Sasmirala Individual Information for NGC 6890

Description

NGC 6890 is a low-inclination grand-design spiral galaxy at a redshift of z = 0.0081(D ~ 33.8 Mpc) with a Sy 1.9/2 nucleus [phillips_nearby_1983, storchi-bergmann_stellar_1990]. The nucleus is detected but unresolved at arcsecond resolution at radio wavelengths [ulvestad_radio_1989, morganti_radio_1999]. After its detection with IRAS, NGC 6890 was followed up in the MIR with Spitzer/IRAC, IRS and MIPS. The corresponding IRAC and MIPS images show a dominant compact nucleus embedded within faint spiral-like host emission. Our nuclear IRAC 5.8 and 8.0μm photometry is significantly lower than the values published by [gallimore_infrared_2010] but agree with the Spitzer/IRS mapping-mode post-BCD spectrum. The latter suffers from low S/N but indicates weak silicate 10 and 18 μm emission, weak PAH features, and a red spectral slope in νFν-space (see also [buchanan_spitzer_2006, tommasin_spitzer_2008, tommasin_spitzer-irs_2010, wu_spitzer/irs_2009, gallimore_infrared_2010]). Thus, the arcsecond-scale MIR SED indicates unobscured AGN emission with minor star-formation contribution. The nuclear region of NGC 6890 was observed with T-ReCS in the broad N filter in 2004 [videla_nuclear_2013] and an apparently elongated nucleus without further host emission was detected (FWHM(major axis)~ 0.42arcsec ~ 68 pc; PA~ 102). However, at least a second epoch of MIR subarcsecond imaging is required to confirm this elongation. Our nuclear photometry is consistent with the value published by [videla_nuclear_2013] and also marginally consistent with the Spitzer spectrophotometry (~ 18% lower). Therefore, we use the latter to compute the nuclear 12 μm continuum emission estimate.

Images

Optical image (DSS, red filter). Displayed are the central 4 arcmin with North being up and East to the left. The colour scaling is linear with white corresponding to the median background (BG) and black to the 0.01% pixels with the highest intensity.

Spitzer MIR images. Displayed are the inner 40 arcsec with North being up and East to the left. The colour scaling is logarithmic with white corresponding to median BG and black to the 0.1% pixels with the highest intensity. The label in the bottom left states instrument and central wavelength of the filter in micron (I: IRAC, M: MIPS).

Subarcsecond-resolution MIR images sorted by increasing filter central wavelength. Displayed are the inner 4 arcsec with North being up and East to the left. The colour scaling is logarithmic with white corresponding to median BG and black to the 75% of the highest intensity of all images in units of sig_bg. The inset image (where present; either bottom or top right) shows the central arcsecond of the PSF from the calibrator star, scaled to match the science target. The labels in the bottom left state instrument and filter names (C: COMICS, M: Michelle, T: T-ReCS, V: VISIR).

SEDs

MIR SED. The description of the symbols in all the SED plots (where present) is the following: Grey crosses and solid lines mark the Spitzer/IRAC, MIPS and IRS data. The colour coding of the other symbols is as follows: green for COMICS, magenta for Michelle, blue for T-ReCS and red for VISIR data. Darker-coloured solid lines mark spectra of the corresponding instrument. The black filled circles mark the nuclear 12 and 18 micron continuum emission estimate from the data (where present). The ticks on the top axis mark positions of common MIR emission lines, while the light grey horizontal bars mark wavelength ranges affected by the silicate 10 and 18 micron features.

Photometry details and reduced FITS files

ObjectRA
[deg]
Dec
[deg]
FilterImageInfoλ_c
[um]
HWHM
[um]
InstrPix. size
[arcsec/pix]
T_exp
[s]
ModeChop Throw
[arcsec]
Chop Angle
[deg]
Rot
[deg]
Prog IdCal. StarCal. DateDate Obs.Factor
[mJy/ct]
Err. Factor
[mJy/ct]
Cal. Flux
[mJy]
Upper Lim. Gauss?F_Gauss
[mJy]
E(F_Gauss)
[mJy]
Upper Lim. PSF?F_PSF
[mJy]
E(F_PSF)
[mJy]
Cal. Maj.
[arcsec]
Cal. Min.
[arcsec]
Cal. PA.
[deg]
Maj. Ax
[arcsec]
Min. Ax
[arcsec]
Pos. Ang.
[deg]
NGC 6890304.575417-44.806667NNGC6890_N_2004-07-08T07-24.fits[Details]10.362.64TRECS0.09717.0PARA15.0-90.00.0GS-2004A-Q-14HD1783452004-07-08T05:31:12Z2004-07-08T07:24:58Z0.006546e-0510810.0False93.01.7False74.81.70.350.35112.00.420.36102.0