Questions tagged [radius]
The radius tag has no summary.
14 questions
4 votes
0 answers
114 views
What is meant by the 'King core radius'?
While looking for a parameter that represents the extent of a star cluster, I came across the King core radius ($r_c$). However, even after reading papers, I still don’t understand it. What does the ...
- 51
3 votes
1 answer
685 views
How do I find the luminosity of a star as it evolves through its entire lifetime
I am really confused on how to estimate the luminosity of a made-up star through its lifetime, like say a star with the mass of 0.902 suns, how would I find the luminosity of it say, 6.5 billion years ...
- 39
3 votes
1 answer
449 views
What's the radius of Mars over Mount Olympus?
According to Mars mass compared to earth, the Equatorial radius of Mars is 3396.2 kms and the Polar radius is 3376.2 . But I want to know the radius of Mars over Mount Olympus and it wont be the same ...
- 1,375
5 votes
3 answers
422 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 ...
- 719
3 votes
1 answer
99 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) ...
2 votes
1 answer
157 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: ...
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)...
- 1,913
3 votes
2 answers
234 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 ...
- 131
3 votes
1 answer
239 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?
- 1,738
2 votes
2 answers
191 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?
- 555
4 votes
4 answers
890 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 ...
- 6,892
1 vote
2 answers
115 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
- 51
0 votes
1 answer
919 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 ...
0 votes
2 answers
2k 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 ...
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