figure 4.
          5: integrated magnitude of a double star.
          6: probably non-member, far from cluster center, not in Figure 4.


Table2 : Spectral classification and absolute magnitudes of the
          brightest stars in NGC 346
-----------------------------------------------------------------------------
       Star       Spectral    Source   Mv     Remarks
                  Type
-----------------------------------------------------------------------------
        25        O8.5 III    a,c      -6.6   No. 2 in a
        26        O4 III(f)   a        -7.1   No. 1 in a
        28        O5-6: V:    c        -5.4   Only 1 weak spectrum
        29        O3 III(f)   b,c      -6.1   No. 3 in b
        30        O5-6 V      b,c      -5.9   No. 4 in b
        32        O4-5 V      c        -5.5
-----------------------------------------------------------------------------
        a: Walborn N.R., 1978, Ap.J. (Letters), 224, L133
        b: Walborn N. R. and Blades J.C., 1986, Ap.J. (Letters), 304, L17
        c: This study.

Historical Notes: Keupunched at CDS

(End)                      Marie-Jose Wagner, Patricia Bauer [CDS]   02-Mar-1995