New Observations and Period Change Study for the Anomalous Cepheid in M 92

• Autorzy: Osborn W. , Kopacki G. , Haberstroh J.
• Języki publikacji: EN

Abstrakty

EN

New observations of the variable star V7 in the globular cluster M 92 have been used to determine the parameters of its B, V and I_C light curves. The star's classification as an anomalous Cepheid type is confirmed. The asymmetric shape of the light curve and position in the observed period-luminosity relation for anomalous Cepheids indicate the star is pulsating in the fundamental mode. Data from photographic plates, extending back to 1900, have been combined with published material and recent CCD observations to carry out a period change study. No evidence of a period change is found. Expected period change rates have been calculated using theoretical relations for the pulsational periods of anomalous Cepheids and evolutionary tracks for metal-poor horizontal branch stars with masses 1.0≤M/M_sun≤1.6. Only models for stars close to central helium exhaustion show measurable rates, which indicates V7 is in the core helium burning phase of evolution.

Słowa kluczowe

EN

globular clusters: individual: M 92; stars: individual: M 92 V7; stars: variables: Cepheids

• Wydawca: Copernicus Foundation for Polish Astronomy
• Czasopismo: Acta Astronomica
• Rocznik: 2012
• Tom: Vol. 62, No. 4
• Strony: 377--388
• Opis fizyczny: Bibliogr. 30 poz., tab., wykr.

Twórcy

autor

Osborn W.

• Yerkes Observatory, 373 West Geneva Street, Williams Bay, WI 53191, USA

autor

Kopacki G.

• Astronomical Institute, University of Wrocław, ul. Kopernika 11, 51-622 Wrocław, Poland

autor

Haberstroh J.

• Yerkes Observatory, 373 West Geneva Street, Williams Bay, WI 53191, USA
• Student Intern at Yerkes Observatory from Waukesha West High School, Waukesha, WI, USA

Bibliografia

• Alard, C., and Lupton, R.H. 1998, ApJ, 503, 325.
• Bergbusch, P.A., and Stetson, P.B. 2009, AJ, 138, 1455.
• Bertelli, G., Girardi, L., Marigo, P., and Nasi, E. 2008, A&A, 484, 815.
• Caputo, F., Castellani, V., Degl’Innocenti, S., Fiorentino, G., and Marconi, M. 2004, A&A, 424, 927.
• Carretta, E., Bragaglia, A., Graton, R., D’Orazi, V., and Lucatello, S. 2009, A&A, 508, 695.
• Carson, R., and Stothers, R. 1982, ApJ, 259, 740.
• Di Criscienzo, M., Marconi, M., Caputo, F., and Cassisi, S. 2007, A&A, 471, 893.
• Fiorentino, G., Limongi, M., Caputo, F., and Marconi, M. 2006, A&A, 460, 155.
• Guthnick, P., and Prager, R. 1925, Sitz d. Preuss Akad Weis., 27, 508.
• Hachenberg, O. 1939, Zeitschrift für Astrophysik, 18, 49.
• Harris, W.E. 2010, arXiv:1012.3224.
• Kadla, Z.I., Yablokova, N.V., Gerashchenko, A.N., and Spasova, N. 1983, Peremennye Zvezdy, 21, 827.
• Kheilo, E.S. 1967, Peremennye Zvezdy, 16, 213.
• Kopacki, G. 2001a, “Wiekowe zmiany okresów gwiazd typu RR Lyrae wybranych gromad kulistych” PhD Thesis, Univ. Wroclaw.
• Kopacki, G. 2001b, A&A, 369, 862.
• Kopacki, G. 2007, Acta Astron., 57, 49.
• Kopacki, G., Drobek, D., Kołaczkowski, Z., and Połubek, G. 2008, Acta Astron., 58, 373.
• Marconi, M., Fiorentino, G., and Caputo, F. 2004, A&A, 417, 1101.
• Matsunaga, N., et al. 2006, MNRAS, 370, 1979.
• McCarthy, J.K., and Nemec, J.M. 1997, ApJ, 482, 203.
• Nassau, J.J. 1938, ApJ, 87, 361.
• Pritzl, B.J., et al. 2002, AJ, 124, 1464.
• Rees, R.F. 1992, AJ, 103, 1573.
• Ruelas-Mayorga, A., and Sánchez, L.J. 2008, Rev. Mex. de Astron. y Astrof. (Serie de Conferencias), 34, 137.
• Shapley, H. 1922, Harvard Bull., 773, 1.
• Sills, A., Karakas, A., and Lattanzio, J. 2009, ApJ, 692, 1411.
• Smolec, R., et al. 2012, MNRAS, 419, 2407.
• Soszyński, I., et al. 2008, Acta Astron., 58, 293.
• Stetson, P.B. 2000, PASP, 112, 925.
• Wallerstein, G. 2002, PASP, 114, 689.