Double star

Sekarang aku tengah focus study double star  (tapi 2/3 harini cuaca tak best sangat, so jarang bleh tengok guna telescope…  tapi takper, study dulu, yelar bintang2 tu still ader di situ… tak ke mana haha… ).. aku suka refer article  “Seeing Double by James Mullaney” yg cerita beginner guide utk tengok double star even using cheap telescope atau binocular. antara double star yg boleh dicari berdasarkan guide tersebut adalah seperti berikut:

• Big Dipper –> Mizar (the brighter one) and Alcor.
• The Double-Double (Epsilon Lyrae) = using >100x magnification
• Alya (Theta Serpentis) = best using 30x magnification
• Albireo (Beta Cygni) = best using  30x magnification
• Omicron-1 Cygni = best using 30x magnification
• Gamma Delphini = best using 75x magnification
• Enif (Epsilon Pegasi) = best using 50x magnification
• Delta Cephei = best using 30x magnification
• Almach (Gamma Andromedae) = best using 75x magnification

More info:

“Seeing Double” by James Mullaney,
Sky & Telescope – The Essential Magazine of Astronomy, http://www.skyandtelescope.com/observing/objects/doublestars

http://en.wikipedia.org/wiki/Double_star

In observational astronomy, a double star is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope.

There are three types of paired stars:

• optical doubles — unrelated stars which appear close together through chance alignment with Earth
• visual binaries — gravitationally-bound stars which are separately visible with a telescope
• non-visual binaries — stars whose binary status was deduced through more esoteric means such as occultation, spectroscopy, or anomalies in proper motion.

http://en.wikipedia.org/wiki/Multiple_star

A multiple star consists of three or more stars which appear from the Earth to be close to one another in the sky. This may result from the stars being physically close and gravitationally bound to each other, in which case it is physical, or this closeness may be merely apparent, in which case the multiple star is optical.