Mon. Not. R. Astron. Soc., 443, 1281-1290 (2014/September-2)
KK258, a new transition dwarf galaxy neighbouring the Local Group.
KARACHENTSEV I.D., MAKAROVA L.N., TULLY R.B., WU P.-F. and KNIAZEV A.Y.
Abstract (from CDS):
Here, we present observations with the Advanced Camera for Surveys on the Hubble Space Telescope of the nearby, transition-type dwarf galaxy KK258 = ESO468-020. We measure a distance of 2.23±0.05 Mpc using the Tip of Red Giant Branch method. We also detect Hα emission from this gas-poor dwarf transition galaxy at the velocity Vh = 92±5 or VLG = 150 km/s. With this distance and velocity, KK258 lies near the local Hubble flow locus with a peculiar velocity ∼ 3 km/s. We discuss the star formation history of KK258 derived from its colour-magnitude diagram. The specific star formation rate is estimated to be log[sSFR] = -2.64 and -2.84 (G/yr) from the FUV-flux and Hα-flux, respectively. KK258 has the absolute magnitude MB = -10.3 mag, the average surface brightness of 26.0mag/arcsec2 and the hydrogen mass log(MH I < 5.75 M☉. We compare KK258 with 29 other dTr- galaxies situated within 5 Mpc from us, and conclude that its properties are typical for transition dwarfs. However, KK258 resides 0.8 Mpc away from its significant neighbour, the Sdm galaxy NGC 55, and such a spatial isolation is unusual for the local transition dwarfs.
© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2014)
galaxies: distances and redshifts - galaxies: dwarf - galaxies: individual: KK258 - galaxies: stellar content
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