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25 views

How do I calculate B-V to make a Hertzsprung Russell diagram?

I am reading my textbooks and a few "Astro101" websites, but I cannot find a final answer to this: In the $B-V$ colour index that is plotted in an H-R diagram, are $B$ and $V$ the (observed) apparent ...
1
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1answer
42 views

Could someone please explain to me how I can extract velocity component values from Stellarium, for a given planet?

For a project that I am currently working on, I would like to know how one could extract velocity component values ($v_x$, $v_y$ and $v_z$) for a planet from the Stellarium software. The current ...
5
votes
1answer
105 views

Why is a giant planet around a tiny star unusual when binary stars are normal?

Inspired by this BBC article and the corresponding journal article about the M dwarf star GJ 3512. The Jupiter-like world is unusually large compared with its host star, contradicting a widely held ...
3
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0answers
74 views

Can someone calculate the age of the KOI-4878 star?

The star’s low metallicity and fairly high space velocity suggest that KOI-4878 is older than the Sun. But I don't know how to calculate an estimation for the age. KOI-4878 data on Simbad
2
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1answer
96 views

Universe expansion

I'm reading the book "The theory of everything". In the second chapter it says the Universe is expanding, and we know this because the measurements made using the doppler efect to other galaxies gives ...
2
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1answer
60 views

What might some examples be of radio telescope interferometric arrays made from “cheap components relying on massive computing power”?

This answer mentions that there are some interferometric radio telescope arrays ...consisting of very cheap components relying on massive computing power to retrieve the signals from noise... The ...
0
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1answer
70 views

Questions about amateur astrophotographer Nik Szymanek's telescope

The 2011 Sixty Symbols video Spy Satellites (from Deep Sky Videos) shows amateur astrophotographer Nik Szymanek and his telescope. Question: Can someone identify the model and design of this ...
4
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1answer
69 views

What is the LSST's plan to address frequent satellite trails in data?

In the 2011 Sixty Symbols video Spy Satellites (from Deep Sky Videos) after about 01:40 amateur astrophotographer Nik Szymanek says: One thing I find when I’m ...
6
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1answer
757 views

What cluster of stars is this with a “dark donut” to one side?

In the 2011 Sixty Symbols video Spy Satellites (from Deep Sky Videos) after about 01:44 amateur astrophotographer Nik Szymanek shows an image of a cluster of stars ...
1
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1answer
124 views

What would we notice if the Sun stopped fusing atoms? [duplicate]

(This question was stimulated by Would we have more than 8 minutes of light, if the sun "went out"?) According to this answer, the "Sun has enough gravitational potential energy to supply ...
5
votes
2answers
100 views

How would a small nearby black hole be detected and confirmed as such?

This article suggests that there might be a tennis ball-sized black hole orbiting the Sun somewhere beyond the orbit of Neptune. According to the article, observational anomalies of trans-Neptunian ...
0
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0answers
37 views

What is the largest cluster of merging galaxies?

Reading about the Andromeda–Milky Way collision, a galactic collision predicted to occur in about 4.5 billion years between the two galaxies, I went to the galaxy merger page and Wikipedia states that ...
2
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0answers
50 views

Feasibility of radioastronomy in densely populated areas

In general, radioastronomy as well as optical astronomy depend on a good SNR. This meant to position telescopes as far as possible from noise sources. Optical telescopes were built at elevated points ...
3
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1answer
48 views

Exoplanets, Protoplanets, and planetesimals

So, most of the mass of the solar system (that isn't inside the sun) is inside Jupiter. And most of whats left after THAT is inside Saturn. So, all the rocky planets, moons, and asteroids in our solar ...
-1
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1answer
91 views

Black holes exhaustion

Can accelerating black holes radiate their mass as an gravitational wave?If that is true maybe dark matter is not something but it is just gravitational waves from an exhausted dense object.
52
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2answers
12k views

Would we have more than 8 minutes of light, if the sun “went out”?

The common theory is, that if the Sun "shut down", we would see the light for eight more minutes (the time that it takes the photons to reach the Earth). However recently I have read that photons ...
4
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2answers
121 views

Can we calculate the orbit of exoplanets?

