The target of this field was the almost edge-on spiral galaxy NGC 4666 which
dominates the center of the field. Although the target was optically and X-ray
extended, the target was included in the public survey since the target blocks
only about 5% of the field of view. The X-ray image is a combined image of the
three EPIC cameras of the single observation of the target, all taken in full
NGC 4666.---SBc?: System close to edge-on. Bright nucleus embedded in
a thin HSB bar. Bulge is small and flattened. There appears to be
spiral structure emanating from the ends of the bar, but the system
inclination makes the spiral pattern hard to see. Any spiral pattern is
flocculent, rather than grand design. The ends of the bar and the
disk are full of star-forming knots and patches of extinction.
The HRI image of NGC 4666 shows faint diffuse emission that extends
along the major axis and is confined mostly to the disk plane. It is
possible that further diffuse emission extends perpendicular to the disk
to the southeast but is absorbed by the intervening H I disk (see D97).
There are also two pointlike sources located ~1' along the minor axis
above and below the nuclear region. These might contribute significantly
to the apparently extended emission structure visible in our 1.5 keV
PSPC image (Fig. 22; section 3.3) and possibly also in the 0.75 keV map
(Fig. 23). However, owing to the extended nature and the very low
surface brightness of the emission picked up by the PSPC at 0.25 keV
(Fig. 24), it is very unlikely that any of this emission could come from
either of the two point sources. The response of the HRI picks up harder
emission than 0.25 keV, and its sensitivity to low surface brightness soft
emission is more than 10 times lower than that of the PSPC.
This galaxy shows predominantly hard (1.5 and also 0.75 keV) emission,
mostly from its disk plane. The emission is extended (about 3.6', i.e.,
28 kpc) along the major axis. Along the minor axis of NGC 4666, above
and below the nuclear region, two extensions can be seen in both the
0.75 and 1.5 keV bands. The off-axis emission in the 1.5 keV band is
probably at least partly caused by chance superpositions with nearby
point sources (see Fig. 6). However, in the 0.75 keV map, little if any
emission is visible that arises from the locations of these two sources.
And at 0.25 keV, there is no visible correspondence with the HRI
emission distribution at all. The single-sidedness of emission at
0.25 keV only northwest of the galaxy disk suggests that diffuse soft
emission from the southeast side is obscured by the intervening H I disk
After excision of the high surface brightness emission visible in
Figures 22 and 23 and subsequent smoothing of the data, no underlying
more diffuse emission could be detected beyond what is already visible
in the original images. This is probably a limitation of the angular
resolution of the data. Therefore, the raw images are also the final
ones that are overlaid on the DSS image.
In the case of NGC 4666, the halo could not be spatially separated from
the disk emission in the PSPC data and so an integral spectrum was
extracted (SECTION 3.4.3).
March 23/24, 1980
NGC 4666 is in the busy area of the
southern extension of the Virgo Cluster, at RA =
12^h^ 42^m^, Dec = -00^deg^ 11'. It forms an apparent
pair with NGC 4668 (SBc; panel 313), at a
separation of 7.8'. The redshifts are v_o(4668) =
1530 km/s and v_o(4666) = 1474 km/s. NGC 4632
(Sc; panel 288), with a redshift of v_o = 1557 km/s,
is 46' distant from NGC 4666. At a
mean redshift distance of 30 Mpc for the
apparent triplet, the projected linear separations
of NGC 4668 and NGC 4632 from NGC 4666
are 68 kpc and 400 kpc, respectively.
= Holm 453a.
Non-interacting pair with NGC 4668 at 7.3 arcmin
Observatory, 88, 239, 1968.
Rotation Curve and Systemic Velocity
Astr. Ap., 8, 364, 1970.
IAU Circ. No. 1908, 1965.
Ast. Tsirk., No. 331, 1965.
Sov. A. J., 10, 728, 1966.
Austral. J. Phys., 21, 193, 1968.
Astr. Ap., 31, 447, 1974.
SABc: (de Vaucouleurs), Sc- (Holmberg)
Paired with UGC 07931 at 7.3, 127
See UGC 07900
= Holm 453a
Bright nuclear region. Many knotty, branching arms with dark lanes.
Lund 9 dimensions are for the bright part only.
Non-interacting pair with NGC 4668 at 7.3 arcmin.
M.N.R.A.S., 94, 806, 1934.
Bright spiral 4' x 0.6' in p.a. 45^deg^. Nucleus bright and elongated; numerous
almost stellar condensations. Well marked absorption effect on southeast side.
See Abs. Eff. 8 s.n.