Английская Википедия:DDO 44
Шаблон:Short description Шаблон:Infobox galaxy DDO 44 (or UGCA 133) is a dwarf spheroidal galaxy in the M81 Group, believed to be a satellite galaxy of the nearby NGC 2403.
Structure
DDO 44 is a relatively large dwarf galaxy, and it has been observed to possess a tidal tail extending at least 50,000 parsecs from its center.Шаблон:Sfn It has an estimated metallicity ([Fe/H]) of -1.54 ± 0.14.Шаблон:Sfn Due to its proximity and relative velocity to the larger NGC 2403, it is believed to be NGC 2403's satellite galaxy.Шаблон:Sfn Stellar streams has been observed to originate from DDO 44, flowing towards and away for NGC 2403, indicating tidal disruptions.Шаблон:Sfn Around 20 percent of the galaxy's stars are believed to be of intermediate age (between 2-8 Gya),Шаблон:Sfn with the most recent stellar formation being estimated at 300 Mya due to a lack of young bright blue stars.Шаблон:Sfn This lack of bright stars caused DDO 44 to have a relatively low level of brightness.Шаблон:Sfn
It is located approximately 3 million parsecs away from the Milky Way,Шаблон:SfnШаблон:Sfn and 79 arcminutes towards north-northwest from NGC 2403 (or approximately 75 kpc).Шаблон:SfnШаблон:Sfn Mass estimates based on luminosity measurements give a galactic mass of 2×107–6×107 M☉.Шаблон:Sfn This makes DDO 44 by far NGC 2403's most massive known satellite galaxy, with the other known satellite galaxy (MADCASH J074238+652501-dw) having a mass of just ~105 M☉.Шаблон:Sfn HI observations place an upper limit for DDO 44's hydrogen gas mass at 4×105 M☉.Шаблон:Sfn
References
Bibliography
Шаблон:Camelopardalis Шаблон:Sky
