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Black Holes or Black Hole Stars? Astronomers Spar over 'Little Red Dots'

105 points · 61 comments · jandrewrogers

jahnu · 1789828933 · focus · HN ↗
One thing worth noting is our popular notion of what a star seems to be is quite different from what astronomers have.
One example, Canis Majoris has a radius of about 1420 solar radii. But its mass is roughly 17±8 times the mass of the Sun and therefore an average density of 5.33 to 8.38 mg/m3. “It is over 100.000 times less dense than Earth’s atmosphere at sea level.”
<a href="https://en.wikipedia.org/wiki/VY_Canis_Majoris" rel="nofollow">https://en.wikipedia.org/wiki/VY_Canis_Majoris
<a href="https://nineplanets.org/vy-canis-majoris/" rel="nofollow">https://nineplanets.org/vy-canis-majoris/
1. dylan604 · 1789851841 · focus · HN ↗
  I love astronomy simply for things like "17±8 times the mass". That's ~50% acceptable variance. I wish I could apply that logic to my creditors.
  1. kulahan · 1789855321 · focus · HN ↗
    I worked for a financial org with over a trillion in assets, and they had a 100% acceptable variance on project length predictions. Made for a laid-back atmosphere at work but boy. How they ever swung that is beyond me.
    “We predict a year, so it’ll take anywhere between 8 seconds and 24 months!” AND IT WORKED???
  2. e_l · 1789891833 · focus · HN ↗
    Yeah, Physics (and particularly astronomy/cosmology) often have huge variances, some of which are even greater.
    An example being the number of stars in the (observable) universe which ranges from 10^22 to 10^24 stars...a variance of 100x (or ~10,000%)!!! <a href="https://www.esa.int/Science_Exploration/Space_Science/How_many_stars_are_there_in_the_Universe" rel="nofollow">https://www.esa.int/Science_Exploration/Space_Science/How_ma...

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