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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Where are the Cepheid and RR Lyrae variable stars located on the H-R Diagram?
a. just above and to the right of B type stars b. just above and to the right of O type stars c. in the variable strip d. in the instability strip e. outside the H-R Diagram as missing items
From the Sun, the distance to the Galactic Center is about:
A) 8 pc. B) 8,000 pc. C) 100,000 pc. D) 225 million pc. E) 100 billion pc.
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
a. Any two rubber rods charged this way have opposite charges on them. b. Any two glass rods charged this way have opposite charges on them. c. A rubber rod and a glass rod charged this way have opposite charges on them. d. All rubber rods always have an excess of positive charge on them. e. All glass rods always have an excess of negative charge on them.
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