In the night sky: Orion
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4.3.3 Gliese 581

Figure 26 An artist’s conception of the inner planets of the Gliese 581 system and their host star, a red dwarf star.
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Three planets have been found orbiting the red dwarf star Gliese 581, which is about 20 light years from the Sun.

They are named Gliese 581 b, c and e. The smallest, Gliese 581 e, has a mass just under twice that of the Earth, but orbits more closely to the star.

You may find references to Gliese 581 d, f and g. These were planet candidates, but it was later confirmed that the variations in stellar activity were giving rise to ‘astrophysical mimics’ in the radial velocity measurements, leading to spurious results.

Activity 4.3

Spend 10 minutes doing some research into the planets Gliese 581 b or Gliese 581 c.

  • How big is it?
  • Is it more like Earth or Jupiter?
  • How far from the central star does it orbit?
  • Do you think any of the planets around Gliese 581 could be habitable?

Write a paragraph about your findings.

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◄Contents►Next: 4.3.4 Transit experiment

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