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Size: 2433
Comment:
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Size: 722
Comment:
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| Deletions are marked like this. | Additions are marked like this. |
| Line 8: | Line 8: |
| . about 20 M⊙ | . about 20 M⊙ , 51 kpc away. |
| Line 14: | Line 14: |
| || 3 million years ago || end of Pliocene || began burning helium (in core) || || 20 thousand years ago || Lascaux || began burning carbon (in core) || || 1980 || || began burning neon and oxygen (in core) || || 1987 Feb 20 || || began burning silicon, producing an iron core || || 1987 Feb 23 7:35 UT || || explosion || ------ ==== related information ==== Type II supernovae (SnII) are the explosion of stars between 8 and 40 M⊙ (solar masses) at the end of an 10 million year lifetime for a 25 M⊙ star. Estimated 0.02 SnII per year in our galaxy - most not visible. If the galaxy has 200 billion stars, the rate is 1 in 1e13 SnII per year. If there are an average of 200 stars within 20 light years (6.14 parsecs), then within radius R (in parsecs) there are 0.864 R³ stars, or 8.64e-14 R³ SnII per year. The average time between SnII versus distance, rounded to an order of magnitude, is : || 1 pc || 10 Ty || || 2 pc || 1 Ty || || 5 pc || 100 Gy || || 10 pc || 10 Gy || || 20 pc || 1 Gy || || 50 pc || 100 My || || 100 pc || 10 My || So, over the next 5 billion years, our solar system might see 5 SnII within 20 parsecs distance, and 50 SnII within 50 pc. The brightest star in the sky, Sirius, is close but only 2 M⊙. Canopus is 9 M⊙ and a possible SnII candidate, but 100 pc away. In 10 My, with a radial velocity of 20 km/s (assumed positive), it will be more than 200 pc further away. |
|| 3 million years ago |
End In Fire
The supernova in the Large Magellanic Cloud
Paul Murdin, Cambridge University Press, 1990
About SN1987A, a.k.a. Sk-69 202 in the Large Magellanic Cloud, which University of Toronto astronomer Ian Shelton first observed 1987 February 27 with the 24 inch telescope at the Las Campanas Observatory in Chile.
- about 20 M⊙ , 51 kpc away.
page 71: Timeline for SN1987A (need observed aftermath)
Observed time |
epoch |
status of star |
20 million years ago |
Miocene |
star formed, burned hydrogen for some 15 million years |
|| 3 million years ago