Unanswered Questions
170 questions with no upvoted or accepted answers
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Where can I find MITEoR 150 Mhz radio data?
I was working on the Aladin Sky Atlas v12 software and while working on the radio data, I came across this Radio sky survey that said MITEoR 150 MHz. Initially, I mistook it to be GMRT because GMRT ...
- 30.7k
2
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29
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Equation describing Energy Transport due to Radiation in the interiors of stars
I am considering a very elementary stellar structure and I'm required to derive an equation to describe the energy transport due to radiation. The answer I am supposed to obtain is:
$$\frac{dT}{dr}= -\...
- 779
2
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42
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"First gamma-ray eclipses from ‘spider’ star systems" - but have other types of gamma-ray eclipses been observed?
The January 28, 2023 NASA News item NASA’s Fermi Detects First Gamma-Ray Eclipses From ‘Spider’ Star Systems begins:
Scientists have discovered the first gamma-ray eclipses from a special type of ...
- 15k
2
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46
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How do I calculate the flux density of a substellar object?
I am currently trying to generate photometric passband colors for brown dwarfs and planets generated through MESA (Modules for Experiments in Stellar Astrophysics). I believe I understand the ...
- 61
2
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57
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The necessary conditions for driving winds with dust (Dust-driven Wind)
So lately I've read Intro to stellar winds (particularly chapter 7 Dust-driven winds) by Lamers & cassinelli, I forget how many times I've read this but I still don't really understand. So in the ...
- 123
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Where can I find definitions of minimum detectable flux sensitivity and signal to noise ratio?
I am struggling to find references that give precise definitions to these concepts. Even in PhD theses on the subject of gamma-ray astrophysics, for example, students do not define it precisely or ...
- 2,169
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Calculate the uncertainty in measured flux density from an integrated intensity map
I have some ALMA data, in the form of a spectral cube, which I have integrated along the velocity axis to create an integrated intensity ('moment 0') map.
The integrated intensity map shows emission ...
- 1,386
2
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357
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How to convert between surface density in JY/beam*KM/S / arcsec2 to mass surface density in Solar masses / pc2
I am interested in studying the gas kinematics of atomic hydrogen (21cm line) for a galaxy and have output I'd like to convert after assuming a model for my data using BBarolo.
...
- 1,111
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294
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Is it possible to make (or buy kit) DIY portable radio telescope that I can place on the balcony like optical telescope?
I want to have a small radio telescope to use on balcony instead of optical when sky is cloudy (it is very often).
Is it possible? What objects can be observed by that telescope? Is it possible to use ...
- 256
2
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33
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Is it possible to infer information about the structure of the universe beyond the observable one?
Is it possible to infer information about the structure of the universe beyond the observable one, by observing its effects on the parts we can see? Can for example gravity from sources we cannot see ...
- 2,522
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Farthest observed protoplanetary disk observed at radio frequencies? Catalog
This could be a naive question or maybe too easy to solve (I do not really know!).
Brief context: I'm interested in a certain planetary system at $d \sim 300 \, \mathrm{pc}$. It would be really nice ...
- 30.7k
2
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342
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Cosmology context plotting : Covariance matrix - Script to plot Omega_m vs Omega_Lambda diagram in Python
I have covariance matrices and Markov chains coming from the SCP (Supernova Cosmology Project) and I would like to plot all these data
in the particular diagram Omega_Lambda vs Omega_m or w vs Omega_m....
CommunityBot
- 1
2
votes
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answers
57
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What is the sun's maximum influence on a magnetic object?
How much magnetic repulsion could the sun's magnetic field produce on an magnetic object? Consider the object is ideal: It could be flat, to create more resistance, balanced, to stay on the opposing ...
- 6,300
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44
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Looking for analytical expression of Cosmic Variance - Poisson distribution?
I have an expression of Matter Angular power spectrum which can be computed numerically by a simple rectangular integration method (see below). I make appear in this expression the spectroscopic ...
CommunityBot
- 1
2
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0
answers
140
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Poisson noise for a squared contrast of density - expression of variance equal to $1/n^2$
I manage to compute the Poisson noise of a density field like this :
If I take $N$ the density of galaxies and compute the Shot noise with a Poisson distribution, I get :
$\langle N^2\rangle - \...
CommunityBot
- 1