Star Systems » The Epsilon Eridani Star System

To return to our main subject. Epsilon Eridani is a young star – its age is often stated as being about 800 million years. This means that any earth-like planet is likely to exist under similar conditions to the age of the late bombardment or perhaps the very beginning of life. It is if particular interest as we may be looking at a star system similar to our own Solar System in the early years of its formation. Epsilon Eridani is somewhat less massive than the Sun and far less luminous (about 30 per cent solar). It is a fourth magnitude star, a mere 10.5 light years away, and is the 10th closest other star system to the Sun. Its rotation speed appears similar to that of the Sun and it displays considerable solar-like activity. Unlike many stars so far found to have planets, Epsilon Eridani is not 'metal-rich', its 'metal content' is actually a bit less than that of the Sun (metallicity about 80 percent solar). It belongs to the spectral system K2 (the Sun is G8). As such its surface temperature is lower than the Sun at about 5080 degrees Kelvin (88 percent). Of very great interest are the results of recent observations.

On 27 October 2008, at the 5th Spitzer Conference devoted to results from the infrared Spitzer Space Telescope, a team of astronomers using NASA's two infrared cameras and an infrared spectrometer on the telescope announced evidence that the Epilson Eridani system has two asteroid belts made of rocky and metallic debris left over from the early stages of planetary formation. The innermost debris belt is located roughly around the same position as the asteroids in our Solar System and is rich in silicate dust whilst the second, denser belt (which is also mostly likely to be composed of bodies rich in rock as well as ices) lies between the first belt and a broad, outer ring of icy bodies at 35 to 90 AUs out from Epsilon Eridani. This is similar to the Solar System's Kuiper belt. Its relatively low luminosity means that its habitable zone is far closer to the strar and lies somewhere between the distances of Venus and Mercury from the Sun. Being less massive than the Sun, it has a longer life time – about 15 billion years compared to the Sun's 10.5 billion so there would be plenty of time foe life to develop and flourish on a suitable planet if one such world existed. In fact it seems quite a high possibility that there is an inner E.Eridani system similar to our own Mercury, Venus, Earth/Moon and Mars. The star is known to have at least one gas giant planet but at least two more gas giants are very probable as shown in the diagram on the right above. (Credit for diagram NASA/JPL-Caltech). With reference to the habitable zone a comparison with our own Solar system is shown below. (Credit for the diagram is given to the website published in both English and German.)

Ray Goodwin

Somewhere there are mountains
Glistening in the snow
Somewhere there are mountains
That we shall never know

Somewhere there are rivers
Flowing fast and free
Somewhere there are rivers
That we can never see

Somewhere there are oceans
And sun drenched island sands
Forests full of creatures
In vastly distant lands

Somewhere there’s a planet
Beneath an alien star
The people watch our tiny sun
And wonder where we are

One day perhaps we’ll find them
Across the void of space
Perhaps through ways as yet unknown
We’ll meet them face to face

The author of this web site Ray Goodwin holds B.Sc. Degrees from London University in Chemistry, Geology and Physiology and an M.Sc. in Biochemistry. He has spent most of his professional life teaching in Colleges of Technology. On his retirement he has entered the fields of astronomy, astrochemistry, astrobiology and space sciences. He has spent a great deal of his retirement in visiting amateur astronomy societies and in attending European Space Agency Symposia in ESTEC in the Netherlands and other scientific conferences in England and Sweden. He regularly attends the yearly European Astrofest in South Kensington London and other meetings in the UK. He has written scientific articles and given a number of lectures on diverse scientific subjects.

Readers of this web site are invited to e-mail the author ( and discuss their opinions of the topics dealt with and suggest any changes which they think may be helpful.

Life in the Cosmos Website
Version 01.00 - April 20, 2015.