I'm not an astronomer, but the question came up and I'm interested if we are able (or how accurate we are able) to calculate the orbital parameters of an exoplanet. Since the transit method must yield ...
-2
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1answer
49 views

how are the celestial objects measured? [closed]

So I am guessing that chemical composition of the starts is measured using the spectrum analysis of waves emitted by them. But what if the spectrum is super packed by different wave lengths? How do ...
23
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1answer
1k views

How fast are we moving relative to the CMB?

The cosmic microwave background radiation should provide kind of a global reference frame, because you can determine your speed relative to it using the redshift. Is it known how fast we are moving ...
2
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1answer
77 views

A question related to black holes

Not a physicist just a simple guy, don't know much about physics as well. Just like to read things. I was reading about black holes and a question popped in my mind. If I understand it correctly ...
3
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2answers
39 views

Night-Day Cycles in S-Type Planetary Systems

I am a writer and space enthusiast. For a story I am currently writing I would like to have a planet which orbits a star which resembles the sun, which in turn orbits another star. In this situation ...
3
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2answers
64 views

What kind of star would allow for life like our Sun/Earth and then go nova?

In the Star Trek Prime Universe, Star Trek: The Original Series, the home stars of the Fabrini, Platoans and Sarpeidons went nova, while in Star Trek: The Next Generation one of the stars in the ...
7
votes
1answer
53 views

What is the gravitational lensing focal distance of a white dwarf star?

I tried looking this up, but I couldn't find any formula on gravitational lensing distance. I know that our Sun's is about 550 AU, though further distances work too, as it's not a single focus due ...
5
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2answers
97 views

Can a planet exist with the same mass as the earth, but have a different diameter?

Can there be a planet with the same mass, and a similar composition, as the earth, but with a larger or smaller diameter, and how could that theoretically occur? I've tried to see if there is any ...
18
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2answers
3k views

How do we know Nemesis is not a black hole (or neutron star)?

Nemesis, the hypothetical "death star", is supposed to be a massive body that orbits the Sun at long distances and periodically sends comets from the Oort Cloud into the inner solar system. These ...
0
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1answer
98 views

Cosmological redshift - How do we know it's not caused by the observer's time dilation?

Instead of cosmological redshift being caused by the metric expansion of space, why couldn't cosmological redshift be caused by our perspective moving faster in time? Said another way, if the ...
3
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0answers
51 views

What is the apparent magnitude of the faintest stars visible during a full moon?

Assuming the viewer is far from any light pollution, it is a cloudless night, and humidity is very low. What is the faintest apparent magnitude of stars visible to the naked eye during a full moon (...
1
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0answers
25 views

Are there any openly available simulators describing how planets form from protoplanetary disk?

Out of pure interest, I wonder whether there are existing open-source simulators that can simulate the formation of stars and planets from a protostar and the surrounding protoplanetary disk?
1
vote
2answers
71 views

Does the Lagrange L1 point have a 'size'?

Like in cubic kilometers, what is the size of L1 "area of influence"? being unstable I guess that size can vary?
1
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2answers
124 views

Minimum Telescope Needed to See Saturn's Rings

I am a total novice. My daughter, likes Saturn. Since Saturn is so close I thought it was a good time to view it with her. What are the minimum needed telescope specs? GC Update: Can answer ...
3
votes
1answer
239 views

Is there any site with telescopes data?

Is the data gathered from telescopes "open source"? If so, is there any website that group it all?
0
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0answers
36 views

Use of an Equatorial Mount [duplicate]

What is Equatorial Mount in simple terms? What is polar alignment? What will happen if we use an Equatorial Mount without polar alignment? And if we polar align how can we point at other stars?
2
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1answer
38 views

Where can I find the previous years' International Astronomy Olympiad question papers?

I have looked at the official site but the link for previous papers isn't working.
1
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1answer
78 views

How much infrared radiation is emitted by a bow shock?

Has the amount of energy being emitted from R Hydrae's bow shock been studied? If so, is there any information how much infrared radiation is emitted in any means of measurement? If the infrared ...
4
votes
0answers
50 views

Counter clockwise rotation of storms at Jupiter's north pole. What explanations have been proposed?

