![[Arp 102]](/image_gallery/images/d4/a102b.jpg)
Interacting galaxy system Arp 102
Downloadable versions (see
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About this object
Location: 17 18 00 +49 04 (1950.0), constellation of Hercules (just!).
Minimum credit line: C.F.Claver, N.A.Sharp (NOAO)/WIYN/NOAO/NSF
(for details see Conditions of Use)
834 x 400 14 kb color JPEG
3960 x 1900 360 kb color JPEG
3960 x 1900 7.3 Mb 8-bit color TIFF
3960 x 1900 22.0 Mb 24-bit color TIFF
About this image
This is a combination of several exposures taken
on the night of June 22nd 1995 (UT of observation 23/06/95:06:18 to
09:34) with a CCD detector on loan from Morley Block and the
manufacturer, Scientific Imaging Technologies (SITe), Inc.
This was one of the first of their new 2048x4096, 15 micron, three
side buttable, thinned, back-illuminated devices, quickly inserted
into a Kitt Peak standard dewar and installed on the WIYN 3.5m telescope.
Three exposures were taken through each of three different filters
approximating red (five minutes each), blue (fifteen minutes each), and
green (ten minutes each). The result is therefore a combination of an
hour and a half of observations.
The individual colors were aligned and combined in the computer
to create this (approximately) true color picture.
The pixel size on the sky is 0.139 arc seconds; after combination,
the final size is 1900x3960, or about 4.4x9.2 arc minutes.
The image quality was changing during the exposure sequence, and to make
the final picture the "seeing" measurement (average full-width half-maximum
(FWHM) for several stars) had to be matched across
all nine of the original frames, for a final value of about 1.0 arc seconds,
although the best single frame measured at 0.7 arc seconds.
Orientation: N to the right, E up.
This interesting interacting spiral/elliptical pair of galaxies was first
described in the Catalogue of Peculiar Galaxies, compiled by Halton Arp in 1966.
It is also pair number 508 in Igor Karachentsev's catalog of binary galaxies.
The large spiral galaxy (type SABb pec) shows long blue tidal tails caused by
its interaction with the southerly elliptical. In fact, this
"elliptical" is much the more interesting galaxy, despite its more
nondescript appearance. It is a broad line radio galaxy with an
unresolved core and a sub-parsec VLBI component at 6cm. It is also an
intermediate type Seyfert, meaning it has an active nucleus,
and it shows a double-peaked emission line profile (separation about
5000 km/s), which is considered to be strong evidence for the presence of an
accretion disk, probably around a central supermassive black hole.
In this picture we also see the presence of numerous more distant
background galaxies, showing as clusters of small, diffuse red objects
and scattered diffuse blue objects. These objects are very difficult to
detect and require excellent conditions and superb optics.
Distance: approximately 320 million light-years.
Return to:
galaxies page,
spiral galaxies page,
elliptical galaxies page,
WIYN galaxies page,
WIYN spiral galaxies page,
WIYN elliptical galaxies page.
Comments by e-mail to images@noao.edu
