A polarimetric survey for dust in 47 Tucanae

We present linear polarization measurements in the V band for 77 stars in the field of the globular cluster 47 Tucanae (NGC 104) and for 14 regions free of bright stars, located along an elliptical isophotal contour of the cluster, as well as UBVRI measurements for the cluster nucleus. The observati...

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Detalles Bibliográficos
Autores principales: Forte, Juan Carlos, Bassino, Lilia Patricia, Vega, Ema Irene, Pellizza González, Leonardo J., Cellone, Sergio Aldo, Méndez, Mariano R.
Formato: Articulo
Lenguaje:Inglés
Publicado: 2002
Materias:
Ciencias Astronómicas
Dust, extinction
Globular clusters: individual (NGC 104 = 47 Tucanae)
Polarization
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/83525
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-83525
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Astronómicas
Dust, extinction
Globular clusters: individual (NGC 104 = 47 Tucanae)
Polarization
spellingShingle Ciencias Astronómicas
Dust, extinction
Globular clusters: individual (NGC 104 = 47 Tucanae)
Polarization
Forte, Juan Carlos
Bassino, Lilia Patricia
Vega, Ema Irene
Pellizza González, Leonardo J.
Cellone, Sergio Aldo
Méndez, Mariano R.
A polarimetric survey for dust in 47 Tucanae
topic_facet Ciencias Astronómicas
Dust, extinction
Globular clusters: individual (NGC 104 = 47 Tucanae)
Polarization
description We present linear polarization measurements in the V band for 77 stars in the field of the globular cluster 47 Tucanae (NGC 104) and for 14 regions free of bright stars, located along an elliptical isophotal contour of the cluster, as well as UBVRI measurements for the cluster nucleus. The observations show variable foreground polarization that, once removed, leaves marginally significant polarization residuals for the nonvariable bright red giants. Although these residuals are small, there is a systematic trend in the sense that the larger ones are seen toward the south of the cluster (in a direction opposite to that of the cluster proper motion). In contrast, most of the variable stars do show significant intrinsic polarization. The behavior of the star-free regions is similar to that of the nonvariable stars and sets an upper limit to the possible existence of a global pattern of scattered (and polarized) intracluster light in the V band. In turn, the multicolor observations of the cluster nucleus cannot be fitted with a Serkowski law and exhibit a polarization excess in both U and B. This polarization could be explained as a combination of the foreground interstellar component and another component arising from dust located in the nucleus and illuminated by a bright blue post-asymptotic giant branch star (at 48″ from the cluster center). Inspection of a set of archival Hubble Space Telescope Wide Field Planetary Camera 2 images reveals the presence of a number of dark patches in the innermost regions of the cluster. A prominent patch (some 5″ 3″ in size) located 12″ from the cluster center and with a position angle (north to east) of 120° has a slightly different polarization compared with that of the cluster nucleus and appears to be a good candidate for identification as a dust globule within the cluster.
format Articulo
Articulo
author Forte, Juan Carlos
Bassino, Lilia Patricia
Vega, Ema Irene
Pellizza González, Leonardo J.
Cellone, Sergio Aldo
Méndez, Mariano R.
author_facet Forte, Juan Carlos
Bassino, Lilia Patricia
Vega, Ema Irene
Pellizza González, Leonardo J.
Cellone, Sergio Aldo
Méndez, Mariano R.
author_sort Forte, Juan Carlos
title A polarimetric survey for dust in 47 Tucanae
title_short A polarimetric survey for dust in 47 Tucanae
title_full A polarimetric survey for dust in 47 Tucanae
title_fullStr A polarimetric survey for dust in 47 Tucanae
title_full_unstemmed A polarimetric survey for dust in 47 Tucanae
title_sort polarimetric survey for dust in 47 tucanae
publishDate 2002
url http://sedici.unlp.edu.ar/handle/10915/83525
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