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Questions tagged [radius]

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5 votes
3 answers

Why are there gaps in the size distribution of solar system moons?

Looking at the moons natural satellites in the solar system, the larger ones appear to fall in a few groups of sizes. Eyeballing the above picture, there appear to be a bunch of big moons (the ...
JanKanis's user avatar
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3 votes
1 answer

Most accurate way of measuing the radius of a rubble-pile comet in an N-body simulation?

I have written an N-body simulation (close to finished) in C++ which focuses on the tidal disruption of comets. I allow comets to be constructed in 2 ways: Via my HCP (hexagonal-closest-packing) ...
Gregor Hartl Watters's user avatar
2 votes
1 answer

How to use SExtractor to calculate Petrosian Radius?

I'm using Sextractor to run some benchmarks on the code I'm working on. I'm mainly focused on Petrosial Radius (PETRO_RADIUS). I have two main questions that I could not find in the documentation: ...
Igor Kolesnikov's user avatar
14 votes
1 answer

What is going on with this (sub?) brown dwarf WISEPA J174124.26+255319.5?

In this Wikipedia article, it details about a T9 class brown dwarf named WISEPA J174124.26+255319.5. Apparently, this brown dwarf has 0.95 Jupiter masses, and 0.4 Jupiter radii (with rather low error)...
Max0815's user avatar
  • 1,862
3 votes
2 answers

Small Angle Approximation Discrepancy in Horizon Dip Angle

Let's get back to the classic astronomical problem of calculating horizontal dip angle using small angle approximations. Let, our observer is a point object situated at an height $h$ on the earth ...
Rangan Aryan's user avatar
3 votes
1 answer

What is the maximum radius of an Einstein ring?

Is there an upper limit to how far out an Einstein ring can be visible? For black holes, is it a fixed multiple of their Schwarzschild radius?
2080's user avatar
  • 1,888
2 votes
2 answers

Finding stellar radii

Is apparent magnitude of star, distance(in pc) and effective temperature enough to calculate its stellar radii or we need some extra information?
Particle king's user avatar
4 votes
4 answers

Gravity inside a star?

Recently, I answered this question and need some clarification regarding the gravity when within the radius of a star. I thought that, when something is inside a star (ignoring drag), it will ...
WarpPrime's user avatar
  • 6,673
1 vote
2 answers

How Can I interpret this particular light curve without reading data on the side

There is only one dip in flux recorded. How can I interpret this particular light curve and find planetary radius
Physics Geek's user avatar
0 votes
1 answer

How can I find the radius of a exoplanet using doppler spectroscopy [closed]

I have the stellar and planet mass, planet velocity, radial velocity of star, stellar semimajor axis. How should I go about to find the radius of this exoplanet?
Oop's user avatar
  • 83
0 votes
1 answer

Simple definition of Bondi Radius

Can anyone help me by defining what is exactly Bondi Radius? I have searched far and wide but the results are very complicated and so far I have only rough idea of it but I just cant explain it very ...
Agustine Budiayawan's user avatar
0 votes
2 answers

How can the radius of a star be measured using parallax?

The radius of Betelgeuse was measured using parallax. From the Wikipedia article: the estimated parallax from the Hipparcos mission was 7.63±1.64 mas, yielding an estimated radius for Betelgeuse of ...
usernumber's user avatar
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