In the direction of the constellation Canis Major, two spiral galaxies pass by each other like majestic ships in the night. The near-collision has been caught in images taken by NASA's Hubble Space Telescope and its Wide Field Planetary Camera 2.
The larger and more massive galaxy is cataloged as NGC 2207 (on the left in the Hubble Heritage image), and the smaller one on the right is IC 2163. Strong tidal forces from NGC 2207 have distorted the shape of IC 2163, flinging out stars and gas into long streamers stretching out a hundred thousand light-years toward the right-hand edge of the image.
Computer simulations, carried out by a team led by Bruce and Debra Elmegreen, demonstrate the leisurely timescale over which galactic collisions occur. In addition to the Hubble images, measurements made with the National Science Foundation's Very Large Array Radio Telescope in New Mexico reveal the motions of the galaxies and aid the reconstruction of the collision.
The calculations indicate that IC 2163 is swinging past NGC 2207 in a counterclockwise direction, having made its closest approach 40 million years ago. However, IC 2163 does not have sufficient energy to escape from the gravitational pull of NGC 2207, and is destined to be pulled back and swing past the larger galaxy again in the future.
The high resolution of the Hubble telescope image reveals dust lanes in the spiral arms of NGC 2207, clearly silhouetted against IC 2163, which is in the background. Hubble also reveals a series of parallel dust filaments extending like fine brush strokes along the tidally stretched material on the right-hand side. The large concentrations of gas and dust in both galaxies may well erupt into regions of active star formation in the near future.
Trapped in their mutual orbit around each other, these two galaxies will continue to distort and disrupt each other. Eventually, billions of years from now, they will merge into a single, more massive galaxy. It is believed that many present-day galaxies, including the Milky Way, were assembled from a similar process of coalescence of smaller galaxies occurring over billions of years.
This image was created from 3 separate pointings of Hubble. The Wide Field Planetary Camera 2 data sets were obtained by Debra Meloy Elmegreen (Vassar College), Bruce G. Elmegreen (IBM Research Division), Michele Kaufman (Ohio State U.), Elias Brinks (Universidad de Guanajuato, Mexico), Curt Struck (Iowa State University), Magnus Thomasson (Onsala Space Obs., Sweden), Maria Sundin (Goteborg University, Sweden), and Mario Klaric (Columbia, South Carolina).
Credits
NASA and The Hubble Heritage Team (STScI)| About The Object | |
|---|---|
| Object Name | NGC 2207, and IC 2163 |
| Object Description | Merging Galaxies |
| R.A. Position | 06h 16m 24.9s |
| Dec. Position | -21° 22' 26" |
| Constellation | Canis Major |
| Distance | 35 Mpc (114 million light-years) |
| Dimensions | The image is 2.5 arcminutes on the vertical side. NGC 2207 has a diameter of 143,000 light-years (44 kpc or 4'). IC 2163 has a diameter of 101,000 light-years (31 kpc or 3'). |
| About The Data | |
| Data Description | Principal Astronomers: D.M. Elmegreen (Vassar College), B.G. Elmegreen (IBM Research Division), M. Kaufman (Ohio State University), E. Brinks (Universidad de Guanajuato, Mexico), C.Struck (Iowa State University), M. Thomasson (Onsala Space Observatory, Sweden), M. Sundin (Götenborg University, Sweden), M. Klaric (Columbia, SC) |
| Instrument | HST>WFPC2 |
| Exposure Dates | May 25, 1996; November 11, 1998, Exposure Time: 4.5 hours |
| Filters | F336W (U), F439W (B), F555W (V), and F814W (I) |
| 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. |
