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Home , Terzan 7

“GLOBULAR CLUSTERS? IF YOU’VE SEEN ONE, YOU’VE SEEN’EM ALL.” RIGHT?

WRONG! • Globular clusters — large balls of stars that orbit the centers of galaxies but can lie very far from them — remain one of the biggest cosmic mysteries THE FORMER “PARTY LINE’ classical clusters • Unl ~7 years ago, globular clusters were: – simple stellar populaons – products of a single burst of star formaon – uniform distribuon – uniform He abundance – origin: coeval, rapidly formed within an isolated gas cloud during the early stages of evoluon H-R diagram of M15 • Now research has since shown that many of the Milky Way's globular clusters had far more complex formaon histories and are made up of at least two disnct populaons of stars. M22 (2), NGC 2808 (3), NGC 1851 (2) et al., hp://imagizer.imageshack.us/a/img593/7066/5ssb.png

The Sagiarius Stream is a long, star stream that wraps around the Milky Way galaxy. It consists of dally stripped stars from the Sagiarius Dwarf Ellipcal Galaxy.

– M 54 – Arp 2 – Terzan 7 – Terzan 8 – Pal 1 – Terzan 7 Pal 2 – Pal 12 – – Whing 1

The orbit (red line) of in the halo of our Milky Way as reconstructed from the dal tails and the known posion, distance and radial velocity of the cluster. The image used to illustrate the Milky Way Galaxy is courtesy of the Hubble Heritage project (STScI/NASA). Pal 5 is ~2° south of M5 • 1) HOW TO ENHANCE YOUR VIEWING OF GLOBULAR CLUSTERS a) compare GCs of different concentraon classes b) resoluon? V(HB) c) special features planetary nebulae star strings 2) PUSH YOUR SCOPE TO ITS LIMITS a) faint Milky Way GCs b) extra galacc (non Milky Way) GCs 42 GCs in the Observers Handbook Astronomy March 2014 Tom’s list with Constellaon, page in Uranometria and Class added

et al, 113 total CLASSES • MESSIER GCs • I (1) M75 VII (2) M10, M22 • II (2) M2, M80 VIII (3) M9, M14, M19 • III (1) M54 IX (3) M4, M12, M72 • IV (4) M15, M28, M62, M92 X (3) M56, M68, M107 • V (7) M5, M13, M30, M53 X-XI (1) M71 • M69, M70, M79 XI (1) M55 • VI (1) M3

A Classificaon of Globular Clusters Authors: Shapley, H. & Sawyer, H. B. Journal: Harvard College Observatory Bullen No. 849, pp.11-14

M 75 (Class 1) vs M55 (Class 11) M 53 (V) vs NGC 5050 (XI)

Class XII 47 Tuc (Milky Way) vs NGC 121 (SMC) two “extragalacc” GCs have NGC designaons NGC 121 (SMC) and NGC 1049 () Star “strings” are apparent in some GCs

M4 Hubble image ESO 456-38 (Djorg 2) ESO 456-38 (DJORG 2) approx 2.5° N of γ Sgr (tip of tea kettle) toward the centre through the plane of the Milky Way

Pease 1 in M 15 GJJC 1 in M22 THE ULTIMATE CHALLENGE ?? • WHY LOOK FOR SMALL EXTRAGALACTIC (USUALLY , BUT NOT ALWAYS, STELLAR) GLOBULAR CLUSTERS ?

– FOR THE HUNT AND CHASE – FOR THE CHALLENGE – ADD NEW OBJECTS TO YOUR “LIFE LIST” – IT’S SATISFYING TO PUSH TO THE LIMITS OF YOUR TELESCOPE – WHY DO WE LOOK AT PLUTO? IT LOOKS JUST LIKE A VERY FAINT FIELD STAR

BRIGHTEST GC IN 8 NEARBY GALAXIES

hp://www.astronomy-mall.com/Adventures.In.Deep.Space/gcextra.htm M31 GCs G76 and G119 G76 appears fuzzy at high mag and is the easiest M31 GC to locate

G1 in M31 G1 is the largest GC known o ~2.3 SW of M32

SM20” M 110 GCs M 33 C39 M 33 M33 globular U49 (mag 16.25v) A very faint cluster appearing as a "star" just northeast of a small triangle of 16th to 17th magnitude stars. This was visible > 75% of the me with adverted vision. Brian Skiff B324 is the brightest individual star in M33

by Steve Golieb hp://www.astronomy- Breath on a Mirror; Astronomy blog by Jaakko mall.com/Adventures.In.Deep.Space/Resolving Saloranta hp://fdsa-blog.blogspot.ca/ the Brightest Star in M33.htm 2013/08/extragalacc-objects-in- triangulum.html NGC 1049 brightest of 4 visible in the Fornax Dwarf with a medium sized scope • NGC 1049 was discovered by John Herschel at the Cape of Good Hope and described as "like a star 12th magnitude a very lile rubbed out at the edges, a curious lile object and easily mistaken for a star, which, however, it certainly is not." Fornax Dwarf Globulars NGC 1049

MegaStar chart

GO FIND A GLOBULAR CLUSTER END