Hostname: page-component-cd9895bd7-gvvz8 Total loading time: 0 Render date: 2024-12-25T05:36:18.512Z Has data issue: false hasContentIssue false
  • English
  • Français

RR Lyrae to understand the Galactic halo

Published online by Cambridge University Press:  09 May 2016

Giuliana Fiorentino
Giuliana Fiorentino*
Affiliation:
INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127, Bologna, Italy email: [email protected]
Rights & Permissions [Opens in a new window]

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.

We present recent results obtained using old variable RR Lyrae stars on the Galactic halo structure and its connection with nearby dwarf galaxies. We compare the period and period-amplitude distributions for a sizeable sample of fundamental mode RR Lyrae stars (RRab) in dwarf spheroidals (~1300 stars) with those in the Galactic halo (~16'000 stars) and globular clusters (~1000 stars). RRab in dwarfs –as observed today– do not appear to follow the pulsation properties shown by those in the Galactic halo, nor they have the same properties as RRab in globulars. Thanks to the OGLE experiment we extended our comparison to massive metal–rich satellites like the dwarf irregular Large Magellanic Cloud (LMC) and the Sagittarius (Sgr) dwarf spheroidal. These massive and more metal–rich stellar systems likely have contributed to the Galactic halo formation more than classical dwarf spheroidals.

Finally, exploiting the intrinsic nature of RR Lyrae as distance indicators we were able to study the period and period amplitude distributions of RRab within the Halo. It turned out that the inner and the outer Halo do show a difference that may suggest a different formation scenario (in situ vs accreted).

Keywords

Galaxy: structureGalaxy: halostars: variables: RR Lyrae
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Issue S317: The General Assembly of Galaxy Halos: Structure, Origin and Evolution , August 2015 , pp. 77 - 82
Copyright
Copyright © International Astronomical Union 2016 

References

Carollo, D., et al. 2007, Nature, 450, 1020Google Scholar
Carollo, D., Beers, T. C., Chiba, M., et al. 2010, ApJ, 712, 692CrossRefGoogle Scholar
Clement, C. M., et al. 2001, AJ, 122, 2587Google Scholar
Drake, A. J., et al. 2013, ApJ, 763, 32Google Scholar
Eggen, O. J., Lynden-Bell, D., & Sandage, A. R. 1962, ApJ, 136, 748Google Scholar
Fiorentino, G., Bono, G., Monelli, M., et al. 2015, ApJ (Letters), 798, L12CrossRefGoogle Scholar
Helmi, A., et al. 2006, ApJ (Letters), 651, L121CrossRefGoogle Scholar
Leaman, R., VandenBerg, D. A., & Mendel, J. T. 2013, MNRAS, 436, 122CrossRefGoogle Scholar
Marín-Franch, A., Aparicio, A., Piotto, G., et al. 2009, ApJ, 694, 1498CrossRefGoogle Scholar
McConnachie, A. W. 2012, AJ, 144, 4CrossRefGoogle Scholar
Schönrich, R., Asplund, M., & Casagrande, L. 2011, MNRAS, 415, 3807Google Scholar
Schörck, T., Christlieb, N., Cohen, J. G., et al. 2009, A&A, 507, 817Google Scholar
Searle, L., & Zinn, R. 1978, ApJ, 225, 357CrossRefGoogle Scholar
Smith, H. A., Catelan, M., & Clementini, G. 2009, AIP-CP, 1170, 179Google Scholar
Soszyński, I., et al. 2009, AcA, 59, 1Google Scholar
Soszyński, I., Udalski, A., Szymański, M. K., et al. 2014, AcA, 64, 177Google Scholar
Stetson, P. B., Fiorentino, G., Bono, G., Bernard, E. J., Monelli, M., Iannicola, G., Gallart, C., & Ferraro, I. 2014, PASP, 126, 616Google Scholar
Szczygieł, D. M., Pojmański, G., & Pilecki, B. 2009, AcA, 59, 137Google Scholar
Tissera, P. B., Beers, T. C., Carollo, D., & Scannapieco, C. 2014, MNRAS, 439, 3128CrossRefGoogle Scholar
Tolstoy, E., Hill, V., & Tosi, M. 2009, A&AR, 47, 371Google Scholar
Venn, K. A., Irwin, M., Shetrone, M. D., Tout, C. A., Hill, V., & Tolstoy, E. 2004, AJ, 128, 1177CrossRefGoogle Scholar
Vincenzo, F., Matteucci, F., Vattakunnel, S., & Lanfranchi, G. A. 2014, MNRAS, 441, 2815Google Scholar
Vivas, A. K., et al. 2004, AJ, 127, 1158Google Scholar
Woźniak, P. R., Vestrand, W. T., Akerlof, C. W., et al. 2004, AJ, 127, 2436Google Scholar
York, D. G., Adelman, J., Anderson, J. E. Jr., et al. 2000, AJ, 120, 1579CrossRefGoogle Scholar
Zinn, R., Horowitz, B., Vivas, A. K., Baltay, C., Ellman, N., Hadjiyska, E., Rabinowitz, D., & Miller, L. 2014, ApJ, 781, 22CrossRefGoogle Scholar