Unanswered Questions
463 questions with no upvoted or accepted answers
14
votes
0answers
454 views
Terrestrial Exoplanet Skies – I've Built a Visual Sky Chart. Is it Accurate?
I'm an artist (and science enthusiast) and I've been trying to find a comprehensive resource that would help me clearly identify likely sky colors (as perceived by human vision) for exoplanets that ...
13
votes
0answers
402 views
Is it “weird” that all disc galaxies rotate once every billion years?
In a recent paper (Cosmic clocks: A Tight Radius - Velocity Relationship for
HI-Selected Galaxies by Meurer, et al.), it was noted in the conclusion that:
[This] implies a constant orbital time of ∼...
9
votes
2answers
303 views
Why is the track of the subgiant stage almost horizontal on the HR diagram?
It is stated that:
After the main sequence, as fusion weakens or stops in the core, outward radiation weakens. The helium core contracts and heats up. Gravitational energy is converted to thermal ...
9
votes
0answers
435 views
How to determine scalar-to-tensor ratio r from CMB polarization spectrum?
CMB polarization spectrum can tell us about the primordial scalar and tensor perturbation. By analyze B and E mode angular spectrum power spectrum and temperature power spectrum we can determine the ...
8
votes
0answers
46 views
How uniformly is cometary debris distributed along the entire orbit of the comet?
Meteor showers occur when Earth passes through debris shed by a comet (if I get that right). Does this mean that the entire orbit of the comet is strewn with debris? I suppose that the debris follows ...
8
votes
0answers
161 views
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 ...
8
votes
0answers
381 views
Horseshoe orbits and integration in C
I'm studying a particular case of the restricted three-body problem. It's been found that some objects follow a horseshoe orbit pattern, and I'm trying to sort out something through an integration ...
8
votes
0answers
93 views
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 ...
7
votes
0answers
127 views
How would astronomical seeing on Mars differ from that on Earth?
Astronomical seeing is the limiting factor for the resolution of all but the smallest Earthbound telescopes.
Source
Stunning advances in adaptive optics (along with it's predecessor speckle ...
7
votes
0answers
137 views
What fraction of a star's hydrogen store will be fused over its lifespan?
A main sequence star will fuse some of its hydrogen, but not all. In massive stars ($>1.5M_\odot$) the core is convective but the rest of the atmosphere radiative and hence does not mix much: as it ...
7
votes
0answers
175 views
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 ...
7
votes
0answers
82 views
Do mixed type remnant collisions produce anything interesting?
The recent detection of a binary neutron star inspiraling and colliding raises an interesting question in my mind. Type Ia supernovae are believed to be caused by white dwarf/regular star pairs and/or ...
7
votes
0answers
65 views
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 ...
7
votes
0answers
54 views
Has the Kepler data been examined for light curves due to phase changes of non-transitting hot Jupiters and other?
I found this article http://www.epj-conferences.org/articles/epjconf/pdf/2011/01/epjconf_ohp2010_03005.pdf from 2011 announcing that two dozen secondary eclipses of "hot Jupters" have been seen in ...
6
votes
0answers
92 views
What object in the universe is most opaque to neutrinos?
I had this thought, and my first guess was "high density = lots of absorption, so I guess it's neutron stars" but this physics.se question about that has a great answer which covers why that's ...
