Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-26T03:46:18.915Z Has data issue: false hasContentIssue false
  • English
  • Français

Are there carbon stars in the Bulge?

Published online by Cambridge University Press:  25 May 2016

Yuen Keong Ng
Yuen Keong Ng*
Affiliation:
Padova Observatory, Vicolo dell'Osservatorio 5, I-35122 Padua, Italy

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.

The Bulge carbon stars have been a mystery since their discovery by Azzopardi et al. (1991), because they are about too faint to be regarded as genuine AGB stars, if located inside the metal-rich Bulge . Part of the mystery can be solved if these carbon stars are related to the Sagittarius dwarf galaxy . They are in that case not old and metal-rich, but young, ∼0.1 Gyr, with SMC-like metallicity (Ng 1998).

The σRV = 113 ± 14 km s−1 (Tyson & Rich 1991) radial velocity dispersion of the stars appears to be consistent with Bulge membership. On the other hand, a similar velocity dispersion could be the result from an induced star formation event when the SDG crosses the galactic midplane. It is suggested that the carbon stars are tracers of such an event and that they therefore are located at distances related to the SDG. However, the majority of the carbon stars are not member of the SDG, nor are they similar to the C-stars which are member of the SDG.

The radial velocities can be used to determine a possible membership to the SDG. However, they do not give information about the distance of the stars. In particular, if the stars are located at a distance comparable to the SDG. This implies that only the period-luminosity relation (Groenewegen & Whitelock 1996) can be used to distinguish unambiguously if the carbon stars are located at Bulge-like or SDG-like distances. Thus far only carbon stars with reliable periods have been identified at a SDG related distance (Ng & Schultheis 1997; Whitelock 1998).

Type
Part 6. AGB Stars as a Population of Various Galaxies
Information
Symposium - International Astronomical Union , Volume 191: Asymptotic Giant Branch Stars , 1999 , pp. 545 - 550
Copyright
Copyright © Astronomical Society of the Pacific 1999 

References

Azzopardi, M., Lequeux, J., Rebeirot, E., Westerlund, B.E., 1991, A&AS 88, 265 (ALRW91) Google Scholar
Bertelli, G., Bressan, A., Chiosi, C., Fagotto, F., Nasi, E., 1994, A&AS 106, 275 Google Scholar
Bland-Hawthorn, J., Veilleux, S., Cecil, G.N., et al., 1998, MNRAS 299, 611 Google Scholar
Carraro, G., Ng, Y.K., Portinari, L., 1998, MNRAS 296, 1045 Google Scholar
Da Costa, G.S., Armandroff, T.E., 1995, AJ 109, 2533 CrossRefGoogle Scholar
Groenewegen, M.A.T., Whitelock, P.A., 1996, MNRAS 281, 1347 Google Scholar
Ibata, R.A., Lewis, G.F., 1998, ApJ 500, 575 Google Scholar
Ibata, R.A., Razoumov, A.O., 1998, A&A 336, 130 Google Scholar
Ibata, R.A., Gilmore, G., Irwin, M.J., 1994, Nature 370, 194 Google Scholar
Ibata, R.A., Gilmore, G., Irwin, M.J., 1995, MNRAS 277, 781 CrossRefGoogle Scholar
Ibata, R.A., Wyse, R.F.G., Gilmore, G., et al., 1997, AJ 113, 635 Google Scholar
Irwin, M., Ibata, R., Gilmore, G., et al., 1996, in ‘Formation of the galactic halo … inside and out’ , ASP Conf. Series 92, Morrison, H. and Sarajedini, A. (eds.), p. 84 Google Scholar
Lequeux, J., 1990, in ‘From Miras to planetary nebulae: which path for stellar evolution?’ , Mennessier, M.-O. and Omont, A. (eds.), Editions Frontières, p. 273 Google Scholar
Lin, D.N.C., 1996, in ‘Gravitational dynamics‘, Lahav, O., Terlevich, E. and Terlevich, R.J. (eds.), Cambridge University Press, p. 15 Google Scholar
Mighell, K., Armandroff, T., Sarajedini, A., et al., 1998, in ‘Galaxy interaction at low and high redshift’ , IAU Symposium 186, ed. Sanders, D.B., Kluwer, in press Google Scholar
Nair, V., Miralda-Escudé, J., 1998, ApJ submitted (astro-ph/9805278) Google Scholar
Ng, Y.K., 1997, A&A 328, 211 Google Scholar
Ng, Y.K., 1998, A&A 338, 435 Google Scholar
Ng, Y.K., Schultheis, M., 1997, A&AS 123, 115 Google Scholar
Paczyński, B., 1996, ARA&A 34, 419 Google Scholar
Scholz, R.-D., Irwin, M., Odenkirchen, M., Meusinger, H., 1998, A&A 333, 531 Google Scholar
Tyson, N., Rich, R.M., 1991, ApJ 367, 547 (TR91) CrossRefGoogle Scholar
Westerlund, B.E., Lequeux, J., Azzopardi, M., Rebeirot, E., 1991, A&A 244, 367 Google Scholar
Whitelock, P.A., 1998, in ‘Pulsating Stars - Recent Developments in Theory and Observation‘, Takeuti, M. and Sasselov, D. (eds.), Universal Academic Press, Tokyo, in press Google Scholar
Whitelock, P.A., Irwin, M., Catchpole, R.M., 1996, New Astronomy 1, 57 Google Scholar