Stellar populations of classical and pseudo-bulges for a sample of isolated spiral galaxies

In this paper we present the stellar population synthesis results for a sample of 75 bulges in isolated spiral Sb-Sc galaxies, using the spectroscopic data from the Sloan Digital Sky Survey and the STARLIGHT code. We find that both pseudo-bulges and classical bulges in our sample are predominantly composed of old stellar populations, with mean mass-weighted stellar age around 10 Gyr. While the stellar population of pseudo-bulges is, in general, younger than that of classical bulges, the difference is not significant, which indicates that it is hard to distinguish pseudo-bulges from classical bulges, at least for these isolated galaxies, only based on their stellar populations. Pseudo-bulges have star formation activities with relatively longer timescale than classical bulges, indicating that secular evolution is more important in this kind of systems. Our results also show that pseudo-bulges have a lower stellar velocity dispersion than their classical counterparts, which suggests that classical bulges are more dispersion-supported than pseudo-bulges.Comment: 10 pages, 8 figures. Accepted for publication in Astrophysics & Space Scienc

The Role of Evolutionary Age and Metallicity in the Formation of Classical Be Circumstellar Disks II. Assessing the Evolutionary Nature of Candidate Disk Systems

(Abridged version) We present the first detailed imaging polarization observations of six SMC and six LMC clusters, known to have large populations of B-type stars which exhibit excess H-alpha emission, to constrain the evolutionary status of these stars and hence better establish links between the onset of disk formation in classical Be stars and cluster age and/or metallicity. The wavelength dependence of our intrinsic polarization data provides a diagnostic of the dominant and any secondary polarigenic agents present, enabling us to discriminate pure gas disk systems, i.e. classical Be stars, from composite gas plus dust disk systems, i.e. Herbig Ae/Be or B[e] stars. Our intrinsic polarization results, along with available near-IR color information, strongly supports the suggestion of Wisniewski et al. that classical Be stars are present in clusters of age 5-8 Myr, and contradict assertions that the Be phenomenon only develops in the second half of a B star's main sequence lifetime, i.e. no earlier than 10 Myr. Comparing the polarimetric properties of our dataset to a similar survey of Galactic classical Be stars, we find that the prevalence of polarimetric Balmer jump signatures decreases with metallicity. We speculate that these results might indicate that either it is more difficult to form large disk systems in low metallicity environments, or that the average disk temperature is higher in these low metallicity environments. We have characterized the polarimetric signatures of all candidate Be stars in our data sample and find ~25% are unlikely to arise from true classical Be star-disk systems.Comment: 30 pages, accepted by ApJ, emulateapj5 forma

Investigating musical performance: Commonality and diversity amongst classical and non-classical musicians

The research project 'Investigating Musical Performance: Comparative Studies in Advanced Musical Learning' was devised to investigate how classical, popular, jazz and Scottish traditional musicians deepen and develop their learning about performance in undergraduate, postgraduate and wider music community contexts. The aim of this paper is to explore the findings relating to attitudes towards the importance of musical skills, the relevance of musical activities and the nature of musical expertise. Questionnaire data obtained from the first phase of data collection (n = 244) produced evidence of differences and similarities between classical and non-classical musicians. While classical musicians emphasised the drive to excel musically and technically and prioritised notation-based skills and analytical skills, non-classical musicians attached greater importance to memorising and improvising. Regardless of genre, the musicians all considered practical activities such as practising, rehearsing, taking lessons and giving performances to be relevant. However, while classical musicians attached greater relevance to giving lessons and solo performances, their non-classical colleagues considered making music for fun and listening to music within their own genre to be more relevant. Some underlying processes that may have accounted for the differences in attitudes are explored, including musical influences, age of initial engagement with music and educational background. Points of similarity and differences are discussed, and possibilities for the two musical trajectories to inform and learn from each other are highlighted

Perceptions and predictions of expertise in advanced musical learners

The aim of this article was to compare musicians' views on (a) the importance of musical skills and (b) the nature of expertise. Data were obtained from a specially devised web-based questionnaire completed by advanced musicians representing four musical genres (classical, popular, jazz, Scottish traditional) and varying degrees of professional musical experience (tertiary education music students, portfolio career musicians). Comparisons were made across musical genres (classical vs. other-than-classical), gender, age and professional status (student musicians vs. portfolio career musicians). Musicians' 'ideal' versus 'perceived' levels of musical skills and expertise were also compared and factors predicting musicians' self-reported level of skills and expertise were investigated. Findings suggest that the perception of expertise in advanced musical learners is a complex phenomenon that relates to each of four key variables (gender, age, musical genre and professional experience). The study also shows that discrepancies between advanced musicians' ideal and self-assessed levels of musical skills and expertise are closely related to gender and professional experience. Finally, characteristics that predict and account for variability in musicians' views and attitudes regarding musical expertise and self-assessments of personal expertise levels are highlighted. Results are viewed in the context of music learning and implications for music education are discussed

Classical Cepheid Pulsation Models. X. The Period-Age Relation

We present new Period-Age (PA) and Period-Age-Color (PAC) relations for fundamental and first overtone classical Cepheids. Current predictions rely on homogeneous sets of evolutionary and pulsation models covering a broad range of stellar masses and chemical compositions. We found that PA and PAC relations present a mild dependence upon metal content. Moreover, the use of different PA and PAC relation for fundamental and first overtone Cepheids improves the accuracy of age estimates in the short-period (log P < 1) range (old Cepheids), because they present smaller intrinsic dispersions. At the same time, the use of the PAC relations improves the accuracy in the long-period (log P >= 1) range (young Cepheids), since they account for the position of individual objects inside the instability strip. We performed a detailed comparison between evolutionary and pulsation ages for a sizable sample of LMC (15) and SMC (12) clusters which host at least two Cepheids. In order to avoid deceptive uncertainties in the photometric absolute zero-point, we adopted the homogeneous set of B,V,I data for clusters and Cepheids collected by OGLE. We also adopted the same reddening scale. The different age estimates agree at the level of 20 % for LMC clusters and of 10 % for SMC clusters. We also performed the same comparison for two Galactic clusters (NGC6067, NGC7790) and the difference in age is smaller than 20 %. These findings support the use of PA and PAC relations to supply accurate estimates of individual stellar ages in the Galaxy and in external Galaxies. The main advantage of this approach is its independence from the distance.Comment: 16 pages, 10 postscript figures, accepted for publication on Ap