Scorpius;The Scorpion; by Kim Touzel
In ancient mythology the Scorpion’s sting killed Orion the Hunter and Orion can still be seen fleeing as he sets below the horizon in the west as Scorpius rises in the east.
The Scorpion is a distinct constellation in our winter sky. There are an abundance of objects to observe in this brilliant constellation – one of my favourites for binoculars as well as small telescopes.
Antares: alpha (α) Scorpii the brightest star in Scorpius marks the heart of the scorpion. Antares means rival to Mars and is a 1st magnitude red supergiant which is similar in appearance to Mars. It is easily distinguished in the Scorpion due to its brightness and colour…it appears quite orange in binoculars. Antares is a double star. Antares A mag 1.2 and Antares B mag. 5.4, which requires a 150mm (6 inch) scope and good clear seeing conditions to separate it. The companion star Antares B of green-blue colour can be difficult to see in small telescopes due to glare from Antares. (See Photo below)
Graffis/Acrab: beta (β) Scorpii the Scorpion’s claws is another double star 2.6 and 4.9 mag.; these blue-white stars can be separated in small telescopes.
Shaula: lambda (λ) “the sting” is a 1.6 mag. Blue – white star, a useful landmark to find surrounding star clusters as we will see.
Mu Scorpii: (μ) is a naked eye double.
Nu Scorpii: (ν) below beta is a quadruple or double-double star. It can be seen as a wide double with powerful binoculars or a small telescope. Of 4.0 and 6.3 mag., a 75mm and larger telescope at high magnification show the fainter star as a double of mag. 6.8 and 7.8. The brighter star a closer double of 4.3 and 6.8 mag. requires at least a 150mm scope to separate it.
M4: NGC 6121 is a nice globular cluster, approximately 10 billion years old, with an overall brightness of 6th magnitude situated approximately 1° from Antares which can easily be seen with binoculars (a 100mm telescope can resolve some stars, a larger scope will resolve more). With binoculars the cluster appears bright and round. I could not see it with the naked eye due to brightness from Antares. Stephen O’Meara describes the cluster as a “cat’s eye” with the ridge running across the sphere resembling the pupil.
M6: NGC 6405 is my favourite open cluster. The 50 milliion year old “Butterfly Cluster” (see fig.1) with stars from 7 to 10th magnitude contains more than 330 stars, approximately 110 of 11th magnitude or brighter and is located near “Shaula” the sting of the scorpions tail. M6 has an overall brightness of around 4th magnitude and can be seen as a puff of smoke with the naked eye which makes it easy to find and view with binoculars and a telescope. The butterfly pattern can be clearly seen even in small telescopes. See if you can find the brightest star in the cluster BM Scorpii an orange varible which fluctuates between 5.5 to 7 magnitude over 850 days. It marks the north-western tip of the butterfly’s wing. You may even find it with your naked eye.
M7: NGC 6475. About 220 million years old, it is one of the oldest clusters. A larger open cluster than M6, it is easily seen with the naked eye. It contains approximately 80 stars, all brighter than 10th magnitude, which are more golden in colour than the blue-white stars of M6. A very good open cluster to view with binoculars – it is quite spectacular even through my small 8 x 25 Nikon’s. A wide field is best to view it through a telescope.
M19: In neighbouring Ophiuchus is a bright globular cluster of 6.8th magnitude worth exploring while we are observing in this region of the sky. It is one of the most elongated globular clusters. I found it difficult to see with the naked eye, however was easily located with binoculars using Antares as a landmark. Through your telescope does it appear longer N/S than E/W?
M62: NGC 6266, also in Ophiuchus is a 6.7 magnitude globular cluster near M19. The eastern half of the cluster appears brighter than the western. The core of the cluster appears to flicker. Use Epsilon Scorpii as a landmark to find this interesting cluster.
M80: NGC 6093, is a 7.3 magnitude globular cluster visible in binoculars or small telescopes. It has the appearance of the fuzzy head of a comet. It is approximately half way between alpha (Antares) and beta (Graffias) Scorpii, a tiny globular cluster with a dense core. In 1860 a 7th magnitude nova (T-Scorpii) flared from its centre.
NGC 6302: This is a 9.5 magnitude bi-polar planetary nebula also known as “The Bug Nebula” in the region of the scorpion’s tail. It is elliptical or spindle-shaped and bluish in colour. With good seeing conditions it should be visible with a 7.5 cm (3 inch) telescope.
I am sure will enjoy your observations of Scorpius – there are many hours of observing here with many more objects to see than those mentioned above. After taking in this spectacular site in the sky with your naked eye, have a scan around with your binoculars and see how many star clusters you can find.
Once you have found them with binoculars you will more easily identify them with your naked eye. Then you will be amazed at how much more you see once you point your telescope to the sky. If you do not have a telescope at home, come out to our next meeting night and we can all explore Scorpius together.
Sources used: Collins Pocket Guide, Stars & Planets 1993; The Messier Objects – Stephen O’Meara 1998; Hartung’s Astronomical Objects for Southern Telescopes, 2nd Edition 1995.