It came from outer space

Esahubble_potw1406a_1024

esahubble_potw1406a February 10th, 2014

Credit: NASA, ESA, and A. Sarajedini (University of Florida) Acknowledgement: Gilles Chapdelaine

Named after its discoverer, the French-Armenian astronomer Agop Terzan, this is the globular cluster Terzan 7 a densely packed ball of stars bound together by gravity. It lies just over 75 000 light-years away from us on the other side of our galaxy, the Milky Way. It is a peculiar cluster, quite unlike others we observe, making it an intriguing object of study for astronomers. Evidence shows that Terzan 7 used to belong to a small galaxy called the Sagittarius Dwarf Galaxy, a mini-galaxy discovered in 1994. This galaxy is currently colliding with, and being absorbed by, the Milky Way, which is a monster in size when compared to this tiny one. It seems that this cluster has already been kidnapped from its former home and now is part of our own galaxy. Astronomers recently discovered that all the stars in Terzan 7 were born at around the same time, and are about eight billion years old. This is unusually young for such a cluster. The shared birthday is another uncommon property; a large number of globular clusters, both in the Milky Way and in other galaxies, seem to have at least two clearly differentiated generations of stars that were born at different times. Some explanations suggest that there is something different about clusters that form within dwarf galaxies, giving them a different composition. Others suggest that clusters like Terzan 7 only have enough material to form one batch of stars, or that perhaps its youthfulness has prevented it from yet forming another generation. A version of this image was entered into the Hubble's Hidden Treasures image processing competition by contestant Gilles Chapdelaine.

Provider: Hubble Space Telescope | ESA

Image Source: https://www.spacetelescope.org/images/potw1406a/

Curator: ESA/Hubble, Garching bei München, Germany

Image Use Policy: Creative Commons Attribution 4.0 International License

Image Details

Image Type
Observation
Object Name
Sagittarius Dwarf Galaxy Terzan 7
Subject - Milky Way
Star > Grouping > Cluster > Globular
Esahubble_potw1406a_128
 

Position Details

Position (ICRS)
RA = 19h 17m 43.8s
DEC = -34° 39’ 25.4”
Orientation
North is 9.7° CW
Field of View
3.6 x 3.5 arcminutes
Constellation
Sagittarius

Color Mapping

  Telescope Spectral Band Wavelength
Cyan Hubble (ACS) Optical (V) 606.0 nm
Orange Hubble (ACS) Infrared (I) 814.0 nm
Spectrum_base
Cyan
Orange
Esahubble_potw1406a_1280
×
ID
potw1406a
Subject Category
B.3.6.4.2  
Subject Name
Sagittarius Dwarf Galaxy, Terzan 7
Credits
NASA, ESA, and A. Sarajedini (University of Florida) Acknowledgement: Gilles Chapdelaine
Release Date
2014-02-10T10:00:00
Lightyears
Redshift
Reference Url
https://www.spacetelescope.org/images/potw1406a/
Type
Observation
Image Quality
Distance Notes
Facility
Hubble Space Telescope, Hubble Space Telescope
Instrument
ACS, ACS
Color Assignment
Cyan, Orange
Band
Optical, Infrared
Bandpass
V, I
Central Wavelength
606, 814
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
ICRS
Equinox
J2000
Reference Value
289.432365277, -34.6570650643
Reference Dimension
4295.0, 4169.0
Reference Pixel
2147.0, 2084.0
Scale
-1.39105243979e-05, 1.39105243979e-05
Rotation
-9.74
Coordinate System Projection:
TAN
Quality
Full
FITS Header
Notes
Creator (Curator)
ESA/Hubble
URL
http://www.spacetelescope.org/
Name
Email
Telephone
Address
Karl-Schwarzschild-Strasse 2
City
Garching bei München
State/Province
Postal Code
D-85748
Country
Germany
Rights
Creative Commons Attribution 4.0 International License
Publisher
ESA/Hubble
Publisher ID
esahubble
Resource ID
potw1406a
Metadata Date
2013-08-30T18:56:54+02:00
Metadata Version
1.1
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Detailed color mapping information coming soon...

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There is no distance meta data in this image.

 

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