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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1answer
588 views

Angular Diameter Distance

The definition of the angular diameter distance is the ratio of an object's physical transverse size to its angular size. However when I was reading my textbook, Astrophysics in a Nutshell by Dan Maoz ...
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46 views

What's the profound reason(s) why the star formation rate drives the scatter of the mass-metallicity relation in galaxies?

Since decades it's well known that a correlation between stellar mass and metallicity (Z; both stellar and gas-phase Z, but here I focus on the gas-phase Z) exists (e.g., Tremonti+04; analysis of >...
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1answer
91 views

Are large body orbits self correcting?

If a rogue planet disrupts Earth's orbit slightly to cause a long winter or summer will the Earth's orbit normalize back close its original orbit over time? Could a Planet X or some other elliptical ...
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1answer
116 views

What types of star do we know are hostile to life (like ours)?

Certainly all stars have enough energy for a planet to host life. But a more magnetically active star is not preferred because solar ejection could strip planets of their atmosphere. What's the right ...
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1answer
404 views

Why smaller black holes are considered to be more dangerous than bigger black holes?

More massive the body is more is the gravity.Still often smaller black holes are considered to be very dangerous than the bigger ones,why?
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1answer
74 views

Question on Friedman equation involving cosmological constant

This is the question: By considering both the Friedmann and acceleration equations, and assuming a pressureless Universe, demonstrate that in order to have a static Universe we must have a closed ...
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3answers
329 views

Why do neutron stars collide instead of just revolving around each other like planets revolve around the Sun?

We know about events like two neutron star colliding and resulting in a black hole, also collision of black holes, and collision of galaxies. But we never see a satellite such as a moon colliding with ...
3
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3answers
108 views

Account for radiation energy in the statement “total energy of universe is zero”

I've read in Hawking's book The Theory of Everything that total energy of the Universe is zero. He explained this by saying that if there are two bodies separated by a distance and having some mass, ...
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1answer
52 views

When black holes forms out of a supernova do they have a very high velocity?

When black holes forms out of a supernova do they have a very high velocity ?? Or do they remains at the position of parent star ??
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1answer
86 views

GW from merging of neutron stars and black holes

If it had been detected gravitational waves from merging of black holes (BH), and neutron stars (NS), why there are no detection of black holes merging with neutron stars? Why a BH-NS merging should ...
4
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1answer
113 views

Calculating obital velocity from radial velocity

I'm not really a physicist so I don't know if it's possible to get the real orbital velocity of a star from its radial velocity. I'm working on a paper for school and I want to get the mean velocity ...
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1answer
44 views

Photometric redshift

I have decided to do undergraduate thesis on "estimating photometric redshift" or something related to this using machine learning. Reading previous papers, I have come to know that work has been done ...
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1answer
187 views

How to compute the perihelion precession of Earth's orbit?

I want to simulate the perihelion precession of Earth. I tried searching other posts in stack exchange as well relating this question but may be it's my fault that I couldn't understand their answers....
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1answer
154 views

What is equation of straight line for a ideal blackbody on the color color diagram?

The color-color diagram is a plot between $U-B$ vs $B-V$ values. For a ideal blackbody, what is the equation of this line? In other words, what does the linear relation between $U-B$ and $B-V$ look ...
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1answer
136 views

Flatness of celestial systems like galaxies and Solar System [duplicate]

If we look around the cosmos, we will see most of the systems are just flat disks. Either it is solar system, galaxies, or the rings of Saturn. What is the matter, does it depend on how they were ...
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44 views

Study astrophysics [closed]

I don't know where to ask this question and I have found this site. If this is not the right place to ask it, please tell me and I will delete it. I'm a computer engineer for 20 years but my true ...
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3answers
7k views

What would happen to a polished marble statue left in space for a million years?

