Magnetically collimated jets with high mass flux |
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| Authors: | S Bogovalov K Tsinganos † |
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| Institution: | Kitt Peak National Observatory, National Optical Astronomy Observatories, PO Box 26732, Tucson, AZ 85726, USA; Special Astrophysical Observatory, Russian Academy of Sciences, N. Arkhyz, KChR 357147, Russia; Astronomical Observatory of Kiev University, 04053, Observatorna 3, Kiev, Ukraine; Departmento de Fisica, Grupo de Astronomia, Universidad de Concepcion, Casilla 160-C, Concepcion, Chile; Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany; UCO/Lick Observatory, University of California at Santa Cruz, Santa Cruz, CA 95064, USA; Department of Astronomy, University of Washington, PO Box 351580, Seattle, WA 98195, USA; Astronomy Department, Wesleyan University, Middletown, CT 06459, USA; Department of Astronomy, University of Michigan, 830 Dennison Building, Ann Arbor, MI 48109, USA |
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| Abstract: | We present HST /WFPC2 observations of UGC 4483, an irregular galaxy in the M81/NGC 2403 complex. Stellar photometry was carried out with HSTphot, and is complete to V ?26.0 and I ?24.7. We measure the red giant branch tip at I =23.56±0.10, and calculate a distance modulus of μ 0=27.53±0.12 (corresponding to a distance of 3.2±0.2 Mpc), placing UGC 4483 within the NGC 2403 subgroup. We were able to measure properties of a previously known young star cluster in UGC 4483, finding integrated magnitudes of V =18.66±0.21 and I =18.54±0.10 for the stellar contribution (integrated light minus H α and O iii ] contribution), corresponding to an age of ～10–15 Myr and an initial mass of ～104 M⊙. This is consistent with the properties of the cluster's brightest stars, which were resolved in the data for the first time. Finally, a numerical analysis of the galaxy's stellar content yields a roughly constant star formation rate of 1.3×10?3 M⊙ yr?1 and mean metallicity of Fe/H]=?1.3 dex from 15 Gyr ago to the present. |
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| Keywords: | galaxies: distances and redshifts galaxies: individual: UGC 4483 galaxies: irregular galaxies: stellar content |
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