Questions tagged [astrophysics]
Questions involving the physics of the universe, especially the nature of astronomical objects, energy fields, and/or regions, rather than their positions or motions in space.
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Conversion of 1D plot in 3D plot gives different physics
I am to track the path of a particle due to Lorentz force of the planet magnetic field, assuming there is no gravitational force on it.
The equation of motion due to Lorentz force in rotating ...
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Would impacting plasma clouds destroy electronics on Earth or make them only temporarily inactive?
We read that solar flares have increased again recently. At the same time, it is always reported that the plasma clouds hitting the Earth would, under certain conditions, disable all electronics on ...
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Geocentric Planetary Configurations
An asteroid is orbiting the Sun in a circular orbit of radius 4AU. Calculate the ratio of its angular diameters at opposition and quadrature.
I have tried using the idea of elongation but it does not ...
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"And in some cases, a (free floating) planet (FFP) can form on its own outside of any solar system." Cool! But what are those cases?
The April 2, 2023 Inverse article 9 Years Ago, Astronomers Found Two Rogue Planets — But They Didn’t Realize It Until Now says:
Planets are typically part of a planetary system and are ...
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Formation of a non-Sol Oort cloud with high mass planets
Based on recent developments in astronomy, pertaining to a greater degree of measurement, the mass of the Oort cloud around Sol is apparently only about 1.5 times the mass of earth,in contrast to over ...
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Are more stars or more galaxies cataloged, currently, and how has the ratio evolved over time?
I recall that there are of order 100 billion stars in a galaxy and 100 billion galaxies in the (observable) universe, or something roughly like that.
Since we are IN a galaxy we have an opportunity to ...
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What do the symbols signify in Dr. Becky Smethurst's radiation pressure equation for black holes?
In her most recent video, "An ULTRAMASSIVE black hole has been discovered in a BRAND NEW way!", as well as a previous video, "How massive can black holes get?", Dr. Becky Smethurst ...
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Have we discovered a Galaxy lacking in Dark matter?
This question is relevant but it was speaking about a specific discovery reported by pieter van Dokkum, and the answer then mentioned it was disputed whether the paper's conclusion is even correct.
I ...
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What exactly IS a "Domain Wall"?
A Domain Wall is an "topological defect" and a 2-dimensional singularity. They are widely theorized to exist throughout the universe, but none have been detected yet. I'm having trouble ...
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Do brown dwarf 'stars' fuse simple hydrogen (p-p reaction) at all?
I sometimes read that only deuterium-deuterium fusion can occur in brown dwarfs... And maybe deuterium-proton fusion? To He-3?
In order to overcome Coulombic repulsion and, occasionally, fuse, protons ...
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Stellar structure equations - mass continuity
Out of the four stellar structure ODEs, I would like to understand why the mass continuity equation was named this way. It reads
$$ \frac{dm}{dr}=4\pi r^2\rho \tag{1} $$
and I understand what it means,...
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How can I get a list of the closest x stars and their distances from the Gaia ESA Archive using Python?
I've been trying to find this out for a while now, but I'm making zero progress. I really struggle to find good documentation for the query language, and even in the astroquery library I can't find ...
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Numerical Programming using ODEINT takes more than 17 minutes
I am trying to track the trajectories of a charged particles under the influence of Gravitational and Electromagnetic effect. Computing for time points, t0=0second -tf= (36002430)sec with stepsize 0....
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Motion equation of a space engine in low-earth orbit
My goal is to simulate the movement/motion of a space capsule from low-Earth orbit with initial conditions emulating an initial thrust. Here is the code, Is it right? I know that the next step is to ...
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Why are the largest stars, such as O-type or B-type, most likely to be in multi-star systems; while red dwarfs are least likely?
I was just reading about what percentage of stars in our galaxy and, perhaps, other galaxies are in binary systems (or trinary... etc.).
Researchers keep going back and forth about whether or not most ...
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If the Universe has a positive curvature and a closed spatial geometry, does it therefore have a finite volume and a geometric center?
Based on the recent Planck Legacy 2018 release confirming the presence of an enhanced lensing amplitude in the
cosmic microwave background (CMB) power spectra compared to that predicted by the ...
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Abundance of an element Xi in mass fraction from its abundance by number
How can I calculate the expression of the abundance of a given element Xi in mass fraction from its abundance by number Ni/NH, where log(NH) = 12 is the abundance by number of hydrogen?
I've tried the ...
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Can the curvature of a closed universe be measured?
Suppose we were in a closed universe likened with a spherical surface such as that of the Earth's surface.
Assume also that the limits, represented by the limits of the observable universe, ...
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How to get the right ascension of the Moon?
Is there any approximate way to calculate the right ascension of the Moon? I already got declination but still, need the right ascension to calculate the final position of the moon. Thanks for all ...
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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}= -\...
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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 ...
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How does the entropy diffusivity changes with radius in the Sun?
Could you please explain - How does the entropy diffusivity changes with radius in the Sun?
As far I know, In the convection zone, the entropy diffusivity increases as the temperature and density ...
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what does it mean to have momentum suppressed cross section
What does it mean to have momentum suppressed cross section and zero momentum transference in direct and indirect detection of dark matter
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A silicate asteroid hits the Moon at 35 km/s. What portion of the ejecta generated reaches lunar escape velocity?