Consider it doesn't collide with any other objects. Would it be preserved perfectly in the vacuum or would its surface be damaged by anything like UV rays, radiation, gas, space dust, etc?
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2answers
328 views

The CNO cycle in first generation of stars

I'm an undergrad interested in astophysics and this question struck my mind: As the CNO cycle requires carbon to start, and carbon is produced by thermonuclear fusion in stars, is it fair to think ...
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1answer
124 views

Why does kerr black holes have a ring shaped singularity rather than point?

I read about ring singularity on Wikipedia and didn't quite understand the flow of liquids inside a rotating body causing a ring shaped singularity with zero thickness. Moreover is it specifically ...
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1answer
387 views

Can a star eat a black hole?

I know there are stars much larger than the sun and that we've discovered "small" black holes, so, let's say that the Pistol Star, which is at least 80x the mass of the sun, and the smallest known ...
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454 views

Is it “weird” that all disc galaxies rotate once every billion years?

In a recent paper (Cosmic clocks: A Tight Radius - Velocity Relationship for HI-Selected Galaxies by Meurer, et al.), it was noted in the conclusion that: [This] implies a constant orbital time of ∼...
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1answer
157 views

Gravastar Star With no Horizon with ultracompact and very density possible?

Is that possible with some strange Quantum Effect could give rise to a completely new kind of a star? Gravastar(Gravitational Vacuum Star) an object hypothesized in astrophysics as an alternative to ...
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2answers
251 views

Can BY Draconis variable stars sustain any form of complex life?

I wanted to ask this, because while I was working on two fictional planets back on the Worldbuilding SE, one of them being habitable, which orbit the 61 Cygni A star of the 61 Cygni binary star system,...
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0answers
398 views

Gravity on a right rectangular prism? [closed]

Let's assume there is a right rectangular prism floating about in space, what would the gravity be like across its 6 flat surfaces? What gravity would you experience if you set foot on the rectangular ...
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1answer
64 views

What does the word “compact” mean in astronomy/astrophysics?

I have seen countless times the adjective "compact" in astronomy, e.g. compact stars, compact binaries, etc. I would like to know, what exactly is this supposed to mean? From this source, I am led to ...
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1answer
62 views

Spectrum of star

I constructed a telescope and fixed my mobile's camera to the eye lens. I then viewed the sky via the mobile and I captured this image. This is the magnified version of it: I'm not sure if this ...
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1answer
212 views

What do the acronyms in “AT 2017 gfo” mean?

About 11 hours after the detection of GW170817 by Ligo/Virgo and the quickly succeeding detected GRB170817, a transient afterglow in the optical-nIR frequency appeared which showed many signs of r-...
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1answer
333 views

How does space time differ between galaxies? [duplicate]

Does the gravity wells differ enough between galaxies to have different speeds in space time? How much slower in space time would the biggest galaxy have compared to the Milky Way?
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2answers
86 views

What happens if one day aliens want to talk to us. How can we talk to them? [closed]

Always I wonder about that if some day alien wants to talk to us, then how can we talk to them? They didn't know any of the language on the Earth. What will be the basic building blocks for it?
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1answer
112 views

Thought experiment about our location in the Universe [closed]

[I am sorry if this isn't the best place for this - it was either here or maybe on the Worldbuilding SE.] I recently re-read one of my favourite childhood sci-fi books (Chocky by John Wyndham), and ...
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1answer
121 views

Unidentified color changing object in sky [duplicate]

Yesterday, I was just star gazing and I noticed some star-like object moving with a high speed somewhere near the Orion's Belt and exhibiting all the seven colors i.e VIBGYOR and after a few moments, ...
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1answer
179 views

If the Universe is Flat, why does it look 3D from our View?

So I know that the universe is flat in a 4D point of view, but what about a 3D point of view? The universe does not SEEM flat from our view, so how can it really be so? Please answer more simple, im ...
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0answers
52 views

Modern Astrophysics [closed]

I was wondering whether it has proven whether the universe is expanding and if so, what is its ratio, one more question that whether it has an effect for the centrifugal forces, i.e gravity and the ...
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0answers
73 views

What is known about the angular momentum distribution within galaxy clusters?

