The hydrogen lines in spectral type A stars a.are most narrow for supergiants. b.are most narrow for main-sequence stars. c.cannot be used to estimate the luminosity of the star. d.are very weak and difficult to see. e.are useful in determining the apparent magnitude of the star.

From the H-R diagram we know that hydrogen lines in spectral type A stars are most narrow for…

Answered: The hydrogen lines in spectral type A…

Similar questions

The average star spends what percentage of its life in the protostar stage? a. 0.1% b. 5% c. 10% d. 50% e. 90%
Based on what you know about main-sequence stars, select all of the correct statements from the following list. 1. Since the interiors of stars cannot be observed, there are no theories about their structure. 2. More massive stars are hotter and brighter. 3. The weight of a star must be balanced by internal pressure. 4. More massive stars live longer; they take longer to use up all their energy. 5. Stars change position on the main sequence throughout their lives. 6. Outward energy flow in a star is by conduction only.
A turnoff point corresponding to the youngest star cluster would occur at what spectral classification? a. B b. A c. F d. G
How high or low a star is on the main sequence is dictated primarily by ... Select one: A. its chemical composition B. the fraction of metals in its atmosphere C. what elements are fusing in its core D. the size of its photosphere E. its mass
Assume that when a certain main sequence star becomes a giant gas, its luminosity increases from L to 1000 L and its radius also increases from R to 1000 R. If the initial surface temperature is T, what approximately is the final surface temperature? A. 0.032 T B. 0.18 T C. 0.0010 T D. 0.010 T
This star has a mass of 3.3 MSun. What is the main sequence lifetime of this star? You may assume that the lifetime of the sun is 1010 yr.
Stars are born in a. reflection nebulae. b. dense molecular clouds. c. HII regions. d. the intercloud medium. e. the local bubble.
14 Suppose you see two main-sequence stars of the same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100. What can you conclude? (Neglect any effects that might be caused by interstellar dust and gas.) A B C D Star 1 is 10 times more distant than Star 2. The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2. Star 1 is 100 times nearer than Star 2. Star 1 is 100 times more distant than Star 2. E Without first knowing the distances to these stars, you cannot draw any conclusions about how their true luminosities compare to each other.
As2
Which of the following statements is wrong? A. A main-sequence star is cooler and brighter than it was as a protostar. B. Carbon fusion occurs in high-mass stars but not in low-mass stars because the cores of low-mass stars never contain significant amounts of carbon. C. when a main-sequence star exhausts its core hydrogen fuel supply, the core shrinks while the rest of the star expands. D. After a supernova explosion, the remains of the stellar core will be either a neutron star or a black hole.
1. Sirius A has an apparent magnitude of 4.72, determine its luminosity.
List the following 5 terms in order through a stars life cycle (starting with the sun), through the remainder of its lifetime: a. Black dwarf b. Planetary nebula c. Red giant d. Star (Sun) e. White dwarf

SEE MORE QUESTIONS

	a.	are most narrow for supergiants.
	b.	are most narrow for main-sequence stars.
	c.	cannot be used to estimate the luminosity of the star.
	d.	are very weak and difficult to see.
	e.	are useful in determining the apparent magnitude of the star.

The hydrogen lines in spectral type A stars a. are most narrow for supergiants. b. are most narrow for main-sequence stars. c. cannot be used to estimate the luminosity of the star. d. are very weak and difficult to see. e. are useful in determining the apparent magnitude of the star.