Questions tagged [astronomy]
The science dealing with objects and phenomena located beyond Earth. In particular, this applies to observations and data. At its core, astronomy is the physically informed cataloging and classifying of the contents of the universe in order to better understand what is out there.
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Has the curvature of space from GR ever been validated? [duplicate]
It is my understanding that at low gravitational potentials like we experience on earth that the time curvature dominates and that the curvature of space only becomes relevant within stronger ...
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Are astronomicaly aberration compensated images of galaxies noticeably different from regular galaxy images?
Are astronomical aberration compensated images of galaxies noticeably different from regular galaxy images? How do they then differ? Their arms would be less curved.
I am not talking about the ...
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Dwarf galaxy rotation speed around Andromeda/Mily way
We know that the rotation speed of stars around the center of a galaxy is roughly flat.
But how fast does the dwarf galaxy rotate around the bigger galaxy, say andromeda or milky way?
Do they also ...
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Is this scientifically useful exoplanet transit data? [closed]
For a physics project, I am trying to derive properties of exoplanets through their transit light curve. I tried to get the data myself, on the known exoplanet Qatar-6b.
My Equipment:
8" Newt. ...
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Is the temperature of the hottest star's core known?
WR 102 is believed to be the hottest star in the observable universe, whose surface temperature is $210,000 ^\circ K$. But the related wikipedia entry does not say anything about the temperature of ...
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Did the Double Asteroid Redirection Test (DART) trigger an answer for the Fermi paradox? [closed]
The successful implementation of the Double Asteroid Redirection Test (DART - https://en.wikipedia.org/wiki/Double_Asteroid_Redirection_Test) was an awesome feat of engineering.
However, ...
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Can a beam splitter be used to measure Earth's absolute motion through space?
Let say the Earth is not moving through space...Then a beam splitter that refracts the beam into 2 new created beams at an angle of 90° towards reflectors which will reflect the beams at 180° again ...
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Stellar classification: Luminosity class
So in the astrophysics textbook by Carrol and Ostlie, when the luminosity class is discussed, it has such a sentence "The ratio of the strengths of two closely spaced lines is often employed to ...
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Keck versus Webb: discrepancies in the redshift measurements of the galaxy GN-z11 (the most distant galaxy discovered with the Hubble Space Telescope)
Two years ago Nature Astronomy published a paper based on measurements from the Keck Telescope stating that the redshift of the galaxy GN-z11 (discovered by Hubble) is:
$$ z=10.957 \pm 0.001 $$
Source:...
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How does Viscosity of the Sun varies as we go from core to the convective zone?
How does Viscosity of the Sun varies with its radius?
For. eg, Here is the graph of the Density of the sun v/s radius. I am looking for the Viscosity v/s radius plot.
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Is it possible to tell the difference between a young star that is just "big" and an older red giant?
I read the Wikipedia page for one of the biggest known stars, UY Scuti, and was curious to see the age of the star isn't really known at all.
When a star's hydrogen fuel is exhausted, it starts ...
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Given the gravitational lens, how do we actually know where stars/galaxies are actually located?
Hobby physics newbie at best...
Given that we know that gravitation bends light and we even use that to phenomenon to observe distant stars (gravitational lens). How do we actually know where a ...
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What are astrocentric co-ordinates?
A program I am using requires the ecliptic astrocentric cartesian coordinates of the Earth and the Sun in AU however I have never come across these co-ordinates before and the internet doesn't provide ...
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A sense in which inverse square law forces are scale invariant?
For a fixed separation, the gravitational acceleration between two uniform spheres of density $\rho$ is proportional to their radius $r$. But since angular sizes and distances across the celestial ...
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Observed flux of a non-spherical object
I recently had an exercise for which I had to find the observed flux of an annulus (accretion disc of a black hole). With the assumption that the annulus behaves as a perfect black body, the provided ...
