Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-08-22
Astronomy and Astrophysics
Astrophysics
10 pages, 9 figures. Accepted for publication in A&A
Scientific paper
10.1051/0004-6361:20065816
During an analysis of optical spectra of 80 young star clusters in several nearby spiral galaxies, [O III] and [N II] emission lines were noted in some cases. Three of these emission line sources are identified as likely planetary nebula (PN) candidates and may represent a rare opportunity to study PNe whose progenitor stars are known to be of intermediate masses. This paper presents and discusses basic properties of the PN candidates and their host clusters. Based on the observed emission line fluxes, the excitation parameters and luminosities of the nebulae are derived. This allows a crude placement of the central stars in two of the objects on the H-R diagram, and their temperatures and luminosities are found to be consistent with post-AGB model tracks for a central star mass of about 0.60 Msun. Host cluster ages and masses are estimated from broad-band colours and by comparison with model SSP spectra. One of the host clusters has an age of 32-65 Myrs, corresponding to a main sequence turn-off mass of M(TO) = 6.6-9.0 Msun. For the other cluster the age is 282-407 Myrs, corresponding to M(TO) = 3.2-3.6 Msun. By estimating the number of stars evolving off the main sequence per year, a total of 6 PNe are expected in our full sample of 80 clusters for aPN lifetime of 10000 years. The factor of two disagreement with the actual observed number may be due, among other things, to uncertainties in PN lifetimes. It is interesting to note that all three PN candidates are associated with clusters which are more diffuse than average. While PNe have previously been found in some old globular clusters, the candidates identified here are among the first identified in young star clusters.
Larsen Soeren S.
Richtler Tom
No associations
LandOfFree
Planetary Nebula Candidates in Extragalactic Young Star Clusters does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Planetary Nebula Candidates in Extragalactic Young Star Clusters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Planetary Nebula Candidates in Extragalactic Young Star Clusters will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-572760