Double-Radio Sources, Quasars, and BL Lacertae Objects Are Now Considered

question 84

Multiple Choice

Double-radio sources, quasars, and BL Lacertae objects are now considered to be the same basic type of object-an accretion disk producing two oppositely directed jets-but they appear to observers to be very different because

• A) the relativistic particles ejected in the double jets are different in each case: electrons in double-radio sources, protons in quasars, and quarks in BL Lacertae objects.
• B) they are at different distances from Earth, so one sees more detail and different properties in those that are closer to Earth.
• C) they are of different ages.
• D) astronomers view them at different angles to the line of the double jets. Face-on to the accretion disk the source will look like a BL Lacertae object, edge-on as double-radio sources, and between these positions a quasar.

---

Definitions:

Holding Cost Rate

The percentage of the value of inventory held over a certain period of time as costs, including storage, insurance, and depreciation.

Economical

Characterized by efficiency and avoidance of waste, referring to the cost-effective allocation and use of resources.

Keiretsu

A closely linked alliance of businesses in Japan, often including manufacturers and suppliers, which cooperate to ensure mutual success.

Net Profit Margin

A financial metric that calculates the percentage of net profits earned with respect to sales revenue, indicating the efficiency of a company in converting sales into actual profits.