The Optical Gravitational Lensing Experiment. Population Effects on the Mean Brightness of the Red Clump Stars

• Autorzy: Udalski A.
• Języki publikacji: EN

Abstrakty

EN

We present an empirical test indicating that the mean I-band magnitude of the red clump stars, used as the standard candle in the recent distance determinations to the Magellanic Clouds and other objects, is age independent for intermediate age (2-10 Gyr) stars. Fifteen star clusters of age ≈1.5-12 Gyr from the LMC and SMC (ESO121SC03, SL663, NGC 2155, NGC 2121, SL388, SL862, NGC 121, L1, KRON3, NGC 416, L113, NGC 339, L11, NGC 419, NGC 411) were observed and their color-magnitude diagrams are presented. The mean I-band brightness of the red clump in these clusters is constant and its mean extinction-free magnitude is: I₀=17.88±0.05 mag and I₀=18.31±0.07 mag at the mean metallicity of -0.8 dex and -1.2 dex for the LMC and SMC clusters, respectively. For older objects (>10 Gyr) the brightness of the red clump, which converts into the red part of the horizontal branch, fades by about 0.3-0.4 mag, setting an important limitation on the red clump stars method of distance determination. The red clump distance moduli to the Magellanic Clouds from the new independent data set are: m-M=18.18±0.06 mag and m-M=18.65±0.08 mag for the LMC and SMC, respectively, in very good agreement with previous determinations. Weak dependence of the mean I-band brightness of the red clump on metallicity and its independence of age for intermediate age population (2-10 Gyr) of stars as well as the most precise calibration as compared to other standard candle candidates makes the red clump stars method one of the most accurate steps in the distance scale ladder. Key words: Magellanic Clouds - Galaxies: distances and redshifts - distance scale - clusters individual: ESO121SC03, SL663, NGC 2155, NGC 2121, SL388, SL862, NGC 121, L1,

Słowa kluczowe

EN

Magellanic Clouds; galaxies: distances and redshifts; distance scale; clusters individual: ESO121SC03; clusters individual: SL663; clusters individual: NGC 2155; clusters individual: NGC 2121; clusters individual: SL388; clusters individual: SL86; clusters individual: NGC 121; clusters individual: L1; clusters individual: KRON3; clusters individual: NGC 416; clusters individual: L113; clusters individual: NGC 339; clusters individual: L11; clusters individual: NGC 419; clusters individual: NGC 411

• Wydawca: Copernicus Foundation for Polish Astronomy
• Czasopismo: Acta Astronomica
• Rocznik: 1998
• Tom: Vol. 48, No. 3
• Strony: 383--404
• Opis fizyczny: Bibliogr. 39 poz., tab., wykr.

Twórcy

autor

Udalski A.

• Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

Bibliografia

• Beaulieu, J.P., and Sackett, P.D. 1998, Astron. J., 116, 209.
• Bica, E., Dottori, H., and Pastoriza, M. 1987, Astron. Astrophys., 156, 261.
• Bica, E., Geisler, D., Dottori, H., Clari´a, J.J., Piatti, A.E., and Santos Jr, J.F.C. 1998, Astron. J., 116, 723.
• Caldwell, J.A.R., and Laney C.D. 1991, in IAU Symp. No. 148, TheMagellanic Clouds, Eds. Haynes, R. and Milne, D., Kluwer, Dordrecht, p. 249.
• Cole, A.A. 1998, Astrophys. J. Letters, 500, L137.
• Corsi, C.E., Buonanno, R., Fusi Pecci, F., Ferraro, F.R., Testa, V., and Greggio, L. 1994, MNRAS, 271, 385.
• Da Costa, G.S., and Mould, J.R. 1986, Astrophys. J., 305, 214.
• Da Costa, G.S., and Hatzidimitriou, D. 1998, Astron. J., 115, 1934.
• Gardiner, L.T., and Hatzidimitriou, D. 1992, MNRAS, 257, 195.
• Girardi, L., Groenewegen, M.A.T., Weiss, A., and Salaris, M. 1998, MNRAS, submitted, (astroph/9805127).
• Graham J.A. 1975, P.A.S.P., 87, 641.
• Harris, J., Zaritsky, D., and Thompson, I. 1997, Astron. J., 114, 1933.
• Kaluzny, J., Krzemiński, W., Mazur, B., Wysocka, A., and Stępień, K. 1997, Acta Astron., 47, 249.
• Kaluzny, J., Kubiak, M., Szymański, M., Udalski, A., Krzemiński, W., Mateo, M., and Stanek, K.Z. 1998a, Astron. Astrophys. Suppl. Ser., 128, 19.
• Kaluzny, J., Wysocka, A., Stanek, K.Z., Krzemiński, W., 1998b, Acta Astron., 48, 439.
• Kennicutt Jr., R.C., Freedman, W.L., and Mould, J.R. 1995, Astron. J., 110, 1476.
• Landolt, A.U. 1992, Astron. J., 104, 372.
• Mighell, K.J., Sarajedini, A., French, R.S. 1998, Astrophys. J. Letters, 494, L189.
• Oestreicher, M.O., and Schmidt-Kaler, Th. 1996, Astron. Astrophys. Suppl. Ser., 117, 303.
• Olszewski, E.W., Suntzeff, N.B., and Mateo, M. 1996, ARA&A, 34, 511.
• Paczyński, B. 1997, in: "The Extragalactic Distance Scale STScI Symposium", Baltimore, Cambridge University Press, 273 (astro-ph/9608094).
• Paczyński B., and Stanek, K.Z. 1998, Astrophys. J. Letters, 494, L219.
• Pietrzyński, G., Udalski, A., Szymański, M., Kubiak, M., Woźniak, P., and Żebruń, K. 1998, Acta Astron., 48, 175.
• Reid, N., and Freedman, W.L. 1994, MNRAS, 267, 821.
• Rich, R.M., Da Costa, G.S., and Mould, J.R. 1984, Astrophys. J., 286, 517.
• Sarajedini, A. 1998, Astron. J., 116, 738.
• Sarajedini, A., Lee, Y.W., and Lee, D.H. 1995, Astrophys. J., 450, 712.
• Schechter, P.L., Saha, K., and Mateo, M. 1993, P.A.S.P., 105, 1342.
• Schlegel, D.J., Finkbeiner, D.P., and Davis, M. 1998, Astrophys. J., 500, 525.
• Skillen, I., Fernley, J.A., Stobie, R.S., and Jameson, R.F. 1993, MNRAS, 265, 301.
• Stanek, K.Z., and Garnavich, P.M. 1998, Astrophys. J. Letters, 503, L131.
• Stanek, K.Z, Zaritsky, D., and Harris, J. 1998, Astrophys. J. Letters, 500, L141.
• Stetson, P.B., Hesser, J.E. and Smecker-Hane, T.A. 1998, P.A.S.P., 110, 533.
• Udalski, A., Kubiak, M., and Szymański, M. 1997, Acta Astron., 47, 319.
• Udalski, A. 1998, Acta Astron., 48, 113.
• Udalski, A., Szymański, M., Kubiak, M., Pietrzyński, G., Woźniak, P., and Żerbuń, K. 1998a, Acta Astron., 48, 1.
• Udalski, A., Szymański, M., Kubiak, M., Pietrzyński, G., Woźniak, P., and Żerbuń, K. 1998b, Acta Astron., 48, 147.
• Walker, A.R., and Mack, P. 1988, Astron. J., 96, 872.
• Zaritsky, D., and Lin, D.B.C. 1997, Astron. J., 114, 2545.