Resembling a dazzling display of holiday lights, this crowded field of stars lies in the heart of a giant stellar swarm known as Omega Centauri. A collection of nearly 10 million stars in all, Omega Centauri is the largest of about 150 "globular clusters" in the Milky Way. It's big enough that stargazers can spot it by eye from the southern hemisphere or from low northern latitudes.
The stars' colors give us information about them. Bright blue stars are old, hot stars that are now burning helium instead of hydrogen in their cores. Bright red stars are cool giants that are heading into old age. Dimmer red stars are cool dwarfs destined to live for a long, long time. White stars are typically middle-aged, average stars.
The stars move around the center of Omega Centauri seemingly at random, like a swarm of bees. But because they are so far away, roughly 17,000 light-years from Earth, it takes years for us to notice any change in their positions. Even then, astronomers need the power of Hubble to see these changes. The center of Omega Centauri is so crowded, telescopes here on the ground have no hope of spotting individual stars there, because Earth's atmosphere blurs the view.
Astronomers Jay Anderson and Roeland van der Marel of the Space Telescope Science Institute analyzed archived Hubble observations of the stars at the center of Omega Centauri taken over four years, from 2002 to 2006, with the Advanced Camera for Surveys. They compared these sets of Hubble observations to measure the motions of more than 100,000 stars in the cluster. They then used the measurements to predict where the stars will go over the next 10,000 years.
Earlier research had suggested that there might be a black hole at the center of Omega Centauri. This seems unlikely, though, based on Anderson and van der Marel's study of the Hubble observations. The stars at the center of Omega Centauri are not traveling as they would if a massive black hole were gravitationally tugging on them, shepherding their movements.
Constellation: Centaurus
Distance: 16,000 light-years (4,800 parsecs)
Instrument: Advanced Camera for Surveys and Wide Field Camera 3/UVIS
Image Filters: F225W (U), F275W (U), F336W (U), F438W (B), F606W (V), F814W (I)
| About The Object | |
|---|---|
| Object Name | Omega Centauri, NGC 5139 |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
