{"id":26832,"date":"2021-11-29T08:57:58","date_gmt":"2021-11-29T08:57:58","guid":{"rendered":"https:\/\/www.skyatnightmagazine.com\/?p=45115"},"modified":"2021-11-29T09:10:26","modified_gmt":"2021-11-29T09:10:26","slug":"orion-a-guide-to-the-hunter-constellation","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/orion-a-guide-to-the-hunter-constellation\/","title":{"rendered":"Orion: a guide to the Hunter constellation"},"content":{"rendered":"

<\/p>

By Paul Money\n \t\t<\/p>

Published: Monday, 29 November 2021 at 12:00 am<\/p>

\n\n

T<\/span>here are few constellations that grab the attention quite like that icon of the winter heavens, Orion. The glittering bright stars, the instantly recognisable \u2018belt\u2019 and the many glowing nebulae scattered within the Hunter\u2019s boundaries all make Orion a wonder to behold on a frosty, dark night.<\/p>\n

But the constellation is also a rich hunting ground for observers and astrophotographers seeking deep-sky targets.<\/p>\n

\""Constellation\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
Constellation of Orion by Zygmunt Szot, Comporta, Portugal. Equipment: Canon PowerShot G7 X, Joby Gorillapod Hybrid Tripod<\/span><\/figcaption><\/div>\n

O<\/span>rion holds something for everyone, whether you enjoy the naked-eye splendour of its stars, want to tour it with a pair of binoculars, peer deeper with a modest telescope or delve into its deepest <\/span>and faintest targets with 10- to 14-inch systems.<\/span><\/p>\n

It is easy to enjoy the view of the Orion Nebula<\/a> alone, but a host of astronomical treasures awaits those willing <\/span>to look a little closer.<\/p>\n

Below we reveal some of Orion\u2019s most striking features and the equipment needed to see them.<\/p>\n

Orion\u2019s Belt<\/strong><\/h2>\n
\""Orions\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
Orions Belt by John Harding, Sheffield, S. Yorkshire, UK. Equipment: Pentax KR DLSR<\/span><\/figcaption><\/div>\n

One part of Orion is particularly recognisable. It comes in the form of just three stars, and is known as Orion\u2019s Belt.<\/span><\/p>\n

\u00a0same colour, quite close together, are virtually the same brightness and form a fairly straight line.<\/span><\/p>\n

The stars, from east to west, are known by their Arabic names of Alnitak (\u2018belt\u2019), Alnilam (\u2018string of pearls\u2019), and Mintaka (\u2018girdle\u2019).<\/span><\/p>\n

Just for interest, if you\u2019ve ever seen any of the wonderful images of a gas cloud in space known as the Horsehead Nebula, then it sits in this part of the sky, just below the Belt star Alnitak \u2013 although you would need a big telescope to see it.<\/span><\/p>\n

Mintaka<\/strong><\/h3>\n
\""Credit:\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
Credit: Pete Lawrence<\/span><\/figcaption><\/div>\n

Mintaka (Delta (\u03b4<\/span>) Orionis) is easy to find. Shining at mag. +2.3, it marks the northwest end of Orion\u2019s Belt, the star\u2019s name deriving from the Arabic for \u2018belt\u2019.<\/p>\n

Sitting 17 arcminutes south of the celestial equator, Mintaka hides a great deal of complexity.<\/p>\n

Observations made by Johannes Franz Hartmann in 1904, using photographs taken at the Potsdam Observatory in Germany, showed Mintaka was a spectroscopic binary star.<\/p>\n

A spectroscopic<\/a> binary shows periodic movement within its component star\u2019s spectral lines.<\/p>\n

Hartmann noticed the Calcium-K line at 393.34 nanometres didn\u2019t show the same periodicity as the Mintakan system and from this he deduced there must be a calcium cloud between us and the star.<\/p>\n

This was the first detection of what\u2019s known as the interstellar medium.<\/p>\n

Mintaka is a complex multiple star, comprising a mag. +6.8 star 52 arcseconds to the north of the primary and a far fainter 14th magnitude star in between.<\/span><\/p>\n

The mag. +2.3 primary is designated A, the 14th magnitude star is B and the mag. +6.8 star C.<\/span><\/p>\n

Delta (\u03b4<\/span>) Orionis A is the spectroscopic binary, an O9.5 II giant (Aa1) and B1 V main sequence star (Aa2) in a 5.73-day orbit.<\/p>\n

A B0 IV subgiant (Ab) sits 0.26 arcseconds from the spectroscopic pair.<\/p>\n

The 14th magnitude companion (B) is a cool star, about 70% the size of our Sun and around 40% as luminous.<\/p>\n

The seventh magnitude companion (C) is another spectroscopic binary comprising an A-type primary and B-type companion in a 30-day orbit.<\/p>\n

Observing Orion with the naked eye<\/strong><\/h2>\n

Allow 30-40 minutes for your eyes to adapt to the dark before you start observing<\/em><\/p>\n

\""Orion\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
Orion by Richard Abels, Rutland, United Kingdom. Equipment: Canon 600D, 18mm lens.<\/span><\/figcaption><\/div>\n

Betelgeuse <\/b><\/a>(Alpha Orionis)<\/p>\n