Showpiece Deep-Sky Objects of Mid-Winter

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Showpiece Deep-Sky Objects of Mid-Winter

by Dave Mitsky

During winter, the Earth faces towards the Perseus Arm of the Milky Way at night. As a consequence, open clusters and nebulae are plentiful, while few globular clusters and galaxies can be seen.

For your observing pleasure, here are ten noteworthy deep-sky objects that are currently well-placed in the evening sky:

1. M42, or the Great Orion Nebula (Orion, NGC 1976, magnitude 5.0, angular size 65' x 60'). M42, the second brightest emission nebula in the heavens, is one of the most famous and frequently observed celestial objects. Located approximately 1600 lights years from the Earth, this gigantic cloud of gas and stellar nursery is some 30 light years in diameter and is surpassed only by the southern hemisphere’s Eta Carinae Nebula (NGC 3372). M42's nebulosity glows a pale green-white in most telescopes. Some observers have reported seeing ruddy hues in the outlying “wings�? of M42. Under good seeing, six stars (the fifth to seventh magnitude A, B, C, D, and the eleventh magnitude E and F) of the young, trapezoid-shaped multiple star known as the Trapezium (Theta 1 Orionis) are visible. (The Trapezium is actually an open cluster in the making.) There have been reports of as many as nine stars being detected through telescopes in the 20-inch range. Other areas of interest are the bright central area known as the Huygenian Region and the dark Fish’s Mouth that protrudes into it. Comma-shaped M43 lies directly north of the Great Orion Nebula and is actually a detached part of it. M42, Theta 2 Orionis, 42 Orionis, 45 Orionis, and the attractive binary star Iota Orionis comprise the asterism known as the Sword of Orion, a most spectacular binocular object.
2. M35 (Gemini, NGC 2168, magnitude 5.1, angular size 28'). M35 is one of the best open clusters in the Messier Catalogue and is a splendid object for both binoculars and telescopes. M35 consists of several hundreds of stars and is approximately 2800 light years away. About 0.5 degree to the southwest of M35 is the faint open cluster, NGC 2158 (magnitude 8.6, angular size 5�?). This powdery splash of starlight lies some 16,000 light years distant and is sometimes mistaken for a comet. NGC 2158 can be viewed with an 80mm aperture from a dark site.
3. M46 (Puppis, NGC 2437, magnitude 6.1, angular size 27'). This very rich and attractive open cluster is situated 1.5’ east of the brighter but coarser open cluster M47. M46 has over 100 members and is believed to be located 5000 light years from the Earth. Part of the attraction of M46 is an unrelated annular planetary nebula, NGC 2438, that is some 65�? in diameter and is “superimposed�? upon the northeast section of M46.
4. M41 (Canis Major, NGC 2287, magnitude 4.5, angular size 38'). Situated some 4 degrees south of Sirius, this large, bright, and coarse open cluster can be seen with the naked eye. A conspicuous orange colored K-type giant star is present in the central portion of the cluster along with an asterism resembling the keystone of the constellation of Hercules. M41 consists of approximately 100 stars and lies at a distance of 2350 light years.
5. NGC 2362 (Canis Major, magnitude 4.1, angular size 8'). NGC 2362 is a bright and compact open cluster that consists of several dozen stars, including the fourth magnitude triple star Tau Canis Majoris. It is some 5000 light years distant and is one of the youngest known open clusters. Due to the interesting phenomenon known as the persistence of vision, NGC 2362 has been nicknamed the Mexican Jumping Bean Cluster. (Gently tap your telescope and watch what happens.) It is also known as the Tau Canis Majoris Cluster.
6. NGC 2237-9, or the Rosette Nebula (Monoceros, magnitude ~6.0, angular size 80' x 60'). This large emission nebula surrounding the young open cluster NGC 2244 requires dark skies, a rich-field telescope, and a narrowband nebula filter to be fully appreciated, although it can be seen with a binocular if conditions are excellent. The Rosette Nebula is over 5400 light years from the Earth and is one of the largest and most massive nebulae in the Milky Way. Shining at fourth magnitude, NGC 2244 is an easy binocular target and can also be seen with the unaided eye.
7. NGC 2392, or the Eskimo Nebula (Gemini, magnitude 8.3, angular size 45�?). Also known as the Clown-Face Nebula, this blue colored planetary nebula is situated to the southeast of Delta Geminorum. The tenth magnitude central star is easily visible with direct vision, while the bright central disk, which spans 15�?, becomes more prominent with averted vision.
8. NGC 2261, or Hubble’s Variable Nebula (Monoceros, magnitude 10 to 13, angular size 3.5' x 1.5'). NGC 2261 is an interesting emission and reflection nebula that was the first object to be photographed through the 200-inch Hale telescope at Mount Palomar. This nebula surrounds the variable star R Monocerotis and changes in brightness along with the star. NGC 2261 strongly resembles a fan-shaped comet. It is located about 3000 light years from us.
9. NGC 2169 (Orion, magnitude 5.9, angular size 5’ x 7'). This bright but sparse open cluster consists of about 30 stars, 14 of which form an unmistakable number 37. The binary star Struve 848 is located in the “7�? and is the cluster’s lucida, or brightest star.
10. NGC 2264, or the Christmas Tree Cluster (Monoceros, magnitude 3.9, angular size 20'). The bright Christmas Tree Cluster resembles its namesake and is a fine binocular object. The trunk begins with the fifth magnitude variable star S (15) Monocerotis. The dark Cone Nebula, an extremely difficult visual object, is located just south of a sixth magnitude star at the top of the tree. Some 40 stars inhabit this cluster.

Other mid-winter objects that are well worth a look include the quintuple star Sigma Orionis and nearby triple star Struve 761, the beautiful binary star that is sometimes called the Winter Alberio h3945 (Canis Major), and the striking triple star Beta Monocerotis; the ruddy-hued carbon stars W Orionis and R Leporis (Hind’s Crimson Star); the globular cluster M79 (Lepus); the open clusters M50 (Monoceros), M93 (Puppis), NGC 2129 (Gemini), NGC 2232 (Monoceros), NGC 2301 (Monoceros), NGC 2311 (Monoceros), NGC 2420 (Gemini), NGC 2451 (Puppis), NGC 2477 (Puppis), and NGC 2539 (Canis Major); the emission nebulae 2024 (Orion), popularly known as the Flame or the Tank Tracks Nebula, and NGC 2359 (Canis Major), which is nicknamed Thor’s Helmet or the Duck Nebula; the planetary nebulae NGC 2022 (Orion), NGC 2371-2 (Gemini), and NGC 2440 (Puppis); and the bright reflection nebula M78 (Orion).

So bundle up, grab your binoculars or telescope, and behold some of the treasures of this chilly season.