Optical, Far-Infrared and X-ray Properties of the FIR quiescent Sc Galaxy NGC~247

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Session 48 -- Spiral, Dwarf and Irregular Galaxies
Display presentation, Wednesday, 1, 1994, 9:20-6:30

[48.08] Optical, Far-Infrared and X-ray Properties of the FIR quiescent Sc Galaxy NGC~247

G. Mackie, Y. Ikebe, G. Fabbiano, D.-W. Kim (SAO)

We present a multi-wavelength study of the large Sc galaxy, NGC~247 in the Sculptor group. Optical (B, I and H$\alpha$) CCD, Far-Infrared (FIR) (IRAS 60 and 100$\mu$m), and X-ray (ROSAT PSPC, 0.2-2.4keV) images are combined to investigate local and global emission properties. NGC~247 is unique since it has the lowest L$_{FIR}$, and FIR/B ratio of the large (D$_{25B}>$8$^{\prime}$) Sc's observed by IRAS. It may be considered the best example of a FIR quiescent galaxy, although its 60/100$\mu$m colour (dust temperature) is not abnormal for an Sc. There are 4-5 X-ray sources (L$_{X} \sim$ 5E37--3E38 erg s$^{-1}$) located in the disk of the galaxy. These sources are not coincident with the regions of 60$\mu$m emission, consistent with the interpretation that the X-ray sources are old population binary systems. Constraints are put on X-ray diffuse emission and source variability.

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