Unanswered Questions
401 questions with no upvoted or accepted answers
10
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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 ...
- 30.3k
10
votes
0
answers
140
views
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 ...
- 5,636
10
votes
0
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509
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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 ...
- 1
8
votes
0
answers
237
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Is there a standard deconvolution procedure to remove JWST's diffraction pattern yet? If so, would Arp 220 be a good candidate on which to try it?
Source: Webb captures the spectacular galactic merger Arp 220
Shining like a brilliant beacon amidst a sea of galaxies, Arp 220 lights up the night sky in this view from the NASA/ESA/CSA James Webb ...
- 30.3k
7
votes
0
answers
157
views
Can terrestrial infrared telescopes see through clouds or haze, sometimes at least?
My answer to Could UV-A imaging sensor reasonably see a total eclipse in progress through clouds? suggests that while clouds blocking visible light observation of the (partially) eclipsed solar disk ...
- 30.3k
7
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0
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166
views
Angular resolution of naked eye at night; type of vision used
It appears that most sources quote the angular resolution of the eye as 1', regardless of day and night.
For instance,
Naked eye
Seconds of Arc and the Unaided Eye
However, the following websites give ...
- 2,349
7
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0
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214
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What's the largest angle that light has been "seen to bend" by gravity? (of one object by a separate object)
Gravitational lensing is everywhere! because it falls off so slowly with $r$:
$$\Delta \phi \approx \frac{4GM}{c^2r_0}.$$
That's the first order term. For a nice derivation see Viktor Toth's The ...
- 30.3k
7
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0
answers
256
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Get the expression of probed volume between 2 redshifts
1) I can't manage to find/justify the relation (1) below, from the common relation (2) of a volume.
2) It seems the variable r is actually the comoving distance and not comoving coordinates (with ...
CommunityBot
- 1
7
votes
0
answers
2k
views
How to calculate the temperature of an exoplanet?
I was given an exoplanet similar in size and distance to host star to our own earth. It's orbiting a star with luminosity six times our sun, the greenhouse coefficient 0.3, bond albedo 0.3.
I would ...
- 5,636
6
votes
0
answers
153
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How was the axial tilt of planets measured?
https://en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies gives the axial tilt of all planets with two decimal precision, but how and when were they measured so precisely ?
I guess it's "easy&...
- 30.3k
6
votes
0
answers
206
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How far have stars been seen beyond the center of the Milky Way?
What lies near the center of the galaxy is of great interest and in recent times the motion of dozen(s) of stars at the center of our galaxy orbiting around Sgr A* have been measured in great detail. ...
- 30.3k
6
votes
1
answer
510
views
Could non-supernova carbon, oxygen, or silicon flashes be observed?
I was reading about the helium flash, the short but sudden onset of helium fusion in certain red giant stars. As I understand, the upper (nondegenerate) layers of the star absorb the energy as they ...
- 5,336
6
votes
1
answer
217
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Could an ultra-hot Jupiter flare?
Some of the ultra-hot Jupiters (WASP-33b, KELT-9b) have dayside surface temperatures similar to low-mass stars. Would they be capable of producing flares? To be specific, I am asking about the ...
- 16.3k
5
votes
0
answers
88
views
Is there a noob-friendly website/app for tracking a astronomical body's apparent movement over time?
As I walk home along my road most nights in winter, I see the Moon and one-or-more planets.
Unsurprisingly, over the last 2 months, if it's been the same planet and it (and the Moon) has been in ...
- 338
5
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513
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How far away must galaxies be before current telescopes can no longer measure how quickly they are rotating around one another or internally?
What is the distance limit and does it depend on the size of the galaxy and on noise and interference from gas clouds and our own Milky Way?
- 38.9k