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Zeta (ζ) Ursae Majoris
Mizar
Multiple Star System
Right Ascension | 13h 23m 52s | Best Seen | 3/1 - 9/15 |
Declination | 54° 55' 25" | Combined Magnitude | 2.23 |
Apparent Separation | 14.4" | Constellation | Ursa Major |
Actual |
Compared to Sun |
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Distance | 78 ly | -- |
Separation | ~ 47 billion miles | ~ 500 au |
Orbital Period | ~ 5,000 years | -- |
Actual Brightness | -- | 57 / 13 |
Magnitude | 2.25 / 3.87 | -- |
Mass | -- | -- |
Surface Gravity | -- | -- |
Surface Composition (by mass) | 74% hydrogen 24% helium 2% everything else |
same |
Spectral Type | A2 V / A1m | 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 they should see two stars next to each other. One star should be slightly brighter than the other.
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The two stars they see are both called Mizar. Alcor can be seen in the finder some distance from Mizar.
Mizar Information:
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Mizar is the middle star in the handle of the Big Dipper.
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Mizar was the first multiple star discovered. In the early 1600s, a friend of Galileo’s discovered that it was really two stars.
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Each one of the two visible stars in Mizar is actually a multiple star itself!
a. The two stars are spectroscopic multiples, meaning that their companions can’t be seen, only detected through spectroscopic analysis.
b. The brighter star is really two stars so close to each other, they only take about 20 days to orbit each other.
c. The fainter star is really – at least – two stars.
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Another star is near Mizar called Alcor. Alcor can even be seen with the unaided eye on a clear, dark night.
a. Alcor is three light years from Mizar, so Mizar and Alcor are not part of the same system. However, Alcor is part of the Ursa Majoris group.
b. Alcor has a total brightness 12 times that of the sun, is magnitude 3.99, and is spectral type A5V.
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References
Item | Updated | Notes |
Coordinates | 2002-08-30 | just tweaked a bit |
Combined Magnitude | 2002-08-30 | OK w/ Scott’s The Flamsteed Collection |
Apparent Separation | 2002-08-30 | http://www.astronomical.org/constellations/uma.html |
Distance | 2002-08-30 | OK w/ SIMBAD and Flamsteed |
Separation | 2002-08-30 | http://www.astro.uiuc.edu/~kaler/sow/mizar.html |
Orbital Period | 2002-08-30 | http://www.astro.uiuc.edu/~kaler/sow/mizar.html |
Actual Brightness | 2002-08-30 | OK w/ Scott’s Flamsteed |
Magnitude | 2002-08-30 | OK w/ Flamsteed |
Mass | -- | |
Surface Gravity | -- | |
Surface Composition | 2003-01-06 | OK for all stars |
Spectral Type | 2002-08-30 | OK with SIMBAD |
Density | -- | |
Other | 2002-08-30 | Item 2: http://leo.astronomy.cz/mizar/article.htm Item 3b,c: http://www.astro.uiuc.edu/~kaler/sow/mizar.html |