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Temperature estimate from eclipsing binary
So assuming perfect edge on eclipsing binary, we can estimate the temperature ratio of the two stars because the "blocked area" is the same, and thus the amount of light "dimmed" ...
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If we had just invented the first clock, and we only had a calendar system, how would we set the time of day for the first time?
I've noticed there are extensive answers on this website about the accuracy of atomic clocks and how they reference the time between each other with the average of time between each other, but I ...
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Identifying the Milky Way uniquely [closed]
Let’s suppose you wanted to elegantly represent the Milky Way in a minimalist fashion in a way that would make sense a billion years hence (ie let’s set aside the damage wrought by colliding with ...
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If you had an indestructible disk, where would you place it to block the most energy from the sun? [closed]
Imagine you have an indestructible, opaque disk, (say 100m in diameter), and you want to place it between the sun and the earth to block the most energy from hitting the earth.
Some assumptions:
We ...
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Why is mercury the closest planet to the Sun? [closed]
I just want a solid reasoning that why Mercury is the first planet away from the Sun, then Venus, then Earth, then Mars and so on.
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How are poles and equators geometrically defined in a 3D matrix (curved space) that is a part of a 4D matrix (hyperspace)?
Our planet's surface is a curved 2D that has an infinite number of equators although we chose just one for vital geom. orientation purposes. Every of those equators has its 2 conjugate poles that can ...
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Emissions in the gamma ray frequency from gamma ray burst [closed]
Since almost all the emissions detected from gamma-ray burst are from its afterglow which are not in the gamma-ray frequency. Is the afterglow emission frequency lower than gamma-ray frequency ? I ...
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Introductory books on astrophysics [duplicate]
I'm looking to get deeper into astrophysics and physics in general. I already know physics from the internet (YouTube physics channels, etc.). I don't have a lot of mathematical skills. I know some ...
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Has anybody measured the Schwarzschild radius of a black hole and does the radius equal the radius predicted from the mass?
Have schwarzschild radii been measured from quasars or lensing black holes of known mass?
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Observational status of Sciama's hypothesis
I have always taken the existence of inertia more or less for granted, as an observational fact that does not require explanation.
But on reflection this is an unscientific attitude, and perhaps there ...
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Database for galaxy luminosity (or mass) distribution
I'm trying to get data on luminosity (or mass) distribution for galaxies.
I came across one paper (https://arxiv.org/abs/1106.3564) which gives luminosity distribution for Andromeda.
But is there any ...
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Does only the space region movement due universe expansion affect the possibility of viewing a star?
My question is maybe simple and easy to answer because the intrinsic speed of the star affects only the final frequency of observed light but are there any tricks about the combination of object ...
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How do you actually use an astronomical interferometer to measure small distances?
The question in the title might be too broad, so for definiteness we can focus on the Michelson stellar interferometer which, as I understand it, is more or less just two telescopes some distance ...
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Resolution: Telescopes vs. Camera Objectives
Telescopes and Camera Objectives are both optical systems which image objects from far away to a finite image distance. Although camera objectives are often used for finite object distances, in most ...
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How are co-ordinate systems built physically in curved space-time?
How do we physically choose a co-ordinate system for making astronomical observations?
In a special relativistic system, the definition of relative velocity, clock synchronization is well understood ...
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How accurate are astronomical observations around black holes? Can they distinguish between the following two scenarios?
Scenario 1
As Schwarzschild imagined. All of the matter in the black hole is at the centre, forming a singularity. The formula for the event horizon that bears his name is
$$R = \frac{2GM}{c^2}$$
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Calculating distance to galaxies seen through a telescope
When we see a galaxy through a telescope, say the James Webb telescope, it is said we see a galaxy as much as about 10 billion light years away. But 10 billion years ago we were much closer (because ...
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How is Starlight Reflected by Mirrors?
The chosen star is on the Z-axis of Mirror-A (Red). The Star image appears on the
face of this Mirror at the Origin of the CoSys.
Starlight Rays (Yellow lines) remain parallel, and do not diverge with ...
