Unanswered Questions
292 questions with no upvoted or accepted answers
10
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0
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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 ...
- 30.7k
7
votes
0
answers
166
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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
votes
0
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76
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What effect do aircraft have on night-time visibility?
I have something of an interest in astronomy. I also have a 5" reflector telescope, plus of course binoculars. With the recent coronavirus emergency, a large number of commercial aircraft were ...
7
votes
0
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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
6
votes
0
answers
74
views
Recreating Observer Ecliptic Lat/Lon from JPL Horizons using SPICE toolkit
I apologise if this is the wrong place to ask. I am trying to recreate part of the calculations by the JPL Horizons system using SPICE. Specifically the Observer Ecliptic Latitude and Longitudes.
I'd ...
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6
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0
answers
349
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What would go into the design of a simple sky quality meter, used to measure night sky brightness?
@MCG's answer mentions several methods to classify night sky quality or brightness, and goes on to say:
Additionally, you could always purchase a SQM (Sky quality meter) which is a small, portable ...
- 30.7k
6
votes
0
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243
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Viewing "Diamond Fuji"
Diamond Fuji is a phenomenon in which the (typically) setting sun is positioned directly atop Mt Fuji. Some relatively detailed predictions for viewing times at a nearby park are available here.
I ...
- 161
6
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0
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69
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What is the reason for the dispute over the variation of core mass with heavy metal abundance?
In Metal-Poor Stars IV: The Evolution of Red Giants, Rood writes
The differences in the results of these papers are large enough to introduce appreciable uncertainties into the study of the ...
- 37.3k
6
votes
1
answer
189
views
Do narrow lines in the spectra of O- and B- type stars always indicate magnetic fields?
I was reading a paper on the differential emission measures of a set of hot O- and B- type stars. As the authors discuss in Section 3 (page 959), two stars, $\tau$ Sco and $\theta^1$ Ori C, have ...
CommunityBot
- 1
6
votes
1
answer
510
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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
5
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70
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Do all the accretion disks around a compact object (black hole or neutron star) emit astrophysical jet outflow?
Do all the accretion disks around a compact object (black hole or neutron star) emit astrophysical jet outflow? I mean is it mandatory for a jet to be emitted from an accretion disk?
If so, then why?
...
- 2,169
5
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0
answers
136
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What is this cluster of light trails captured on long exposure images?
I was taking photos of the Perseids meteor shower on 13/08/2022 in Peak District in the UK. The camera was fixed stably on a tripod, set on manual mode, taking 8-second exposures continuously.
When I ...
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5
votes
0
answers
69
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Type Ia supernova by fallback?
Is it possible for a massive star of more than 1.4 solar masses (probably around 3 or more but below the threshold for type II) to collapse into a white dwarf and a planetary nebula, then go supernova ...
- 6,684
5
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0
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79
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Obtaining the derived period of $\omega$ Canis Majoris
I have read these two papers:
On the nature of the Be phenomenon I. The case of ω Canis Majoris
Stellar and circumstellar activity of the Be star ω CMa
II. Periodic line-profile variability
In the ...
- 555
5
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0
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104
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Comparing Observing Techniques to Quantify the Effects of Starlink Satellites on Astronomical Observations
To take pictures of satellites I think I could use these methods listed below (are there more?)
Method 1
The satellites are tracked and their positions predicted. By utilising software tools and code ...