Background:
Below is a graph from John D. O'Keefe's and Thomas J. Ahrens's Impact and Explosion Crater Ejecta, Fragment Size, and Velocity. Said graph models the amount of ejecta produced by silicate ...
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How to call the fear of no gravity? [closed]
In opposite to barophobia I can't google out a fear of the case, when a man is taken out of the ship and he must go through the spaceship's docks and he can't get the direction of gravity - in the ...
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Are red giants still primarily made of hydrogen? What is their exact composition?
How much lower is the ratio of hydrogen to helium in a red giant vs a 'normal' main sequence star like our Sun?
Also, how low does the ratio get at the end of a red giant's life? (Just before it ...
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The path of a particle in planet's magnetic field doesn't not seem to change with the charge of the particle. Can someone please check what is wrong?
I am trying to plot the path of a charged particle in a planet's magnetic field. For positive and negative charge (β=charge/mass) different solutions/paths are expected. But,I got the same solution (...
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What determines how accurate a particular method is at finding the period between Lomb-Scargle and String Length Minimization?
I've been using the Lomb-Scargle and String Length Minimization methods to find the periods of various astronomical objects with unevenly spaced data. I wanted to see if I could find any patterns ...
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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?
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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 ...
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Potential energy in an expanding universe
A question you wonderful geniuses can hopefully answer. Imagine a piece of string drawn between two galaxies. Space between the galaxies is expanding. What force is being applied to the string? Where ...
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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 ...
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Time and space travel as applied to expanding space and the ratio of/between time and distance
If a place is 500 light years away, then I set out to this place, then is it true to say that, the place which I set out from, will be 750 light years away from my destination, once I have reached it?
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Deviations of conservation laws in the context of cosmological evolution?
If energy is "not conserved" in General Relativity (or at least, it is difficult to define it) in the context of an accelerating expanding spacetime (like it happens in our Universe), are ...
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Calculate how far we could see through Earth's atmosphere if it had the opacity of the solar photosphere?
I've newly started studying astrophysics. There is a question in the book "An introduction to modern astrophysics" by W. Carroll: Calculate how far we could see through Earth's atmosphere if ...
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What actually are line-driven winds?
I have read several books (viz. intro to stellar winds)/articles about stellar winds (dust-driven, line-driven, coronal winds), but still didn't understand the explanation. I understand that line-...
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Can we affect an object that's already passed beyond the Hubble volume, and if so, why?
This paper by Toby Ord states this: "There is substantial confusion about how to interpret the Hubble volume, with widespread erroneous claims that we could never affect (or see) galaxies beyond ...
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How can we practically measure the perihelion/aphelion of a solar system planet from scratch?
I've searched online for an answer, but they all seem to require other parameters (e.g, eccentricity and semi major axis) to be able to mathematically solve for the perihelion/aphelion. If we don't ...
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Do these results mean that I have found this exoplanet?
Yesterday I was going through the TESS mission data on mast portal and after applying some filters I found some data. I started analyzing that data using the lightkurve library.
plot without using the ...
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Since there is an axial tilt present on planets, does this also affect their orbital angular momentum?
I would like to know whether an axial tilt on planets will affect their orbital angular momentum since I am creating a homework regarding angular momenta of planetary bodies in the Solar System.
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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 ...
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How to look up "all things astrophysical" about A=9 (or other light isobars)?
All the light isobars (group with same atomic number mass) are interesting and quirky, but let's use A=9 as an example. 9C and 9Li beta decay to particle unbound states in 9B and 9Be (except to 9Be's ...
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Cosmic microwave background the same as the first visible light at 379,000 yrs after the Big Bang? How do these measure the age of the universe?
Was the CMB emitted at the same time as visible light at 379,000 yrs after the BB ? Was this a one time event ? If headed away from us, how does it measure the age of the universe?
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Distance of distant galaxies
Can two galaxies, one with a redshift of 7 and the other a redshift of 8 have the same angular distance (distance from the Earth during the emission of the observed photons)?
If not why ?
Example: ...
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How long would it take a rigid rod from Earth to the Sun to move if pushed?
They would say, of course, that because nothing can be allowed to transmit faster than light, it would take 8.20 minutes for the fellow at the other end of the rod to feel the push.
But wouldn't the ...
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Do all black holes, including stellar-mass ones, rotate at nearly the speed of light? Also, what exactly does that do to their shape?
From what I understand, astrophysicists have known for almost a decade that supermassive black holes seem to spin at incredible velocities; nearly the speed of light... In fact, some of the outer ...
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Is Dark Matter possible if there is dynamical friction?
If dark matter existed: wouldn't it slow down the orbital velocity of stars in galactic disks by dynamical friction more than it would accelerate them through additional mass? The original orbital ...
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Initial state for a 3-body problem to create Figure 8 [ restricted to 2D ]
I've made an n-body simulation solution using the naive algorithm of O(n^2) in my library ChelseaaJS.
I was trying to make some pleasing 3 Body simulations.
I wanna do the 8 figure thing.
I know it's ...
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What is Gravitational softening length?
I was reading the Aquarius simulation preprint (Springel et al. 2008) The Aquarius Project: the subhalos of galactic halos as a reference for my internship. I came across the term Gravitational ...
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How to understand the charge of a black hole [duplicate]
How can I understand the charge of a black hole?
We can understand the charge of elementary particles, like the charge of a proton or neutron. But what does the charge of a big object like that of a ...
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