Cosmic search for a missing limb

Esahubble_potw1746a_1024

esahubble_potw1746a November 13th, 2017

Credit: ESA/Hubble & NASA

This new Picture of the Week, taken by the NASA/ESA Hubble Space Telescope, shows the dwarf galaxy NGC 4625, located about 30 million light-years away in the constellation of Canes Venatici (The Hunting Dogs). The image, acquired with the Advanced Camera for Surveys (ACS), reveals the single spiral arm of the galaxy, which gives it an asymmetric appearance. But why is there only one spiral arm, when spiral galaxies normally have at least two? Astronomers looked at NGC 4625 in different wavelengths in the hope of solving this cosmic mystery. Observations in the ultraviolet provided the first hint: in ultraviolet light the disc of the galaxy appears four times larger than on the image depicted here. An indication that there are a large number of very young and hot hence mainly visible in the ultraviolet stars forming in the outer regions of the galaxy. These young stars are only around one billion years old, about 10 times younger than the stars seen in the optical centre. At first astronomers assumed that this high star formation rate was being triggered by the interaction with another, nearby dwarf galaxy called NGC 4618. They speculated that NGC 4618 may be the culprit harassing NGC 4625, causing it to lose all but one spiral arm. In 2004 astronomers found proof for this claim: The gas in the outermost regions of the dwarf galaxy NGC 4618 has been strongly affected by NGC 4625.

Provider: Hubble Space Telescope | ESA

Image Source: https://www.spacetelescope.org/images/potw1746a/

Curator: ESA/Hubble, Garching bei München, Germany

Image Use Policy: Creative Commons Attribution 4.0 International License

Image Details

Image Type
Observation
Object Name
NGC 4625
Subject - Local Universe
Galaxy > Type > Spiral
Galaxy > Component > Spiral Arm
Esahubble_potw1746a_128
 

Position Details

Position (ICRS)
RA = 12h 41m 52.8s
DEC = 41° 16’ 25.9”
Orientation
North is 22.5° CCW
Field of View
2.8 x 1.5 arcminutes
Constellation
Canes Venatici

Color Mapping

  Telescope Spectral Band Wavelength
Green Hubble (WFPC2) Optical (V) 555.0 nm
Red Hubble (WFPC2) Optical (NII) 658.0 nm
Blue Hubble (ACS) Optical (V) 606.0 nm
Green Hubble (ACS) Optical (V) 606.0 nm
Green Hubble (ACS) Optical (I) 814.0 nm
Red Hubble (ACS) Optical (I) 814.0 nm
Spectrum_base
Green
Red
Blue
Green
Green
Red
Esahubble_potw1746a_1280
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ID
potw1746a
Subject Category
C.5.1.1   C.5.4.7  
Subject Name
NGC 4625
Credits
ESA/Hubble & NASA
Release Date
2017-11-13T06:00:00
Lightyears
Redshift
Reference Url
https://www.spacetelescope.org/images/potw1746a/
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
WFPC2, WFPC2, ACS, ACS, ACS, ACS
Color Assignment
Green, Red, Blue, Green, Green, Red
Band
Optical, Optical, Optical, Optical, Optical, Optical
Bandpass
V, NII, V, V, I, I
Central Wavelength
555, 658, 606, 606, 814, 814
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
ICRS
Equinox
J2000
Reference Value
190.47011403, 41.2738599377
Reference Dimension
3386.0, 1806.0
Reference Pixel
1693.0, 903.0
Scale
-1.38812144685e-05, 1.38812144685e-05
Rotation
22.500000000000021
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
potw1746a
Metadata Date
2017-06-09T15:19:29+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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