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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Find Periodicity in Lightcurve Using Lombscargle Periodogram(Astropy)
How to find the Nyquist factor for unevenly sampled data like here.https://github.com/jakevdp/PracticalLombScargle/blob/master/figures/LINEAR_Example.ipynb ? I have time binned for 5 mins. I mean for ...
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What are the minimum variables that determines the orbital velocity of a planet?
I will try and be brief with this. I want to model a star system in a programming language. It has been a very long time since I did physics.
This says that planets have a speed given to them by the ...
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What would solar calculations look like in another system? [closed]
When you are determining things (area, luminosity, radius etc) in a star, there are certain things that involve our suns characteristics like solar mass and solar radii. Say I were in another system- ...
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Can magnetic monopoles only exist in a curved universe? [closed]
I’m trying to figure out rules for my Sci-fi universe and I need to know what type of universe, the universe needs to be for the existence of magnetic monopoles to exist. I read somewhere that the ...
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What's the modification of a parabolic trajectory when accounting for variation in gravity? [closed]
Everyone knows that if you fire a cannon, the cannon ball follows a parabolic trajectory. But that's in an unvarying gravitational field. What if the cannon ball flies so high that one must take the ...
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What is the 'AT' astronomical catalogue? And the 'TXS' one? As in AT2019dsg and AT2019fdr?
I cannot find a site stating what the AT or TXS star/astronomy catalogues are, even though some AT and TXS 'events' have been in the news lately....
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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....
user16492
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Was the Nobel prize for gravitational waves handed out based on a hand-drawn theoretical curve? Has the data been fit more rigorously now?
In Sabine Hossenfelder's November 2019 video "Have we really measured gravitational waves?" (transcript, video), Sabine mentions the now famous image of the generally agreed-upon-to-be-very-...
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Is the sound horizon 500 thousand light years or 500 million light years?
At 06:30 in the nice video Sound Waves from the Beginning of Time
about the baryon acoustic oscillations (BAO), the speaker says the sound horizon is about $500$ ...
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What is the meaning of integrated emission maps for these chemical species?
In the Astrobites article Spectral Line Survey Reveals New Molecules in Two Protoplanetary Disks integrated emission maps depict the spatial distribution of the flux received from each "line.&...
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Can earth grazers skip on the atmosphere more than once?
Earth grazing fireballs are asteroids that enter the atmosphere at a low angle, and skip off it, leaving to space again. Would it be possible that they skip more than once and still leave the ...
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Curated dataset of labelled images for NEO detection
I am looking for a dataset of images. Some images should contain NEO's (1 or more), others should not. With the dataset, there should also be an accompanying file, of which should contain 'labels'. ...
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What does lowercase 'beta' mean in this graph of radio-emitting galaxies?
Correlation between the mass of the galaxies (X-axis) and the difference of their radio emissions at different radio frequencies (Y-axis). Each symbol represents an individual galaxy. The image of an ...
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Procedure to construct a spectral energy distribution and bolometric light curve of supernovae?
Can anyone check the logic of this proposed workflow and/or point me in the direction of a guide and example to check my work?
Proposed procedure to construct a spectral energy distribution and ...
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Why does the 'Big Bang Nucleosynthesis' theory require that neutrinos, or at least sterile neutrinos, have a LARGE mass rather than a tiny one?
From Wikipedia, Sterile neutrino
Particles that possess the quantum numbers of sterile neutrinos and masses great enough such that they do not interfere with the current theory of Big Bang ...
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Are there any spectral lines with smaller frequencies than the hydrogen line?
The 21 centimeter hydrogen line originates from the hyperfine transition of neutral hydrogen. Are there any bigger wavelengths that originate from this method?
Radio emissions from rotating stellar ...
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Binning a Phase Folded Lightcurve
How do I bin a messy phase folded lightcurve? This is one of the phase folded generated plots for a variable star. I plotted the phase using the period extracted by Lomb-Scargle Periodogram algorithm. ...
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How long does the "eclipse" last on a space station at the L1 point between a moon and a planet last when the moon blocks the sun in front?
The situation I am asking about is as depicted in the picture. Supposing I have a space station staying perpetually at the L1 point, the moon will completely block the space station from all sunlight ...
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Where do Astronomers usually get their wavelengths? Where do they turn to look up standard, accepted values for spectral features?
When identifying isolated observed spectral features or fitting complex observed spectra or even running complex numerical simulations, one needs a reliable, standard table of known wavelengths and ...
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Do all C-O white dwarfs have more-or-less the same proportions of carbon and oxygen?
Type 1a supernovae are known for having very consistent energy yields, and they are caused when a carbon-oxygen white dwarf reaches the Chandrasekhar limit of about 1.4 solar masses. Since type 1a ...
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How is space a vacuum when there are planets, gases, etc?
Space has a lot of stuff so how can it be a vacuum?
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Why do some call the no-hair conjecture the no-hair theorem?
This excellent answer to Why would a black hole's magnetic hair being short-lived not violate the no-hair conjecture, but long-lived hair would? How long is “long-lived”? has got me thinking because ...
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Why would a black hole's magnetic hair being short-lived not violate the no-hair conjecture, but long-lived hair would? How long is "long-lived"?
Phys.org's Magnetic 'balding' of black holes saves general relativity prediction says:
There is a potentially hairy threat to the conjecture, though. Black holes can be born with a strong magnetic ...
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Is there a formula for a planet's orbit in a 3D space?
