A distinctly disorganised dwarf

Esahubble_potw1613a_1024

esahubble_potw1613a March 28th, 2016

Credit: ESA/Hubble & NASA Acknowledgement: Judy Schmidt (Geckzilla)

Despite being less famous than their elliptical and spiral galactic cousins, irregular dwarf galaxies, such as the one captured in this NASA/ESA Hubble Space Telescope image, are actually one of the most common types of galaxy in the Universe. Known as UGC 4459, this dwarf galaxy is located approximately 11 million light-years away in the constellation of Ursa Major (The Great Bear), a constellation that is also home to the Pinwheel Galaxy (M101), the Owl Nebula (M97), Messier 81, Messier 82 and several other galaxies all part of the M81 group. UGC 4459s diffused and disorganised appearance is characteristic of an irregular dwarf galaxy. Lacking a distinctive structure or shape, irregular dwarf galaxies are often chaotic in appearance, with neither a nuclear bulge a huge, tightly packed central group of stars nor any trace of spiral arms regions of stars extending from the centre of the galaxy. Astronomers suspect that some irregular dwarf galaxies were once spiral or elliptical galaxies, but were later deformed by the gravitational pull of nearby objects. Rich with young blue stars and older red stars, UGC 4459 has a stellar population of several billion. Though seemingly impressive, this is small when compared to the 200 to 400 billion stars in the Milky Way! Observations with Hubble have shown that because of their low masses, star formation is very low compared to larger galaxies. Only very little of their original gas has been turned into stars. Thus, these small galaxies are interesting to study to better understand primordial environments and the star formation process.

Provider: Hubble Space Telescope | ESA

Image Source: https://www.spacetelescope.org/images/potw1613a/

Curator: ESA/Hubble, Garching bei München, Germany

Image Use Policy: Creative Commons Attribution 4.0 International License

Image Details

Image Type
Observation
Object Name
UGC 4459
Subject - Local Universe
Galaxy > Size > Dwarf
Esahubble_potw1613a_128
 

Position Details

Position (ICRS)
RA = 8h 34m 6.9s
DEC = 66° 10’ 41.3”
Orientation
North is 32.2° CW
Field of View
2.8 x 2.0 arcminutes
Constellation
Ursa Major

Color Mapping

  Telescope Spectral Band Wavelength
Blue Hubble (WFC3) Ultraviolet (B) 438.0 nm
Blue Hubble (WFC3) Ultraviolet (U) 336.0 nm
Blue Hubble (WFC3) Ultraviolet (UV) 275.0 nm
Green Hubble (ACS) Optical (V) 555.0 nm
Red Hubble (ACS) Optical (A-alpha) 656.0 nm
Red Hubble (ACS) Infrared (I) 814.0 nm
Spectrum_base
Blue
Blue
Blue
Green
Red
Red
Esahubble_potw1613a_1280
×
ID
potw1613a
Subject Category
C.5.2.2  
Subject Name
UGC 4459
Credits
ESA/Hubble & NASA Acknowledgement: Judy Schmidt (Geckzilla)
Release Date
2016-03-28T06:00:00
Lightyears
Redshift
Reference Url
https://www.spacetelescope.org/images/potw1613a/
Type
Observation
Image Quality
Distance Notes
Facility
Hubble Space Telescope, Hubble Space Telescope, Hubble Space Telescope, Hubble Space Telescope, Hubble Space Telescope, Hubble Space Telescope
Instrument
WFC3, WFC3, WFC3, ACS, ACS, ACS
Color Assignment
Blue, Blue, Blue, Green, Red, Red
Band
Ultraviolet, Ultraviolet, Ultraviolet, Optical, Optical, Infrared
Bandpass
B, U, UV, V, A-alpha, I
Central Wavelength
438, 336, 275, 555, 656, 814
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
ICRS
Equinox
J2000
Reference Value
128.528675925, 66.1781475586
Reference Dimension
3306.0, 2392.0
Reference Pixel
1653.0, 1196.0
Scale
-1.38844570866e-05, 1.38844570866e-05
Rotation
-32.179999999999929
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
potw1613a
Metadata Date
2015-12-17T18:35:21+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.

 

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