SIMBAD references

2002A&A...395..823P - Astronomy and Astrophysics, volume 395, 823-828 (2002/12-1)

CCD photometric search for peculiar stars in open clusters. IV. Collinder 272, Pismis 20, Lyngå 14, NGC 6396 and NGC 6611.


Abstract (from CDS):

The time scale on which chemical peculiarity in upper main sequence stars begins is unknown.
Result. from the Hipparcos measurements indicate that the classical chemically peculiar (CP) stars occupy the whole area from the zero age main sequence to the terminal age main sequence (Gomez et al., 1998A&A...336..953G). However, Hubrig et al. (2000ApJ...539..352H) reported that the magnetic fields appear only in stars that have already completed at least approximately 30% of their main sequence life time. Previous observations in the very young Orion OB1 and Scorpio-Centaurus associations (Joncas & Borra, 1981A&A....94..134J; Borra et al., 1982A&A...111..117B) reveal a percentage of chemically peculiar stars that is significantly smaller (less than 5%) than that of the galactic field (up to 25%). This already indicates that the phenomenon needs at least several 106yr to appear. Since no further observations have been published since then, we have observed the five very young (1Myr≤age≤25Myr) open clusters Collinder 272, Pismis 20, Lyngå 14, NGC 6396 and NGC 6611. Photometry from 250 CCD frames in the three filter Δa-system results in very low detection limits (0.008 to 0.015mag). We find no single photometrically chemically peculiar candidate in approximately 460 observed cluster members in the five program clusters. From the number of observed objects we deduce upper limits between 0.6% and 2.4% for the incidence of CP stars for the four observed aggregates.

Abstract Copyright:

Journal keyword(s): stars: chemically peculiar - stars: early-type - techniques: photometric - open clusters and associations: general

VizieR on-line data: <Available at CDS (J/A+A/395/823): table4.dat table5.dat table6.dat table7.dat table8.dat>

Nomenclature: Table 4: Cl* Collinder 272 PPM NNN (Nos 1-111). Table 5: Cl* Pismis 20 PPM NNN (Nos 1-238). Table 6: Cl* Lynga 14 PPM NN (Nos 1-53). Table 7: Cl* NGC 6396 PPM NNN (Nos 1-105). Table 8: Cl* NGC 6611 PPM NN (Nos 1-79).

Simbad objects: 499

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