All Questions

1
vote
1answer
98 views

What is that light of the middle of the milky way galaxy?

I'm Being confused what is that light in the middle of milky way galaxy? Image is from Charting the Milky Way From the Inside Out The text with the image explains a lot about the spiral arms and the ...
-1
votes
0answers
25 views

What is the Structure of Earth's atmosphere?

What are the Structure of the atmosphere of the earth and what is the difference compare to other planets ?
-1
votes
0answers
64 views

Are Torsors useful mathematics for modeling Spiral Galaxies? [closed]

The local interstellar cloud seems to spiral into sunspots as time approaches positive and negative infinity - behavior I've always imagined representative of spiral galaxies. I am curious if any ...
1
vote
1answer
49 views

Difference of Gas Giant Planet and Ice Giant?

What is the Difference of or the Structure of a GAS PLANET AND AN ICE GIANT Why they called ICE GIANTS like Neptune and Uranus. Do they have a similarity ?
1
vote
0answers
8 views

Clarity on dust extinction terms and implementation: R_V, A_V, and E(B-V)

I have created a model galaxy spectrum using STARBURST99 and want to compare it to an observed spectrum of a particular galaxy. I understand that I need to redden ...
2
votes
0answers
16 views

How to correct observed flux densities for redshift

Say I have a spectrum of a galaxy at a redshift $z$, in flux density units of erg/s/cm^2/Angstrom. I'd like to recover the spectrum (in the same flux density units) at z=0, i.e. at its rest ...
2
votes
0answers
85 views

How does the black hole at the center of M87 look like in the visible spectrum?

I learned here that the picture of the black hole we saw all over the news was a false color image, based on the radio spectrum emissions. How would the black hole at the center of M87 look like when ...
0
votes
0answers
32 views

The Size of the Observable Universe [duplicate]

In the history it has been demonstrated that the galaxies have gone away between if there is another thing that has allowed us to calculate the value of the acceleration of the expansion that ...
2
votes
1answer
43 views

How do radio telescopes gather information about visible light?

Is the first image of a black hole that was captured by the Event Horizon Telescope what would be seen with a large enough optical telescope (or with the naked eye from a proper distance of the black ...
5
votes
1answer
75 views

What is the force that changes a satellite’s inclination when orbiting a planet with an equatorial bulge

I tried looking this up without success and I imagine there's a formula for it, with some ridiculous numbers like it drops off to the 5th power of the distance or maybe even more. Imagine a planet ...
0
votes
1answer
72 views

Can we get the gas compositions from a gas planets? [closed]

Is it possible to get some gases like hydrogen from gas planets (Saturn, Jupiter, Uranus or Neptune)?
0
votes
0answers
26 views

On finding yesterday's star setting time if today's rising and culmination time is given

A star will rise today at 14h 56m and will culminate at 21h 49m. At what time yesterday did the star set? The refraction and horizon lowering can be disregarded.
1
vote
1answer
113 views

What is the farthest we can see into the universe?

Is there a limit in which the mass in space obscure the ability to detect anything farther even as technology progresses? Related: Can the range of the observable universe be extended through an ...
1
vote
2answers
47 views

Knowing the RA/DEC of a star how do i locate a star from ground?

Standing in Melbourne at 4 am in the morning on 14th April 2019, Sirus RA = 06h 45m 08.9s, Dec = -16° 42' 58"..How do I Locate this. Standing facing east I turn myself towards south approx 90 Deg and ...
2
votes
2answers
83 views

Can the range of the observable universe be extended through an intermediary?

I understand that the so called observable universe has a limit we cannot see through. My question is whether we might get information through an intermediate hypothetical actor located halfway to ...
4
votes
1answer
87 views

Are we looking for brown dwarfs where the dark matter has to be?

We have been repeatedly assured that their ain't enough brown dwarfs to account for all the dark matter in our galaxy. My question is have we been looking in the right places? Or in more detail. ...
0
votes
0answers
21 views

Black hole rotation and it's significance

Is there is any significance of the direction of black hole rotation with the nature of the instantaneous distortion of space-time curve, the jets coming up in the axis of black holes, and nature of ...
5
votes
1answer
304 views

Where is the intervening light in the M87 black hole?

