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Notes for object NGC 6860

8 note(s) found in NED.


1. 2008ApJ...674..686W
Re:NGC 6860
NGC 6860.-As mentioned in {section} 3, the spectrum of NGC 6860 is quite
complex. Due to this complexity and a lack of signal-to-noise ratio (especially
considering that the pn data were corrupted), we are unsure of the true nature
of this spectrum. Therefore, we decided to compare the XMM and XRT spectra with
the pcfabs*pow model. This may not be the most valid description of the data,
but it gives a basis to compare the spectra. Using this model, we fit both of
the MOS observations (with the parameters n_H_ and {GAMMA} tied together while
the flux was allowed to vary) simultaneously with the XRT observation.
Variations were statistically significant for flux, n_H_, and {GAMMA} with
{DELTA}{chi}^2^ = 83, 56 and 15, respectively. The best fit for the partial
covering, pegged power-law model yielded {chi}^2^/dof of 513.3/430. Errors on
the column density were (3.33-6.09) x 10^22^ cm^-2^ (XMM) and (0.59-1.73) x
10^22^ cm^-2^ (XRT) with covering fraction errors of 0.0-0.66 (XMM) and
0.73-0.92 (XRT). The photon index errors were 0.64-0.88 (XMM) and 1.16-1.71
(XRT). Finally, errors on the flux from the pegged power-law component were
(1.06-1.19) x 10^-11^ ergs s^-1^ cm^-2^ (XMM MOS-1), (0.99-1.12) x 10^-11^ ergs
s^-1^ cm^-2^ (XMM MOS-2), and (1.44-1.88) x 10^-11^ ergs s^-1^ cm^-2^ (XRT).
These observations were taken 4 months apart. Interestingly, the XRT observation
is well fitted by the partial covering model, giving photon index and covering
fractions similar to the typical values seen in Table 8. However, the column
density is much lower (by a factor of 10 from the other sources). Between the
XRT and XMM observations, the column density seems to have doubled while the
photon index flattened and the flux decreased by nearly half.

2. 2006A&A...459...55B
Re:NGC 6860
A.2 NGC 6860
.
The luminous infrared galaxy NGC 6860 shows a composite nature of a Seyfert-1
nucleus embedded in a dusty star formation environment (Lipari et al. 1993).
While NED classify NGC 6860 as Seyfert 1, Cid Fernandes et al. (1998) and
Lipari et al. (1993) find emission lines typical of a Seyfert 1.5. Since the
narrow components in both H{alpha} and H{beta} which are superimposed on the
broad components are clearly visible in our central spectra, we agree with
Lipari et al. (1993) to classify NGC 6860 as Sy1.5.
.
Lipari et al. (1993) studied NGC 6860 in detail, presenting optical imaging,
as well as optical and near-infrared spectroscopy. The H{alpha}+[N II] image
shows a bright emission-line region associated with the AGN activity and a
circumnuclear ring of star formation with clear signs of young stars in the
spectrum. The [O III] image reveals emission extended by 10" in east-west
direction, perpendicular to the direction of the bar (PA_bar_ ~ 13^deg^).
Lipari et al. (1993) use templates from Bica (1988) to fit the stellar
population, finding that an S3 template represents the nuclear stellar
population, while the rather young population of an S6 template fits the inner
star formation ring. The bar reveals a typical spectrum of an old stellar
population. A high electron temperature (T_e,obs_ ~ 35 000 K) is observed
in the nuclear region. NGC 6860 is classified as a typical intermediate case
between AGN activity completely dominating the energy input and starburst
galaxy where the ionising continuum is spread over a much larger star-forming
region (Lipari et al. 1993). This is strengthened by line ratios in diagnostic
diagrams which locate the galaxy in a transitional zone between areas occupied
by AGNs and H II regions.
.
Besides MCG -05-13-017, NGC 6860 is the other galaxy in our sample which shows,
in all three diagnostic diagrams, a clear transition between central line ratios
falling in the AGN regime and outer ones typical of H II regions (Fig. 4). While
we detect [O III] emission at a S/N > 3 out to a distance of r ~ 10" in
east-west direction, comparable to the maximum extension of the [O III]
ground-based image of Lipari et al. (1993), the emission beyond 5" can be
attributed to circumnuclear star forming regions (Table 7). Our results confirm
the classification of NGC 6860 as an intermediate case between AGN activity and
starburst galaxy (Lipari et al. 1993). While Lipari et al. (1993) find line
ratios in the transitional zone between Seyfert galaxies and H II regions, we
are able to trace the radial varying ratios and determine the radius where the
transition takes place in all three diagnostic diagrams. Showing that the
transition occurs at the same distance in the second diagnostic diagram is
essential to exclude spatial variations in physical parameters resulting in a
transition of line ratios from the AGN to the H II-region regime despite an
intrinsic AGN photoionising source (Paper I). Thus, we can determine the NLR
size of NGC 6860 to a radius of r ~ 5" (observed along a PA of 85^deg^, i.e.
the AGN radiation field dominates over the stellar one in the inner 10". The
maximum [O III] extent we observe is four times larger than what is observed
in the HST [O III] image by Schmitt et al. (2003a) (d ~ 20" versus d ~ 5").
.
In the centre, we find a high electron temperature of T_e,obs_~36325 +/- 250K,
in agreement with the results of Lipari et al. (1993) (Table 4). The reddening
values vary rather randomly. Moreover, there is no significant difference
between the reddening in the NLR and that in the surrounding H II regions
(Fig. 3). The BLR shows a reddening comparable to that of the NLR (in the
central 2": H{alpha}_broad_/H{beta}_broad_ ~ 5.5, E_B-V_ ~ 0.6 mag). As in
Fairall 51, it indicates dust in the host galaxy.

