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Epsilon (ε) Lyrae
Optical Double-Double Star
| Right Ascension | 18h 44m 21.6s | Best Seen | 6/15 - 12/1 |
| Declination | 38° 32' 00" | Combined Magnitude | 4.67 / 4.59 |
| Apparent Separation | 211" | Constellation | Lyra |
| Epsilon Lyrae1 Northern Pair |
Epsilon Lyrae2 Southern Pair |
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|---|---|---|---|---|---|---|
Actual |
Compared to Sun |
Actual |
Compared to Sun |
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| Distance | 162 ly | -- | Distance | 160 ly | -- | |
| Separation | 116 au | -- | Separation | 121 au | -- | |
| Orbital Period | 1,800 yrs | -- | Orbital Period | ~ 725 yrs | -- | |
| Actual Brightness | -- | 19 / 6.5 | Actual Brightness | -- | 14 / 12 | |
| Magnitude | 5.06 / 6.19 | -- | Magnitude | 6.30 / 5.51 | -- | |
| Mass | -- | -- | Mass | -- | -- | |
| Surface Gravity | -- | -- | Surface Gravity | -- | -- | |
| Surface Composition (by mass) | 74% hydrogen 24% helium 2% everything else |
same | Surface Composition (by mass) | 74% hydrogen 24% helium 2% everything else |
same | |
| Spectral Type | A4 V / F1 V | G2 V | Spectral Type | A8 Vn / F0 Vn | G2 V | |
| Density (gram/cubic cm) | -- | -- | Density (gram/cubic cm) | -- | -- |
What To Look For Through The Telescope
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Recommended eyepiece: 24mm or 40 mm.
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When people look through the telescope they should see two stars near each other. One star should be slightly brighter than the other. Each star should look slightly oval shaped.
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With good atmosphere conditions and/or with good eyes, it can be seen that each star is really two stars.
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A fifth component star was discovered in 1985 that rotates around Epsilon2
Epsilon Lyrae Information:
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This is the famous “Double Double” star. (With our understanding of distances and multiple stars, a more accurate name would be the “Double Multiple.”)
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The two binocular star systems are separated by about 10,500 AU and they probably take about 500,000 years to rotate around each other.
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References
| Item | Updated | Notes |
| Coordinates | 2002-12-02 | split difference between “two” |
| Combined Magnitude | 2002-12-02 | with Scott’s The Flamsteed Collection |
| Apparent Separation | 2002-12-02 | from coordinates given in Flamsteed: |
| Distance | 2002-12-06 | with Flamsteed |
| Actual Brightness | 2002-12-06 | with Flamsteed |
| Magnitude | 2002-12-06 | with Flamsteed |
| Mass | -- | |
| Surface Gravity | -- | |
| Surface Composition | 2003-01-06 | OK for all stars |
| Spectral Type | 2002-12-06 | with Flamsteed and SIMBAD |
| Density | -- | |
| Other Information | -- |