α Serpentis

Alpha Serpentis is ‘Unukalhai’, the Serpent's Neck. In the Middle Ages the star was also known as ‘Cor Serpentis’. the Serpent's Heart.

This yellow (or golden) giant is about half-way down the western portion of the constellation, 9º south of beta: binoculars.

Delta Serpentis is a binary (Struve 1954) of two yellow stars; AB: 4.2, 5.2; 172º, 4.0" with an orbit of 3168 years.


If you place alpha on the southwest edge of your glasses and move two full fields southwest, you'll be in the vicinity of M5, a splendid globular gluster of over half a million stars tightly grouped.
     With an apparent magnitude of 5.7, with excellent sky conditions the cluster is just visible to the naked-eye; the larger the telescope the more enjoyment this cluster will bring, with a blueish central core surrounded by a pale yellow outer region. Many observers rate this cluster as one of the finest in the Northern Hemisphere. It's thought to be more than ten billion years old.

Two binaries accompany M5 in this field, 5 Ser and 6 Ser:
      5 Ser is a multiple system (Struve 1930) of faint components:
           5 SerAB: 5.1, 10.1; 36º, 11.5".
      6 Ser (BU 32): 5.5, 8.8; 22º, 3.4".


Crossing over now to Serpens Cauda, from alpha Serpentis move east 30º (2 hours of Right Ascension) where you will find beta Ophiuchus. Placing beta Oph on your western edge, move three more fields east to theta Serpentis.

Click on theta on the map to continue.

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