38 Answered Questions for the topic astrophysics
What are the demographics of stars visible to the naked eye?
Of the stars that can be seen with the naked eye, what are the distributions of each type? For example, how many are main sequence? how many are Super Red giants/white dwarfs/neutron...
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06/08/19
Precision of spectroscopy for astronomy?
How precise can the measurements be when looking at spectral lines in astrophysics?For example, suppose I have a telescope in orbit, and I am looking at $H_\\alpha$ lines coming from a star at 613...
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06/05/19
How to explain the existence of heavier elements in Population I stars and in Population II stars contain lighter one?
Recently I read Astrophysics Notes where I found a statement that young stars are classified as Population I stars and relatively older one as Population II stars. Population I stars contain...
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How is it possible for astronomers to see something 13B light years away?
In a NPR News story from a few years back:> "A gamma-ray burst from about 13> billion light years away has become> the most distant object in the known> universe."I'm a layman when it...
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05/12/19
How would we see a near-lightspeed object emitting light?
Consider an object travelling near the speed of light relative to us (let it be a spaceship or a star), which is emitting light (consider it monochromatic resulting from a two level electronic...
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04/20/19
Recommend good book(s) about the "scientific method" as it relates to astronomy/astrophysics?
I am interested in astronomy/astrophysics, but I am not science major (I am a computer science graduate). Facts and results of the field are presented to the public without showing how these...
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What is the evidence for a supermassive black hole at the center of Milky Way?
Black holes cannot be seen because they do not emit visible light or any electromagnetic radiation. Then how do astronomers infer their existence? I think it's now almost established in the...
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In astronomy what phenomena have theory predicted before observations?
As far as I know, astronomy is generally an observational science. We see something and then try to explain why it is happening. The one exception that I know of is black holes: first it was...
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09/29/18
If at the formation of the Earth we had a rock with 1000 atoms of Potassium-40 inside, about how many Argon-40 atoms would be found in that rock today?
Potassium-40 decays to Argon-40 with a half-life of 1.25 billion years.
Multiple choice options
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1
25
100
250
500
999
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Astrophysics Astronomy
11/30/16
I am having trouble with this astronomy question
According to the present estimates, the Universe is about ______ years old.
A.14 × 107
B.14 × 109
C.14 × 105
D.14 × 1011
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09/13/16
Astrophysics question
Object A emits most strongly at 400 nm, while object B emits most strongly at 800 nm. What can we say about their relative temperatures?
A’s temperature is the same as B’s.Nothing. Temperature is...
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I have a physics/astronomy question
What’s a black hole? What’s the difference between a reflecting and refracting telescope?
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10/23/14
Schwarzschild black hole orbits spacecraft
A spacecraft is in a circular orbit around a schwarzschild black hole of mass M. a) find expressions for the orbital period as a function of r determined by an observer at rest at infinity and an...
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