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Mu (μ) Cephei
Red Supergiant Star
| Right Ascension | 21h 43m 30s | Best Seen | 6/1 - 2/15 |
| Declination | 58° 46' 48" | Magnitude | ~ 4.0 |
| Constellation | Cepheus | ||
| Actual | Compared to Sun | |
| Distance | ~5300 ly | -- |
| Actual Brightness | -- | -- |
| Surface Temperature | ~5,400 °F | ~0.56 |
| Diameter | ~2.4 billion miles | ~ 2700 |
| Mass | -- | -- |
| Surface Gravity | -- | -- |
| Surface Composition (by mass) | 74% hydrogen 24% helium 2% everything else |
same |
| Spectral Type | M2 Iae | G2 V |
| 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 a bright red or reddish-orange point of light should be seen.
Mu (μ) Cephei Information:
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This star is huge: if it were placed at our sun’s position, it would extend beyond the orbit of Saturn! (Saturn is ~10 AU from the sun)
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Like many other red giant stars, this is a variable star: its magnitude varies from 3.4 to 5.1. The period of the variation ranges between 730 and 4400 days.
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This star looks very red through the telescope. Sir William Herschel who discovered the planet Uranus) noticed this deep color, and it is often referred to as “Herschel’s Garnet Star.”
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References
| Item | Updated | Notes |
| Coordinates | 2003-09-19 | checks with both SIMBAD and Hipparcos |
| Distance | 2003-09-19 | SIMBAD and Hipparcos give 0.62 mas parallax |
| Actual Brightness | -- | |
| Surface Temperature | 2003-09-19 | from The Flamsteed Collection, M stars range from 2400-3480 K; going with type M2, estimat temp at 3260 K |
| Diameter | 2003-09-19 | from http://www.aavso.org/vstar/vsots/1002.shtml |
| Mass | -- | |
| Surface Gravity | -- | |
| Surface Composition | 2003-09-12 | OK for all stars |
| Spectral Type | 2003-09-19 | SIMBAD and Hipparcos agree |
| Density | -– | |
| Other Information | 2003-09-19 | variable info from aavso site (see diam) garnet star info from http://www.astro.uiuc.edu/~kaler/sow/garnet.html |