Investigating potential planetary nebula/cluster pairs^{⋆,⋆⋆,⋆⋆⋆}

¹ Departamento de AstronomíaUniversidad de Concepción, Casilla 160-C, Concepción, Chile
e-mail: cmoni@ucn.cl
² Instituto de Astronomía, Universidad Católica del Norte, Av. Angamos 0610, Casilla 1280, Antofagasta, Chile
³ Halifax, Nova Scotia, B3K 5L3, Canada
⁴ Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970, RS, Porto Alegre Brazil
⁵ Department of Astronomy and Physics, Saint Mary’s University, Halifax, NS B3H 3C3, Canada
⁶ Departamento de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Casilla 5030, Valparaíso, Chile
⁷ Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago, Chile
⁸ Vatican Observatory, V 00120 Vatican City State, Italy
⁹ ESO – European Southern Observatory, Avda Alonso de Cordova, 3107, Casilla 19001, 8370134 Santiago, Chile
¹⁰ Dipartimento di Fisica e Astronomia, Universitá di Padova, via Marzolo 8, 35131 Padova, Italy

Received: 28 November 2012
Accepted: 3 November 2013

Abstract

Context. Fundamental parameters characterizing the end-state of intermediate-mass stars may be constrained by discovering planetary nebulae (PNe) in open clusters (OCs). Cluster membership may be exploited to establish the distance, luminosity, age, and physical size for PNe, and the intrinsic luminosity and mass of its central star.

Aims. Four potential PN-OC associations were investigated to assess the cluster membership for the PNe.

Methods. Radial velocities were measured from intermediate-resolution optical spectra, complemented with previous estimates in the literature. When the radial velocity study supported the PN/OC association, we analyzed whether other parameters (e.g., age, distance, reddening, central star brightness) were consistent with this conclusion.

Results. Our measurements imply that the PNe VBe 3 and HeFa 1 are not members of the OCs NGC 5999 and NGC 6067, respectively, and that they very likely belong to the background bulge population. Conversely, consistent radial velocities indicate that NGC 2452/NGC 2453 could be associated, but our results are not conclusive so additional observations are warranted. Finally, we demonstrate that all the available information point to He 2-86 being a young, highly internally obscured PN member of NGC 4463. New near-infrared photometry acquired via the Vista Variables in the Via Lactea ESO public survey was used in tandem with existing UBV photometry to measure the distance, reddening, and age of NGC 4463, finding d = 1.55 ± 0.10 kpc, E(B − V) = 0.41 ± 0.02, and τ = 65 ± 10 Myr, respectively. The same values should be adopted for the PN if the proposed cluster membership is confirmed.