The radio structure of S5 1803+784 |
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| Authors: | S Britzen A Witzel T P Krichbaum T Beckert R M Campbell C Schalinski J Campbell |
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| Institution: | INAF - Telescopio Nazionale Galileo, 38700 Santa Cruz de La Palma, Spain;INAF - Osservatorio Astronomico di Bologna - Via Ranzani 1, I-40127 Bologna, Italy;INAF - Osservatorio Astronomico di Roma - Via dell'Osservatorio 5, I-00040 Monte Porzio, Italy;ESO, Alonso de Cordova 3107, Vitacura, Santiago, Chile |
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| Abstract: | We present deep CCD BVI photometry of the distant, old open cluster Berkeley 22, covering from the red giant branch (RGB) to about six magnitudes below the main-sequence (MS) turn-off. Using the synthetic colour–magnitude diagram method with three different types of stellar evolutionary tracks, we estimate values and theoretical uncertainties of the distance modulus ( m ? M )0, reddening E ( B ? V ), age τ and approximate metallicity. The best fit to the data is obtained for 13.8 ≤ ( m ? M )0≤ 14.1, 0.64 ≤ E ( B ? V ) ≤ 0.65, 2.0 ≤τ≤ 2.5 Gyr (depending on the amount of overshooting from convective regions adopted in the stellar models) and solar metallicity. |
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| Keywords: | Hertzsprung–Russell (HR) diagram open clusters and associations: general open clusters and associations: individual: Berkeley 22 |
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