NGC 5139 THE GREAT OMEGA CENTAURI 3 PART ZOOM (1-3).
Photo By: Joaquin Polleri & Ezequiel Etcheverry from the Observatorio Panameño en San Pedro de Atacama. CLICK for full size photo and links below.
This is going to be a 3-photo post on the mighty Omega Centauri. In this series I will use three photos to illustrate this, the most massive of all the clusters. Each of the three we will get closer and closer in to the core region. Please let me know if you dig it, if so I will create more that are similar from time to time.
NGC 5139, Omega Centauri is the largest, most massive star cluster in our galaxy (It’s almost as large as the Full Moon in the night sky). It was discovered by Edmond Halley in 1677 (Yes, THAT Halley) though it had been observed and documented before that. In 150AD Ptolemy described and cataloged this object as a star on the horse’s back or “Quae est in principio scapulae”. Johann Bayer used Ptolemy’s data and designated this object “Omega Centauri” in his 1603 publication Uranometria. Re-discovered by Halley in 1677, he didn’t publish the findings until 1715 as part of his list of six “Luminous spots or patches” in the Philosophical Transactions of the Royal Society.
Globular Clusters are mysterious, beautifully spherical collections of stars that reside above and below the plane of the galaxy and orbit, for the most part near the region of the galactic core (The Milky Way contains about 150-200 globulars). Cataloged as NGC 5139 or Caldwell 80, Omega Centauri is by far the brightest most massive and luminous globular cluster in the night sky, packing in upwards of 10 million stars. It resides in the southern hemisphere constellation of Centaurus and on occasion during a few select times of the year can be viewed in northern latitudes all the way to the Canadian border. As most globular clusters serve as fossils to the galaxy, Omega Centauri is no different. At an estimated age of about 12 billion years this cluster dates back nearly to the beginning of the universe itself. It contains several million Population II (metal poor) stars and the core region is so densely packed with stars that on average, stars are only one-tenth of a light year from each other. Observations made by the Hubble Space Telescope and the Gemini Observatory in Chile (Gemini South) have gleaned evidence that at the core of Omega Centauri lies an intermediate sized black hole. That along with the fact that so many stars within Omega Centauri are of different ages and chemical compositions it has been thought that Omega Centauri is a remnant of a now dispersed dwarf galaxy similar to the two Magellanic Clouds or the former core of a now dead galaxy that was absorbed into the Milky Way billions of years ago. Not to mention it’s 10 times the size of any other globular cluster.
Only during certain times of the year (Jan-June) can northern latitude sky watchers around mid-North America catch a glimpse of it low on the horizon. Some have even been able to spot it in Canada near the US border.
RANDOM FACT: The southern hemisphere star “Kapteyn’s Star” (SAO 217223) in the constellation Pictor, a red dwarf, is believed to have originated in Omega Centauri.
NAME: Omega Centauri, NGC 5139, Caldwell 80.
WHAT IS IT?: Globular Star Cluster; by far the largest in the galaxy.
HOW BIG IS IT?: Approximately 150 light years in diameter and its mass is approximately 4 million solar masses. On the night sky it’s almost as large as the Full Moon.
HOW FAR AWAY IS IT?: Approximately 17,000 light years distant according to NASA’s Hubble Team.
HOW OLD IS IT?: An estimated 12 billion years old.
APPARENT MAGNITUDE?: A naked eye bright 3.9 or +3.9.
WHERE IS IT? (General): Southern Hemisphere Constellation of Centaurus.
WHERE IS IT? (Exact RA/DEC): RA 13h 26m 47.28s / DEC −47° 28′ 46.1″.
NASA APOD page for this photo: http://apod.nasa.gov/apod/ap130501.html
WHERE IS M13 is a free program that gives you the galaxy and all of its features in 3D: http://www.thinkastronomy.com/M13/