[Left] - A view of globular cluster M4 (fourth object in the Messier catalog of star clusters and nebulae). The nearest globular cluster to Earth (7,000 light-years away), and containing more than 100,000 stars, M4 was the target of a Hubble Space Telescope search for white dwarf stars. Ancient red giant stars are predominant in this view from a ground-based telescope. The field is 47 light-years across. The box (right of center) shows the small area that Hubble telescope probed.
[Right] - A Hubble Space Telescope color image of a small portion of the cluster only 0.63 light-years across reveals eight white dwarf stars (inside blue circles) among the cluster's much brighter population of yellow sun-like stars and cooler red dwarf stars. Hubble reveals a total of 75 white dwarfs in one small area within M4, out of the total of about 40,000 white dwarfs that the cluster is predicted to contain. The Hubble results will allow astronomers to refine theoretical predictions of the rate at which white dwarfs cool - an important prerequisite for making reliable estimates for the age of the universe and of our Milky Way galaxy, based on white dwarf temperatures. The image was taken with the Wide Field and Planetary Camera 2.
Credits
Left: Kitt Peak National Observatory 0.9-meter telescope, National Optical Astronomy Observatories; courtesy M. Bolte (University of California, Santa Cruz);Right: Harvey Richer (University of British Columbia, Vancouver, Canada) and NASA
| About The Object | |
|---|---|
| Object Name | M4, NGC 6121 |
| R.A. Position | 16h 23m 35.41s |
| Dec. Position | -26° 31' 31.9" |
| 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. |
