Cassiopeia & Centaurus

A Selection of Double Stars in Cassiopeia

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Eta Cassiopeia a true binary system which is only 19.4 light years distant and is easily resolved in small telescopes. The orbit of the secondary star is highly eccentric which brings it as close to the primary star as 36 A.U. which is comparable to the distance of Neptune to our Sun.
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AR Cass has the appearance of a small cluster and the proper motions of members A-C-D-F & G suggest a common origin. AR Cass is closest to us at 573 LY while components C-D-F-G vary in distance from 650 to 740 LY. STF 3022 A-B is a physical pair 1,000 LY distant.
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The physical pair Leonard 55 are members of the open cluster of NGC 7790 in the constellation of Cassiopeia. It is the only known pair in the Milky Way where both components of a binary system are Classical Cephid Variable Stars. Depending on when it is viewed either one or the other may take pride of place as being the brighter “Primary Star”.
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Visible in small scopes as a beautiful triple system, Iota Cass is actually composed of five stars. What we see as the bright “A” component is actually made up of two stars – mags 4.6 & 8.5 – separated by 0.7″. The diminutive C component is also made up of two stars with a separation of only 0.4″.
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Though only an optical association the striking Gold-Blue color contrast makes this a favorite target in small telescopes and begs comparison with the better known Beta Cygni system (Alberio) in Cygnus.
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The optical pair STF 121 shares this view with a duo of carbon stars, KISO C1-163 & C1-165. Carbon Stars tend to be solitary objects but as far as I can tell this is the tightest grouping of Carbon Stars that I am aware of. This distant pair (11,440 LY) with a separation of 39 arc-sec, gives us a “true” separation of approximately 2 LY. This is nearly half the distance to our nearest stellar neighbor Proxima Centauri. So we are are probably safe to say that they are not gravitationally bound, but they do appear to share similar proper motions.
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VYS 2 is a nearby triple system composed of three Red Dwarf stars. There is some evidence that the B component may also have a low-mass companion (0.15 Msun) orbiting it.

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A Selection of Double Stars in Centaurus

Centaurus is a large constellation best viewed from from the southern hemisphere or locations more southerly than Colorado. Its northern boundary however does manage to rise 10-15 degrees above my southern horizon at various times throughout the year allowing me the opportunity to capture a few objects from this colorful and star-rich region.

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