[LEFT] A GALEX ultraviolet image of the interacting galaxies M81 and M82, which lie 12 million light-years away in the constellation Ursa Major. The gravity from each galaxy dramatically affected the other during their last close encounter, 200 million years ago. Gas density waves rippling around M81 make it a grand design spiral. M82 is undergoing a starburst at its core, creating glowing fingers of hydrogen.
[RIGHT] A Hubble Space Telescope visible light image of bright blue star clusters found along a wispy bridge of gas that was tidally stretched between the two galaxies, and a third companion galaxy not seen in this picture. This is not the place astronomers expect to find star clusters because the density of gas is so low. Turbulence in the gas may have enhanced the density locally to trigger starbirth. The so-called "blue blobs" are clumped together in a structure called Arp's Loop. Hubble reveals the clusters contain the equivalent of five Orion Nebulae. A Hubble plot of the stellar population in the clusters yields an age of approximately 200 million years, which coincides with the epoch of the collision.
Credits
NASA, ESA, and D. de Mello (Catholic University of America/GSFC)| About The Object | |
|---|---|
| Object Name | M81 - M82 Galaxy Group, Arp's Loop |
| Object Description | Galaxy Group |
| Constellation | Ursa Major |
| Distance | 12 million light-years (3.6 Megaparsecs) |
| About The Data | |
| Data Description | The science team comprises D. de Mello (GSFC/Catholic University of America, Washington/JHU), L. Smith (STScI/ESA/University College London), E. Sabbi (STScI), J. Gallagher (University of Wisconsin, Madison), M. Mountain (STScI), and D. Harbeck (University of Wisconsin, Madison). The Hubble image of Arp's Loop was created from HST Proposal: J. Dalcanton (University of Washington). |
| Instrument | GALEX (left) HST>ACS/WFC (right) |
| Exposure Dates | September 22, 2006 (HST, right) |
| Filters | GALEX: Ultraviolet ACS/WFC: F435W (B) and F814W (I) |
| About The Image | |
| Color Info | The HST images are a composite of separate exposures made by the ACS instrument on the Hubble Space Telescope. Two filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: Blue: F435W (B) Green: F435W (B) + F814W (I) 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. |
