Meeting the neighbours

Esahubble_potw1523a_500

esahubble_potw1523a June 8th, 2015

Credit: ESA/Hubble & NASA

There are many galaxies in the Universe and although there is plenty of room, they tend to stick together. The Milky Way, for example, is part of a large gathering of over fifty galaxies known as the Local Group. Galaxy groups like this come together to form even larger groups called clusters which can congregate further still to create mammoth superclusters. The sphere of space surrounding our galaxy is known as the Local Volume, a region some 35 million light-years in diameter and home to several hundred known galaxies. The subject of this new NASA/ESA Hubble Space Telescope image, a beautiful dwarf irregular galaxy known as PGC 18431, is one of these galaxies. This image shows PGC 18431 smudged across the sky, but it wasnt imaged purely for its looks. These Hubble observations were gathered in order to probe how Local Volume galaxies cluster together and move around. Hubbles high resolution allows astronomers to explore star populations within these moderately distant galaxies specifically, stars known as tip of the red-giant branch stars in order to get an idea of the galaxys composition and, crucially, its distance from us. Knowing galactic distances enables us to accurately map a galaxy sample in three dimensions, a method key to understanding more about our cosmic neighbours, and to dismiss perspective and line-of-sight illusions.

Image Source: http://www.spacetelescope.org/images/potw1523a/

Curator: ESA/Hubble, Garching bei München, Germany

Image Use Policy: Creative Commons Attribution 3.0 Unported license

Image Details

Image Type
Observation
Object Name
PGC 18431
Subject - Local Universe
Galaxy » Type » Irregular
Esahubble_potw1523a_128
 

Position Details

Position (ICRS)
RA = 6h 7m 19.2s
DEC = -34° 12’ 8.8”
Orientation
North is 104.3° CW
Field of View
3.2 x 1.6 arcminutes
Constellation
Columba

Color Mapping

  Telescope Spectral Band Wavelength
Arrow_left_cyan Hubble Space Telescope (ACS) Optical (V) 606.0 nm
Arrow_left_orange Hubble Space Telescope (ACS) Infrared (I) 814.0 nm
Spectrum_base
Arrow_top_cyan
Arrow_top_orange
Esahubble_potw1523a_1280
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ID
potw1523a
Subject Category
C.5.1.6  
Subject Name
PGC 18431
Credits
ESA/Hubble & NASA
Lightyears
Redshift
Reference Url
http://www.spacetelescope.org/images/potw1523a/
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
91.8301750629, -34.2024382472
Reference Dimension
3870.0, 1931.0
Reference Pixel
1935.0, 965.0
Scale
-1.38934937937e-05, 1.38934937937e-05
Rotation
-104.33999999999999
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 3.0 Unported license
Publisher
ESA/Hubble
Publisher ID
esahubble
Resource ID
potw1523a
Metadata Date
2014-11-28T19:04:02+01:00
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.