Skip to main content

Questions tagged [radius]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
5 votes
3 answers
194 views

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
  • 571
3 votes
1 answer
71 views

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
124 views

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
2k views

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
129 views

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
207 views

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
131 views

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
620 views

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
78 views

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 https://exo.mast.stsci.edu/exomast_planet.html?planet=55Cnce
Physics Geek's user avatar
0 votes
1 answer
237 views

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
692 views

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
1k views

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
  • 17.5k