IC 4970

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IC 4970 is an unbarred lenticular galaxy in the constellation Pavo, about 212 million light-years away. It is interacting with its much larger neighbor, the barred spiral galaxy NGC 6872, and the two galaxies are close together as they orbit each other. Computer simulations suggest that IC 4970 passed nearly along the plane of NGC 6872’s disk, with the closest approach about 130 million years ago. This encounter helped shape NGC 6872 into its current long, stretched form.

Studies using ultraviolet to infrared data show that the interaction triggered significant star formation in NGC 6872’s northeastern and southwestern arms, starting around 130 thousand light-years from its center. A bright ultraviolet source at the end of the northeastern arm, about 290 thousand light-years from the nucleus, may be a tidal dwarf galaxy formed by the interaction. The stars there appear to be younger than about 200 million years, consistent with the timing of the collision.

IC 4970 itself is roughly 150,000 light-years across and has several alternate designations, including ESO 73-33 and LEDA 64415. It was discovered on September 21, 1900, by American astronomer DeLisle Stewart.