NGC 2976 does not look like a typical spiral galaxy, as this NASA Hubble Space Telescope image shows.
In this view of the oddball galaxy's inner region, there are no obvious spiral arms. Dusty filaments running through the disk show no clear spiral structure. A raucous interaction with a neighboring group of hefty galaxies stripped away some gas and funneled the rest to the galaxy's inner region, fueling star birth about 500 million years ago. At the same time, the galaxy's outer regions stopped making stars because the gas ran out. Now, the inner disk is almost out of gas as new stars burst to life, shrinking the star-formation region to a small area of about 5,000 light-years around the core.
Astronomers pieced together the galaxy's star-formation story with the help of Hubble's sharp vision. The galaxy's relatively close distance to Earth allowed Hubble's Advanced Camera for Surveys (ACS) to resolve hundreds of thousands of individual stars. What look like grains of sand in the image are actually single stars.
Studying the individual stars allowed astronomers to determine their color and brightness, which provided information about when they formed. Based on this analysis, the astronomers reconstructed the star-making history for large areas of the galaxy.
The blue dots in the image are fledgling blue giant stars residing in the remaining active star-birth regions. NGC 2976 resides on the fringe of the M81 group of galaxies, located about 12 million light-years away in the constellation Ursa Major.
The observation is part of the ACS Nearby Galaxy Survey Treasury (ANGST) program. Data for the image were taken Dec. 27, 2006, to Jan. 10, 2007.
Credits
NASA, ESA, and J. Dalcanton and B. Williams (University of Washington, Seattle)| About The Object | |
|---|---|
| Object Name | NGC 2976 |
| Object Description | Spiral Galaxy |
| R.A. Position | 09h 47m 15.45s |
| Dec. Position | 67° 54' 59.0" |
| Constellation | Ursa Major |
| Distance | This image is 2.8 arcminutes (9,800 light-years or 3,000 parsecs) wide. |
| About The Data | |
| Data Description | This image was created from HST data from proposal : J. Dalcanton (University of Washington, Seattle) and collaborators. |
| Instrument | HST>ACS/WFC |
| Exposure Dates | December 27, 2006 - January 10, 2007, Exposure Time: 1.3 hours |
| Filters | F475W (B), F606W (V), and F814W (I) |
| About The Image | |
| Color Info | The image is a composite of separate exposures made by the ACS/WFC instrument on the Hubble Space Telescope. Three filters were used to sample broad wavelength ranges in the near infrared. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: Blue: F475W (B) Green: F606W (V) Red: F814W (I) |
| Compass Image |  |
| 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. |
