Irregular dwarf galaxy KK 230: A relatively young galaxy at the periphery of the local group?
Tóm tắt
We present some results of the photometric analysis of the stellar population of the irregular dwarf galaxy KK 230 on the basis of the archive database of the Hubble space telescope. The color index-magnitude diagram for KK 230 gets to magnitude 27
m
in the V and I bands, and it comprises stellar populations of various ages. The age of the youngest main-sequence stars is 3.2 × 107 yr. These stars are distributed along the north-south direction in the picture plane, and this fact can be linked to the observed kinematics of the neutral gas in the galaxy. Older blue and red supergiants are no less than 1.6 × 108 years old, and such an age implies that the star formation was episodic over the last several hundreds of millions of years. As judged from the position of the tip of the red giant branch, the distance modulus for KK 230 is m − M = 26.5
m
. The corresponding distance is D = 2 Mpc. Based on the average absolute magnitude M
I,RC and color index (V − I)I,RC of the red clump, we conclude that the majority of KK 230 stars have an age of no more than (2–3) × 109 yr, their metallicity being Z ≈ 0.0004.
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