Hostname: page-component-586b7cd67f-2brh9 Total loading time: 0 Render date: 2024-11-30T04:35:52.476Z Has data issue: false hasContentIssue false
  • English
  • Français

Observational Aspects of Slow Variables in Globular Clusters

Published online by Cambridge University Press:  12 April 2016

M. W. Feast
M. W. Feast*
Affiliation:
Radcliffe Observatory, Pretoria, South Africa

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

There are up to 14 known Mira variables in seven globular clusters, though several have not yet been confirmed as radial velocity members. The periods of only 5 are known, all near 200 days. The clusters seem to form a compact group of relatively metal rich clusters. In 3 or 4 cases spectroscopy shows that the giant branches of these clusters penetrate into the M types. The Mira-containing clusters also contain red variables of shorter period and smaller amplitude which are generally also M type stars. Stars apparently evolve to the red of the giant tip as variables of increasing amplitude and period. Effects of TiO blanketing on the (B — V) colours may be anticipated in these clusters.

Besides variables at the red giant tip the metal poor globular cluster ω Cen contains variables with strong TiO bands. Photometry, including recent J, H, K, L photometry by Glass shows that these stars are very cool objects. They indicate an extension of the giant branch considerably cooler than previously considered for metal poor clusters.

V1, NGC 121 in the Small Magellanic Cloud has a spectrum indicative of an SRd variable. It is not yet clear whether galactic stars similar to this star exist or not.

Type
Part III / Slow Variables in Population II Systems
Information
International Astronomical Union Colloquium , Volume 21: Variable Stars in Globular Clusters and in Related Systems , August 1973 , pp. 131 - 144
Copyright
Copyright © Reidel 1973

References

Andrews, P. J. and Lloyd Evans, T.: 1971, in Muller, A. (ed.), The Magellanic Clouds, Reidel, Dordrecht, p. 88.Google Scholar
Arp, H. C., Brueckel, F., and Lourens, J. v. B.: 1963, Astrophys. J. 137, 228.Google Scholar
Arp, H. C. and Hartwick, F. D. A.: 1971, Astrophys. J. 167, 499.Google Scholar
Brooke, A. L.: 1969, Ph.D. Thesis, Australian National University, Canberra.Google Scholar
Catchpole, R. M., Feast, M. W., and Menzies, J. W.: 1970, Observatory 90, 63.Google Scholar
Dickens, R. J., Feast, M. W., and Lloyd Evans, T.: 1972, Monthly Notices Roy. Astron. Soc, 159, 337.Google Scholar
Eggen, O. J.: 1972, Astrophys. J. 172, 639.Google Scholar
Feast, M. W.: 1963, Monthly Notices Roy. Astron. Soc. 125, 367.Google Scholar
Feast, M. W.: 1965, Observatory 85, 16.Google Scholar
Feast, M. W.: 1967, Observatory 87, 35.Google Scholar
Feast, M. W. and Thackeray, A. D.: 1960, Monthly Notices Roy. Astron. Soc. 120, 463.Google Scholar
Fourcade, C. R., Laborde, J. R., and Albarracin, J.: 1966, Atlas y Catálogo de estrellas variables en cúmulos globulares al sur de — 29°, Cordoba.Google Scholar
Hain, D. D.: 1969, Ph.D. Thesis, Australian National University, Canberra Google Scholar
Hartwick, F. D. A. and Sandage, A. R.: 1968, Astrophys. J. 153, 715.CrossRefGoogle Scholar
Joy, A. H.; 1949, Astrophys. J. 110, 105.CrossRefGoogle Scholar
Lee, T. A.: 1970, Astrophys. J. 162, 217.Google Scholar
Lloyd Evans, T. and Menzies, J. W.: 1971, Observatory 91, 35.Google Scholar
Martin, W. Ch.: 1938, Ann. Sterrew. Leiden 17, Part 2.Google Scholar
Osborne, W.: 1968, Observatory 88, 26.Google Scholar
Preston, G. W.: 1967, Publ. Astron. Soc. Pacific 79, 125.Google Scholar
Preston, G. W. and Wallerstein, G.: 1963, Astrophys. J. 138, 820.Google Scholar
Preston, G. W., Krzeminski, W., Smak, J., and Williams, J. A.: 1963, Astrophys. J. 137, 401.Google Scholar
Rosino, L.: 1966, Astrophys. J. 144, 903.CrossRefGoogle Scholar
Sandage, A. R. and Wallerstein, G.: 1960, Astrophys. J. 131, 598.Google Scholar
Sandage, A. R., Smith, L. L., and Norton, R. H.: 1966, Astrophys. J. 144, 894.Google Scholar
Smak, J. L: 1966, Ann. Rev. Astron. Astrophys. 4, 19.Google Scholar
Stephenson, C. B.: 1961, Astrophys. J. 66, 85.Google Scholar
Thackeray, A. D.: 1955, see Sawyer-Hogg, H. B., Publ. David Dunlap Observatory 2, No. 2.Google Scholar
Thackeray, A. D.: 1958, Monthly Notices Roy. Astron. Soc. 118, 117.Google Scholar
Tifft, W. G.: 1963, Monthly Notices Roy. Astron. Soc. 125, 199.Google Scholar