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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What's the minimal argument I can give to reject The Geocentric Universe?
I'm new to Astrophysics, So pardon me if you find it silly to ask. I was just started reading about the basics of astrophysics. I read about the Greek Tradition, the concept of a geocentric universe. ...
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How much more mass would Mars need to currently have enough pressure for liquid water and oxygen?
My question is whether Mars just about failed to meet the threshold or missed it by a lot. It's been dry for 3 billion years. How much bigger would it have needed to be to buy it that extra time? Let'...
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Why did astronomers believe most or all stellar black holes had masses no greater than 15 solar masses?
The so-called 'mass gaps' for black holes, according to theoretical models, are between 2-5 solar masses and 50 to 150 solar masses. (Actually, I have read that there is no good theoretical reason ...
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How to determine the age of a star using asteroseismology?
I keep reading that a standard way to determine the age of a star is asteroseismology, and I tried to learn more about it. I am wondering if somebody could help me to describe the method in simple ...
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Keplerian Elements
So, I've been doing endless research, and I've found a bit of information, all in different places, that is. Now, I'm getting really confused about it; I can't keep up with it all anymore, so, now, it'...
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Is there software to calculate/plot decomposed rotation curves from observational data (FITS, etc)? [closed]
I have observation data of galaxies (in FITS format). From the FITS data, I want to calculate & plot the decomposed rotation curves as pictured below. Is there a software package that will do that ...
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How massive does a moon have to be to have a stable magnetic field?
Is there a minimum mass or other minimum properties necessary for a body to have a strong, stable dynamo to create a magnetic field conducive for life?
For example, would it be possible for Titan to ...
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Why isn't most hydrogen in the universe molecular (diatomic), instead of atomic (monoatomic)?
Similar questions have been asked before; but, why?
Is the monoatomic hydrogen left over from the Big Bang? And hasn't had the opportunity to collide with other hydrogen atoms yet?
Or are hydrogen ...
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What are detached black holes?
I understand what black holes are, and how they form, but I was recently introduced to the topic of detached black holes. What are they and how are they different from standard black holes?
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Can the energy transport by radiation occur in the convection region of a star?
I am new to stellar astrophysics and trying to understand the energy transports in the interior of stars.
Can the energy transport by radiation occur in the convection region of a star?
Here are my ...
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Has lunar opposition surge ever been observed from Earth? From Earth orbit?
This thorough answer to How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter? details observations of lunar opposition surge by the Clementine ...
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How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter?
Wikipedia's opposition surge is a short article and forwards shadow hiding and coherent backscattering as proposed mechanisms, but it doesn't really explain how much the brightness of the Moon ...
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Has anyone back-calculated previous close encounters between the Apophis asteroid and Earth?
The Apophis asteroid was only discovered in 2004, and shares an orbit similar to Earth's orbit, leading to many close encounters on the scale of decades.
Most of the stories about this asteroid are ...
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How do we know that spacetime is fabric? [closed]
I have started learning about astronomy as it amazes and inspires me.
I have a question. What led us to believe that spacetime is fabric? What is the evidence shows this, and is it considered proven?
...
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Spectrograph Arrangement, Noise, and Fourier Domain [closed]
If the transform of a line profile extends out to the Nyquist frequency such that we cannot see the noise level, what could we change in our spectrograph arrangement that would allow us to see the ...
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How can astronomers pinpoint the location of the source of a neutrino?
In the popular press, in recent months, we have heard a lot about high-energy neutrinos from far outside our solar system reaching our detectors....
But I wonder...
If a single neutrino from a great ...
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How much does the equivalent width of a line change by the introduction of 5% scattered light?
How much does the equivalent width of a line change by the introduction of 5% scattered light? We know the equivalent width is defined as $W = \int_{-\infty}^{\infty} \bigg(\frac{1-F_{\nu}}{F_c}\bigg) ...
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Why are CMB peak heights sensitive to the physical densities
A very simple question: why should it be that the CMB power spectrum allows constraints to be placed on the combination of parameters
$$\omega_c = \Omega_c h^2$$
$$\omega_b = \Omega_b h^2$$
as opposed ...
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What is sonic transition of an astrophysical fluid?
My notes mention sonic transition of a fluid. Is it where the speed of the fluid elements cross the speed of sound in the medium they are located?
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What are some challenging astrophysics problems for which we have data available? [closed]
I am a Computer Science student, and I would like to pursue a PhD in the same area, by applying artificial intelligence techniques to astrophysics. Not being an astrophysicist, however, I was curious ...
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How should I interpret this result obtained using lomb scargle?
I used lomb scargle for periodic analysis.
The time interval used is constant at 500 seconds.
#My data (x=time, y=intensity values) is :
x= (
00:28,
00:37,
00:45,
00:53,
01:02,
01:10,
01:19,
01:27,
...
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Why do M dwarfs emit more X-ray radiation than larger, more luminous stars?
I have read that "The relative amount of harmful radiation (to life as we know it) that stars emit can be 80 to 500 times more intense for M dwarfs relative to our Sun". Source This seems ...
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How do higher numbers affect orbital resonance?
When talking about orbital resonance, the most common resonances in our Solar System are 1:2 (think Jupiter's moons) and 2:3 (think Pluto and Neptune). However, the lack of larger numbers within these ...
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Why do massive rapid-rotating stars move bluewards off the zero-age main sequence (ZAMS)?
I'm reading a well-cited paper by Szecsi et al. 2015 titled "Low-metallicity massive single stars with rotation". The paper can be found here. I was surprised that figure 5 depicted an HRD ...
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Is it correct to say that only binary and solitary star systems are stable?
