Compass and Scale Image for HCG 31
Hickson Compact Group 31, HCG 31
166 million light-years (51 million parsecs)
This image is 3.2 arcminutes (156,000 light-years or 48,000 parsecs) wide.
This image was created from HST data from proposal 10787: J. Charlton (Pennsylvania State University), A. Zabludoff (University of Arizona), M. de Oliveira (University of São Paulo, Brazil), J. Hibbard (AURA/NRAO), S. Zonak (University of Maryland), A. Hornschemeier (NASA/GSFC), P. Hickson (University of British Columbia), J. Mulchaey (Carnegie Institution of Washington), K. Johnson (University of Virginia), A. Maybhate (STScI), R. Chandar (University of Toledo), S. Gallagher (The University of Western Ontario), C. Palma, S. Hunsberger, N. Brandt, and M. Eracleous (Pennsylvania State University), P. Durrell (Youngstown State University), J. English (University of Manitoba), B. Whitmore (STScI), D. Elmegreen (Vassar College), and K. Knierman (Arizona State University).
The science team comprises: S. Gallagher (The University of Western Ontario), P. Durrell (Youngstown State University), D. Elmegreen (Vassar College), R. Chandar (University of Toledo), J. English (University of Manitoba), J. Charlton, C. Gronwall, and J. Young (Pennsylvania State University), P. Tzanavaris (NASA/GSFC), K. Johnson (University of Virginia/NRAO), M. de Oliveira (University of São Paulo, Brazil), B. Whitmore (STScI), A. Hornschemeier (NASA/GSFC), et al.
HST>ACS: F435W (B), F606W (V), and F814W (I)
HST>WFPC2: F439W (B), F555W (V), F675W (R), and F814W (I)
Spitzer>IRAC: 8 micron
GALEX: NUV Imaging Channel
Note: Spitzer and GALEX data were combined with the Hubble data to create the composite image. The Spitzer data were taken February 22, 2005 (PI: K. Johnson, University of Virginia/NRAO). The GALEX data were taken December 27, 2004 (archival data). A small amount of WFPC2 data (proposal 5900, PI: P. Conti) taken on October 7, 1995, was used to fill in a portion of the ACS/WFC chip gap in this composite image of HCG 31.
This image is a composite of separate exposures acquired by three separate space telescopes. Exposures in the optical range of the spectrum were acquired with ACS and WFPC2 instruments on the Hubble Space Telescope (HST). The near-ultraviolet light was acquired by the Galaxy Evolution Explorer (GALEX), while near-infrared emission was captured by the IRAC instrument on the Spitzer Space Telescope (SST). Several filters were used to sample these wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are:
Red: ACS F814W (I) + WFPC2 F814W (I)
Yellow/green: ACS F606W (V) + WFPC2 F555W (V) + WFPC2 F675W (R)
Blue: ACS F435W (B) + WFPC2 F439W (B)
Orange: IRAC 8 micron
Purple: GALEX NUV Imaging Channel