A Tour of the Messier Catalog ~~ in ~~ Eight Spellbinding and Enlightening Episodes ~~ This Being Episode Six ~~ Voyage to the Center of the Galaxy
M11 Open Cluster Constellation Scutum 18 : 51.1 (h:m) -06 : 16 (deg:m) 6.0 (kly) 6.3 (mag) 14.0 (arc min) Wild Duck Cluster One of the richest and most compact open clusters About 3,000 stars Brian Kimball An observer in the center of the cluster would see about 40 stars from 3 to 50 times brighter than Sirius in the night sky! And several hundred 1 st magnitude!
M26 - Open Cluster Constellation Scutum 18 : 45.2 (h:m) -09 : 24 (deg:m) 5.0 (kly) 8.0 (mag) 15.0 (arc min) Tight, bright cluster of about 90 100 stars Has a small, 2 circular dark gap in the center most probably intervening dark matter Brian Kimall NOAO/AURA/NSF
M16 Open Cluster Constellation Serpens 18 : 18.8 (h:m) -13 : 47 (deg:m) 7.0 (kly) 6.4 (mag) 7.0 (arc min) Cluster is associated with the Eagle Nebula Early observers didn t detect the nebula, only the cluster! A small scope will reveal about 20 stars in the cluster, which were formed from the nebula NOAO/AURA/NSF Burnham also calls it the Star- Queen Nebula see the dark throne in the center with the Queen sitting on it? Nebula was subject of the famous Gas Pillars photo from Hubble
M17 Emission Nebula Constellation Sagittarius 18 : 20.8 (h:m) -16 : 11 (deg:m) 5.0 (kly) 6.0 (mag) 11.0 (arc min) Also called the Swan or Horseshoe or Omega Nebula Both emission and reflection nebula Visually, you can see a loop off of the main bar that makes it look like an Omega shape, or a swan s neck. NOAO/AURA/NSF
Joseph Liu
Brian Kimball
M18 Open Cluster Constellation Sagittarius 18 : 19.9 (h:m) -17 : 08 (deg:m) 4.9 (kly) 7.5 (mag) 9.0 (arc min) Very loose cluster, only about 20 stars And because these are hot, bright stars, it is a very young cluster, only about 30 million years old NOAO/AURA/NSF
M24 Star Cloud Constellation Sagittarius 18 : 16.9 (h:m) -18 : 29 (deg:m) 10.0 (kly) 4.6 (mag) 90.0 (arc min) The Sagittarius Star Cloud Located between the Swan Nebula M17, and the Lagoon Nebula M8 A very rich 2 x 1 field near the galactic center NOAO/AURA/NSF Contains the open cluster NGC 6603, and is viewed through gaps - or a hole in the intervening dust clouds Lies in the next spiral arm in towards the center of the galaxy the Sagittarius-Carina Arm
M25 Open Cluster Constellation Sagittarius 18 : 31.6 (h:m) -19 : 15 (deg:m) 2.0 (kly) 4.6 (mag) 32.0 (arc min) A bright cluster, but did not get included in the General Catalog of John Herschel, so it is the only Messier object that does not have an NGC ID, only an IC or Index Catalog - number Contains about 50 stars brighter than 12 th magnitude NOAO/AURA/NSF
M23 Open Cluster Constellation Sagittarius 17 : 56.8 (h:m) -19 : 01 (deg:m) 2.15 (kly) 6.9 (mag) 27.0 (arc min) A bright, rich, irregularly shaped cluster One of Messier s authentic discoveries Contains about 150 members, and is about 200 million years old NOAO/AURA/NSF Many different lines and shapes can be traced out with the brighter stars
M21 Open Cluster Constellation Sagittarius 18 : 04.6 (h:m) -22 : 30 (deg:m) 4.25 (kly) 6.5 (mag) 13.0 (arc min) Fewer than 60 stars, but concentrated in the center Less than a degree from the Trifid Nebula Very young less than 5 million years NOAO/AURA/NSF
M20 Emission Nebula Constellation Sagittarius 18 : 02.6 (h:m) -23 : 02 (deg:m) 5.2 (kly) 9.0 (mag) 28.0 (arc min) The famous Trifid Nebula Contains both emmission (red) and reflection (blue) nebulosity Named by John Herschel due to the trisecting dark dust lanes These dark nebula were classified by Barnard as Barnard 85 Brian Kimball The Barnard catalog is a very interesting list of dark nebula in the plane of the Milky Way Lies 2 NW of its large neighbor, the Lagoon Nebula
M8 Open Cluster & Emission Nebula Constellation Sagittarius 18 : 03.8 (h:m) -24 : 23 (deg:m) 5.2 (kly) 6.0 (mag) 90x40 (arc min) The famous Lagoon Nebula Another mix of star formation, star clusters, gas and dust a very active stellar nursery! The young open cluster component is NGC6530 NOAO/AURA/NSF The bright center of the Lagoon is called the Hourglass Nebula due to the shape of the foreground dust clouds Also contains globules of protostellar clouds about 10,000 AU in diameter!