Recently it has been shown that a large number of binary stellar systems exist. It seems to me that the orbits of stars in systems containing three or more stars will inevitably be chaotic, resulting ...
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Is there a formula to calculate the angular speed at which the Sun apparently moves around the Earth?
Is there a formula for how to calculate the angular rate at which the Sun apparently moves around the Earth?
I know it takes 0.25 degrees/min, but as I understand it depends on other parameters as ...
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Pulsar signal periodicity detection algorithms?
I am currently working on pulsar signal periodicity detection. Most of the algorithm or paper which i read they use FFT (Fast Fourier Transform) and FFA (Fast Folding Algorithm ). Do we have any other ...
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How can astrophysicists discriminate between pp-chain solar neutrinos and CNO-cycle ones?
Astrophysicists at the Borexino experiment in Italy have recently claimed that they have detected CNO-cycle neutrinos coming from the Sun.
It was the Cover story for the November 26 issue of Nature.
I ...
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Anatomy of a galaxy cluster: understanding the relationship between dark matter halos and subhalos and galaxies within the clusters?
In my understanding, galaxy clusters contain dark matter halos, which in turn contain subhalos, and the subhalos are what surrounds individual galaxies. I know that is a simplified picture, but I am ...
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Why don't black holes quickly eat up the galaxy/universe?
It's my understanding that the radius of the event horizon of a black hole is proportional to it's mass.
Which means the surface area of a black hole is proportional to it's mass squared.
Lets just ...
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What is the mean distance of M53 Nucleus' stars ? (and other Globular Clusters) [duplicate]
Background: This Instagram post (from astronomypicturesdaily) tells that:
If our Sun were part of this star cluster, the night sky would glow like a jewel box of bright stars.
I opened this question ...
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Eccentricity of Exoplanets
The field of astrobiology specifically discovering other planets that revolve around the sun-like star (also known as Exoplanets) has risen since 1990, but certain orbits of exoplanets are observed to ...
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Radial Velocity Graph and Rossiter Mclaughlin Effect
I am trying to understand the effect of the Rossiter–McLaughlin effect on radial velocity plots. Can someone help me and explain what exactly is happening in the red circle?
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Earth and moon gravitational ratios and proportionalities
This question is for an astronomy class of mine. I don't believe the question is particularly difficult, but rather I'm having trouble understanding what it wants me to do. We haven't covered ratios ...
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What are some good books/online resources for astronomy problem sets?
I am currently studying for the international olympiad for astronomy and astrophysics (the syllabus can be found here: https://www.ioaastrophysics.org/syllabus/). I am currently using Carroll Ostlie's ...
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How do we differentiate between a star or planet and noise introduced due to equipment?
I understand that differentiating between celestial bodies and noise due to equipment is a fundamental problem in astronomy. I also understand that we solve this problem by looking at something called ...
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Is the age of the Universe really 13.8 billion years?
Ok, I know this has been asked by a lot of people, but my reason for asking this question is a bit different. Please read further.
I was watching a video by Fermilab (Start at 6:30, at 8:30 he ...
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Comparing Star Formation rate in different galaxies
I was looking for some scale to compare my result of star formation rate in order to find out whether it is moderate or high or low, but I couldn't find any scale. Is there any paper related to such ...
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The creation of comets
How are comet and meteors made, and what causes them to travel through space so fast? I have tried researching, but I decided this was the faster way.
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How to find the distance between two galaxies from ra and dec and redshift [duplicate]
I have ra and dec and corresponding redshift of galaxies. I would like to calculate the distance between two galaxies.
I did like this to find the nearest neighbour galaxies.
Suppose I am trying to ...
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Type II supernovae as a distance indicator
Could someone explain in brief exactly how type II supernovae could be used as distance indicators? as in simply the formulae used and how they are employed? I know there are certain methods based on ...
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What should be the "poles" for irregular shaped bodies?
Continuation of: What is the definition of a "pole" of a celestial body?
uhoh's answer says that distinct bodies should have a center of mass. If the body is spherical, then the COM will be ...
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What if a primordial black hole went through the Sun?
How much mass would the Sun lose to a primordial black hole that (initially) has 10 Earth masses, passing through or close to the center of the Sun at solar escape velocity? How massive would the Sun ...
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redshift in astrophysical plots [closed]
Why do astrophysicists often use redshift in plots? Why it is important to know how an astrophysical object evolves in function of redshift? I was seeing an "cosmological time per redshift ...
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Constants of three body problem(2 fixed centers)
I was solving two fixed centers problem and got answer in quadratures. After that i want to find constants of motion. First one is full energy - E. Second is $p_{\varphi}$. And third one comes from ...
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Was there ever a meteorite with a measurable gravity?
Did we ever find a meteorite (a meteoroid that has fallen down to Earth) whose mass, density and gravity were high enough to demonstrate their gravity similar to the Cavendish experiment, so that ...
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How does a planet-sized robot standing on a planet affect its gravity? [closed]
I originally asked this at the sci-fi exchange but was told it was off-topic as it was about real-world science.
Here is a picture of Unicron standing on top of the planet Cybertron, as written by ...
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Where can I find galaxy spectra (in the form of FITS files)?
I know there's SDSS and I tried searching for the spectra through the navigate and explore tool under CAS as well as by using RA/Dec coordinates under SAS, but every single time it comes out with 0 ...
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Why is a black hole's Hawking radiation temperature inversely proportional to its mass/size?
As a black hole shrinks in volume and mass, shouldn't its temperature get lower? Shouldn't it evaporate more slowly?
Naively, (very naively), I think that with a smaller surface area (as per its ...
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