Messier 71: an unusual globular cluster

Esahubble_potw1018a_1024

esahubble_potw1018a August 23rd, 2010

Credit: ESA/Hubble and NASA

This spectacular NASA/ESA Hubble Space Telescope image shows a bright scattering of stars in the small constellation of Sagitta (the Arrow). This is the centre of the globular cluster Messier 71, a great ball of ancient stars on the edge of our galaxy around 13 000 light-years from Earth. M71 is around 27 light-years across. Globular clusters are like galactic suburbs, pockets of stars that exist on the edge of major galaxies. These clusters are tightly bound together by their gravitational attraction, hence their spherical shape and their name: globulus means little sphere in Latin. Around 150 such globular clusters are known to exist around our Milky Way, each one of them containing several hundred thousand stars. Messier 71 has been known for a long time, having been first spotted in the mid eighteenth century by Swiss astronomer Jean-Philippe de Cheseaux. Cheseaux discovered a number of nebulae in his career, and also spent much time studying religion: one posthumously published work attempted to derive the exact date of Christs crucifixion from astronomical events noted in the Bible. Despite being a familiar object, Messier 71s precise nature was disputed until recently. Was it simply an open cluster, a loosely bound group of stars? This was for many years the dominant view. But in the 1970s, astronomers came to the view that it is in fact a relatively sparse globular cluster. The stars in Messier 71, as is usual in such clusters, are relatively old, at around 9 to 10 billion years, and consequently are low in elements other than hydrogen and helium. This picture was created from images taken with the Wide Field Channel of the Advanced Camera for Surveys on Hubble. It is a combination of images taken through yellow (F606W coloured blue) and near-infrared (F814W coloured red) filters. The exposure times were 304 s and 324 s respectively. The field of view is about 3.4 arcminutes across.

Provider: Hubble Space Telescope | ESA

Image Source: http://www.spacetelescope.org/images/potw1018a/

Curator: ESA/Hubble, Garching bei München, Germany

Image Use Policy: Creative Commons Attribution 4.0 International License

Image Details

Image Type
Observation
Object Name
Messier 71
Subject - Milky Way
Star > Grouping > Cluster > Globular
Esahubble_potw1018a_128
 

Position Details

Position (ICRS)
RA = 19h 53m 45.9s
DEC = 18° 46’ 45.7”
Orientation
North is 114.5° CCW
Field of View
3.4 x 3.4 arcminutes
Constellation
Sagitta

Color Mapping

  Telescope Spectral Band Wavelength
Blue Hubble (ACS) Optical (V) -
Green Hubble (ACS) Optical (Pseudogreen (V+I)) -
Red Hubble (ACS) Infrared (I) -
Esahubble_potw1018a_1280
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ID
potw1018a
Subject Category
B.3.6.4.2  
Subject Name
Messier 71
Credits
ESA/Hubble and NASA
Release Date
2010-08-23T10:00:00
Lightyears
Redshift
Reference Url
http://www.spacetelescope.org/images/potw1018a/
Type
Observation
Image Quality
Distance Notes
Facility
Hubble Space Telescope, Hubble Space Telescope, Hubble Space Telescope
Instrument
ACS, ACS, ACS
Color Assignment
Blue, Green, Red
Band
Optical, Optical, Infrared
Bandpass
V, Pseudogreen (V+I), I
Central Wavelength
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
ICRS
Equinox
J2000
Reference Value
298.441141757, 18.7793655767
Reference Dimension
4033.0, 4073.0
Reference Pixel
2016.5, 2036.5
Scale
-1.38842411509e-05, 1.38842411509e-05
Rotation
114.49999999999993
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
potw1018a
Metadata Date
2010-07-28T14:15:21+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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