Unanswered Questions
1,530 questions with no upvoted or accepted answers
16
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Planning to revisit Arthur Eddington's experiment from 1919
As the fateful day draws closer, the United States will host a celestial event that comes once in three generations. I plan to witness this first hand at the exact center of greatest eclipse.
In the ...
- 6,474
14
votes
0
answers
287
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How would a cooled down neutron star look when illuminated?
Assume we have a neutron star that has cooled down so far that it no longer emits visible light. If we illuminate it with a powerful external light source, what would it look like? Would it reflect ...
CommunityBot
- 1
13
votes
0
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307
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What is the limiting abundances of elements at the end of the stelliferous era?
Is there any reputable published source on expected elemental abundances at the end of the era of stellar fusion? I am here interested in the contents of galaxies; much of intergalactic gas will be ...
- 221
12
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188
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Estimating the tangential and cross component of the galaxy's shear using Gnomonic projection
I would like to know how I can estimate the tangential and cross component of the galaxy's shear using Gnomonic projection
of the right ascension and declination the galaxies relate to the center of ...
- 5,444
10
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180
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What 1° x 1° region is the optically darkest patch in the sky?
What 1° x 1° region of the night sky has the lowest flux of light?
(considering the typical visual/luminance filter range, approximations using other filters/bands are acceptable, but should be in the ...
10
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0
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158
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How well conserved is etendue in extreme gravitational lensing scenarios?
This excellent answer to Could dark matter exist in the Universe in the form of sufficiently dense objects? includes the following image and description:
Light from the background galaxy circles a ...
- 31k
10
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answers
160
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Water vapour in space
This question is inspired by, but different from, What happens if an ice cube is left in space?
Mark's accepted answer says "…if you stick your ice cube out in the Oort Cloud, it'll grow: the mean ...
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10
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114
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How can maser emission be unpolarized?
I was reading that:
However, unlike Galactic sources such as W3(OH), the emission is unpolarized and the 1667 MHz line is stronger than the 1665 MHz line.
but how is this possible? Does not the ...
- 201
9
votes
1
answer
409
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How many stars are in the Milky Way galaxy?
So, I've always heard that the Milky Way hosts between 100 billion to 400 billion stars.
My problem is very simple: I'm unable to find any research papers on that topic or giving those estimates. I'm ...
CommunityBot
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9
votes
0
answers
126
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Spatial wind speed distribution on Mars using dune shapes?
As a fan of exometeorology (the study of atmospheres of other planets), I scanned through a whitepaper Measuring Mars Atmospheric Winds from Orbit which says
Measurements of Mars
atmospheric winds ...
- 5,444
9
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0
answers
182
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Why would a black hole have a disk, but not emit x-rays?
There's a recent paper in Nature about LB-1, a B-class star orbiting a massive black hole.
I don't understand how these two parts of the paper can be reconciled. On page 2, the authors argue that the ...
- 132k
8
votes
0
answers
141
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What does the surface of a star with a radiative envelope look like?
This image from Wikipedia shows that main sequence stars above 1.5 solar masses have a convective core and a radiative envelope. The surface of our sun grainy because of convection cells right below ...
- 1,698
8
votes
0
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580
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Black spot in Mars' sky
There is a sequence of three raw images by Mars Curiosity Rover taken during Sol 3066 (22/03/2022, roughly) that show the same features of Mars' landscape and sky. They are separated by 38 seconds' ...
8
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123
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Color index B-V of the dimming Betelgeuse
Using AAVSO light curve generator I have plotted V and B magnitudes of Betelgeuse in the past 150 days to see trend of B-V color index. If dust would be the cause of the recent drop in the star ...
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8
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474
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What are the analysis steps in taking raw data from Kepler to a planetary system determination
I wish to get a concise list of the analysis steps required to take raw light data from a Kepler data set of a star through the steps needed to get to an analytical determination of the existence of a ...
- 221