The M87 black hole is at the centre, more or less, of an elliptical galaxy of 1 trillion or more stars. So certainly there are stars and other light emitting objects (emission nebula e.g.) in the ...
0
votes
1answer
29 views

Does interstellar cloud obstruct or reduce the visibility?

We just pictured a medium distant black hole by combining data from various observatories around the world. That's when I wondered if interstellar cloud blocks the visibility at multiple position in ...
1
vote
1answer
31 views

How does the Large Binocular Telescope resolve so well in both orthogonal directions simultaneously?

The Forbes article Ask Ethan: How Does Very-Long-Baseline Interferometry Allow Us To Image A Black Hole? includes an example of optical interferometry from the Large Binocular Telescope, shown below. ...
2
votes
1answer
49 views

What does the Sun look like from the heliopause?

I calculated the angular diameter of the Sun at the heliopause to be 0.004°. If that is correct, would the Sun appear as a disk, or like the pinpoint of light from a star? How bright would the ...
7
votes
3answers
420 views

Why does the Event Horizon Telescope (EHT) not include telescopes from Africa, Asia or Australia?

The Event Horizon Telescope seems to include these radio telescopes currently: Image by European Southern Observatory (ESO)/O. Furtak; CC-BY 4.0-licensed, see the source on Wikipedia Commons and the ...
5
votes
1answer
77 views

Superscript-subscript uncertainty notation

While reading publications in astrophysics I've encountered this kind of notation (fictitious example): $$M = 6.1^{+0.6}_{-0.1} \times 10^{30} \textrm{ kg}.$$ Several examples are here, p. 2. I ...
0
votes
1answer
85 views

Could the Sun have liquid iron in orbit?

How close of an orbit to the Sun could an iron meteor get before it melts into a ball?
0
votes
1answer
83 views

If a black hole does not emit light, how can one take a picture of the black hole itself?

There's some discussion that the image composed by the Event Horizons Telescope is really just an accretion disk. To "take an image" of something, you need the light reflecting off of the surface of ...
2
votes
1answer
101 views

Do the “schwarzschild metric” or the “isotropic metric” fit the Event Horizon telescope data on Messier 87 better?

The "Schwarzschild solution" in "Schwarzschild metric" looks like: $$\text -c^2d\tau^2=-\left(1-\frac{2GM}{rc^2}\right)c^2dt^2+\left(1-\frac{2GM}{rc^2}\right)^{-1}dr^2+r^2(d\theta^2+\sin^2\theta\,d\...
0
votes
0answers
22 views

Smoothing an SED with binning

I have an (observed) SED of a galaxy, and am attempting to match model SEDs to it. To do this I need to be able to see its shape better, which would involve some sort of smoothing of the spectrum. I ...
2
votes
1answer
50 views

Did the Moon ever approximate a geosynchronous orbit above the early Earth?

Simulations suggest the early Moon formed about 20,000 to 30,000 km away from Earth which is less than the current geosynchronous orbit of 42,164 km. The Moon is now 384,000 km away from Earth. Does ...
3
votes
0answers
57 views

What is the actual visual characteristics of a black hole?

Is there a safe distance in which a black hole can be observed with the human eye? What is a safe distance? I have seen many computer simulated and artist renditions, and I am not sure if they ...
3
votes
1answer
62 views

What is the actual resolution of Event Horizon Telescope?

I am quite impressed with the recently published image of M87* black hole. It appears that this image achieves spatial resolution well above and beyond what was available until today. But how high ...
0
votes
0answers
28 views

Where is the matter that has fallen inside a black hole?

Matter once it crosses the horizon of events is definitely forced to enter the black hole without the possibility of escaping from the intense gravitational field, so much so that even light can not ...
1
vote
2answers
40 views

What does it mean when we say that information is potentially recoverable from a black hole

My understanding is that if the surface of a black hole is holographic, then information is potentially emitted from a black hole, say due to Hawking radiation or some other means. What can say ...
1
vote
1answer
37 views

What do the lines in this Event Horizon Telescope and Global mm-VLBI Array infographic represent?

