Hubble image archive
Halo of Andromeda Galaxy Used to Measure Its Drift Across Space
This composite image shows a region in the halo in the neighboring Andromeda galaxy that astronomers used to precisely measure the galaxy's sideways motion on the sky. This has allowed them to predict a direct collision between Andromeda and the Milky Way about 4 billion years fr...
- Date
- Jan 1, 2012
- Mission
- Hubble Space Telescope
- Archive ID
- hubblesite-images-2012-20-3037-image
This composite image shows a region in the halo in the neighboring Andromeda galaxy that astronomers used to precisely measure the galaxy's sideways motion on the sky. This has allowed them to predict a direct collision between Andromeda and the Milky Way about 4 billion years from now.
The inset image on the left is from a 2002 Hubble Space Telescope deep exposure that captured the light from 300,000 stars in Andromeda's halo, a vast spherical cloud of stars surrounding the galaxy's bright disk. Embedded in the image are numerous background galaxies that are much father away than Andromeda.
Astronomers compared this region to pictures of the same area taken seven years later. They measured the tiny amount of sideways drift in the halo stars relative to the stationary background galaxy field. The same measurements were done for two other fields in the galaxy as well. This is similar to measuring the drift of a boat relative to a background shoreline.
Credits
NASA, ESA, R. van der Marel and T. Brown (STScI), and the Digitized Sky SurveyImage Details
| About The Object | |
|---|---|
| Object Name | M31, NGC 224, Andromeda Galaxy |
| Object Description | Starfield in M31 |
| R.A. Position | 00h 42m 44s |
| Dec. Position | +41° 16' 9" |
| Constellation | Andromeda |
| Distance | About 2.5 million light-years (770 kiloparsecs) |
| About The Data | |
| Data Description | The Hubble data were taken from the HST proposals and , PI: T. Brown (STScI); and , PI: R. van der Marel (STScI). The science team comprises: R. van der Marel, S.T. Sohn, J. Anderson, and T. Brown (STScI), M. Fardal (University of Massachusetts, Amherst), G. Besla (Columbia University), R. Beaton (University of Virginia), P. Guhathakurta (UCO/Lick Observatory/UCSC), and T.J. Cox (Carnegie Observatories). |
| Instrument | HST>ACS/WFC and HST>WFC3/UVIS |
| Exposure Dates | December 2002 and January 2005; January 2010 and August 2010 |
| Filters | ACS/WFC: F606W (V) and F814W (I) WFC3/UVIS: F606W (V) |
| About The Image | |
| Color Info | This image is a composite of separate exposures acquired by the ACS instrument on HST. Several filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Blue: F606W (V) Red: F814W (I) |
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