Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Full Refereed Journal Article (PDF/Postscript)
· Full Refereed Scanned Article (GIF)
· References in the article
· Citations to the Article (40) (Citation History)
· Refereed Citations to the Article
· SIMBAD Objects (21)
· NED Objects (1)
· Also-Read Articles (Reads History)
· Translate This Page
Oosterhoff dichotomy in the Galaxy and globular clusters in the Large Magellanic Cloud
Bono, Giuseppe; Caputo, Filippina; Stellingwerf, Robert F.
AA(Obsservatorio Astronomico di Trieste, Trieste, Italy), AB(Obsservatorio Astronomico di Trieste, Trieste, Italy), AC(Los Alamos National Lab., Los Alamos, NM, US)
The Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 423, no. 1, p. 294-304 (ApJ Homepage)
Publication Date:
NASA/STI Keywords:
Galactic Clusters, Globular Clusters, Horizontal Branch Stars, Magellanic Clouds, Stellar Evolution, Hertzsprung-Russell Diagram, Metallicity, Stellar Motions
Bibliographic Code:


The long-standing problem of the Oosterhoff dichotomy is studied within the framework of up-to-date convective pulsating models and synthetic horizontal-branch (HB) computations. It is shown that the observed properties of RR Lyrae-rich Galactic globular clusters can be put in agreement with theoretical prescriptions for a constant original helium (Y(MS) is approximately 0.23), on condition that in Oosterhoff type I clusters the transition between ab- and c-type RR Lyrae variables occurs near the blue edge for fundamental mode of pulsation, whereas in Oosterhoff type II it is near the red edge for first-overtone mode. Since type I clusters have redder HB morphology than type II systems, such an evidence should support the suggestion that the RRab/RRc transition depends on the evolutionary history of the variables, as was suggested early on by van Albada & Baker (1973). The analysis of the 'Oosterhoff-intermediate' clusters in the Large Magellanic Cloud strengthens this hypothesis still more. In fact, they turn out to represent the observational counterpart of a predicted class of clusters where, as a consequence of evolutionary track morphology and hysteresis in the pulsation as well, the mean period of ab-type variables shoud vary from Oosterhoff type I to Oosterhoff type II values. On these grounds, both the Oosterhoff groups in the Galaxy and the Oosterhoff-intermediate clusters in the large Magellanic Cloud could be explained within the same theoretical scenario, the different pulsational properties being caused by a combination of HB morphology with metallicity.

Printing Options

Print whole paper
Print Page(s) through

Return 600 dpi PDF to Acrobat/Browser. Different resolutions (200 or 600 dpi), formats (Postscript, PDF, etc), page sizes (US Letter, European A4, etc), and compression (gzip,compress,none) can be set through the Printing Preferences

More Article Retrieval Options

HELP for Article Retrieval

Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)


Find Similar Abstracts:

Use: Authors
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
arXiv e-prints