Somebody named Olivier in Italy from the internet
M22 Globular Cluster Constellation Sagittarius 18 : 36.4 (h:m) -23 : 54 (deg:m) 10.4 (kly) 5.1 (mag) 32.0 (arc min) Probably the 1 st globular cluster ever discovered Easy naked-eye cluster, brighter than the Hercules cluster M13 The mighty Omega Centauri and 47 Tucanae are the only brighter globulars NOAO/AURA/NSF One of the closest at a little over 10,000 LY One of only 4 globulars known to contain a planetary nebula
M28 Globular Cluster Constellation Sagittarius 18 : 24.5 (h:m) -24: 52 (deg:m) 18.3 (kly) 6.8 (mag) 11.2 (arc min) Smaller and more compressed than M22 Slightly elliptical in shape Intervening Milky Way dust obscures its brightness by about 2 ½ magnitudes One of the more compact and denser globular clusters NOAO/AURA/NSF
M69 Globular Cluster Constellation Sagittarius 18 : 31.4 (h:m) -32 : 21 (deg:m) 29.7 (kly) 7.6 (mag) 9.8 (arc min) One of the smaller and fainter of the Messier globulars Similar to its neighbor, M70, both discovered on the same night One of the metal-richest globulars, indicating old age Only 6200 LY from the Galactic Center NOAO/AURA/NSF
M70 Globular Cluster Constellation Sagittarius 18 : 43.2 (h:m) -32 : 18 (deg:m) 29.3 (kly) 7.9 (mag) 8.0 (arc min) A physical neighbor of M69 about the same distance away from us and 2 east of M69 Close in size and magnitude to M69 Has a very dense core NOAO/AURA/NSF Became famous in 1995 when Comet Hale-Bopp was discovered while Alan Hale and Thomas Bopp were observing M70
M54 Globular Cluster Constellation Sagittarius 187 : 55.1 (h:m) -30 : 29 (deg:m) 87.4 (kly) 7.6 (mag) 12.0 (arc min) Easternmost of a row of 3 Messier globulars in the base of the Sagittarius Teapot asterism Small and bright with an intense core 3 times further away than M69 and M70 NOAO/AURA/NSF Discovered to be not in the Milky Way after all, but associated with the recently discovered Sagittarius Dwarf Elliptical Galaxy a member of the Local Group of galaxies!
M55 Globular Cluster Constellation Sagittarius 19 : 40.0 (h:m) -30 : 58 (deg:m) 17.3 (kly) 6.3 (mag) 19.0 (arc min) Large cluster, about 2/3 of the Moon s diameter Fairly loose visually One of the nearer clusters at about 17,000 LY NOAO/AURA/NSF
Credits & Acknowledgements: Star Maps: Text: Photos: Night Vision, courtesy of Brian Simpson Burnhams Celestial Handbook National Optical Astronomy Observatory SEDS University of Arizona Brian Kimball National Optical Astronomy Observatory