Unanswered Questions
127 questions with no upvoted or accepted answers
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How to write a normalized, dimensionless form of Binet's relativistic equation?
$$\frac{\delta^2 u}{\delta \theta^2} + u = \frac{\mu}{h^2} + 3 \mu u^2$$
This is Binet's relativistic equation. Here $u = 1/r$ where $r$ is the radial distance, and $\mu$ is the reduced mass of the ...
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A high-temperature isolated neutron star could be super-Eddington?
If the surface temperature of a young neutron star is hot enough, say, several KeV, its blackbody radiation could be super-Eddington?
Did any paper discuss this scenario before?
- 3,137
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What are the procedures and protocols to use with Gauss'method and personal observations?
I would like to use the Gauss' method to determine the orbit of planets of solar system.
I would like to calculate their orbits with personal observations.
What is the methodology/procedure/protocol ...
- 300
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What's the profound reason(s) why the star formation rate drives the scatter of the mass-metallicity relation in galaxies?
Since decades it's well known that a correlation between stellar mass and metallicity (Z; both stellar and gas-phase Z, but here I focus on the gas-phase Z) exists (e.g., Tremonti+04; analysis of >...
CommunityBot
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What is known about the angular momentum distribution within galaxy clusters?
I recently saw a 3D-plot of proper motions of galaxies within the Laniakea super-cluster (https://sketchfab.com/models/754cb85550fb42588175f8a215718521). Is a similar 3D map of the vector field of ...
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Question about finding energy density of a fermionic-bosonic gas
We know that energy density is given by this formula:
$$u = \frac{1}{V}\int_0^\infty\epsilon_pf(\epsilon_p) g_s V/h^3 4\pi p^2 dp$$
Where $\epsilon_p=pc$ for relativistic particles. also $f(\...
- 15k
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Why does the axial tilt & the rotation speed of Saturn & Jupiter vary so much?
I have seen Jupiter and its 4 largest moons in a telescope, several times. The moons are always aligned in a line. This is fine. Very interesting. But.. in case of Saturn, not only that we can see its ...
- 126k
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cross-matched SDSS-WISE catalog
Please where can I find cross-matched SDSS and WISE dataset for a machine learning project?
(Galaxy-star-qso classification task)
1
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Fourier transform of the density fluctuation
There is a Fourier transform that I don't really understand in my textbook (p.218).
I have the following equation:
$$\ddot{\delta} + 2H\dot{\delta} -\frac{3}{2} \Omega_m H^2 \delta = 0
$$
Then using ...
- 101
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Determining Time Based on Arc Seconds
So our arc day starts at 20°41'32 which is midnight (0:00) and ends 24 hours later at 21°42'42. According to my calculations it traveled 0 degrees, 59 minutes, and 30 seconds or 3570 arc seconds in 24 ...
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Question about the core mass fraction of planets and its relation to the magnetic field
I have a question about planetary cores and their relation to the magnetic field.
Around how massive (using this in the sense of mass, not size, for clarity) does a core need to be in relation to the ...
- 376
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What would be the new Equation of motion if the magnetic field's origin is shifted from the origin of a co-rotating spherical polar coordinates?
The equation of motions due to the dipole magnetic force of a planet in a frame corotating with the planet and origin at the centre of planet assumed to be sphere components wise are given as below:
\...
- 145
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What is value of charge by mass ratio (q/m) for a spherical micro charged particle with surface potential 6 volts in S.I units and in e/amu units?
In Liu and Ip (2014),The Astrophysical Journal, 786:34 (8pp), the value of q/m is derived as follows :
"for a dust grain with radius 'a', from $\phi = \frac{4\pi q}{\varepsilon_0 a}$ we have $\...
- 145
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Formula for "gravity assist"
I am familiar with the concept of "gravity assist" by which a space probe or other object, passing near a moving planet, can pick up some of the planet's orbital velocity.
I presume that ...
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Is there such a thing as a map that shows the current (not observed) positions of celestial objects?
As I understand it, maps of the sky and three-dimensional maps of the universe all show the observed positions of celestial objects.
Are there any maps that show our best guess at their current ...
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