I'm trying to model the orbits of Earth and Mars and their positions at a given point in time. But I can only find 2D equations of elliptic orbits, which only contain the x and y variables. I have to ...
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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 ...
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Is a Hertz ratio to 65M ☉ proof that Betelgeuse had a core collapse in 1491 from a gravitational wave on January 14, 2020? [closed]
By analysis of gravity waves GW150914 to S200114f when compared to a ratio from the Black Hole merger of 65 M ☉ at 260 Hz with Betelgeuse frequency of 64.698303 Hz the gravitational release on January ...
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How can a black hole have a charge, or be charged?
So-called 'hairless' black holes (no-hair theory, or theorem?) , which is what real black holes are, can be described by just three characteristics: Mass, spin, and charge.
It is easy enough to ...
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What exactly is the orbital period value of Sirius binary star system?
My Textbook An Introduction to Modern Astrophysics 2nd edition (2017), page 557 mentions that the modern value is 49.9 years. But Wikipedia mentions 50.1284±0.0043 years.
Which is correct? Or, has the ...
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Learning astrophysics from zero
I'm a liberal arts student, an undergraduate English student who out of the blue, started getting interested in astronomy and physics, searching for facts all the time, googling about some theories, ...
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Error of bisector method
How to determine the error of bisector velocity span? I have found the article below, but I do not know what all quantities mean. What is the number of lines in the mask? How to find out x? How to ...
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Degrees of freedom in restricted circular coplanar three body problem
How many degrees of freedom does a mechanical system consisting of three bodies, the Sun, Jupiter and an asteroid, have in the restricted circular coplanar problem of the three bodies?
I know that if ...
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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 ...
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Role of power laws in astronomy?
I often see astronomers fitting data to power laws. What about power laws makes them so useful in astronomy? Why are so many astronomical observations well-fit by power laws? I know it's a relation ...
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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 ...
user16492
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Is the dark matter just regular matter out of the observable universe?
Could it be that darkmatter is actually the gravitational influence of regular matter that is situated out of the observable universe?
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Does black hole singularity really exists with respective to relative frame of reference? [duplicate]
How can one describe this phenomena?
What are the factors that we should consider for solving such a problem?
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How do astronomers know that distant galaxies aren't actually nearby star clusters?
When reading about the recent release of data from the Dark Energy Survey, and the 'pictures' of well over 200 million distant galaxies, I got to wondering:
How can they know that a small, faint, ...
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Basic, learning examples of applications of CFD and MHD in astrophysics, and current research directions using these techniques?
I am an undergraduate in Physics, and I have an opportunity to work with a some of my seniors to learn Computational Fluid Dynamics (CFD) and Magnetohydrodynamics (MHD).
I would like to choose my ...
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If Proxima Centauri goes supernova will it negatively affect the Earth? [duplicate]
Proxima Centauri is the closest star to the Earth (besides our Sun). If it went supernova, would such an event negatively affect the Earth? Can Proxima Centauri negatively affect the Earth in some ...
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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 - \...
user16492
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Can a neutron star ever be less than about 1.44 solar masses (the Chandrasekhar limit)? Why not?
I learned about the Chandrasekhar limit as being the UPPER limit, in terms of mass, for a white dwarf...
But, I have never heard of a neutron star being BELOW that mass, so I have wondered, recently, ...
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What new instruments "so sensitive that we can see (large circumgalactic winds) have only been on telescopes for a few years"?
The Rhodes College press release Prof. David Rupke and Team of Astrophysicists Make Major New Discovery About Galaxy Evolution links to
Astronomy Community/Nature.com: The Making of Makani; The story ...
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What is the application of pseudorandomness in astrophysics?
What are the advantages of using pseudorandom numbers in Monte Carlo simulation instead of random numbers? What are other applications of pseudorandomness in astrophysics? Many thanks.
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Any examples of a gas object temperature from Doppler broadening along one axis turning out to be wrong because velocity spread was not isotropic?
Discussions under Mass of the stellar cluster (not the whole galaxy) lead me to mention that when an actual temperature is inferred from a Doppler-broadened line profile (rather than just a linewidth ...
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Is **Voyager I’s** reduced data transmission rate as described in [this article][1] because of the distance or because its transmitter getting slower? [closed]
Is Voyager I’s reduced data transmission rate as described in this article because of the distance or because its transmitter getting older & slower?
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What exactly is space-time fabric?
I have heard about space-time fabric but I can't understand its definition. Is space-time fabric a physical thing or did Einstein imagine it to assist him with general relativity?
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Spectra: What is that Supposed to Mean?
I've found this website (click here for the link), the link leads you to a problem about the velocity Andromeda is going towards the Milky way galaxy, and you can try three approaches. I like to ...
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Virial ratio behaviour
I think I didn't understand something about virial theorem for an $N$-body system, for instance the behaviour of virial ratio $T/\Omega$, with $T$ kinetic energy and $\Omega$ gravitational potential ...
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Resource Recommendations to systematically develop a foundation via Self study in Astrophysics/Astronomy?
I am a high school senior (Grade 12) with a passion for Astronomy/Astrophysics. I already searched quite a bit here on the other questions on resources, but I couldn't find any that shows a concise, ...
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Astrophysical particle spectroscopy; narrow-line particle sources (charged or uncharged) for things other than photons? Have any been detected?
Is Cosmic Ray Astronomy a thing?
Is there an equivalent of the red shift effect for cosmic rays?
have got me thinking and under this answer I've commented:
That's a good point; there aren't as many ...
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