Rings Around the Galaxy

Spitzer_sig07-008a_1024

spitzer_sig07-008a May 30th, 2007

Credit: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

Three newly-discovered streams arcing high over the Milky Way Galaxy are remnants of cannibalized galaxies and star clusters. The streams are between 13,000 and 130,000 light-years distant from Earth and extend over much of the Northern sky.

Two of the newly discovered streams are almost certainly the remains of ancient star clusters. Known to astronomers as globular clusters, these giant stellar cities contain between tens of thousands and millions of stars. Though only about 150 globular clusters orbit the Milky Way today, they may once have numbered in the thousands.

Over billions of years, the relentless gravitational stresses inflicted on them by our galaxy have slowly torn them apart, leaving behind long, thin streams of stars. Once crowded so closely together that they could sometimes actually collide, these stars are now separated by many light-years, trailing one another at half a million miles an hour through the dark and lonely reaches of the galactic halo.

The third stream is spread over a much larger region of the sky, and is most likely the scattered remains of a dwarf galaxy. Such dwarf galaxies may contain up to 100 million stars, along with sometimes substantial amounts of mysterious "dark matter." While the Milky Way galaxy currently hosts a family of 20 or so known dwarf galaxies, scientists who study the growth of galaxies in the early universe have long been puzzled as to why we don't see hundreds of them.

Provider: Spitzer Space Telescope

Image Source: http://www.spitzer.caltech.edu/images/2136-sig07-008a-Rings-Around-the-Galaxy

Curator: Spitzer Space Telescope, Pasadena, CA, USA

Image Use Policy: Public Domain

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Image Details

Image Type
Artwork
Object Name
Milky Way
Subject - Milky Way
Galaxy > Type > Spiral
Galaxy > Type > Barred
Galaxy > Activity > Normal
Spitzer_sig07-008a_1280
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ID
sig07-008a
Subject Category
B.5.1.1.   B.5.1.2   B.5.3.1  
Subject Name
Milky Way
Credits
NASA/JPL-Caltech/R. Hurt (SSC/Caltech)
Release Date
2007-05-30
Lightyears
Redshift
Reference Url
http://www.spitzer.caltech.edu/images/2136-sig07-008a-Rings-Around-the-Galaxy
Type
Artwork
Image Quality
Good
Distance Notes
Facility
Instrument
Color Assignment
Band
Bandpass
Central Wavelength
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
Equinox
Reference Value
Reference Dimension
Reference Pixel
Scale
Rotation
Coordinate System Projection:
Quality
FITS Header
Notes
Creator (Curator)
Spitzer Space Telescope
URL
http://www.spitzer.caltech.edu
Name
Spitzer Space Telescope
Email
Telephone
Address
1200 E. California Blvd.
City
Pasadena
State/Province
CA
Postal Code
91125
Country
USA
Rights
Public Domain
Publisher
Spitzer Science Center
Publisher ID
spitzer
Resource ID
sig07-008a.tif
Metadata Date
2011-09-06
Metadata Version
1.1
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