On Earth, high pressures and low pressures occur interchangeably. So that where two pressure systems intersect, they move the air in the same direction. But as Juno revealed the first observations of ...
0
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0answers
38 views

IAO 2015 Question 1 Noon at the Olympiad

Yesterday, on October 16, 2015, the upper culmination of the Sun at the venue of the Olympiad was at 11:29:44 local time. Calculate as accurate as possible at what time the upper culmination of the ...
18
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4answers
8k views

Would an object shot from earth fall into the sun?

Would an object shot from earth fall into the sun? If an object is shot at 107,000 km/h via rocket or otherwise, in the opposite direction to our orbit about the sun, it will be traveling at 0 km/h ...
8
votes
2answers
243 views

Why is ice on Mars not covered in dust?

There's exposed water ice on Mars, like in craters like this At the same time, Mars has dust storm, covering the solar panels of rovers, and occasionally covering the entire planet So why is this ...
6
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0answers
1k views

If a spaceship ran out of fuel somewhere in space between Earth and Mars, does it slowly drift off to the Sun? [migrated]

Pretty much what the title is saying. I feel like I am missing something fundamental here and this is driving me crazy. Does a spaceship which is out of Earth's gravity drift to the Sun eventually?
1
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0answers
36 views

Derivation of a formula for the mass of a tidal bulge and tidal torque

I've been looking into the tidal mechanism for a binary star system and seem to have hit a brick wall. In the literature (see below), little explanation is given to justify the equations (9.60), (9.61)...
4
votes
1answer
54 views

How does the number in stellar classification indicate properties within the range of that class?

I am doing some research for a video game and I wanted to store stellar data on a star, such as its Stellar Classification, and then from that derive a physical appearance in the game. These are ...
5
votes
1answer
340 views

Is the resulting light from a supernova a product of photons bouncing around in the Sun?

I was thinking about how photons formed in the centre of the Sun take quite a long time to exit the surface. And it occurred to me that at the end of a star's life (during a supernova, given that it's ...
2
votes
3answers
141 views

How does time work beyond the cosmic event horizon?

The faster you move through space, the slower you move through time - the calculations show that as you approach lightspeed, time comes to a standstill. How does time work beyond the cosmic event ...
3
votes
1answer
40 views

mm-wavelengths Moon map, scientific case

I would like to test a telescope with a Moon observation. It is a low spectrometer-imager at 110-300 GHz with a resolution of 4 arcmin@150 GHz. Is there any scientific target that concerns the Moon ...
4
votes
1answer
107 views

Visitors that became satellites?

To anyone's knowledge, has there ever been an object that approached the earth and was captured into an orbit? Is it thought that there might be such objects simply too small to spot or just not ...
3
votes
1answer
93 views

Propagate Earth trajectory for 1 Myr

What is the most accurate way of propagation of Earth trajectory relatively to the Sun? I need to calculate the Earth-Sun distance. Is there any library on Python? I've used before JPL Horizons, ...
0
votes
1answer
69 views

Moon changes position

So most nights the Moon usually rises on the right of the sky when I look through the window just like the previous night. But this night the Moon was on the left of the sky rising. Does anyone know ...
1
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0answers
50 views

Does the spin rate of a black hole correspond to a physical feature?

If the mass and orbital period for two neutron stars is known before collapse to a black hole and the rate of spin is known after collapse, 100 revolutions per second for instance, that will correlate ...
1
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0answers
60 views

The energy density of DM (to be fluid,state parameter=-2)increases with time. Does it violate the concept of accelerating universe?

We know that dark energy with value of state parameter $\omega<-1$ is called phantom dark energy model. In this model if we assume dark energy to be a fluid with value of state parameter $\omega=-2$...
2
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1answer
52 views

How many Moon's Topocentric Conjunction occurs per lunar month?

It is clear that only one Moon's Geocentric Conjunction occurs per lunar month, what about the Topocentric Conjunction for a given location? without scale I can imagine many Topocentric Conjunctions ...

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