3. 2004MNRAS.353.1151S
Re:NGC 6860
NGC 6860. Has been studied as part of the H_2_0 megamaser sample of
galaxies observed by Braatz et al. (1996).

4. 2004A&A...415..941E
Re:NGC 6860
NGC 6860: Suggested as double-barred by Marquez et al. (1999), based on features
in their near-IR ellipse fits and color maps. Because the ellipse-fit features
(a < 2") are only slightly larger than their seeing (FWHM ~ 0.9"), this is
unfortunately not a clear detection; higher-resolution images are clearly
needed. (The available HST images are off-center or too low in signal to be
useful.)

5. 2003ApJS..148..327S
Re:NGC 6860
5.52. NGC 6860
Ground-based narrowband images of this Seyfert 1 galaxy, published by
Lipari, Tsvetanov, & Macchetto (1993), show emission extended by 10"
along the E-W direction. Our [O III] image (Fig. 13, middle right)
shows emission along the same direction, consisting of an S-shaped
NLR along P.A. = 85^deg^, extended by ~4.5" in this direction (1300
pc) and 2.4" (690 pc) in the perpendicular direction. Most of the
emission is concentrated at the nucleus and in a blob 0.4" east, with
a second more extended and fainter structure at 0.9" east. To the
west of the nucleus we see a long arm of emission extending by ~0.8"
and a more diffuse structure at 2.5".

6. 1999A&AS..140....1M
Re:NGC 6860
This galaxy has an asymmetrical bar along PA ~ 10^deg^, more extended to
the north than to the south (Fig. 16a). The ring is not apparent in the
K' image, where we barely detect the beginning of a spiral arm north of
the bar.
The bar in the sharp-divided image appears clearly bent (Fig. 16b),
possibly due to the dynamical effects of a small inner bar (Figs. 16b,
16c, 16d). The difference image (Fig. 16c) also evidences a faint spiral
arm detaching from the southern end of the outer bar to the north east,
and a brighter, tighter arm starting at the west end of the inner bar to
the South. The variations of {epsilon} and PA with radius (Fig. 16e)
hints on the presence of a secondary bar.
The J/K' image confirms the existence of a small redder inner bar
(Fig. 16d), that is also evidenced by the dust lane structure in the
HST image by Malkan et al. (1998). The main bar and the beginning of the
spiral arms appear as bumps in the bulge + disk fit (Figs. 16f and 16g).
The color gradient is very steep in the central regions (Fig. 16h).

7. 1998MNRAS.297..579C
Re:NGC 6860
NGC 6860. According to Lipari, Tsvetanov & Macchetto (1993) the H{alpha} image
of this galaxy shows bright emission-line regions associated with the nucleus
and a circumnuclear ring of star formation. The emission-line spectrum is
typical of a Seyfert 1.5 and variable. The Ws (Fig. 9) are diluted by an FC at
the nucleus. Their values change to those of an S2 template at 4 arcsec and
farther out. The continuum ratios show a gradient in the opposite direction,
decreasing from S4 in the inner 5 arcsec radius to S5 farther out, bluer than
the values indicated by the Ws in the outer regions.

8. 1985SGC...C...0000C
Re:NGC 6860
Plate 917
Overexposed center. Extremely faint outer arms. 3 stars north. Low surface
brightness SB(s)m IV-V 3.4 north-following.


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