Centaurus A is a radio galaxy that has a visible galaxy at the center. This central elliptical galaxy of Centaurus A is encircled by a ring of gas and dust, different from most elliptical galaxies. The dust ring orbits about an axis that is perpendicular to the axis of rotation of the elliptical galaxy. What does this suggest about this central elliptical galaxy of Centaurus A?
a. The radio jets have caused the dust disk to be driven around the elliptical galaxy.
b. There are at least two black holes at the center of the elliptical galaxy.
c. Centaurus A is probably the result of a merger of an elliptical galaxy and a spiral galaxy.
d. Dust is produced as the jets interact with the intergalactic medium.
e. Elliptical galaxies often contain dust that forms a disk along their rotation axis.
c
RATIONALE: Refer to ring galaxy.
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A) 8 pc. B) 8,000 pc. C) 100,000 pc. D) 225 million pc. E) 100 billion pc.
The coefficient of linear expansion of steel is 12 × 10-6K-1. What is the change in length of a 25-m steel bridge span when it undergoes a temperature change of 40 K?
A) 1.2 cm B) 1.4 cm C) 1.6 cm D) 1.8 cm E) 2.0 cm
Where are the Cepheid and RR Lyrae variable stars located on the H-R Diagram?
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Rubber rods charged by rubbing with cat fur repel each other. Glass rods charged by rubbing with silk repel each other. A rubber rod and a glass rod charged respectively as above attract each other. A possible explanation is that
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