I recently saw a 3D-plot of proper motions of galaxies within the Laniakea super-cluster (https://sketchfab.com/models/754cb85550fb42588175f8a215718521). Is a similar 3D map of the vector field of ...
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1answer
952 views

What is a stellar laser or stellaser? [closed]

I was watching the latest episode of Isaac Arthur and he was talking about a stellar laser or stellaser which was coined by a scientist named Steve Nixon. I can find no information about stellasers on ...
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2answers
616 views

If the Earth is rotating counter clockwise, how does the sun rise from east?

I was very confused when I watched this video from 2:18 till 2:45. And it seems very clear that if the Earth is really rotating from west to east, shouldn't be the Sun rising from west and setting in ...
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1answer
69 views

Is diffuse energy distribution considered in the galaxy rotation curve explanations?

Problem number 23 in chapter 1 of Purcell's "Electricity and Magnetism" Second edition page 37 shows that 90% of the energy stored in the electrostatic field of a spherical charge distribution of ...
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1answer
87 views

How do comets and other solar system bodies gain energy to exit the solar system?

I recently learnt that some comets like C/1980 E1 (Bowell) interacted with objects like gas giants in the solar system and gained enough energy to exit the solar system. But from Physics, I know that ...
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1answer
61 views

false to stable vacuum transition [closed]

if the universe transitioned from a meta-stable vacuum to a stable vacuum we assume a universal death scenario. However since it cannot propagate faster than the speed of light, from any particular ...
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2answers
2k views

Why doesn't the Earth's rotation throw us off the surface?

The Earth is spinning at about a thousand miles per hour. Shouldn't we be thrown from its surface? Yes I know someone would comment "gravity" but physically we should be thrown from Earths surface. ...
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1answer
143 views

Delay between neutrino pulse and visible flash of supernova

If you were orbiting a star undergoing a core-collapse supernova, what would be the delay between the neutrino pulse from the collapse and the first visible effects on the surface? Basically, I'm ...
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1answer
94 views

What happens to the momentum of a star as its mass is converted to energy? [closed]

Stars move relative to many frames of reference. We can use the CBR for this question, I suppose, but it may not matter. Their momentum p=mass x velocity. Stars lose mass as it is converted to ...
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2answers
397 views

Assume that a star has a uniform mass density. Then how does the temperature scale as a function of the distance to the center?

Assume that a star has a uniform mass density. Then how does the temperature scale as a function of the distance to the center? Note: I am not looking for an answer that involves derivations or ...
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1answer
1k views

How do you convert an observed magnitude to a flux? [duplicate]

For a series of supernovae I have the observed magnitude and I want to convert these values to flux. I understand that I need to apply: m - M_r = -2.5log_10(F/F_r) where M_r is a 'reference ...
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4answers
1k views

If I want to learn about astrophysics, should I study up on mathematics?

I am currently reading A Brief History of Time and while the book itself does not contain much mathematics in it, I want to learn more about the concepts Prof. Hawkings talks about more in-depth. Now ...
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1answer
294 views

Astrodynamic Canonical Units [closed]

Maybe this is more appropriate for the Physics or Maths, but anyway. I am struggling with applying Canonical units with formulas. I am struggling specifically with how they are used, am I to convert ...
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1answer
143 views

The consequences and the mechanisms of a shift of the Earth away from the sun

First premise: I have already made this question in the worldbuilding section, but since it is a very specific question many have recommended me to write in the astronomy section so here we are. ...
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1answer
209 views

What should I read next after Neil deGrasse Tysons “Astrophysics for people in a hurry”? [closed]

I really liked the clever way the author explained stuff in this book but I already understood most of it. Neil himself states in the book that if you are not in a hurry and want to know more about ...
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2answers
148 views

Why do stars born in cluster finally drive away from each other

In other words, if a group of stars born within the same nebula, e.g. Pleiads, are initially gravitationally bound - what causes them to finally get separated and proceed individually? Is it the ...
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2answers
572 views

What happens if a white dwarf collides with a star like our sun or a red dwarf?

Would it explode in a supernova or will it form a new star?