 The European working group on chemically peculiar stars of the upper main sequence. The first 10 years.; ; et al in The Messenger (1989), 55 A fraction of the Band A type stars have chemical peculiarities (CP). 4 subgroups are recognized: CP 1 or Am, CP2 or magnetic Ap (with enhanced Sr, Cr, Eu, Si lines), CP3 (ar non-magnetic Ap, with Hg Mn ... [more ▼] A fraction of the Band A type stars have chemical peculiarities (CP). 4 subgroups are recognized: CP 1 or Am, CP2 or magnetic Ap (with enhanced Sr, Cr, Eu, Si lines), CP3 (ar non-magnetic Ap, with Hg Mn enhanced) and CP4 (B type stars with He peculiarities, a fraction of them appear to be a hot extension of CP 2). [less ▲] Detailed reference viewed: 2 (0 ULg) The frequency of Ap-stars with long rotation periods; Manfroid, Jean  ; Renson, Pierre et alin Astronomy and Astrophysics (1984), 132 Light variability was observed over time intervals of months to years in the stars HD 55540, HD 71066, HD 94660, and HD 187474. The significance of these results is discussed in terms of the frequency of ... [more ▼] Light variability was observed over time intervals of months to years in the stars HD 55540, HD 71066, HD 94660, and HD 187474. The significance of these results is discussed in terms of the frequency of chemically peculiar CP2 stars showing (light) variability with periods longer than one month. This frequency, relative to the whole CP2 population, must lie somewhere between 4 and 16 percent. Observations, properly distributed in time, of a small subgroup of CP2 stars will be sufficient to obtain an accurate ratio of the number of LP-CP2 stars to the total number of CP2 stars. These observations, when continued until the periodicity is detected, could contribute also to the discussion whether these long periods should be identified with the rotation period. [less ▲] Detailed reference viewed: 3 (0 ULg)Observational Material / Ap-StarsManfroid, Jean ; in A Peculiar Newsletter (1982), 8 Not Available Detailed reference viewed: 19 (12 ULg) |
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