In the following EHT and GMVA diagram, what do the yellow and blue lines represent? I don't think they're physical communication lines (that would be unfeasible). Do they depict anything specific? ...
10
votes
3answers
176 views

What else could the Event Horizon Telescope Observe?

The Event Horizon Telescope was made possible in order to observe the details of supermassive black holes. This took a huge amount of work installing extra telescopes and developing the hardware and ...
1
vote
3answers
123 views

Why is the ring of light around the M87 black hole bigger than the photon sphere?

Today we know that a black hole represents a region of space where the gravitational forces are very intense, this consequence of a concentration of matter in a very small region of space. On April 10 ...
3
votes
1answer
75 views

Are there known objects rotating at close-to-light speeds?

For example, $0.1c < v < c$? Is this actually possible? Background: is that true that the black hole in the center of the Milky Way rotates once per 20 minutes?
3
votes
0answers
54 views

Why isn't the relativistic jet visible in the image of the M87 black hole?

I'm referring to the infamous relativistic jet, which consists of matter being accelerated to near the speed of light, originating at the poles of the black hole: But in the image of the black hole ...
0
votes
0answers
21 views

Why not capture also Milky Way's black hole image? [duplicate]

The world has now seen the black hole "close-up" of M87. Besides the recognition to how awesome science has become in the 21st century, I have the following question. Didn't they work also to ...
2
votes
1answer
50 views

Why the chosen orientation for the M87 black hole image?

By now we are all familiar with the official image of the black hole in M87: Now, in the universe, as far as I know, there is no up and down, nor left and right. All is relative. Hence my question: ...
1
vote
0answers
21 views

Are circumbinary and noncircumbinary habitable zones mutually exclusive?

Could a binary star system have an earth-like planet orbiting star A, a second earth-like planet orbiting star B, AND a third earth-like planet in a stable circumbinary orbit? Or does the space that ...
1
vote
1answer
67 views

M87. What was the black hole before?

10 seconds before the M87 black hole was a black hole, what was it? A star 10 times the size of our solar system?
4
votes
2answers
58 views

What resolution would earth-moon telescope achieve?

Event horizon achieved earth-size telescope by using seperate telescopes around the world to interpolate an image of a black hole at resolution of 60 arcmicroseconds. What resolution could we get if ...
5
votes
3answers
135 views

Can a star fall in a super massive black hole without getting destroyed?

This is the first of many similar questions I have to build up to a specific question or scenario that I want to explore and find an answer to.
1
vote
0answers
14 views

How do you fit a model SED to an observed galaxy spectrum with photometric data?

I have a spectrum of a galaxy from HST data and SDSS data (resulting in a nearly continuous SED from the FUV~1000 Angstroms through infrared). I have created a model SED with the galaxy simulation ...
4
votes
2answers
403 views

What is the light source in the black hole images?

What is the light source in the black hole images? I've searched the site before asking, as well as tried to google it. But perhaps the answer is buried due to the recent news. My understanding, is ...
5
votes
3answers
360 views

Why isn't the black hole white?

I recently saw the first image of a black hole. As I understood, it is covered with bright, hot matter. In this case, how can we see the black disk (event horizon), instead of a bright disk due to the ...
0
votes
1answer
80 views

Why don't we see the gas behind the black hole?

In computer simulations of what a black hole might look like and many artist renderings of black holes, they all seem to show the brightly glowing gas BEHIND the black hole due to gravitational ...
1
vote
0answers
41 views

What description of the image can we expect from the image of first black hole? [closed]

The EHT has published the first image of a black hole. I was wondering what could be the size of the original image of the first black hole and the format of the image captured?
5
votes
1answer
139 views

Event Horizon Telescope Data Cleanup

I was wondering how the researchers were able to minimize or neutralize confirmation bias regarding the data collected? As I understand it, the algorithm pruned much of the data, which would make ...
2
votes
0answers
14 views

Spectral shapes - Names used within the astrophysics community

I often hear in talks that the spectrum is "hard/hardening", "soft", "steep". Other than their literal meaning, do they scientifically mean something and what actually is the difference between them?

15 30 50 per page