Pismis 20: One or two clusters?

We present <i>UBVRI</i> polarimetric observations of stars in the direction of the open cluster Pismis 20 and WR 67. It is found that the observed members segregate polarimetrically into two groups, with different associated mean P<SUB>max</SUB> (4.31 and 6.08% respectively)....

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Detalles Bibliográficos
Autores: Orsatti, Ana María, Vega, Ema Irene, Marraco, Hugo Gustavo
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2003
País:Argentina
Institución:Universidad Nacional de La Plata
Repositorio:SEDICI (UNLP)
Idioma:inglés
OAI Identifier:oai:sedici.unlp.edu.ar:10915/84862
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84862
Access Level:acceso abierto
Palabra clave:Ciencias Astronómicas
ISM: dust, extinction
Open clusters and associations: individual: Pis20
Stars: individual: WR67
Technique: polarimetric
Descripción
Sumario:We present <i>UBVRI</i> polarimetric observations of stars in the direction of the open cluster Pismis 20 and WR 67. It is found that the observed members segregate polarimetrically into two groups, with different associated mean P<SUB>max</SUB> (4.31 and 6.08% respectively). Although in the literature these stars are considered as members of the same cluster, the polarized light from these groups clearly differs. There are two possible explanations: very efficient polarizing dust particles exists between certain members of the cluster; or else Pismis 20 is composed of different groupings superimposed along the line of sight. WR 67 belongs to the group more affected by the dust.