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Derive Newton's Law of Gravitation from Kepler's 3rd Law, Assuming an Elliptical Orbit? [closed]
Can you derive Newton's law of gravitation from Kepler's third law, assuming an elliptical orbit?
Most of what I've seen have been people solving it with a circular orbit. However, I find it ...
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How do astronomers measure the parallax angle?
How do astronomers measure the angle p?
"Instead of closing one eye and then the other, we observe a star six months apart, so that we are on opposite sides of the sun for each observation. ...
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$X$, $Y$, $Z$ axes for the known Universe
Does anyone know if physicists, mathematicians, or any other scientists have assigned an $X$, $Y$, $Z$ value for the known 3 dimensions we understand as 'space'?
If we were to attempt to build a 3D ...
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Detecting gravitational wave polarization
We know that in TT gauge frame the gravitational wave has two polarization components, and the actual gravitational wave we are detecting is a linear combination of those two states , now a natural ...
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How can I calculate evolutionary timescales of low mass stars?
How can I calculate how long a star of a given mass will spend on an evolutionary branch before evolving off it?
I'm thinking about the evolution of low mass stars from the subgiant branch to the red ...
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How deep can a 'deep field' image be?
Hubble's famous deep field image was created by pointing the telescope at the same spot for 10 days continously. This aggregates photons and creates a coherent image - If I understand what's going on ...
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Speed of light estimate from Io's eclipses by Ole Rømer
It can be found elsewhere that Ole Rømer estimated the speed of light (in terms of UA/h, probably) by accounting cumulative delay in Io's eclipses.
My question here is: how did he measure time with ...
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On the nature of Earth's past light cone in an expanding universe
As our telescopes look further and further from Earth, they are observing older and older cosmic phenomena. But if you look far enough to see something that occurred "shortly" after the big ...
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Synchrotron Emission: Physical Intuition for the Broad Spectrum
I understand what is happening to the electron to have it emit synchrotron light. However, I am not physically understanding the reason that a pulse of light that an observer sees will be made up of ...
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Fine structure of the hydrogen atom
How is the fine structure of Hydrogen of importance in the astronomical observations? For example: I know that 21 cm can penetrate the cloud of interstellar dust and hence allows the mapping of the ...
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What is the average prevalence/density of stars in space?
By average density $D$, I mean that, if you look at a huge volume $V$, you would expect to see $V\cdot D$ stars in that volume.
Just a rough answer is fine. I'm sure the prevalence of stars changes ...
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At what average rate do supernovas happen?
By average rate $R$, I mean I want an answer with units $$[R]=\frac{\text{supernovas}}{\text{length}^3 \cdot \text{time}}$$. That is to say, if I consider a huge volume $V$ and a long timeframe $T$, I ...
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Has MOND been tested or even confirmed for our own galaxy, the Milky Way?
MOND, based on a modifications of Newton's law for small accelerations, describes the rotation curves of stars in most galaxies, especially the outer stars.
Has MOND been tested for the stars in our ...
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Where can I find datasets for all confirmed exoplanets, terrestrial exoplanets, and Super-Earth exoplanets?
"The NASA Exoplanet Archive" (https://exoplanetarchive.ipac.caltech.edu/) implies that there are 5,197 confirmed exoplanets. The "5,197 Confirmed Planets 11/02/2022" link leads to ...
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Unusually cratered asteroid
Asteroid Mathilde is a rocky body in the solar system that seems to be more crater than asteroid.
Are these impact craters? If so, how did this body survive the impacts? It seems at first glance that ...
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Orbit of a planet around a black hole
If we observe from Earth a planet in very close orbit around a supermassive black hole (as close as possible to the black hole without the planet being swallowed up or destroyed by tidal forces), ...
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How can the distance to the sun from the earth be determined without relying on any prior baseline measurements?
I am asking if there is a way that a man could determine the distance from the earth to the sun without already having a baseline distance or dimension measurement to begin with, and without having ...
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